Expansion of a PBPK model to predict disposition in pregnant women of drugs cleared via multiple CYP enzymes, including CYP2B6, CYP2C9 and CYP2C19

PubMed Central

Ke, Alice Ban; Nallani, Srikanth C; Zhao, Ping; Rostami-Hodjegan, Amin; Unadkat, Jashvant D

2014-01-01

Aim Conducting PK studies in pregnant women is challenging. Therefore, we asked if a physiologically-based pharmacokinetic (PBPK) model could be used to predict the disposition in pregnant women of drugs cleared by multiple CYP enzymes. Methods We expanded and verified our previously published pregnancy PBPK model by incorporating hepatic CYP2B6 induction (based on in vitro data), CYP2C9 induction (based on phenytoin PK) and CYP2C19 suppression (based on proguanil PK), into the model. This model accounted for gestational age-dependent changes in maternal physiology and hepatic CYP3A, CYP1A2 and CYP2D6 activity. For verification, the pregnancy-related changes in the disposition of methadone (cleared by CYP2B6, 3A and 2C19) and glyburide (cleared by CYP3A, 2C9 and 2C19) were predicted. Results Predicted mean post-partum to second trimester (PP : T2) ratios of methadone AUC, Cmax and Cmin were 1.9, 1.7 and 2.0, vs. observed values 2.0, 2.0 and 2.6, respectively. Predicted mean post-partum to third trimester (PP : T3) ratios of methadone AUC, Cmax and Cmin were 2.1, 2.0 and 2.4, vs. observed values 1.7, 1.7 and 1.8, respectively. Predicted PP : T3 ratios of glyburide AUC, Cmax and Cmin were 2.6, 2.2 and 7.0 vs. observed values 2.1, 2.2 and 3.2, respectively. Conclusions Our PBPK model integrating prior physiological knowledge, in vitro and in vivo data, allowed successful prediction of methadone and glyburide disposition during pregnancy. We propose this expanded PBPK model can be used to evaluate different dosing scenarios, during pregnancy, of drugs cleared by single or multiple CYP enzymes. PMID:23834474

Expansion of a PBPK model to predict disposition in pregnant women of drugs cleared via multiple CYP enzymes, including CYP2B6, CYP2C9 and CYP2C19.

PubMed

Ke, Alice Ban; Nallani, Srikanth C; Zhao, Ping; Rostami-Hodjegan, Amin; Unadkat, Jashvant D

2014-03-01

Conducting PK studies in pregnant women is challenging. Therefore, we asked if a physiologically-based pharmacokinetic (PBPK) model could be used to predict the disposition in pregnant women of drugs cleared by multiple CYP enzymes. We expanded and verified our previously published pregnancy PBPK model by incorporating hepatic CYP2B6 induction (based on in vitro data), CYP2C9 induction (based on phenytoin PK) and CYP2C19 suppression (based on proguanil PK), into the model. This model accounted for gestational age-dependent changes in maternal physiology and hepatic CYP3A, CYP1A2 and CYP2D6 activity. For verification, the pregnancy-related changes in the disposition of methadone (cleared by CYP2B6, 3A and 2C19) and glyburide (cleared by CYP3A, 2C9 and 2C19) were predicted. Predicted mean post-partum to second trimester (PP : T2 ) ratios of methadone AUC, Cmax and Cmin were 1.9, 1.7 and 2.0, vs. observed values 2.0, 2.0 and 2.6, respectively. Predicted mean post-partum to third trimester (PP : T3 ) ratios of methadone AUC, Cmax and Cmin were 2.1, 2.0 and 2.4, vs. observed values 1.7, 1.7 and 1.8, respectively. Predicted PP : T3 ratios of glyburide AUC, Cmax and Cmin were 2.6, 2.2 and 7.0 vs. observed values 2.1, 2.2 and 3.2, respectively. Our PBPK model integrating prior physiological knowledge, in vitro and in vivo data, allowed successful prediction of methadone and glyburide disposition during pregnancy. We propose this expanded PBPK model can be used to evaluate different dosing scenarios, during pregnancy, of drugs cleared by single or multiple CYP enzymes. © 2013 The British Pharmacological Society.

Contributions of Human Cytochrome P450 Enzymes to Glyburide Metabolism*

PubMed Central

Zhou, Lin; Naraharisetti, Suresh B.; Liu, Li; Wang, Honggang; Lin, Yvonne S.; Isoherranen, Nina; Unadkat, Jashvant D.; Hebert, Mary F.; Mao, Qingcheng

2011-01-01

Glyburide (GLB) is a widely used oral sulfonylurea for the treatment of gestational diabetes. Therapeutic use of GLB is often complicated by a substantial inter-individual variability in the pharmacokinetics and pharmacodynamics of the drug in human populations, which might be caused by inter-individual variations in factors such as GLB metabolism. Therefore, there has been a continued interest in identifying human cytochrome P450 (CYP) isoforms that play a major role in the metabolism of GLB. However, contrasting data are available in the present literature in this regard. In the present study, we systematically investigated the contributions of various human CYP isoforms (CYP3A4, CYP3A5, CYP2C8, CYP2C9, and CYP2C19) to in vitro metabolism of GLB. GLB depletion and metabolite formation in human liver microsomes were most significantly inhibited by the CYP3A inhibitor ketoconazole compared with the inhibitors of other CYP isoforms. Furthermore, multiple correlation analysis between GLB depletion and individual CYP activities was performed, demonstrating a significant correlation between GLB depletion and the CYP3A probe activity in 16 individual human liver microsomal preparations, but not between GLB depletion and the CYP2C19, CYP2C8, or CYP2C9 probe activity. By using recombinant supersomes overexpressing individual human CYP isoforms, we found that GLB could be depleted by all the enzymes tested; however, the intrinsic clearance (Vmax/Km) of CYP3A4 for GLB depletion was 4 – 17 times greater than that of other CYP isoforms. These results confirm that human CYP3A4 is the major enzyme invovled in the in vitro metabolism of GLB. PMID:20437462

The effect of polymorphic metabolism enzymes on serum phenytoin level.

PubMed

Ozkaynakci, Aydan; Gulcebi, Medine Idrizoglu; Ergeç, Deniz; Ulucan, Korkut; Uzan, Mustafa; Ozkara, Cigdem; Guney, Ilter; Onat, Filiz Yilmaz

2015-03-01

Phenytoin has a widespread use in epilepsy treatment and is mainly metabolized by hepatic cytochrome P450 enzymes (CYP). We have investigated CYP2C9*2, CYP2C9*3, CYP2C19*2 and CYP2C19*3 allelic variants in a Turkish population of patients on phenytoin therapy. Patients on phenytoin therapy (n = 102) for the prevention of epileptic seizures were included. Polymorphic alleles were analyzed by restriction fragment length polymorphism method. Serum concentrations of phenytoin were measured by fluorescence polarization immune assay method. The most frequent genotype was detected for CYP2C9 wild-type alleles (78.43 %), whereas CYP2C19*2/*2 (5.88 %) was the least frequent genotype group. According to the classification made with both enzyme polymorphisms, CYP2C9*1/*1-CYP2C19*1/*1 (G1: 41.17 %) genotype group was the most frequent whereas CYP2C9*1/*2-CYP2C19*1/*3 (G7: 0.98 %) was the least frequent one. The highest mean phenytoin level (27.95 ± 1.85 µg/ml) was detected in the G8 genotype group (CYP2C9*1/*3-CYP2C19*2/*3) and the G1 genotype group showed the lowest mean phenytoin level (7.43 ± 0.73 µg/ml). The mean serum concentration of phenytoin of the polymorphic patients with epilepsy was higher than that for the wild-type alleles both in the monotherapy and polytherapy patients. These results show the importance of the genetic polymorphism analysis of the main metabolizing enzyme groups of phenytoin for the dose adjustment.

Traditional Herbal Formulas to as Treatments for Musculoskeletal Disorders: Their Inhibitory Effects on the Activities of Human Microsomal Cytochrome P450s and UDP-glucuronosyltransferases

PubMed Central

Jin, Seong Eun; Seo, Chang-Seob; Shin, Hyeun-Kyoo; Ha, Hyekyung

2016-01-01

Objective: The aim of this study was to assess the influence of traditional herbal formulas, including Bangpungtongseong-san (BPTSS; Fangfengtongsheng-san, Bofu-tsusho-san), Ojeok-san (OJS; Wuji-san, Goshaku-san), and Oyaksungi-san (OYSGS; Wuyaoshungi-san, Uyakujyunki-san), on the activities of the human cytochrome P450s (CYP450s) and UDP-glucuronosyltransferases (UGTs), which are drug-metabolizing enzymes. Materials and Methods: The activities of the major human CYP450 isozymes (CYP1A2, CYP3A4, CYP2B6, CYP2C9, CYP2C19, CYP2D6, and CYP2E1) and UGTs (UGT1A1, UGT1A4, and UGT2B7) were investigated using in vitro fluorescence-based and luminescence-based enzyme assays, respectively. The inhibitory effects of the herbal formulas were characterized, and their IC50 values were determined. Results: BPTSS inhibited the activities of CYP1A2, CYP2C19, CYP2E1, and UGT1A1 while it exerted relatively weak inhibition on CYP2B6, CYP2C9, CYP2D6, and CYP3A4. BPTSS also negligibly inhibited the activities of UGT1A4 and UGT2B7, with IC50 values in the excess of 1000 μg/mL. OJS and OYSGS inhibited the activity of CYP2D6, whereas they exhibited no inhibition of the UGT1A4 activity at doses <1000 μg/mL. In addition, OJS inhibited the CYP1A2 activity but exerted a relatively weak inhibition on the activities of CYP2C9, CYP2C19, CYP2E1, and CYP3A4. Conversely, OJS negligibly inhibited the activities of CYP2B6, UGT1A1, and UGT2B7 with IC50 values in excess of 1000 μg/mL. OYSGS weakly inhibited the activities of CYP1A2, CYP2C19, CYP2E1, CYP3A4, and UGT1A1, with a negligible inhibition on the activities of CYP2B6, CYP2C9, and UGT2B7, with IC50 values in excess of 1000 μg/mL. Conclusions: These results provide information regarding the safety and effectiveness of BPTSS, OJS, and OYSGS when combined with conventional drugs. SUMMARY Bangpungtongseong-san inhibited the activities of human microsomal CYP1A2, CYP2C19, CYP2E1, and UGT1A1, with a negligibly inhibition on the activities of CYP2B6, CYP2C9, CYP2D6, CYP3A4, UGT1A4, and UGT2B7Ojeok-san (OJS) inhibited the CYP1A2 and CYP2D6 mediated metabolism while showing a comparatively weak inhibition against CYP2B6, CYP2C9, CYP2C19, CYP2E1, CYP3A4, and UGT1A1 in human microsomesOyaksungi-san (OYSGS) inhibited the activities of human microsomal CYP2D6, with a relatively weak inhibition on the activities of CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2E1, CYP3A4, UGT1A1, and UGT2B7OJS showed no inhibition on the activities of human microsomal UGT1A4 and UGT2B7, and OYSGS did not affect the human microsomal UGT1A4 activity. Abbreviations used: BPTSS: Bangpungtongseong-san, OJS: Ojeok-san, OYSGS: Oyaksungi-san, CYP450s: cytochrome P450s, UGTs: UDP-glucuronosyltransferases, MSDs: Musculoskeletal disorders, NSAIDs: nonsteroidal anti-inflammatory drugs, EOMCC: 7-ethoxy-methyloxy-3-cyanocoumarin, DBOMF: di(benzyloxymethoxy)fluorescein, BOMCC: 7-benzyloxy-4-trifluoromethylcoumarin, HPLC: High-performance liquid chromatography, PDA: photo diode array, SEM: standard error of the mean, UDPGA: uridine 5’-diphosphoglucuronic acid. PMID:27867264

Prediction of Cytochrome P450 Profiles of Environmental Chemicals with QSAR Models Built from Drug-like Molecules

EPA Science Inventory

The human cytochrome P450 (CYP450) enzyme family is involved in the biotransformation of many environmental chemicals. As part of the U.S. Tox21 effort, we profiled the CYP450 activity of ~2800 chemicals predominantly of environmental concern against CYP1A2, CYP2C19, CYP2C9, CYP2...

The formation of estrogen-like tamoxifen metabolites and their influence on enzyme activity and gene expression of ADME genes.

PubMed

Johänning, Janina; Kröner, Patrick; Thomas, Maria; Zanger, Ulrich M; Nörenberg, Astrid; Eichelbaum, Michel; Schwab, Matthias; Brauch, Hiltrud; Schroth, Werner; Mürdter, Thomas E

2018-03-01

Tamoxifen, a standard therapy for breast cancer, is metabolized to compounds with anti-estrogenic as well as estrogen-like action at the estrogen receptor. Little is known about the formation of estrogen-like metabolites and their biological impact. Thus, we characterized the estrogen-like metabolites tamoxifen bisphenol and metabolite E for their metabolic pathway and their influence on cytochrome P450 activity and ADME gene expression. The formation of tamoxifen bisphenol and metabolite E was studied in human liver microsomes and Supersomes™. Cellular metabolism and impact on CYP enzymes was analyzed in upcyte® hepatocytes. The influence of 5 µM of tamoxifen, anti-estrogenic and estrogen-like metabolites on CYP activity was measured by HPLC MS/MS and on ADME gene expression using RT-PCR analyses. Metabolite E was formed from tamoxifen by CYP2C19, 3A and 1A2 and from desmethyltamoxifen by CYP2D6, 1A2 and 3A. Tamoxifen bisphenol was mainly formed from (E)- and (Z)-metabolite E by CYP2B6 and CYP2C19, respectively. Regarding phase II metabolism, UGT2B7, 1A8 and 1A3 showed highest activity in glucuronidation of tamoxifen bisphenol and metabolite E. Anti-estrogenic metabolites (Z)-4-hydroxytamoxifen, (Z)-endoxifen and (Z)-norendoxifen inhibited the activity of CYP2C enzymes while tamoxifen bisphenol consistently induced CYPs similar to rifampicin and phenobarbital. On the transcript level, highest induction up to 5.6-fold was observed for CYP3A4 by tamoxifen, (Z)-4-hydroxytamoxifen, tamoxifen bisphenol and (E)-metabolite E. Estrogen-like tamoxifen metabolites are formed in CYP-dependent reactions and are further metabolized by glucuronidation. The induction of CYP activity by tamoxifen bisphenol and the inhibition of CYP2C enzymes by anti-estrogenic metabolites may lead to drug-drug-interactions.

To Genotype or Phenotype for Personalized Medicine? CYP450 Drug Metabolizing Enzyme Genotype-Phenotype Concordance and Discordance in the Ecuadorian Population.

PubMed

De Andrés, Fernando; Terán, Santiago; Hernández, Francisco; Terán, Enrique; LLerena, Adrián

2016-12-01

Genetic variations within the cytochrome P450 (CYP450) superfamily of drug metabolizing enzymes confer substantial person-to-person and between-population differences in pharmacokinetics, and by extension, highly variable clinical effects of medicines. In this context, "personalized medicine," "precision medicine," and "stratified medicine" are related concepts attributed to what is essentially targeted therapeutics and companion diagnostics, aimed at improving safety and effectiveness of health interventions. We report here, to the best of our knowledge, the first comparative clinical pharmacogenomics study, in an Ecuadorian population sample, of five key CYP450s involved in drug metabolism: CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4. In 139 unrelated, medication-free, and healthy Ecuadorian subjects, we measured the phenotypic activity of these drug metabolism pathways using the CEIBA multiplexed phenotyping cocktail. The subjects were genotyped for each CYP450 enzyme gene as well. Notably, based on the CYP450 metabolic phenotypes estimated by the genotype data, 0.75% and 3.10% of the subjects were genotypic poor metabolizers (gPMs) for CYP2C19 and CYP2D6, respectively. Additionally, on the other extreme, genotype-estimated ultrarapid metabolizer (gUMs) phenotype was represented by 15.79% of CYP2C19, and 5.43% of CYP2D6. There was, however, considerable discordance between directly measured phenotypes (mPMs and mUMs) and the above genotype-estimated enzyme phenotypes. For example, among individuals genotypically carrying enhanced activity alleles (gUMs), many showed a lower actual drug metabolism capacity than expected by their genotypes, even lower than individuals with reduced or no activity alleles. In conclusion, for personalized medicine in the Ecuadorian population, we recommend CYP450 multiplexed phenotyping, or genotyping and phenotyping in tandem, rather than CYP450 genotypic tests alone. Additionally, we recommend, in consideration of equity, ethical, and inclusive representation in global science, further precision medicine research and funding in support of neglected or understudied populations worldwide.

CYP2C19 activity and cardiovascular risk factors in patients with an acute coronary syndrome.

PubMed

Martínez-Quintana, Efrén; Rodríguez-González, Fayna; Medina-Gil, José María; Garay-Sánchez, Paloma; Tugores, Antonio

2017-09-20

CYP2C19 is a major isoform of cytochrome P450 that metabolizes a number of drugs and is involved in the glucocorticoids synthesis. CYP2C19 polymorphisms have been associated with the genetic risk for type 2 diabetes. Five hundred and three patients with an acute coronary event were studied to assess the association between the CYP2C19 activity (CYP2C19*2, CYP2C19*3 and CYP2C19*17 variants) and the type of acute coronary syndrome, cardiovascular risk factors (arterial systemic hypertension, diabetes mellitus, dyslipidemia and smoking), analytical parameters and the extent and severity of coronary atherosclerosis. Genotype distribution in our series was similar to that expected in the Caucasian population. Among the traditional cardiovascular risk factors, very poor metabolizer patients (*2/*2, *3/*3 or *2/*3) had a greater tendency to present diabetes mellitus needing insuline (P=.067). Conversely, when we compared very poor, poor and normal metabolizers vs. rapid and ultrarapid metabolizers we found significant differences in those diabetic patients under insulin treatment (64 patients [18%] vs. 17 patients [11%]; P=.032). On the contrary, analytical parameters, systemic arterial hypertension, dyslipidemia, smoking or the personal/family history of coronary artery disease did not reach statistical significance regardless of CYP2C19 activity. Similarly, the number and the type of coronary disease (thrombotic, fibrotic or both) did not differ between patients with different CYP2C19 enzyme activity. Patients with an acute coronary event and a very poor, poor and normal CYP2C19 metabolizer genotype have a higher prevalence of diabetes mellitus needing insuline than patients with the rapid and ultrarapid metabolizers CPY2C19 genotype. Copyright © 2017 Elsevier España, S.L.U. All rights reserved.

Engineering human cytochrome P450 enzymes into catalytically self-sufficient chimeras using molecular Lego.

PubMed

Dodhia, Vikash Rajnikant; Fantuzzi, Andrea; Gilardi, Gianfranco

2006-10-01

The membrane-bound human cytochrome P450s have essential roles in the metabolism of endogenous compounds and drugs. Presented here are the results on the construction and characterization of three fusion proteins containing the N-terminally modified human cytochrome P450s CYP2C9, CY2C19 and CYP3A4 fused to the soluble NADPH-dependent oxidoreductase domain of CYP102A1 from Bacillus megaterium. The constructs, CYP2C9/BMR, CYP2C19/BMR and CYP3A4/BMR are well expressed in Escherichia coli as holo proteins. The chimeras can be purified in the absence of detergent and the purified enzymes are both active and correctly folded in the absence of detergent, as demonstrated by circular dichroism and functional studies. Additionally, in comparison with the parent P450 enzyme, these chimeras have greatly improved solubility properties. The chimeras are catalytically self-sufficient and present turnover rates similar to those reported for the native enzymes in reconstituted systems, unlike previously reported mammalian cytochrome P450 fusion proteins. Furthermore the specific activities of these chimeras are not dependent on the enzyme concentration present in the reaction buffer and they do not require the addition of accessory proteins, detergents or phospholipids to be fully active. The solubility, catalytic self-sufficiency and wild-type like activities of these chimeras would greatly simplify the studies of cytochrome P450 mediated drug metabolism in solution.

The paraoxonase-1 pathway is not a major bioactivation pathway of clopidogrel in vitro

PubMed Central

Ancrenaz, V; Desmeules, J; James, R; Fontana, P; Reny, J-L; Dayer, P; Daali, Y

2012-01-01

BACKGROUND AND PURPOSE Clopidogrel is a prodrug bioactivated by cytochrome P450s (CYPs). More recently, paraoxonase-1 (PON1) has been proposed as a major contributor to clopidogrel metabolism. The purpose of this study was to assess the relative contribution of CYPs and PON1 to clopidogrel metabolism in vitro. EXPERIMENTAL APPROACH Clopidogrel metabolism was studied in human serum, recombinant PON1 enzyme (rePON1), pooled human liver microsomes (HLMs), HLMs with the CYP2C19*1/*1 genotype and HLMs with the CYP2C19*2/*2 genotype. Inhibition studies were also performed using specific CYP inhibitors and antibodies. Clopidogrel and its metabolites were measured using LC/MS/MS method. KEY RESULTS PON1 activity was highest in the human serum and there was no difference in PON1 activity between any of the HLM groups. The production of clopidogrel's active metabolite (clopidogrel-AM) from 2-oxo-clopidogrel in pooled HLMs was approximately 500 times that in serum. When 2-oxo-clopidogrel was incubated with rePON1, clopidogrel-AM was not detected. Clopidogrel-AM production from 2-oxo-clopidogrel was lower in CYP2C19*2/*2 HLMs compared with CYP2C19*1/*1 HLMs, while PON1 activity in HLMs with both genotypes was similar. Moreover, incubation with inhibitors of CYP3A, CYP2B6 and CYP2C19 significantly reduced clopidogrel bioactivation while a PON1 inhibitor, EDTA, had only a weak inhibitory effect. CONCLUSION AND IMPLICATIONS This in vitro study shows that the contribution of PON1 to clopidogrel metabolism is limited at clinically relevant concentrations. Moreover, CYP2C19, CYP2B6 and CYP3A play important roles in the bioactivation of clopidogrel. PMID:22428615

Metabolism of deltamethrin and cis- and trans-permethrin by human expressed cytochrome P450 and carboxylesterase enzymes.

PubMed

Hedges, Laura; Brown, Susan; MacLeod, A Kenneth; Vardy, Audrey; Doyle, Edward; Song, Gina; Moreau, Marjory; Yoon, Miyoung; Osimitz, Thomas G; Lake, Brian G

2018-06-04

The metabolism of the pyrethroids deltamethrin (DLM), cis-permethrin (CPM) and trans-permethrin (TPM) was studied in human expressed cytochrome P450 (CYP) and carboxylesterase (CES) enzymes. DLM, CPM and TPM were metabolised by human CYP2B6 and CYP2C19, with the highest apparent intrinsic clearance (CL int ) values for pyrethroid metabolism being observed with CYP2C19. Other CYP enzymes contributing to the metabolism of one or more of the three pyrethroids were CYP1A2, CYP2C8, CYP2C9*1, CYP2D6*1, CYP3A4 and CYP3A5. None of the pyrethroids were metabolised by CYP2A6, CYP2E1, CYP3A7 or CYP4A11. DLM, CPM and TPM were metabolised by both human CES1 and CES2 enzymes. Apparent CL int values for pyrethroid metabolism by CYP and CES enzymes were scaled to per gram of adult human liver using abundance values for microsomal CYP enzymes and for CES enzymes in liver microsomes and cytosol. TPM had the highest and CPM the lowest apparent CL int values for total metabolism (CYP and CES enzymes) per gram of adult human liver. Due to their higher abundance, all three pyrethroids were extensively metabolised by CES enzymes in adult human liver, with CYP enzymes only accounting for 2%, 10% and 1% of total metabolism for DLM, CPM and TPM, respectively.

Identification of human cytochrome P450 and flavin-containing monooxygenase enzymes involved in the metabolism of lorcaserin, a novel selective human 5-hydroxytryptamine 2C agonist.

PubMed

Usmani, Khawja A; Chen, Weichao G; Sadeque, Abu J M

2012-04-01

Lorcaserin, a selective serotonin 5-hydroxytryptamine 2C receptor agonist, is being developed for weight management. The oxidative metabolism of lorcaserin, mediated by recombinant human cytochrome P450 (P450) and flavin-containing monooxygenase (FMO) enzymes, was examined in vitro to identify the enzymes involved in the generation of its primary oxidative metabolites, N-hydroxylorcaserin, 7-hydroxylorcaserin, 5-hydroxylorcaserin, and 1-hydroxylorcaserin. Human CYP1A2, CYP2A6, CYP2B6, CYP2C19, CYP2D6, CYP3A4, and FMO1 are major enzymes involved in N-hydroxylorcaserin; CYP2D6 and CYP3A4 are enzymes involved in 7-hydroxylorcaserin; CYP1A1, CYP1A2, CYP2D6, and CYP3A4 are enzymes involved in 5-hydroxylorcaserin; and CYP3A4 is an enzyme involved in 1-hydroxylorcaserin formation. In 16 individual human liver microsomal preparations (HLM), formation of N-hydroxylorcaserin was correlated with CYP2B6, 7-hydroxylorcaserin was correlated with CYP2D6, 5-hydroxylorcaserin was correlated with CYP1A2 and CYP3A4, and 1-hydroxylorcaserin was correlated with CYP3A4 activity at 10.0 μM lorcaserin. No correlation was observed for N-hydroxylorcaserin with any P450 marker substrate activity at 1.0 μM lorcaserin. N-Hydroxylorcaserin formation was not inhibited by CYP1A2, CYP2A6, CYP2B6, CYP2C19, CYP2D6, and CYP3A4 inhibitors at the highest concentration tested. Furafylline, quinidine, and ketoconazole, selective inhibitors of CYP1A2, CYP2D6, and CYP3A4, respectively, inhibited 5-hydroxylorcaserin (IC(50) = 1.914 μM), 7-hydroxylorcaserin (IC(50) = 0.213 μM), and 1-hydroxylorcaserin formation (IC(50) = 0.281 μM), respectively. N-Hydroxylorcaserin showed low and high K(m) components in HLM and 7-hydroxylorcaserin showed lower K(m) than 5-hydroxylorcaserin and 1-hydroxylorcaserin in HLM. The highest intrinsic clearance was observed for N-hydroxylorcaserin, followed by 7-hydroxylorcaserin, 5-hydroxylorcaserin, and 1-hydroxylorcaserin in HLM. Multiple human P450 and FMO enzymes catalyze the formation of four primary oxidative metabolites of lorcaserin, suggesting that lorcaserin has a low probability of drug-drug interactions by concomitant medications.

Update on the Genetic Polymorphisms of Drug-Metabolizing Enzymes in Antiepileptic Drug Therapy

PubMed Central

Saruwatari, Junji; Ishitsu, Takateru; Nakagawa, Kazuko

2010-01-01

Genetic polymorphisms in the genes that encode drug-metabolizing enzymes are implicated in the inter-individual variability in the pharmacokinetics and pharmaco-dynamics of antiepileptic drugs (AEDs). However, the clinical impact of these polymorphisms on AED therapy still remains controversial. The defective alleles of cytochrome P450 (CYP) 2C9 and/or CYP2C19 could affect not only the pharmacokinetics, but also the pharmacodynamics of phenytoin therapy. CYP2C19 deficient genotypes were associated with the higher serum concentration of an active metabolite of clobazam, N-desmethylclobazam, and with the higher clinical efficacy of clobazam therapy than the other CYP2C19 genotypes. The defective alleles of CYP2C9 and/or CYP2C19 were also found to have clinically significant effects on the inter-individual variabilities in the population pharmacokinetics of phenobarbital, valproic acid and zonisamide. EPHX1 polymorphisms may be associated with the pharmacokinetics of carbamazepine and the risk of phenytoin-induced congenital malformations. Similarly, the UDP-glucuronosyltransferase 2B7 genotype may affect the pharmacokinetics of lamotrigine. Gluthatione S-transferase null genotypes are implicated in an increased risk of hepatotoxicity caused by carbamazepine and valproic acid. This article summarizes the state of research on the effects of mutations of drug-metabolizing enzymes on the pharmacokinetics and pharmacodynamics of AED therapies. Future directions for the dose-adjustment of AED are discussed. PMID:27713373

Delamanid does not inhibit or induce cytochrome p450 enzymes in vitro.

PubMed

Shimokawa, Yoshihiko; Sasahara, Katsunori; Yoda, Noriaki; Mizuno, Katsuhiko; Umehara, Ken

2014-01-01

Delamanid is a new drug for the treatment of multidrug-resistant tuberculosis. Individuals who are co-infected with human immunodeficiency virus and Mycobacterium tuberculosis may require treatment with a number of medications that might interact significantly with the CYP enzyme system as inhibitors or inducers. It is therefore important to understand how drugs in development for the treatment of tuberculosis will affect CYP enzyme metabolism. The ability of delamanid to inhibit or induce CYP enzymes was investigated in vitro using human liver microsomes or human hepatocytes. Delamanid (100 µM) had little potential for mechanism-based inactivation on eight CYP isoforms (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4). Delamanid's metabolites were noted to inhibit the metabolism of some CYP isoforms, but these effects were observed only at metabolite concentrations that were well above those observed in human plasma during clinical trials. Delamanid (≤10 µM) did not induce CYP1A2, CYP2C9, and CYP3A4 activities in human hepatocytes, and there were no increases in CYP1A2, CYP2B6, CYP2C9, and CYP3A4 mRNA levels. Taken together, these data suggest that delamanid is unlikely to cause clinically relevant drug-drug interactions when co-administered with products that are metabolized by the CYP enzyme system.

Identification of the major human hepatic and placental enzymes responsible for the biotransformation of glyburide

PubMed Central

Zharikova, Olga L.; Fokina, Valentina M.; Nanovskaya, Tatiana N.; Hill, Ronald A.; Mattison, Donald R.; Hankins, Gary D.V.; Ahmed, Mahmoud S.

2014-01-01

One of the factors affecting the pharmacokinetics (PK) of a drug during pregnancy is the activity of hepatic and placental metabolizing enzymes. Recently, we reported on the biotransformation of glyburide by human hepatic and placental microsomes to six metabolites that are structurally identical between the two tissues. Two of the metabolites, 4-trans- (M1) and 3-cis-hydroxycyclohexyl glyburide (M2b), were previously identified in plasma and urine of patients treated with glyburide and are pharmacologically active. The aim of this investigation was to identify the major human hepatic and placental CYP450 isozymes responsible for the formation of each metabolite of glyburide. This was achieved by the use of chemical inhibitors selective for individual CYP isozymes and antibodies raised against them. The identification was confirmed by the kinetic constants for the biotransformation of glyburide by cDNA-expressed enzymes. The data revealed that the major hepatic isozymes responsible for the formation of each metabolite are as follows: CYP3A4 (ethylene-hydroxylated glyburide (M5), 3-trans-(M3) and 2-trans-(M4) cyclohexyl glyburide); CYP2C9 (M1, M2a( 4-cis-) and M2b); CYP2C8 (M1 and M2b); and CYP2C19 (M2a). Human placental microsomal CYP19/aromatase was the major isozyme responsible for the biotransformation of glyburide to predominantly M5. The formation of significant amounts of M5 by CYP19 in the placenta could render this metabolite more accessible to the fetal circulation. The multiplicity of enzymes biotransforming glyburide and the metabolites formed underscores the potential for its drug interactions in vivo. PMID:19679108

Identification of the major human hepatic and placental enzymes responsible for the biotransformation of glyburide.

PubMed

Zharikova, Olga L; Fokina, Valentina M; Nanovskaya, Tatiana N; Hill, Ronald A; Mattison, Donald R; Hankins, Gary D V; Ahmed, Mahmoud S

2009-12-15

One of the factors affecting the pharmacokinetics (PK) of a drug during pregnancy is the activity of hepatic and placental metabolizing enzymes. Recently, we reported on the biotransformation of glyburide by human hepatic and placental microsomes to six metabolites that are structurally identical between the two tissues. Two of the metabolites, 4-trans-(M1) and 3-cis-hydroxycyclohexyl glyburide (M2b), were previously identified in plasma and urine of patients treated with glyburide and are pharmacologically active. The aim of this investigation was to identify the major human hepatic and placental CYP450 isozymes responsible for the formation of each metabolite of glyburide. This was achieved by the use of chemical inhibitors selective for individual CYP isozymes and antibodies raised against them. The identification was confirmed by the kinetic constants for the biotransformation of glyburide by cDNA-expressed enzymes. The data revealed that the major hepatic isozymes responsible for the formation of each metabolite are as follows: CYP3A4 (ethylene-hydroxylated glyburide (M5), 3-trans-(M3) and 2-trans-(M4) cyclohexyl glyburide); CYP2C9 (M1, M2a (4-cis-) and M2b); CYP2C8 (M1 and M2b); and CYP2C19 (M2a). Human placental microsomal CYP19/aromatase was the major isozyme responsible for the biotransformation of glyburide to predominantly M5. The formation of significant amounts of M5 by CYP19 in the placenta could render this metabolite more accessible to the fetal circulation. The multiplicity of enzymes biotransforming glyburide and the metabolites formed underscores the potential for its drug interactions in vivo.

Routine Screening for CYP2C19 Polymorphisms for Patients being Treated with Clopidogrel is not Recommended

PubMed Central

Hong, Robert A; Khan, Zia R; Valentin, Mona R; Badawi, Ramy A

2015-01-01

Recent efforts directed at potential litigation in Hawai‘i have resulted in a renewed interest for genetic screening for cytochrome P450 2C19 (CYP2C19) polymorphisms in patients treated with clopidogrel. Clopidogrel is an antiplatelet agent, frequently used in combination with aspirin, for the prevention of thrombotic complications with acute coronary syndrome and in patients undergoing percutaneous coronary interventions. Cytochrome P-450 (CYP) 2C19 is an enzyme involved in the bioactivation of clopidogrel from a pro-drug to an active inhibitor of platelet action. Patients of Asian and Pacific Island background have been reported to have an increase in CYP2C19 polymorphisms associated with loss-of-function of this enzyme when compared to other ethnicities. This has created an interest in genetic testing for CYP2C19 polymorphisms in Hawai‘i. Based upon our review of the current literature, we do not feel that there is support for the routine screening for CYP2C19 polymorphisms in patients being treated with clopidogrel; furthermore, the results of genetic testing may not be helpful in guiding therapeutic decisions. We recommend that decisions on the type of antiplatelet treatment be made based upon clinical evidence of potential differential outcomes associated with the use of these agents rather than on the basis of genetic testing. PMID:25628978

Use of multi-dose activated charcoal in phenytoin toxicity secondary to genetic polymorphism.

PubMed

Chan, Betty S H; Sellors, Kate; Chiew, Angela L; Buckley, Nicholas A

2015-02-01

Phenytoin is metabolised in the liver by cytochrome (CYP)2C9 and 2C19 enzymes. Due to saturation of enzyme capacity, the elimination half-life is prolonged at supratherapeutic levels. Genetic polymorphisms of CYP2C9 and 2C19 are reasonably common and further prolong the elimination of phenytoin. There are conflicting reports regarding whether multiple-dose activated charcoal (MDAC) significantly increases the clearance of phenytoin in poisoning. We present 3 patients with phenytoin toxicity and very slow elimination secondary to reduced CYP enzyme function from genetic polymorphisms. MDAC was used in two patients and led to rapid and large reductions in the measured elimination half-lives. This is contrasted with very prolonged elimination in a third patient who did not receive MDAC. MDAC may play a role in the management of chronic phenytoin toxicity, especially in those with very slow endogenous elimination secondary to genetic polymorphisms.

In vitro metabolism of nobiletin, a polymethoxy-flavonoid, by human liver microsomes and cytochrome P450.

PubMed

Koga, Nobuyuki; Ohta, Chiho; Kato, Yoshihisa; Haraguchi, Koichi; Endo, Tetsuya; Ogawa, Kazunori; Ohta, Hideaki; Yano, Masamichi

2011-11-01

Cytochrome P450 enzymes (CYPs) in the liver metabolize drugs prior to excretion, with different enzymes acting at different molecular motifs. At present, the human CYPs responsible for the metabolism of the flavonoid, nobiletin (NBL), are unidentified. We investigated which enzymes were involved using human liver microsomes and 12 cDNA-expressed human CYPs. Human liver microsomes metabolized NBL to three mono-demethylated metabolites (4'-OH-, 7-OH- and 6-OH-NBL) with a relative ratio of 1:4.1:0.5, respectively, by aerobic incubation with nicotinamide adenine dinucleotide phosphate (NADPH). Of 12 human CYPs, CYP1A1, CYP1A2 and CYP1B1 showed high activity for the formation of 4'-OH-NBL. CYP3A4 catalyzed the formation of 7-OH-NBL with the highest activity and of 6-OH-NBL with lower activity. CYP3A5 also catalyzed the formation of both metabolites but considerably more slowly than CYP3A4. In contrast, seven CYPs (CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP2E1) were inactive for NBL. Both ketoconazole and troleandomycin (CYP3A inhibitors) almost completely inhibited the formation of 7-OH- and 6-OH-NBL. Similarly, α-naphthoflavone (CYP1A1 inhibitor) and furafylline (CYP1A2 inhibitor) significantly decreased the formation of 4'-OH-NBL. These results suggest that CYP1A2 and CYP3A4 are the key enzymes in human liver mediating the oxidative demethylation of NBL in the B-ring and A-ring, respectively.

Metabolic characterization of (1-(5-fluoropentyl)-1H-indol-3-yl)(4-methyl-1-naphthalenyl)-methanone (MAM-2201) using human liver microsomes and cDNA-overexpressed cytochrome P450 enzymes.

PubMed

Kong, Tae Yeon; Kim, Ju-Hyun; Choi, Won Gu; Lee, Joo Young; Kim, Hee Seung; Kim, Jin Young; In, Moon Kyo; Lee, Hye Suk

2017-02-01

MAM-2201 is a synthetic cannabinoid that is increasingly found in recreational drug abusers and cases of severe intoxication. Thus, characterization of the metabolic pathways of MAM-2201 is necessary to predict individual pharmacokinetics and toxicity differences, and to avoid toxic drug-drug interactions. Collectively, 19 phase 1 metabolites of MAM-2201 were identified using liquid chromatography-Orbitrap mass spectrometry following human liver microsomal incubations in the presence of NADPH: 7 hydroxy-MAM-2201 (M1-M7), 4 dihydroxy-MAM-2201 (M8-M11), dihydrodiol-MAM-2201 (M12), N-(5-hydroxypentyl)-MAM-2201 (M13), hydroxy-M13 (M14), N-dealkyl-MAM-2201 (M15), 2 hydroxy-M15 (M16, M17), MAM-2201 N-pentanoic acid (M18), and hydroxy-M18 (M19). On the basis of intrinsic clearance values in human liver microsomes, hydroxy-MAM-2201 (M1), N-(5-hydroxypentyl)-MAM-2201 (M13), and hydroxy-M13 (M14) were the major metabolites. Based on an enzyme kinetics study using human cDNA-expressed cytochrome P450 (CYP) enzymes and an immunoinhibition study using selective CYP antibodies in human liver microsomes, CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 enzymes were responsible for MAM-2201 metabolism. The CYP3A4 enzyme played a prominent role in MAM-2201 metabolism, and CYP1A2, CYP2B6, CYP2C8, and CYP2C9 enzymes played major roles in the formation of some metabolites. MAM-2201 is extensively metabolized by multiple CYP enzymes, indicating that MAM-2201 and its metabolites should be used as markers of MAM-2201 abuse and toxicity. Graphical abstract In vitro metabolic pathways of MAM-2201 were characterized in human liver microsomes and recombinant CYPs using LC-HRMS analysis. Total 19 phase I metabolites were identified with predominant contribution of CYP3A4.

An in vitro approach to potential methadone metabolic-inhibition interactions.

PubMed

Bomsien, Stephanie; Skopp, Gisela

2007-09-01

The aim of this study was to assess the drug interaction potential of psychotropic medication on methadone N-demethylation using cDNA-expressed cytochrome P450 CYP enzymes. Methadone was incubated with various drugs (n = 10) and cDNA-expressed CYP3A4, CYP2D6, CYP2B6, CYP2C19 and CYP1A2 enzymes to screen for their inhibition potency. The nature of enzyme selective activity for inhibition was further investigated for potent inhibitors. To test for a mechanism-based component in inhibition, all substances were tested with preincubation and without. 2-Ethylidene-1,5-dimethyl-3,3-diphenylpyrrolidine (EDDP) concentration was determined by liquid chromatography/tandem mass spectrometry following liquid/liquid extraction. Formation of EDDP was catalysed by CYP3A4, CYP2D6 and CYP2C19. The N-demethylation of methadone was preferentially inhibited by amitriptyline, buprenorphine, methylenedioxymethamphetamine (MDMA) and zolpidem. Both amitriptyline and buprenorphine were strong, reversible inhibitors of CYP3A4. Similarly, amitriptyline and MDMA were identified as inhibitors of CYP2D6. Zolpidem revealed a mechanism-based inhibition of CYP3A4. Amitriptyline, MDMA and zolpidem are likely to slow down conversion of methadone and to increase its area under the curve (AUC). A consideration of the in vitro evidence of drug-methadone interactions should help to improve patient care during methadone maintenance treatment.

Evaluating the impact of type 2 diabetes mellitus on CYP450 metabolic activities: protocol for a case-control pharmacokinetic study.

PubMed

Gravel, Sophie; Chiasson, Jean-Louis; Dallaire, Suzanne; Turgeon, Jacques; Michaud, Veronique

2018-02-08

Diabetes affects more than 9% of the adult population worldwide. Patients with type 2 diabetes mellitus (T2DM) show variable responses to some drugs which may be due, in part, to variability in the functional activity of drug-metabolising enzymes including cytochromes P450 (CYP450s). CYP450 is a superfamily of enzymes responsible for xenobiotic metabolism. Knowledge must be gained on the impact of T2DM and related inflammatory processes on drug metabolism and its consequences on drug response. The aim of this study is to characterise the activity of CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4/5 in T2DM versus non-T2DM subjects following the administration of a cocktail of probe drug substrates. This single-centre clinical study proposes the first detailed characterisation of T2DM impacts on major CYP450 drug-metabolising enzyme activities. We intend to recruit 42 patients with controlled T2DM (A1C≤7%), 42 patients with uncontrolled T2DM (A1C>7%) and 42 non-diabetic control subjects. The primary objective is to determine and compare major CYP450 activities in patients with T2DM versus non-diabetic subjects by dosing in plasma and urine probe drug substrates and metabolites following the oral administration of a drug cocktail: caffeine (CYP1A2), bupropion (CYP2B6), tolbutamide (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), chlorzoxazone (CYP2E1) and midazolam (CYP3A4/5). Secondary objectives will evaluate the influence of variables such as glycaemia, insulinaemia, genetic polymorphisms and inflammation. The value of an endogenous biomarker of CYP3A activity is also evaluated. The first patient was recruited in May 2015 and patients will be enrolled up to completion of study groups. Approval was obtained from the ethic review board of the CHUM research centre (Montreal, Canada). NCT02291666. © Article author(s) (or their employer(s) unless otherwise stated in the text of the article) 2018. All rights reserved. No commercial use is permitted unless otherwise expressly granted.

Characterization CYP1A2, CYP2C9, CYP2C19 and CYP2D6 polymorphisms using HRMA in Psychiatry patients with schizophrenia and bipolar disease for personalized medicine.

PubMed

Yenilmez, Ebru Dundar; Tamam, Lut; Karaytug, Onur; Tuli, Abdullah

2018-06-19

The interindividual genetic variations in drug metabolizing enzymes effects the impact and toxicity in plenty of drugs. The CYP1A2, CYP2C9, CYP2C19 and CYP2D6 gene polymorphisms characterized using high resolution melting analysis (HRMA) in follow-up patients in psychiatry clinic as a preliminary preparation for personalized medicine. Genotyping of CYP1A2*1F, CYP2C9 *2, *3, CYP2C19 *2, *3 and *17 and CYP2D6 *3, *4 was conducted in 101 patients using HRMA. Genotype and allele frequencies of the CYP variants were found to be in equilibrium with the Hardy-Weinberg equation. The frequency of the CYP1A2*1F allele in schizophrenia and bipolar disease was 0.694 and 0.255, respectively. The CYP2C9 allele frequencies were 0.087 (CYP2C9*2), and 0.549 (CYP2C9*3) for bipolar; 0.278 (CYP2C9*2) and 0.648 (CYP2C9*3) in schizophrenias. The CYP2C19*2 and *17 allele frequencies was 0.111 and 0.185 in schizophrenia and variant *2 was 0.117 and variant *17 was 0.255 in bipolar group. The frequency of the CYP2D6*3 allele was 0.027 in schizophrenias. The frequencies for the CYP2D6*4 variant was 0.092 and 0.096 in schizophrenia and bipolar groups, respectively. The knowledge in pharmacogenomics and also the developments in molecular genetics are growing rapidly. In the future this can be expected to provide new methodologies in the prediction of the activity in drug metabolizing enzymes. The HRMA is a rapid and useful technique to identify the genotypes for drug dosage adjustment before therapy in psychiatry patients. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

The Ontogeny of Cytochrome P450 Enzyme Activity and Protein Abundance in Conventional Pigs in Support of Preclinical Pediatric Drug Research.

PubMed

Millecam, Joske; De Clerck, Laura; Govaert, Elisabeth; Devreese, Mathias; Gasthuys, Elke; Schelstraete, Wim; Deforce, Dieter; De Bock, Lies; Van Bocxlaer, Jan; Sys, Stanislas; Croubels, Siska

2018-01-01

Since the implementation of several legislations to improve pediatric drug research, more pediatric clinical trials are being performed. In order to optimize these pediatric trials, adequate preclinical data are necessary, which are usually obtained by juvenile animal models. The growing piglet has been increasingly suggested as a potential animal model due to a high degree of anatomical and physiological similarities with humans. However, physiological data in pigs on the ontogeny of major organs involved in absorption, distribution, metabolism, and excretion of drugs are largely lacking. The aim of this study was to unravel the ontogeny of porcine hepatic drug metabolizing cytochrome P450 enzyme (CYP450) activities as well as protein abundances. Liver microsomes from 16 conventional pigs (8 males and 8 females) per age group: 2 days, 4 weeks, 8 weeks, and 6-7 months were prepared. Activity measurements were performed with substrates of major human CYP450 enzymes: midazolam (CYP3A), tolbutamide (CYP2C), and chlorzoxazone (CYP2E). Next, the hepatic scaling factor, microsomal protein per gram liver (MPPGL), was determined to correct for enzyme losses during the fractionation process. Finally, protein abundance was determined using proteomics and correlated with enzyme activity. No significant sex differences within each age category were observed in enzyme activity or MPPGL. The biotransformation rate of all three substrates increased with age, comparable with human maturation of CYP450 enzymes. The MPPGL decreased from birth till 8 weeks of age followed by an increase till 6-7 months of age. Significant sex differences in protein abundance were observed for CYP1A2, CYP2A19, CYP3A22, CYP4V2, CYP2C36, CYP2E_1, and CYP2E_2. Midazolam and tolbutamide are considered good substrates to evaluate porcine CYP3A/2C enzymes, respectively. However, chlorzoxazone is not advised to evaluate porcine CYP2E enzyme activity. The increase in biotransformation rate with age can be attributed to an increase in absolute amount of CYP450 proteins. Finally, developmental changes were observed regarding the involvement of specific CYP450 enzymes in the biotransformation of the different substrates.

Similar substrate specificity of cynomolgus monkey cytochrome P450 2C19 to reported human P450 2C counterpart enzymes by evaluation of 89 drug clearances.

PubMed

Hosaka, Shinya; Murayama, Norie; Satsukawa, Masahiro; Uehara, Shotaro; Shimizu, Makiko; Iwasaki, Kazuhide; Iwano, Shunsuke; Uno, Yasuhiro; Yamazaki, Hiroshi

2015-12-01

Cynomolgus monkeys are used widely in preclinical studies as non-human primate species. The amino acid sequence of cynomolgus monkey cytochrome P450 (P450 or CYP) 2C19 is reportedly highly correlated to that of human CYP2C19 (92%) and CYP2C9 (93%). In the present study, 89 commercially available compounds were screened to find potential substrates for cynomolgus monkey CYP2C19. Of 89 drugs, 34 were metabolically depleted by cynomolgus monkey CYP2C19 with relatively high rates. Among them, 30 compounds have been reported as substrates or inhibitors of, either or both, human CYP2C19 and CYP2C9. Several compounds, including loratadine, showed high selectivity to cynomolgus monkey CYP2C19, and all of these have been reported as human CYP2C19 and/or CYP2C9 substrates. In addition, cynomolgus monkey CYP2C19 formed the same loratadine metabolite as human CYP2C19, descarboethoxyloratadine. These results suggest that cynomolgus monkey CYP2C19 is generally similar to human CYP2C19 and CYP2C9 in its substrate recognition functionality. Copyright © 2015 John Wiley & Sons, Ltd.

The effects of commercial preparations of herbal supplements commonly used by women on the biotransformation of fluorogenic substrates by human cytochromes P450.

PubMed

Ho, Shirley H Y; Singh, Mohini; Holloway, Alison C; Crankshaw, Denis J

2011-07-01

The study set out to determine the potential for commercially available preparations of black cohosh (Actaea racemosa), chaste tree berry (Vitex agnus-castus), crampbark (Viburnum opulus) and false unicorn (Chamaelirium luteum) to inhibit the major human drug metabolizing enzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 as well as CYP1A1 which activates some carcinogens. In vitro microplate-based assays using cDNA-expressed CYP450 isoforms and fluorogenic substrates were used. Components of the commercial herbal preparations interfered with the assays and limited the concentration ranges that could be tested. Nevertheless, the fluorogenic assays were robust, reproducible and easy to perform and thus are still useful for initial screening for potential herb-drug interactions. None of the preparations affected CYPs 1A1 or 2C9 at the concentrations tested but all preparations inhibited some of the enzymes with potencies around 1 μg/mL. The three most potent interactions were: chaste tree berry and CYP2C19 (IC₅₀) 0.22 μg/mL); chaste tree berry and CYP3A4 (IC₅₀) 0.3 μg/mL); black cohosh and CYP2C19 (IC₅₀) 0.37 μg/mL,). Thus, the study successfully identified the potential for the commercial herbal preparations to inhibit human drug metabolizing enzymes. Whether this potential translates into clinically significant herb-drug interactions can only be confirmed by appropriate in vivo studies. Copyright © 2011 John Wiley & Sons, Ltd.

The Effect of Vinpocetine on Human Cytochrome P450 Isoenzymes by Using a Cocktail Method.

PubMed

Kong, Lingti; Song, Chunli; Ye, Linhu; Guo, Daohua; Yu, Meiling; Xing, Rong

2016-01-01

Vinpocetine is a derivative of the alkaloid vincamine, which had been prescribed for chronic cerebral vascular ischemia and acute ischemic stroke or used as a dietary supplement for its several different mechanisms of biological activities. However, information on the cytochrome P450 (CYP) enzyme-mediated drug metabolism has not been previously studied. The present study was performed to investigate the effects of vinpocetine on CYPs activity, and cocktail method was used, respectively. To evaluate the effects of vinpocetine on the activity of human CYP3A4, CYP2C9, CYP2C19, CYP2D6, and CYP2E1, human liver microsomes were utilized to incubate with the mixed CYPs probe substrates and the target components. The results indicate that vinpocetine exhibited weak inhibitory effect on the CYP2C9, where the IC50 value is 68.96 μM, whereas the IC50 values for CYP3A4, CYP2C19, CYP2D6, and CYP2E1 were all over range of 100 μM, which showed that vinpocetine had no apparent inhibitory effects on these CYPs. In conclusion, the results indicated that drugs metabolized by CYP2C9 coadministrated with vinpocetine may require attention or dose adjustment.

The Effect of Vinpocetine on Human Cytochrome P450 Isoenzymes by Using a Cocktail Method

PubMed Central

Kong, Lingti; Song, Chunli; Ye, Linhu; Guo, Daohua; Yu, Meiling; Xing, Rong

2016-01-01

Vinpocetine is a derivative of the alkaloid vincamine, which had been prescribed for chronic cerebral vascular ischemia and acute ischemic stroke or used as a dietary supplement for its several different mechanisms of biological activities. However, information on the cytochrome P450 (CYP) enzyme-mediated drug metabolism has not been previously studied. The present study was performed to investigate the effects of vinpocetine on CYPs activity, and cocktail method was used, respectively. To evaluate the effects of vinpocetine on the activity of human CYP3A4, CYP2C9, CYP2C19, CYP2D6, and CYP2E1, human liver microsomes were utilized to incubate with the mixed CYPs probe substrates and the target components. The results indicate that vinpocetine exhibited weak inhibitory effect on the CYP2C9, where the IC50 value is 68.96 μM, whereas the IC50 values for CYP3A4, CYP2C19, CYP2D6, and CYP2E1 were all over range of 100 μM, which showed that vinpocetine had no apparent inhibitory effects on these CYPs. In conclusion, the results indicated that drugs metabolized by CYP2C9 coadministrated with vinpocetine may require attention or dose adjustment. PMID:27006677

An in vitro evaluation of cytochrome P450 inhibition and P-glycoprotein interaction with goldenseal, Ginkgo biloba, grape seed, milk thistle, and ginseng extracts and their constituents.

PubMed

Etheridge, Amy S; Black, Sherry R; Patel, Purvi R; So, James; Mathews, James M

2007-07-01

Drug-herb interactions can result from the modulation of the activities of cytochrome P450 (P450) and/or drug transporters. The effect of extracts and individual constituents of goldenseal, Ginkgo biloba (and its hydrolyzate), grape seed, milk thistle, and ginseng on the activities of cytochrome P450 enzymes CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and CYP3A4 in human liver microsomes were determined using enzyme-selective probe substrates, and their effect on human P-glycoprotein (Pgp) was determined using a baculovirus expression system by measuring the verapamil-stimulated, vanadate-sensitive ATPase activity. Extracts were analyzed by HPLC to standardize their concentration(s) of constituents associated with the pharmacological activity, and to allow comparison of their effects on P450 and Pgp with literature values. Many of the extracts/constituents exerted > or = 50 % inhibition of P450 activity. These include those from goldenseal (normalized to alkaloid content) inhibiting CYP2C8, CYP2D6, and CYP3A4 at 20 microM, ginkgo inhibiting CYP2C8 at 10 microM, grape seed inhibiting CYP2C9 and CYP3A4 at 10 microM, milk thistle inhibiting CYP2C8 at 10 microM, and ginsenosides F1 and Rh1 (but not ginseng extract) inhibiting CYP3A4 at 10 microM. Goldenseal extracts/constituents (20 microM, particularly hydrastine) and ginsenoside Rh1 stimulated ATPase at about half of the activity of the model substrate, verapamil (20 microM). The data suggest that the clearance of a variety of drugs may be diminished by concomitant use of these herbs via inhibition of P450 enzymes, but less so by Pgp-mediated effects.

Association of Cytochrome P450 Genetic Variants with Clopidogrel Resistance and Outcomes in Acute Ischemic Stroke

PubMed Central

Yi, Xingyang; Wang, Yanfen; Zhou, Qiang; Wang, Chun; Cheng, Wen; Chi, Lifen

2016-01-01

Aims: Clopidogrel is an antiplatelet drug primarily used to treat or prevent acute ischemic stroke (IS) or myocardial infarction (MI). This prodrug requires biotransformation to an active metabolite by cytochrome P450 (CYP) enzymes, and CYP single nucleotide polymorphisms (SNPs) could affect the efficiency of such biotransformation. Methods: A total of 375 consecutive IS patients were genotyped for eight CYP SNPs using mass spectrometry. Platelet aggregation activity was measured before and after the 7 – 10 day treatment. Gene–gene interactions were analyzed using generalized multifactor dimensionality reduction (GMDR) analysis. All patients received clopidogrel therapy and were followed up for six months. Primary outcomes were evaluated as a composite of recurrent ischemic stroke (RIS), MI, and death. The secondary outcome was the modified Rankin Scale (mRS). Results: Clopidogrel resistance occurred in 153 patients (40.8%). The frequency of CYP3A5 (rs776746) GG/AG and CYP2C19*2 (rs4244285) AA/AG genotypes was significantly higher in clopidogrel-resistant patients than in sensitive patients. There was a significant gene-gene interaction between CYP3A5 (rs776746) and CYP2C19*2 (rs4244285). CYP2C19*2 AA and its interaction with CYP3A5 GG were independent predictors of clopidogrel resistance and affected the activity of platelet aggregation. Diabetes mellitus, CYP2C19*2 (rs4244285), clopidogrel resistance, and the interaction of CYP2C19*2 with CYP3A5 were all independent risk factors for the primary outcomes of clopidogrel treatment. Clopidogrel-resistant patients were more likely to have poor outcomes (mRS > 2 points) compared with clopidogrel-sensitive patients. Conclusion: CYP SNPs and their interactions are associated with drug resistance and outcomes in acute IS patients. PMID:26961113

Effects of clopidogrel on the pharmacokinetics of sibutramine and its active metabolites.

PubMed

Bae, Jung-Woo; Jang, Choon-Gon; Lee, Seok-Young

2011-12-01

Sibutramine is metabolized by the enzymes CYP2B6 and CYP2C19 into 2 active metabolites, M1 (mono-desmethyl sibutramine) and M2 (di-desmethyl sibutramine). Clopidogrel is a mechanism-based inhibitor of CYP2B6 and CYP2C19. In this study, 13 extensive metabolizers of CYP2B6 and CYP2C19 were evaluated to clarify whether clopidogrel inhibits the formation of the active metabolites of sibutramine. In the control phase, each subject received a 15-mg oral dose of sibutramine. After a washout period of 2 weeks, in the clopidogrel phase, the subjects received 300 mg of clopidogrel on the first day and then 75-mg once daily for 6 days. One hour after the last dosing of clopidogrel, all subjects received 15-mg of sibutramine. Compared with the control phase, the mean sibutramine and M1 plasma concentrations were higher after clopidogrel treatment. Clopidogrel significantly increased the half-life (242% of control phase) and area under the plasma concentration-time curve from 0 to infinity (AUC(inf)) (227% of control phase) of sibutramine and decreased the apparent oral clearance (31% of control phase) of sibutramine. Pharmacokinetic analysis showed significant increases in the AUC(inf) (162% of control phase) of M1. The CYP2B6 and CYP2C19 inhibitor clopidogrel significantly inhibited the formations of M1 from sibutramine and M2 from sibutramine by 37% and 64%, respectively. Therefore, CYP2B6 and CYP2C19 are in vivo catalysts for the formation of the 2 active metabolites of sibutramine.

The relevance of chemical interactions with CYP17 enzyme activity: Assessment using a novel in vitro assay

DOE Office of Scientific and Technical Information (OSTI.GOV)

Roelofs, Maarke J.E., E-mail: m.j.e.roelofs@uu.nl; Center for Health Protection, National Institute for Public Health and the Environment; Piersma, Aldert H.

The steroidogenic cytochrome P450 17 (CYP17) enzyme produces dehydroepiandrosterone (DHEA), which is the most abundant circulating endogenous sex steroid precursor. DHEA plays a key role in e.g. sexual functioning and development. To date, no rapid screening assay for effects on CYP17 is available. In this study, a novel assay using porcine adrenal cortex microsomes (PACMs) was described. Effects of twenty-eight suggested endocrine disrupting compounds (EDCs) on CYP17 activity were compared with effects in the US EPA validated H295R (human adrenocorticocarcinoma cell line) steroidogenesis assay. In the PACM assay DHEA production was higher compared with the H295R assay (4.4 versus 2.2more » nmol/h/mg protein). To determine the additional value of a CYP17 assay, all compounds were also tested for interaction with CYP19 (aromatase) using human placental microsomes (HPMs) and H295R cells. 62.5% of the compounds showed enzyme inhibition in at least one of the microsomal assays. Only the cAMP inducer forskolin induced CYP17 activity, while CYP19 was induced by four test compounds in the H295R assay. These effects remained unnoticed in the PACM and HPM assays. Diethylstilbestrol and tetrabromobisphenol A inhibited CYP17 but not CYP19 activity, indicating different mechanisms for the inhibition of these enzymes. From our results it becomes apparent that CYP17 can be a target for EDCs and that this interaction differs from interactions with CYP19. Our data strongly suggest that research attention should focus on validating a specific assay for CYP17 activity, such as the PACM assay, that can be included in the EDC screening battery. - Highlights: ► DHEA, produced by CYP17, plays a key role in sexual functioning and development. ► No rapid screening assay for effects on CYP17 is available yet. ► A novel assay using porcine adrenal cortex microsomes (PACMs) was described. ► Endocrine disrupting compounds (EDCs) targeting CYP17 interact differently with CYP19. ► A specific CYP17 assay is a valuable screening for effects early in steroidogenesis.« less

Metabolic profiling of five flavonoids from Dragon's Blood in human liver microsomes using high-performance liquid chromatography coupled with high resolution mass spectrometry.

PubMed

Li, Yujuan; Zhang, Yushi; Wang, Rui; Wei, Lizhong; Deng, Yulin; Ren, Wei

2017-05-01

Although much is known about the pharmacological activities of Dragon's Blood (DB, a traditional Chinese herb), its metabolism in human liver microsomes (HLMs) and the cytochrome P450 (CYP) enzymes has not been studied. This study aims to identify the metabolic profile of five flavonoids (loureirin A, loureirin B, loureirin C, 7,4'-dihydroxyflavone and 5,7,4'-trihydroxyflavanone) from DB in HLMs as well as the CYP enzymes that are involved in the metabolism of them. High-resolution mass spectrometry was used to characterize the structures of their metabolites and 10 cDNA-expressed CYP enzymes (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4 and CYP3A5) were used to verify which isozymes mediate in the metabolism of the metabolites. Totally, 29 metabolites including 10 metabolites of loureirin A, 10 metabolites of loureirin B, 4 metabolites of loureirin C, 2 metabolites of 7,4'-dihydroxyflavone and 3 metabolites of 5,7,4'-trihydroxyflavanone were elucidated and identified on the basis of the high-resolution MS n data. The metabolic profile of the five flavonoids in HLMs involved hydroxylation, oxidation and demethylation. Among them, hydroxylation was the predominant biotransformation of the five flavonoids in HLMs, occurring in combination with other metabolic reactions. Assay with recombinant P450s revealed that CYP2C9 and CYP2C19 played an important role in the hydroxylation of flavonoids in HLMs. To the best of our knowledge, this is the first in vitro evaluation of the metabolic profile of loureirin A, loureirin B, loureirin C, 7,4'-dihydroxyflavone and 5,7,4'-trihydroxyflavanone in HLMs. Copyright © 2017 Elsevier B.V. All rights reserved.

Mechanism-based inactivation of CYP2C9 by linderane.

PubMed

Wang, Hui; Wang, Kai; Mao, Xu; Zhang, Qingqing; Yao, Tong; Peng, Ying; Zheng, Jiang

2015-01-01

1. Linderane (LDR), a furan-containing sesquiterpenoid, is found in Lindera aggregata (Sims) Kosterm, a common traditional Chinese herbal medicine. We thoroughly studied the irreversible inhibitory effect of LDR on cytochrome P450 2C9 (CYP2C9). 2. LDR caused a time- and concentration-dependent inactivation of CYP2C9. In addition, the inactivation of CYP2C9 by LDR was NADPH-dependent and irreversible. More than 50% of CYP2C9 activity was lost after its incubation with LDR at the concentration of 10 μM for 15 min at 30 °C. The maximal rate constant for inactivation (kinact) was found to be 0.0419 min(-1), and the concentration required for half-maximal inactivation (KI) was 1.26 μM, respectively. Glutathione (GSH), catalase, and superoxide dismutase (SOD) failed to protect CYP2C9 against inactivation by LDR. Diclofenac, a substrate of CYP2C9, prevented the enzyme from inactivation produced by LDR. The estimated partition ratio of the inactivation was approximately 227. 3. Two reactive intermediates, including furanoepoxide and γ-ketoenal, might be responsible for the observed enzyme inactivation. The formation of the intermediates was verified by chemical synthesis. Multiple P450 enzymes, including CYPs 1A2, 2B6, 2C9, 2C19, 2D6, 3A4, and 3A5, were found to be involved in the metabolic activation of LDR. In conclusion, LDR was characterized as a mechanism-based inactivator of CYP2C9.

Inhibition of drug metabolizing cytochrome P450s by the aromatase inhibitor drug letrozole and its major oxidative metabolite 4,4′-methanol-bisbenzonitrile in vitro

PubMed Central

Jeong, Seongwook; Woo, Margaret M.; Flockhart, David A.

2009-01-01

Purpose To determine the inhibitory potency of letrozole and its main human metabolite, 4,4′-methanol-bisbenzonitrilee, on the activities of eight cytochrome P450 (CYP) enzymes. Methods Letrozole and its metabolite were incubated with human liver microsomes (HLMs) (or expressed CYP isoforms) and NADPH in the absence (control) and presence of the test inhibitor. Results Letrozole was a potent competitive inhibitor of CYP2A6 (Ki 4.6 ± 0.05 μM and 5.0 ± 2.4 μM in HLMs and CYP2A6, respectively) and a weak inhibitor of CYP2C19 (Ki 42.2 μM in HLMs and 33.3 μM in CYP2C19), while its metabolite showed moderate inhibition of CYP2C19 and CYP2B6. Letrozole or its metabolite had negligible effect on other CYPs. Conclusions Based on the in vitro Ki values, letrozole is predicted to be a weak inhibitor of CYP2A6 in vivo. Letrozole and its major human metabolite show inhibitory activity towards other CYPs, but clinically relevant drug interactions seem less likely as the Ki values are above the therapeutic plasma concentrations of letrozole. PMID:19198839

Comprehensive Evaluation for Substrate Selectivity of Cynomolgus Monkey Cytochrome P450 2C9, a New Efavirenz Oxidase.

PubMed

Hosaka, Shinya; Murayama, Norie; Satsukawa, Masahiro; Uehara, Shotaro; Shimizu, Makiko; Iwasaki, Kazuhide; Iwano, Shunsuke; Uno, Yasuhiro; Yamazaki, Hiroshi

2015-07-01

Cynomolgus monkeys are widely used as primate models in preclinical studies, because of their evolutionary closeness to humans. In humans, the cytochrome P450 (P450) 2C enzymes are important drug-metabolizing enzymes and highly expressed in livers. The CYP2C enzymes, including CYP2C9, are also expressed abundantly in cynomolgus monkey liver and metabolize some endogenous and exogenous substances like testosterone, S-mephenytoin, and diclofenac. However, comprehensive evaluation regarding substrate specificity of monkey CYP2C9 has not been conducted. In the present study, 89 commercially available drugs were examined to find potential monkey CYP2C9 substrates. Among the compounds screened, 20 drugs were metabolized by monkey CYP2C9 at a relatively high rates. Seventeen of these compounds were substrates or inhibitors of human CYP2C9 or CYP2C19, whereas three drugs were not, indicating that substrate specificity of monkey CYP2C9 resembled those of human CYP2C9 or CYP2C19, with some differences in substrate specificities. Although efavirenz is known as a marker substrate for human CYP2B6, efavirenz was not oxidized by CYP2B6 but by CYP2C9 in monkeys. Liquid chromatography-mass spectrometry analysis revealed that monkey CYP2C9 and human CYP2B6 formed the same mono- and di-oxidized metabolites of efavirenz at 8 and 14 positions. These results suggest that the efavirenz 8-oxidation could be one of the selective markers for cynomolgus monkey CYP2C9 among the major three CYP2C enzymes tested. Therefore, monkey CYP2C9 has the possibility of contributing to limited specific differences in drug oxidative metabolism between cynomolgus monkeys and humans. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Identification and in silico prediction of metabolites of the model compound, tebufenozide by human CYP3A4 and CYP2C19.

PubMed

Shirotani, Naoki; Togawa, Moe; Ikushiro, Shinichi; Sakaki, Toshiyuki; Harada, Toshiyuki; Miyagawa, Hisashi; Matsui, Masayoshi; Nagahori, Hirohisa; Mikata, Kazuki; Nishioka, Kazuhiko; Hirai, Nobuhiro; Akamatsu, Miki

2015-10-15

The metabolites of tebufenozide, a model compound, formed by the yeast-expressed human CYP3A4 and CYP2C19 were identified to clarify the substrate recognition mechanism of the human cytochrome P450 (CYP) isozymes. We then determined whether tebufenozide metabolites may be predicted in silico. Hydrogen abstraction energies were calculated with the density functional theory method B3LYP/6-31G(∗). A docking simulation was performed using FRED software. Several alkyl sites of tebufenozide were hydroxylated by CYP3A4 whereas only one site was modified by CYP2C19. The accessibility of each site of tebufenozide to the reaction center of CYP enzymes and the susceptibility of each hydrogen atom for metabolism by CYP enzymes were evaluated by a docking simulation and hydrogen abstraction energy estimation, respectively. Copyright © 2015 Elsevier Ltd. All rights reserved.

P450 oxidoreductase deficiency: a disorder of steroidogenesis with multiple clinical manifestations.

PubMed

Miller, Walter L

2012-10-23

Cytochrome P450 enzymes catalyze the biosynthesis of steroid hormones and metabolize drugs. There are seven human type I P450 enzymes in mitochondria and 50 type II enzymes in endoplasmic reticulum. Type II enzymes, including both drug-metabolizing and some steroidogenic enzymes, require electron donation from a two-flavin protein, P450 oxidoreductase (POR). Although knockout of the POR gene causes embryonic lethality in mice, we discovered human POR deficiency as a disorder of steroidogenesis associated with the Antley-Bixler skeletal malformation syndrome and found mild POR mutations in phenotypically normal adults with infertility. Assay results of mutant forms of POR using the traditional but nonphysiologic assay (reduction of cytochrome c) did not correlate with patient phenotypes; assays based on the 17,20 lyase activity of P450c17 (CYP17) correlated with clinical phenotypes. The POR sequence in 842 normal individuals revealed many polymorphisms; amino acid sequence variant A503V is encoded by ~28% of human alleles. POR A503V has about 60% of wild-type activity in assays with CYP17, CYP2D6, and CYP3A4, but nearly wild-type activity with P450c21, CYP1A2, and CYP2C19. Activity of a particular POR variant with one P450 enzyme will not predict its activity with another P450 enzyme: Each POR-P450 combination must be studied individually. Human POR transcription, initiated from an untranslated exon, is regulated by Smad3/4, thyroid receptors, and the transcription factor AP-2. A promoter polymorphism reduces transcription to 60% in liver cells and to 35% in adrenal cells. POR deficiency is a newly described disorder of steroidogenesis, and POR variants may account for some genetic variation in drug metabolism.

Severe tremor after cotrimoxazole-induced elevation of venlafaxine serum concentrations in a patient with major depressive disorder.

PubMed

Geber, Christian; Ostad Haji, Elnaz; Schlicht, Konrad; Hiemke, Christoph; Tadić, André

2013-06-01

: We describe a female patient who was an extensive metabolizer of cytochrome P450 isoenzyme (CYP) 2D6 and an intermediate metabolizer of CYP2C19 (genotype: CYP2C19 *1/*2). She exhibited high serum concentrations of venlafaxine and O-desmethylvenlafaxine and developed severe tremor after comedication with cotrimoxazole (sulfamethazole/trimethoprim). Venlafaxine is mainly metabolized by O- and N-demethylation. O-demethylation is catalyzed by the highly polymorphic CYP2D6 and N-demethylation by several enzymes, CYP2C19, CYP2C9, and CYP3A4. The observed overall pharmacokinetic effect was most probably the result of decreased N-demethylation of venlafaxine by (1) reduced expression of CYP2C19 due to a genetic deficit and (2) inhibition of CYP2C9 by cotrimoxazole.

Functional polymorphisms in the CYP2C19 gene contribute to digestive system cancer risk: evidence from 11,042 subjects.

PubMed

Zhou, Bo; Song, Zhenshun; Qian, Mingping; Li, Liang; Gong, Jian; Zou, Shaowu

2013-01-01

CYP2C19 belongs to the cytochrome P450 superfamily of enzymes involved in activating and detoxifying many carcinogens and endogenous compounds, which has attracted considerable attention as a candidate gene for digestive system cancer. CYP2C19 has two main point mutation sites (CYP2C19*2, CYP2C19*3) leading to poor metabolizer (PM) phenotype. In the past decade, the relationship between CYP2C19 polymorphism and digestive system cancer has been reported in various ethnic groups; however, these studies have yielded contradictory results. To clarify this inconsistency, we performed this meta-analysis. Databases including Pubmed, EMBASE, Web of Science and China National Knowledge Infrastructure (CNKI) were searched to find relevant studies. Odds ratios (ORs) with 95% confidence intervals (CIs) were used to assess the strength of association. In total, 18 studies with 4,414 cases and 6,628 controls were included. Overall, significantly elevated digestive system cancer risk was associated CYP2C19 PM with OR of 1.66 (95%CI: 1.31-2.10, P<10(-5)) when all studies were pooled into the meta-analysis. There was strong evidence of heterogeneity (P = 0.006), which largely disappeared after stratification by cancer type. In the stratified analyses according to cancer type, ethnicity, control source and sample size, significantly increased risks were found. In summary, our meta-analysis suggested that the PM phenotype caused by the variation on CYP2C19 gene is associated with increased risk of digestive system cancer, especially in East Asians.

Investigation of drug-drug interactions caused by human pregnane X receptor-mediated induction of CYP3A4 and CYP2C subfamilies in chimeric mice with a humanized liver.

PubMed

Hasegawa, Maki; Tahara, Harunobu; Inoue, Ryo; Kakuni, Masakazu; Tateno, Chise; Ushiki, Junko

2012-03-01

The induction of cytochrome P450 (P450) enzymes is one of the risk factors for drug-drug interactions (DDIs). To date, the human pregnane X receptor (PXR)-mediated CYP3A4 induction has been well studied. In addition to CYP3A4, the expression of CYP2C subfamily is also regulated by PXR, and the DDIs caused by the induction of CYP2C enzymes have been reported to have a major clinical impact. The purpose of the present study was to investigate whether chimeric mice with a humanized liver (PXB mice) can be a suitable animal model for investigating the PXR-mediated induction of CYP2C subfamily, together with CYP3A4. We evaluated the inductive effect of rifampicin (RIF), a typical human PXR ligand, on the plasma exposure to the four P450 substrate drugs (triazolam/CYP3A4, pioglitazone/CYP2C8, (S)-warfarin/CYP2C9, and (S)-(-)-mephenytoin/CYP2C19) by cassette dosing in PXB mice. The induction of several drug-metabolizing enzymes and transporters in the liver was also examined by measuring the enzyme activity and mRNA expression levels. Significant reductions in the exposure to triazolam, pioglitazone, and (S)-(-)-mephenytoin, but not to (S)-warfarin, were observed. In contrast to the in vivo results, all the four P450 isoforms, including CYP2C9, were elevated by RIF treatment. The discrepancy in the (S)-warfarin results between in vivo and in vitro studies may be attributed to the relatively small contribution of CYP2C9 to (S)-warfarin elimination in the PXB mice used in this study. In summary, PXB mice are a useful animal model to examine DDIs caused by PXR-mediated induction of CYP2C and CYP3A4.

CYP2C19*2 status in patients with Stevens-Johnson syndrome and toxic epidermal necrolysis

PubMed Central

Laska, Amanda J; Han, Marie J; Lospinoso, Josh A; Brown, Patrick J; Beachkofsky, Thomas M

2017-01-01

Purpose Genetic polymorphisms have been linked to an increased predisposition to developing certain diseases. For example, patients of Han-Chinese descent carrying the HLA-B*1502 allele are at an increased risk of developing Stevens-Johnson syndrome and toxic epidermal necrolysis (SJS/TEN) if given carbamazepine. Given the complexity of in vivo drug metabolism, it is plausible that the activity of enzyme systems unrelated to specific drug metabolism may be important. Although multiple biomarkers have been identified in unique ethnic groups, there has yet to be a study investigating the presence of the slow metabolizing allele of CYP2C19, denoted CYP2C19*2, in diverse groups and the risk of developing SJS/TEN. Patients and methods This study looked into the carrier status of CYP2C19*2, a poor metabolizing variant of CYP2C19, in patients diagnosed with SJS/TEN. We looked at its status in our series as a whole and when patients were divided by ethnicity. Genomic DNA was extracted from formalin-fixed paraffin-embedded tissue of patients with biopsy-proven SJS/TEN and real-time polymerase chain reaction was used to assess for the presence of CYP2C19*2. Results CYP2C19*2 status was determined in 47 patients. Twenty-nine of these 47 patients had a single medication implicated as causing their disease, and eight of these patients were heterozygous or homozygous for CYP2C19*2. There was insufficient evidence to conclude that the presence of CYP2C19*2 is an independent predictor of risk for developing SJS/TEN in our series as a whole. This analysis also confirmed that the frequency of the CYP2C19*2 polymorphism within the different ethnicities in our series did not vary statistically from reported ethnic rates. Conclusion Our study was unable to show a relationship between CYP2C19*2 status and predisposition toward SJS/TEN. We had a heterogeneous population, making it difficult to control for possible confounding factors. PMID:28553132

Modulation of CYPs, P-gp, and PXR by Eschscholzia californica (California Poppy) and Its Alkaloids.

PubMed

Manda, Vamshi K; Ibrahim, Mohamed A; Dale, Olivia R; Kumarihamy, Mallika; Cutler, Stephen J; Khan, Ikhlas A; Walker, Larry A; Muhammad, Ilias; Khan, Shabana I

2016-04-01

Eschscholzia californica, a native US plant, is traditionally used as a sedative, analgesic, and anxiolytic herb. With the rapid rise in the use of herbal supplements together with over-the-counter and prescription drugs, the risk for potential herb-drug interactions is also increasing. Most of the clinically relevant pharmacokinetic drug interactions occur due to modulation of cytochrome P450 enzymes (CYPs), P-glycoprotein, and the pregnane X receptor by concomitantly used herbs. This study aimed to determine the effects of an EtOH extract, aqueous extract (tea), basic CHCl3 fractions, and isolated major alkaloids, namely protopine (1), escholtzine (2), allocryptopine (3), and californidine (4), of E. californica on the activity of cytochrome P450s, P-glycoprotein and the pregnane X receptor. The EtOH extract and fractions showed strong time-dependent inhibition of CYP 3A4, CYP 2C9, and CYP 2C19, and reversible inhibition of CYP 2D6. Among the alkaloids, escholtzine (2) and allocryptopine (3) exhibited time-dependent inhibition of CYP 3A4, CYP 2C9, and CYP 2C19 (IC50 shift ratio > 2), while protopine (1) and allocryptopine (3) showed reversible inhibition of CYP 2D6 enzyme. A significant activation of the pregnane X receptor (> 2-fold) was observed with the EtOH extract, basic CHCl3 fraction, and alkaloids (except protopine), which resulted into an increased expression of mRNA and the activity of CYP 3A4 and CYP 1A2. The expression of P-glycoprotein was unaffected. However, aqueous extract (tea) and its main alkaloid californidine (4) did not affect cytochrome P450s, P-glycoprotein, or the pregnane X receptor. This data suggests that EtOH extract of E. californica and its major alkaloids have a potential of causing interactions with drugs that are metabolized by cytochrome P450s, while the tea seems to be safer. Georg Thieme Verlag KG Stuttgart · New York.

HepaRG human hepatic cell line utility as a surrogate for primary human hepatocytes in drug metabolism assessment in vitro.

PubMed

Lübberstedt, Marc; Müller-Vieira, Ursula; Mayer, Manuela; Biemel, Klaus M; Knöspel, Fanny; Knobeloch, Daniel; Nüssler, Andreas K; Gerlach, Jörg C; Zeilinger, Katrin

2011-01-01

Primary human hepatocytes are considered as a highly predictive in vitro model for preclinical drug metabolism studies. Due to the limited availability of human liver tissue for cell isolation, there is a need of alternative cell sources for pharmaceutical research. In this study, the metabolic activity and long-term stability of the human hepatoma cell line HepaRG were investigated in comparison to primary human hepatocytes (pHH). Hepatocyte-specific parameters (albumin and urea synthesis, galactose and sorbitol elimination) and the activity of human-relevant cytochrome P450 (CYP) enzymes (CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) were assayed in both groups over a period of 14 days subsequently to a two week culture period in differentiated state in case of the HepaRG cells, and compared with those of cryopreserved hepatocytes in suspension. In addition, the inducibility of CYP enzymes and the intrinsic clearances of eleven reference drugs were determined. The results show overall stable metabolic activity of HepaRG cells over the monitored time period. Higher albumin production and galactose/sorbitol elimination rates were observed compared with pHH, while urea production was not detected. CYP enzyme-dependent drug metabolic capacities were shown to be stable over the cultivation time in HepaRG cells and were comparable or even higher (CYP2C9, CYP2D6, CYP3A4) than in pHH, whereas commercially available hepatocytes showed a different pattern The intrinsic clearance rates of reference drugs and enzyme induction of most CYP enzymes were similar in HepaRG cells and pHH. CYP1A2 activity was highly inducible in HepaRG by β-naphthoflavone. In conclusion, the results from this study indicate that HepaRG cells could provide a suitable alternative to pHH in pharmaceutical research and development for metabolism studies such as CYP induction or sub-chronic to chronic hepatotoxicity studies. Copyright © 2010 Elsevier Inc. All rights reserved.

Metabolism of 18-methoxycoronaridine, an ibogaine analog, to 18-hydroxycoronaridine by genetically variable CYP2C19.

PubMed

Zhang, Wenjiang; Ramamoorthy, Yamini; Tyndale, Rachel F; Glick, Stanley D; Maisonneuve, Isabelle M; Kuehne, Martin E; Sellers, Edward M

2002-06-01

18-Methoxycoronaridine, a newly developed ibogaine analog, has been reported to decrease the self-administration of morphine, cocaine, ethanol, and nicotine. It has also been reported to attenuate naltrexone-precipitated signs of morphine withdrawal. In this study, three metabolites of 18-methoxycoronaridine (18-MC) were separated and identified by high-performance liquid chromatography-electrospray ionization-mass spectrometry-mass spectrometry (HPLC-ESI-MS-MS); the major metabolite was 18-hydroxycoronaridine (18-HC). The other two metabolites were elucidated as hydroxylated metabolites on the basis of their MS-MS spectra. Catalytic studies of 18-MC O-demethylase activity in human liver microsomes indicate that one high affinity enzyme is involved in this reaction (K(m) from 2.81 to 7.9 microM; V(max) from 0.045 to 0.29 nmol/mg/min). In cDNA-expressing microsomes, only CYP2C19 displayed significant 18-MC O-demethylase activity (K(m) 1.34 microM; V(max) 0.21 nmol/mg/min). S-Mephenytoin, a selective CYP2C19 inhibitor, inhibited 18-MC O-demethylation by 65% at a concentration of 2 times its K(I), and antibodies against rat 2C (human CYP2C8, 2C9, 2C19) inhibited 18-HC formation by 70%. Studies with other cytochrome P450 (P450)-selective chemical inhibitors and antibodies failed to demonstrate an appreciable role for other P450s in this reaction. In addition, in microsomes from five different human livers, 18-MC O-demethylation correlated with S-mephenytoin 4'hydroxylase activity but not with other P450 probe reactions. These data indicate that 18-HC formation is the predominant pathway of 18-MC metabolism in vitro in human liver microsomes and that this metabolic pathway is primarily catalyzed by the polymorphic CYP2C19. The apparent selectivity of this pathway for CYP2C19 suggests 18-MC as a potentially useful probe of CYP2C19 activity in vitro and in vivo.

Characterisation of the cytochrome P450 enzymes involved in the in vitro metabolism of granisetron.

PubMed Central

Bloomer, J C; Baldwin, S J; Smith, G J; Ayrton, A D; Clarke, S E; Chenery, R J

1994-01-01

1. The metabolism of granisetron was investigated in human liver microsomes to identify the specific forms of cytochrome P450 responsible. 2. 7-hydroxy and 9'-desmethyl granisetron were identified as the major products of metabolism following incubation of granisetron with human liver microsomes. At low, clinically relevant, concentrations of granisetron the 7-hydroxy metabolite predominated. Rates of granisetron 7-hydroxylation varied over 100-fold in the human livers investigated. 3. Enzyme kinetics demonstrated the involvement of at least two enzymes contributing to the 7-hydroxylation of granisetron, one of which was a high affinity component with a Km of 4 microM. A single, low affinity, enzyme was responsible for the 9'-desmethylation of granisetron. 4. Granisetron caused no inhibition of any of the cytochrome P450 activities investigated (CYP1A2, CYP2A6, CYP2B6, CYP2C9/8, CYP2C19, CYP2D6, CYP2E1 and CYP3A), at concentrations up to 250 microM. 5. Studies using chemical inhibitors selective for individual P450 enzymes indicated the involvement of cytochrome P450 3A (CYP3A), both pathways of granisetron metabolism being very sensitive to ketoconazole inhibition. Correlation data were consistent with the role of CYP3A3/4 in granisetron 9'-desmethylation but indicated that a different enzyme was involved in the 7-hydroxylation. PMID:7888294

Inhibitory effects of kale ingestion on metabolism by cytochrome P450 enzymes in rats.

PubMed

Yamasaki, Izumi; Yamada, Masayoshi; Uotsu, Nobuo; Teramoto, Sachiyuki; Takayanagi, Risa; Yamada, Yasuhiko

2012-01-01

Kale (Brassica oleracea L. var acephala DC) is a leafy green vegetable belonging to the cabbage family (Brassicaceae) that contains a large amount of health-promoting phytochemicals. There are any reports about the effects of kale ingestion on the chemoprevention function and mechanism, but the interactions between kale and drugs have not been researched. We investigated the effects of kale intake on cytochrome P450 (CYP) metabolism by using cocktail probe drugs, including midazolam (for CYP3A4), caffeine (for CYP1A2), dextromethorphan (for CYP2D6), tolbutamide (for CYP2C9), omeprazole (for CYP2C19), and chlorzoxazone (for CYP2E1). Cocktail drugs were administered into rats treated with kale and cabbage (2000 mg/kg) for a week. The results showed that kale intake induced a significant increase in plasma levels and the AUC of midazolam, caffeine, and dextromethorphan. In addition, the plasma concentration and AUC of omeprazole tended to increase. Additionally, no almost differences in the mRNA expression levels of CYP enzymes in the liver were observed. In conclusion, kale ingestion was considered to have an inhibitory effect on the activities of CYP3A4, 1A2, 2D6, and 2C19 for a reason competitive inhibition than inhibitory changes in the mRNA expressions.

In vitro metabolism and drug interaction potential of a new highly potent anti-cytomegalovirus molecule, CMV423 (2-chloro 3-pyridine 3-yl 5,6,7,8-tetrahydroindolizine 1-carboxamide)

PubMed Central

Bournique, Bruno; Lambert, Nicole; Boukaiba, Rachid; Martinet, Michel

2001-01-01

Aims To identify the enzymes involved in the metabolism of CMV423, a new anticytomegalovirus molecule, to evaluate its in vitro clearance and to investigate its potential involvement in drug/drug interactions that might occur in the clinic. Methods The enzymes involved in and the kinetics of CMV423 biotransformation were determined using pools of human liver subcellular fractions and heterologously expressed human cytochromes P450 (CYP) and FMO. The effect of CMV423 on CYP probe activities as well as on indinavir and AZT metabolism was determined, and 26 drugs were tested for their potential to inhibit or activate CMV423 metabolism. Results CMV423 was oxidized by CYP and not by FMO or cytosolic enzymes. The Km values for 8-hydroxylation to rac-RPR 127025, an active metabolite, and subsequent ketone formation by human liver microsomes were 44 ± 13 µm and 47 ± 11 µm, respectively, with corresponding Vmax/Km ratios of 14 and 4 µl min−1 nmol−1 P450. Inhibition with selective CYP inhibitors indicated that CYP1A2 was the main isoform involved, with some participation from CYP3A. Expressed human CYP1A1, 1A2, 2C9, 3A4 and 2C8 catalysed rac-RPR 127025 formation with Km values of < 10 µm, 50 ± 21 µm, 55 ± 19 µm, circa 282 ± 61 µm and circa 1450 µm, respectively. CYP1B1, 2A6, 2B6, 2C19, 2D6, 2E1 or 3A5 did not catalyse the reaction to any detectable extent. CYP1A1 and 3A4 also catalysed ketone formation from rac-RPR 127025. In human liver microsomes, CMV423 at 1 and 10 µm inhibited CYP1A2 activity up to 31% and 63%, respectively, CYP3A4 activity up to 40% (10 µm) and CYP2C9 activity by 35% (1 and 10 µm). No effect was observed on CYP2A6, 2D6 and 2E1 activities. CMV423 had no effect on indinavir and AZT metabolism. Amongst 26 drugs tested, none inhibited CMV423 metabolism in vitro at therapeutic concentrations. Conclusions CMV423 is mainly metabolized by CYP1A2 and 3A4. Its metabolism should not be saturable at the targeted therapeutic concentrations range (Cmax < 1 µm). CMV423 will probably affect CYP1A2 and 1A1 activities in vivo to some extent, but no other drug–drug interactions are expected. PMID:11453890

Estimation of the binding modes with important human cytochrome P450 enzymes, drug interaction potential, pharmacokinetics, and hepatotoxicity of ginger components using molecular docking, computational, and pharmacokinetic modeling studies.

PubMed

Qiu, Jia-Xuan; Zhou, Zhi-Wei; He, Zhi-Xu; Zhang, Xueji; Zhou, Shu-Feng; Zhu, Shengrong

2015-01-01

Ginger is one of the most commonly used herbal medicines for the treatment of numerous ailments and improvement of body functions. It may be used in combination with prescribed drugs. The coadministration of ginger with therapeutic drugs raises a concern of potential deleterious drug interactions via the modulation of the expression and/or activity of drug-metabolizing enzymes and drug transporters, resulting in unfavorable therapeutic outcomes. This study aimed to determine the molecular interactions between 12 main active ginger components (6-gingerol, 8-gingerol, 10-gingerol, 6-shogaol, 8-shogaol, 10-shogaol, ar-curcumene, β-bisabolene, β-sesquiphelandrene, 6-gingerdione, (-)-zingiberene, and methyl-6-isogingerol) and human cytochrome P450 (CYP) 1A2, 2C9, 2C19, 2D6, and 3A4 and to predict the absorption, distribution, metabolism, excretion, and toxicity (ADMET) of the 12 ginger components using computational approaches and comprehensive literature search. Docking studies showed that ginger components interacted with a panel of amino acids in the active sites of CYP1A2, 2C9, 2C19, 2D6, and 3A4 mainly through hydrogen bond formation, to a lesser extent, via π-π stacking. The pharmacokinetic simulation studies showed that the [I]/[Ki ] value for CYP2C9, 2C19, and 3A4 ranged from 0.0002 to 19.6 and the R value ranged from 1.0002 to 20.6 and that ginger might exhibit a high risk of drug interaction via inhibition of the activity of human CYP2C9 and CYP3A4, but a low risk of drug interaction toward CYP2C19-mediated drug metabolism. Furthermore, it has been evaluated that the 12 ginger components possessed a favorable ADMET profiles with regard to the solubility, absorption, permeability across the blood-brain barrier, interactions with CYP2D6, hepatotoxicity, and plasma protein binding. The validation results showed that there was no remarkable effect of ginger on the metabolism of warfarin in humans, whereas concurrent use of ginger and nifedipine exhibited a synergistic effect on platelet aggregation in humans. Moreover, ginger components showed a rapid half-life and no to low toxicity in humans. Taken together, this study shows that ginger components may regulate the activity and expression of various human CYPs, probably resulting in alterations in drug clearance and response. More studies are warranted to identify and confirm potential ginger-drug interactions and explore possible interactions of ginger with human CYPs and other functionally important proteins, to reduce and avoid side effects induced by unfavorable ginger-drug interactions.

Estimation of the binding modes with important human cytochrome P450 enzymes, drug interaction potential, pharmacokinetics, and hepatotoxicity of ginger components using molecular docking, computational, and pharmacokinetic modeling studies

PubMed Central

Qiu, Jia-Xuan; Zhou, Zhi-Wei; He, Zhi-Xu; Zhang, Xueji; Zhou, Shu-Feng; Zhu, Shengrong

2015-01-01

Ginger is one of the most commonly used herbal medicines for the treatment of numerous ailments and improvement of body functions. It may be used in combination with prescribed drugs. The coadministration of ginger with therapeutic drugs raises a concern of potential deleterious drug interactions via the modulation of the expression and/or activity of drug-metabolizing enzymes and drug transporters, resulting in unfavorable therapeutic outcomes. This study aimed to determine the molecular interactions between 12 main active ginger components (6-gingerol, 8-gingerol, 10-gingerol, 6-shogaol, 8-shogaol, 10-shogaol, ar-curcumene, β-bisabolene, β-sesquiphelandrene, 6-gingerdione, (−)-zingiberene, and methyl-6-isogingerol) and human cytochrome P450 (CYP) 1A2, 2C9, 2C19, 2D6, and 3A4 and to predict the absorption, distribution, metabolism, excretion, and toxicity (ADMET) of the 12 ginger components using computational approaches and comprehensive literature search. Docking studies showed that ginger components interacted with a panel of amino acids in the active sites of CYP1A2, 2C9, 2C19, 2D6, and 3A4 mainly through hydrogen bond formation, to a lesser extent, via π–π stacking. The pharmacokinetic simulation studies showed that the [I]/[Ki] value for CYP2C9, 2C19, and 3A4 ranged from 0.0002 to 19.6 and the R value ranged from 1.0002 to 20.6 and that ginger might exhibit a high risk of drug interaction via inhibition of the activity of human CYP2C9 and CYP3A4, but a low risk of drug interaction toward CYP2C19-mediated drug metabolism. Furthermore, it has been evaluated that the 12 ginger components possessed a favorable ADMET profiles with regard to the solubility, absorption, permeability across the blood–brain barrier, interactions with CYP2D6, hepatotoxicity, and plasma protein binding. The validation results showed that there was no remarkable effect of ginger on the metabolism of warfarin in humans, whereas concurrent use of ginger and nifedipine exhibited a synergistic effect on platelet aggregation in humans. Moreover, ginger components showed a rapid half-life and no to low toxicity in humans. Taken together, this study shows that ginger components may regulate the activity and expression of various human CYPs, probably resulting in alterations in drug clearance and response. More studies are warranted to identify and confirm potential ginger–drug interactions and explore possible interactions of ginger with human CYPs and other functionally important proteins, to reduce and avoid side effects induced by unfavorable ginger–drug interactions. PMID:25733806

Evaluation of the Effects of S-Allyl-L-cysteine, S-Methyl-L-cysteine, trans-S-1-Propenyl-L-cysteine, and Their N-Acetylated and S-Oxidized Metabolites on Human CYP Activities.

PubMed

Amano, Hirotaka; Kazamori, Daichi; Itoh, Kenji

2016-01-01

Three major organosulfur compounds of aged garlic extract, S-allyl-L-cysteine (SAC), S-methyl-L-cysteine (SMC), and trans-S-1-propenyl-L-cysteine (S1PC), were examined for their effects on the activities of five major isoforms of human CYP enzymes: CYP1A2, 2C9, 2C19, 2D6, and 3A4. The metabolite formation from probe substrates for the CYP isoforms was examined in human liver microsomes in the presence of organosulfur compounds at 0.01-1 mM by using liquid chromatography-tandem mass spectrometry (LC-MS/MS) analysis. Allicin, a major component of garlic, inhibited CYP1A2 and CYP3A4 activity by 21-45% at 0.03 mM. In contrast, a CYP2C9-catalyzed reaction was enhanced by up to 1.9 times in the presence of allicin at 0.003-0.3 mM. SAC, SMC, and S1PC had no effect on the activities of the five isoforms, except that S1PC inhibited CYP3A4-catalyzed midazolam 1'-hydroxylation by 31% at 1 mM. The N-acetylated metabolites of the three compounds inhibited the activities of several isoforms to a varying degree at 1 mM. N-Acetyl-S-allyl-L-cysteine and N-acetyl-S-methyl-L-cysteine inhibited the reactions catalyzed by CYP2D6 and CYP1A2, by 19 and 26%, respectively, whereas trans-N-acetyl-S-1-propenyl-L-cysteine showed weak to moderate inhibition (19-49%) of CYP1A2, 2C19, 2D6, and 3A4 activities. On the other hand, both the N-acetylated and S-oxidized metabolites of SAC, SMC, and S1PC had little effect on the reactions catalyzed by the five isoforms. These results indicated that SAC, SMC, and S1PC have little potential to cause drug-drug interaction due to CYP inhibition or activation in vivo, as judged by their minimal effects (IC 50 >1 mM) on the activities of five major isoforms of human CYP in vitro.

Human extrahepatic cytochromes P450: function in xenobiotic metabolism and tissue-selective chemical toxicity in the respiratory and gastrointestinal tracts.

PubMed

Ding, Xinxin; Kaminsky, Laurence S

2003-01-01

Cytochrome P450 (CYP) enzymes in extrahepatic tissues often play a dominant role in target tissue metabolic activation of xenobiotic compounds. They may also determine drug efficacy and influence the tissue burden of foreign chemicals or bioavailability of therapeutic agents. This review focuses on xenobiotic-metabolizing CYPs of the human respiratory and gastrointestinal tracts, including the lung, trachea, nasal respiratory and olfactory mucosa, esophagus, stomach, small intestine, and colon. Many CYPs are expressed in one or more of these organs, including CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2A13, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1, CYP2F1, CYP2J2, CYP2S1, CYP3A4, CYP3A5, and CYP4B1. Of particular interest are the preferential expression of certain CYPs in the respiratory tract and the regional differences in CYP expression profile in different parts of the gastrointestinal tract. Current research activities on the characterization of CYP expression, function, and regulation in these tissues, as well as future research needs, are discussed.

CYP2C9 polymorphisms and phenytoin metabolism: implications for adverse effects.

PubMed

Franco, Valentina; Perucca, Emilio

2015-01-01

Phenytoin, a widely prescribed old-generation antiepileptic drug, requires careful individualization of dosage to compensate for its prominent pharmacokinetic variability. This article reviews the contribution of genetic polymorphisms affecting the activity of CYP2C9, the main enzyme responsible for phenytoin metabolism, to the variation in phenytoin clearance and susceptibility to adverse effects. Comprehensive and critical review of available evidence concerning the influence of CYP2C9 genetic polymorphism on phenytoin pharmacokinetic and safety profile. There is extensive evidence that CYP2C9 polymorphisms are an important determinant of the rate of phenytoin metabolism, although other factors including expression of other enzymes such as CYP2C19 and the influence of drug interactions, physiological and disease-related factors may also play a role. Patients carrying CYP2C9 genotypes associated with reduced phenytoin clearance are at greater risk of developing CNS adverse effects as well as serious cutaneous adverse reactions when given usual dosages of phenytoin. The clinical value and cost-effectiveness of CYP2C9 genotyping in improving the safety of phenytoin therapy, however, have not been clearly established and require formal testing in well-designed prospective studies.

Phenotype-genotype analysis of CYP2C19 in Colombian mestizo individuals

PubMed Central

Isaza, Carlos; Henao, Julieta; Martínez, José H Isaza; Arias, Juan C Sepúlveda; Beltrán, Leonardo

2007-01-01

Background Omeprazole is metabolized by the hepatic cytochrome P450 (CYP) 2C19 enzyme to 5-hydroxyomeprazole. CYP2C19 exhibits genetic polymorphisms responsible for the presence of poor metabolizers (PMs), intermediate metabolizers (IMs) and extensive metabolizers (EMs). The defective mutations of the enzyme and their frequencies change between different ethnic groups; however, the polymorphism of the CYP2C19 gene has not been studied in Colombian mestizos. The aim of this study was to evaluate the genotype and phenotype status of CYP2C19 in Colombian mestizos, in order to contribute to the use of appropriate strategies of drug therapy for this population. Methods 189 subjects were genotyped using the multiplex SNaPshot technique and a subgroup of 44 individuals received 20 mg of omeprazole followed by blood collection at 3 hours to determine the omeprazole hydroxylation index by HPLC. Results 83.6%, 15.3% and 1.1% of the subjects were genotyped as EMs, IMs and PMs, respectively. The frequencies of the CYP2C29*1 and CYP2C19*2 alleles were 91.3% and 8.7% respectively whereas the *3, *4, *5, *6 and *8 alleles were not found. No discrepancies were found between the genotype and phenotype of CYP2C19. Conclusion The frequency of poor metabolizers (1.1%) in the Colombian mestizos included in this study is similar to that in Bolivian mestizos (1%) but lower than in Mexican-Americans (3.2%), West Mexicans (6%), Caucasians (5%) and African Americans (5.4%). The results of this study will be useful for drug dosage recommendations in Colombian mestizos. PMID:17623107

Differences in the expression of xenobiotic-metabolizing enzymes between islets derived from the ventral and dorsal anlage of the pancreas.

PubMed

Standop, Jens; Ulrich, Alexis B; Schneider, Matthias B; Büchler, Markus W; Pour, Parviz M

2002-01-01

Chronic pancreatitis and pancreatic cancer have been linked to the exposure of environmental chemicals (xenobiotics), which generally require metabolic activation to highly reactive toxic or carcinogenic intermediates. The primary enzyme system involved is made up of numerous cytochrome P450 mono-oxygenases (CYP). Glutathione S-transferases (GST) belong to the enzyme systems that catalyze the conjugation of the reactive intermediates produced by CYPs to less toxic or readily excretable metabolites. Because the majority of chronic pancreatitis and pancreatic cancers develop in the organ's head, we compared the expression of selected CYP and GST enzymes between the tissues deriving from the ventral anlage (head) and dorsal anlage (corpus, tail). A total of 20 normal pancreatic tissue specimen from organ donors and early autopsy cases were processed immunohistochemically by using antibodies to CYP 1A1, 1A2, 2B6, 2C8/9/19, 2D6, 2E1, 3A1, 3A2 and 3A4, GST-alpha, GST-mu and GST-pi, and the NADPH cytochrome P450 oxido-reductase (NA-OR), the specificity of which has been verified in our previous study by Western blot and RT-PCR analyses. In all pancreatic regions, most of the enzymes were expressed in islet cells. However, more islets in the head region expressed CYP 2B6, 2C8/9/19, 2E1 and the NA-OR, than those in the body and tail. Moreover, the expression of CYP 2B6 and 2E1 was restricted to the pancreatic polypeptide (PP) cells, and the concentration of CYP 3A1 and 3A4 was stronger in PP cells than in other islet cells. On the other hand, GST-mu and GST-pi were expressed primarily in islet cells of the body and tail. The greater content of xenobiotic-metabolizing and carcinogen-activating CYP enzymes and a lower expression of detoxifying GST enzymes in the head of the pancreas could be one reason for the greater susceptibility of this region for inflammatory and malignant diseases. Copyright 2002 S. Karger AG, Basel and IAP

Enantiomeric metabolic interactions and stereoselective human methadone metabolism.

PubMed

Totah, Rheem A; Allen, Kyle E; Sheffels, Pamela; Whittington, Dale; Kharasch, Evan D

2007-04-01

Methadone is administered as a racemate, although opioid activity resides in the R-enantiomer. Methadone disposition is stereoselective, with considerable unexplained variability in clearance and plasma R/S ratios. N-Demethylation of methadone in vitro is predominantly mediated by cytochrome P450 CYP3A4 and CYP2B6 and somewhat by CYP2C19. This investigation evaluated stereoselectivity, models, and kinetic parameters for methadone N-demethylation by recombinant CYP2B6, CYP3A4, and CYP2C19, and the potential for interactions between enantiomers during racemate metabolism. CYP2B6 metabolism was stereoselective. CYP2C19 was less active, and stereoselectivity was opposite that for CYP2B6. CYP3A4 was not stereoselective. With all three isoforms, enantiomer N-dealkylation rates in the racemate were lower than those of (R)-(6-dimethyamino-4,4-diphenyl-heptan-3-one) hydrochloride (R-methadone) or (S)-(6-dimethyamino-4,4-diphenyl-heptan-3-one) hydrochloride (S-methadone) alone, suggesting an enantiomeric interaction and mutual metabolic inhibition. For CYP2B6, the interaction between enantiomers was stereoselective, with S-methadone as a more potent inhibitor of R-methadone N-demethylation than R-of S-methadone. In contrast, enantiomer interactions were not stereoselective with CYP2C19 or CYP3A4. For all three cytochromes P450, methadone N-demethylation was best described by two-site enzyme models with competitive inhibition. There were minor model differences between cytochromes P450 to account for stereoselectivity of metabolism and enantiomeric interactions. Changes in plasma R/S methadone ratios observed after rifampin or troleandomycin pretreatment in humans in vivo were successfully predicted by CYP2B6- but not CYP3A4-catalyzed methadone N-demethylation. CYP2B6 is a predominant catalyst of stereoselective methadone metabolism in vitro. In vivo, CYP2B6 may be a major determinant of methadone metabolism and disposition, and CYP2B6 activity and stereoselective metabolic interactions may confer variability in methadone disposition.

Activity levels of tamoxifen metabolites at the estrogen receptor and the impact of genetic polymorphisms of phase I and II enzymes on their concentration levels in plasma.

PubMed

Mürdter, T E; Schroth, W; Bacchus-Gerybadze, L; Winter, S; Heinkele, G; Simon, W; Fasching, P A; Fehm, T; Eichelbaum, M; Schwab, M; Brauch, H

2011-05-01

The therapeutic effect of tamoxifen depends on active metabolites, e.g., cytochrome P450 2D6 (CYP2D6) mediated formation of endoxifen. To test for additional relationships, 236 breast cancer patients were genotyped for CYP2D6, CYP2C9, CYP2B6, CYP2C19, CYP3A5, UGT1A4, UGT2B7, and UGT2B15; also, plasma concentrations of tamoxifen and 22 of its metabolites, including the (E)-, (Z)-, 3-, and 4'-hydroxymetabolites as well as their glucuronides, were quantified using liquid chromatography-tandem mass spectrometry (MS). The activity levels of the metabolites were measured using an estrogen response element reporter assay; the strongest estrogen receptor inhibition was found for (Z)-endoxifen and (Z)-4-hydroxytamoxifen (inhibitory concentration 50 (IC50) 3 and 7 nmol/l, respectively). CYP2D6 genotypes explained 39 and 9% of the variability of steady-state concentrations of (Z)-endoxifen and (Z)-4-hydroxytamoxifen, respectively. Among the poor metabolizers, 93% had (Z)-endoxifen levels below IC90 values, underscoring the role of CYP2D6 deficiency in compromised tamoxifen bioactivation. For other enzymes tested, carriers of reduced-function CYP2C9 (*2, *3) alleles had lower plasma concentrations of active metabolites (P < 0.004), pointing to the role of additional pathways.

CYP3A4 Mediates Oxidative Metabolism of the Synthetic Cannabinoid AKB-48.

PubMed

Holm, Niels Bjerre; Nielsen, Line Marie; Linnet, Kristian

2015-09-01

Synthetic cannabinoid designer drugs have emerged as drugs of abuse during the last decade, and acute intoxication cases are documented in the scientific literature. Synthetic cannabinoids are extensively metabolized, but our knowledge of the involved enzymes is limited. Here, we investigated the metabolism of N-(1-adamantyl)-1-pentyl-1H-indazole-3-carboxamide (AKB-48), a compound identified in herbal blends from 2012 and onwards. We screened for metabolite formation using a panel of nine recombinant cytochrome P450 (CYP) enzymes (CYP1A2, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, and 3A4) and compared the formed metabolites to human liver microsomal (HLM) incubations with specific inhibitors against CYP2D6, 2C19, and 3A4, respectively. The data reported here demonstrate CYP3A4 to be the major CYP enzyme responsible for the oxidative metabolism of AKB-48, preferentially performing the oxidation on the adamantyl moiety. Genetic polymorphisms are likely not important with regard to toxicity given the major involvement of CYP3A4. Adverse drug-drug interactions (DDIs) could potentially occur in cases with co-intake of strong CYP3A4 inhibitors, e.g., HIV antivirals and azole antifungal agents.

Evaluation of a microarray-based genotyping assay for the rapid detection of cytochrome P450 2C19 *2 and *3 polymorphisms from whole blood using nanoparticle probes.

PubMed

Buchan, Blake W; Peterson, Jess F; Cogbill, Christopher H; Anderson, Dennis K; Ledford, Joellen S; White, Mary N; Quigley, Neil B; Jannetto, Paul J; Ledeboer, Nathan A

2011-10-01

Numerous drugs such as clopidogrel have been developed to reduce coagulation or inhibit platelet function. The hepatic cytochrome P450 (CYP) pathway is involved in the conversion of clopidogrel to its active metabolite. A recent black-box warning was included in the clopidogrel package insert indicating a significant clinical link between specific CYP2C19 genetic variants and poor metabolism of clopidogrel. Of these variants, *2 and *3 are the most common and are associated with complete loss of enzyme activity. In patients who are carriers of a CYP2C19 *2 or *3 allele, the conversion of clopidogrel to its active metabolite may be reduced, which can lead to ischemic events and negative consequence for the patient. We examined the ability of the Verigene CLO assay (Nanosphere, Northbrook, IL) to identify CYP2C19 *2 and *3 polymorphisms in 1,286 unique whole blood samples. The Verigene CLO assay accurately identified homozygous and heterozygous *2 and *3 phenotypes with a specificity of 100% and a final call rate of 99.7%. The assay is fully automated and can produce a result in approximately 3.5 hours.

Studies on Pharmacokinetic Drug Interaction Potential of Vinpocetine

PubMed Central

Manda, Vamshi K.; Avula, Bharathi; Dale, Olivia R.; Chittiboyina, Amar G.; Khan, Ikhlas A.; Walker, Larry A.; Khan, Shabana I.

2015-01-01

Abstract Background Vinpocetine, a semi-synthetic derivative of vincamine, is a popular dietary supplement used for the treatment of several central nervous system related disorders. Despite its wide use, no pharmacokinetic drug interaction studies are reported in the literature. Due to increasing use of dietary supplements in combination with conventional drugs, the risk of adverse effects is on the rise. As a preliminary step to predict a possibility of drug interaction during concomitant use of vinpocetine and conventional drugs, this study was carried out to evaluate the effects of vinpocetine on three main regulators of pharmacokinetic drug interactions namely, cytochromes P450 (CYPs), P-glycoprotein (P-gp), and Pregnane X receptor (PXR). Methods Inhibition of CYPs was evaluated by employing recombinant enzymes. The inhibition of P-gp was determined by calcein-AM uptake method in transfected and wild type MDCKII cells. Modulation of PXR activity was monitored through a reporter gene assay in HepG2 cells. Results Vinpocetine showed a strong inhibition of P-gp (EC50 8 μM) and a moderate inhibition of recombinant CYP3A4 and CYP2D6 (IC50 2.8 and 6.5 μM) with no activity towards CYP2C9, CYP2C19 and CYP1A2 enzymes. In HLM, competitive inhibition of CYP3A4 (IC50 54 and Ki 19 μM) and non-competitive inhibition of CYP2D6 (IC50 19 and Ki 26 μM) was observed. Activation of PXR was observed only at the highest tested concentration of vinpocetine (30 μM) while lower doses were ineffective. Conclusion Strong inhibition of P-gp by vinpocetine is indicative of a possibility of drug interactions by altering the pharmacokinetics of drugs, which are the substrates of P-gp. However, the effects on CYPs and PXR indicate that vinpocetine may not affect CYP-mediated metabolism of drugs, as the inhibitory concentrations are much greater than the expected plasma concentrations in humans. PMID:28930203

Studies on Pharmacokinetic Drug Interaction Potential of Vinpocetine.

PubMed

Manda, Vamshi K; Avula, Bharathi; Dale, Olivia R; Chittiboyina, Amar G; Khan, Ikhlas A; Walker, Larry A; Khan, Shabana I

2015-06-05

Background: Vinpocetine, a semi-synthetic derivative of vincamine, is a popular dietary supplement used for the treatment of several central nervous system related disorders. Despite its wide use, no pharmacokinetic drug interaction studies are reported in the literature. Due to increasing use of dietary supplements in combination with conventional drugs, the risk of adverse effects is on the rise. As a preliminary step to predict a possibility of drug interaction during concomitant use of vinpocetine and conventional drugs, this study was carried out to evaluate the effects of vinpocetine on three main regulators of pharmacokinetic drug interactions namely, cytochromes P450 (CYPs), P-glycoprotein (P-gp), and Pregnane X receptor (PXR). Methods: Inhibition of CYPs was evaluated by employing recombinant enzymes. The inhibition of P-gp was determined by calcein-AM uptake method in transfected and wild type MDCKII cells. Modulation of PXR activity was monitored through a reporter gene assay in HepG2 cells. Results: Vinpocetine showed a strong inhibition of P-gp (EC 50 8 µM) and a moderate inhibition of recombinant CYP3A4 and CYP2D6 (IC 50 2.8 and 6.5 µM) with no activity towards CYP2C9, CYP2C19 and CYP1A2 enzymes. In HLM, competitive inhibition of CYP3A4 (IC 50 54 and K i 19 µM) and non-competitive inhibition of CYP2D6 (IC 50 19 and K i 26 µM) was observed. Activation of PXR was observed only at the highest tested concentration of vinpocetine (30 µM) while lower doses were ineffective. Conclusion: Strong inhibition of P-gp by vinpocetine is indicative of a possibility of drug interactions by altering the pharmacokinetics of drugs, which are the substrates of P-gp. However, the effects on CYPs and PXR indicate that vinpocetine may not affect CYP-mediated metabolism of drugs, as the inhibitory concentrations are much greater than the expected plasma concentrations in humans.

Investigation of the in vivo activity of CYP3A in Brazilian volunteers: comparison of midazolam and omeprazole as drug markers.

PubMed

Rocha, Adriana; Coelho, Eduardo B; Moussa, Soraia A P; Lanchote, Vera L

2008-09-01

This study compares midazolam with omeprazole as marker drugs for the evaluation of CYP3A activity in nine healthy self-reported white Brazilian volunteers. Omeprazole was also used to evaluate the CYP2C19 phenotype. The volunteers received p.o. 20 mg omeprazole, and blood samples were collected 3.5 h after drug administration. After a washout period of 10 days, the volunteers received p.o. 15 mg midazolam maleate, and serial blood samples were collected up to 6 h after administration of the drug. CYP2C19 was genotyped for the allelic variants CYP2C19*1, CYP2C19*2, CYP2C19*3, and CYP2C19*17. Analysis of omeprazole, hydroxyomeprazole, omeprazole sulfone, and midazolam in plasma was carried out by LC-MS/MS. The volunteers genotyped as CYP2C19*1*17, CYP2C19*17*17, CYP2C19*1*1 (n = 8), or CYP2C19*17*2 (n = 1) presented a median hydroxylation index (omeprazole/hydroxyomeprazole) of 1.35, indicating that all of them were extensive metabolizers of CYP2C19. The volunteers (n = 9) presented a 0.12 log of the omeprazole/sulfone ratio and a median oral clearance of midazolam of 17.89 ml min(-1) kg(-1), suggesting normal CYP3A activity. Orthogonal regression analysis between midazolam clearance and log of the plasma concentrations of the omeprazole/omeprazole sulfone ratio (R = -0.7544, P < 0.05) suggests that both midazolam and omeprazole can be used as markers of CYP3A activity in the population investigated.

A High-Throughput (HTS) Assay for Enzyme Reaction Phenotyping in Human Recombinant P450 Enzymes Using LC-MS/MS.

PubMed

Li, Xiaofeng; Suhar, Tom; Glass, Lateca; Rajaraman, Ganesh

2014-03-03

Enzyme reaction phenotyping is employed extensively during the early stages of drug discovery to identify the enzymes responsible for the metabolism of new chemical entities (NCEs). Early identification of metabolic pathways facilitates prediction of potential drug-drug interactions associated with enzyme polymorphism, induction, or inhibition, and aids in the design of clinical trials. Incubation of NCEs with human recombinant enzymes is a popular method for such work because of the specificity, simplicity, and high-throughput nature of this approach for phenotyping studies. The availability of a relative abundance factor and calculated intersystem extrapolation factor for the expressed recombinant enzymes facilitates easy scaling of in vitro data, enabling in vitro-in vivo extrapolation. Described in this unit is a high-throughput screen for identifying enzymes involved in the metabolism of NCEs. Emphasis is placed on the analysis of the human recombinant enzymes CYP1A2, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2B6, and CYP3A4, including the calculation of the intrinsic clearance for each. Copyright © 2014 John Wiley & Sons, Inc. All rights reserved.

CYP2C19 progress curve analysis and mechanism-based inactivation by three methylenedioxyphenyl compounds.

PubMed

Salminen, Kaisa A; Meyer, Achim; Imming, Peter; Raunio, Hannu

2011-12-01

Several in vitro criteria were used to assess whether three methylenedioxyphenyl (MDP) compounds, the isoquinoline alkaloids bulbocapnine, canadine, and protopine, are mechanism-based inactivators of CYP2C19. The recently reported fluorometric CYP2C19 progress curve analysis approach was applied first to determine whether these alkaloids demonstrate time-dependent inhibition. In this experiment, bulbocapnine, canadine, and protopine displayed time dependence and saturation in their inactivation kinetics with K(I) and k(inact) values of 72.4 ± 14.7 μM and 0.38 ± 0.036 min(-1), 2.1 ± 0.63 μM and 0.18 ± 0.015 min(-1), and 7.1 ± 2.3 μM and 0.24 ± 0.021 min(-1), respectively. Additional studies were performed to determine whether other specific criteria for mechanism-based inactivation were fulfilled: NADPH dependence, irreversibility, and involvement of a catalytic step in the enzyme inactivation. CYP2C19 activity was not significantly restored by dialysis when it had been inactivated by the alkaloids in the presence of a NADPH-regenerating system, and a metabolic-intermediate complex-associated increase in absorbance at approximately 455 nm was observed. In conclusion, the CYP2C19 progress curve analysis method revealed time-dependent inhibition by these alkaloids, and additional experiments confirmed its quasi-irreversible nature. This study revealed that the CYP2C19 progress curve analysis method is useful for identifying novel mechanism-based inactivators and yields a wealth of information in one run. The alkaloids bulbocapnine, canadine, and protopine, present in herbal medicines, are new mechanism-based inactivators and the first MDP compounds exhibiting quasi-irreversible inactivation of CYP2C19.

Poor Metabolizers at the Cytochrome P450 2C19 Loci Is at Increased Risk of Developing Cancer in Asian Populations

PubMed Central

Chen, Zenggan; Yu, Yanmin

2013-01-01

Background CYP2C19 encodes a member of the cytochrome P450 superfamily of enzymes, which play a central role in activating and detoxifying many carcinogens and endogenous compounds thought to be involved in the development of cancer. In the past decade, two common polymorphisms among CYP2C19 (CYP2C19*2 and CYP2C19*3) that are responsible for the poor metabolizers (PMs) phenotype in humans and cancer susceptibility have been investigated extensively; however, these studies have yielded contradictory results. Methods and Results To investigate this inconsistency, we conducted a comprehensive meta-analysis of 11,554 cases and 16,592 controls from 30 case-control studies. Overall, the odds ratio (OR) of cancer was 1.52 [95% confidence interval (CI): 1.23–1.88, P<10-4] for CYP2C19 PMs genotypes. However, this significant association vanished when the analyses were restricted to 5 larger studies (no. of cases ≥ 500 cases). In the subgroup analysis for different cancer types, PMs genotypes had an effect of increasing the risks of esophagus cancer, gastric cancer, lung cancer and hepatocellular carcinoma as well as head neck cancer. Significant results were found in Asian populations when stratified by ethnicity; whereas no significant associations were found among Caucasians. Stratified analyses according to source of controls, significant associations were found only in hospital base controls. Conclusions Our meta-analysis suggests that the CYP2C19 PMs genotypes most likely contributes to cancer susceptibility, particularly in the Asian populations. PMID:24015291

Frequencies of 23 Functionally Significant Variant Alleles Related with Metabolism of Antineoplastic Drugs in the Chilean Population: Comparison with Caucasian and Asian Populations

PubMed Central

Roco, Ángela; Quiñones, Luis; Agúndez, José A. G.; García-Martín, Elena; Squicciarini, Valentina; Miranda, Carla; Garay, Joselyn; Farfán, Nancy; Saavedra, Iván; Cáceres, Dante; Ibarra, Carol; Varela, Nelson

2012-01-01

Cancer is a leading cause of death worldwide. The cancer incidence rate in Chile is 133.7/100,000 inhabitants and it is the second cause of death, after cardiovascular diseases. Most of the antineoplastic drugs are metabolized to be detoxified, and some of them to be activated. Genetic polymorphisms of drug-metabolizing enzymes can induce deep changes in enzyme activity, leading to individual variability in drug efficacy and/or toxicity. The present research describes the presence of genetic polymorphisms in the Chilean population, which might be useful in public health programs for personalized treatment of cancer, and compares these frequencies with those reported for Asian and Caucasian populations, as a contribution to the evaluation of ethnic differences in the response to chemotherapy. We analyzed 23 polymorphisms in a group of 253 unrelated Chilean volunteers from the general population. The results showed that CYP2A6*2, CYP2A6*3, CYP2D6*3, CYP2C19*3, and CYP3A4*17 variant alleles are virtually absent in Chileans. CYP1A1*2A allele frequency (0.37) is similar to that of Caucasians and higher than that reported for Japanese people. Allele frequencies for CYP3A5*3(0.76) and CYP2C9*3(0.04) are similar to those observed in Japanese people. CYP1A1*2C(0.32), CYP1A2*1F(0.77), CYP3A4*1B(0.06), CYP2D6*2(0.41), and MTHFR T(0.52) allele frequencies are higher than the observed either in Caucasian or in Japanese populations. Conversely, CYP2C19*2 allelic frequency (0.12), and genotype frequencies for GSTT1 null (0.11) and GSTM1 null (0.36) are lower than those observed in both populations. Finally, allele frequencies for CYP2A6*4(0.04), CYP2C8*3(0.06), CYP2C9*2(0.06), CYP2D6*4(0.12), CYP2E1*5B(0.14), CYP2E1*6(0.19), and UGT2B7*2(0.40) are intermediate in relation to those described in Caucasian and in Japanese populations, as expected according to the ethnic origin of the Chilean population. In conclusion, our findings support the idea that ethnic variability must be considered in the pharmacogenomic assessment of cancer pharmacotherapy, especially in mixed populations and for drugs with a narrow safety range. PMID:23130019

[Effect of oligosaccharide esters and polygalaxanthone Ill from Polygala tenuifolia willd towards cytochrome P450].

PubMed

Li, Zhao-liang; Dong, Xian-zhe; Wang, Dong-xiao; Dong, Rui-hua; Guo, Ting-ting; Sun, Yan; Liu, Ping

2014-11-01

Five compounds (tenuifoliside C, tenuifoliside D, telephiose A, telephiose C and polygalaxanthone III) from polygala tenuifolia wild were incubated together with CYP probe substrate in human liver microsomes to investigate the inhibitory effect towards CYP450 enzyme. Phenacetin (CYP1A2), coumarin (CYP2A6), paclitaxel (CYP2C8), diclofenac (CYP2C9), S-mepheriytoin (CYP2C19), dextromethorphan (CYP2D6), chlorzoxazone (CYP2E1), midazolam (CYP3A) were selected as the isoforfn specific substrate. And the formation of paracetamol, 7-hydroxycoumarin, 6alpha-hydroxy paclitaxel, 4'-hydroxydiclofenac, dextrorphan, 6-hydroxychlorzoxazone, 1'-hydroxymidazolam, 4'-hydroxymephenytoin were detected respectively to measure the effect towards CYP450 by high-pressure liquid chromatography (HPLC). The result shows that five compounds from polygala tenuifolia willd significantly inhibit chlorzoxazone 6-hydroxylation catalyzed by CYP2E1, while showed no effect towards CYP1A2, CYP2A6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP3A. And IC50 value was 38.73, 54.14, 61.77, 62.22, 50.56 micromol x L(-1), respectively.

Characterization of human liver cytochrome P-450 enzymes involved in the O-demethylation of a new P-glycoprotein inhibitor HM-30181.

PubMed

Paek, In Bok; Kim, Sung Yeon; Kim, Maeng Sup; Kim, John; Lee, Gwansun; Lee, Hye Suk

2007-08-01

HM-30181, 4-oxo-4H-chromene-2-carboxylic acid [2-(2-{4-[2-(6,7-dimethoxy-3,4-dihydro-1H-isoquinolin-2-yl)-ethyl]-phenyl}-2H-tetrazol-5-yl)-4,5-dimethoxy-phenyl]-amide, is a new P-glycoprotein inhibitor with the potential to increase the cytotoxic activity of orally coadministered paclitaxel. This study was performed to characterize human cytochrome P-450 (CYP) enzymes involved in the metabolism of HM-30181 to 4- or 5-O-desmethyl-HM-30181 (M2) and 6- or 7-O-desmethyl-HM-30181 (M3) and to investigate the inhibitory potential of HM-30181 on CYP enzymes in human liver microsomes. CYP3A4 was identified as the major isozyme responsible for the O-demethylation of HM-30181 to M2 and M3 based on the correlation analysis, chemical inhibition and immuno-inhibition study and metabolism in cDNA-expressed human CYP isozymes. HM-30181 itself had no inhibitory effects on CYPs 1A2, 2A6, 2C8, 2C9, 2C19, 2D6, and 3A4 in human liver microsomes, suggesting the possibility that the pharmacokinetics of HM-30181 could be changed with coadministration of known CYP3A4 inducers or inhibitors.

Cytochrome P450 isoforms in the Metabolism of Decursin and Decursinol Angelate from Korean Angelica

PubMed Central

ZHANG, Jinhui; LI, Li; TANG, Suni; HALE, Thomas W.; XING, Chengguo; JIANG, Cheng; LÜ, Junxuan

2016-01-01

We have shown that the in vitro hepatic microsomal metabolism of pyranocoumarin compound decursinol angelate (DA) to decursinol (DOH) exclusively requires cytochrome P450 enzymes (CYP) whereas the conversion of its isomer decursin (D) to DOH can be mediated by CYP and esterase(s). To provide insight into specific isoforms involved, here we show with recombinant human CYP that 2C19 was the most active at metabolizing D and DA in vitro followed by 3A4. With carboxylesterases (CES), D was hydrolyzed by CES2 but not CES1, and DA was resistant to both CES1 and CES2. In human liver microsomal preparation, general CYP inhibitor 1-aminobenzotriazole (ABT) and respective competitive inhibitors for 2C19 and 3A4, (+)-N-3-benzylnirvanol and ketoconazole, substantially retarded the metabolism of DA and, to a lesser extent, of D. In healthy human subjects from a single-dose pharmacokinetic study, 2C19 extensive metabolizer genotype (2C19*17 allele) tended to have less plasma DA AUC0–48h and poor metabolizer genotype (2C19*2 allele) tended to have greater DA AUC0–48h. In mice given a single dose of D/DA, pretreatment with ABT boosted the plasma and prostate levels of D and DA by more than an order of magnitude. Taken together, our findings suggest that CYP isoforms 2C19 and 3A4 may play a crucial role in the first pass liver metabolism of DA and, to a lesser extent, that of D in humans. Pharmacogenetics with respect to CYP genotypes and interactions among CYP inhibitor drugs and D/DA should therefore be considered in designing future translation studies of DA and/or D. PMID:26394652

Cytochrome P450 Isoforms in the Metabolism of Decursin and Decursinol Angelate from Korean Angelica.

PubMed

Zhang, Jinhui; Li, Li; Tang, Suni; Hale, Thomas W; Xing, Chengguo; Jiang, Cheng; Lü, Junxuan

2015-01-01

We have shown that the in vitro hepatic microsomal metabolism of pyranocoumarin compound decursinol angelate (DA) to decursinol (DOH) exclusively requires cytochrome P450 (CYP) enzymes, whereas the conversion of its isomer decursin (D) to DOH can be mediated by CYP and esterase(s). To provide insight into specific isoforms involved, here we show with recombinant human CYP that 2C19 was the most active at metabolizing D and DA in vitro followed by 3A4. With carboxylesterases (CES), D was hydrolyzed by CES2 but not CES1, and DA was resistant to both CES1 and CES2. In human liver microsomal (HLM) preparation, the general CYP inhibitor 1-aminobenzotriazole (ABT) and respective competitive inhibitors for 2C19 and 3A4, (+)-N-3-benzylnirvanol (NBN) and ketoconazole substantially retarded the metabolism of DA and, to a lesser extent, of D. In healthy human subjects from a single-dose pharmacokinetic (PK) study, 2C19 extensive metabolizer genotype (2C19*17 allele) tended to have less plasma DA AUC0-48h and poor metabolizer genotype (2C19*2 allele) tended to have greater DA AUC0-48h. In mice given a single dose of D/DA, pretreatment with ABT boosted the plasma and prostate levels of D and DA by more than an order of magnitude. Taken together, our findings suggest that CYP isoforms 2C19 and 3A4 may play a crucial role in the first pass liver metabolism of DA and, to a lesser extent, that of D in humans. Pharmacogenetics with respect to CYP genotypes and interactions among CYP inhibitor drugs and D/DA should therefore be considered in designing future translation studies of DA and/or D.

Comparative study of the oxidation of propranolol enantiomers in hepatic and small intestinal microsomes from cynomolgus and marmoset monkeys.

PubMed

Shimizudani, Takeshi; Nagaoka, Kenjiro; Hanioka, Nobumitsu; Yamano, Shigeru; Narimatsu, Shizuo

2010-01-05

Oxidative metabolism of propranolol (PL) enantiomers (R-PL and S-PL) to 4-hydroxypropranolol (4-OH-PL), 5-OH-PL and N-deisopropylpropranolol (NDP) was examined in hepatic microsomes from cynomolgus and marmoset monkeys and in small intestinal microsomes from monkeys and humans. In hepatic microsomes, levels of oxidation activities were similar between the two monkey species, and substrate enantioselectivity (R-PLS-PL) was seen in the formation of NDP in cynomolgus monkeys and humans and in the formation of 5-OH-PL in marmosets. The formation of the three metabolites in cynomolgus monkeys and the formation of NDP in marmosets were biphasic, while the formation of 4-OH-PL in humans was monophasic. From the inhibition experiments using CYP antibodies, CYP2C9 and 2C19 were thought to be involved as N-deisopropylases and CYP2D6 and 3A4 as 4-hydroxylases in human small intestine. Furthermore, CYP1A, 2C and 3A enzymes could be involved in cynomolgus monkeys and CYP2C and 3A enzymes in marmosets. These results indicate that the oxidative profile of PL in hepatic and small intestinal microsomes differ considerably among cynomolgus monkeys, marmosets and humans.

CYP63A2, a catalytically versatile fungal P450 monooxygenase capable of oxidizing higher-molecular-weight polycyclic aromatic hydrocarbons, alkylphenols, and alkanes.

PubMed

Syed, Khajamohiddin; Porollo, Aleksey; Lam, Ying Wai; Grimmett, Paul E; Yadav, Jagjit S

2013-04-01

Cytochrome P450 monooxygenases (P450s) are known to oxidize hydrocarbons, albeit with limited substrate specificity across classes of these compounds. Here we report a P450 monooxygenase (CYP63A2) from the model ligninolytic white rot fungus Phanerochaete chrysosporium that was found to possess a broad oxidizing capability toward structurally diverse hydrocarbons belonging to mutagenic/carcinogenic fused-ring higher-molecular-weight polycyclic aromatic hydrocarbons (HMW-PAHs), endocrine-disrupting long-chain alkylphenols (APs), and crude oil aliphatic hydrocarbon n-alkanes. A homology-based three-dimensional (3D) model revealed the presence of an extraordinarily large active-site cavity in CYP63A2 compared to the mammalian PAH-oxidizing (CYP3A4, CYP1A2, and CYP1B1) and bacterial aliphatic-hydrocarbon-oxidizing (CYP101D and CYP102A1) P450s. This structural feature in conjunction with ligand docking simulations suggested potential versatility of the enzyme. Experimental characterization using recombinantly expressed CYP63A2 revealed its ability to oxidize HMW-PAHs of various ring sizes, including 4 rings (pyrene and fluoranthene), 5 rings [benzo(a)pyrene], and 6 rings [benzo(ghi)perylene], with the highest enzymatic activity being toward the 5-ring PAH followed by the 4-ring and 6-ring PAHs, in that order. Recombinant CYP63A2 activity yielded monohydroxylated PAH metabolites. The enzyme was found to also act as an alkane ω-hydroxylase that oxidized n-alkanes with various chain lengths (C9 to C12 and C15 to C19), as well as alkyl side chains (C3 to C9) in alkylphenols (APs). CYP63A2 showed preferential oxidation of long-chain APs and alkanes. To our knowledge, this is the first P450 identified from any of the biological kingdoms that possesses such broad substrate specificity toward structurally diverse xenobiotics (PAHs, APs, and alkanes), making it a potent enzyme biocatalyst candidate to handle mixed pollution (e.g., crude oil spills).

CYP63A2, a Catalytically Versatile Fungal P450 Monooxygenase Capable of Oxidizing Higher-Molecular-Weight Polycyclic Aromatic Hydrocarbons, Alkylphenols, and Alkanes

PubMed Central

Syed, Khajamohiddin; Porollo, Aleksey; Lam, Ying Wai; Grimmett, Paul E.

2013-01-01

Cytochrome P450 monooxygenases (P450s) are known to oxidize hydrocarbons, albeit with limited substrate specificity across classes of these compounds. Here we report a P450 monooxygenase (CYP63A2) from the model ligninolytic white rot fungus Phanerochaete chrysosporium that was found to possess a broad oxidizing capability toward structurally diverse hydrocarbons belonging to mutagenic/carcinogenic fused-ring higher-molecular-weight polycyclic aromatic hydrocarbons (HMW-PAHs), endocrine-disrupting long-chain alkylphenols (APs), and crude oil aliphatic hydrocarbon n-alkanes. A homology-based three-dimensional (3D) model revealed the presence of an extraordinarily large active-site cavity in CYP63A2 compared to the mammalian PAH-oxidizing (CYP3A4, CYP1A2, and CYP1B1) and bacterial aliphatic-hydrocarbon-oxidizing (CYP101D and CYP102A1) P450s. This structural feature in conjunction with ligand docking simulations suggested potential versatility of the enzyme. Experimental characterization using recombinantly expressed CYP63A2 revealed its ability to oxidize HMW-PAHs of various ring sizes, including 4 rings (pyrene and fluoranthene), 5 rings [benzo(a)pyrene], and 6 rings [benzo(ghi)perylene], with the highest enzymatic activity being toward the 5-ring PAH followed by the 4-ring and 6-ring PAHs, in that order. Recombinant CYP63A2 activity yielded monohydroxylated PAH metabolites. The enzyme was found to also act as an alkane ω-hydroxylase that oxidized n-alkanes with various chain lengths (C9 to C12 and C15 to C19), as well as alkyl side chains (C3 to C9) in alkylphenols (APs). CYP63A2 showed preferential oxidation of long-chain APs and alkanes. To our knowledge, this is the first P450 identified from any of the biological kingdoms that possesses such broad substrate specificity toward structurally diverse xenobiotics (PAHs, APs, and alkanes), making it a potent enzyme biocatalyst candidate to handle mixed pollution (e.g., crude oil spills). PMID:23416995

Fasting-Induced Changes in Hepatic P450 Mediated Drug Metabolism Are Largely Independent of the Constitutive Androstane Receptor CAR.

PubMed

de Vries, E M; Lammers, L A; Achterbergh, R; Klümpen, H-J; Mathot, R A A; Boelen, A; Romijn, J A

2016-01-01

Hepatic drug metabolism by cytochrome P450 enzymes is altered by the nutritional status of patients. The expression of P450 enzymes is partly regulated by the constitutive androstane receptor (CAR). Fasting regulates the expression of both P450 enzymes and CAR and affects hepatic drug clearance. We hypothesized that the fasting-induced alterations in P450 mediated drug clearance are mediated by CAR. To investigate this we used a drug cocktail validated in humans consisting of five widely prescribed drugs as probes for specific P450 enzymes: caffeine (CYP1A2), metoprolol (CYP2D6), omeprazole (CYP2C19), midazolam (CYP3A4) and s-warfarin (CYP2C9). This cocktail was administered to wild type (WT, C57Bl/6) mice or mice deficient for CAR (CAR-/-) that were either fed ad libitum or fasted for 24 hours. Blood was sampled at predefined intervals and drug concentrations were measured as well as hepatic mRNA expression of homologous/orthologous P450 enzymes (Cyp1a2, Cyp2d22, Cyp3a11, Cyp2c37, Cyp2c38 and Cyp2c65). Fasting decreased Cyp1a2 and Cyp2d22 expression and increased Cyp3a11 and Cyp2c38 expression in both WT and CAR-/- mice. The decrease in Cyp1a2 was diminished in CAR-/- in comparison with WT mice. Basal Cyp2c37 expression was lower in CAR-/- compared to WT mice. Fasting decreased the clearance of all drugs tested in both WT and CAR-/- mice. The absence of CAR was associated with an decrease in the clearance of omeprazole, metoprolol and midazolam in fed mice. The fasting-induced reduction in clearance of s-warfarin was greater in WT than in CAR-/-. The changes in drug clearance correlated with the expression pattern of the specific P450 enzymes in case of Cyp1a2-caffeine and Cyp2c37-omeprazole. We conclude that CAR is important for hepatic clearance of several widely prescribed drugs metabolized by P450 enzymes. However the fasting-induced alterations in P450 mediated drug clearance are largely independent of CAR.

Human variation and CYP enzyme contribution in benfuracarb metabolism in human in vitro hepatic models.

PubMed

Abass, Khaled; Reponen, Petri; Mattila, Sampo; Rautio, Arja; Pelkonen, Olavi

2014-01-13

Human responses to the toxicological effects of chemicals are often complicated by a substantial interindividual variability in toxicokinetics, of which metabolism is often the most important factor. Therefore, we investigated human variation and the contributions of human-CYP isoforms to in vitro metabolism of benfuracarb. The primary metabolic pathways were the initial sulfur oxidation to benfuracarb-sulfoxide and the nitrogen-sulfur bond cleavage to carbofuran (activation). The Km, Vmax, and CL(int) values of carbofuran production in ten individual hepatic samples varied 7.3-, 3.4-, and 5.4-fold, respectively. CYP2C9 and CYP2C19 catalyzed benfuracarb sulphur oxidation. Carbofuran formation, representing from 79% to 98% of the total metabolism, was catalyzed predominantly by CYP3A4. The calculated relative contribution of CYP3A4 to carbofuran formation was 93%, while it was 4.4% for CYP2C9. The major contribution of CYP3A4 in benfuracarb metabolism was further substantiated by showing a strong correlation with CYP3A4-selective markers midazolam-1'-hydroxylation and omeprazole-sulfoxidation (r=0.885 and 0.772, respectively). Carbofuran formation was highly inhibited by the CYP3A inhibitor ketoconazole. Moreover, CYP3A4 marker activities were relatively inhibited by benfuracarb. These results confirm that human CYP3A4 is the major enzyme involved in the in vitro activation of benfuracarb and that CYP3A4-catalyzed metabolism is the primary source of interindividual differences. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Enzymes and Inhibitors in Neonicotinoid Insecticide Metabolism

PubMed Central

Shi, Xueyan; Dick, Ryan A.; Ford, Kevin A.; Casida, John E.

2009-01-01

Neonicotinoid insecticide metabolism involves considerable substrate specificity and regioselectivity of the relevant CYP450, aldehyde oxidase, and phase II enzymes. Human CYP450 recombinant enzymes carry out the following conversions: CYP3A4, 2C19 and 2B6 for thiamethoxam (TMX) to clothianidin (CLO); 3A4, 2C19 and 2A6 for CLO to desmethyl-CLO; 2C19 for TMX to desmethyl-TMX. Human liver aldehyde oxidase reduces the nitro substituent of CLO to nitroso much more rapidly than that of TMX. Imidacloprid (IMI), CLO and several of their metabolites do not give detectable N-glucuronides but 5-hydroxy-IMI, 4,5-diol-IMI and 4-hydroxy-thiacloprid are converted to O-glucuronides in vitro with mouse liver microsomes and UDP-glucuronic acid or in vivo in mice. Mouse liver cytosol with S-adenosylmethionine converts desmethyl-CLO to CLO but not desmethyl-TMX to TMX. Two organophosphorus CYP450 inhibitors partially block IMI, thiacloprid and CLO metabolism in vivo in mice, elevating the brain and liver levels of the parent compounds while reducing amounts of the hydroxylated metabolites. PMID:19391582

Drug metabolising enzyme polymorphisms in Middle- and Eastern-European Slavic populations.

PubMed

Hubacek, Jaroslav A

2014-01-01

Inter-individual differences in genes for drug metabolising enzymes and drug transporters are important for understanding efficacy in drug therapy. These differences are important both for the timely estimation of the dosage that should be prescribed to a patient and for the detection of individuals who are prone to side effects from the drug at normal doses. This review summarises the literature concerning the gene variants within nine major drug metabolising enzymes and drug transporters (i.e., CYP1A2, CYP2A6, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4, CYP3A5, and MDR-1) in the Middle European region. Notably, published data are not extensive, and most studies were performed on relatively low numbers of individuals. No country has a complete coverage of all genes. Two variants (C2677T/A and C3435T) within the multidrug resistance-1 (MDR-1) gene and variants within the CYP2C9 gene were analysed within most Slavic populations. Nevertheless, even from this incomplete coverage (where unexpectedly high variability was at times seen both between and within populations), it could be extrapolated that the variants within the drug metabolising enzyme genes are present in roughly the same frequencies as in neighbouring countries.

Evaluation of the activity of CYP2C19 in Gujrati and Marwadi subjects living in Mumbai (Bombay).

PubMed

Panchabhai, Tanmay S; Noronha, Shaun F; Davis, Sanish; Shinde, Vishal M; Kshirsagar, Nilima A; Gogtay, Nithya J

2006-10-24

Inherited differences in the metabolism and disposition of drugs, and genetic polymorphisms in the targets of drug therapy (e.g., receptors), can greatly influence efficacy and toxicity of medications. Marked interethnic differences in CYP2C19 (a member of the cytochrome P-450 enzyme superfamily catalyzing phase I drug metabolism) which affects the metabolism of a number of clinically important drugs have been documented. The present study evaluated the activity of CYP2C19 in normal, healthy Gujrati and Marwadi subjects by phenotyping (a western Indian population). All subjects received 20 mg of omeprazole, which was followed by blood collection at 3 hrs to estimate the metabolic ratio of omeprazole to 5-hydroxyomeprazole. The analysis was done by HPLC. It was seen that 10.36% of this population were poor metabolizers(PM) whereas 89.63% were extensive metabolizers(EM). A genotyping evaluation would better help in identifying population specific genotypes and thus help individualize drug therapy.

Novel drug metabolism indices for pharmacogenetic functional status based on combinatory genotyping of CYP2C9, CYP2C19 and CYP2D6 genes

PubMed Central

Villagra, David; Goethe, John; Schwartz, Harold I; Szarek, Bonnie; Kocherla, Mohan; Gorowski, Krystyna; Windemuth, Andreas; Ruaño, Gualberto

2011-01-01

Aims We aim to demonstrate clinical relevance and utility of four novel drug-metabolism indices derived from a combinatory (multigene) approach to CYP2C9, CYP2C19 and CYP2D6 allele scoring. Each index considers all three genes as complementary components of a liver enzyme drug metabolism system and uniquely benchmarks innate hepatic drug metabolism reserve or alteration through CYP450 combinatory genotype scores. Methods A total of 1199 psychiatric referrals were genotyped for polymorphisms in the CYP2C9, CYP2C19 and CYP2D6 gene loci and were scored on each of the four indices. The data were used to create distributions and rankings of innate drug metabolism capacity to which individuals can be compared. Drug-specific indices are a combination of the drug metabolism indices with substrate-specific coefficients. Results The combinatory drug metabolism indices proved useful in positioning individuals relative to a population with regard to innate drug metabolism capacity prior to pharmacotherapy. Drug-specific indices generate pharmacogenetic guidance of immediate clinical relevance, and can be further modified to incorporate covariates in particular clinical cases. Conclusions We believe that this combinatory approach represents an improvement over the current gene-by-gene reporting by providing greater scope while still allowing for the resolution of a single-gene index when needed. This method will result in novel clinical and research applications, facilitating the translation from pharmacogenomics to personalized medicine, particularly in psychiatry where many drugs are metabolized or activated by multiple CYP450 isoenzymes. PMID:21861665

Pharmacokinetics and pharmacodynamics of the proton pump inhibitors.

PubMed

Shin, Jai Moo; Kim, Nayoung

2013-01-01

Proton pump inhibitor (PPI) is a prodrug which is activated by acid. Activated PPI binds covalently to the gastric H(+), K(+)-ATPase via disulfide bond. Cys813 is the primary site responsible for the inhibition of acid pump enzyme, where PPIs bind. Omeprazole was the first PPI introduced in market, followed by pantoprazole, lansoprazole and rabeprazole. Though these PPIs share the core structures benzimidazole and pyridine, their pharmacokinetics and pharmacodynamics are a little different. Several factors must be considered in understanding the pharmacodynamics of PPIs, including: accumulation of PPI in the parietal cell, the proportion of the pump enzyme located at the canaliculus, de novo synthesis of new pump enzyme, metabolism of PPI, amounts of covalent binding of PPI in the parietal cell, and the stability of PPI binding. PPIs have about 1hour of elimination half-life. Area under the plasmic concentration curve and the intragastric pH profile are very good indicators for evaluating PPI efficacy. Though CYP2C19 and CYP3A4 polymorphism are major components of PPI metabolism, the pharmacokinetics and pharmacodynamics of racemic mixture of PPIs depend on the CYP2C19 genotype status. S-omeprazole is relatively insensitive to CYP2C19, so better control of the intragastric pH is achieved. Similarly, R-lansoprazole was developed in order to increase the drug activity. Delayed-release formulation resulted in a longer duration of effective concentration of R-lansoprazole in blood, in addition to metabolic advantage. Thus, dexlansoprazole showed best control of the intragastric pH among the present PPIs. Overall, PPIs made significant progress in the management of acid-related diseases and improved health-related quality of life.

Future Trends in the Pharmacogenomics of Brain Disorders and Dementia: Influence of APOE and CYP2D6 Variants

PubMed Central

Cacabelos, Ramón; Fernández-Novoa, Lucía; Martínez-Bouza, Rocío; McKay, Adam; Carril, Juan C.; Lombardi, Valter; Corzo, Lola; Carrera, Iván; Tellado, Iván; Nebril, Laura; Alcaraz, Margarita; Rodríguez, Susana; Casas, Ángela; Couceiro, Verónica; Álvarez, Antón

2010-01-01

About 80% of functional genes in the human genome are expressed in the brain and over 1,200 different genes have been associated with the pathogenesis of CNS disorders and dementia. Pharmacogenetic studies of psychotropic drug response have focused on determining the relationship between variations in specific candidate genes and the positive and adverse effects of drug treatment. Approximately, 18% of neuroleptics are substrates of CYP1A2 enzymes, 40% of CYP2D6, and 23% of CYP3A4; 24% of antidepressants are substrates of CYP1A2 enzymes, 5% of CYP2B6, 38% of CYP2C19, 85% of CYP2D6, and 38% of CYP3A4; 7% of benzodiazepines are substrates of CYP2C19 enzymes, 20% of CYP2D6, and 95% of CYP3A4. 10-20% of Western populations are defective in genes of the CYP superfamily; and the pharmacogenomic response of psychotropic drugs also depends on genetic variants associated with dementia. Prospective studies with anti-dementia drugs or with multifactorial strategies have revealed that the therapeutic response to conventional drugs in Alzheimer’s disease is genotype-specific. The disease-modifying effects (cognitive performance, biomarker modification) of therapeutic intervention are APOE-dependent, with APOE-4 carriers acting as the worst responders (APOE-3/3 > APOE-3/4 > APOE-4/4). APOE-CYP2D6 interactions also influence the therapeutic outcome in patients with dementia.

Effects of Rolapitant Administered Intravenously on the Pharmacokinetics of a Modified Cooperstown Cocktail (Midazolam, Omeprazole, Warfarin, Caffeine, and Dextromethorphan) in Healthy Subjects.

PubMed

Wang, Xiaodong; Zhang, Zhi-Yi; Arora, Sujata; Wang, Jing; Lu, Sharon; Powers, Dan; Kansra, Vikram

2018-04-25

Rolapitant is a selective, long-acting neurokinin-1 receptor antagonist, approved in the United States and Europe for prevention of delayed chemotherapy-induced nausea and vomiting in adults. This open-label study evaluated the effects of a new intravenous formulation of rolapitant on cytochrome P450 (CYP) enzyme (CYP3A, CYP1A2, CYP2C9, CYP2C19, and CYP2D6) activity. On days 1 and 14, 36 healthy volunteers received a modified Cooperstown cocktail (midazolam 3 mg [CYP3A substrate], caffeine 200 mg [CYP1A2 substrate], S-warfarin 10 mg [CYP2C9 substrate] + vitamin K 10 mg, omeprazole 40 mg [CYP2C19 substrate], and dextromethorphan 30 mg [CYP2D6 substrate]). On day 7, subjects received the modified Cooperstown cocktail after 166.5-mg rolapitant infusion. On days 21, 28, and 35, subjects received oral dextromethorphan. Maximum plasma concentration (C max ) and area under the plasma concentration-time curve (AUC 0-last ) of probe drugs post- vs pre-rolapitant administration were assessed using geometric least-squares mean ratios (GMRs) with 90%CIs. The 90%CIs of the GMRs were within the 0.80-1.25 no-effect limits for caffeine and S-warfarin C max and AUC 0-last . For midazolam C max and AUC 0-last and omeprazole C max , the 90%CIs of the GMRs were marginally outside these limits. Intravenous rolapitant coadministration increased dextromethorphan exposure, peaking 14 days post-rolapitant administration (GMRs: C max , 2.74, 90%CI 2.21-3.40; AUC 0-last , 3.36, 90%CI 2.74-4.13). Intravenous rolapitant 166.5 mg and probe drugs were well tolerated when coadministered. These data suggest that intravenous rolapitant is not an inhibitor of CYP3A, CYP2C9, CYP2C19, or CYP1A2 but is a moderate inhibitor of CYP2D6. © 2018, The American College of Clinical Pharmacology.

CYP1A1 and CYP1A2 expression: Comparing 'humanized' mouse lines and wild-type mice; comparing human and mouse hepatoma-derived cell lines

DOE Office of Scientific and Technical Information (OSTI.GOV)

Uno, Shigeyuki; Endo, Kaori; Ishida, Yuji

2009-05-15

Human and rodent cytochrome P450 (CYP) enzymes sometimes exhibit striking species-specific differences in substrate preference and rate of metabolism. Human risk assessment of CYP substrates might therefore best be evaluated in the intact mouse by replacing mouse Cyp genes with human CYP orthologs; however, how 'human-like' can human gene expression be expected in mouse tissues? Previously a bacterial-artificial-chromosome-transgenic mouse, carrying the human CYP1A1{sub C}YP1A2 locus and lacking the mouse Cyp1a1 and Cyp1a2 orthologs, was shown to express robustly human dioxin-inducible CYP1A1 and basal versus inducible CYP1A2 (mRNAs, proteins, enzyme activities) in each of nine mouse tissues examined. Chimeric mice carryingmore » humanized liver have also been generated, by transplanting human hepatocytes into a urokinase-type plasminogen activator(+/+){sub s}evere-combined-immunodeficiency (uPA/SCID) line with most of its mouse hepatocytes ablated. Herein we compare basal and dioxin-induced CYP1A mRNA copy numbers, protein levels, and four enzymes (benzo[a]pyrene hydroxylase, ethoxyresorufin O-deethylase, acetanilide 4-hydroxylase, methoxyresorufin O-demethylase) in liver of these two humanized mouse lines versus wild-type mice; we also compare these same parameters in mouse Hepa-1c1c7 and human HepG2 hepatoma-derived established cell lines. Most strikingly, mouse liver CYP1A1-specific enzyme activities are between 38- and 170-fold higher than human CYP1A1-specific enzyme activities (per unit of mRNA), whereas mouse versus human CYP1A2 enzyme activities (per unit of mRNA) are within 2.5-fold of one another. Moreover, both the mouse and human hepatoma cell lines exhibit striking differences in CYP1A mRNA levels and enzyme activities. These findings are relevant to risk assessment involving human CYP1A1 and CYP1A2 substrates, when administered to mice as environmental toxicants or drugs.« less

Geneva cocktail for cytochrome p450 and P-glycoprotein activity assessment using dried blood spots.

PubMed

Bosilkovska, M; Samer, C F; Déglon, J; Rebsamen, M; Staub, C; Dayer, P; Walder, B; Desmeules, J A; Daali, Y

2014-09-01

The suitability of the capillary dried blood spot (DBS) sampling method was assessed for simultaneous phenotyping of cytochrome P450 (CYP) enzymes and P-glycoprotein (P-gp) using a cocktail approach. Ten volunteers received an oral cocktail capsule containing low doses of the probes bupropion (CYP2B6), flurbiprofen (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), midazolam (CYP3A), and fexofenadine (P-gp) with coffee/Coke (CYP1A2) on four occasions. They received the cocktail alone (session 1), and with the CYP inhibitors fluvoxamine and voriconazole (session 2) and quinidine (session 3). In session 4, subjects received the cocktail after a 7-day pretreatment with the inducer rifampicin. The concentrations of probes/metabolites were determined in DBS and plasma using a single liquid chromatography-tandem mass spectrometry method. The pharmacokinetic profiles of the drugs were comparable in DBS and plasma. Important modulation of CYP and P-gp activities was observed in the presence of inhibitors and the inducer. Minimally invasive one- and three-point (at 2, 3, and 6 h) DBS-sampling methods were found to reliably reflect CYP and P-gp activities at each session.

Geneva Cocktail for Cytochrome P450 and P-Glycoprotein Activity Assessment Using Dried Blood Spots

PubMed Central

Bosilkovska, M; Samer, C F; Déglon, J; Rebsamen, M; Staub, C; Dayer, P; Walder, B; Desmeules, J A; Daali, Y

2014-01-01

The suitability of the capillary dried blood spot (DBS) sampling method was assessed for simultaneous phenotyping of cytochrome P450 (CYP) enzymes and P-glycoprotein (P-gp) using a cocktail approach. Ten volunteers received an oral cocktail capsule containing low doses of the probes bupropion (CYP2B6), flurbiprofen (CYP2C9), omeprazole (CYP2C19), dextromethorphan (CYP2D6), midazolam (CYP3A), and fexofenadine (P-gp) with coffee/Coke (CYP1A2) on four occasions. They received the cocktail alone (session 1), and with the CYP inhibitors fluvoxamine and voriconazole (session 2) and quinidine (session 3). In session 4, subjects received the cocktail after a 7-day pretreatment with the inducer rifampicin. The concentrations of probes/metabolites were determined in DBS and plasma using a single liquid chromatography–tandem mass spectrometry method. The pharmacokinetic profiles of the drugs were comparable in DBS and plasma. Important modulation of CYP and P-gp activities was observed in the presence of inhibitors and the inducer. Minimally invasive one- and three-point (at 2, 3, and 6 h) DBS-sampling methods were found to reliably reflect CYP and P-gp activities at each session. PMID:24722393

A Novel Multifunctional C-23 Oxidase, CYP714E19, is Involved in Asiaticoside Biosynthesis.

PubMed

Kim, Ok Tae; Um, Yurry; Jin, Mei Lan; Kim, Jang Uk; Hegebarth, Daniela; Busta, Lucas; Racovita, Radu C; Jetter, Reinhard

2018-06-01

Centella asiatica is widely used as a medicinal plant due to accumulation of the ursane-type triterpene saponins asiaticoside and madecassoside. The molecular structure of both compounds suggests that they are biosynthesized from α-amyrin via three hydroxylations, and the respective Cyt P450-dependent monooxygenases (P450 enzymes) oxidizing the C-28 and C-2α positions have been reported. However, a third enzyme hydroxylating C-23 remained elusive. We previously identified 40,064 unique sequences in the transcriptome of C. asiatica elicited by methyl jasmonate, and among them we have now found 149 unigenes encoding putative P450 enzymes. In this set, 23 full-length cDNAs were recognized, 13 of which belonged to P450 subfamilies previously implicated in secondary metabolism. Four of these genes were highly expressed in response to jasmonate treatment, especially in leaves, in accordance with the accumulation patterns of asiaticoside. The functions of these candidate genes were tested using heterologous expression in yeast cells. Gas chromatography-mass spectrometry (GC-MS) analysis revealed that yeast expressing only the oxidosqualene synthase CaDDS produced the asiaticoside precursor α-amyrin (along with its isomer β-amyrin), while yeast co-expressing CaDDS and CYP716A83 also contained ursolic acid along with oleanolic acid. This P450 enzyme thus acts as a multifunctional triterpenoid C-28 oxidase converting amyrins into corresponding triterpenoid acids. Finally, yeast strains co-expressing CaDDS, CYP716A83 and CYP714E19 produced hederagenin and 23-hydroxyursolic acid, showing that CYP714E19 is a multifunctional triterpenoid oxidase catalyzing the C-23 hydroxylation of oleanolic acid and ursolic acid. Overall, our results demonstrate that CaDDS, CYP716A83 and CYP714E19 are C. asiatica enzymes catalyzing consecutive steps in asiaticoside biosynthesis.

Organophosphorothionate pesticides inhibit the bioactivation of imipramine by human hepatic cytochrome P450s

DOE Office of Scientific and Technical Information (OSTI.GOV)

Di Consiglio, Emma; Meneguz, Annarita; Testai, Emanuela

2005-06-15

The drug-toxicant interaction between the antidepressant imipramine (IMI) and three organophosphorothionate pesticides (OPTs), to which humans may be chronically and simultaneously exposed, has been investigated in vitro. Concentrations of IMI (2-400 {mu}M) and OPTs ({<=}10 {mu}M) representative of actual human exposure have been tested with recombinant human CYPs and human liver microsomes (HLM). The different CYPs involved in IMI demethylation to the pharmacologically active metabolite desipramine (DES) were CYP2C19 > CYP1A2 > CYP3A4. The OPTs significantly inhibited (up to >80%) IMI bioactivation catalyzed by the recombinant CYPs tested, except CYP2D6, and by HLM; the inhibition was dose-dependent and started atmore » low pesticide concentrations (0.25-2.5 {mu}M). The OPTs, having lower K {sub m} values, efficiently competed with IMI for the enzyme active site, as in the case of CYP2C19. However, with CYP1A2 and CYP3A4, a time- and NADPH-dependent mechanism-based inactivation also occurred, consistently with irreversible inhibition due to the release of the sulfur atom, binding to the active CYP during OPT desulfuration. At low IMI and OPT concentrations, lower IC50 values have been obtained with recombinant CYP1A2 (0.7-1.1 {mu}M) or with HLM rich in 1A2-related activity (2-10.8 {mu}M). The K {sub i} values (2-14 {mu}M), independent on substrate concentrations, were quite low and similar for the three pesticides. Exposure to OPTs during IMI therapeutic treatments may lead to decreased DES formation, resulting in high plasma levels of the parent drug, eventual impairment of its pharmacological action and possible onset of adverse drug reactions (ADRs)« less

Pharmacogenetic Selection of Volunteers Increases Stringency of Bioequivalence Studies; The Case of Clopidogrel

PubMed Central

Garcés-Eisele, J.; Ruiz-Argüelles, A.; Estrada-Marín, Larisa; Reyes-Núñez, Virginia; Vázquez-Pérez, R.; Guzmán-García, Olga; Coutiño-Medina, R.; Acosta-Sandria, Leticia; Cedillo-Carvallo, Beatriz

2014-01-01

Clinical response to clopidogrel varies widely due to under-dosing, drug interactions and intrinsic interindividual differences resulting from genetic polymorphisms. Cytochrome P450-2C19 is the principal enzyme involved in the activation of the prodrug and loss-of-function alleles have been described. Upon expiration of the pharmaceutical patent of clopidogrel, generic manufacturers have started to subject interchangeable formulations to bioequivalence studies. The purpose of the current investigation was to study the effect of selection of volunteers homozygous for the CYP2C19*1 haplotype on the bioavailability of clopidogrel. A regular 2×2 bioequivalence study between two formulations of clopidogrel was performed in volunteers selected and unselected for relevant CYP2C19 haplotypes for the Mexican population. It was found that selection of volunteers homozygous for the CYP2C19*1 haplotype, increased the stringency of bioequivalence statistics and resulted in bioinequivalence of a generic clopidogrel compound that otherwise proved equivalent when tested in an open unselected population. Augmentation of bioequivalence strictness is expected to result from pharmacogenetic selection of volunteers. PMID:25284925

Identification of cytochrome P450s involved in the metabolism of 6-benzyl-1-benzyloxymethyl-5-iodouracil (W-1) using human recombinant enzymes and rat liver microsomes in vitro.

PubMed

Lu, Ying-Yuan; Cheng, Hai-Xu; Wang, Xin; Wang, Xiao-Wei; Liu, Jun-Yi; Li, Pu; Lou, Ya-Qing; Li, Jun; Lu, Chuang; Zhang, Guo-Liang

2017-08-01

1. The aim of this study was to identify the hepatic metabolic enzymes, which involved in the biotransformation of 6-benzyl-1-benzyloxymethyl-5-iodouracil (W-1), a novel non-nucleoside reverse transcriptase inhibitor (NNRTI) in rat and human in vitro. 2. The parent drug of W-1 was incubated with rat liver microsomes (RLMs) or recombinant CYPs (CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4, and CYP3A5, respectively) in the presence or absence of nicotinamide adeninedinucleotide phosphate (NADPH)-regenerating system. The metabolites of W-1 were analyzed with liquid chromatography-ion trap-time of flight-mass spectrometry (LC-IT-TOF-MS). 3. The parent drug of W-1 was metabolized in a NADPH-dependent manner in RLMs. The kinetic parameters of prototype W-1 including K m , V max , and CL int were 2.3 μM, 3.3 nmol/min/mg protein, and 1.4 mL/min/mg protein, respectively. Two metabolites M1 and M2 were observed in shorter retention times (2.988 and 3.188 min) with a higher molecular ion at m/z 463.0160 (both M1 and M2) than that of the W-1 parent drug (6.158 min with m/z 447.0218). The CYP selective inhibition and recombinant enzymes also showed that two hydroxyl metabolites M1 and M2 are mainly mediated by CYP2C19 and CYP3A4. 4. The identification of CYPs involved in W-1 biotransformation is important to understand and minimize, if possible, the potential of drug-drug interactions.

CYP450 phenotyping and accurate mass identification of metabolites of the 8-aminoquinoline, anti-malarial drug primaquine.

PubMed

Pybus, Brandon S; Sousa, Jason C; Jin, Xiannu; Ferguson, James A; Christian, Robert E; Barnhart, Rebecca; Vuong, Chau; Sciotti, Richard J; Reichard, Gregory A; Kozar, Michael P; Walker, Larry A; Ohrt, Colin; Melendez, Victor

2012-08-02

The 8-aminoquinoline (8AQ) drug primaquine (PQ) is currently the only approved drug effective against the persistent liver stage of the hypnozoite forming strains Plasmodium vivax and Plasmodium ovale as well as Stage V gametocytes of Plasmodium falciparum. To date, several groups have investigated the toxicity observed in the 8AQ class, however, exact mechanisms and/or metabolic species responsible for PQ's haemotoxic and anti-malarial properties are not fully understood. In the present study, the metabolism of PQ was evaluated using in vitro recombinant metabolic enzymes from the cytochrome P450 (CYP) and mono-amine oxidase (MAO) families. Based on this information, metabolite identification experiments were performed using nominal and accurate mass measurements. Relative activity factor (RAF)-weighted intrinsic clearance values show the relative role of each enzyme to be MAO-A, 2C19, 3A4, and 2D6, with 76.1, 17.0, 5.2, and 1.7% contributions to PQ metabolism, respectively. CYP 2D6 was shown to produce at least six different oxidative metabolites along with demethylations, while MAO-A products derived from the PQ aldehyde, a pre-cursor to carboxy PQ. CYPs 2C19 and 3A4 produced only trace levels of hydroxylated species. As a result of this work, CYP 2D6 and MAO-A have been implicated as the key enzymes associated with PQ metabolism, and metabolites previously identified as potentially playing a role in efficacy and haemolytic toxicity have been attributed to production via CYP 2D6 mediated pathways.

Is toxicity of PMMA (paramethoxymethamphetamine) associated with cytochrome P450 pharmacogenetics?

PubMed

Vevelstad, Merete; Øiestad, Elisabeth Leere; Bremer, Sara; Bogen, Inger Lise; Zackrisson, Anna-Lena; Arnestad, Marianne

2016-04-01

In 2010-2013, 29 fatal intoxications related to the designer drug paramethoxymethamphetamine (PMMA, 4-methoxymethamphetamine) occurred in Norway. The current knowledge about metabolism and toxicity of PMMA in humans is limited. Metabolism by the polymorphic cytochrome P450 (CYP) 2D6 enzyme to the psychoactive metabolite 4-hydroxymethamphetamine (OH-MA), and possibly by additional enzymes, is suggested to be involved in its toxicity. The aim of this work was to study the association between CYP genetics, PMMA metabolism and risk of fatal PMMA toxicity in humans. The frequency distribution of clinically relevant gene variants of CYP2D6, CYP2C9, CYP2C19 and CYP3A5, and the phenotypic blood CYP2D6 metabolic ratio (OH-MA/PMMA) in particular, were compared in fatal PMMA intoxications (n=17) and nonfatal PMMA abuse controls (n=30), using non-abusers (n=305) as references for the expected genotype frequencies in the Norwegian population. Our study demonstrated that the CYP2D6 enzyme and genotype are important in the metabolism of PMMA to OH-MA in humans, but that other enzymes are also involved in this biotransformation. In the fatal PMMA intoxications, the blood concentrations of PMMA were higher and the CYP2D6 metabolic ratios were lower, than in the nonfatal PMMA abuse controls (median (range) 2.1 (0.03-5.0) vs 0.3 (0.1-0.9) mg/L, and ratio 0.6 (0.0-4.6) vs 2.1 (0.2-7.4) p=0.021, respectively). Overall, our findings indicated that, in most cases, PMMA death occurred rapidly and at an early stage of PMMA metabolism, following the ingestion of large and toxic PMMA doses. We could not identify any genetic CYP2D6, CYP2C9, CYP2C19 or CYP3A5 predictive marker on fatal toxicity of PMMA in humans. The overrepresentation of the CYP2D6 poor metabolizer (PM) genotype found in the nonfatal PMMA abuse controls warrants further investigations. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Effect of anti-tuberculosis therapy on polymorphic drug metabolizing enzyme CYP2C9 using phenytoin as a probe drug

PubMed Central

George, Melvin; Shewade, Deepak Gopal; Kumar, Saka Vinod; Adithan, Chandrasekaran

2012-01-01

Objectives: Patients on anti-tuberculosis therapy (ATT) are more prone to drug interactions in the presence of coexisting illnesses which warrant drug therapy. Rifampicin is a strong CYP enzyme inducer while isoniazid is a potent CYP inhibitor. The objective of the study was to find the net effect of one month ATT on CYP2C9 enzyme and to correlate it with respect to the CYP2C9 genetic polymorphisms. Materials and Methods: Forty eight newly diagnosed tuberculosis patients were included in the study based on the inclusion-exclusion criteria. Before commencing ATT, they were given a single dose of phenytoin 300 mg as a probe drug for CYP2C9. Blood sample was collected after three hours to carry out CYP2C9 genotyping by PCR-RFLP method. Phenotyping for CYP2C9 enzyme was done by measuring the ratio of phenytoin and its metabolite p-HPPH (para hydroxy phenyl hydantoin) by reverse phase HPLC (high performance liquid chromatography) method before and after one month of ATT. Results: In the CYP2C9*1*1 genotype, the mean plasma concentrations of phenytoin before and after one month of ATT were 5.2 ± 0.3 μg/ml and 3.5 ± 0.4 μg/ml respectively, a reduction by 33% showing significant induction (P < 0.001). There was also significant decrease in the metabolic ratio after one month of ATT from 23.2 ± 4.8 to 10.1 ± 1.9 (P < 0.001). The metabolic ratio was also observed to reduce significantly (P < 0.05) when the CYP2C9*1*2, CYP2C9*1*3, and CYP2C9*3*3 data were pooled together. Conclusion: The presence of polymorphisms in the CYP2C9 gene does not affect the induction potential of ATT. PMID:23087510

Dose of Phenobarbital and Age of Treatment at Early Life are Two Key Factors for the Persistent Induction of Cytochrome P450 Enzymes in Adult Mouse Liver

PubMed Central

Tien, Yun-Chen; Liu, Ke; Pope, Chad; Wang, Pengcheng; Ma, Xiaochao

2015-01-01

Drug treatment of neonates and infants and its long-term consequences on drug responses have emerged in recent years as a major challenge for health care professionals. In the current study, we use phenobarbital as a model drug and mouse as an in vivo model to demonstrate that the dose of phenobarbital and age of treatment are two key factors for the persistent induction of gene expression and consequential increases of enzyme activities of Cyp2b, Cyp2c, and Cyp3a in adult livers. We show that phenobarbital treatment at early life of day 5 after birth with a low dose (<100 mg/kg) does not change expression and enzyme activities of Cyp2b, Cyp2c, and Cyp3a in adult mouse liver, whereas phenobarbital treatment with a high dose (>200 mg/kg) significantly increases expression and enzyme activities of these P450s in adult liver. We also demonstrate that phenobarbital treatment before day 10 after birth, but not at later ages, significantly increases mRNAs, proteins, and enzyme activities of the tested P450s. Such persistent induction of P450 gene expression and enzyme activities in adult livers by phenobarbital treatment only occurs within a sensitive age window early in life. The persistent induction in gene expression and enzyme activities is higher in female mice than in male mice for Cyp2b10 but not for Cyp2c29 and Cyp3a11. These results will stimulate studies to evaluate the long-term impacts of drug treatment with different doses at neonatal and infant ages on drug metabolism, therapeutic efficacy, and drug-induced toxicity throughout the rest of life. PMID:26400395

Inhibitory effects of cytostatically active 6-aminobenzo[c]phenanthridines on cytochrome P450 enzymes in human hepatic microsomes.

PubMed

Zebothsen, Inga; Kunze, Thomas; Clement, Bernd

2006-07-01

Besides assays for the evaluation of efficacy new drug candidates have to undergo extensive testings for enhancement of pharmaceutical drug safety and optimization of application. The objective of the present work was to investigate the pharmacokinetic drug drug interaction potential for the cytostatically active 6-aminobenzo[c]phenanthridines BP-11 (6-amino-11,12-dihydro-11-(4-hydroxy-3,5-dimethoxyphenyl)benzo[c]phenanthridine) and BP-D7 (6-amino-11-(3,4,5-trimethoxyphenyl)benzo[c]phenanthridine) in vitro through incubation with human hepatic microsomes and marker substrates. For these studies the cytochrome P-450 isoenzymes and corresponding marker substrates recommended by the EMEA (The European Agency for the Evaluation of Medicinal Products) were chosen. In detail these selective substrates were caffeine (CYP1A2), coumarin (CYP2A6), tolbutamide (CYP2C9), S-(+)-mephenytoin (CYP2C19), dextromethorphane (CYP2D6), chlorzoxazone (CYP2E1) and testosterone (CYP3A4). Incubations with each substrate were carried out without a possible inhibitor and in the presence of a benzo[c]phenanthridine or a selective inhibitor at varying concentrations. Marker activities were determined by HPLC (high performance liquid chromatography). For the isoenzymes showing more than 50% inhibition by the addition of 20 microM BP-11 or BP-D7 additional concentrations of substrate and inhibitor were tested for a characterization of the inhibition. The studies showed a moderate risk for BP-11 for interactions with the cytochrome P-450 isoenzymes CYP1A2, CYP2C9, CYP2D6 and CYP3A4. BP-D7, the compound with the highest cytotstatic efficacy, showed only a moderate risk for interactions with drugs, also metabolized by CYP3A4.

CYP2C19 genetic variation and individualized clopidogrel prescription in a cardiology clinic.

PubMed

Mirabbasi, Seyed Abbas; Khalighi, Koroush; Wu, Yin; Walker, Stanley; Khalighi, Bahar; Fan, Wuqiang; Kodali, Archana; Cheng, Gang

2017-07-01

Background : Clopidogrel (Plavix) is an antiplatelet medication that is routinely used in patients with cardiovascular disease. Cytochrome P2C19 enzymes play a major role in its metabolism, which determines its varied therapeutic level and its effectiveness. Objectives : To customize clopidogrel therapy and evaluate its efficacy by using CYP2C19 genotypic and phenotypic information to improve clinical outcomes in patients. Methods : A total of 465 patients with underlying cardiovascular disease were selected from our out-patient cardiology clinic. DNA sequences of CYP2C19 were analyzed in 465 patients. Results : Of 465 patients, 183 were wild-type homozygous (*1/*1) and 18.8% gain-of function and 19.8% loss-of-function alleles in our patient population The following changes were made: 1) Switching to prasugrel in patients whose genotype noted them to be "Slow metabolizers. This medication adjustment improved clinical outcomes in this patient group. 2) Discontinuing or lowering clopidogrel doses in patients whose genotypes noted them to be "Fast or ultra-fast metabolizes" to decrease bleeding risk. For those who were not on clopidogrel but carried abnormal allele(s), "clopidogrel caution" was documented. These individuals were followed up for 3 years and there has not been any cardiac clinical symptoms, cardiac death or excessive bleeding reported. Conclusions : Given the varied effectiveness of clopidogrel due to its metabolism by CYP2C19 enzyme, and the relatively high frequency of both gain-of-function (18.8%) and loss-of-function (19.8%) alleles in our patient population, we believe that genotyping CYP2C19 is clinically important in order to improve patient outcomes and minimize patient risk.

Complementary DNA cloning, functional expression and characterization of a novel cytochrome P450, CYP2D50, from equine liver.

PubMed

DiMaio Knych, H K; Stanley, S D

2008-10-01

Members of the CYP2D family constitute only about 2-4% of total hepatic CYP450s, however, they are responsible for the metabolism of 20-25% of commonly prescribed therapeutic compounds. CYP2D enzymes have been identified in a number of different species. However, vast differences in the metabolic activity of these enzymes have been well documented. In the horse, the presence of a member of the CYP2D family has been suggested from studies with equine liver microsomes, however its presence has not been definitively proven. In this study a cDNA encoding a novel CYP2D enzyme (CYP2D50) was cloned from equine liver and expressed in a baculovirus expression system. The nucleotide sequence of CYP2D50 was highly homologous to that of human CYP2D6 and therefore the activity of the enzyme was characterized using dextromethorphan and debrisoquine, two isoform selective substrates for the human orthologue. CYP2D50 displayed optimal catalytic activity with dextromethorphan using molar ratios of CYP2D50 to NADPH CYP450 reductase of 1:15. Although CYP2D50 and CYP2D6 shared significant sequence homology, there were striking differences in the catalytic activity between the two enzymes. CYP2D50 dextromethorphan-O-demethylase activity was nearly 180-fold slower than the human counterpart, CYP2D6. Similarly, rates of formation of 4-hydroxydebrisoquine activity were 50-fold slower for CYP2D50 compared to CYP2D6. The results of this study demonstrate substantial interspecies variability in metabolism of substrates by CYP2D orthologues in the horse and human and support the need to fully characterize this enzyme system in equids.

CYP1A1 and CYP1A2 expression: Comparing ‘humanized’ mouse lines and wild-type mice; comparing human and mouse hepatoma-derived cell lines

PubMed Central

Uno, Shigeyuki; Endo, Kaori; Ishida, Yuji; Tateno, Chise; Makishima, Makoto; Yoshizato, Katsutoshi; Nebert, Daniel W.

2009-01-01

Human and rodent cytochrome P450 (CYP) enzymes sometimes exhibit striking species-specific differences in substrate preference and rate of metabolism. Human risk assessment of CYP substrates might therefore best be evaluated in the intact mouse by replacing mouse Cyp genes with human CYP orthologs; however, how “human-like” can human gene expression be expected in mouse tissues? Previously a bacterial-artificial-chromosome-transgenic mouse, carrying the human CYP1A1_CYP1A2 locus and lacking the mouse Cyp1a1 and Cyp1a2 orthologs, was shown to express robustly human dioxin-inducible CYP1A1 and basal versus inducible CYP1A2 (mRNAs, proteins, enzyme activities) in each of nine mouse tissues examined. Chimeric mice carrying humanized liver have also been generated, by transplanting human hepatocytes into a urokinase-type plasminogen activator(+/+)_severe-combined-immunodeficiency (uPA/SCID) line with most of its mouse hepatocytes ablated. Herein we compare basal and dioxin-induced CYP1A mRNA copy numbers, protein levels, and four enzymes (benzo[a]pyrene hydroxylase, ethoxyresorufin O-deethylase, acetanilide 4-hydroxylase, methoxyresorufin O-demethylase) in liver of these two humanized mouse lines versus wild-type mice; we also compare these same parameters in mouse Hepa-1c1c7 and human HepG2 hepatoma-derived established cell lines. Most strikingly, mouse liver CYP1A1-specific enzyme activities are between 38- and 170-fold higher than human CYP1A1-specific enzyme activities (per unit of mRNA), whereas mouse versus human CYP1A2 enzyme activities (per unit of mRNA) are within 2.5-fold of one another. Moreover, both the mouse and human hepatoma cell lines exhibit striking differences in CYP1A mRNA levels and enzyme activities. These findings are relevant to risk assessment involving human CYP1A1 and CYP1A2 substrates, when administered to mice as environmental toxicants or drugs. PMID:19285097

Mangifera indica L. extract and mangiferin modulate cytochrome P450 and UDP-glucuronosyltransferase enzymes in primary cultures of human hepatocytes.

PubMed

Rodeiro, Idania; José Gómez-Lechón, M; Perez, Gabriela; Hernandez, Ivones; Herrera, José Alfredo; Delgado, Rene; Castell, José V; Teresa Donato, M

2013-05-01

The aqueous stem bark extract of Mangifera indica L. (MSBE) has been reported to have antioxidant, anti-inflammatory and analgesic properties. In previous studies, we showed that MSBE and mangiferin, its main component, lower the activity of some cytochrome P-450 (P450) enzymes in rat hepatocytes and human liver microsomes. In the present study, the effects of MSBE and mangiferin on several P450 enzymes and UDP-glucuronosyltransferases (UGTs) in human-cultured hepatocytes have been examined. After hepatocytes underwent a 48-h treatment with sub-cytotoxic concentrations of the products (50-250 µg/mL), a concentration-dependent decrease of the activity of the five P450 enzymes measured (CYP1A2, 2A6, 2C9, 2D6 and 3A4) was observed. For all the activities, a reduction of at least 50% at the highest concentration (250 µg/mL) was observed. In addition, UGT activities diminished. MSBE considerably reduced UGT1A9 activity (about 60% at 250 µg/mL) and lesser effects on the other UGTs. In contrast, 250 µg/mL mangiferin had greater effects on UGT1A1 and 2B7 than on UGT1A9 (about 55% vs. 35% reduction, respectively). Quantification of specific mRNAs revealed reduced CYP3A4 and 3A5 mRNAs content, and an increase in CYP1A1, CYP1A2, UGT1A1 and UGT1A9 mRNAs. No remarkable effects on the CYP2A6, 2B6, 2C9, 2C19, 2D6 and 2E1 levels were observed. Our results suggest that the activity and/or expression of major P450 and UGT enzymes is modulated by MSBE and that potential herb-drugs interactions could arise after a combined intake of this extract with conventional medicines. Therefore, the potential safety risks of this natural product derived by altering the ADMET properties of co-administered drugs should be examined. Copyright © 2012 John Wiley & Sons, Ltd.

Pharmacogenetics of drug-drug interaction and drug-drug-gene interaction: a systematic review on CYP2C9, CYP2C19 and CYP2D6.

PubMed

Bahar, Muh Akbar; Setiawan, Didik; Hak, Eelko; Wilffert, Bob

2017-05-01

Currently, most guidelines on drug-drug interaction (DDI) neither consider the potential effect of genetic polymorphism in the strength of the interaction nor do they account for the complex interaction caused by the combination of DDI and drug-gene interaction (DGI) where there are multiple biotransformation pathways, which is referred to as drug-drug-gene interaction (DDGI). In this systematic review, we report the impact of pharmacogenetics on DDI and DDGI in which three major drug-metabolizing enzymes - CYP2C9, CYP2C19 and CYP2D6 - are central. We observed that several DDI and DDGI are highly gene-dependent, leading to a different magnitude of interaction. Precision drug therapy should take pharmacogenetics into account when drug interactions in clinical practice are expected.

Potential herb-drug interaction of shexiang baoxin pill in vitro based on drug metabolism/transporter

PubMed Central

Shen, Zhijie; Wang, Yingjie; Guo, Wei; Yao, Yili; Wang, Xiaolong

2016-01-01

Many researches have proved functions of anti-oxidation, endothelial protection and pro-angiogenesis efficiency of Shexiang Baoxin Pill (SBP). This study aims to investigate potential for metabolism-based interaction on CYP450s and transporter based interaction on OATP1B1, BRCP and MDR1. Human primary hepatocytes were used in this study. Probe substrates of cytochrome P450 enzymes were incubated in human liver microsomes (HLMs) with or without SBP and IC50 values were estimated. Inhibitive potential of SBP on activities of CYP1A2, 2B6, 2C8, 2C9, 2C19, 2D6 and 3A4 was evaluated. Inducible potential of SBP on activities of CYP1A2, 2B6 and 3A4 was accessed. Inhibitive potential of SBP on human OATP1B1 was evaluated using cell-based assay. Inhibitive potential of SBP on human MDR1 and BCRP was also evaluated using vesicles assay. MDR1 and BCRP vesicle kit were used to determine ATP dependent uptake activity when incubated with SBP. SBP was a competitive inhibitor of CYP2B6, 2C19, while neither inhibitory nor inductive potentials toward other CYP450s were detected. No significant MDR1 inhibitory potential was estimated, while only high concentration of SBP (500 μg/ml) could inhibit activity of BCRP. Probe substrates Estradiol-17 β-glucuronide was incubated in HEK293-OATP1B1 and HEK293-MOCK cell system with different concentration of SBP and estimated IC50 was 179 μg/mL, which demonstrated a moderate inhibition potential against OATP1B1. In conclusion, outcome of this study suggests that SBP plays an important role in inhibition of CYP450 isozymes (including CYP2B6 and 2C9) and transporter OATP1B1. Therefore, precautions should be taken when using SBP for CYP and OATP-related herb-drug interactions. PMID:28078025

Assessment of a dry extract from milk thistle (Silybum marianum) for interference with human liver cytochrome-P450 activities.

PubMed

Doehmer, Johannes; Weiss, Gabriele; McGregor, Gerard P; Appel, Kurt

2011-02-01

The effect of a standardised dry extract from Silybum marianum (HEPAR-PASC®) on the enzyme kinetics of cytochrome-P450 isoenzymes (CYP) was investigated with primary human hepatocytes and human liver microsomes in order to assess the potential for drug-drug interactions. A cytotoxic effect on hepatocytes was observed at concentrations at and above 50 μg/ml. The EC(50) value was calculated to be 72.0 μg/ml. Therefore, the chosen test concentrations for CYP induction on human hepatocytes were 50, 10, and 1.5 μg/ml, which allowed for interpretation of the clinical significance of the data with a range of 50-1-fold c(max) at maximal recommended doses. No induction was observed at the lowest concentration of 1.5 μg/ml, which is close to c(max). The extract did not induce CYP 3A4 at any of the tested concentrations. A low or marginal induction of 1A2, 2B6, and 2E1 at the maximum concentration of 50 μg/ml was observed. CYP inhibition on human microsomes was tested at concentrations of 150, 15, and 1.5 μg/ml. No or minor CYP inhibition was observed for all CYPs tested at the lowest concentration of 1.5 μg/ml, i.e. CYPs 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4. At concentrations of 15 and 150 μg/ml the extract significantly inhibited CYP 2B6, 2C8, 2C9, 2C19, 2E1, and 3A4. In these cases, K(i) values were determined. All K(i) values exceeded c(max) by at least a factor of 10-fold. According to FDA regulations 1>c(max)/K(i)>0.1 indicates, that drug-drug interactions are possible for CYPs 2C8, and 2C9, but not likely, and are remote for CYPs 2C19, 2D6, and 3A4. Copyright © 2010 Elsevier Ltd. All rights reserved.

Impact of cytochrome P450 2C19 polymorphisms on citalopram/escitalopram exposure: a systematic review and meta-analysis.

PubMed

Chang, Ming; Tybring, Gunnel; Dahl, Marja-Liisa; Lindh, Jonatan D

2014-09-01

Citalopram and escitalopram, selective serotonin reuptake inhibitors, are primarily metabolized by cytochrome P450 (CYP) 2C19, which is a highly polymorphic enzyme known to cause inter-individual differences in pharmacokinetics. However, the impact of CYP2C19 polymorphisms on citalopram or escitalopram exposure has yet to be fully clarified, especially with regard to the quantitative impact of the CYP2C19*17 allele. The objective of this study was to quantify the effect of functional CYP2C19 allele variants on citalopram/escitalopram exposure. We performed a systematic review and meta-analysis with a structured search algorithm and eligibility criteria for including related studies, calculating the change of citalopram or escitalopram exposure associated with CYP2C19*2, *3, and *17 as compared with CYP2C19*1 using fixed-effect and random-effects models. Assessment of publication bias was performed by means of funnel plots and sensitivity analysis using meta-regressions. The pre-defined review protocol was registered at the PROSPERO international prospective register of systematic reviews, registration number CRD42013004106. Sixteen studies from 14 publications met the inclusion criteria. Eligible studies included 847 patients from psychiatric patient trials and 140 healthy subjects from pharmacokinetic studies. Compared to subjects with the EM/EM (CYP2C19*1/*1) genotype, the exposure to (es)citalopram increased by 95 % (95 % CI 40-149, p < 0.0001) in the poor metabolizer (PM)/PM (CYP2C19*2 or *3/*2 or *3), 30 % (95 % CI 4-55, p < 0.05) in the extensive metabolizer (EM)/PM (CYP2C19*1/*2 or *3), and 25 % (95 % CI 1-49, p < 0.05) in the ultrarapid metabolizer (UM)/PM (CYP2C19*17/*2 or *3) groups. In contrast, the exposure to (es)citalopram decreased by 36 % (95 % CI 27-46, p < 0.0001) in the UM/UM (CYP2C19*17/*17) and by 14 % (95 % CI 1-27, p < 0.05) in the UM/EM (CYP2C19*17/*1). This is the first meta-analysis based on a systematic review of accumulated information that addresses the relationship between CYP2C19 genotypes and the exposure to citalopram or escitalopram. All functional CYP2C19 genotype groups demonstrated significant effects on (es)citalopram exposure. The findings based on our pooled analysis are likely to help in understanding the inter-individual variability in the exposure to citalopram and escitalopram in psychiatric patients and to facilitate dose selection, particularly for the homozygous carriers of CYP2C19*2 or *3 (loss of function) and CYP2C19*17 (gain of function) alleles. The results could improve individualization of citalopram or escitalopram therapy and could also be used for physiologically based pharmacokinetic modeling as well as pharmacokinetic/pharmacodynamic modeling.

Lack of association between genetic polymorphisms of CYP3A4, CYP2C9 and CYP2C19 and antituberculosis drug-induced liver injury in a community-based Chinese population.

PubMed

Tang, Shao-Wen; Lv, Xiao-Zhen; Chen, Ru; Wu, Shan-Shan; Yang, Zhi-Rong; Chen, Da-Fang; Zhan, Si-Yan

2013-05-01

The precise pathogenic mechanism of antituberculosis (anti-TB) drug-induced liver injury (ATLI) is poorly understood. It may be associated with drug-metabolizing enzymes, such as cytochrome P450 (CYP) 3A4, CYP2C9 and CYP2C19. The aim of the present study was to explore the role of tagging single nucleotide polymorphisms (tSNPs) of CYP3A4, CYP2C9 and CYP2C19 in the risk of ATLI in a population-based anti-TB treatment cohort. A nested case-control study was designed. Each ATLI case was matched 1 : 4 with controls on the basis of age, gender, treatment history, disease severity and drug dosage. The tSNPs were selected using Haploview 4.2 based on the HapMap database of Han Chinese in Beijing and genotyped by TaqMan allelic discrimination technology. Eighty-nine patients with ATLI and 356 controls were included in the study. One tSNP in CYP3A4 (rs12333983), two in CYP2C9 (rs4918758, rs9332098) and two in CYP2C19 (rs11568732, rs4986894) were selected and genotyped. The minor allele frequencies of rs12333983, rs4918758, rs9332098, rs11568732 and rs4986894 were 36.0%, 41.4%, 1.1%, 5.7% and 35.7%, respectively, in the patients, compared with 31.7%, 42.9%, 3.4%, 8.9% and 35.1%, respectively, in the controls. No significant differences were observed in genotypes or allele frequencies of the five tSNPs between the two groups and none of the CYP2C9 or CYP2C19 haplotypes was significantly associated with the development of ATLI. Based on the Chinese anti-TB treatment cohort, we did not find a significant association between the risk of ATLI and genetic polymorphisms of CYP3A4, CYP2C9 and CYP2C19. None of the haplotypes exhibited a significant association with the development of ATLI in a Chinese tuberculosis population. © 2013 The Authors Clinical and Experimental Pharmacology and Physiology © 2013 Wiley Publishing Asia Pty Ltd.

Lack of effect of tofacitinib (CP-690,550) on the pharmacokinetics of the CYP3A4 substrate midazolam in healthy volunteers: confirmation of in vitro data

PubMed Central

Gupta, Pankaj; Alvey, Christine; Wang, Rong; Dowty, Martin E; Fahmi, Odette A; Walsky, Robert L; Riese, Richard J; Krishnaswami, Sriram

2012-01-01

AIMS To investigate inhibitive and inductive effects of tofacitinib (CP-690,550), a Janus kinase inhibitor, on CYP3A4 function via in vitro and in vivo studies. METHODS In vitro experiments were conducted to assess the inhibition and induction potential of tofacitinib for major drug metabolizing enzymes (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6 and CYP3A4). A phase 1, randomized, open-label, two-way crossover study (NCT00902460) was conducted to confirm the lack of inhibitive/inductive effect on a sensitive CYP3A4 substrate, midazolam, in healthy subjects. Midazolam pharmacokinetics were assessed over 24 h following single dose 2 mg administration prior to administering tofacitinib and after twice daily dosing of tofacitinib 30 mg for 6 days. The primary endpoint was midazolam area under the concentration–time profile, from time 0 to infinity (AUC(0,∞)). RESULTS In vitro studies demonstrated low potential for CYP inhibition (IC50 estimates tofacitinib >30 µm), CYP3A4 mRNA induction (observed at tofacitinib concentrations ≥25 µm) and no effect on enzymatic activity of CYP substrates. In the human study, AUC(0,∞) adjusted geometric mean ratio for midazolam plus tofacitinib to midazolam alone was 103.97% [90% confidence interval (CI) 95.57, 113.12], wholly within the pre-specified acceptance region (80, 125). The 90% CI for the ratio of adjusted geometric means of maximum plasma concentration (Cmax) (95.98, 108.87) was also wholly within this acceptance region. CONCLUSIONS These data confirm a lack of an inhibitive or inductive effect of tofacitinib on CYP3A activity in humans and, in conjunction with in vitro data, support the conclusion that tofacitinib is unlikely to influence the CYP enzyme system as a whole. PMID:22233204

Human induced pluripotent stem cell line with cytochrome P450 enzyme polymorphism (CYP2C19*2/CYP3A5*3C) generated from lymphoblastoid cells.

PubMed

Lee, Jaehun; Woo, Dong-Hun; Park, Han-Jin; Park, Kijung; Ko, Duck Sung; Kim, Jong-Hoon

2018-03-01

Cytochrome P450 (CYP) comprises a superfamily of monooxygenase responsible for the metabolism of xenobiotics and approximately 75% of drugs in use today. Thus, genetic polymorphisms in CYP genes contribute to interindividual differences in hepatic metabolism of drugs, affecting on individual drug efficacy and may cause adverse effects. Here, we generated a human induced pluripotent stem cell (hiPSC) line with pharmacologically important traits (CYP2C19*2/CYP3A5*3C), which are highly polymorphic in Asian from lymphoblastoid cells. This hiPSC line could be a valuable source for predicting individual drug responses in the drug screening process that uses hiPSC-derived somatic cells, including hepatocytes. Copyright © 2018 The Authors. Published by Elsevier B.V. All rights reserved.

CYP2C19*17 increases clopidogrel-mediated platelet inhibition but does not alter the pharmacokinetics of the active metabolite of clopidogrel.

PubMed

Pedersen, Rasmus Steen; Nielsen, Flemming; Stage, Tore Bjerregaard; Vinholt, Pernille Just; el Achwah, Alaa Bilal; Damkier, Per; Brosen, Kim

2014-11-01

The aim of the present study was to determine the impact of CYP2C19*17 on the pharmacokinetics and pharmacodynamics of the active metabolite of clopidogrel and the pharmacokinetics of proguanil. Thus, we conducted an open-label two-phase cross-over study in 31 healthy male volunteers (11 CYP2C19*1/*1, 11 CYP2C19*1/*17 and nine CYP2C19*17/*17). In Phase A, the pharmacokinetics of the derivatized active metabolite of clopidogrel (CAMD) and platelet function were determined after administration of a single oral dose of 600 mg clopidogrel (Plavix; Sanofi-Avensis, Horsholm, Denmark). In Phase B, the pharmacokinetics of proguanil and its metabolites cycloguanil and 4-chlorphenylbiguanide (4-CPB) were determined in 29 of 31 subjects after a single oral dose of 200 mg proguanil given as the combination drug Malarone (GlaxoSmithKline Pharma, Brondby, Denmark). Significant correlations were found between the area under the time-concentration curve (AUC0-∞ ) of CAMD and both the absolute ADP-induced P2Y12 receptor-activated platelet aggregation (r = -0.60, P = 0.0007) and the percentage inhibition of aggregation (r = 0.59, P = 0.0009). In addition, the CYP2C19*17/*17 and CYP2C19*1/*17 genotype groups had significantly higher percentage inhibition of platelet aggregation compared with the CYP2C19*1/*1 subjects (geometric mean percentage inhibition of 84%, 73% and 63%, respectively; P = 0.014). Neither the absolute ADP-induced P2Y12 receptor-activated platelet aggregation, exposure to CAMD nor the pharmacokinetic parameters of proguanil, cycloguanil and 4-CPB exhibited any significant differences among the genotype groups. In conclusion, carriers of CYP2C19*17 exhibit higher percentage inhibition of platelet aggregation, but do not have significantly lower absolute P2Y12 receptor-activated platelet aggregation or higher exposure to the active metabolite after a single oral administration of 600 mg clopidogrel. © 2014 Wiley Publishing Asia Pty Ltd.

The Metabolism of Clopidogrel: CYP2C19 Is a Minor Pathway.

PubMed

Ford, Neville F

2016-12-01

The major metabolic pathway of clopidogrel is conversion to carboxylic acid by an esterase (CES1), forming clopidogrelic acid (SR26334) that is inactive. There is agreement on the structure of the active metabolite; however, there are differing views about the mechanism of its formation. Sanofi studied the conversion of clopidogrel to the active metabolite using human liver microsomes. It was concluded that 2-oxo-clopidogrel was formed via CYP3A oxidation. From a subsequent in vitro study by Sankyo of the metabolism of clopidogrel using recombinant DNA CYPs, it was concluded that CYP2C19 was the major oxidative pathway. Such CYPs can give false-negative results particularly with drugs such as clopidogrel that have high first-pass metabolism in the enterocyte. CYP3A is present in the enterocyte but not CYP2C19. However, the view that clopidogrel is a CYP2C19 substrate was reinforced by a finding that omeprazole, a CYP2C19 inhibitor, reduced the ability of clopidogrel to inhibit platelet aggregation. The drug-drug interaction study of clopidogrel with omeprazole had the effect of reducing the area under the curve (AUC) of the clopidogrel active metabolite by 45%. However, a drug interaction study with a CYP3A inhibitor, grapefruit juice, caused a 6-fold reduction in the AUC of the active metabolite. Clopidogrel is therefore now considered to be primarily a CYP3A4/5 substrate. CYP2C19 has a minor role whose effect can be detected using a sensitive methodology such as platelet aggregometry. © 2016, The American College of Clinical Pharmacology.

Genetic markers in CYP2C19 and CYP2B6 for prediction of cyclophosphamide's 4‐hydroxylation, efficacy and side effects in Chinese patients with systemic lupus erythematosus

PubMed Central

Shu, Wenying; Guan, Su; Yang, Xiuyan; Liang, Liuqin; Li, Jiali; Chen, Zhuojia; Zhang, Yu; Chen, Lingyan

2015-01-01

Aims The aim of the study was to investigate the combined impact of genetic polymorphisms in key pharmacokinetic genes on plasma concentrations and clinical outcomes of cyclophosphamide (CPA) in Chinese patients with systemic lupus erythematosus (SLE). Methods One hundred and eighty nine Chinese SLE patients treated with CPA induction therapy (200 mg, every other day) were recruited and adverse reactions were recorded. After 4 weeks induction therapy, 128 lupus nephritis (LN) patients continued to CPA maintenance therapy (200–600 mg week–1) for 6 months, and their clinical outcomes were recorded. Blood samples were collected for CYP2C19, CYP2B6, GST and PXR polymorphism analysis, as well as CPA and its active metabolite (4‐hydroxycyclophosphamide (4‐OH‐CPA)) plasma concentration determination. Results Multiple linear regression analysis revealed that CYP2B6 ‐750 T > C (P < 0.001), −2320 T > C (P < 0.001), 15582C > T (P = 0.017), CYP2C19*2 (P < 0.001) and PXR 66034 T > C (P = 0.028) accounted for 47% of the variation in 4‐OH‐CPA plasma concentration. Among these variants, CYP2B6 ‐750 T > C and CYP2C19*2 were selected as the combination genetic marker because these two SNPs contributed the most to the inter‐individual variability in 4‐OH‐CPA concentration, accounting for 23.6% and 21.5% of the variation, respectively. Extensive metabolizers (EMs) (CYP2B6 ‐750TT, CYP2C19*1*1) had significantly higher median 4‐OH‐CPA plasma concentrations (34.8, 11.0 and 6.6 ng ml‐1 for EMs, intermediate metabolizers (IMs) and poor metabolizers (PMs), P < 0.0001), higher risks of leukocytopenia (OR = 7.538, 95% CI 2.951, 19.256, P < 0.0001) and gastrointestinal toxicity (OR = 7.579, 95% CI 2.934, 19.578, P < 0.0001), as well as shorter median time to achieve complete remission (13.2, 18.3 and 23.3 weeks for EMs, IMs and PMs, respectively, P = 0.026) in LN patients than PMs (CYP2B6 ‐750CC, CYP2C19*2*2) and IMs. Conclusions Our findings have indicated that genetic markers of drug metabolizing enzymes could predict the 4‐hydroxylation, adverse reactions and clinical efficacy of CPA. This is a necessary first step towards building clinical tools that will help assess clinical benefit and risk before undergoing CPA treatment in Chinese SLE patients. PMID:26456622

The guinea-pig expresses functional CYP2C and P-glycoprotein: further validation of its usefulness in drug biotransformation/transport studies.

PubMed

Hasibu, Ibrahim; Patoine, Dany; Pilote, Sylvie; Drolet, Benoit; Simard, Chantale

2015-04-01

The guinea-pig is an excellent animal model for studying cardiopulmonary physiology/pharmacology. Interestingly, it also possesses a number of drug-metabolizing enzymes found in humans, such as CYP1A, CYP2D and CYP3A. To evaluate the hypothesis that the guinea-pig also expresses a functional CYP2C drug-metabolizing enzyme and the P-glycoprotein (P-gp) drug transporter in various tissues. cDNAs encoding CYP2C and P-gp were obtained from guinea-pig liver or small intestine and sequenced. Western blotting was performed to confirm the expression of CYP2C and P-gp. The functional enzymatic activity of guinea-pig CYP2C was evaluated with microsomal preparations using diclofenac and tolbutamide as specific drug substrates in HPLC analyses. To further study both P-gp and CYP2C functional activities, the guinea-pig ABCB1/MDR1 and CYP2C genes were cloned. The recombinant plasmids were then transfected in HEK293 (human embryonic kidney) cells and either calcein-acetoxymethyl ester (AM) accumulation assays or 14,15-EET/DHET formation experiments were performed to evaluate either P-gp transport activity or CYP2C epoxygenase activity, respectively. The guinea-pig tissue distribution of P-gp was studied by Western blotting. Functional expression of CYP2C was demonstrated in guinea-pig liver microsomal preparations. CYP2C-mediated biotransformation of diclofenac and tolbutamide were shown. Expression of P-gp protein was detected in guinea-pig liver and small intestine. Functional activity of guinea-pig P-gp was demonstrated in ABCB1/MDR1-transfected cells. GP-CYP2C-transfected cells also showed functional epoxygenase activity. The guinea-pig expresses functional CYP2C and P-gp, thus suggesting its usefulness for further validating data obtained with other animal models in drug biotransformation/transport studies. Copyright © 2015 John Wiley & Sons, Ltd.

Dose of Phenobarbital and Age of Treatment at Early Life are Two Key Factors for the Persistent Induction of Cytochrome P450 Enzymes in Adult Mouse Liver.

PubMed

Tien, Yun-Chen; Liu, Ke; Pope, Chad; Wang, Pengcheng; Ma, Xiaochao; Zhong, Xiao-bo

2015-12-01

Drug treatment of neonates and infants and its long-term consequences on drug responses have emerged in recent years as a major challenge for health care professionals. In the current study, we use phenobarbital as a model drug and mouse as an in vivo model to demonstrate that the dose of phenobarbital and age of treatment are two key factors for the persistent induction of gene expression and consequential increases of enzyme activities of Cyp2b, Cyp2c, and Cyp3a in adult livers. We show that phenobarbital treatment at early life of day 5 after birth with a low dose (<100 mg/kg) does not change expression and enzyme activities of Cyp2b, Cyp2c, and Cyp3a in adult mouse liver, whereas phenobarbital treatment with a high dose (>200 mg/kg) significantly increases expression and enzyme activities of these P450s in adult liver. We also demonstrate that phenobarbital treatment before day 10 after birth, but not at later ages, significantly increases mRNAs, proteins, and enzyme activities of the tested P450s. Such persistent induction of P450 gene expression and enzyme activities in adult livers by phenobarbital treatment only occurs within a sensitive age window early in life. The persistent induction in gene expression and enzyme activities is higher in female mice than in male mice for Cyp2b10 but not for Cyp2c29 and Cyp3a11. These results will stimulate studies to evaluate the long-term impacts of drug treatment with different doses at neonatal and infant ages on drug metabolism, therapeutic efficacy, and drug-induced toxicity throughout the rest of life. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Impact of visceral leishmaniasis and curative chemotherapy on cytochrome P450 activity in Brazilian patients.

PubMed

Lanchote, Vera Lucia; Almeida, Roque; Barral, Aldina; Barral-Netto, Manoel; Marques, Maria Paula; Moraes, Natália V; da Silva, Angela M; Souza, Tania M V; Suarez-Kurtz, Guilherme

2015-11-01

The aim of the present study was to investigate the impact of human visceral leishmaniasis (VL) and curative chemotherapy on the activity of cytochrome P450 (CYP) 3A, CYP2C9 and CYP2C19 in patients from an endemic region in Brazil. Adult patients with parasitologically confirmed VL were given a CYP phenotyping cocktail, comprising midazolam, omeprazole and losartan, immediately before (Study phase 1), 2-3 days (phase 2) and 3-6 months (phase 3) after curative VL chemotherapy. CYP activity was assessed by the apparent clearance of midazolam (CYP3A), omeprazole/5-hydroxyomeprazol ratio in plasma (CYP2C19) and losartan/E3174 ratio in urine (CYP2C9). Mean values (95% confidence interval) in phases 1, 2 and 3 were, respectively: log apparent midazolam clearance, 1.21 (1.10-1.31), 1.45 (1.32-1.57) and 1.35 (1.26-1.44) ml min(-1)  kg(-1) ; omeprazole/5-hydroxyomeprazole ratio, 0.78 (0.61-0.94), 0.45 (0.27-0.63) and 0.37 (0.20-0.55); losartan/E3174 ratio, 0.66 (0.39-0.92), 0.35 (0.20-0.50) and 0.35 (0.16-0.53). Analysis of variance revealed significant differences in CYP3A (P = 0.018) and CYP2C19 (P = 0.008), but not CYP2C9 (P = 0.11) phenotypic activity, across the three study phases. The phenotypic activities of CYP3A4 and CYP2C19 were significantly reduced during acute VL compared with post-chemotherapy. We propose that increased plasma concentrations of proinflammatory cytokines during active disease account for the suppression of CYP activity. The failure to detect significant changes in CYP2C9 activity in the overall cohort may reflect differential effects of the inflammatory process on the expression of CYP isoforms, although the possibility of insufficient statistical power cannot be dismissed. © 2015 The British Pharmacological Society.

Impact of visceral leishmaniasis and curative chemotherapy on cytochrome P450 activity in Brazilian patients

PubMed Central

Lanchote, Vera Lucia; Almeida, Roque; Barral, Aldina; Barral-Netto, Manoel; Marques, Maria Paula; Moraes, Natália V; da Silva, Angela M; Souza, Tania M V; Suarez-Kurtz, Guilherme

2015-01-01

Aims The aim of the present study was to investigate the impact of human visceral leishmaniasis (VL) and curative chemotherapy on the activity of cytochrome P450 (CYP) 3A, CYP2C9 and CYP2C19 in patients from an endemic region in Brazil. Methods Adult patients with parasitologically confirmed VL were given a CYP phenotyping cocktail, comprising midazolam, omeprazole and losartan, immediately before (Study phase 1), 2–3 days (phase 2) and 3–6 months (phase 3) after curative VL chemotherapy. CYP activity was assessed by the apparent clearance of midazolam (CYP3A), omeprazole/5-hydroxyomeprazol ratio in plasma (CYP2C19) and losartan/E3174 ratio in urine (CYP2C9). Results Mean values (95% confidence interval) in phases 1, 2 and 3 were, respectively: log apparent midazolam clearance, 1.21 (1.10–1.31), 1.45 (1.32–1.57) and 1.35 (1.26–1.44) ml min–1 kg–1; omeprazole/5-hydroxyomeprazole ratio, 0.78 (0.61–0.94), 0.45 (0.27–0.63) and 0.37 (0.20-0.55); losartan/E3174 ratio, 0.66 (0.39–0.92), 0.35 (0.20–0.50) and 0.35 (0.16–0.53). Analysis of variance revealed significant differences in CYP3A (P = 0.018) and CYP2C19 (P = 0.008), but not CYP2C9 (P = 0.11) phenotypic activity, across the three study phases. Conclusion The phenotypic activities of CYP3A4 and CYP2C19 were significantly reduced during acute VL compared with post-chemotherapy. We propose that increased plasma concentrations of proinflammatory cytokines during active disease account for the suppression of CYP activity. The failure to detect significant changes in CYP2C9 activity in the overall cohort may reflect differential effects of the inflammatory process on the expression of CYP isoforms, although the possibility of insufficient statistical power cannot be dismissed. PMID:25940755

The pharmacogenetics and pharmacodynamics of clopidogrel response: an analysis from the PRINC (Plavix Response in Coronary Intervention) trial.

PubMed

Gladding, Patrick; Webster, Mark; Zeng, Irene; Farrell, Helen; Stewart, Jim; Ruygrok, Peter; Ormiston, John; El-Jack, Seif; Armstrong, Guy; Kay, Patrick; Scott, Douglas; Gunes, Arzu; Dahl, Marja-Liisa

2008-12-01

This study assessed the effect of pharmacogenetics on the antiplatelet effect of clopidogrel. Variability in clopidogrel response might be influenced by polymorphisms in genes coding for drug metabolism enzymes (cytochrome P450 [CYP] family), transport proteins (P-glycoprotein) and/or target proteins for the drug (adenosine diphosphate-receptor P2Y12). Sixty patients undergoing elective percutaneous coronary intervention in the randomized PRINC (Plavix Response in Coronary Intervention) trial had platelet function measured using the VerifyNow P2Y12 analyzer after a 600-mg or split 1,200-mg loading dose and after a 75- or 150-mg daily maintenance dosage. Polymerase chain reaction-based genotyping evaluated polymorphisms in the CYP2C19, CYP2C9, CYP3A4, CYP3A5, ABCB1, P2Y12, and CES genes. CYP2C19*1*1 carriers had greater platelet inhibition 2 h after a 600-mg dose (median: 23%, range: 0% to 66%), compared with platelet inhibition in CYP2C19*2 or *4 carriers (10%, 0% to 56%, p = 0.029) and CYP2C19*17 carriers (9%, 0% to 98%, p = 0.026). CYP2C19*2 or *4 carriers had greater platelet inhibition with the higher loading dose than with the lower dose at 4 h (37%, 8% to 87% vs. 14%, 0% to 22%, p = 0.002) and responded better with the higher maintenance dose regimen (51%, 15% to 86% vs. 14%, 0% to 67%, p = 0.042). Carriers of the CYP2C19*2 and *4 alleles showed reduced platelet inhibition after a clopidogrel 600-mg loading dose but responded to higher loading and maintenance dose regimens. Genotyping for the relevant gene polymorphisms may help to individualize and optimize clopidogrel treatment. (Australia New Zealand Clinical Trials Registry; ACTRN12606000129583).

High-Throughput Cytochrome P450 Cocktail Inhibition Assay for Assessing Drug-Drug and Drug-Botanical Interactions

PubMed Central

Li, Guannan; Huang, Ke; Nikolic, Dejan

2015-01-01

Detection of drug-drug interactions is essential during the early stages of drug discovery and development, and the understanding of drug-botanical interactions is important for the safe use of botanical dietary supplements. Among the different forms of drug interactions that are known, inhibition of cytochrome P450 (P450) enzymes is the most common cause of drug-drug or drug-botanical interactions. Therefore, a rapid and comprehensive mass spectrometry–based in vitro high-throughput P450 cocktail inhibition assay was developed that uses 10 substrates simultaneously against nine CYP isoforms. Including probe substrates for CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, and two probes targeting different binding sites of CYP3A4/5, this cocktail simultaneously assesses at least as many P450 enzymes as previous assays while remaining among the fastest due to short incubation times and rapid analysis using ultrahigh pressure liquid chromatography–tandem mass spectrometry. The method was validated using known inhibitors of each P450 enzyme and then shown to be useful not only for single-compound testing but also for the evaluation of potential drug-botanical interactions using the botanical dietary supplement licorice (Glycyrrhiza glabra) as an example. PMID:26285764

The frequency of CYP2C19 genetic polymorphisms in Russian patients with peptic ulcers treated with proton pump inhibitors.

PubMed

Sychev, D A; Denisenko, N P; Sizova, Z M; Grachev, A V; Velikolug, K A

2015-01-01

Proton pump inhibitors, which are widely used as acid-inhibitory agents for the treatment of peptic ulcers, are mainly metabolized by 2C19 isoenzyme of cytochrome P450 (CYP2C19). CYP2C19 has genetic polymorphisms, associated with extensive, poor, intermediate or ultra-rapid metabolism of proton pump inhibitors. Genetic polymorphisms of CYP2C19 could be of clinical concern in the treatment of peptic ulcers with proton pump inhibitors. To investigate the frequencies of CYP2C19*2, CYP2C19*3, and CYP2C19*17 alleles and genotypes in Russian patients with peptic ulcers. We retrospectively reviewed the cases of 971 patients of Caucasian origin with Russian nationality from Moscow region with endoscopically and histologically proven ulcers, 428 males (44%) and 543 females (56%). The mean age was 44.6±11.9 years (range: 15-88 years). DNA was extracted from ethylenediaminetetraacetic acid whole blood samples (10 mL). The polymorphisms CYP2C19 681G.A (CYP2C19*2, rs4244285), CYP2C19 636 G.A (CYP2C19*3, rs4986893) and CYP2C19 -806 C.T (CYP2C19*17, rs12248560) were evaluated using real-time polymerase chain reaction. Regarding CYP2C19 genotype, 317 patients (32.65%) out of 971 were CYP2C19*1/*1 carriers classified as extensive metabolizers. Three hundred and eighty-six (39.75%) with CYP2C19*1/*17 or CYP2C19*17/*17 genotype were ultra-rapid metabolizers. Two hundred and fifty-one people (25.85%) were intermediate metabolizers with CYP2C19*1/*2, CYP2C19*2/*17, CYP2C19*1/*3, CYP2C19*3/*17 genotypes. Seventeen patients (1.75%) with CYP2C19*2/*2, CYP2C19*3/*3, CYP2C19*2/*3 genotypes were poor metabolizers. The allele frequencies were the following: CYP2C19*2 - 0.140, CYP2C19*3 - 0.006, CYP2C19*17 - 0.274. There is a high frequency of CYP2C19 genotypes associated with modified response to proton pump inhibitors in Russian patients with peptic ulcers. Genotyping for CYP2C19 polymorphisms is suggested to be a useful tool for personalized dosing of proton pump inhibitors.

Indole-3-carbinol, but not its major digestive product 3,3'-diindolylmethane, induces reversible hepatocyte hypertrophy and cytochromes P450

DOE Office of Scientific and Technical Information (OSTI.GOV)

Crowell, James A.; Page, John G.; Levine, Barry S.

2006-03-01

Indole-3-carbinol (I-3-C) and 3,3'-diindolylmethane (DIM) have been shown to reduce the incidence and multiplicity of cancers in laboratory animal models. Based on the observation that I-3-C induced hepatocyte hypertrophy when administered orally for 13 weeks to rats, a treatment and recovery study was undertaken to test the hypothesis that the induction of hepatocyte hypertrophy and cytochrome P450 (CYP) activity by I-3-C are adaptive, reversible responses. Additionally, we directly compared the effects of I-3-C to those of its principle metabolite DIM. Rats were treated orally for 28 days with 2 doses of I-3-C (5 and 50 mg I-3-C/kg body weight/day) andmore » DIM (7.5 and 75 mg DIM/kg body weight/day) and then one-half of the animals were not treated for an additional 28 days. Organ weights, histopathology, and the CYP enzyme activities of 1A1/2, 2B1/2, 2C9, 2D6, 2E1, 3A4, and 19 A were measured both after treatment and after recovery. Oral administration of 50 mg I-3-C/kg body weight/day to rats for 28 days significantly increased liver weights and CYP enzyme activities. The effects in males were more pronounced and persistent after recovery than the effects in females. The increased organ weights returned to control values after treatment. Conversely, DIM did not alter liver weights and had no effect on CYP activities after the 28-day treatment. Some changes in CYP activities were measured after the DIM recovery period but the magnitudes of the changes were considered biologically insignificant. The results show that I-3-C, but not DIM, induces reversible adaptive responses in the liver.« less

Altered cytochrome P450 activities and expression levels in the liver and intestines of the monosodium glutamate-induced mouse model of human obesity.

PubMed

Tomankova, Veronika; Liskova, Barbora; Skalova, Lenka; Bartikova, Hana; Bousova, Iva; Jourova, Lenka; Anzenbacher, Pavel; Ulrichova, Jitka; Anzenbacherova, Eva

2015-07-15

Cytochromes P450 (CYPs) are enzymes present from bacteria to man involved in metabolism of endogenous and exogenous compounds incl. drugs. Our objective was to assess whether obesity leads to changes in activities and expression of CYPs in the mouse liver, small intestine and colon. An obese mouse model with repeated injection of monosodium glutamate (MSG) to newborns was used. Controls were treated with saline. All mice were sacrificed at 8 months. In the liver and intestines, levels of CYP mRNA and proteins were analyzed using RT-PCR and Western blotting. Activities of CYP enzymes were measured with specific substrates of human orthologous forms. At the end of the experiment, body weight, plasma insulin and leptin levels as well as the specific content of hepatic CYP enzymes were increased in obese mice. Among CYP enzymes, hepatic CYP2A5 activity, protein and mRNA expression increased most significantly in obese animals. Higher activities and protein levels of hepatic CYP2E1 and 3A in the obese mice were also found. No or a weak effect on CYPs 2C and 2D was observed. In the small intestine and colon, no changes of CYP enzymes were detected except for increased expression of CYP2E1 and decreased expression of CYP3A mRNAs in the colon of the obese mice. Results of our study suggest that the specific content and activities of some liver CYP enzymes (especially CYP2A5) can be increased in obese mice. Higher activity of CYP2A5 (CYP2A6 human ortholog) could lead to altered metabolism of drug substrates of this enzyme (valproic acid, nicotine, methoxyflurane). Copyright © 2015 Elsevier Inc. All rights reserved.

Influence of CYP2C9 polymorphism and phenytoin co-administration on acenocoumarol dose in patients with cerebral venous thrombosis.

PubMed

De, Tanima; Christopher, Rita; Nagaraja, Dindagur

2014-05-01

The study aimed at evaluating the contribution of genetic variations in the drug metabolizing enzyme, CYP2C9, and the influence of co-medication with the antiepileptic drug, phenytoin, to variability in acenocoumarol response, in patients with cerebral venous thrombosis (CVT). 476 acenocoumarol-treated CVT patients (153 males and 323 females) were genotyped for CYP2C9*2 and CYP2C9*3 polymorphisms by PCR-RFLP method. Mean acenocoumarol dose required for achieving and maintaining a stable international normalized ratio (INR) was calculated for different genotypes. The effect of co-administration with phenytoin was determined. Genotype distributions of CYP2C9 were as follows: 83%CYP2C9*1/*1, 8.6%CYP2C9*1/*3, 5.9%CYP2C9*1/*2, 1.9%CYP2C9*3/*3, 0.4%CYP2C9*2/*3 and 0.2%CYP2C9*2/*2. During the initiation phase of anticoagulation the CYP2C9*2 allele was independently associated with low acenocoumarol dose requirement (Adjusted OR 5.38; 95%CI 1.65-17.49; p=0.005). Similarly, the adjusted odds ratio for requiring a low dose during the induction phase in patients bearing the CYP2C9*3 allele was 12.79 (95%CI 4.74-34.57; p<0.0001). During the maintenance phase, CYP2C9*2 and CYP2C9*3 alleles were associated with 19-fold (Adjusted OR 19.67; 95%CI 2.46-157.19; p=0.005) and 11.9-fold odds (Adjusted OR 11.98; 95%CI 2.61-55.08; p=0.001) of requiring a low dose. Clinical covariates such as age, alcohol consumption, postpartum state and oral contraceptive intake also influenced acenocoumarol dosage. Co-medication with phenytoin was associated with lower dose requirement across genotypes during the initiation phase. However, during the maintenance phase, phenytoin-treated patients of all genotypes required higher doses of acenocoumarol. This study emphasizes the fact that polymorphisms in CYP2C9 gene and co-medication with phenytoin alter the anticoagulant effect of acenocoumarol. Copyright © 2014 Elsevier Ltd. All rights reserved.

Absolute protein quantification of clinically relevant cytochrome P450 enzymes and UDP-glucuronosyltransferases by mass spectrometry-based targeted proteomics.

PubMed

Gröer, C; Busch, D; Patrzyk, M; Beyer, K; Busemann, A; Heidecke, C D; Drozdzik, M; Siegmund, W; Oswald, S

2014-11-01

Cytochrome P450 (CYP) enzymes and UDP-glucuronosyltransferases (UGT) are major determinants in the pharmacokinetics of most drugs on the market. To investigate their impact on intestinal and hepatic drug metabolism, we developed and validated quantification methods for nine CYP (CYP1A2, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1, CYP3A4 and CYP3A5) and four UGT enzymes (UGT1A1, UGT1A3, UGT2B7 and UGT2B15) that have been shown to be of clinical relevance in human drug metabolism. Protein quantification was performed by targeted proteomics using liquid chromatography with tandem mass spectrometry (LC-MS/MS)-based determination of enzyme specific peptides after tryptic digestion using in each case stable isotope labelled peptides as internal standard. The chromatography of the respective peptides was performed with gradient elution using a reversed phase (C18) column (Ascentis(®) Express Peptide ES-C18, 100mm×2.1mm, 2.7μm) and 0.1% formic acid (FA) as well as acetonitrile with 0.1% FA as mobile phases at a flow rate of 300μl/min. The MS/MS detection of all peptides was done simultaneously with a scheduled multiple reaction monitoring (MRM) method in the positive mode by monitoring in each case three mass transitions per proteospecific peptide and the internal standard. The assays were validated according to current bioanalytical guidelines with respect to specificity, linearity (0.25-50nM), within-day and between-day accuracy and precision, digestion efficiency as well as stability. Finally, the developed method was successfully applied to determine the CYP and UGT protein amount in human liver and intestinal microsomes. The method was shown to possess sufficient specificity, sensitivity, accuracy, precision and stability to quantify clinically relevant human CYP and UGT enzymes. Copyright © 2014 Elsevier B.V. All rights reserved.

Effect of omeprazole on the pharmacokinetics of moclobemide according to the genetic polymorphism of CYP2C19.

PubMed

Yu, K S; Yim, D S; Cho, J Y; Park, S S; Park, J Y; Lee, K H; Jang, I J; Yi, S Y; Bae, K S; Shin, S G

2001-04-01

Moclobemide, an antidepressant with selective monoamine oxidase-A inhibitory action, is known to be metabolized by CYP2C19 and is also reported to be an inhibitor of CYP2C19, CYP2D6, and CYP1A2. To confirm the involvement of CYP2C19, we performed a pharmacokinetic interaction study. The effect of omeprazole on the pharmacokinetics of moclobemide was studied in 16 healthy volunteers. The volunteer group comprised 8 extensive metabolizers and 8 poor metabolizers of CYP2C19, which was confirmed by genotyping. Subjects were randomly allocated into two sequence groups, and a single-blind, placebo-controlled, two-period crossover study was performed. In study I, a placebo was orally administered for 7 days. On the eighth morning, 300 mg of moclobemide and 40 mg of placebo were coadministered with 200 mL of water, and a pharmacokinetic study was performed. During study II, 40 mg of omeprazole was given each morning instead of placebo, and pharmacokinetic studies were performed on the first and eighth day with 300 mg of moclobemide coadministration. The inhibition of moclobemide metabolism was significant in extensive metabolizers even after a single dose of omeprazole. After daily administration of omeprazole for 1 week, the pharmacokinetic parameters of moclobemide and its metabolites in extensive metabolizers changed to values similar to those in poor metabolizers. In poor metabolizers, no remarkable changes in the pharmacokinetic parameters were observed. Our results show that CYP2C19 is an important enzyme in the elimination of moclobemide and that it is extensively inhibited by omeprazole in extensive metabolizers, but not in poor metabolizers.

Human Hepatic Cytochrome P450-Specific Metabolism of the Organophosphorus Pesticides Methyl Parathion and Diazinon

PubMed Central

Tian, Yuan; Knaak, James B.; Kostyniak, Paul J.; Olson, James R.

2012-01-01

Organophosphorus pesticides (OPs) are a public health concern due to their worldwide use and documented human exposures. Phosphorothioate OPs are metabolized by cytochrome P450s (P450s) through either a dearylation reaction to form an inactive metabolite, or through a desulfuration reaction to form an active oxon metabolite, which is a potent cholinesterase inhibitor. This study investigated the rate of desulfuration (activation) and dearylation (detoxification) of methyl parathion and diazinon in human liver microsomes. In addition, recombinant human P450s were used to determine the P450-specific kinetic parameters (Km and Vmax) for each compound for future use in refining human physiologically based pharmacokinetic/pharmacodynamic (PBPK/PD) models of OP exposure. The primary enzymes involved in bioactivation of methyl parathion were CYP2B6 (Km = 1.25 μM; Vmax = 9.78 nmol · min−1 · nmol P450−1), CYP2C19 (Km = 1.03 μM; Vmax = 4.67 nmol · min−1 · nmol P450−1), and CYP1A2 (Km = 1.96 μM; Vmax = 5.14 nmol · min−1 · nmol P450−1), and the bioactivation of diazinon was mediated primarily by CYP1A1 (Km = 3.05 μM; Vmax = 2.35 nmol · min−1 · nmol P450−1), CYP2C19 (Km = 7.74 μM; Vmax = 4.14 nmol · min−1 · nmol P450−1), and CYP2B6 (Km = 14.83 μM; Vmax = 5.44 nmol · min−1 · nmol P450−1). P450-mediated detoxification of methyl parathion only occurred to a limited extent with CYP1A2 (Km = 16.8 μM; Vmax = 1.38 nmol · min−1 · nmol P450−1) and 3A4 (Km = 104 μM; Vmax = 5.15 nmol · min−1 · nmol P450−1), whereas the major enzyme involved in diazinon detoxification was CYP2C19 (Km = 5.04 μM; Vmax = 5.58 nmol · min−1 · nmol P450−1). The OP- and P450-specific kinetic values will be helpful for future use in refining human PBPK/PD models of OP exposure. PMID:21969518

Therapeutic protein-drug interaction assessment for daclizumab high-yield process in patients with multiple sclerosis using a cocktail approach.

PubMed

Tran, Jonathan Q; Othman, Ahmed A; Wolstencroft, Paul; Elkins, Jacob

2016-07-01

To characterize the potential effect of daclizumab high-yield process (DAC HYP), a monoclonal antibody that blocks the high-affinity interleukin-2 receptors for treatment of multiple sclerosis, on activity of cytochrome P450 (CYP) enzymes. Twenty patients with multiple sclerosis received an oral cocktail of probe substrates of CYP1A2 (caffeine 200 mg), CYP2C9 (warfarin 10 mg/vitamin K 10 mg), CYP2C19 (omeprazole 40 mg), CYP2D6 (dextromethorphan 30 mg) and CYP3A (midazolam 5 mg) on two sequential occasions: 7 days before and 7 days after subcutaneous administration of DAC HYP 150 mg every 4 weeks for three doses. Serial pharmacokinetic blood samples up to 96 h post dose and 12-h urine samples were collected on both occasions. Area under the curve (AUC) for caffeine, S-warfarin, omeprazole and midazolam, and urine dextromethorphan to dextrorphan ratio were calculated. Statistical analyses were conducted on log-transformed parameters using a linear mixed-effects model. The 90% confidence intervals (CIs) for the geometric mean ratio (probe substrate with DAC HYP/probe substrate alone) for caffeine AUC from 0-12 h (0.93-1.15), S-warfarin AUC from 0 to infinity (AUC[0-inf]) (0.95-1.06), omeprazole AUC(0-inf) (0.88-1.13) and midazolam AUC(0-inf) (0.89-1.15) were within the no-effect boundary of 0.80-1.25. The geometric mean ratio for urine dextromethorphan to dextrorphan ratio was 1.01, with the 90% CI (0.76-1.34) extending slightly outside the no-effect boundary, likely due to high variability with urine collections and CYP2D6 activity. DAC HYP treatment in patients with multiple sclerosis had no effect on CYP 1A2, 2C9, 2C19, 2D6 and 3A activity. © 2016 The British Pharmacological Society.

The Cytochrome P450 Enzyme Responsible for the Production of (Z)-Norendoxifen in vitro.

PubMed

Ma, Jianli; Chu, Zhong; Lu, Jessica Bo Li; Liu, Jinzhong; Zhang, Qingyuan; Liu, Zhaoliang; Tang, Dabei

2018-01-01

Norendoxifen, an active metabolite of tamoxifen, is a potent aromatase inhibitor. Little information is available regarding production of norendoxifen in vitro. Here, we conducted a series of kinetic and inhibition studies in human liver microsomes (HLMs) and expressed P450s to study the metabolic disposition of norendoxifen. To validate that norendoxifen was the metabolite of endoxifen, metabolites in HLMs incubates of endoxifen were measured using a HPLC/MS/MS method. To further probe the specific isoforms involved in the metabolic route, endoxifen was incubated with recombinant P450s (CYP 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 3A4, 3A5 and CYP4A11). Formation rates of norendoxifen were evaluated in the absence and presence of P450 isoform specific inhibitors using HLMs. The peak of norendoxifen was found in the incubations consisting of endoxifen, HLMs, and cofactors. The retention times of norendoxifen, endoxifen, and the internal standard (diphenhydramine) were 7.81, 7.97, and 5.86 min, respectively. The K m (app) and V max (app) values of norendoxifen formation from endoxifen in HLM was 47.8 μm and 35.39 pmol min -1 mg -1 . The apparent hepatic intrinsic clearances of norendoxifen formation were 0.74 μl mg -1 min. CYP3A5 and CYP2D6 were the major enzymes capable of norendoxifen formation from endoxifen with the rates of 0.26 and 0.86 pmol pmol -1 P450 × min. CYP1A2, 3A2, 2C9, and 2C19 also contributed to norendoxifen formation, but the contributions were at least 6-fold lower. One micromolar ketoconazole (CYP3A inhibitor) showed an inhibitory effect on the rates of norendoxifen formation by 45%, but 1 μm quinidine (CYP2D6 inhibitor) does not show any inhibitory effect. Norendoxifen, metabolism from endoxifen by multiple P450s that including CYP3A5. © 2018 Wiley-VHCA AG, Zurich, Switzerland.

Transcript levels of genes implicated in steroidogenesis in the testes and fat tissue in relation to androstenone accumulation in fat of pubertal pigs.

PubMed

Robic, A; Feve, K; Riquet, J; Prunier, A

2016-10-01

The present study was performed to measure messenger RNA levels of steroidogenic enzymes in testes and fat tissue and determine whether they are related to fat androstenone level. Real-time polymerase chain reaction experiments were performed on 26 testes and 12 adipose tissue samples from pubertal boars using 21 genes. The absence of significant correlations between fat androstenone and the transcriptional activity of the SRD5A2 and SRD5A3 genes but the high correlation coefficient with that of the SRD5A1 gene (r = 0.62, P < 0.05) suggests that the enzyme coded by SRD5A1 is mainly responsible for the last step of androstenone synthesis. The testicular transcriptional activities of CYP17, CYP11A1, CYP19A, AKR1C-pig6, SRD5A1, LHCGR, and AR were significantly correlated. Only transcriptional levels of CYP17, CYP11A1, CYP19A, SRD5A1, and AKR1C-pig6 were correlated with the fat concentration of androstenone (0.57 < r < 0.70, P < 0.05) confirming that the amount of androstenone stored in fat is related to the production in testes of androstenone and more generally to all sex steroids. Altogether, our data are in favor of a preponderant role of AKR1C-pig6 instead of HSD17B3 for testicular synthesis of steroids. Concerning fat tissue, our data do not support a significant de novo biosynthesis of steroids in porcine adipose tissues. The presence of transcripts coding for steroid enzymes, especially those of AKR1C-pig6, suggests that steroids can be transformed. None of transcript abundance was related to androstenone accumulation (P > 0.1). Therefore, steroids synthesized elsewhere can be transformed in fat tissue but synthesis of androstenone is unlikely. Copyright © 2016 Elsevier Inc. All rights reserved.

In vitro characterization of sarizotan metabolism: hepatic clearance, identification and characterization of metabolites, drug-metabolizing enzyme identification, and evaluation of cytochrome p450 inhibition.

PubMed

Gallemann, Dieter; Wimmer, Elmar; Höfer, Constance C; Freisleben, Achim; Fluck, Markus; Ladstetter, Bernhard; Dolgos, Hugues

2010-06-01

In vitro biotransformation studies of sarizotan using human liver microsomes (HLM) showed aromatic and aliphatic monohydroxylation and dealkylation. Recombinant cytochromes P450 (P450) together with P450-selective inhibitors in HLM/hepatocyte cultures were used to evaluate the relative contribution of different P450s and revealed major involvement of CYP3A4, CYP2C9, CYP2C8, and CYP1A2 in sarizotan metabolism. The apparent K(m, u) and V(max) of sarizotan clearance, as investigated in HLM, were 9 microM and 3280 pmol/mg/min, predicting in vivo hepatic clearance of 0.94 l/h, which indicates that sarizotan is a low-clearance compound in humans and suggests nonsaturable metabolism at the targeted plasma concentration (< or =1 microM). This finding is confirmed by the reported human clearance (CL/F of 3.6-4.4 l/h) and by the dose-linear area under the curve increase observed with doses up to 25 mg. The inhibitory effect of sarizotan toward six major P450s was evaluated using P450-specific marker reactions in pooled HLM. K(i, u) values of sarizotan against CYP2C8, CYP2C19, and CYP3A4 were >10 microM, whereas those against CYP2D6 and CYP1A2 were 0.43 and 8.7 microM, respectively. Based on the estimates of sarizotan concentrations at the enzyme active sites, no clinically significant drug-drug interactions (DDIs) due to P450 inhibition are expected. This result has been confirmed in human DDI studies in which no inhibition of five major P450s was observed in terms of marker metabolite formation.

Pharmacogenetic testing for clopidogrel using the rapid INFINITI analyzer: a dose-escalation study.

PubMed

Gladding, Patrick; White, Harvey; Voss, Jamie; Ormiston, John; Stewart, Jim; Ruygrok, Peter; Bvaldivia, Badi; Baak, Ruth; White, Catherine; Webster, Mark

2009-11-01

Our aim was to assess whether a higher clopidogrel maintenance dose has a greater antiplatelet effect in CYP2C19*2 allele carriers compared with noncarriers. Clopidogrel is a prodrug that is biotransformed by the cytochrome P450 enzymes CYP2C19, 2C9, and 3A4, 2B6, 1A2. The CYPC219*2 loss of function variant has been associated with a reduced antiplatelet response to clopidogrel and a 3-fold risk of stent thrombosis. Forty patients on standard maintenance dosage clopidogrel (75 mg), for 9.4 +/- 9.2 weeks, were enrolled into a dose escalation study. Platelet function was assessed at baseline and after 1 week of 150 mg once daily using the VerifyNow platelet function analyzer (Accumetrics Ltd., San Diego, California). Genomic DNA was hybridized to a BioFilmChip microarray on the INFINITI analyzer (AutoGenomics Inc., Carlsbad, California) and analyzed for the CYP19*2, *4, *17, and CYP2C9*2, *3 polymorphisms. Platelet inhibition increased over 1 week, mean +8.6 +/- 13.5% (p = 0.0003). Carriers of the CYP2C19*2 allele had significantly reduced platelet inhibition at baseline (median 18%, range 0% to 72%) compared with wildtype (wt) (median 59%, range 11% to 95%, p = 0.01) and at 1 week (p = 0.03). CYP2C19*2 allele carriers had an increase in platelet inhibition of (mean +9 +/- 11%, p = 0.03) and reduction in platelet reactivity (mean -26 +/- 38 platelet response unit, p = 0.04) with a higher dose. Together CYP2C19*2 and CYP2C9*3 loss of function carriers had a greater change in platelet inhibition with 150 mg daily than wt/wt (+10.9% vs. +0.7%, p = 0.04). Increasing the dose of clopidogrel in patients with nonresponder polymorphisms can increase antiplatelet response. Personalizing clopidogrel dosing using pharmacogenomics may be an effective method of optimizing treatment.

The pharmacokinetic and pharmacodynamic interaction of clopidogrel and cilostazol in relation to CYP2C19 and CYP3A5 genotypes

PubMed Central

Kim, Ho‐Sook; Lim, Younghae; Oh, Minkyung; Ghim, Jong‐lyul; Kim, Eun‐Young; Kim, Dong‐Hyun

2015-01-01

Aim The primary objective of the present study was to evaluate the pharmacokinetic and pharmacodynamic interactions between clopidogrel and cilostazol in relation to the CYP2C19 and CYP3A5 genotypes. Methods In a randomized, three‐way crossover study, 27 healthy subjects were administered clopidogrel (300 mg), cilostazol (100 mg) or clopidogrel + cilostazol orally. Plasma concentrations of clopidogrel, cilostazol and their active metabolites (clopidogrel thiol metabolite, 3,4‐dehydrocilostazol and 4″‐trans‐hydroxycilostazol), and adenosine diphosphate‐induced platelet aggregation were measured for pharmacokinetic and pharmacodynamic assessment. Results The area under the plasma concentration–time curve (AUC) of the active thiol metabolite of clopidogrel was highest in the CYP2C19 extensive metabolizers (EM) and lowest in the poor metabolizers (PM). Cilostazol decreased the thiol metabolite AUC by 29% in the CYP3A5*1/*3 genotype [geometric mean ratio (GMR) 0.71; 90% confidence interval (CI) 0.58, 0.86; P = 0.020] but not in the CYP3A5*3/*3 genotype (GMR 0.93; 90% CI 0.80, 1.10; P = 0.446). Known effects of the CYP2C19 and CYP3A5 genotypes on the exposure of cilostazol and its metabolites were observed but there was no significant difference in the AUC of cilostazol and 3,4‐dehydrocilostazol between cilostazol and clopidogrel + cilostazol. The inhibition of platelet aggregation from 4 h to 24 h (IPA4–24) following the administration of clopidogrel alone was highest in the CYP2C19 EM genotype and lowest in the CYP2C19 PM genotype (59.05 ± 18.95 vs. 36.74 ± 13.26, P = 0.023). However, the IPA of the CYP2C19 PM following co‐administration of clopidogrel and cilostazol was comparable with that of the CYP2C19 EM and intermediate metabolizers (IM) only in CYP3A5*3/*3 subjects. Conclusions The additive antiplatelet effect of cilostazol plus clopidogrel is maximized in subjects with both the CYP2C19 PM and CYP3A5*3/*3 genotypes because of a lack of change of clopidogrel thiol metabolite exposure in CYP3A5*3/*3 as well as the highest cilostazol IPA in CYP2C19 PM and CYP3A5*3/*3 subjects. PMID:26426352

Inhibition of mitogen-activated protein kinase kinase, DNA methyltransferase, and transforming growth factor-β promotes differentiation of human induced pluripotent stem cells into enterocytes.

PubMed

Kodama, Nao; Iwao, Takahiro; Kabeya, Tomoki; Horikawa, Takashi; Niwa, Takuro; Kondo, Yuki; Nakamura, Katsunori; Matsunaga, Tamihide

2016-06-01

We previously reported that small-molecule compounds were effective in generating pharmacokinetically functional enterocytes from human induced pluripotent stem (iPS) cells. In this study, to determine whether the compounds promote the differentiation of human iPS cells into enterocytes, we investigated the effects of a combination of mitogen-activated protein kinase kinase (MEK), DNA methyltransferase (DNMT), and transforming growth factor (TGF)-β inhibitors on intestinal differentiation. Human iPS cells cultured on feeder cells were differentiated into endodermal cells by activin A. These endodermal-like cells were then differentiated into intestinal stem cells by fibroblast growth factor 2. Finally, the cells were differentiated into enterocyte cells by epidermal growth factor and small-molecule compounds. After differentiation, mRNA expression levels and drug-metabolizing enzyme activities were measured. The mRNA expression levels of the enterocyte marker sucrase-isomaltase and the major drug-metabolizing enzyme cytochrome P450 (CYP) 3A4 were increased by a combination of MEK, DNMT, and TGF-β inhibitors. The mRNA expression of CYP3A4 was markedly induced by 1α,25-dihydroxyvitamin D3. Metabolic activities of CYP1A1/2, CYP2B6, CYP2C9, CYP2C19, CYP3A4/5, UDP-glucuronosyltransferase, and sulfotransferase were also observed in the differentiated cells. In conclusion, MEK, DNMT, and TGF-β inhibitors can be used to promote the differentiation of human iPS cells into pharmacokinetically functional enterocytes. Copyright © 2016 The Japanese Society for the Study of Xenobiotics. Published by Elsevier Ltd. All rights reserved.

Pharmacogenomics of CYP2C9: Functional and Clinical Considerations†

PubMed Central

Rettie, Allan E.; Fowler, Douglas M.; Miners, John O.

2017-01-01

CYP2C9 is the most abundant CYP2C subfamily enzyme in human liver and the most important contributor from this subfamily to drug metabolism. Polymorphisms resulting in decreased enzyme activity are common in the CYP2C9 gene and this, combined with narrow therapeutic indices for several key drug substrates, results in some important issues relating to drug safety and efficacy. CYP2C9 substrate selectivity is detailed and, based on crystal structures for the enzyme, we describe how CYP2C9 catalyzes these reactions. Factors relevant to clinical response to CYP2C9 substrates including inhibition, induction and genetic polymorphism are discussed in detail. In particular, we consider the issue of ethnic variation in pattern and frequency of genetic polymorphisms and clinical implications. Warfarin is the most well studied CYP2C9 substrate; recent work on use of dosing algorithms that include CYP2C9 genotype to improve patient safety during initiation of warfarin dosing are reviewed and prospects for their clinical implementation considered. Finally, we discuss a novel approach to cataloging the functional capabilities of rare ‘variants of uncertain significance’, which are increasingly detected as more exome and genome sequencing of diverse populations is conducted. PMID:29283396

Preliminary Investigation of the Contribution of CYP2A6, CYP2B6, and UGT1A9 Polymorphisms on Artesunate-Mefloquine Treatment Response in Burmese Patients with Plasmodium falciparum Malaria

PubMed Central

Phompradit, Papichaya; Muhamad, Poonuch; Cheoymang, Anurak; Na-Bangchang, Kesara

2014-01-01

CYP2A6, CYP2B6, and UGT1A9 genetic polymorphisms and treatment response after a three-day course of artesunate-mefloquine was investigated in 71 Burmese patients with uncomplicated Plasmodium falciparum malaria. Results provide evidence for the possible link between CYP2A6 and CYP2B6 polymorphisms and plasma concentrations of artesunate/dihydroartemisinin and treatment response. In one patient who had the CYP2A6*1A/*4C genotype (decreased enzyme activity), plasma concentration of artesunate at one hour appeared to be higher, and the concentration of dihydroartemisinin was lower than for those carrying other genotypes (415 versus 320 ng/mL). The proportion of patients with adequate clinical and parasitologic response who had the CYP2B6*9/*9 genotype (mutant genotype) was significantly lower compared with those with late parasitologic failure (14.0% versus 19.0%). Confirmation through a larger study in various malaria-endemic areas is required before a definite conclusion on the role of genetic polymorphisms of these drug-metabolizing enzymes on treatment response after artesunate-based combination therapy can be made. PMID:24891466

Cytochrome P-450 isoforms involved in carboxylic acid ester cleavage of Hantzsch pyridine ester of pranidipine.

PubMed

Kudo, S; Okumura, H; Miyamoto, G; Ishizaki, T

1999-02-01

Cytochrome P-450 (CYP) isoforms responsible for the cleavage of Hantzsch pyridine ester at the 3-position of pranidipine were studied in vitro using cDNA-expressed human CYP enzymes. CYP1A1, 1A2, 2D6, and 3A4 cleaved the ester with a catalytic activity of 5.5, 0. 93, 13.1, and 22.4 nmol/30 min/nmol P-450, respectively. CYP2A6, 2B6, 2C8, 2C9, 2C19, and 2E1 were not involved in the de-esterification. The Km and Vmax values for the de-esterification were 11.8 microM and 0.47 nmol/min/nmol P-450 in the CYP2D6-catalyzed reaction and 8. 7 microM and 0.84 nmol/min/nmol P-450 in the CYP3A4-catalyzed reaction. The intrinsic clearance (Vmax/Km) of the de-esterification by CYP3A4 was 2-fold greater than that by CYP2D6. Quinidine almost completely inhibited the CYP2D6-mediated de-esterification at the concentration of 1 x 10(-6) M. Ketoconazole and troleandomycin inhibited the CYP3A4-mediated reaction in a dose-related manner. The results indicate that although the multiple CYP isoforms can catalyze the de-esterification, CYP3A4 and 2D6 are the major isoforms.

The wild Egyptian artichoke as a promising functional food for the treatment of hepatitis C virus as revealed via UPLC-MS and clinical trials.

PubMed

Elsebai, Mahmoud Fahmi; Abass, Khaled; Hakkola, Jukka; Atawia, Ahmed Rezk; Farag, Mohamed A

2016-07-13

Infection by hepatitis C virus (HCV) and its subsequent complications are a major cause of mortality worldwide. The water extract of the wild Egyptian artichoke (WEA) (Cynara cardunculus L. var. sylvestris (Lam.) Fiori) leaves is a freely available herbal product that is used for treatment of HCV-infection complications such as jaundice and ascites. The purpose of this study was to evaluate whether WEA exhibits activity against HCV, identify bioactive chemicals in its extract and to tentatively examine the potential inhibitory interactions of WEA with human drug-metabolizing enzymes. The current pilot clinical trial revealed that the water extract of a WEA plant decreased the HCV viral load below the detection level in 12 out of 15 patients. Furthermore, the liver enzymes ALT and AST, as well as the level of bilirubin were normalized. The total WEA extract inhibited CYP2B6 (OH-BUP) and CYP2C19 (5-OH-OME) with high affinity, IC50 ∼ 20 μg ml(-1), while moderate inhibitory interactions were observed for CYP1A2, CYP2D6, CYP2E1 and CYP3A4. Results presented herein suggest that the WEA exhibits strong antiviral activity against HCV and may be useful for its treatment. Compared to the artichoke product "Hepar SL Forte(®)", WEA was found to be more enriched in sesquiterpenes versus the abundance of phenolic compounds, especially flavonoids in Hepar SL Forte(®) as revealed via UPLC-MS analysis coupled to chemometrics.

Neurological toxicity after phenytoin infusion in a pediatric patient with epilepsy: influence of CYP2C9, CYP2C19 and ABCB1 genetic polymorphisms.

PubMed

Dorado, P; López-Torres, E; Peñas-Lledó, E M; Martínez-Antón, J; Llerena, A

2013-08-01

Pharmacogenetic studies have shown that genetic defects in drug-metabolizing enzymes encoded by CYP2C9, CYP2C19 genes and by the transporter ABCB1 gene can influence phenytoin (PTH) plasma levels and toxicity. The patient reported here is a 2-year-old girl with a medical history of cryptogenic (probably symptomatic) epilepsy, who had her first focal seizure with secondary generalization at 13 months of age. She initially received oral valproate treatment and three months later, she was prescribed an oral oxcarbazepine treatment. At 20 months of age, she was admitted to the Emergency Department because of generalized convulsive Status Epilepticus needing to be immediately treated with rectal diazepam (0.5 mg kg(-1)), intravenous diazepam (0.3 mg kg(-1)), and intravenous phenytoin with an initial-loading dose of 15 mg kg(-1). However, two hours after the initial-loading dose of PTH, the patient developed dizziness, nystagmus, ataxia and excessive sedation. Other potential causes of PTH toxicity were excluded such as drug interactions, decreased albumin or lab error. Therefore, to explain the neurological toxicity, PTH plasma levels and CYP2C9, CYP2C19 and ABCB1 genetic polymorphisms were analyzed. Initial plasma PTH levels were higher than expected (69 mg l(-1); normal range: 10-20 mg l(-1)), and the patient was homozygous for the CYP2C9*2 allele, heterozygous for the CYP2C19*4 allele and homozygous for the 3435C and 1236C ABCB1 alleles. Present findings support the previously established relationship between CYP2C9 and CYP2C19 genetic polymorphisms and the increased risk to develop PTH toxicity owing to high plasma concentrations. Nevertheless, although the association of these genes with PTH-induced adverse effects has been well-documented in adult populations, this is the first report examining the influence of these genetic polymorphisms on PTH plasma levels and toxicity in a pediatric patient.

Inhibitors of steroidal cytochrome p450 enzymes as targets for drug development.

PubMed

Baston, Eckhard; Leroux, Frédéric R

2007-01-01

Cytochrome P450's are enzymes which catalyze a large number of biological reactions, for example hydroxylation, N-, O-, S- dealkylation, epoxidation or desamination. Their substrates include fatty acids, steroids or prostaglandins. In addition, a high number of various xenobiotics are metabolized by these enzymes. The enzyme 17alpha-hydroxylase-C17,20-lyase (P450(17), CYP 17, androgen synthase), a cytochrome P450 monooxygenase, is the key enzyme for androgen biosynthesis. It catalyzes the last step of the androgen biosynthesis in the testes and adrenal glands and produces androstenedione and dehydroepiandrosterone from progesterone and pregnenolone. The microsomal enzyme aromatase (CYP19) transforms these androgens to estrone and estradiol. Estrogens stimulate tumor growth in hormone dependent breast cancer. In addition, about 80 percent of prostate cancers are androgen dependent. Selective inhibitors of these enzymes are thus important alternatives to treatment options like antiandrogens or antiestrogens. The present article deals with recent patents (focus on publications from 2000 - 2006) concerning P450 inhibitor design where steroidal substrates are involved. In this context a special focus is provided for CYP17 and CYP19. Mechanisms of action will also be discussed. Inhibitors of CYP11B2 (aldosterone synthase) will also be dealt with.

Structure-activity relationship (SAR) analysis of a family of steroids acutely controlling steroidogenesis.

PubMed

Midzak, Andrew; Rammouz, Georges; Papadopoulos, Vassilios

2012-11-01

Steroids metabolically derive from lipid cholesterol, and vertebrate steroids additionally derive from the steroid pregnenolone. Pregnenolone is derived from cholesterol by hydrolytic cleavage of the aliphatic tail by mitochondrial cytochrome P450 enzyme CYP11A1, located in the inner mitochondrial membrane. Delivery of cholesterol to CYP11A1 comprises the principal control step of steroidogenesis, and requires a series of proteins spanning the mitochondrial double membranes. A critical member of this cholesterol translocation machinery is the integral outer mitochondrial membrane translocator protein (18kDa, TSPO), a high-affinity drug- and cholesterol-binding protein. The cholesterol-binding site of TSPO consists of a phylogenetically conserved cholesterol recognition/interaction amino acid consensus (CRAC). Previous studies from our group identified 5-androsten-3β,17,19-triol (19-Atriol) as drug ligand for the TSPO CRAC motif inhibiting cholesterol binding to CRAC domain and steroidogenesis. To further understand 19-Atriol's mechanism of action as well as the molecular recognition by the TSPO CRAC motif, we undertook structure-activity relationship (SAR) analysis of the 19-Atriol molecule with a variety of substituted steroids oxygenated at positions around the steroid backbone. We found that in addition to steroids hydroxylated at carbon C19, hydroxylations at C4, C7, and C11 contributed to inhibition of cAMP-mediated steroidogenesis in a minimal steroidogenic cell model. However, only substituted steroids with C19 hydroxylations exhibited specificity to TSPO, its CRAC motif, and mitochondrial cholesterol transport, as the C4, C7, and C11 hydroxylated steroids inhibited the metabolic transformation of cholesterol by CYP11A1. We thus provide new insights into structure-activity relationships of steroids inhibiting mitochondrial cholesterol transport and steroidogenic cholesterol metabolic enzymes. Copyright © 2012 Elsevier Inc. All rights reserved.

Pharmacoepidemiologic and in vitro evaluation of potential drug–drug interactions of sulfonylureas with fibrates and statins

PubMed Central

Schelleman, H; Han, X; Brensinger, C M; Quinney, S K; Bilker, W B; Flockhart, D A; Li, L; Hennessy, Sean

2014-01-01

Aims To examine whether initiation of fibrates or statins in sulfonylurea users is associated with hypoglycaemia, and examine in vitro inhibition of cytochrome P450 (CYP) enzymes by statins, fenofibrate and glipizide. Methods We used healthcare data to conduct nested case-control studies of serious hypoglycaemia (i.e. resulting in hospital admission or emergency department treatment) in persons taking glipizide or glyburide, and calculated adjusted overall and time-stratified odds ratios (ORs) and 95% confidence intervals (CIs). We also characterized the in vitro inhibition of CYP enzymes by statins, fenofibrate and glipizide using fluorometric CYP450 inhibition assays, and estimated area under the concentration–time curve ratios (AUCRs) for the drug pairs. Results We found elevated adjusted overall ORs for glyburide-fenofibrate (OR 1.84, 95% CI 1.37, 2.47) and glyburide-gemfibrozil (OR 1.57, 95% CI 1.25, 1.96). The apparent risk did decline over time as might be expected from a pharmacokinetic mechanism. Fenofibrate was a potent in vitro inhibitor of CYP2C19 (IC50 = 0.2 μm) and CYP2B6 (IC50 = 0.7 μm) and a moderate inhibitor of CYP2C9 (IC50 = 9.7 μm). The predicted CYP-based AUCRs for fenofibrate-glyburide and gemfibrozil-glyburide interactions were only 1.09 and 1.04, suggesting that CYP inhibition is unlikely to explain such an interaction. Conclusions Use of fenofibrate or gemfibrozil together with glyburide was associated with elevated overall risks of serious hypoglycaemia. CYP inhibition seems unlikely to explain this observation. We speculate that a pharmacodynamic effect of fibrates (e.g. activate peroxisome proliferator-activator receptor alpha) may contribute to these apparent interactions. PMID:24548191

Potent inhibition of cytochrome P450 2B6 by sibutramine in human liver microsomes.

PubMed

Bae, Soo Hyeon; Kwon, Min Jo; Choi, Eu Jin; Zheng, Yu Fen; Yoon, Kee Dong; Liu, Kwang-Hyeon; Bae, Soo Kyung

2013-09-05

The present study was performed to evaluate the potency and specificity of sibutramine as an inhibitor of the activities of nine human CYP isoforms in liver microsomes. Using a cocktail assay, the effects of sibutramine on specific marker reactions of the nine CYP isoforms were measured in human liver microsomes. Sibutramine showed potent inhibition of CYP2B6-mediated bupropion 6-hydroxylation with an IC50 value of 1.61μM and Ki value of 0.466μM in a competitive manner at microsomal protein concentrations of 0.25mg/ml; this was 3.49-fold more potent than the typical CYP2B6 inhibitor thio-TEPA (Ki=1.59μM). In addition, sibutramine slightly inhibited CYP2C19 activity (Ki=16.6μM, noncompetitive inhibition) and CYP2D6 activity (Ki=15.7μM, noncompetitive inhibition). These observations indicated 35.6- and 33.7-fold decreases in inhibition potency, respectively, compared with that of CYP2B6 by sibutramine. However, no inhibition of CYP1A2, CYP2A6, CYP2C8, CYP2C9, CYP2D6, or CYP2E1 activities was observed. In addition, the CYP2B6 inhibitory potential of sibutramine was enhanced at a lower microsomal protein concentration of 0.05mg/ml. After 30min preincubation of human liver microsomes with sibutramine in the presence of NADPH, no shift in IC50 was observed in terms of inhibition of the activities of the nine CYPs, suggesting that sibutramine is not a time-dependent inactivator. These observations suggest that sibutramine is a selective and potent inhibitor of CYP2B6 in vitro, whereas inhibition of other CYPs is substantially lower. These in vitro data support the use of sibutramine as a well-known inhibitor of CYP2B6 for routine screening of P450 reversible inhibition when human liver microsomes are used as the enzyme source. Copyright © 2013 Elsevier Ireland Ltd. All rights reserved.

Nuclear Receptors in Drug Metabolism, Drug Response and Drug Interactions

PubMed Central

Prakash, Chandra; Zuniga, Baltazar; Song, Chung Seog; Jiang, Shoulei; Cropper, Jodie; Park, Sulgi; Chatterjee, Bandana

2016-01-01

Orally delivered small-molecule therapeutics are metabolized in the liver and intestine by phase I and phase II drug-metabolizing enzymes (DMEs), and transport proteins coordinate drug influx (phase 0) and drug/drug-metabolite efflux (phase III). Genes involved in drug metabolism and disposition are induced by xenobiotic-activated nuclear receptors (NRs), i.e. PXR (pregnane X receptor) and CAR (constitutive androstane receptor), and by the 1α, 25-dihydroxy vitamin D3-activated vitamin D receptor (VDR), due to transactivation of xenobiotic-response elements (XREs) present in phase 0-III genes. Additional NRs, like HNF4-α, FXR, LXR-α play important roles in drug metabolism in certain settings, such as in relation to cholesterol and bile acid metabolism. The phase I enzymes CYP3A4/A5, CYP2D6, CYP2B6, CYP2C9, CYP2C19, CYP1A2, CYP2C8, CYP2A6, CYP2J2, and CYP2E1 metabolize >90% of all prescription drugs, and phase II conjugation of hydrophilic functional groups (with/without phase I modification) facilitates drug clearance. The conjugation step is mediated by broad-specificity transferases like UGTs, SULTs, GSTs. This review delves into our current understanding of PXR/CAR/VDR-mediated regulation of DME and transporter expression, as well as effects of single nucleotide polymorphism (SNP) and epigenome (specified by promoter methylation, histone modification, microRNAs, long non coding RNAs) on the expression of PXR/CAR/VDR and phase 0-III mediators, and their impacts on variable drug response. Therapeutic agents that target epigenetic regulation and the molecular basis and consequences (overdosing, underdosing, or beneficial outcome) of drug-drug/drug-food/drug-herb interactions are also discussed. Precision medicine requires understanding of a drug’s impact on DME and transporter activity and their NR-regulated expression in order to achieve optimal drug efficacy without adverse drug reactions. In future drug screening, new tools such as humanized mouse models and microfluidic organs-on-chips, which mimic the physiology of a multicellular environment, will likely replace the current cell-based workflow. PMID:27478824

Association of cytochrome P450 genetic polymorphisms with neoadjuvant chemotherapy efficacy in breast cancer patients

PubMed Central

2012-01-01

Background The enzymes of the cytochrome P450 family (CYPs) play an important role in the metabolism of a great variety of anticancer agents; therefore, polymorphisms in genes encoding for metabolizing enzymes and drugs transporters can affect drug efficacy and toxicity. Methods The genetic polymorphisms of cytochrome P450 were studied in 395 patients with breast cancer by RLFP analysis. Results Here, we studied the association of functionally significant variant alleles of CYP3A4, CYP3A5, CYP2B6, CYP2C8, CYP2C9 and CYP2C19 with the clinical response to neoadjuvant chemotherapy in breast cancer patients. A significant correlation was observed between the CYP2C9*2 polymorphism and chemotherapy resistance (OR = 4.64; CI 95% = 1.01 – 20.91), as well as between CYP2C9*2 heterozygotes and chemotherapy resistance in women with nodal forms of breast cancer and a cancer hereditary load (OR = 15.50; CI 95% = 1.08 – 826.12) when the potential combined effects were examined. No significant association between chemotherapy resistance and the other examined genotypes and the potential combined clinical and tumour-related parameters were discovered. Conclusion In conclusion, CYP2C9*2 was associated with neoadjuvant chemotherapy resistance (OR = 4.64; CI 95% = 1.01 – 20.91) in the population of interest. PMID:22702493

Comparison of Liver Cell Models Using the Basel Phenotyping Cocktail.

PubMed

Berger, Benjamin; Donzelli, Massimiliano; Maseneni, Swarna; Boess, Franziska; Roth, Adrian; Krähenbühl, Stephan; Haschke, Manuel

2016-01-01

Currently used hepatocyte cell systems for in vitro assessment of drug metabolism include hepatoma cell lines and primary human hepatocyte (PHH) cultures. We investigated the suitability of the validated in vivo Basel phenotyping cocktail (caffeine [CYP1A2], efavirenz [CYP2B6], losartan [CYP2C9], omeprazole [CYP2C19], metoprolol [CYP2D6], midazolam [CYP3A4]) in vitro and characterized four hepatocyte cell systems (HepG2 cells, HepaRG cells, and primary cryopreserved human hepatocytes in 2-dimensional [2D] culture or in 3D-spheroid co-culture) regarding basal metabolism and CYP inducibility. Under non-induced conditions, all CYP activities could be determined in 3D-PHH, CYP2B6, CYP2C19, CYP2D6, and CYP3A4 in 2D-PHH and HepaRG, and CYP2C19 and CYP3A4 in HepG2 cells. The highest non-induced CYP activities were observed in 3D-PHH and HepaRG cells. mRNA expression was at least four-fold higher for all CYPs in 3D-PHH compared to the other cell systems. After treatment with 20 μM rifampicin, mRNA increased 3- to 50-fold for all CYPs except CYP1A2 and 2D6 for HepaRG and 3D-PHH, 4-fold (CYP2B6) and 17-fold (CYP3A4) for 2D-PHH and four-fold (CYP3A4) for HepG2. In 3D-PHH at least a two-fold increase in CYP activity was observed for all inducible CYP isoforms while CYP1A2 and CYP2C9 activity did not increase in 2D-PHH and HepaRG. CYP inducibility assessed in vivo using the same phenotyping probes was also best reflected by the 3D-PHH model. Our studies show that 3D-PHH and (with some limitations) HepaRG are suitable cell systems for assessing drug metabolism and CYP induction in vitro . HepG2 cells are less suited to assess CYP induction of the 2C and 3A family. The Basel phenotyping cocktail is suitable for the assessment of CYP activity and induction also in vitro .

Comparison of Liver Cell Models Using the Basel Phenotyping Cocktail

PubMed Central

Berger, Benjamin; Donzelli, Massimiliano; Maseneni, Swarna; Boess, Franziska; Roth, Adrian; Krähenbühl, Stephan; Haschke, Manuel

2016-01-01

Currently used hepatocyte cell systems for in vitro assessment of drug metabolism include hepatoma cell lines and primary human hepatocyte (PHH) cultures. We investigated the suitability of the validated in vivo Basel phenotyping cocktail (caffeine [CYP1A2], efavirenz [CYP2B6], losartan [CYP2C9], omeprazole [CYP2C19], metoprolol [CYP2D6], midazolam [CYP3A4]) in vitro and characterized four hepatocyte cell systems (HepG2 cells, HepaRG cells, and primary cryopreserved human hepatocytes in 2-dimensional [2D] culture or in 3D-spheroid co-culture) regarding basal metabolism and CYP inducibility. Under non-induced conditions, all CYP activities could be determined in 3D-PHH, CYP2B6, CYP2C19, CYP2D6, and CYP3A4 in 2D-PHH and HepaRG, and CYP2C19 and CYP3A4 in HepG2 cells. The highest non-induced CYP activities were observed in 3D-PHH and HepaRG cells. mRNA expression was at least four-fold higher for all CYPs in 3D-PHH compared to the other cell systems. After treatment with 20 μM rifampicin, mRNA increased 3- to 50-fold for all CYPs except CYP1A2 and 2D6 for HepaRG and 3D-PHH, 4-fold (CYP2B6) and 17-fold (CYP3A4) for 2D-PHH and four-fold (CYP3A4) for HepG2. In 3D-PHH at least a two-fold increase in CYP activity was observed for all inducible CYP isoforms while CYP1A2 and CYP2C9 activity did not increase in 2D-PHH and HepaRG. CYP inducibility assessed in vivo using the same phenotyping probes was also best reflected by the 3D-PHH model. Our studies show that 3D-PHH and (with some limitations) HepaRG are suitable cell systems for assessing drug metabolism and CYP induction in vitro. HepG2 cells are less suited to assess CYP induction of the 2C and 3A family. The Basel phenotyping cocktail is suitable for the assessment of CYP activity and induction also in vitro. PMID:27917125

Effects of Neonicotinoid Pesticides on Promoter-Specific Aromatase (CYP19) Expression in Hs578t Breast Cancer Cells and the Role of the VEGF Pathway.

PubMed

Caron-Beaudoin, Élyse; Viau, Rachel; Sanderson, J Thomas

2018-04-26

Aromatase (CYP19) is a key enzyme in estrogens biosynthesis. In the mammary gland, CYP19 gene is expressed at low levels under the regulation of its I.4 promoter. In hormone-dependent breast cancer, fibroblast cells surrounding the tumor express increased levels of CYP19 mRNA due to a decrease of I.4 promoter activity and an increase of PII, I.3, and I.7 promoter activity. Little is known about the effects of environmental chemicals on the promoter-specific CYP19 expression. We aimed to determine the effects of two neonicotinoids (thiacloprid and imidacloprid) on promoter-specific CYP19 expression in Hs578t breast cancer cells and understand the signaling pathways involved. Hs578t cells were exposed to various signaling pathway stimulants or neonicotinoids for 24 h. Promoter-specific expression of CYP19 was determined by real-time quantitative polymerase chain reaction and catalytic activity of aromatase by tritiated water release assay. To our knowledge, we are the first to demonstrate that the normal I.4 promoter and the breast cancer-relevant PII, I.3, and I.7 promoters of CYP19 are active in these cells. We found that the expression of CYP19 via promoters PII, I.3, and I.7 in Hs578t cells was, in part, dependent on the activation of two VEGF signaling pathways: mitogen-activated protein kinase (MAPK) 1/3 and phospholipase C (PLC). Exposure of Hs578t cells to environmental concentrations of imidacloprid and thiacloprid resulted in a switch in CYP19 promoter usage, involving inhibition of I.4 promoter activity and an increase of PII, I.3, and I.7 promoter-mediated CYP19 expression and aromatase catalytic activity. Greater effects were seen at lower concentrations. Our results suggest that thiacloprid and imidacloprid exert their effects at least partially by inducing the MAPK 1/3 and/or PLC pathways. We demonstrated in vitro that neonicotinoids may stimulate a change in CYP19 promoter usage similar to that observed in patients with hormone-dependent breast cancer. https://doi.org/10.1289/EHP2698.

The roles of carboxylesterase and CYP isozymes on the in vitro metabolism of T-2 toxin.

PubMed

Lin, Ni-Ni; Chen, Jia; Xu, Bin; Wei, Xia; Guo, Lei; Xie, Jian-Wei

2015-01-01

T-2 toxin poses a great threat to human health because it has the highest toxicity of the currently known trichothecene mycotoxins. To understand the in vivo toxicity and transformation mechanism of T-2 toxin, we investigated the role of one kind of principal phase I drug-metabolizing enzymes (cytochrome P450 [CYP450] enzymes) on the metabolism of T-2 toxin, which are crucial to the metabolism of endogenous substances and xenobiotics. We also investigated carboxylesterase, which also plays an important role in the metabolism of toxic substances. A chemical inhibition method and a recombinant method were employed to investigate the metabolism of the T-2 toxin by the CYP450 enzymes, and a chemical inhibition method was used to study carboxylesterase metabolism. Samples incubated with human liver microsomes were analyzed by high performance liquid chromatography-triple quadrupole mass spectrometry (HPLC- QqQ MS) after a simple pretreatment. In the presence of a carboxylesterase inhibitor, only 20 % T-2 toxin was metabolized. When CYP enzyme inhibitors and a carboxylesterase inhibitor were both present, only 3 % of the T-2 toxin was metabolized. The contributions of the CYP450 enzyme family to T-2 toxin metabolism followed the descending order CYP3A4, CYP2E1, CYP1A2, CYP2B6 or CYP2D6 or CYP2C19. Carboxylesterase and CYP450 enzymes are of great importance in T-2 toxin metabolism, in which carboxylesterase is predominant and CYP450 has a subordinate role. CYP3A4 is the principal member of the CYP450 enzyme family responsible for T-2 toxin metabolism. The primary metabolite produced by carboxylesterase is HT-2, and the main metabolite produced by CYP 3A4 is 3'-OH T-2. The different metabolites show different toxicities. Our results will provide useful data concerning the toxic mechanism, the safety evaluation, and the health risk assessment of T-2 toxin.

Transcription of CYP19A1 is directly regulated by SF-1 in the theca cells of ovary follicles in chicken.

PubMed

Wang, Jing; Gong, Yanzhang

2017-06-01

Many studies have suggested the important role of estrogen in ovarian differentiation and development of vertebrates including chicken. Cytochrome P450 aromatase, encoded by CYP19A1, is a key enzyme in estrogen synthesis, but the mechanism of CYP19A1 regulation in chicken remains unknown. Here, we found that CYP19A1 was only expressed in the theca cell layers of chicken ovary follicles. Steroidogenic factor 1 (SF-1, also named as nuclear receptor subfamily 5 group A member 1, NR5A1), a potential regulators, was expressed in both the theca cell layers and granulosa cell layers. Forkheadbox L2 (FOXL2), another potential regulator, was only expressed in the granulosa cell layers. Using luciferase assays in vitro, we found that SF-1 could activate the promoter of CYP19A1 by binding to the nuclear receptor half-site (5'-TCAAGGTCA-3') from -280 to -271 base pairs. FOXL2 did not activate the promoter of chicken CYP19A1 gene in either 293T or DF-1 cells. Overexpression of SF-1 in DF-1 cells upregulated aromatase expression, but FOXL2 could not. Taken together, our results indicated that SF-1 activates CYP19A1 mRNA expression via a conserved binding site in chicken ovary, but FOXL2 may not affect the expression of CYP19A1. Copyright © 2017 Elsevier Inc. All rights reserved.

Impact of CYP2C8*3 polymorphism on in vitro metabolism of imatinib to N-desmethyl imatinib.

PubMed

Khan, Muhammad Suleman; Barratt, Daniel T; Somogyi, Andrew A

2016-01-01

1. Imatinib is metabolized to N-desmethyl imatinib by CYPs 3A4 and 2C8. The effect of CYP2C8*3 genotype on N-desmethyl imatinib formation was unknown. 2. We examined imatinib N-demethylation in human liver microsomes (HLMs) genotyped for CYP2C8*3, in CYP2C8*3/*3 pooled HLMs and in recombinant CYP2C8 and CYP3A4 enzymes. Effects of CYP-selective inhibitors on N-demethylation were also determined. 3. A single-enzyme Michaelis-Menten model with autoinhibition best fitted CYP2C8*1/*1 HLM (n = 5) and recombinant CYP2C8 kinetic data (median ± SD Ki = 139 ± 61 µM and 149 µM, respectively). Recombinant CYP3A4 showed two-site enzyme kinetics with no autoinhibition. Three of four CYP2C8*1/*3 HLMs showed single-enzyme kinetics with no autoinhibition. Binding affinity was higher in CYP2C8*1/*3 than CYP2C8*1/*1 HLM (median ± SD Km = 6 ± 2 versus 11 ± 2 µM, P=0.04). CYP2C8*3/*3 (pooled HLM) also showed high binding affinity (Km = 4 µM) and single-enzyme weak autoinhibition (Ki = 449 µM) kinetics. CYP2C8 inhibitors reduced HLM N-demethylation by 47-75%, compared to 0-30% for CYP3A4 inhibitors. 4. In conclusion, CYP2C8*3 is a gain-of-function polymorphism for imatinib N-demethylation, which appears to be mainly mediated by CYP2C8 and not CYP3A4 in vitro in HLM.

Effects of adrenolytic mitotane on drug elimination pathways assessed in vitro.

PubMed

Theile, Dirk; Haefeli, Walter Emil; Weiss, Johanna

2015-08-01

Mitotane (1,1-dichloro-2-(o-chlorophenyl)-2-(p-chlorophenyl)ethane, o,p'-DDD) represents one of the most active drugs for the treatment of adrenocortical carcinoma. Its metabolites 1,1-(o,p'-dichlorodiphenyl) acetic acid (=o,p'-DDA) and 1,1-(o,p'-dichlorodiphenyl)-2,2 dichloroethene (=o,p'-DDE) partly contribute to its pharmacological effects. Because mitotane has a narrow therapeutic index and causes pharmacokinetic drug-drug interactions, knowledge about these compounds' effects on drug metabolizing and transporting proteins is crucial. Using quantitative real-time polymerase chain reaction, our study confirmed the strong inducing effects of o,p'-DDD on mRNA expression of cytochrome P450 3A4 (CYP3A4, 30-fold) and demonstrated that other enzymes and transporters are also induced (e.g., CYP1A2, 8.4-fold; ABCG2 (encoding breast resistance cancer protein, BCRP), 4.2-fold; ABCB1 (encoding P-glycoprotein, P-gp) 3.4-fold). P-gp induction was confirmed at the protein level. o,p'-DDE revealed a similar induction profile, however, with less potency and o,p'-DDA had only minor effects. Reporter gene assays clearly confirmed o,p'-DDD to be a PXR activator and for the first time demonstrated that o,p'-DDE and o,p'-DDA also activate PXR albeit with lower potency. Using isolated, recombinant CYP enzymes, o,p'-DDD and o,p'-DDE were shown to strongly inhibit CYP2C19 (IC50 = 0.05 and 0.09 µM). o,p'-DDA exhibited only minor inhibitory effects. In addition, o,p'-DDD, o,p'-DDE, and o,p'-DDA are demonstrated to be neither substrates nor inhibitors of BCRP or P-gp function. In summary, o,p'-DDD and o,p'-DDE might be potential perpetrators in pharmacokinetic drug-drug interactions through induction of drug-metabolizing enzymes or drug transporters and by potent inhibition of CYP2C19. In tumors over-expressing BCRP or P-gp, o,p'-DDD and its metabolites should retain their efficacy due to a lack of substrate characteristics.

In vitro effects of active constituents and extracts of Orthosiphon stamineus on the activities of three major human cDNA-expressed cytochrome P450 enzymes.

PubMed

Pan, Yan; Abd-Rashid, Badrul Amini; Ismail, Zakiah; Ismail, Rusli; Mak, Joon Wah; Pook, Peter C K; Er, Hui Meng; Ong, Chin Eng

2011-03-15

Orthosiphon stamineus (OS) has been traditionally used to treat diabetes, kidney and urinary disorders, high blood pressure and bone or muscular pain. To assess the possibility of drug-herb interaction via interference of metabolism, effects of four OS extracts of different polarity and three active constituents (sinensetin, eupatorin and rosmarinic acid) on major human cDNA-expressed cytochrome P450 (CYP) enzymes were investigated. Three substrate-probe based high-performance liquid chromatography (HPLC) assays were established to serve as activity markers for CYP2C9, CYP2D6 and CYP3A4. Our results indicate that OS extracts and constituents exhibited differential modulatory effects on different CYPs. While none of the OS components showed significant inhibition on CYP2C9, eupatorin strongly and uncompetitively inhibited CYP2D6 activity with a K(i) value of 10.2μM. CYP3A4 appeared to be the most susceptible enzyme to OS inhibitory effects. It was moderately inhibited by OS dichloromethane and petroleum ether extract with mixed-type and noncompetitive inhibitions (K(i)=93.7 and 44.9μg/mL), respectively. Correlation study indicated that the inhibition was accounted for by the presence of eupatorin in the extracts. When IC(50) values of these extracts were expressed in volume per dose unit to reflect inhibitory effect at recommended human doses from commercially available products, moderate inhibition was also observed. In addition, CYP3A4 was strongly and noncompetitively inhibited by eupatorin alone, with a K(i) value of 9.3μM. These findings suggest that co-administration of OS products, especially those with high eupatorin content, with conventional drugs may have the potential to cause drug-herb interactions involving inhibition of major CYP enzymes. 2011 Elsevier Ireland Ltd. All rights reserved.

Information theory-based analysis of CYP2C19, CYP2D6 and CYP3A5 splicing mutations.

PubMed

Rogan, Peter K; Svojanovsky, Stan; Leeder, J Steven

2003-04-01

Several mutations are known or suspected to affect mRNA splicing of CYP2C19, CYP2D6 and CYP3A5 genes; however, little experimental evidence exists to support these conclusions. The present study applies mathematical models that measure changes in information content of splice sites in these genes to demonstrate the relationship between the predicted phenotypes of these variants to the corresponding genotypes. Based on information analysis, the CYP2C19*2 variant activates a new cryptic site 40 nucleotides downstream of the natural splice site. CYP2C19*7 abolishes splicing at the exon 5 donor site. The CYP2D6*4 allele similarly inactivates splicing at the acceptor site of exon 4 and activates a new cryptic site one nucleotide downstream of the natural acceptor. CYP2D6*11 inactivates the acceptor site of exon 2. The CYP3A5*3 allele activates a new cryptic site 236 nucleotides upstream of the exon 4 natural acceptor site. CYP3A5*5 inactivates the exon 5 donor site and CYP3A5*6 strengthens a site upstream of the natural donor site, resulting in skipping of exon 7. Other previously described missense and nonsense mutations at terminal codons of exons in these genes affected splicing. CYP2D6*8 and CYP2D6*14 both decrease the strength of the exon 3 donor site, producing transcripts lacking this exon. The results of information analysis are consistent with the poor metabolizer phenotypes observed in patients with these mutations, and illustrate the potential value of these mathematical models to quantitatively evaluate the functional consequences of new mutations suspected of altering mRNA splicing.

The Karolinska cocktail for phenotyping of five human cytochrome P450 enzymes.

PubMed

Christensen, Magnus; Andersson, Katarina; Dalén, Per; Mirghani, Rajaa A; Muirhead, Gary J; Nordmark, Anna; Tybring, Gunnel; Wahlberg, Anneli; Yaşar, Umit; Bertilsson, Leif

2003-06-01

Our objectives were (1) to determine whether the drugs caffeine, losartan, omeprazole, debrisoquin (INN, debrisoquine), and quinine can be given simultaneously in low doses as a cocktail for the phenotyping of cytochrome P450 (CYP) 1A2, 2C9, 2C19, 2D6, and 3A4, respectively, and (2) to design an administration schedule to give as few sampling occasions as possible. Twenty-four subjects were given oral doses of 100 mg caffeine, 25 mg losartan, 20 mg omeprazole, 10 mg debrisoquin, and 250 mg quinine on separate days. After a washout period of at least 4 days, all drugs were given simultaneously except for quinine, which was given 8 hours after the other drugs. Blood and urine samples were collected to determine parent drug and metabolite concentrations for assessment of phenotyping indices. Any difference between both single and cocktail doses was tested on a log-normal distribution. The phenotypic indices of CYP1A2 (paraxanthine/caffeine in 4-hour plasma), CYP2C9 (losartan/E-3174 [metabolite of losartan] in 0- to 8-hour urine), CYP2C19 (omeprazole/5-hydroxyomeprazole in 3-hour plasma), and CYP3A4 (quinine/3-hydroxyquinine in 16-hour plasma) were not significantly changed when probe drugs were administered alone compared with together, although a tendency toward higher concentrations of losartan was seen during simultaneous administration (95% confidence interval, 0.51-1.002; P =.051). The CYP2D6 phenotypic index (debrisoquin/4-hydroxydebrisoquin in 0- to 8-hour urine) was significantly changed when drugs were given together (95% confidence interval, 0.45-0.87; P =.007), indicating an inhibition of the debrisoquin metabolism. The within-subject coefficients of variation (8%-25%) were much lower than the between-subject coefficients of variation (34%-79%). The administration of drugs together suggests an inhibition of debrisoquin metabolism caused by the concurrent drugs given. By separating debrisoquin from the other cocktail drugs, this method is likely to be used as a tool to phenotype the enzymes CYP1A2, CYP2C9, CYP2C19, CYP2D6, and CYP3A4 with only 2 urinary collections and 2 blood-sampling occasions.

Interactions of 2,4,6-trinitrotoluene (TNT) with xenobiotic biotransformation system in European eel Anguilla anguilla (Linnaeus, 1758).

PubMed

Della Torre, Camilla; Corsi, Ilaria; Arukwe, Augustine; Valoti, Massimo; Focardi, Silvano

2008-11-01

The aim of the present study was to investigate the interaction of 2,4,6-trinitrotoluene (TNT) with liver biotransformation enzymes in European eel Anguilla anguilla (Linnaeus, 1758). Eels were exposed to 0.5, 1 and 2.5mg/l nominal concentrations of TNT for 6 and 24h. Modulation of CYP1A1, UDPGT and GST genes was investigated by real-time PCR. Total CYP450 content, NADPH cytochrome c reductase activity, CYP1A and CYP2B-like activities, such as EROD, MROD and BROD, as well as GST and UDPGT activities, were measured by biochemical assays. An in vitro study was performed on EROD in order to evaluate catalytic modulation by TNT. No modulation of the CYP1A1 gene or protein was observed in TNT-exposed eels. On the other hand, a significant decline of EROD and MROD activities was observed in vivo. An increase in NADPH cyt c reductase, and phase II enzymes (UDPGT and GST) were observed at both gene expression and activity levels. The overall results indicated that TNT is a potential competitive inhibitor of CYP1A activities. A TNT metabolic pathway involving NADPH cyt c reductase and phase II enzymes is also suggested.

Investigation of cytochrome P450 inhibitory properties of maslinic acid, a bioactive compound from Olea europaea L., and its structure-activity relationship.

PubMed

Sun, Min; Tang, Yu; Ding, Tonggui; Liu, Mingyao; Wang, Xin

2015-01-15

Maslinic acid (MA), the main pentacyclic triterpene of Olea europaea L. fruit, possesses a variety of pharmacological actions, including hypoglycemic, antioxidant, cardioprotective and antitumoral activities. Despite its importance, little is known about its effects on the cytochrome P450 (CYP) activity in both humans and animals. Therefore, the aim of this study was to investigate the effects of MA on the CYP 1A2, 2C9/11, 2D1/6, 2E1 and 3A2/4 activities by human and rat liver microsomes and specific CYP isoforms. In humans, MA only weakly inhibited CYP3A4 activity in human liver microsomes and specific CYP3A4 isoform with IC50 value at 46.1 and 62.3µM, respectively. In rats, MA also exhibited weak inhibition on CYP2C11, CYP2E1 and CYP3A2 activities with IC50 values more than 100µM. Enzyme kinetic studies showed that the MA was not only a competitive inhibitor of CYP3A4 in humans, but also a competitive inhibitor of CYP2C11 and 3A2 in rats, with Ki of 18.4, 98.7 and 66.3µM, respectively. Moreover, the presence of hydroxyl group at C-2 position of triterpenic acid in MA compared with oleanolic acid could magnify its competitive inhibition on human CYP3A4 activity. The relatively high Ki values of MA would have a low potential to cause the possible toxicity and drug interactions involving CYP enzymes, thus suggesting a sufficient safety for its putative use as a nutraceutical taken together with drugs. Copyright © 2014 Elsevier GmbH. All rights reserved.

Association analysis of CYP2C9*3 and phenytoin-induced severe cutaneous adverse reactions (SCARs) in Thai epilepsy children.

PubMed

Suvichapanich, Supharat; Jittikoon, Jiraphun; Wichukchinda, Nuanjun; Kamchaisatian, Wasu; Visudtibhan, Anannit; Benjapopitak, Suwat; Nakornchai, Somjai; Manuyakorn, Wiparat; Mahasirimongkol, Surakameth

2015-08-01

CYP2C9 is the key enzyme in aromatic antiepileptic drugs (AEDs) metabolism. CYP2C9*3 is a loss of function polymorphism. This study was designed to investigate genetic association between CYP2C9*3 and aromatic AED-induced severe cutaneous adverse reactions (SCARs) in Thai children. The 37 aromatic AED-induced SCARs patients (20 phenobarbital and 17 phenytoin) and 35 tolerances (19 phenobarbital and 16 phenytoin) were enrolled. CYP2C9*3 was genotyped by allele-specific PCRs. The association between CYP2C9*3 with phenytoin-induced SCARs and phenobarbital-induced SCARs were analyzed in comparison with tolerances and healthy samples. Significant association between phenytoin-induced SCARs and CYP2C9*3 was discovered (odds ratio=14.52; 95% confidence interval (CI)=1.18-∞, P-value=0.044). CYP2C9*3 was not associated with phenobarbital-induced SCARs. This study is the first report of CYP2C9*3 association to phenytoin-induced SCARs in Thai epileptic children. The CYP2C9*3 is a reasonable predictive genetic marker to anticipate SCARs from phenytoin.

Effect of zolpidem on human cytochrome P450 activity, and on transport mediated by P-glycoprotein.

PubMed

von Moltke, Lisa L; Weemhoff, James L; Perloff, Michael D; Hesse, Leah M; Harmatz, Jerold S; Roth-Schechter, Barbara F; Greenblatt, David J

2002-12-01

The influence of high concentrations of zolpidem (100 microM, corresponding to approximately 200 times maximum therapeutic concentrations) on the activity of six human Cytochrome P450 (CYP) enzymes was evaluated in a model system using human liver microsomes. Zolpidem produced negligible or weak inhibition of human CYP1A2, 2B6, 2C9, 2C19, 2D6, and 3A. Transport of rhodamine 123, presumed to be mediated mainly by the energy-dependent efflux transport protein P-glycoprotein, was studied in a cell culture system using a human intestinal cell line. High concentrations of zolpidem (100 microM), exceeding the usual therapeutic range by more than 100-fold, produced only modest impairment of rhodamine 123 transport. The findings indicate that zolpidem is very unlikely to cause clinical drug interactions attributable to impairment of CYP activity or P-gp mediated transport. Copyright 2002 John Wiley & Sons, Ltd.

Biological definition of multiple chemical sensitivity from redox state and cytokine profiling and not from polymorphisms of xenobiotic-metabolizing enzymes

DOE Office of Scientific and Technical Information (OSTI.GOV)

De Luca, Chiara; Scordo, Maria G.; Cesareo, Eleonora

Background: Multiple chemical sensitivity (MCS) is a poorly clinically and biologically defined environment-associated syndrome. Although dysfunctions of phase I/phase II metabolizing enzymes and redox imbalance have been hypothesized, corresponding genetic and metabolic parameters in MCS have not been systematically examined. Objectives: We sought for genetic, immunological, and metabolic markers in MCS. Methods: We genotyped patients with diagnosis of MCS, suspected MCS and Italian healthy controls for allelic variants of cytochrome P450 isoforms (CYP2C9, CYP2C19, CYP2D6, and CYP3A5), UDP-glucuronosyl transferase (UGT1A1), and glutathione S-transferases (GSTP1, GSTM1, and GSTT1). Erythrocyte membrane fatty acids, antioxidant (catalase, superoxide dismutase (SOD)) and glutathione metabolizing (GST,more » glutathione peroxidase (Gpx)) enzymes, whole blood chemiluminescence, total antioxidant capacity, levels of nitrites/nitrates, glutathione, HNE-protein adducts, and a wide spectrum of cytokines in the plasma were determined. Results: Allele and genotype frequencies of CYPs, UGT, GSTM, GSTT, and GSTP were similar in the Italian MCS patients and in the control populations. The activities of erythrocyte catalase and GST were lower, whereas Gpx was higher than normal. Both reduced and oxidised glutathione were decreased, whereas nitrites/nitrates were increased in the MCS groups. The MCS fatty acid profile was shifted to saturated compartment and IFNgamma, IL-8, IL-10, MCP-1, PDGFbb, and VEGF were increased. Conclusions: Altered redox and cytokine patterns suggest inhibition of expression/activity of metabolizing and antioxidant enzymes in MCS. Metabolic parameters indicating accelerated lipid oxidation, increased nitric oxide production and glutathione depletion in combination with increased plasma inflammatory cytokines should be considered in biological definition and diagnosis of MCS.« less

Cytochrome P450 induction by rifampicin in healthy subjects: determination using the Karolinska cocktail and the endogenous CYP3A4 marker 4beta-hydroxycholesterol.

PubMed

Kanebratt, K P; Diczfalusy, U; Bäckström, T; Sparve, E; Bredberg, E; Böttiger, Y; Andersson, T B; Bertilsson, L

2008-11-01

The Karolinska cocktail, comprising caffeine, losartan, omeprazole, and quinine, was given before and after administration of rifampicin (20, 100, or 500 mg daily) to measure induction of cytochrome P450 (P450) enzymes. Rifampicin was given for 14 days to eight healthy subjects (all of whom possessed at least one wild-type CYP2C9 and one wild-type CYP2C19 gene) in each dose group. 4beta-hydroxycholesterol was assessed as an endogenous marker of CYP3A4 induction. A fourfold induction of CYP3A4 was seen at the highest dose by both quinine:3'-hydroxyquinine and 4beta-hydroxycholesterol measurements (P < 0.001). CYP3A4 was also induced at the two lower doses of rifampicin when measured by these two markers (P < 0.01 or P < 0.001). CYP1A2, CYP2C9, and CYP2C19 were induced after 500 mg rifampicin daily (1.2-fold, P < 0.05; 1.4-fold, P < 0.05; and 4.2-fold, P < 0.01, respectively). In conclusion, we have shown that the Karolinska cocktail and 4beta-hydroxycholesterol can be used for an initial screening of the induction properties of a drug candidate.

Linkage disequilibrium between the CYP2C19*2,*17 and CYP2C9*1 alleles and impact of VKORC1, CYP2C9, CYP2C19 gene polymorphisms and gene-gene interactions on warfarin therapy.

PubMed

Khalighi, Koroush; Cheng, Gang; Mirabbasi, Seyedabbas; Khalighi, Bahar; Wu, Yin; Fan, Wuqiang

2017-01-01

Warfarin therapy is complicated by its large inter-individual and intra-individual variability. Both genetic and non-genetic factors can affect warfarin therapy. This study aims to investigate the allele distribution of VKORC1, CYP2C9 and CYP2C19, contribution of different allele variants and possible gene-gene interaction on warfarin therapy. Four hundreds and ninety-two patients were enrolled and single nucleotide polymorphisms for vitamin K epoxide reductase complex subunit 1 (VKORC1), cytochrome P450 CYP2C9 and cytochrome P450 CYP2C19 were genotyped. CYP2C9*1 allele is in complete linkage disequilibrium with CYP2C19*2 and CYP2C19*17 (D' = 1) in our study population. Patient with VKORC1-1639 G > A, CYP2C9*2 and CYP2C9*3 genetic variants need significant lower warfarin dose than patient with wild type allele of VKORC1 1639 G or CYP2C9*1. There is no significant differences between CYP2C19 allele variants for warfarin stable dose and INR > 5 event. Because of the complete linkage disequilibrium between CYP2C19*2,*17 and CYP2C9*1, patient with CYP2C19 *2/*2, *2/*17 and *17/*17 genotypes tend to have higher warfarin dose than patient with CYP2C19*1/*1 genotype. Stepwise regression analysis showed that VKORC1, CYP2C9, body mass index (BMI), age and gender were included as a factor significantly contributing to warfarin dose, whereas CYP2C19 did not contribute to warfarin dose. No statistically significant interaction between CYP2C9 and VKORC1 on warfarin dose and INR > 5 event was detected in univariate general linear model analysis. Our study suggests that polymorphic variants of VKORC1 and CYP2C9 affect warfarin dose independently, whereas CYP2C19 did not contribute to warfarin therapy.

Polysaccharide peptides from Coriolus versicolor competitively inhibit model cytochrome P450 enzyme probe substrates metabolism in human liver microsomes.

PubMed

Yeung, John H K; Or, Penelope M Y

2012-03-15

Polysaccharide peptide (PSP), isolated from COV-1 strain of Coriolus versicolor, is commonly used as an adjunct in cancer chemotherapy or health supplement in China. Previous studies have shown that PSP decreased antipyrine clearance and inhibited rat CYP2C11-mediated tolbutamide 4-hydroxylation and in human CYP2C9. In this study, the effects of the water extractable fraction of PSP on the metabolism of model CYP1A2, CYP2D6, CYP2E1 and CYP3A4 probe substrates were investigated in pooled human liver microsomes. PSP (1.25-20μM) dose-dependently decreased CYP1A2-mediated metabolism of phenacetin to paracetamol (IC(50) 19.7μM) and CYP3A4-mediated metabolism of testosterone to 6β-hydroxytestosterone (IC(20) 7.06μM). Enzyme kinetics studies showed the inhibition of CYP1A2 activity was competitive and concentration-dependent (K(i)=18.4μM). Inhibition of testosterone to 6β-hydroxytestosterone was also competitive and concentration-dependent (K(i)=31.8μM). Metabolism of dextromethorphan to dextrorphan (CYP2D6-mediated) and chlorzoxazone to 6-hydroxychlorzoxazone (CYP2E1-mediated) was only minimally inhibited by PSP, with IC(20) values at 15.6μM and 11.9μM, respectively. This study demonstrated that PSP competitively inhibited the CYP1A2- and CYP3A4-mediated metabolism of model probe substrates in human liver microsomes in vitro. The relatively high K(i) values for CYP1A2 and CYP3A4 would suggest a low potential for PSP to cause herb-drug interaction related to these CYP isoforms. Copyright © 2011 Elsevier GmbH. All rights reserved.

Double function hydroperoxide lyases/epoxyalcohol synthases (CYP74C) of higher plants: identification and conversion into allene oxide synthases by site-directed mutagenesis.

PubMed

Toporkova, Yana Y; Gorina, Svetlana S; Bessolitsyna, Elena K; Smirnova, Elena O; Fatykhova, Valeria S; Brühlmann, Fredi; Ilyina, Tatiana M; Mukhtarova, Lucia S; Grechkin, Alexander N

2018-04-01

The CYP74C subfamily of fatty acid hydroperoxide transforming enzymes includes hydroperoxide lyases (HPLs) and allene oxide synthases (AOSs). This work reports a new facet of the putative CYP74C HPLs. Initially, we found that the recombinant CYP74C13_MT (Medicago truncatula) behaved predominantly as the epoxyalcohol synthase (EAS) towards the 9(S)-hydroperoxide of linoleic acid. At the same time, the CYP74C13_MT mostly possessed the HPL activity towards the 13(S)-hydroperoxides of linoleic and α-linolenic acids. To verify whether this dualistic behaviour of CYP74C13_MT is occasional or typical, we also examined five similar putative HPLs (CYP74C). These were CYP74C4_ST (Solanum tuberosum), CYP74C2 (Cucumis melo), CYP74C1_CS and CYP74C31 (both of Cucumis sativus), and CYP74C13_GM (Glycine max). All tested enzymes behaved predominantly as EAS toward 9-hydroperoxide of linoleic acid. Oxiranyl carbinols such as (9S,10S,11S,12Z)-9,10-epoxy-11-hydroxy-12-octadecenoic acids were the major EAS products. Besides, the CYP74C31 possessed an additional minor 9-AOS activity. The mutant forms of CYP74C13_MT, CYP74C1_CS, and CYP74C31 with substitutions at the catalytically essential domains, namely the "hydroperoxide-binding domain" (I-helix), or the SRS-1 domain near the N-terminus, showed strong AOS activity. These HPLs to AOSs conversions were observed for the first time. Until now a large part of CYP74C enzymes has been considered as 9/13-HPLs. Notwithstanding, these results show that all studied putative CYP74C HPLs are in fact the versatile HPL/EASs that can be effortlessly mutated into specific AOSs. Copyright © 2018 Elsevier B.V. All rights reserved.

Novel triterpene oxidizing activity of Arabidopsis thaliana CYP716A subfamily enzymes.

PubMed

Yasumoto, Shuhei; Fukushima, Ery O; Seki, Hikaru; Muranaka, Toshiya

2016-02-01

Triterpenoids have diverse chemical structures and bioactivities. Cytochrome P450 monooxygenases play a key role in their structural diversification. In higher plants, CYP716A subfamily enzymes are triterpene oxidases. In this study, Arabidopsis thaliana CYP716A1 and CYP716A2 were characterized by heterologously expressing them in simple triterpene-producing yeast strains. In contrast to the C-28 oxidative activity of CYP716A1 shown in several CYP716A subfamily enzymes, remarkably, CYP716A2 displayed 22α-hydroxylation activity against α-amyrin that has not been previously reported, which produces the cytotoxic triterpenoid, 22α-hydroxy-α-amyrin. Our results contribute to the enrichment of the molecular toolbox that allows for the combinatorial biosynthesis of diverse triterpenoids. © 2016 Federation of European Biochemical Societies.

Cloning and Functional Characterization of the Maize (Zea mays L.) Carotenoid Epsilon Hydroxylase Gene

PubMed Central

Sheng, Yanmin; Wang, Yingdian; Capell, Teresa; Shi, Lianxuan; Ni, Xiuzhen; Sandmann, Gerhard; Christou, Paul; Zhu, Changfu

2015-01-01

The assignment of functions to genes in the carotenoid biosynthesis pathway is necessary to understand how the pathway is regulated and to obtain the basic information required for metabolic engineering. Few carotenoid ε-hydroxylases have been functionally characterized in plants although this would provide insight into the hydroxylation steps in the pathway. We therefore isolated mRNA from the endosperm of maize (Zea mays L., inbred line B73) and cloned a full-length cDNA encoding CYP97C19, a putative heme-containing carotenoid ε hydroxylase and member of the cytochrome P450 family. The corresponding CYP97C19 genomic locus on chromosome 1 was found to comprise a single-copy gene with nine introns. We expressed CYP97C19 cDNA under the control of the constitutive CaMV 35S promoter in the Arabidopsis thaliana lut1 knockout mutant, which lacks a functional CYP97C1 (LUT1) gene. The analysis of carotenoid levels and composition showed that lutein accumulated to high levels in the rosette leaves of the transgenic lines but not in the untransformed lut1 mutants. These results allowed the unambiguous functional annotation of maize CYP97C19 as an enzyme with strong zeinoxanthin ε-ring hydroxylation activity. PMID:26030746

Nitrophenols isolated from diesel exhaust particles regulate steroidogenic gene expression and steroid synthesis in the human H295R adrenocortical cell line

DOE Office of Scientific and Technical Information (OSTI.GOV)

Furuta, Chie; Laboratory of Veterinary Physiology, Department of Veterinary Medicine, Faculty of Agriculture, Tokyo University of Agriculture and Technology, Tokyo 183-8509; Noda, Shiho

2008-05-15

Studies of nitrophenols isolated from diesel exhaust particles (DEPs), 3-methyl-4-nitrophenol (PNMC) and 4-nitro-3-phenylphenol (PNMPP) have revealed that these chemicals possess estrogenic and anti-androgenic activity in vitro and in vivo and that PNMC accumulate in adrenal glands in vivo. However, the impacts of exposure to these compounds on adrenal endocrine disruption and steroidogenesis have not been investigated. To elucidate the non-receptor mediated effects of PNMC and PNMPP, we investigated the production of the steroid hormones progesterone, cortisol, testosterone, and estradiol-17{beta} and modulation of nine major enzyme genes involved in the synthesis of steroid hormones (CYP11A, CYP11B1, CYP17, CYP19, 17{beta}HSD1, 17{beta}HSD4, CYP21,more » 3{beta}HSD2, StAR) in human adrenal H295R cells supplied with cAMP. Exposure to 10{sup -7} to 10{sup -5} M PNMC and 1 mM 8-Br-cAMP for 48 h decreased testosterone, cortisol, and estradiol-17{beta} levels and increased progesterone secretion. At 10{sup -5} M, PNMC with 1 mM 8-Br-cAMP significantly stimulated expression of the 17{beta}HSD4 and significantly suppressed expression of 3{beta}HSD2. In comparison, 10{sup -7} to 2 x 10{sup -5} M PNMPP with 1 mM 8-Br-cAMP for 48 h decreased concentrations of estradiol-17{beta}, increased progesterone levels, but did not affect testosterone and cortisol secretion due to the significant suppression of CYP17 and the non-significant but obvious suppression of CYP19. Our results clarified steroidogenic enzymes as candidates responsible for the inhibition or stimulation for the production of steroid hormones in the steroidogenic pathway, thus providing the first experimental evidence for multiple mechanisms of disruption of endocrine pathways by these nitrophenols.« less

Identification of human cytochrome P450 enzymes involved in the metabolism of IN-1130, a novel activin receptor-like kinase-5 (ALK5) inhibitor.

PubMed

Kim, Y W; Kim, Y K; Kim, D-K; Sheen, Y Y

2008-05-01

1. The in vitro metabolism of 3-((5-(6-methylpyridin-2-yl)-4-(quinoxalin-6-yl)-1H-imidazol-2-yl)methyl)benzamide (IN-1,130), a selective activin receptor-like kinase-5 (ALK5) inhibitor and a candidate drug for fibrotic disease, was studied. 2. The cytochrome P450s (CYPs) responsible for metabolism of IN-1,130 in liver microsomes of rat, mouse, dog, monkey and human, and in human CYP supersomestrade mark, were identified using specific CYP inhibitors. The order of disappearance of IN-1,130 in various liver microsomal systems studied was as follows: monkey, mouse, rat, human, and dog. 3. Five distinct metabolites (M1-M5) were identified in all the above microsomes and their production was substantially inhibited by CYP inhibitors such as SKF-525A and ketoconazole. Among nine human CYP supersomestrade mark examined, CYP3A4, CYP2C8, CYP2D6 1, and CYP2C19 were involved in the metabolism of IN-1,130, and the production of metabolites were significantly inhibited by specific CYP inhibitors. IN-1,130 disappeared fastest in CYP2C8 supersomes. CYP3A4 produced four metabolites of IN-1,130 (M1-M4), whereas supersomes expressing human FMO cDNAs, such as FMO1, FMO3, and FMO5, produced no metabolites. 4. Hence, it is concluded that metabolism of IN-1,130 is mediated by CYP3A4, CYP2C8, CYP2D6 1, and CYP2C19.

Correspondence between the CYP2C19 and CYP3A4 genotypes with the inferred metabolizer phenotype by omeprazole administration in Mexican healthy children.

PubMed

Favela-Mendoza, A F; Martínez-Cortes, G; Romero-Prado, M M; Romero-Tejeda, E M; Islas-Carbajal, M C; Sosa-Macias, M; Lares-Asseff, I; Rangel-Villalobos, H

2018-05-07

CYP2C19 genotypes presumably allow the prediction of the metabolizer phenotypes: poor (PMs), extensive (EMs) and ultra-rapid (UMs). However, evidence from previous studies regarding this predictive power is unclear, which is important because the benefits expected by healthcare institutions and patients are based on this premise. Therefore, we aimed to complete a formal evaluation of the diagnostic value of CYP2C19 and CYP3A4 genes for predicting metabolizer phenotypes established by omeprazole (OME) administration in 118 healthy children from Jalisco (western Mexico). The genotypes for CYP3A4*1B and CYP2C19*2, *3, *4, *5 and *17 alleles were determined. CYP2C19 and CYP3A4 phenotypes were obtained after 20 mg OME administration and HPLC quantification in plasma to estimate the Hydroxylation Index (HI = OME/HOME) and Sulfonation Index (SI = OME/SOME), respectively. The distribution of genotypes and phenotypes for CYP2C19 and CYP3A4 was similar to previous studies in Mexico and Latin America. We estimated the CYP2C19 UM, EM and PM phenotype frequency in 0.84%, 96.61% and 2.54%, respectively. Although differences in the HI distribution were observed between CYP2C19 genotypes, they showed a poor diagnostic ability to predict the CYP2C19 metabolizer phenotype. Similarly, the number of CYP2C19 and CYP3A4 functional alleles was correlated with the HI distribution, but also their diagnostic ability to predict the CYP2C19 phenotype was poor. The CYP2C19 phenotype is not predicted by the number of functional alleles of CYP2C19 and CYP3A4 genes. Phenotyping is still the most valuable alternative to dose individualization for CYP2C19 substrate drugs. © 2018 John Wiley & Sons Ltd.

Genetic Polymorphisms of Cytochrome P450 Enzymes and Transport Proteins in a Russian Population and Three Ethnic Groups of Dagestan.

PubMed

Mirzaev, Karin B; Sychev, Dmitry A; Ryzhikova, Kristina A; Konova, Olga D; Mammaev, Suleiman N; Gafurov, Daniyal M; Shuev, Grigorij N; Grishina, Elena A; Sozaeva, Zhannet A

2017-12-01

The objective of this study was to investigate the prevalence of polymorphic markers of the CYP2C19, CYP2C9, CYP2D6, SLCO1B1, and ABCB1 genes among the three ethnic groups in Dagestan and compare it with the carrier frequency of these markers among the Russian population living in Moscow. The study involved 186 healthy, unrelated, and chronic medication-free volunteers (53 males and 133 females) of the three ethnic groups in the Dagestan Republic: 46 Laks, 90 Avars, and 50 Dargins. Genotyping was performed using real-time polymerase chain reaction-based methods. The allelic prevalences of the three Dagestan peoples were compared with ethnic Russians from the Moscow region. Statistically significant differences for the following gene polymorphisms: CYP2C19*17, CYP2C9*3, ABCB1 (C3435T), SLCO1B1*5 were found between the Russian population and the three ethnic groups of the Dagestan republic. The data obtained from this study will help with prioritization genotyping in the region.

[Effect of clinical doses of Realgar-Indigo Naturalis formula and large-dose of realgar on CYP450s of rat liver].

PubMed

Xu, Huan-Hua; Wang, Mei-Xi; Tan, Hong-Ling; Wang, Yu-Guang; Tang, Xiang-Lin; Xiao, Cheng-Rong; Li, Hua; Gao, Yue; Ma, Zeng-Chun

2017-02-01

To investigate the effect of clinical dose of Realgar-Indigo Naturais formula (RIF) and large-dose of Realgar on main drug-metabolizing enzymes CYP450s of rat liver, as well as its regulatory effect on mRNA expression. Wistar rats were administrated orally with tested drugs for 14 days. A Cocktail method combined with HPLC-MS/MS was used in the determination of 4 cytochrome P450 isozymes (CYP1A2, CYP2B, CYP3A and CYP2C) in liver of the rats, and the mRNA expression levels of the above subtypes were detected by real-time fluorescent quantitative PCR. The results showed that RIF can significantly induce CYP1A2 and CYP2B enzyme activity, and inhibit CYP3A enzyme activity. This result was consistent with the mRNA expression. However, its single compound showed weaker or even contrary phenomenon. Different doses of Realgar also showed significant inconsistencies on CYP450 enzymes activity and mRNA expression. These phenomena may be relevant with RIF compatibility synergies or toxicity reduction. The results can also prompt drug interactions when RIF is combined with other medicines in application. Copyright© by the Chinese Pharmaceutical Association.

Estimation of the Contribution of CYP2C8 and CYP3A4 in Repaglinide Metabolism by Human Liver Microsomes Under Various Buffer Conditions.

PubMed

Kudo, Toshiyuki; Goda, Hitomi; Yokosuka, Yuki; Tanaka, Ryo; Komatsu, Seina; Ito, Kiyomi

2017-09-01

We have previously reported that the microsomal activities of CYP2C8 and CYP3A4 largely depend on the buffer condition used in in vitro metabolic studies, with different patterns observed between the 2 isozymes. In the present study, therefore, the possibility of buffer condition dependence of the fraction metabolized by CYP2C8 (fm2C8) for repaglinide, a dual substrate of CYP2C8 and CYP3A4, was estimated using human liver microsomes under various buffer conditions. Montelukast and ketoconazole showed a potent and concentration-dependent inhibition of CYP2C8-mediated paclitaxel 6α-hydroxylation and CYP3A4-mediated triazolam α-hydroxylation, respectively, without dependence on the buffer condition. Repaglinide depletion was inhibited by both inhibitors, but the degree of inhibition depended on buffer conditions. Based on these results, the contribution of CYP2C8 in repaglinide metabolism was estimated to be larger than that of CYP3A4 under each buffer condition, and the fm2C8 value of 0.760, estimated in 50 mM phosphate buffer, was the closest to the value (0.801) estimated in our previous modeling analysis based on its concentration increase in a clinical drug interaction study. Researchers should be aware of the possibility of buffer condition affecting the estimated contribution of enzyme(s) in drug metabolism processes involving multiple enzymes. Copyright © 2017 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Influence of genetic variants of CYP2D6, CYP2C9, CYP2C19 and CYP3A4 on antiepileptic drug metabolism in pediatric patients with refractory epilepsy.

PubMed

López-García, Miguel A; Feria-Romero, Iris A; Serrano, Héctor; Rayo-Mares, Darío; Fagiolino, Pietro; Vázquez, Marta; Escamilla-Núñez, Consuelo; Grijalva, Israel; Escalante-Santiago, David; Orozco-Suarez, Sandra

2017-06-01

Identified the polymorphisms of CYP2D6, CYP2C9, CYP2C19 and CYP3A4, within a rigorously selected population of pediatric patients with drug-resistant epilepsy. The genomic DNA of 23 drug-resistant epilepsy patients and 7 patients with good responses were analyzed. Ten exons in these four genes were genotyped, and the drug concentrations in saliva and plasma were determined. The relevant SNPs with pharmacogenomics relations were CYP2D6*2 (rs16947) decreased your activity and CYP2D6*4 (rs1065852), CYP2C19*2 (rs4244285) and CYP3A4*1B (rs2740574) by association with poor metabolizer. The strongest risk factors were found in the AA genotype and allele of SNP rs3892097 from the CYP2D6 gene, followed by the alleles A and T of SNPs rs2740574 and rs2687116, respectively from CYP3A4. The most important concomitance was between homozygous genotype AA of rs3892097 and genotype AA of rs2740574 with 78.3% in drug-resistant epilepsy patients as compared to 14.3% in control patients. The results demonstrated the important role of the CYP 3A4*1B allelic variant as risk factor for developing drug resistance and CYP2D6, CYP2C19 SNPs and haplotypes may affect the response to antiepileptic drugs. Copyright © 2017. Published by Elsevier Urban & Partner Sp. z o.o.

The Role of Human Cytochrome P450 Enzymes in the Formation of 2-Hydroxymetronidazole: CYP2A6 is the High Affinity (Low Km) Catalyst

PubMed Central

Cohen-Wolkowiez, Michael; Sampson, Mario R.; Kearns, Gregory L.

2013-01-01

Despite metronidazole’s widespread clinical use since the 1960s, the specific enzymes involved in its biotransformation have not been previously identified. Hence, in vitro studies were conducted to identify and characterize the cytochrome P450 enzymes involved in the formation of the major metabolite, 2-hydroxymetronidazole. Formation of 2-hydroxymetronidazole in human liver microsomes was consistent with biphasic, Michaelis-Menten kinetics. Although several cDNA-expressed P450 enzymes catalyzed 2-hydroxymetronidazole formation at a supratherapeutic concentration of metronidazole (2000 μM), at a “therapeutic concentration” of 100 μM only CYPs 2A6, 3A4, 3A5, and 3A7 catalyzed metronidazole 2-hydroxylation at rates substantially greater than control vector, and CYP2A6 catalyzed 2-hydroxymetronidazole formation at rates 6-fold higher than the next most active enzyme. Kinetic studies with these recombinant enzymes revealed that CYP2A6 has a Km = 289 μM which is comparable to the Km for the high-affinity (low-Km) enzyme in human liver microsomes, whereas the Km values for the CYP3A enzymes corresponded with the low-affinity (high-Km) component. The sample-to-sample variation in 2-hydroxymetronidazole formation correlated significantly with CYP2A6 activity (r ≥ 0.970, P < 0.001) at substrate concentrations of 100 and 300 μM. Selective chemical inhibitors of CYP2A6 inhibited metronidazole 2-hydroxylation in a concentration-dependent manner and inhibitory antibodies against CYP2A6 virtually eliminated metronidazole 2-hydroxylation (>99%). Chemical and antibody inhibitors of other P450 enzymes had little or no effect on metronidazole 2-hydroxylation. These results suggest that CYP2A6 is the primary catalyst responsible for the 2-hydroxylation of metronidazole, a reaction that may function as a marker of CYP2A6 activity both in vitro and in vivo. PMID:23813797

Influences of Realgar-Indigo naturalis, A Traditional Chinese Medicine Formula, on the Main CYP450 Activities in Rats Using a Cocktail Method

PubMed Central

Xu, Huan-Hua; Hao, Fei-Ran; Wang, Mei-Xi; Ren, Si-Jia; Li, Ming; Tan, Hong-Ling; Wang, Yu-Guang; Tang, Xiang-Lin; Xiao, Cheng-Rong; Liang, Qian-De

2017-01-01

The purpose of this work was to study the influences of Realgar-Indigo naturalis (RIF) and its principal element realgar on 4 main cytochrome P450 enzymes activities in rats. A simple and efficient cocktail method was developed to detect the four probe drugs simultaneously. In this study, Wistar rats were administered intragastric RIF and realgar for 14 days; mixed probe drugs were injected into rats by caudal vein. Through analyzing the pharmacokinetic parameter of mixed probe drugs in rats, we can calculate the CYPs activities. The results showed that RIF could inhibit CYP1A2 enzyme activity and induce CYP2C11 enzyme activity significantly. Interestingly, in realgar high dosage group, CYP3A1/2 enzyme activity was inhibited significantly, and different dosage of realgar manifested a good dose-dependent manner. The RIF results indicated that drug coadministrated with RIF may need to be paid attention in relation to drug-drug interactions (DDIs). Realgar, a toxic traditional Chinese medicine (TCM), does have curative effect on acute promyelocytic leukemia (APL). Its toxicity studies should be focused on. We found that, in realgar high dosage group, CYP3A1/2 enzymes activity was inhibited. This phenomenon may explain its potential toxicity mechanism. PMID:28421119

Influences of Realgar-Indigo naturalis, A Traditional Chinese Medicine Formula, on the Main CYP450 Activities in Rats Using a Cocktail Method.

PubMed

Xu, Huan-Hua; Hao, Fei-Ran; Wang, Mei-Xi; Ren, Si-Jia; Li, Ming; Tan, Hong-Ling; Wang, Yu-Guang; Tang, Xiang-Lin; Xiao, Cheng-Rong; Liang, Qian-De; Gao, Yue; Ma, Zeng-Chun

2017-01-01

The purpose of this work was to study the influences of Realgar- Indigo naturalis (RIF) and its principal element realgar on 4 main cytochrome P450 enzymes activities in rats. A simple and efficient cocktail method was developed to detect the four probe drugs simultaneously. In this study, Wistar rats were administered intragastric RIF and realgar for 14 days; mixed probe drugs were injected into rats by caudal vein. Through analyzing the pharmacokinetic parameter of mixed probe drugs in rats, we can calculate the CYPs activities. The results showed that RIF could inhibit CYP1A2 enzyme activity and induce CYP2C11 enzyme activity significantly. Interestingly, in realgar high dosage group, CYP3A1/2 enzyme activity was inhibited significantly, and different dosage of realgar manifested a good dose-dependent manner. The RIF results indicated that drug coadministrated with RIF may need to be paid attention in relation to drug-drug interactions (DDIs). Realgar, a toxic traditional Chinese medicine (TCM), does have curative effect on acute promyelocytic leukemia (APL). Its toxicity studies should be focused on. We found that, in realgar high dosage group, CYP3A1/2 enzymes activity was inhibited. This phenomenon may explain its potential toxicity mechanism.

Methyl-Deficient Diets and Risks of Breast Cancer Among African-American Women: A Case-Control Study by Methylation Status of the ER Gene

DTIC Science & Technology

1999-10-01

drug metabolism. The main cytochrome P450 enzymes that can mediate the metabolism of CAs include CYP3A4 , CYP 1 A2 and CYP2C.2124 Although African...Americans and whites have not been compared on CYP3A4 and CYP2C, CYP1A2 oxidative activity has been found to be lower in African Americans than in...These studies suggest that, although more evidence is needed on CYP3A4 and CYP2C, the CYP system is less effective in African-Americans than in whites.29

In vitro inhibitory activities of the extract of Hibiscus sabdariffa L. (family Malvaceae) on selected cytochrome P450 isoforms.

PubMed

Johnson, Showande Segun; Oyelola, Fakeye Titilayo; Ari, Tolonen; Juho, Hokkanen

2013-01-01

Literature is scanty on the interaction potential of Hibiscus sabdariffa L., plant extract with other drugs and the affected targets. This study was conducted to investigate the cytochrome P450 (CYP) isoforms that are inhibited by the extract of Hibiscus sabdariffa L. in vitro. The inhibition towards the major drug metabolizing CYP isoforms by the plant extract were estimated in human liver microsomal incubations, by monitoring the CYP-specific model reactions through previously validated N-in-one assay method. The ethanolic extract of Hibiscus sabdariffa showed inhibitory activities against nine selected CYP isoforms: CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP2E1 and CYP3A4. The concentrations of the extract which produced 50% inhibition of the CYP isoforms ranged from 306 µg/ml to 1660 µg/ml, and the degree of inhibition based on the IC50 values for each CYP isoform was in the following order: CYP1A2 > CYP2C8 > CYP2D6 > CYP2B6 > CYP2E1 > CYP2C19 > CYP3A4 > CYP2C9 > CYP2A6. Ethanolic extract of Hibiscus sabdariffa caused inhibition of CYP isoforms in vitro. These observed inhibitions may not cause clinically significant herb-drug interactions; however, caution may need to be taken in co-administering the water extract of Hibiscus sabdariffa with other drugs until clinical studies are available to further clarify these findings.

Evaluation of Pharmacokinetic Interactions Between Lesinurad, a New Selective Urate Reabsorption Inhibitor, and CYP Enzyme Substrates Sildenafil, Amlodipine, Tolbutamide, and Repaglinide.

PubMed

Gillen, Michael; Yang, Chun; Wilson, David; Valdez, Shakti; Lee, Caroline; Kerr, Bradley; Shen, Zancong

2017-07-01

Lesinurad is a selective uric acid reabsorption inhibitor approved for the treatment of hyperuricemia associated with gout in combination with xanthine oxidase inhibitors. In vitro assays indicate that lesinurad is an inducer of CYPs in the order CYP3A > CYP2C8 > CYP2C9 > CYP2C19 > CYP2B6 and an inhibitor of CYP2C8 and CYP2C9. To investigate the drug interaction potential of lesinurad, clinical drug interaction studies were conducted. Open-label studies in volunteers investigated the effects of single-/multiple-dose lesinurad on the pharmacokinetics of sildenafil and amlodipine (CYP3A4 induction), tolbutamide (CYP2C9 inhibition/induction), and repaglinide (CYP2C8 inhibition/induction). There was no apparent induction of CYP2C8 and CYP2C9 following repeated lesinurad administration, although no inhibition of CYP2C9 and modest inhibition of CYP2C8 were observed following single-dose lesinurad. Consistent with in vitro observations, lesinurad (200 mg once daily) was an inducer of CYP3A based on the effects on sildenafil exposure. Sildenafil exposure decreased by approximately 34% for C max and AUC when administered with multiple-dose lesinurad 200 mg and allopurinol 300 mg, relative to sildenafil alone. During lesinurad therapy, the possibility of reduced efficacy of concomitant drugs that are CYP3A substrates should be considered and their efficacy monitored because of induction of CYP3A by lesinurad. © 2017, The American College of Clinical Pharmacology.

The influence of CYP2B6, CYP2C9 and CYP2D6 genotypes on the formation of the potent antioestrogen Z-4-hydroxy-tamoxifen in human liver.

PubMed

Coller, Janet K; Krebsfaenger, Niels; Klein, Kathrin; Endrizzi, Karin; Wolbold, Renzo; Lang, Thomas; Nüssler, Andreas; Neuhaus, Peter; Zanger, Ulrich M; Eichelbaum, Michel; Mürdter, Thomas E

2002-08-01

To investigate in a large panel of 50 human liver samples the contribution of CYP2C9, CYP2D6, and CYP3A4 to the overall formation of the potent antioestrogen Z-4-hydroxy-tamoxifen, and how various genotypes affect its formation from tamoxifen. The formation of Z-4-hydroxy-tamoxifen from 10 microm tamoxifen was studied in human liver microsomes (n=50), characterized for CYP2B6, CYP2C9, CYP2D6 and CYP3A4 expression, and CYP2B6, CYP2C9 and CYP2D6 genotype. The effect of chemical and monoclonal antibody inhibitors, and the formation in supersomes expressing recombinant CYP isoforms was also investigated. Z-4-hydroxy-tamoxifen was quantified using LC-MS analysis. Z-4-hydroxy-tamoxifen was formed by supersomes expressing CYP2B6, CYP2C9, CYP2C19 and CYP2D6, but not CYP3A4. In agreement with these data, the mean formation of Z-4-hydroxy-tamoxifen was inhibited 49% by sulphaphenazole (P=0.001), 38% by quinidine (P<0.05) and 13% by monoclonal antibody against CYP2B6 (MAB-2B6, P<0.05). Furthermore, Z-4-hydroxy-tamoxifen formation significantly correlated with both CYP2C9 expression (r(s)=0.256, P<0.05) and CYP2D6 expression (r(s)=0.309, P<0.05). Genotypes of CYP2D6, CYP2B6 and CYP2C9 had an effect on metabolite formation in such a way that samples with two nonfunctional CYP2D6, or two variant CYP2C9 or CYP2B6 alleles, showed lower enzyme activity compared with those with two functional or wild-type alleles, (5.0 vs 9.9 pmol mg(-1) protein min(-1), P=0.046, 5.1 vs 9.9 pmol mg(-1) protein min(-1), P=0.053, and 6.8 vs 9.4 pmol mg(-1) protein min(-1), P=0.054, respectively). CYP2D6 and CYP2C9 contribute on average 45 and 46%, respectively, to the overall formation of Z-4-hydroxy-tamoxifen. CYP2B6, CYP2C9 and CYP2D6 genotypes all affected Z-4-hydroxy-tamoxifen formation and can predict individual ability to catalyse this reaction.

Fluoxetine and norfluoxetine mediated complex drug-drug interactions: in vitro to in vivo correlation of effects on CYP2D6, CYP2C19 and CYP3A4

PubMed Central

Sager, Jennifer E; Lutz, Justin D; Foti, Robert S; Davis, Connie; Kunze, Kent L; Isoherranen, Nina

2014-01-01

Fluoxetine and its circulating metabolite norfluoxetine present a complex multiple inhibitor system that causes reversible or time-dependent inhibition of CYP2D6, CYP3A4, and CYP2C19 in vitro. While significant inhibition of all three enzymes in vivo is predicted, midazolam and lovastatin AUCs were unaffected by two week dosing of fluoxetine whereas dextromethorphan AUC was increased by 27-fold and omeprazole AUC by 7.1-fold. This observed discrepancy between in vitro risk assessment and in vivo DDI profile was rationalized by time-varying dynamic pharmacokinetic models that incorporated circulating concentrations of fluoxetine and norfluoxetine enantiomers, mutual inhibitor-inhibitor interactions and CYP3A4 induction. The dynamic models predicted all DDIs with less than 2-fold error. This study demonstrates that complex drug-drug interactions that involve multiple mechanisms, pathways and inhibitors with their metabolites can be predicted and rationalized via characterization of all the inhibitory species in vitro. PMID:24569517

Application of the relative activity factor approach in scaling from heterologously expressed cytochromes p450 to human liver microsomes: studies on amitriptyline as a model substrate.

PubMed

Venkatakrishnan, K; von Moltke, L L; Greenblatt, D J

2001-04-01

The relative activity factor (RAF) approach is being increasingly used in the quantitative phenotyping of multienzyme drug biotransformations. Using lymphoblast-expressed cytochromes P450 (CYPs) and the tricyclic antidepressant amitriptyline as a model substrate, we have tested the hypothesis that the human liver microsomal rates of a biotransformation mediated by multiple CYP isoforms can be mathematically reconstructed from the rates of the biotransformation catalyzed by individual recombinant CYPs using the RAF approach, and that the RAF approach can be used for the in vitro-in vivo scaling of pharmacokinetic clearance from in vitro intrinsic clearance measurements in heterologous expression systems. In addition, we have compared the results of two widely used methods of quantitative reaction phenotyping, namely, chemical inhibition studies and the prediction of relative contributions of individual CYP isoforms using the RAF approach. For the pathways of N-demethylation (mediated by CYPs 1A2, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4) and E-10 hydroxylation (mediated by CYPs 2B6, 2D6, and 3A4), the model-predicted biotransformation rates in microsomes from a panel of 12 human livers determined from enzyme kinetic parameters of the recombinant CYPs were similar to, and correlated with the observed rates. The model-predicted clearance via N-demethylation was 53% lower than the previously reported in vivo pharmacokinetic estimates. Model-predicted relative contributions of individual CYP isoforms to the net biotransformation rate were similar to, and correlated with the fractional decrement in human liver microsomal reaction rates by chemical inhibitors of the respective CYPs, provided the chemical inhibitors used were specific to their target CYP isoforms.

Cytochrome p450 2E1 polymorphisms and the risk of gastric cardia cancer

PubMed Central

Cai, Lin; Zheng, Zong-Li; Zhang, Zuo-Feng

2005-01-01

AIM: Genetic polymorphisms of drug-metabolizing enzymes have recently been shown to affect susceptibility to chemical carcinogenesis. Cytochrome P450 2E1 (CYP2E1) enzyme catalyzes the metabolism of many procarcinogens, such as N-nitrosamines and related compounds. The gene coding for this enzyme is polymorphic and thus may play a role in gastric cardia cancer (GCC) etiology. In this hospital-based case-control study, we evaluate the relationship between genetic polymorphisms of CYP2E1 and the risk of GCC. METHODS: The study subjects comprised 159 histologically confirmed GCC cases identified via hospital cancer registry and surgical records at five hospitals in Fuzhou, Fujian Province, China, between April and November 2001. Controls were 192 patients admitted to the same hospitals for nonmalignant conditions. The genotypes of CYP2E1 were detected by a PCR-based RFLP assay. The odds ratios were estimated by logistic regression analyses and were adjusted for potential confounding factors. RESULTS: The distribution of three genotypes of CYP2E1 in GCC cases and controls was significantly different (χ2 = 16.04, P<0.01). The frequency of the CYP2E1 (c1/c1) genotype in GCC cases and controls was 60.4% and 40.1%, respectively. The CYP2E1 (c1/c1) genotype was associated with an increased risk for GCC (the adjusted (OR) was 2.37, 95% confidence interval (CI): 1.52-3.70). Subjects who carried the CYP2E1 (c1/c1) genotype and were habitual smokers were at a significantly higher risk of developing GCC (OR = 4.68, 95%CI: 2.19-10.04) compared with those who had the CYP2E1 (c1/c2 or c2/c2) genotype and did not smoke. CONCLUSION: These results suggest that the CYP2E1 genotype may influence individual susceptibility to development of GCC, and that the risk increases significantly in smokers. PMID:15793883

The effect of milk thistle (Silybum marianum) and its main flavonolignans on CYP2C8 enzyme activity in human liver microsomes.

PubMed

Albassam, Ahmed A; Frye, Reginald F; Markowitz, John S

2017-06-01

Milk thistle is a widely-consumed botanical used for an array of purported health benefits. The primary extract of milk thistle is termed silymarin, a complex mixture that contains a number of structurally-related flavonolignans, the flavonoid, taxifolin, and a number of other constituents. The major flavonolignans present in most extracts are silybin A, silybin B, isosilybin A and isosilybin B, silydianin, silychristin and isosilychristin. Silymarin itself has been reported to inhibit CYP2C8 activity in vitro, but the effect of the individual flavonolignans on this enzyme has not been studied. To investigate the effects of milk thistle extract and its main flavonolignans (silybin A, silybin B, isosilybin A and isosilybin B) on CYP2C8 activity at relevant concentrations, the effect of milk thistle extract and the flavonolignans on CYP2C8 enzyme activity was studied in vitro using human liver microsomes (HLM) incorporating an enzyme-selective substrate for CYP2C8, amodiaquine. Metabolite formation was analyzed using liquid chromatography-tandem mass spectrometry (LC/MS-MS). The concentration causing 50% inhibition of enzyme activity (IC 50 ) was used to express the degree of inhibition. Isosilibinin, a mixture of the diastereoisomers isosilybin A and isosilybin B, was found to be the most potent inhibitor, followed by isosilybin B with IC 50 values (mean ± SE) of 1.64 ± 0.66 μg/mL and 2.67 ± 1.18 μg/mL, respectively. The rank order of observed inhibitory potency after isosilibinin was silibinin > isosilybin A > silybin A > milk thistle extract > and silybin B. These in vitro results suggest a potentially significant inhibitory effect of isosilibinin and isosilybin B on CYP2C8 activity. However, the observed IC 50 values are unlikely to be achieved in humans supplemented with orally administered milk thistle extracts due to the poor bioavailability of flavonolignans documented with most commercially available formulations. Copyright © 2017 Elsevier B.V. All rights reserved.

Associations of CYP3A4, NR1I2, CYP2C19 and P2RY12 polymorphisms with clopidogrel resistance in Chinese patients with ischemic stroke

PubMed Central

Liu, Rui; Zhou, Zi-yi; Chen, Yi-bei; Li, Jia-li; Yu, Wei-bang; Chen, Xin-meng; Zhao, Min; Zhao, Yuan-qi; Cai, Ye-feng; Jin, Jing; Huang, Min

2016-01-01

Aim: There is a high incidence of the antiplatelet drug clopidogrel resistance (CR) in Asian populations. Because clopidogrel is a prodrug, polymorphisms of genes encoding the enzymes involved in its biotransformation may be the primary influential factors. The goal of this study was to investigate the associations of polymorphisms of CYP3A4, NR1I2, CYP2C19 and P2RY12 genes with CR in Chinese patients with ischemic stroke. Methods: A total of 191 patients with ischemic stroke were enrolled. The patients were treated with clopidogrel for at least 5 days. Platelet function was measured by light transmission aggregometry. The SNPs NR1I2 (rs13059232), CYP3A4*1G (rs2242480), CYP2C19*2 (rs4244285) and P2RY12 (rs2046934) were genotyped. Results: The CR rate in this population was 36%. The CYP2C19*2 variant was a risk factor for CR (*2/*2+wt/*2 vs wt/wt, OR: 2.366, 95% CI: 1.180–4.741, P=0.014), whereas the CYP3A4*1G variant had a protective effect on CR (*1/*1 vs *1G/*1G+*1/*1G, OR: 2.360, 95% CI: 1.247–4.468, P=0.008). The NR1I2 (rs13059232) polymorphism was moderately associated with CR (CC vs TT+TC, OR: 0.533, 95% CI: 0.286–0.991, P=0.046). The C allele in P2RY12 (rs2046934) was predicted to be a protective factor for CR (CC+TC vs TT, OR: 0.407, 95% CI: 0.191–0.867, P=0.018). In addition, an association was found between hypertension and CR (P=0.022). Conclusion: The individuals with both the CYP2C19*2 allele and hypertension are at high risk of CR during anti-thrombosis therapy. The CYP3A4*1G allele, P2RY12 (rs2046934) C allele and NR1I2 (rs13059232) CC genotype may be protective factors for CR. The associated SNPs studied may be useful to predict clopidogrel resistance in Chinese patients with ischemic stroke. PMID:27133299

Venetoclax (ABT-199) Might Act as a Perpetrator in Pharmacokinetic Drug-Drug Interactions.

PubMed

Weiss, Johanna; Gajek, Thomas; Köhler, Bruno Christian; Haefeli, Walter Emil

2016-02-24

Venetoclax (ABT-199) represents a specific B-cell lymphoma 2 (Bcl-2) inhibitor that is currently under development for the treatment of lymphoid malignancies. So far, there is no published information on its interaction potential with important drug metabolizing enzymes and drug transporters, or its efficacy in multidrug resistant (MDR) cells. We therefore scrutinized its drug-drug interaction potential in vitro. Inhibition of cytochrome P450 enzymes (CYPs) was quantified by commercial kits. Inhibition of drug transporters (P-glycoprotein (P-gp, ABCB1), breast cancer resistance protein (BCRP), and organic anion transporting polypeptides (OATPs)) was evaluated by the use of fluorescent probe substrates. Induction of drug transporters and drug metabolizing enzymes was quantified by real-time RT-PCR. The efficacy of venetoclax in MDR cells lines was evaluated with proliferation assays. Venetoclax moderately inhibited P-gp, BCRP, OATP1B1, OATP1B3, CYP3A4, and CYP2C19, whereas CYP2B6 activity was increased. Venetoclax induced the mRNA expression of CYP1A1, CYP1A2, UGT1A3, and UGT1A9. In contrast, expression of ABCB1 was suppressed, which might revert tumor resistance towards antineoplastic P-gp substrates. P-gp over-expression led to reduced antiproliferative effects of venetoclax. Effective concentrations for inhibition and induction lay in the range of maximum plasma concentrations of venetoclax, indicating that it might act as a perpetrator drug in pharmacokinetic drug-drug interactions.

Venetoclax (ABT-199) Might Act as a Perpetrator in Pharmacokinetic Drug–Drug Interactions

PubMed Central

Weiss, Johanna; Gajek, Thomas; Köhler, Bruno Christian; Haefeli, Walter Emil

2016-01-01

Venetoclax (ABT-199) represents a specific B-cell lymphoma 2 (Bcl-2) inhibitor that is currently under development for the treatment of lymphoid malignancies. So far, there is no published information on its interaction potential with important drug metabolizing enzymes and drug transporters, or its efficacy in multidrug resistant (MDR) cells. We therefore scrutinized its drug–drug interaction potential in vitro. Inhibition of cytochrome P450 enzymes (CYPs) was quantified by commercial kits. Inhibition of drug transporters (P-glycoprotein (P-gp, ABCB1), breast cancer resistance protein (BCRP), and organic anion transporting polypeptides (OATPs)) was evaluated by the use of fluorescent probe substrates. Induction of drug transporters and drug metabolizing enzymes was quantified by real-time RT-PCR. The efficacy of venetoclax in MDR cells lines was evaluated with proliferation assays. Venetoclax moderately inhibited P-gp, BCRP, OATP1B1, OATP1B3, CYP3A4, and CYP2C19, whereas CYP2B6 activity was increased. Venetoclax induced the mRNA expression of CYP1A1, CYP1A2, UGT1A3, and UGT1A9. In contrast, expression of ABCB1 was suppressed, which might revert tumor resistance towards antineoplastic P-gp substrates. P-gp over-expression led to reduced antiproliferative effects of venetoclax. Effective concentrations for inhibition and induction lay in the range of maximum plasma concentrations of venetoclax, indicating that it might act as a perpetrator drug in pharmacokinetic drug–drug interactions. PMID:26927160

Evaluation of the in vitro and in vivo metabolic pathway and cytochrome P450 inhibition/induction profile of Huperzine A.

PubMed

Lin, Ping-Ping; Li, Xue-Ning; Yuan, Fei; Chen, Wei-Li; Yang, Meng-Jie; Xu, Hong-Rong

2016-11-11

Huperzine A (HupA), one of the reversible and selective acetylcholinesterase inhibitors derived from Chinese herb Huperzia Serrata, possesses affirmative action of ameliorating cognitive dysfunction of Alzheimer's disease. Up to now, the effects of HupA on human cytochrome P450s (CYPs) have not been fully elucidated. The purpose of the present study was to clarify the metabolic pathway of HupA in vitro and in vivo, and to evaluate the CYPs inhibition/induction profile of HupA in vitro. The catalytic activity of CYP enzymes (CYP1A2, 2A6, 2C9, 2C19, 2D6, 2E1 and 3A4) was measured by the quantification of specific enzyme substrates using validated liquid chromatography-tandem mass spectrometry (LC/MS/MS) methods. The in vivo metabolic pathway evaluation was performed in an open, single-dose pharmacokinetic study of HupA in fourteen elderly subjects, with urine collecting at certain intervals. In human liver microsomes, HupA (10 ng/mL) was not metabolized within 90 min, and it showed negligible inhibition against these CYP isoforms within 0.2-100 ng/mL. In human liver hepatocytes, the activities of CYP1A2 and CYP3A4 were not significantly altered when incubated at 2 or 20 ng/mL of HupA. After oral administration of 0.1 mg HupA, the total proportion of HupA excreted through urine was relatively high, accounting to 35± 9% at the limited time period of 48 h. These results suggest that HupA is substantially excreted by kidney unchanged rather than metabolized by human liver, and is unlikely to cause clinically relevant drug-drug interaction (DDI) when co-administrated with drugs that are metabolized by CYP isoenzyme system. Copyright © 2016 Elsevier Inc. All rights reserved.

Physician Response to Implementation of Genotype-Tailored Antiplatelet Therapy

PubMed Central

Peterson, Josh F.; Field, Julie R.; Unertl, Kim; Schildcrout, Jonathan S.; Johnson, Daniel C.; Shi, Yaping; Danciu, Ioana; Cleator, John H.; Pulley, Jill M.; McPherson, John A.; Denny, Josh C.; Laposata, Michael; Roden, Dan M.; Johnson, Kevin B.

2016-01-01

Physician responses to genomic information are vital to the success of precision medicine initiatives. We prospectively studied a pharmacogenomics implementation program for the propensity of clinicians to select antiplatelet therapy based on CYP2C19 loss-of-function (LOF) variants in stented patients. Among 2,676 patients, 514 (19.2%) were found to have a CYP2C19 variant affecting clopidogrel metabolism. For the majority (93.6%) of the cohort, cardiologists received active and direct notification of CYP2C19 status. Over 12 months, 57.6% of poor metabolizers and 33.2% of intermediate metabolizers received alternatives to clopidogrel. CYP2C19 variant status was the most influential factor impacting the prescribing decision [HR in poor metabolizers 8.1, 95% CI (5.4,12.2) and HR 5.0, 95% CI (4.0,6.3) in intermediate metabolizers], followed by patient age and type of stent implanted. We conclude that cardiologists tailored antiplatelet therapy for a minority of patients with a CYP2C19 variant and considered both genomic and non-genomic risks in their clinical decision-making. PMID:26693963

Seasonal changes in the activity of cytochrome P450(C17) from the testis of Bufo arenarum.

PubMed

Solari, J J F; Pozzi, A G; Ceballos, N R

2002-12-01

In Bufo arenarum, the biosynthesis of testosterone and 5alpha-dihydrotestosterone takes place through a complete 5-ene pathway, 5-androsten-3beta,17beta-diol being the immediate precursor of testosterone. Besides androgens, testes are able to synthesise 5alpha-pregnan-3,20-dione and several 3alpha and 20alpha reduced derivatives. During the breeding season, steroid biosynthesis turns from androgen to C21-steroid production. As a consequence, the cytochrome P450 17-hydroxylase, C17,20-lyase (CypP450(c17)) could be a key enzyme in that metabolic shift. The present study demonstrates that in testes of B. arenarum, CypP450(c17) co-localises with glucose-6-phosphatase in the microsomal fraction. CypP450(c17) possesses more affinity for pregnenolone than for progesterone in both non-reproductive (Km = 43.76 +/- 4.63 nM and 2,170 +/- 630 nM, respectively) and reproductive (Km = 37.46 +/- 4.19 nM and 3,060 +/- 190 nM, respectively) seasons. These results could explain the predominance of the 5-ene pathway for testosterone biosynthesis. Toad CypP450(c17) activity is higher in the non-reproductive period than the reproductive period, suggesting that this enzyme is an important factor in toad steroidogenic changes. Animals in reproductive conditions showed a significant reduction in circulating androgens. This is in agreement with the decrease in Vmax of cytochrome P450 17-hydroxylase activity, enhancing the physiological relevance of these in vitro results.

CYP2C9 and CYP2C19 genetic polymorphisms: frequencies in the south Indian population.

PubMed

Jose, Rosemary; Chandrasekaran, Adithan; Sam, Soya Sisy; Gerard, Nathalie; Chanolean, Shashindran; Abraham, Benny K; Satyanarayanamoorthy, K; Peter, Anitha; Rajagopal, Krishnamoorthy

2005-02-01

The aim of the study was to establish the frequencies of CYP2C9*1, *2, *3 and CYP2C19*1, *2 and *3 in the south Indian population and to compare them with the inter-racial distribution of the CYP2C9 and CYP2C19 genetic polymorphisms. Genotyping analyses of CYP2C9 and CYP2C19 were conducted in unrelated, healthy volunteers from the three south Indian states of Andhra Pradesh, Karnataka and Kerala, by the polymerase chain reaction-restriction fragment-length polymorphism (PCR-RFLP). The allele frequencies of the populations of these three states were then pooled with our previous genotyping data of Tamilians (also in south India), to arrive at the distribution of CYP2C9 and CYP2C19 alleles in the south Indian population. Frequencies of CYP2C9 and CYP2C19 alleles and genotypes among various populations were compared using the two-tailed Fisher's exact test. The frequencies of CYP2C9*1, *2 and *3 in the south Indian population were 0.88 (95% CI 0.85-0.91), 0.04 (95% CI 0.02-0.06) and 0.08 (95% CI 0.06-0.11), respectively. The frequencies of CYP2C9 genotypes *1/*1, *1/*2, *1/*3, *2/*2, *2/*3 and *3/*3 were 0.78 (95% CI 0.74-0.82), 0.05 (95% CI 0.03-0.07), 0.15 (95% CI 0.12-0.18), 0.01 (95% CI 0.0-0.02), 0.01 (95% CI 0.0-0.02) and 0.0, respectively. CYP2C19*1, *2 and *3 frequencies were 0.64 (95% CI 0.60-0.68), 0.35 (95% CI 0.31-0.39) and 0.01 (95% CI 0.0-0.03), respectively. As a result of a significant heterogeneity, the data on CYP2C19 genotype frequencies were not pooled. The frequency of CYP2C9*2 mutant alleles in south Indians was higher than in Chinese and Caucasians, while CYP2C9*3 was similar to Caucasians. CYP2C19*2 was higher than in other major populations reported so far. The relatively high CYP2C19 poor-metabolizer genotype frequency of 12.6% indicates that over 28 million south Indians are poor metabolizers of CYP2C19 substrates.

Association of Cytochrome P450 2C19 Genotype With the Antiplatelet Effect and Clinical Efficacy of Clopidogrel Therapy

PubMed Central

Shuldiner, Alan R.; O'Connell, Jeffrey R.; Bliden, Kevin P.; Gandhi, Amish; Ryan, Kathleen; Horenstein, Richard B.; Damcott, Coleen M.; Pakyz, Ruth; Tantry, Udaya S.; Gibson, Quince; Pollin, Toni I.; Post, Wendy; Parsa, Afshin; Mitchell, Braxton D.; Faraday, Nauder; Herzog, William; Gurbel, Paul A.

2013-01-01

Context Clopidogrel therapy improves cardiovascular outcomes in patients with acute coronary syndromes and following percutaneous coronary intervention by inhibiting adenosine diphosphate (ADP)–dependent platelet activation. However, nonresponsiveness is widely recognized and is related to recurrent ischemic events. Objective To identify gene variants that influence clopidogrel response. Design, Setting, and Participants In the Pharmacogenomics of Antiplatelet Intervention (PAPI) Study (2006-2008), we administered clopidogrel for 7 days to 429 healthy Amish persons and measured response by ex vivo platelet aggregometry. A genome-wide association study was performed followed by genotyping the loss-of-function cytochrome P450 (CYP) 2C19*2 variant (rs4244285). Findings in the PAPI Study were extended by examining the relation of CYP2C19*2 genotype to platelet function and cardiovascular outcomes in an independent sample of 227 patients undergoing percutaneous coronary intervention. Main Outcome Measure ADP-stimulated platelet aggregation in response to clopidogrel treatment and cardiovascular events. Results Platelet response to clopidogrel was highly heritable (h2=0.73; P<.001). Thirteen single-nucleotide polymorphisms on chromosome 10q24 within the CYP2C18-CYP2C19-CYP2C9-CYP2C8 cluster were associated with diminished clopidogrel response, with a high degree of statistical significance (P=1.5 × 10−13 for rs12777823, additive model). The rs12777823 polymorphism was in strong linkage disequilibrium with the CYP2C19*2 variant, and was associated with diminished clopidogrel response, accounting for 12% of the variation in platelet aggregation to ADP (P=4.3 × 10−11). The relation between CYP2C19*2 genotype and platelet aggregation was replicated in clopidogrel-treated patients undergoing coronary intervention (P=.02). Furthermore, patients with the CYP2C19*2 variant were more likely (20.9% vs 10.0%) to have a cardiovascular ischemic event or death during 1 year of follow-up (hazard ratio, 2.42; 95% confidence interval, 1.18-4.99; P=.02). Conclusion CYP2C19*2 genotype was associated with diminished platelet response to clopidogrel treatment and poorer cardiovascular outcomes. PMID:19706858

Delayed de-induction of CYP2C9 compared to CYP3A after discontinuation of rifampicin: Report of two cases
.

PubMed

Shibata, Soichi; Takahashi, Harumi; Baba, Akiyasu; Takeshita, Kei; Atsuda, Koichiro; Matsubara, Hajime; Echizen, Hirotoshi

2017-05-01

Timely dose reduction of concomitant medications is important after withdrawal of rifampicin, a CYP inducer. However, little is known about the differences in the time course of deinduction for various CYP isoforms. To clarify the time courses of deinduction of CYP2C9 and -CYP3A activities after rifampicin withdrawal, we monitored these enzyme activities in 2 patients over time after discontinuing rifampicin. Two patients (aged 70 and 80 years) received warfarin and rifampicin for anticoagulation and antituberculosis therapy, respectively. Warfarin doses were increased due to rifampicin-induced CYP activity. Upon completion of antituberculosis therapy, rifampicin was discontinued and warfarin doses were titrated downward according to prothrombin time. We monitored CYP2C9 and CYP3A activities over their clinical courses by measuring the metabolic clearance of S-warfarin to S-7-hydroxywarfarin and that of cortisol to 6β-hydroxycortisol, respectively. In both patients, the time courses of CYP2C9 deinduction appeared to be delayed compared to CYP3A. Our findings suggest that a uniform dose reduction protocol for drugs metabolized by different CYP isoforms may be unsafe after rifampicin withdrawal.
.

Biotechnological Production of Caffeic Acid by Bacterial Cytochrome P450 CYP199A2

PubMed Central

Arai, Yuka; Kino, Kuniki

2012-01-01

Caffeic acid is a biologically active molecule that has various beneficial properties, including antioxidant, anticancer, and anti-inflammatory activities. In this study, we explored the catalytic potential of a bacterial cytochrome P450, CYP199A2, for the biotechnological production of caffeic acid. When the CYP199A2 enzyme was reacted with p-coumaric acid, it stoichiometrically produced caffeic acid. The crystal structure of CYP199A2 shows that Phe at position 185 is situated directly above, and only 6.35 Å from, the heme iron. This F185 residue was replaced with hydrophobic or hydroxylated amino acids using site-directed mutagenesis to create mutants with novel and improved catalytic properties. In whole-cell assays with the known substrate of CYP199A2, 2-naphthoic acid, only the wild-type enzyme hydroxylated 2-naphthoic acid at the C-7 and C-8 positions, whereas all of the active F185 mutants exhibited a preference for C-5 hydroxylation. Interestingly, several F185 mutants (F185V, F185L, F185I, F185G, and F185A mutants) also acquired the ability to hydroxylate cinnamic acid, which was not hydroxylated by the wild-type enzyme. These results demonstrate that F185 is an important residue that controls the regioselectivity and the substrate specificity of CYP199A2. Furthermore, Escherichia coli cells expressing the F185L mutant exhibited 5.5 times higher hydroxylation activity for p-coumaric acid than those expressing the wild-type enzyme. By using the F185L whole-cell catalyst, the production of caffeic acid reached 15 mM (2.8 g/liter), which is the highest level so far attained in biotechnological production of this compound. PMID:22729547

Herbal medicine yin zhi huang induces CYP3A4-mediated sulfoxidation and CYP2C19-dependent hydroxylation of omeprazole.

PubMed

Fan, Lan; Wang, Guo; Wang, Lian-Sheng; Chen, Yao; Zhang, Wei; Huang, Yuan-Fei; Huang, Rui-Xue; Hu, Dong-Li; Wang, Dan; Zhou, Hong-Hao

2007-10-01

To explore the potential interactions between yin zhi huang (YZH) and omeprazole, a substrate of CYP3A4 and CYP2C19. Eighteen healthy volunteers, including 6 CYP2C19*1/*1, 6 CYP2C19*1/*2 or *3 and 6 CYP2C19*2/*2 were enrolled in a 2-phase, randomized, crossover clinical trial. In each phase, the volunteers received either placebo or 10 mL YZH oral liquid, 3 times daily for 14 d. Then all the patients took a 20 mg omeprazole capsule orally. Blood samples were collected up to 12 h after omeprazole administration. Plasma concentrations of omeprazole and its metabolites were quantified by HPLC with UV detection. After 14 d of treatment of YZH, plasma omeprazole significantly decreased and those of omeprazole sulfone and 5-hydroxyomeprazole significantly increased. The ratios of the area under the plasma concentration-time curves from time 0 to infinity (AUC(0-infinity) of omeprazole to 5-hydroxyomprazole and those of omeprazole to omeprazole sulfone decreased by 64.80%+/-12.51% (P=0.001) and 63.31%+/-18.45% (P=0.004) in CYP2C19*1/*1, 57.98%+/-14.80% (P=0.002) and 54.87%+/-18.42% (P=0.003) in CYP2C19*1/*2 or *3, and 37.74%+/-16.07% (P=0.004) and 45.16%+/-15.54% (P=0.003) in CYP2C19*2/*2, respectively. The decrease of the AUC(0-infinity) ratio of omeprazole to 5-hydroxyomprazole in CYP2C19*1/*1 and CYP2C19*1/*2 or *3 was greater than those in CYP2C19*2/*2 (P=0.047 and P=0.009). YZH induces both CYP3A4-catalyzed sulfoxidation and CYP2C19-dependent hydroxylation of omeprazole leading to decreases in plasma omeprazole concentrations.

Association of CYP2C19*2 and *3 Genetic Variants with Essential Hypertension in Koreans

PubMed Central

Shin, Dong-Jik; Kwon, Jisun; Park, Ah-Ram; Bae, Yousun; Shin, Eun-Soon; Park, Sungha

2012-01-01

Purpose The cytochrome P450 2C19 (CYP2C19) metabolizes arachidonic acid to produce epoxyicosanoid acids, which are involved in vascular tone and regulation of blood pressure. Recent findings suggest that CYP2C19 gene might be considered as a novel candidate gene for treatment of cardiovascular disease. The aim of the present study was to evaluate the association between two variants, CYP2C19*2 (681G>A) and CYP2C19*3 (636G>A) and the development of essential hypertension (EH) in Koreans. Materials and Methods We carried out an association study in a total of 1190 individuals (527 hypertensive subjects and 663 unrelated healthy controls). The CYP2C19 polymorphisms were genotyped using the SNaPShot™ assay. Results The distribution of alleles and genotypes of CYP2C19*3 showed significant difference between hypertensive patients and normal controls (p=0.011 and p=0.013, respectively). Logistic regression analysis indicated that the CYP2C19*3 (636A) allele carriers were significantly associated with EH [odds ratio, 0.691; 95% confidence interval (CI), 0.512-0.932, p=0.016], in comparison to wild type homozygotes (CYP2C19*1/*1). Neither genotype nor allele distribution of CYP2C19*2 polymorphism showed significant differences between hypertensive and control groups (p>0.05). Conclusion Our present findings strengthen the evidence of an association between CYP2C19 gene polymorphism and EH prevalence. In particular, the CYP2C19*3 defective allele may contribute to reduced risk for the development of EH. PMID:23074110

Are there differences in the catalytic activity per unit enzyme of recombinantly expressed and human liver microsomal cytochrome P450 2C9? A systematic investigation into inter-system extrapolation factors.

PubMed

Crewe, H K; Barter, Z E; Yeo, K Rowland; Rostami-Hodjegan, A

2011-09-01

The 'relative activity factor' (RAF) compares the activity per unit of microsomal protein in recombinantly expressed cytochrome P450 enzymes (rhCYP) and human liver without separating the potential sources of variation (i.e. abundance of enzyme per mg of protein or variation of activity per unit enzyme). The dimensionless 'inter-system extrapolation factor' (ISEF) dissects differences in activity from those in CYP abundance. Detailed protocols for the determination of this scalar, which is used in population in vitro-in vivo extrapolation (IVIVE), are currently lacking. The present study determined an ISEF for CYP2C9 and, for the first time, systematically evaluated the effects of probe substrate, cytochrome b5 and methods for assessing the intrinsic clearance (CL(int) ). Values of ISEF for S-warfarin, tolbutamide and diclofenac were 0.75 ± 0.18, 0.57 ± 0.07 and 0.37 ± 0.07, respectively, using CL(int) values derived from the kinetic values V(max) and K(m) of metabolite formation in rhCYP2C9 + reductase + b5 BD Supersomes™. The ISEF values obtained using rhCYP2C9 + reductase BD Supersomes™ were more variable, with values of 7.16 ± 1.25, 0.89 ± 0.52 and 0.50 ± 0.05 for S-warfarin, tolbutamide and diclofenac, respectively. Although the ISEF values obtained from rhCYP2C9 + reductase + b5 for the three probe substrates were statistically different (p < 0.001), the use of the mean value of 0.54 resulted in predicted oral clearance values for all three substrates within 1.4 fold of the observed literature values. For consistency in the relative activity across substrates, use of a b5 expressing recombinant system, with the intrinsic clearance calculated from full kinetic data is recommended for generation of the CYP2C9 ISEF. Furthermore, as ISEFs have been found to be sensitive to differences in accessory proteins, rhCYP system specific ISEFs are recommended. Copyright © 2011 John Wiley & Sons, Ltd.

Alteration of the Expression of Pesticide-Metabolizing Enzymes in Pregnant Mice: Potential Role in the Increased Vulnerability of the Developing Brain

PubMed Central

Fortin, Marie C.; Aleksunes, Lauren M.

2013-01-01

Studies on therapeutic drug disposition in humans have shown significant alterations as the result of pregnancy. However, it is not known whether pesticide metabolic capacity changes throughout pregnancy, which could affect exposure of the developing brain. We sought to determine the effect of pregnancy on the expression of hepatic enzymes involved in the metabolism of pesticides. Livers were collected from virgin and pregnant C57BL/6 mice at gestational days (GD)7, GD11, GD14, GD17, and postpartum days (PD)1, PD15, and PD30. Relative mRNA expression of several enzymes involved in the metabolism of pesticides, including hepatic cytochromes (Cyp) P450s, carboxylesterases (Ces), and paraoxonase 1 (Pon1), were assessed in mice during gestation and the postpartum period. Compared with virgin mice, alterations in the expression occurred at multiple time points, with the largest changes observed on GD14. At this time point, the expression of most of the Cyps involved in pesticide metabolism in the liver (Cyp1a2, Cyp2d22, Cyp2c37, Cyp2c50, Cyp2c54, and Cyp3a11) were downregulated by 30% or more. Expression of various Ces isoforms and Pon1 were also decreased along with Pon1 activity. These data demonstrate significant alterations in the expression of key enzymes that detoxify pesticides during pregnancy, which could alter exposure of developing animals to these chemicals. PMID:23223497

Cytochrome P450-mediated hepatic metabolism of new fluorescent substrates in cats and dogs.

PubMed

van Beusekom, C D; Schipper, L; Fink-Gremmels, J

2010-12-01

This study aimed to investigate the biotransformation of cat liver microsomes in comparison to dogs and humans using a high throughput method with fluorescent substrates and classical inhibitors specific for certain isozymes of the human cytochrome P450 (CYP) enzyme family. The metabolic activities associated with CYP1A, CYP2B, CYP2C, CYP2D, CYP2E and CYP3A were measured. Cat liver microsomes metabolized all substrates selected for the assessment of cytochrome P450 activity. The activities associated with CYP3A and CYP2B were higher than the activities of the other measured CYPs. Substrate selectivity could be demonstrated by inhibition studies with α-naphthoflavone (CYP1A), tranylcypromine/quercetine (CYP2C), quinidine (CYP2D), diethyldithiocarbamic acid (CYP2E) and ketoconazole (CYP3A) respectively. Other prototypical inhibitors used for characterization of human CYP activities such as furafylline (CYP1A), tranylcypromine (CYP2B) and sulfaphenazole (CYP2C) did not show significant effects in cat and dog liver microsomes. Moreover, IC50-values of cat CYPs differed from dog and human CYPs underlining the interspecies differences. Gender differences were observed in the oxidation of 7-ethoxy-4-trifluoromethylcoumarin (CYP2B) and 3-[2-(N, N-diethyl-N-methylamino)ethyl]-7-methoxy-4-methylcoumarin (CYP2D), which were significantly higher in male cats than in females. Conversely, oxidation of the substrates dibenzylfluorescein (CYP2C) and 7-methoxy-4-trifluoromethylcoumarin (CYP2E) showed significant higher activities in females than in male cats. Overall CYP-activities in cat liver microsomes were lower than in those from dogs or humans, except for CYP2B. The presented difference between feline and canine CYP-activities are useful to establish dose corrections for feline patients of intensively metabolized drugs licensed for dogs or humans. © 2010 Blackwell Publishing Ltd.

CYP2C9 Genotype-Dependent Warfarin Pharmacokinetics: Impact of CYP2C9 Genotype on R- and S-Warfarin and Their Oxidative Metabolites.

PubMed

Flora, Darcy R; Rettie, Allan E; Brundage, Richard C; Tracy, Timothy S

2017-03-01

Multiple factors can impact warfarin therapy, including genetic variations in the drug-metabolizing enzyme cytochrome P450 2C9 (CYP2C9). Compared with individuals with the wild-type allele, CYP2C9*1, carriers of the common *3 variant have significantly impaired CYP2C9 metabolism. Genetic variations in CYP2C9, the primary enzyme governing the metabolic clearance of the more potent S-enantiomer of the racemic anticoagulant warfarin, may impact warfarin-drug interactions. To establish a baseline for such studies, plasma and urine concentrations of R- and S-warfarin and 10 warfarin metabolites were monitored for up to 360 hours following a 10-mg warfarin dose in healthy subjects with 4 different CYP2C9 genotypes: CYP2C9*1/*1 (n = 8), CYP2C9*1/*3 (n = 9), CYP2C9*2/*3 (n = 3), and CYP2C9*3/*3 (n = 4). Plasma clearance of S-warfarin, but not R-warfarin, decreased multiexponentially and in a CYP2C9 gene-dependent manner: 56%, 70%, and 75% for CYP2C9*1/*3, CYP2C9*2/*3, and CYP2C9*3/*3 genotypes, respectively, compared with CYP2C9*1/*1, resulting in pronounced differences in the S:R ratio that identified warfarin-sensitive genotypes. CYP2C9 was the primary P450 enzyme contributing to S-warfarin metabolism and a minor contributor to R-warfarin metabolism. In the presence of a defective CYP2C9 allele, switching of warfarin metabolism to other oxidative pathways and P450 enzymes for the metabolic elimination of S-warfarin was not observed. The 10-hydroxywarfarin metabolites, whose detailed pharmacokinetics are reported for the first time, exhibited a prolonged half-life with no evidence of renal excretion and displayed elimination rate-limited kinetics. Understanding the impact of CYP2C9 genetics on warfarin pharmacokinetics lays the foundation for future genotype-dependent warfarin-drug interaction studies. © 2016, The American College of Clinical Pharmacology.

CYP77A19 and CYP77A20 characterized from Solanum tuberosum oxidize fatty acids in vitro and partially restore the wild phenotype in an Arabidopsis thaliana cutin mutant.

PubMed

Grausem, B; Widemann, E; Verdier, G; Nosbüsch, D; Aubert, Y; Beisson, F; Schreiber, L; Franke, R; Pinot, F

2014-09-01

Cutin and suberin represent lipophilic polymers forming plant/environment interfaces in leaves and roots. Despite recent progress in Arabidopsis, there is still a lack on information concerning cutin and suberin synthesis, especially in crops. Based on sequence homology, we isolated two cDNA clones of new cytochrome P450s, CYP77A19 and CYP77A20 from potato tubers (Solanum tuberosum). Both enzymes hydroxylated lauric acid (C12:0) on position ω-1 to ω-5. They oxidized fatty acids with chain length ranging from C12 to C18 and catalysed hydroxylation of 16-hydroxypalmitic acid leading to dihydroxypalmitic (DHP) acids, the major C16 cutin and suberin monomers. CYP77A19 also produced epoxides from linoleic acid (C18:2). Exploration of expression pattern in potato by RT-qPCR revealed the presence of transcripts in all tissues tested with the highest expression in the seed compared with leaves. Water stress enhanced their expression level in roots but not in leaves. Application of methyl jasmonate specifically induced CYP77A19 expression. Expression of either gene in the Arabidopsis null mutant cyp77a6-1 defective in flower cutin restored petal cuticular impermeability. Nanoridges were also observed in CYP77A20-expressing lines. However, only very low levels of the major flower cutin monomer 10,16-dihydroxypalmitate and no C18 epoxy monomers were found in the cutin of the complemented lines. © 2014 John Wiley & Sons Ltd.

The effect of ZnO nanoparticles on liver function in rats

PubMed Central

Tang, Hua-Qiao; Xu, Min; Rong, Qian; Jin, Ru-Wen; Liu, Qi-Ji; Li, Ying-Lun

2016-01-01

Zinc oxide (ZnO) is widely incorporated as a food additive in animal diets. In order to optimize the beneficial effects of ZnO and minimize any resultant environmental pollution, ZnO nanoparticles are often used for delivery of the zinc. However, the possible toxic effects of ZnO nanoparticles, including effects on cytochrome P450 (CYP450) enzymes, have not been evaluated. In this study, we investigated the effect of ZnO nanoparticles, in doses used in animal feeds, on CYP450 enzymes, liver and intestinal enzymes, liver and kidney histopathology, and hematologic indices in rats. We found that liver and kidney injury occurred when the concentrations of ZnO nanoparticles in feed were 300–600 mg/kg. Also, liver mRNA expression for constitutive androstane receptor was suppressed and mRNA expression for pregnane X receptor was induced when feed containing ZnO nanoparticles was given at a concentration of 600 mg/kg. Although the expression of mRNA for CYP 2C11 and 3A2 enzymes was induced by ZnO nanoparticles, the activities of CYP 2C11 and 3A2 were suppressed. While liver CYP 1A2 mRNA expression was suppressed, CYP 1A2 activity remained unchanged at all ZnO nanoparticle doses. Therefore, it has been concluded that ZnO nanoparticles, in the doses customarily added to animal feed, changed the indices of hematology and blood chemistry, altered the expression and activity of hepatic CYP enzymes, and induced pathological changes in liver and kidney tissues of rats. These findings suggest that greater attention needs to be paid to the toxic effects of ZnO nanoparticles in animal feed, with the possibility that the doses of ZnO should be reduced. PMID:27621621

Guanfu base A, an antiarrhythmic alkaloid of Aconitum coreanum, Is a CYP2D6 inhibitor of human, monkey, and dog isoforms.

PubMed

Sun, Jianguo; Peng, Ying; Wu, Hui; Zhang, Xueyuan; Zhong, Yunxi; Xiao, Yanan; Zhang, Fengyi; Qi, Huanhuan; Shang, Lili; Zhu, Jianping; Sun, Yue; Liu, Ke; Liu, Jinghan; A, Jiye; Ho, Rodney J Y; Wang, Guangji

2015-05-01

Guanfu base A (GFA) is a novel heterocyclic antiarrhythmic drug isolated from Aconitum coreanum (Lèvl.) rapaics and is currently in a phase IV clinical trial in China. However, no study has investigated the influence of GFA on cytochrome P450 (P450) drug metabolism. We characterized the potency and specificity of GFA CYP2D inhibition based on dextromethorphan O-demethylation, a CYP2D6 probe substrate of activity in human, mouse, rat, dog, and monkey liver microsomes. In addition, (+)-bufuralol 1'-hydroxylation was used as a CYP2D6 probe for the recombinant form (rCYP2D6), 2D1 (rCYP2D1), and 2D2 (rCYP2D2) activities. Results show that GFA is a potent noncompetitive inhibitor of CYP2D6, with inhibition constant Ki = 1.20 ± 0.33 μM in human liver microsomes (HLMs) and Ki = 0.37 ± 0.16 μM for the human recombinant form (rCYP2D6). GFA is also a potent competitive inhibitor of CYP2D in monkey (Ki = 0.38 ± 0.12 μM) and dog (Ki = 2.4 ± 1.3 μM) microsomes. However, GFA has no inhibitory activity on mouse or rat CYP2Ds. GFA did not exhibit any inhibition activity on human recombinant CYP1A2, 2A6, 2C8, 2C19, 3A4, or 3A5, but showed slight inhibition of 2B6 and 2E1. Preincubation of HLMs and rCYP2D6 resulted in the inactivation of the enzyme, which was attenuated by GFA or quinidine. Beagle dogs treated intravenously with dextromethorphan (2 mg/ml) after pretreatment with GFA injection showed reduced CYP2D metabolic activity, with the Cmax of dextrorphan being one-third that of the saline-treated group and area under the plasma concentration-time curve half that of the saline-treated group. This study suggests that GFA is a specific CYP2D6 inhibitor that might play a role in CYP2D6 medicated drug-drug interaction. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Lack of pharmacokinetic interaction of mipomersen sodium (ISIS 301012), a 2'-O-methoxyethyl modified antisense oligonucleotide targeting apolipoprotein B-100 messenger RNA, with simvastatin and ezetimibe.

PubMed

Yu, Rosie Z; Geary, Richard S; Flaim, Joann D; Riley, Gina C; Tribble, Diane L; vanVliet, André A; Wedel, Mark K

2009-01-01

Mipomersen sodium (ISIS 301012) is a 20-mer phosphorothioate antisense oligonucleotide that is complementary to human apolipoprotein B-100 (apoB-100) messenger RNA and subsequently reduces translation of ApoB-100 protein, the major apolipoprotein of very low-density lipoprotein, intermediate-density lipoprotein and low-density lipoprotein (LDL). Mipomersen sodium is currently being studied in phase II/III clinical studies to determine its clinical utility as add-on therapy to HMG-CoA reductase inhibitors or other lipid-lowering agents in subjects with hypercholesterolaemia. The aim of this study was to characterize the pharmacokinetic interactions of mipomersen sodium with simvastatin and ezetimibe. Another aim was to evaluate the ability of mipomersen sodium to inhibit major cytochrome P450 (CYP) isoenzymes in vitro. In a phase I clinical study, ten healthy subjects per cohort received a single oral dose of simvastatin 40 mg or ezetimibe 10 mg followed by four 2-hour intravenous doses of mipomersen sodium 200 mg over an 8-day period, with simvastatin 40 mg or ezetimibe 10 mg being administered again with the last dose of mipomersen sodium. Mipomersen sodium pharmacokinetic profiles were assessed following the first dose (mipomersen sodium alone) and the last dose (mipomersen sodium in combination with simvastatin or ezetimibe). Plasma samples for measurement of simvastatin, simvastatin acid, and free and total ezetimibe concentrations were collected at various timepoints following their first and last oral dosing. A comparative pharmacokinetic analysis was performed to determine if there were any effects resulting from coadministration of mipomersen sodium with these lipid-lowering drugs. In addition to the clinical pharmacokinetic analysis, the ability of mipomersen sodium to inhibit the major CYP isoform enzymes (namely CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4) was evaluated in cryo-preserved human hepatocytes in vitro. The area under the plasma concentration-time curve (AUC) from 0 to 24 hours (AUC(24)), maximum plasma concentration and apparent elimination half-life values of mipomersen sodium were similar when administered alone and in combination with oral simvastatin or oral ezetimibe. The 90% confidence intervals of the geometric least squares means ratios (%Reference) of the mipomersen sodium AUC(24) values were 93.6, 107 when administered together with simvastatin, and 92.4, 111 when administered with ezetimibe. Therefore, there were no large deviations outside the default no-effect boundaries (80-125%) for total exposure (the AUC) of mipomersen sodium in combination with either simvastatin or ezetimibe. Similarly, large deviations outside the default no-effect boundaries were not observed for simvastatin, simvastatin acid, or free and total ezetimibe exposure in combination with mipomersen sodium. In cryo-preserved human hepatocytes, mipomersen sodium exhibited no cytotoxicity. Significant cell uptake was demonstrated by analysing cell-associated concentrations of mipomersen sodium. All evaluated enzyme activities had <10% inhibition at tested concentrations up to 800 microg/mL (approximately 100 micromol/L) of mipomersen sodium, and dose-dependent inhibition was not observed. Therefore, mipomersen sodium is not considered an inhibitor of CYP1A2, CYP2C9, CYP2C19, CYP2D6 and CYP3A4 enzyme activities. These data provide evidence that mipomersen sodium exhibits no clinically relevant pharmacokinetic interactions with the disposition and clearance of simvastatin or ezetimibe, and vice versa. Moreover, mipomersen sodium does not inhibit any of the major CYP enzymes that were evaluated. Taken together, the results from this study support the use of mipomersen sodium in combination with oral lipid-lowering agents.

Inhibitory effects of spirulina platensis on carcinogen-activating cytochrome P450 isozymes and potential for drug interactions.

PubMed

Savranoglu, Seda; Tumer, Tugba Boyunegmez

2013-01-01

Spirulina platensis (SP) has been considered as potential food source of 21st century due to its remarkable nutrient profile and therapeutic benefits. However, the cytochrome P450 (CYP)-mediated drug/chemical interaction potential of SP has not yet been pursued. We investigated the effects of SP on the expressions and enzymatic activities of main CYP isozymes. After the rats were orally administered with SP daily for 5 consecutive weeks, there were significant downregulations in hepatic expression levels and inhibition in enzymatic activities of CYP1A2 and CYP2E1 compared to controls. In addition, a significant decrease was observed in CYP2C6-associated enzyme activity with no remarkable changes in messenger RNA (mRNA)/protein levels. The SP application resulted in significant increases in mRNA/protein levels of both CYP2B1 and CYP3A1 without a significant change in enzyme activities. These findings partly explain the chemopreventive properties of SP toward various organ toxicities, mutagenesis, and carcinogenesis; however, its coadministration with some CYP substrates may lead to undesirable drug interactions.

Dietary flavonoids modulate CYP2C to improve drug oral bioavailability and their qualitative/quantitative structure-activity relationship.

PubMed

Wang, Hong-Jaan; Pao, Li-Heng; Hsiong, Cheng-Huei; Shih, Tung-Yuan; Lee, Meei-Shyuan; Hu, Oliver Yoa-Pu

2014-03-01

This study aims to improve the drug oral bioavailability by co-administration with flavonoid inhibitors of the CYP2C isozyme and to establish qualitative and quantitative (QSAR) structure-activity relationships (SAR) between flavonoids and CYP2C. A total of 40 naturally occurring flavonoids were screened in vitro for CYP2C inhibition. Enzyme activity was determined by measuring conversion of tolbutamide to 4-hydroxytolbutamide by rat liver microsomes. The percent inhibition and IC50 of each flavonoid were calculated and used to develop SAR and QSAR. The most effective flavonoid was orally co-administered in vivo with a cholesterol-reducing drug, fluvastatin, which is normally metabolized by CYP2C. The most potent CYP2C inhibitor identified in vitro was tamarixetin (IC50 = 1.4 μM). This flavonoid enhanced the oral bioavailability of fluvastatin in vivo, producing a >2-fold increase in the area under the concentration-time curve and in the peak plasma concentration. SAR analysis indicated that the presence of a 2,3-double bond in the C ring, hydroxylation at positions 5, 6, and 7, and glycosylation had important effects on flavonoid-CYP2C interactions. These findings should prove useful for predicting the inhibition of CYP2C activity by other untested flavonoid-like compounds. In the present study, tamarixetin significantly inhibited CYP2C activity in vitro and in vivo. Thus, the use of tamarixetin could improve the therapeutic efficacy of drugs with low bioavailability.

Roles of Human CYP2A6 and Monkey CYP2A24 and 2A26 Cytochrome P450 Enzymes in the Oxidation of 2,5,2',5'-Tetrachlorobiphenyl.

PubMed

Shimada, Tsutomu; Kakimoto, Kensaku; Takenaka, Shigeo; Koga, Nobuyuki; Uehara, Shotaro; Murayama, Norie; Yamazaki, Hiroshi; Kim, Donghak; Guengerich, F Peter; Komori, Masayuki

2016-12-01

2,5,2',5'-Tetrachlorobiphenyl (TCB) induced type I binding spectra with cytochrome P450 (P450) 2A6 and 2A13, with K s values of 9.4 and 0.51 µM, respectively. However, CYP2A6 oxidized 2,5,2',5'-TCB to form 4-hydroxylated products at a much higher rate (∼1.0 minute -1 ) than CYP2A13 (∼0.02 minute -1 ) based on analysis by liquid chromatography-tandem mass spectrometry. Formation of 4-hydroxy-2,5,2',5'-TCB by CYP2A6 was greater than that of 3-hydroxy-2,5,2',5'-TCB and three other hydroxylated products. Several human P450 enzymes, including CYP1A1, 1A2, 1B1, 2B6, 2D6, 2E1, 2C9, and 3A4, did not show any detectable activities in oxidizing 2,5,2',5'-TCB. Cynomolgus monkey CYP2A24, which shows 95% amino acid identity to human CYP2A6, catalyzed 4-hydroxylation of 2,5,2',5'-TCB at a higher rate (∼0.3 minute -1 ) than CYP2A26 (93% identity to CYP2A6, ∼0.13 minute -1 ) and CYP2A23 (94% identity to CYP2A13, ∼0.008 minute -1 ). None of these human and monkey CYP2A enzymes were catalytically active in oxidizing other TCB congeners, such as 2,4,3',4'-, 3,4,3',4'-, and 3,5,3',5'-TCB. Molecular docking analysis suggested that there are different orientations of interaction of 2,5,2',5'-TCB with the active sites (over the heme) of human and monkey CYP2A enzymes, and that ligand interaction energies (U values) of bound protein-ligand complexes show structural relationships of interaction of TCBs and other ligands with active sites of CYP2A enzymes. Catalytic differences in human and monkey CYP2A enzymes in the oxidation of 2,5,2',5'-TCB are suggested to be due to amino acid changes at substrate recognition sites, i.e., V110L, I209S, I300F, V365M, S369G, and R372H, based on the comparison of primary sequences. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

Pharmacogenetic screening for polymorphisms in drug-metabolizing enzymes and drug transporters in a Dutch population.

PubMed

Bosch, T M; Doodeman, V D; Smits, P H M; Meijerman, I; Schellens, J H M; Beijnen, J H

2006-01-01

A possible explanation for the wide interindividual variability in toxicity and efficacy of drug therapy is variation in genes encoding drug-metabolizing enzymes and drug transporters. The allelic frequency of these genetic variants, linkage disequilibrium (LD), and haplotype of these polymorphisms are important parameters in determining the genetic differences between patients. The aim of this study was to explore the frequencies of polymorphisms in drug-metabolizing enzymes (CYP1A1, CYP2C9, CYP2C19, CYP3A4, CYP2D6, CYP3A5, DPYD, UGT1A1, GSTM1, GSTP1, GSTT1) and drug transporters (ABCB1[MDR1] and ABCC2[MRP2]), and to investigate the LD and perform haplotype analysis of these polymorphisms in a Dutch population. Blood samples were obtained from 100 healthy volunteers and genomic DNA was isolated and amplified by PCR. The amplification products were sequenced and analyzed for the presence of polymorphisms by sequence alignment. In the study population, we identified 13 new single nucleotide polymorphisms (SNPs) in Caucasians and three new SNPs in non-Caucasians, in addition to previously recognized SNPs. Three of the new SNPs were found within exons, of which two resulted in amino acid changes (A428T in CYP2C9 resulting in the amino acid substitution D143V; and C4461T in ABCC2 in a non-Caucasian producing the amino acid change T1476M). Several LDs and haplotypes were found in the Caucasian individuals. In this Dutch population, the frequencies of 16 new SNPs and those of previously recognized SNPs were determined in genes coding for drug-metabolizing enzymes and drug transporters. Several LDs and haplotypes were also inferred. These data are important for further research to help explain the interindividual pharmacokinetic and pharmacodynamic variability in response to drug therapy.

The impact of cytochrome P450 2C19 polymorphism on the occurrence of one-year in-stent restenosis in patients who underwent percutaneous coronary intervention: A case-match study

PubMed Central

Nozari, Younes; Vosooghi, Sirous; Boroumand, Mohammadali; Poorhosseini, Hamidreza; Nematipour, Ebrahim; Salarifar, Mojtaba; Kassaian, Seyed Ebrahim; Amirzadegan, Alireza; Alidoosti, Mohammad; Haji-Zeinali, Ali-Mohammad; Saroukhani, Sepideh

2015-01-01

Objective In this case-match study, we evaluated the impact of the CYP2C19*2 polymorphism in the occurrence of in-stent restenosis during a 1-year follow-up period despite adequate dual anti-platelet therapy in Iranian patients having undergone percutaneous coronary intervention (PCI). Methods This study, conducted at a tertiary referral heart center in Tehran, recruited 100 patients: 50 patients had in-stent restenosis after PCI during a 1-year follow-up and were compared to another 50 patients without in-stent restenosis who were individually matched according to sex. In order to evaluate the impact of the CYP2C19*2 polymorphism, case frequency matching was performed with respect to variables previously shown to be predictors of in-stent restenosis. The CYP2C19*2 polymorphism evaluated using real-time PCR methods. Results Among all 100 patients (mean age=60.09±10.29: 72.0% male), 89 (89%) patients had wild (CYP2C19*1/CYP2C19*1) and 11% had a heterozygous (CYP2C19*1/CYP2C19*2) genotypes, and there was no patient with a completely mutant genotype (CYP2C19*2/CYP2C19*2). Conditional logistic regression analysis showed that there was no significant association between genotype CYP2C19*1/CYP2C19*2 and the occurrence of in-stent restenosis after PCI (OR=2.5, p value=0.273). Conclusion Our findings indicated that carrying a CYP2C19*2 allele with a functional CYP2C19*1 allele had no significant association with instent restenosis 1 year after PCI. The antiplatelet treatment strategy for non-functional allele carriers is still a matter of controversy. Further studies with larger sample sizes are necessary to determine the prevalence of non-functional alleles in various populations and to achieve a consensus about the effective treatment strategy. PMID:25993709

Characteristic CYP2A6 genetic polymorphisms detected by TA cloning-based sequencing in Chinese digestive system cancer patients with S-1 based chemotherapy.

PubMed

Fang, Wei-Jia; Mou, Hai-Bo; Jin, Da-Zhi; Zheng, Yu-Long; Zhao, Peng; Mao, Chen-Yu; Peng, Ling; Huang, Ming-Zhu; Xu, Nong

2012-05-01

S-1 is an oral antitumor agent that contains tegafur, which is converted to fluorouracil (5-FU) in the human body. Cytochrome P450 2A6 (CYP2A6) is the principal enzyme responsible for bioconversion of tegafur to 5-FU. A number of CYP2A6 polymorphisms have been associated with variations in enzyme activity in several ethnic populations. The CYP2A6*4C allele leads to deletion of the entire CYP2A6 gene, and is the main finding in patients with reduced CYP2A6 enzymatic activity. Thus, the aim of our study was to evaluate the allele frequencies of CYP2A6 polymorphisms in a population with cancer of the digestive system. We developed a simple screening method, which combined TA cloning and direct-sequencing, to detect CYP2A6 genetic polymorphisms in Chinese patients with cancers of the digestive system. A total of 77 patients with various types of digestive system cancers were screened for CYP2A6 genetic polymorphisms. The allele frequencies of CYP2A6*1A, CYP2A6*1B and CYP2A6*4C in the 77 patients screened were 62, 42 and 13%, respectively. Frequencies of the homozygous genotypes for CYP2A6*1A and CYP2A6*4C were 27 and 12%, respectively. As expected, patients that were determined to be homozygous for CYP2A6*4C exhibited the characteristic chemotherapy efficacy and toxicity profiles. The TA cloning-based direct sequencing method facilitated allele frequency and genotyping determination for CYP2A6*1A, 1B and 4C of cancer patients. The findings indicated that the population carries a high frequency of the CYP2A6*4C homozygous genotype. Thus, the reduced efficacy of standard chemotherapy dosage in Chinese cancer patients may be explained by the lack of CYP2A6-mediated S-1 bioconversion to 5-FU.

CYP2C9 genotype vs. metabolic phenotype for individual drug dosing--a correlation analysis using flurbiprofen as probe drug.

PubMed

Vogl, Silvia; Lutz, Roman W; Schönfelder, Gilbert; Lutz, Werner K

2015-01-01

Currently, genotyping of patients for polymorphic enzymes responsible for metabolic elimination is considered a possibility to adjust drug dose levels. For a patient to profit from this procedure, the interindividual differences in drug metabolism within one genotype should be smaller than those between different genotypes. We studied a large cohort of healthy young adults (283 subjects), correlating their CYP2C9 genotype to a simple phenotyping metric, using flurbiprofen as probe drug. Genotyping was conducted for CYP2C9*1, *2, *3. The urinary metabolic ratio MR (concentration of CYP2C9-dependent metabolite divided by concentration of flurbiprofen) determined two hours after flurbiprofen (8.75 mg) administration served as phenotyping metric. Linear statistical models correlating genotype and phenotype provided highly significant allele-specific MR estimates of 0.596 for the wild type allele CYP2C9*1, 0.405 for CYP2C9*2 (68 % of wild type), and 0.113 for CYP2C9*3 (19 % of wild type). If these estimates were used for flurbiprofen dose adjustment, taking 100 % for genotype *1/*1, an average reduction to 84 %, 60 %, 68 %, 43 %, and 19 % would result for genotype *1/*2, *1/*3, *2/*2, *2/*3, and *3/*3, respectively. Due to the large individual variation within genotypes with coefficients of variation ≥ 20 % and supposing the normal distribution, one in three individuals would be out of the average optimum dose by more than 20 %, one in 20 would be 40 % off. Whether this problem also applies to other CYPs and other drugs has to be investigated case by case. Our data for the given example, however, puts the benefit of individual drug dosing to question, if it is exclusively based on genotype.

Influence of CYP2D6 and CYP2C19 genotypes on venlafaxine metabolic ratios and stereoselective metabolism in forensic autopsy cases.

PubMed

Karlsson, L; Zackrisson, A-L; Josefsson, M; Carlsson, B; Green, H; Kugelberg, F C

2015-04-01

We investigated whether polymorphisms in the CYP2D6 and CYP2C19 genes influence the metabolic ratios and enantiomeric S/R ratios of venlafaxine (VEN) and its metabolites O-desmethylvenlafaxine (ODV), N-desmethylvenlafaxine (NDV) and N,O-didesmethylvenlafaxine (DDV) in blood from forensic autopsy cases. In all, 94 postmortem cases found positive for VEN during toxicological screening were included. The CYP2D6 genotype was shown to significantly influence the ODV/VEN (P=0.003), DDV/NDV (P=0.010) and DDV/ODV (P=0.034) ratios. The DDV/ODV (P=0.013) and DDV/VEN (P=0.021) ratios were significantly influenced by the CYP2C19 genotype. The S/R ratios of VEN were significantly influenced by both CYP2D6 and CYP2C19 genotypes. CYP2D6 poor metabolizers (PMs) had lower S/R VEN ratios and CYP2C19 PMs had high S/R ratios of VEN in comparison. Our results show that the CYP2D6 genotype influences the O-demethylation whereas CYP2C19 influences the N-demethylation of VEN and its metabolites. In addition, we show a stereoselective metabolism where CYP2D6 favours the R-enantiomer whereas CYP2C19 favours the S-enantiomer.

Pharmacokinetic drug interactions with clopidogrel: updated review and risk management in combination therapy

PubMed Central

Wang, Zhi-Yu; Chen, Meng; Zhu, Ling-Ling; Yu, Lu-Shan; Zeng, Su; Xiang, Mei-Xiang; Zhou, Quan

2015-01-01

Background Coprescribing of clopidogrel and other drugs is common. Available reviews have addressed the drug–drug interactions (DDIs) when clopidogrel is as an object drug, or focused on combination use of clopidogrel and a special class of drugs. Clinicians may still be ignorant of those DDIs when clopidogrel is a precipitant drug, the factors determining the degree of DDIs, and corresponding risk management. Methods A literature search was performed using PubMed, MEDLINE, Web of Science, and the Cochrane Library to analyze the pharmacokinetic DDIs of clopidogrel and new P2Y12 receptor inhibitors. Results Clopidogrel affects the pharmacokinetics of cerivastatin, repaglinide, ferulic acid, sibutramine, efavirenz, and omeprazole. Low efficacy of clopidogrel is anticipated in the presence of omeprazole, esomeprazole, morphine, grapefruit juice, scutellarin, fluoxetine, azole antifungals, calcium channel blockers, sulfonylureas, and ritonavir. Augmented antiplatelet effects are anticipated when clopidogrel is coprescribed with aspirin, curcumin, cyclosporin, St John’s wort, rifampicin, and angiotensin-converting enzyme inhibitors. The factors determining the degree of DDIs with clopidogrel include genetic status (eg, cytochrome P540 [CYP]2B6*6, CYP2C19 polymorphism, CYP3A5*3, CYP3A4*1G, and CYP1A2-163C.A), species differences, and dose strength. The DDI risk does not exhibit a class effect, eg, the effects of clopidogrel on cerivastatin versus other statins, the effects of proton pump inhibitors on clopidogrel (omeprazole, esomeprazole versus pantoprazole, rabeprazole), the effects of rifampicin on clopidogrel versus ticagrelor and prasugrel, and the effects of calcium channel blockers on clopidogrel (amlodipine versus P-glycoprotein-inhibiting calcium channel blockers). The mechanism of the DDIs with clopidogrel involves modulating CYP enzymes (eg, CYP2B6, CYP2C8, CYP2C19, and CYP3A4), paraoxonase-1, hepatic carboxylesterase 1, P-glycoprotein, and organic anion transporter family member 1B1. Conclusion Effective and safe clopidogrel combination therapy can be achieved by increasing the awareness of potential changes in efficacy and toxicity, rationally selecting alternatives, tailoring drug therapy based on genotype, checking the appropriateness of physician orders, and performing therapeutic monitoring. PMID:25848291

Distinct patterns of dysregulated expression of enzymes involved in androgen synthesis and metabolism in metastatic prostate cancer tumors

PubMed Central

Mitsiades, Nicholas; Sung, Clifford C.; Schultz, Nikolaus; Danila, Daniel C.; He, Bin; Eedunuri, Vijay Kumar; Fleisher, Martin; Sander, Chris; Sawyers, Charles L.; Scher, Howard I.

2012-01-01

Androgen receptor (AR) signaling persists in castration-resistant prostate carcinomas (CRPCs), due to several mechanisms that include increased AR expression and intratumoral androgen metabolism. We investigated the mechanisms underlying aberrant expression of transcripts involved in androgen metabolism in CRPC. We compared gene expression profiles and DNA copy number alteration (CNA) data from 29 normal prostate tissue samples, 127 primary prostate carcinomas (PCas) and 19 metastatic PCas. Steroidogenic enzyme transcripts were evaluated by qRT-PCR in PCa cell lines and circulating tumor cells (CTCs) from CRPC patients. Metastatic PCas expressed higher transcript levels for AR and several steroidogenic enzymes, including SRD5A1, SRD5A3, and AKR1C3, while expression of SRD5A2, CYP3A4, CYP3A5 and CYP3A7 was decreased. This aberrant expression was rarely associated with CNAs. Instead, our data suggest distinct patterns of coordinated aberrant enzyme expression. Inhibition of AR activity by itself stimulated AKR1C3 expression. The aberrant expression of the steroidogenic enzyme transcripts were detected in CTCs from CRPC patients. In conclusion, our findings identify substantial interpatient heterogeneity and distinct patterns of dysregulated expression of enzymes involved in intratumoral androgen metabolism in PCa. These steroidogenic enzymes represent targets for complete suppression of systemic and intratumoral androgen levels, an objective that is supported by the clinical efficacy of the CYP17 inhibitor abiraterone. A comprehensive AR axis targeting approach via simultaneous, frontline enzymatic blockade and/or transcriptional repression of several steroidogenic enzymes, in combination with GnRH analogs and potent anti-androgens, would represent a powerful future strategy for PCa management. PMID:22971343

Inhibitory Effect of Apigenin on Losartan Metabolism and CYP2C9 Activity in vitro.

PubMed

Wang, Zhe; Gong, Yun; Zeng, Da-Li; Chen, Lian-Guo; Lin, Gao-Tong; Huang, Cheng-Ke; Sun, Wei; Chen, Meng-Chun; Hu, Guo-Xin; Chen, Rui-Jie

2016-01-01

CYP2C9 is one of the most important phase I drug-metabolizing enzymes in liver. The objective of this work was to investigate the effects of apigenin on the metabolism of losartan and human CYP2C9 and rat CYP2C11 activity in vitro. Different concentrations of apigenin were added to a 100 mmol/l Tris-HCl reaction mixture containing 2 pmol/ml recombinant human CYP2C9.1, 0.25 mg/ml human liver microsomes or 0.5 mg/ml rat liver microsomes to determine the half maximal inhibition or a half-maximal inhibitory concentration (IC50) on the metabolism of losartan. In addition, diclofenac used as CYP2C9 substrate was performed to determine the effects of apigenin on CYP2C9. The results showed that apigenin has the inhibitory effect on the metabolism of losartan in vitro, the IC50 was 7.61, 4.10 and 11.07 μmol/l on recombinant CYP2C9 microsomes, human liver microsomes and rat liver microsomes, respectively. Meanwhile, apigenin's mode of action on human CYP2C9 activity was competitive for the substrate diclofenac. In contrast to its potent inhibition of CYP2C9 in humans (9.51 μmol/l), apigenin had lesser effects on CYP2C11 in rat (IC50 = 15.51 μmol/l). The observations imply that apigenin has the inhibitory effect on the metabolism of losartan and CYP2C9 activity in vitro. More attention should be paid as to when losartan should be administrated combined with apigenin. © 2016 S. Karger AG, Basel.

A tryptophan derivative, ITE, enhances liver cell metabolic functions in vitro

PubMed Central

Zhang, Xiaoqian; Lu, Juan; He, Bin; Tang, Lingling; Liu, Xiaoli; Zhu, Danhua; Cao, Hongcui; Wang, Yingjie; Li, Lanjuan

2017-01-01

Cell encapsulation provides a three-dimensional support by incorporating isolated cells into microcapsules with the goal of simultaneously maintaining cell survival and function, as well as providing active transport for a bioreactor in vitro similarly to that observed in vivo. However, the biotransformation and metabolic functions of the encapsulated cells are not satisfactory for clinical applications. For this purpose, in this study, hepatoma-derived Huh7 cells/C3A cells were treated with 2-(1′H-indole-3′-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE), an endogenous non-toxic ligand for aryl hydrocarbon receptor, in monolayer cultures and on microspheres. The mRNA and protein levels, as well as the metabolic activities of drug metabolizing enzymes, albumin secretion and urea synthesis were determined. When the Huh7 and C3A cells cultured in a monolayer on two-dimensional surfaces, ITE enhanced the protein levels and the metabolic activities of the major cytochrome P450 (CYP450) enzymes, CYP1A1, CYP1A2, CYP3A4 and CYP1B1, and slightly increased albumin secretion and urea synthesis. Moreover, when cultured on microspheres, ITE also substantially increased the protein levels and metabolic activities of CYP1A1, CYP1A2, CYP3A4 and CYP1B1 in both liver cell lines. On the whole, our findings indicate that ITE enhances the enzymatic activities of major CYP450 enzymes and the metabolic functions of liver cells cultured in monolayer or on microspheres, indicating that it may be utilized to improve the functions of hepatocytes. Thus, it may be used in the future for the treatment of liver diseases. PMID:27959388

A tryptophan derivative, ITE, enhances liver cell metabolic functions in vitro.

PubMed

Zhang, Xiaoqian; Lu, Juan; He, Bin; Tang, Lingling; Liu, Xiaoli; Zhu, Danhua; Cao, Hongcui; Wang, Yingjie; Li, Lanjuan

2017-01-01

Cell encapsulation provides a three-dimensional support by incorporating isolated cells into microcapsules with the goal of simultaneously maintaining cell survival and function, as well as providing active transport for a bioreactor in vitro similarly to that observed in vivo. However, the biotra-nsformation and metabolic functions of the encapsulated cells are not satisfactory for clinical applications. For this purpose, in this study, hepatoma-derived Huh7 cells/C3A cells were treated with 2-(1'H-indole-3'-carbonyl)-thiazole-4-carboxylic acid methyl ester (ITE), an endogenous non-toxic ligand for aryl hydrocarbon receptor, in monolayer cultures and on microspheres. The mRNA and protein levels, as well as the metabolic activities of drug metabolizing enzymes, albumin secretion and urea synthesis were determined. When the Huh7 and C3A cells cultured in a monolayer on two‑dimensional surfaces, ITE enhanced the protein levels and the metabolic activities of the major cytochrome P450 (CYP450) enzymes, CYP1A1, CYP1A2, CYP3A4 and CYP1B1, and slightly increased albumin secretion and urea synthesis. Moreover, when cultured on microspheres, ITE also substantially increased the protein levels and metabolic activities of CYP1A1, CYP1A2, CYP3A4 and CYP1B1 in both liver cell lines. On the whole, our findings indicate that ITE enhances the enzymatic activities of major CYP450 enzymes and the metabolic functions of liver cells cultured in monolayer or on microspheres, indicating that it may be utilized to improve the functions of hepatocytes. Thus, it may be used in the future for the treatment of liver diseases.

Mutation of foxl2 or cyp19a1a Results in Female to Male Sex Reversal in XX Nile Tilapia.

PubMed

Zhang, Xianbo; Li, Mengru; Ma, He; Liu, Xingyong; Shi, Hongjuan; Li, Minghui; Wang, Deshou

2017-08-01

It is well accepted that Forkhead box protein L2 (Foxl2) and aromatase (Cyp19a1; the enzyme responsible for estrogen synthesis) are critical for ovarian development in vertebrates. Knockouts of Foxl2 and Cyp19a1 in goat, mouse, and zebrafish have revealed similar but not identical functions across species. Functional analyses of these two genes in other animals are needed to elucidate their conserved roles in vertebrate sexual development. In this study, we established foxl2 and cyp19a1a mutant lines in Nile tilapia. Both foxl2-/- and cyp19a1a-/- XX fish displayed female-to-male sex reversal. Sf1, Dmrt1, and Gsdf were upregulated in the foxl2-/- and the cyp19a1a-/- XX gonads. Downregulation of Cyp19a1a and serum estradiol-17β level, and upregulation of Cyp11b2 and serum 11-ketotestosterone level were observed in foxl2-/- XX fish. The mutant phenotype of foxl2-/- XX individuals could be rescued by 17β-estradiol treatment from 5 to 30 days after hatching (dah). Upregulation of Star1, the enzyme involved in androgen production in tilapia, was also observed in the foxl2-/- XX gonad at 30 and 90 dah. In vitro promoter analyses consistently demonstrated that Foxl2 could suppress the transcription of star1 in a dose-dependent manner. In addition, compared with the control XX gonad, fewer germ cells were detected in the foxl2-/- XX, cyp19a1a-/- XX, and control XY gonads 10 dah. These results demonstrate that Foxl2 promotes ovarian development by upregulating Cyp19a1a expression and repressing male pathway gene expression. These results extend the study of Foxl2 and Cyp19a1a loss of function to a commercially important fish species. Copyright © 2017 Endocrine Society.

Association of CYP2B6, CYP3A5, and CYP2C19 genetic polymorphisms with sibutramine pharmacokinetics in healthy Korean subjects.

PubMed

Kim, K A; Song, W K; Park, J Y

2009-11-01

We assessed the association of CYP2B6, CYP3A5, and CYP2C19 polymorphisms with sibutramine pharmacokinetics. Forty six healthy male subjects were enrolled, and their CYP2B6 (*4 and *6), CYP3A5 (*3), and CYP2C19 (*2, and *3) genotypes were analyzed. After a single 15-mg dose of sibutramine was administered, plasma concentrations of sibutramine and its metabolites, M1 and M2, were measured. CYP2B6 and CYP3A5 polymorphisms did not affect the pharmacokinetics of sibutramine and its metabolites. However, the CYP2C19 genotype substantially influenced plasma levels of sibutramine and its metabolites. The mean area under the curve (AUC) of sibutramine in CYP2C19 intermediate metabolizers (IMs; *1/*2 or *1/*3) and poor metabolizers (PMs; *2/*2, *2/*3)) was 18.5 and 252.2% higher, respectively, than the AUC in extensive metabolizers (EMs, *1/*1) (P < 0.001). The AUC of M1 metabolite in IMs and PMs was 22.5 and 148.0% higher, respectively, than that of EMs (P < 0.001). Our findings indicate that the CYP2C19 genotype substantially affects the pharmacokinetics of sibutramine.

Characterization and expression profile of the ovarian cytochrome P-450 aromatase (cyp19A1) gene during thermolabile sex determination in Pejerrey, Odontesthes bonariensis

USGS Publications Warehouse

Karube, M.; Fernandino, J.I.; Strobl-Mazzulla, P.; Strussmann, C.A.; Yoshizaki, G.; Somoza, G.M.; Patino, R.

2007-01-01

Cytochrome P450 aromatase (cyp19) is an enzyme that catalyzes the conversion of androgens to estrogens and may play a role in temperature- dependent sex determination (TSD) of reptiles, amphibians, and fishes. In this study, the ovarian P450 aromatase form (cyp19A1) of pejerrey Odontesthes bonariensis, a teleost with marked TSD, was cloned and its expression profile evaluated during gonadal differentiation at feminizing (17??C, 100% females), mixed-sex producing (24 and 25??C, 73.3 and 26.7% females, respectively), and masculinizing (29??C, 0% females) temperatures. The deduced cyp19A1 amino acid sequence shared high identity (>77.8%) with that from other teleosts but had low identity (<61.8%) with brain forms (cyp19A2), including that of pejerrey itself. The tissue distribution analysis of cyp19A1 mRNA in adult fish revealed high expression in the ovary. Semi-quantitative reverse transcription polymerase chain reaction analysis of the bodies of larvae revealed that cyp19A1 expression increased before the appearance of the first histological signs of ovarian differentiation at the feminizing temperature but remained low at the masculinizing temperature. The expression levels at mixed-sex producing temperatures were bimodal rather than intermediate, showing low and high modal values similar to those at the feminizing and masculinizing temperatures, respectively. The population percentages of high and low expression levels at intermediate temperatures were proportional to the percentage of females and males, respectively, and high levels were first observed at about the time of sex differentiation of females. These results suggest that cyp19A1 is involved in the process of ovarian formation and possibly also in the TSD of pejerrey. ?? 2007 Wiley-Liss, Inc.

Effects of sexually dimorphic growth hormone secretory patterns on arachidonic acid metabolizing enzymes in rodent heart

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Furong; Yu, Xuming; He, Chunyan

The arachidonic acid (AA) metabolizing enzymes are the potential therapeutic targets of cardiovascular diseases (CVDs). As sex differences have been shown in the risk and outcome of CVDs, we investigated the regulation of heart AA metabolizing enzymes (COXs, LOXs, and CYPs) by sex-dependent growth hormone (GH) secretory patterns. The pulsatile (masculine) GH secretion at a physiological concentration decreased CYP1A1 and CYP2J3 mRNA levels more efficiently in the H9c2 cells compared with the constant (feminine) GH secretion; however, CYP1B1 mRNA levels were higher following the pulsatile GH secretion. Sex differences in CYP1A1, CYP1B1, and CYP2J11 mRNA levels were observed in bothmore » the wild-type and GHR deficient mice. No sex differences in the mRNA levels of COXs, LOXs, or CYP2E1 were observed in the wild-type mice. The constant GH infusion induced heart CYP1A1 and CYP2J11, and decreased CYP1B1 in the male C57/B6 mice constantly infused with GH (0.4 μg/h, 7 days). The activity of rat Cyp2j3 promoter was inhibited by the STAT5B protein, but was activated by C/EBPα (CEBPA). Compared with the constant GH administration, the levels of the nuclear phosphorylated STAT5B protein and its binding to the rat Cyp2j3 promoter were higher following the pulsatile GH administration. The constant GH infusion decreased the binding of the nuclear phosphorylated STAT5B protein to the mouse Cyp2j11 promoter. The data suggest the sexually dimorphic transcription of heart AA metabolizing enzymes, which might alter the risk and outcome of CVDs. GHR-STAT5B signal transduction pathway may be involved in the sex difference in heart CYP2J levels. - Highlights: • The transcription of heart Cyp1a1, Cyp1b1 and Cyp2j genes is sexually dimorphic. • There are no sex differences in the mRNA levels of heart COXs, LOXs, or CYP2E1. • GHR-STAT5B pathway is involved in sexually dimorphic transcription of heart Cpy2j genes. • Heart CYPs-mediated metabolism pathway of arachidonic acid may be sex different.« less

[Effect of Panax notoginseng saponins on liver drug metablic enzyme activity, mRNA and protein expressions in rats].

PubMed

Chen, Yan-Jin; Wang, Yu-Guang; Ma, Zeng-Chun; Xiao, Cheng-Rong; Tan, Hong-Ling; Liang, Qian-De; Tang, Xiang-Lin; Zhao, Yong-Hong; Wang, Dong-Gen; Gao, Yue

2014-10-01

To study the effect of Panax notoginseng saponins (PNS) on liver drug metabolic enzyme activity, mRNA and protein expressions in rats. Male Wistar rats were randomly divided into nine groups. After administration of the test drugs, their liver microsomes, liver total RNA and total protein were extracted to detect the regulating effect of PNS on liver drug metabolic enzyme activity-related subtype enzymatic activity, mRNA and protein expression by substrate probe, quantitative PCR and Western Blot technology. The result of this experiment was that PNS could significantly induce CYP1A2 and CYP2E1 enzyme activity, mRNA expression, CYP2E1 protein expression level. PNS significantly induced CYP3A mRNA expression, but with no significant effect in CYP3A enzyme activity level. PNS had no significant effect CYP1A1 and CYP2B mRNA expressions and enzyme activity levels. PNS had selective regulations on different P450 subtypes, and the major subtypes were CYP1A2 and CYP2E1. In clinical practice, particularly in the combination with CYP1A2 and CYP2E1 metabolism-related drugs, full consideration shall be given to the possible drug interactions in order to avoid potential toxic and side effects. Meanwhile, whether the induction effect of CYP2E1 gets involved in ginsenoside's effect incavenging free radicals deserves further studies.

Pharmacokinetic Effects of Isavuconazole Coadministration With the Cytochrome P450 Enzyme Substrates Bupropion, Repaglinide, Caffeine, Dextromethorphan, and Methadone in Healthy Subjects.

PubMed

Yamazaki, Takao; Desai, Amit; Goldwater, Ronald; Han, David; Howieson, Corrie; Akhtar, Shahzad; Kowalski, Donna; Lademacher, Christopher; Pearlman, Helene; Rammelsberg, Diane; Townsend, Robert

2017-01-01

This report describes phase 1 clinical trials performed to assess interactions of oral isavuconazole at the clinically targeted dose (200 mg, administered as isavuconazonium sulfate 372 mg, 3 times a day for 2 days; 200 mg once daily [QD] thereafter) with single oral doses of the cytochrome P450 (CYP) substrates: bupropion hydrochloride (CYP2B6; 100 mg; n = 24), repaglinide (CYP2C8/CYP3A4; 0.5 mg; n = 24), caffeine (CYP1A2; 200 mg; n = 24), dextromethorphan hydrobromide (CYP2D6/CYP3A4; 30 mg; n = 24), and methadone (CYP2B6/CYP2C19/CYP3A4; 10 mg; n = 23). Compared with each drug alone, coadministration with isavuconazole changed the area under the concentration-time curves (AUC ∞ ) and maximum concentrations (C max ) as follows: bupropion, AUC ∞ reduced 42%, C max reduced 31%; repaglinide, AUC ∞ reduced 8%, C max reduced 14%; caffeine, AUC ∞ increased 4%, C max reduced 1%; dextromethorphan, AUC ∞ increased 18%, C max increased 17%; R-methadone, AUC ∞ reduced 10%, C max increased 3%; S-methadone, AUC ∞ reduced 35%, C max increased 1%. In all studies, there were no deaths, 1 serious adverse event (dextromethorphan study; perioral numbness, numbness of right arm and leg), and adverse events leading to study discontinuation were rare. Thus, isavuconazole is a mild inducer of CYP2B6 but does not appear to affect CYP1A2-, CYP2C8-, or CYP2D6-mediated metabolism. © 2016 The Authors. Clinical Pharmacology in Drug Development Published by Wiley Periodicals, Inc. on behalf of The American College of Clinical Pharmacology.

Pharmacokinetic study of isocorynoxeine metabolites mediated by cytochrome P450 enzymes in rat and human liver microsomes.

PubMed

Zhao, Lizhu; Zang, Bin; Qi, Wen; Chen, Fangfang; Wang, Haibo; Kano, Yoshihiro; Yuan, Dan

2016-06-01

Isocorynoxeine (ICN) is one of the major bioactive tetracyclic oxindole alkaloids found in Uncaria rhynchophylla (Miq.) Jacks. that is widely used for the treatment of hypertension, vascular dementia, and stroke. The present study was undertaken to assess the plasma pharmacokinetic characteristics of major ICN metabolites, and the role of simulated gastric and intestinal fluid (SGF and SIF), human and rat liver microsomes (HLMs and RLMs), and seven recombinant human CYP enzymes in the major metabolic pathway of ICN. A rapid, sensitive and accurate UHPLC/Q-TOF MS method was validated for the simultaneous determination of ICN and its seven metabolites in rat plasma after oral administration of ICN at 40mg/kg. It was found that 18.19-dehydrocorynoxinic acid (DCA) and 5-oxoisocorynoxeinic acid (5-O-ICA) were both key and predominant metabolites, rather than ICN itself, due to the rapid and extensive metabolism of ICN in vivo. The further study indicated that ICN was mainly metabolized in human or rat liver, and CYPs 2C19, 3A4 and 2D6 were the major enzymes responsible for the biotransformation of ICN to DCA and 5-O-ICA in human. These findings are of significance in understanding of the pharmacokinetic nature of tetracyclic oxindole alkaloids, and provide helpful information for the clinical co-administration of the herbal preparations containing U. rhynchophylla with antihypertensive drugs that are mainly metabolized by CYP3A4 and CYP2C19. Copyright © 2016 Elsevier B.V. All rights reserved.

Interaction of rocuronium with human liver cytochromes P450.

PubMed

Anzenbacherova, Eva; Spicakova, Alena; Jourova, Lenka; Ulrichova, Jitka; Adamus, Milan; Bachleda, Petr; Anzenbacher, Pavel

2015-02-01

Rocuronium is a neuromuscular blocking agent acting as a competitive antagonist of acetylcholine. Results of an inhibition of eight individual liver microsomal cytochromes P450 (CYP) are presented. As the patients are routinely premedicated with diazepam, possible interaction of diazepam with rocuronium has been also studied. Results indicated that rocuronium interacts with human liver microsomal CYPs by binding to the substrate site. Next, concentration dependent inhibition of liver microsomal CYP3A4 down to 42% (at rocuronium concentration 189 μM) was found. This effect has been confirmed with two CYP3A4 substrates, testosterone (formation of 6β-hydroxytestosterone) and diazepam (temazepam formation). CYP2C9 and CYP2C19 activities were inhibited down to 75-80% (at the same rocuronium concentration). Activities of other microsomal CYPs have not been inhibited by rocuronium. To prove the possibility of rocuronium interaction with other drugs (diazepam), the effect of rocuronium on formation of main diazepam metabolites, temazepam (by CYP3A4) and desmethyldiazepam, (also known as nordiazepam; formed by CYP2C19) in primary culture of human hepatocytes has been examined. Rocuronium has caused inhibition of both reactions by 20 and 15%, respectively. The results open a possibility that interactions of rocuronium with drugs metabolized by CYP3A4 (and possibly also CYP2C19) may be observed. Copyright © 2014 Japanese Pharmacological Society. Production and hosting by Elsevier B.V. All rights reserved.

NF-KappaB2/p52 Activation and Androgen Receptor Signaling in Prostate Cancer

DTIC Science & Technology

2011-08-01

biosynthetic enzymes including AKR1C3, CYP17A1, HSD3B2, and SRD5A1 were found to be elevated in CaP cells expressing NF-kappaB2/p52. Luciferase assays...RESULTS: Expression levels of androgen biosynthetic enzymes including AKR1C3, CYP17A1, HSD3B2, and SRD5A1 were found to be elevated in CaP cells

The steroid metabolite 16(β)-OH-androstenedione generated by CYP21A2 serves as a substrate for CYP19A1.

PubMed

Neunzig, J; Milhim, M; Schiffer, L; Khatri, Y; Zapp, J; Sánchez-Guijo, A; Hartmann, M F; Wudy, S A; Bernhardt, R

2017-03-01

The 21-hydroxylase (CYP21A2) is a steroidogenic enzyme crucial for the synthesis of mineralo- and glucocorticoids. It is described to convert progesterone as well as 17-OH-progesterone, through a hydroxylation at position C21, into 11-deoxycorticosterone (DOC) and 11-deoxycortisol (RSS), respectively. In this study we unraveled CYP21A2 to have a broader steroid substrate spectrum than assumed. Utilizing a reconstituted in vitro system, consisting of purified human CYP21A2 and human cytochrome P450 reductase (CPR) we demonstrated that CYP21A2 is capable to metabolize DOC, RSS, androstenedione (A4) and testosterone (T). In addition, the conversion of A4 rendered a product whose structure was elucidated through NMR spectroscopy, showing a hydroxylation at position C16-beta. The androgenic properties of this steroid metabolite, 16(β)-OH-androstenedione (16bOHA4), were investigated and compared with A4. Both steroid metabolites were shown to be weak agonists for the human androgen receptor. Moreover, the interaction of 16bOHA4 with the aromatase (CYP19A1) was compared to that of A4, indicating that the C16 hydroxyl group does not influence the binding with CYP19A1. In contrast, the elucidation of the kinetic parameters showed an increased K m and decreased k cat value resulting in a 2-fold decreased catalytic efficiency compared to A4. These findings were in accordance with our docking studies, revealing a similar binding conformation and distance to the heme iron of both steroids. Furthermore, the product of 16bOHA4, presumably 16-hydroxy-estrone (16bOHE1), was investigated with regard to its estrogenic activity, which was negligible compared to estradiol and estrone. Finally, 16bOHA4 was found to be present in a patient with 11-hydroxylase deficiency and in a patient with an endocrine tumor. Taken together, this study provides novel information on the steroid hormone biosynthesis and presents a new method to detect further potential relevant novel steroid metabolites. Copyright © 2017 Elsevier Ltd. All rights reserved.

Short-term fasting alters cytochrome P450-mediated drug metabolism in humans.

PubMed

Lammers, Laureen A; Achterbergh, Roos; de Vries, Emmely M; van Nierop, F Samuel; Klümpen, Heinz-Josef; Soeters, Maarten R; Boelen, Anita; Romijn, Johannes A; Mathôt, Ron A A

2015-06-01

Experimental studies indicate that short-term fasting alters drug metabolism. However, the effects of short-term fasting on drug metabolism in humans need further investigation. Therefore, the aim of this study was to evaluate the effects of short-term fasting (36 h) on P450-mediated drug metabolism. In a randomized crossover study design, nine healthy subjects ingested a cocktail consisting of five P450-specific probe drugs [caffeine (CYP1A2), S-warfarin (CYP2C9), omeprazole (CYP2C19), metoprolol (CYP2D6), and midazolam (CYP3A4)] on two occasions (control study after an overnight fast and after 36 h of fasting). Blood samples were drawn for pharmacokinetic analysis using nonlinear mixed effects modeling. In addition, we studied in Wistar rats the effects of short-term fasting on hepatic mRNA expression of P450 isoforms corresponding with the five studied P450 enzymes in humans. In the healthy subjects, short-term fasting increased oral caffeine clearance by 20% (P = 0.03) and decreased oral S-warfarin clearance by 25% (P < 0.001). In rats, short-term fasting increased mRNA expression of the orthologs of human CYP1A2, CYP2C19, CYP2D6, and CYP3A4 (P < 0.05), and decreased the mRNA expression of the ortholog of CYP2C9 (P < 0.001) compared with the postabsorptive state. These results demonstrate that short-term fasting alters cytochrome P450-mediated drug metabolism in a nonuniform pattern. Therefore, short-term fasting is another factor affecting cytochrome P450-mediated drug metabolism in humans. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Evidence for communality in the primary determinants of CYP74 catalysis and of structural similarities between CYP74 and classical mammalian P450 enzymes.

PubMed

Hughes, Richard K; Yousafzai, Faridoon K; Ashton, Ruth; Chechetkin, Ivan R; Fairhurst, Shirley A; Hamberg, Mats; Casey, Rod

2008-09-01

In silico structural analysis of CYP74C3, a membrane-associated P450 enzyme from the plant Medicago truncatula (barrel medic) with hydroperoxide lyase (HPL) specificity, showed that it had strong similarities to the structural folds of the classical microsomal P450 enzyme from rabbits (CYP2C5). It was not only the secondary structure predictions that supported the analysis but site directed mutagenesis of the substrate interacting residues was also consistent with it. This led us to develop a substrate-binding model of CYP74C3 which predicted three amino acid residues, N285, F287, and G288 located in the putative I-helix and distal haem pocket of CYP74C3 to be in close proximity to the preferred substrate 13-HPOTE. These residues were judged to be in equivalent positions to those identified in SRS-4 of CYP2C5. Significance of the residues and their relevance to the model were further assessed by site directed mutagenesis of the three residues followed by EPR spectroscopic and detailed kinetic investigations of the mutated proteins in the presence and absence of detergent. Although point mutation of the residues had no effect on the haem content of the mutated proteins, significant effects on the spin state equilibrium of the haem iron were noted. Kinetic effects of the mutations, which were investigated using three different substrates, were dramatic in nature. In the presence of detergent with the preferred substrate (13-HPOTE), the catalytic center activities and substrate binding affinities of the mutant proteins were reduced by a factor of 8-32 and 4-12, respectively, compared with wild-type--a two orders of magnitude reduction in catalytic efficiencies. We believe this is the first report where primary determinants of catalysis for any CYP74 enzyme, which are fully consistent with our model, have been identified. Our working model predicts that N285 is close enough to suggest that a hydrogen bond with the peroxy group of the enzyme substrate 13-HPOTE is warranted, whereas significance of F287 may arise from a strong hydrophobic interaction between the alkyl group(s) of the substrate and the phenyl ring of F287. We believe that G288 is crucial because of its size. Any other residue with a relatively bulky side chain will hinder the access of substrate to the active site. The effects of the mutations suggests that subtle protein conformational changes in the putative substrate-binding pocket regulate the formation of a fully active monomer-micelle complex with low-spin haem iron and that structural communication exists between the substrate- and micelle-binding sites of CYP74C3. Conservation in CYP74 sequence alignments suggests that N285, F287, and G288 in CYP74C3 and the equivalent residues at positions in other CYP74 enzymes are likely to be critical to catalysis. To support this we show that G324 in CYP74D4 (Arabidopsis AOS), equivalent to G288 in CYP74C3, is a primary determinant of positional specificity. We suggest that the overall structure of CYP74 enzymes is likely to be very similar to those described for classical P450 monooxygenase enzymes. 2008 Wiley-Liss, Inc.

Evaluation of six proton pump inhibitors as inhibitors of various human cytochromes P450: focus on cytochrome P450 2C19.

PubMed

Zvyaga, Tatyana; Chang, Shu-Ying; Chen, Cliff; Yang, Zheng; Vuppugalla, Ragini; Hurley, Jeremy; Thorndike, Denise; Wagner, Andrew; Chimalakonda, Anjaneya; Rodrigues, A David

2012-09-01

Six proton pump inhibitors (PPIs), omeprazole, lansoprazole, esomeprazole, dexlansoprazole, pantoprazole, and rabeprazole, were shown to be weak inhibitors of cytochromes P450 (CYP3A4, -2B6, -2D6, -2C9, -2C8, and -1A2) in human liver microsomes. In most cases, IC₅₀ values were greater than 40 μM, except for dexlansoprazole and lansoprazole with CYP1A2 (IC₅₀ = ∼8 μM) and esomeprazole with CYP2C8 (IC₅₀ = 31 μM). With the exception of CYP2C19 inhibition by omeprazole and esomeprazole (IC₅₀ ratio, 2.5 to 5.9), there was no evidence for a marked time-dependent shift in IC₅₀ (IC₅₀ ratio, ≤ 2) after a 30-min preincubation with NADPH. In the absence of preincubation, lansoprazole (IC₅₀ = 0.73 μM) and esomeprazole (IC₅₀ = 3.7 μM) were the most potent CYP2C19 inhibitors, followed by dexlansoprazole and omeprazole (IC₅₀ = ∼7.0 μM). Rabeprazole and pantoprazole (IC₅₀ = ≥ 25 μM) were the weakest. A similar ranking was obtained with recombinant CYP2C19. Despite the IC₅₀ ranking, after consideration of plasma levels (static and dynamic), protein binding, and metabolism-dependent inhibition, it is concluded that omeprazole and esomeprazole are the most potent CYP2C19 inhibitors. This was confirmed after the incubation of the individual PPIs with human primary hepatocytes (in the presence of human serum) and by monitoring their impact on diazepam N-demethylase activity at a low concentration of diazepam (2 μM). Data described herein are consistent with reports that PPIs are mostly weak inhibitors of cytochromes P450 in vivo. However, two members of the PPI class (esomeprazole and omeprazole) are more likely to serve as clinically relevant inhibitors of CYP2C19.

Proton pump inhibitors: from CYP2C19 pharmacogenetics to precision medicine.

PubMed

El Rouby, Nihal; Lima, John J; Johnson, Julie A

2018-04-01

Proton Pump inhibitors (PPIs) are commonly used for a variety of acid related disorders. Despite the overall effectiveness and safety profile of PPIs, some patients do not respond adequately or develop treatment related adverse events. This variable response among patients is in part due to genotype variability of CYP2C19, the gene encoding the CYP450 (CYP2C19) isoenzyme responsible for PPIs metabolism. Areas covered: This article provides an overview of the pharmacokinetics and mechanism of action of the currently available PPIs, including the magnitude of CYPC19 contribution to their metabolism. Additionally, the role of CYP2C19 genetic variability in the therapeutic effectiveness or outcomes of PPI therapy is highlighted in details, to provide supporting evidence for the potential value of CYP2C19 genotype-guided approaches to PPI drug therapy. Expert opinion: There is a large body of evidence describing the impact of CYP2C19 variability on PPIs and its potential role in individualizing PPI therapy, yet, CYP2C19 pharmacogenetics has not been widely implemented into clinical practice. More data are needed but CYP2C19 genotype-guided dosing of PPIs is likely to become increasingly common and is expected to improve clinical outcomes, and minimize side effects related to PPIs.

Proton pump inhibitors: from CYP2C19 pharmacogenetics to precision medicine

PubMed Central

El Rouby, Nihal; Lima, John J.; Johnson, Julie A.

2018-01-01

ABSTRACT Introduction: Proton Pump inhibitors (PPIs) are commonly used for a variety of acid related disorders. Despite the overall effectiveness and safety profile of PPIs, some patients do not respond adequately or develop treatment related adverse events. This variable response among patients is in part due to genotype variability of CYP2C19, the gene encoding the CYP450 (CYP2C19) isoenzyme responsible for PPIs metabolism. Areas covered: This article provides an overview of the pharmacokinetics and mechanism of action of the currently available PPIs, including the magnitude of CYPC19 contribution to their metabolism. Additionally, the role of CYP2C19 genetic variability in the therapeutic effectiveness or outcomes of PPI therapy is highlighted in details, to provide supporting evidence for the potential value of CYP2C19 genotype-guided approaches to PPI drug therapy. Expert opinion: There is a large body of evidence describing the impact of CYP2C19 variability on PPIs and its potential role in individualizing PPI therapy, yet, CYP2C19 pharmacogenetics has not been widely implemented into clinical practice. More data are needed but CYP2C19 genotype-guided dosing of PPIs is likely to become increasingly common and is expected to improve clinical outcomes, and minimize side effects related to PPIs. PMID:29620484

Effect of diethyldithiocarbamate (DDC) and ticlopidine on CYP1A2 activity and caffeine metabolism: an in vitro comparative study with human cDNA-expressed CYP1A2 and liver microsomes.

PubMed

Kot, Marta; Daniel, Władysława A

2009-01-01

The aim of the present study was to test the effect of diethyldithiocarbamate (DDC), which is regarded as a cytochrome P450 (CYP) CYP2A6 and CYP2E1 inhibitor, and ticlopidine, an efficient CYP2B6, CYP2C19 and CYP2D6 inhibitor, on the activity of human CYP1A2 and the metabolism of caffeine (1-N-, 3-N- and 7-N-demethylation, and C-8-hydroxylation). The experiment was carried out in vitro using human cDNA-expressed CYP1A2 (Supersomes) and human pooled liver microsomes. The effects of DDC and ticlopidine were compared to those of furafylline (a strong CYP1A2 inhibitor). A comparative in vitro study provides clear evidence that ticlopidine and DDC, applied at concentrations that inhibit the above-mentioned CYP isoforms, potently (as compared to furafylline) inhibit human CYP1A2 and caffeine metabolism, in particular 1-N- and 3-N-demethylation.

CYP2C8 and CYP3A4 are the principal enzymes involved in the human in vitro biotransformation of the insulin secretagogue repaglinide

PubMed Central

Bidstrup, Tanja Busk; Bjørnsdottir, Inga; Sidelmann, Ulla Grove; Thomsen, Mikael Søndergård; Hansen, Kristian Tage

2003-01-01

Aims To identify the principal human cytochrome P450 (CYP) enzyme(s) responsible for the human in vitro biotransformation of repaglinide. Previous experiments have identified CYP3A4 as being mainly responsible for the in vitro metabolism of repaglinide, but the results of clinical investigations have suggested that more than one enzyme may be involved in repaglinide biotransformation. Methods [14C]-Repaglinide was incubated with recombinant CYP and with human liver microsomes (HLM) from individual donors in the presence of inhibitory antibodies specific for individual CYP enzymes. Metabolites, measured by high-performance liquid chromatography (HPLC) with on-line radiochemical detection, were identified by liquid chromatography-mass spectrophotometry (LC-MS) and LC-MS coupled on-line to a nuclear magnetic resonance spectrometer (LC-MS-NMR). Results CYP3A4 and CYP2C8 were found to be responsible for the conversion of repaglinide into its two primary metabolites, M4 (resulting from hydroxylation on the piperidine ring system) and M1 (an aromatic amine). Specific inhibitory monoclonal antibodies against CYP3A4 and CYP2C8 significantly inhibited (> 71%) formation of M4 and M1 in HLM. In a panel of HLM from 12 individual donors formation of M4 and M1 varied from approximately 160–880 pmol min−1 mg−1 protein and from 100–1110 pmol min−1 mg−1 protein, respectively. The major metabolite generated by CYP2C8 was found to be M4. The rate of formation of this metabolite in HLM correlated significantly with paclitaxel 6α-hydroxylation (rs = 0.80; P = 0.0029). Two other minor metabolites were also detected. One of them was M1 and the other was repaglinide hydroxylated on the isopropyl moiety (M0-OH). The rate of formation of M4 in CYP2C8 Supersomes™ was 2.5 pmol min−1 pmol−1 CYP enzyme and only about 0.1 pmol min−1 pmol−1 CYP enzyme in CYP3A4 Supersomes™. The major metabolite generated by CYP3A4 was M1. The rate of formation of this metabolite in HLM correlated significantly with testosterone 6β-hydroxylation (rs = 0.90; P = 0.0002). Three other metabolites were identified, namely, M0-OH, M2 (a dicarboxylic acid formed by oxidative opening of the piperidine ring) and M5. The rate of M1 formation in CYP3A4 Supersomes™ was 1.6 pmol min−1 pmol−1 CYP enzyme but in CYP2C8 Super-somes™ it was only approximately 0.4 pmol min−1 pmol−1 CYP enzyme. Conclusions The results confirm an important role for both CYP3A4 and CYP2C8 in the human in vitro biotransformation of repaglinide. This dual CYP biotransformation may have consequences for the clinical pharmacokinetics and drug-drug interactions involving repaglinide if one CYP pathway has sufficient capacity to compensate if the other is inhibited. PMID:12919179

Relative contribution of rat cytochrome P450 isoforms to the metabolism of caffeine: the pathway and concentration dependence.

PubMed

Kot, Marta; Daniel, Władysława A

2008-04-01

The aim of the present study was to estimate the relative contribution of rat P450 isoforms to the metabolism of caffeine and to assess the usefulness of caffeine as a marker substance for estimating the activity of P450 in rat liver and its potential for pharmacokinetic interactions in pharmacological experiments. The results obtained using rat cDNA-expressed P450s indicated that 8-hydroxylation was the main oxidation pathway of caffeine (70%) in the rat. CYP1A2 was found to be a key enzyme catalyzing 8-hydroxylation (72%) and substantially contributing to 3-N-demethylation (47%) and 1-N-demethylation (37.5%) at a caffeine concentration of 0.1mM (relevant to "the maximum therapeutic concentration in humans"). Furthermore, CYP2C11 considerably contributed to 3-N-demethylation (31%). The CYP2C subfamily (66%) - mainly CYP2C6 (27%) and CYP2C11 (29%) - played a major role in catalyzing 7-N-demethylation. At higher substrate concentrations, the contribution of CYP1A2 to the metabolism of caffeine decreased in favor of CYP2C11 (N-demethylations) and CYP3A2 (mainly 8-hydroxylation). The obtained results were confirmed with liver microsomes (inhibition and correlation studies). Therefore, caffeine may be used as a marker substance for assessing the activity of CYP1A2 in rats, using 8-hydroxylation (but not 3-N-demethylation-like in humans); moreover, caffeine may also be used to simultaneously, preliminarily estimate the activity of CYP2C using 7-N-demethylation as a marker reaction. Hence caffeine pharmacokinetics in rats may be changed by drugs affecting the activity of CYP1A2 and/or CYP2C, e.g. by some antidepressants.

Identification of putative substrates for cynomolgus monkey cytochrome P450 2C8 by substrate depletion assays with 22 human P450 substrates and inhibitors.

PubMed

Hosaka, Shinya; Murayama, Norie; Satsukawa, Masahiro; Uehara, Shotaro; Shimizu, Makiko; Iwasaki, Kazuhide; Iwano, Shunsuke; Uno, Yasuhiro; Yamazaki, Hiroshi

2016-07-01

Cynomolgus monkeys are widely used in drug developmental stages as non-human primate models. Previous studies used 89 compounds to investigate species differences associated with cytochrome P450 (P450 or CYP) function that reported monkey specific CYP2C76 cleared 19 chemicals, and homologous CYP2C9 and CYP2C19 metabolized 17 and 30 human CYP2C9 and/or CYP2C19 substrates/inhibitors, respectively. In the present study, 22 compounds selected from viewpoints of global drug interaction guidances and guidelines were further evaluated to seek potential substrates for monkey CYP2C8, which is highly homologous to human CYP2C8 (92%). Amodiaquine, montelukast, quercetin and rosiglitazone, known as substrates or competitive inhibitors of human CYP2C8, were metabolically depleted by recombinant monkey CYP2C8 at relatively high rates. Taken together with our reported findings of the slow eliminations of amodiaquine and montelukast by monkey CYP2C9, CYP2C19 and CYP2C76, the present results suggest that these at least four chemicals may be good marker substrates for monkey CYP2C8. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2015 John Wiley & Sons, Ltd.

Tamoxifen metabolism predicts drug concentrations and outcome in premenopausal patients with early breast cancer

PubMed Central

Saladores, P; Mürdter, T; Eccles, D; Chowbay, B; Zgheib, N K; Winter, S; Ganchev, B; Eccles, B; Gerty, S; Tfayli, A; Lim, J S L; Yap, Y S; Ng, R C H; Wong, N S; Dent, R; Habbal, M Z; Schaeffeler, E; Eichelbaum, M; Schroth, W; Schwab, M; Brauch, H

2015-01-01

Tamoxifen is the standard-of-care treatment for estrogen receptor-positive premenopausal breast cancer. We examined tamoxifen metabolism via blood metabolite concentrations and germline variations of CYP3A5, CYP2C9, CYP2C19 and CYP2D6 in 587 premenopausal patients (Asians, Middle Eastern Arabs, Caucasian-UK; median age 39 years) and clinical outcome in 306 patients. N-desmethyltamoxifen (DM-Tam)/(Z)-endoxifen and CYP2D6 phenotype significantly correlated across ethnicities (R2: 53%, P<10−77). CYP2C19 and CYP2C9 correlated with norendoxifen and (Z)-4-hydroxytamoxifen concentrations, respectively (P<0.001). DM-Tam was influenced by body mass index (P<0.001). Improved distant relapse-free survival (DRFS) was associated with decreasing DM-Tam/(Z)-endoxifen (P=0.036) and increasing CYP2D6 activity score (hazard ratio (HR)=0.62; 95% confidence interval (CI), 0.43–0.91; P=0.013). Low (<14 nM) compared with high (>35 nM) endoxifen concentrations were associated with shorter DRFS (univariate P=0.03; multivariate HR=1.94; 95% CI, 1.04–4.14; P=0.064). Our data indicate that endoxifen formation in premenopausal women depends on CYP2D6 irrespective of ethnicity. Low endoxifen concentration/formation and decreased CYP2D6 activity predict shorter DRFS. PMID:25091503

Altered metabolism of synthetic cannabinoid JWH-018 by human cytochrome P450 2C9 and variants.

PubMed

Patton, Amy L; Seely, Kathryn A; Yarbrough, Azure L; Fantegrossi, William; James, Laura P; McCain, Keith R; Fujiwara, Ryoichi; Prather, Paul L; Moran, Jeffery H; Radominska-Pandya, Anna

2018-04-06

Synthetic cannabinoids (SCBs), synonymous with 'K2', 'Spice' or 'synthetic marijuana', are psychoactive drugs of abuse that frequently result in clinical effects and toxicity more severe than those classically associated with Δ 9 -tetrahydrocannabinol such as extreme agitation, hallucinations, supraventricular tachycardia, syncope, and seizures. JWH-018 is one of the earliest compounds identified in various SCB products, and our laboratory previously demonstrated that JWH-018 undergoes extensive metabolism by cytochromes P450 (P450), binds to, and activates cannabinoid receptors (CBRs). The major enzyme involved in the metabolism of JWH-018 is CYP2C9, a highly polymorphic enzyme found largely in the intestines and liver, with *1 being designated as the wild type, and *2 and *3 as the two most common variants. Three different major products have been identified in human urine and plasma: JWH-018 (ω)-OH, JWH-018 (ω-1)-OH(R), and JWH-018 (ω-1)-OH(S). The (ω-1)-OH metabolite of JWH-018 is a chiral molecule, and is thus designated as either (ω-1)-OH(R) or (ω-1)-OH(S). Here, in vitro enzyme kinetic assays performed with human recombinant CYP2C9 variants (*1, *2, and *3) revealed that oxidative metabolism by CYP2C9*3 resulted in significantly less formation of (ω)-OH and (ω-1)-OH metabolites. Surprisingly, CYP2C9*2 was roughly 3.6-fold more efficient as the CYP2C9*1 enzyme based on V max /K m , increasing the rate of JWH-018 metabolism and allowed for a much more rapid elimination. These results suggest that genetic polymorphisms of P450 enzymes result in the production of varying levels of biologically active JWH-018 metabolites in some individuals, offering a mechanistic explanation for the diverse clinical toxicity often observed following JWH-018 abuse. Copyright © 2018 Elsevier Inc. All rights reserved.

Frequencies of Functional Polymorphisms in Three Pharmacokinetic Genes of Clinical Interest within the Admixed Puerto Rican Population

PubMed Central

Orengo-Mercado, Carmelo; Nieves, Bianca; López, Lizbeth; Vallés-Ortiz, Nabila; Renta, Jessicca Y.; Santiago-Borrero, Pedro J.; Cadilla, Carmen L.; Duconge, Jorge

2013-01-01

Objective This cross-sectional study was aimed at determining the allele frequencies for the CYP2C19*2, CYP2C19*3, CYP2D6*10 and PON1 (rs662) polymorphisms in the Puerto Rican population. The CYP2C19, CYP2D6 and PON1 genes are known to be associated with functional changes in drug metabolism and activation. Individuals carrying the aforementioned polymorphisms are at a higher risk of suffering from drug-induced adverse events and/ or unresponsiveness from a variety of drugs that includes antidepressants, atypical antipsychotics and antiplatelet compounds. Information on the frequency of these polymorphisms is more commonly found on homogeneous populations, but is scarce in highly heterogeneous populations like Hispanics, as in the case of Puerto Ricans. Method Genotyping was carried out in 100 genomic DNA samples from dried blood spots supplied by the Puerto Rican Newborn Screening program using Taqman® Genotyping Assays. Results The Minor Allele Frequencies (MAF) obtained were 9% for CYP2C19*2 and CYP2D6*10, 50% for PON1 (rs662), while the CYP2C19*3 variant was not detected in our study. Furthermore, Hardy Weinberg equilibrium analysis was assessed as well as a comparison between Puerto Rico and other reference populations using a Z-test for proportions. Conclusion The observed allele and genotype frequencies on these relevant pharmacogenes in Puerto Ricans were more closely related to those early reported in two other reference populations of Americans (Mexicans and Colombians). PMID:24040574

Frequencies of Functional Polymorphisms in Three Pharmacokinetic Genes of Clinical Interest within the Admixed Puerto Rican Population.

PubMed

Orengo-Mercado, Carmelo; Nieves, Bianca; López, Lizbeth; Vallés-Ortiz, Nabila; Renta, Jessicca Y; Santiago-Borrero, Pedro J; Cadilla, Carmen L; Duconge, Jorge

2013-03-27

This cross-sectional study was aimed at determining the allele frequencies for the CYP2C19*2, CYP2C19*3, CYP2D6*10 and PON1 (rs662) polymorphisms in the Puerto Rican population. The CYP2C19, CYP2D6 and PON1 genes are known to be associated with functional changes in drug metabolism and activation. Individuals carrying the aforementioned polymorphisms are at a higher risk of suffering from drug-induced adverse events and/ or unresponsiveness from a variety of drugs that includes antidepressants, atypical antipsychotics and antiplatelet compounds. Information on the frequency of these polymorphisms is more commonly found on homogeneous populations, but is scarce in highly heterogeneous populations like Hispanics, as in the case of Puerto Ricans. Genotyping was carried out in 100 genomic DNA samples from dried blood spots supplied by the Puerto Rican Newborn Screening program using Taqman® Genotyping Assays. The Minor Allele Frequencies (MAF) obtained were 9% for CYP2C19*2 and CYP2D6*10, 50% for PON1 (rs662), while the CYP2C19*3 variant was not detected in our study. Furthermore, Hardy Weinberg equilibrium analysis was assessed as well as a comparison between Puerto Rico and other reference populations using a Z-test for proportions. The observed allele and genotype frequencies on these relevant pharmacogenes in Puerto Ricans were more closely related to those early reported in two other reference populations of Americans (Mexicans and Colombians).

In vitro metabolism of phenytoin in 36 CYP2C9 variants found in the Chinese population.

PubMed

Chen, Lian-Guo; Wang, Zhe; Zhu, Yuan; Xiong, Jian-Hua; Sun, Li-Rong; Dai, Da-Peng; Cai, Jian-Ping; Hu, Guo-Xin

2016-06-25

Cytochrome P450 2C9 (CYP2C9) is an important member of the cytochrome P450 enzyme superfamily, with 57 CYP2C9 allelic variants being previously reported. Recently, we identified 22 novel alleles (*36 -*56 and N418T) in the Han Chinese population. This study aims to assess the catalytic activities of wild-type (CYP2C9*1) and 36 CYP2C9 allelic variants found in the Chinese population toward phenytoin (PHT) in vitro. Insect microsomes expressing CYP2C9*1 and 36 CYP2C9 variants were incubated with 1-200 μM phenytoin for 30 min at 37 °C. Then, these products were extracted and the signal detection was performed by HPLC-MS/MS. The intrinsic clearance (Vmax/Km) values of all variants, with the exception of CYP2C9*2, CYP2C9*11, CYP2C9*23, CYP2C9*29, CYP2C9*34, CYP2C9*38, CYP2C9*44, CYP2C9*46 and CYP2C9*48, were significantly different from CYP2C9*1. CYP2C9*27, *40, *41, *47, *49, *51, *53, *54, *56 and N418T variant exhibited markedly larger values than CYP2C9*1 (>152.8%), whereas 17 variants exhibited smaller values (from 48.6% to 99.9%) due to larger Km and/or smaller Vmax values than CYP2C9*1. The findings suggest that more attention should be paid on subjects carrying these infrequent CYP2C9 alleles when administering phenytoin in clinic. Copyright © 2016 Elsevier Ireland Ltd. All rights reserved.

Identification of a CYP3A form (CYP3A126) in fathead minnow (Pimephales promelas) and characterisation of putative CYP3A enzyme activity.

PubMed

Christen, Verena; Caminada, Daniel; Arand, Michael; Fent, Karl

2010-01-01

Cytochrome P450-dependent monooxygenases (CYPs) are involved in the metabolic defence against xenobiotics. Human CYP3A enzymes metabolise about 50% of all pharmaceuticals in use today. Induction of CYPs and associated xenobiotic metabolism occurs also in fish and may serve as a useful tool for biomonitoring of environmental contamination. In this study we report on the cloning of a CYP3A family gene from fathead minnows (Pimephales promelas), which has been designated as CYP3A126 by the P450 nomenclature committee (GenBank no. EU332792). The cDNA was isolated, identified and characterised by extended inverse polymerase chain reaction (PCR), an alternative to the commonly used method of rapid amplification of cDNA ends. In a fathead minnow cell line we identified a full-length cDNA sequence (1,863 base pairs (bp)) consisting of a 1,536 bp open reading frame encoding a 512 amino acid protein. Genomic analysis of the identified CYP3A isoenzyme revealed a DNA sequence consisting of 13 exons and 12 introns. CYP3A126 is also expressed in fathead minnow liver as demonstrated by reverse transcription PCR. Exposure of fathead minnow (FHM) cells with the CYP3A inducer rifampicin leads to dose-dependent increase in putative CYP3A enzyme activity. In contrast, inhibitory effects of diazepam treatment were observed on putative CYP3A enzyme activity and additionally on CYP3A126 mRNA expression. This indicates that CYP3A is active in FHM cells and that CYP3A126 is at least in part responsible for this CYP3A activity. Further investigations will show whether CYP3A126 is involved in the metabolism of environmental chemicals.

Cyp2c44 epoxygenase is essential for preventing the renal sodium absorption during increasing dietary potassium intake.

PubMed

Sun, Peng; Antoun, Joseph; Lin, Dao-Hong; Yue, Peng; Gotlinger, Katherine H; Capdevila, Jorge; Wang, Wen-Hui

2012-02-01

The aim of this study is to test whether the Cyp2c44 epoxygenase-dependent metabolism of arachidonic acid prevents the hypertensive effect of a high K (HK) intake by inhibiting the epithelial sodium channel (ENaC) activity. A HK intake elevated Cyp2c44 mRNA expression and 11,12-epoxyeicosatrienoic acid levels in the cortical collecting duct in Cyp2c44(+/+) mice (wild-type [wt]). However, an HK intake failed to increase 11,12-epoxyeicosatrienoic acid formation in the cortical collecting ducts of Cyp2c44(-/-) mice. Moreover, increasing K intake enhanced arachidonic acid-induced inhibition of ENaC in the wt but not in Cyp2c44(-/-) mice. In contrast, 11,12-epoxyeicosatrienoic acid, a Cyp2c44 metabolite, inhibited ENaC in the wt and Cyp2c44(-/-) mice. The notion that Cyp2c44 is the epoxygenase responsible for mediating the inhibitory effects of arachidonic acid on ENaC is further suggested by the observation that inhibiting Cyp-epoxygenase increased the whole-cell Na currents in principal cells of wt but not in Cyp2c44(-/-) mice. Feeding mice with an HK diet raised the systemic blood pressures of Cyp2c44(-/-) mice but was without an effect on wt mice. Moreover, application of amiloride abolished the HK-induced hypertension in Cyp2c44(-/-) mice. The HK-induced hypertension of Cyp2c44(-/-) mice was accompanied by decreasing 24-hour urinary Na excretion and increasing the plasma Na concentration, and the effects were absent in wt mice. In contrast, disruption of the Cyp2c44 gene did not alter K excretion. We conclude that Cyp2c44 epoxygenase mediates the inhibitory effect of arachidonic acid on ENaC and that Cyp2c44 functions as an HK-inducible antihypertensive enzyme responsible for inhibiting ENaC activity and Na absorption in the aldosterone-sensitive distal nephron.

Omeprazole hydroxylation is inhibited by a single dose of moclobemide in homozygotic EM genotype for CYP2C19.

PubMed

Cho, Joo-Youn; Yu, Kyung-Sang; Jang, In-Jin; Yang, Byung-Hwan; Shin, Sang-Goo; Yim, Dong-Seok

2002-04-01

The pharmacokinetics of omeprazole and its metabolites in healthy subjects were evaluated to determine if a single dose of moclobemide inhibited CYP2C19 activity. Sixteen volunteers, of whom eight were extensive metabolizers (EM) and eight were poor metabolizers for CYP2C19, participated in two studies. Venous blood samples were collected for 24 h after oral ingestion of 40 mg omeprazole with or without 300 mg moclobemide coadministration. The pharmacokinetic change of omeprazole, omeprazole sulphone and 5-hydroxyomeprazole concentrations were assessed to test for an interaction between omeprazole and moclobemide. The coadministration of moclobemide in EMs approximately doubled the mean AUC (from 1834 to 3760 ng ml(-1) h) and C(max) (from 987 to 1649 ng ml(-1)) of omeprazole, and increased the AUC of omeprazole sulphone without changing AUC ratio of omeprazole to omeprazole sulphone. Moclobemide coadministration more than doubled the AUC ratio of omeprazole to 5-hydroxyomeprazole (from 2.5 to 5.3) in EMs, too. There was a significant decrease in Cmax and AUC of 5-hydroxyomeprazole in PMs but no significant changes were seen in the results for omeprazole and omeprazole sulphone AUCs. A single dose of moclobemide resulted in significant suppression of CYP2C19 activity in EMs. We conclude that physicians prescribing moclobemide should pay attention to its pharmacokinetic interactions even on the first day of coadministration with CYP2C19 substrates.

Structural comparison of cytochromes P450 2A6, 2A13, and 2E1 with pilocarpine

DOE Office of Scientific and Technical Information (OSTI.GOV)

DeVore, Natasha M.; Meneely, Kathleen M.; Bart, Aaron G.

2013-11-20

Human xenobiotic-metabolizing cytochrome P450 (CYP) enzymes can each bind and monooxygenate a diverse set of substrates, including drugs, often producing a variety of metabolites. Additionally, a single ligand can interact with multiple CYP enzymes, but often the protein structural similarities and differences that mediate such overlapping selectivity are not well understood. Even though the CYP superfamily has a highly canonical global protein fold, there are large variations in the active site size, topology, and conformational flexibility. We have determined how a related set of three human CYP enzymes bind and interact with a common inhibitor, the muscarinic receptor agonist drugmore » pilocarpine. Pilocarpine binds and inhibits the hepatic CYP2A6 and respiratory CYP2A13 enzymes much more efficiently than the hepatic CYP2E1 enzyme. To elucidate key residues involved in pilocarpine binding, crystal structures of CYP2A6 (2.4 {angstrom}), CYP2A13 (3.0 {angstrom}), CYP2E1 (2.35 {angstrom}), and the CYP2A6 mutant enzyme, CYP2A6 I208S/I300F/G301A/S369G (2.1 {angstrom}) have been determined with pilocarpine in the active site. In all four structures, pilocarpine coordinates to the heme iron, but comparisons reveal how individual residues lining the active sites of these three distinct human enzymes interact differently with the inhibitor pilocarpine.« less

A frameshift variant of CYP2C8 was identified in a patient who suffered from rhabdomyolysis after administration of cerivastatin.

PubMed

Ishikawa, Chikako; Ozaki, Hiroshi; Nakajima, Toshiaki; Ishii, Toshihiro; Kanai, Saburo; Anjo, Saeko; Shirai, Kohji; Inoue, Ituro

2004-01-01

A hypercholesterolemic patient medicated with cerivastatin for 22 days resulted in acute rhabdomyolysis. CYP2C8 and CYP3A4 are the major enzymes responsible for the metabolism of cerivastatin, and a transporter, OATP2, contributes to uptake of cerivastatin to the liver. In this study, the patient's DNA was sequenced in order to identify a variant that would lead to the adverse effect of cerivastatin. Three nucleotide variants, 475delA, G874C, and T1551C, were found in the exons of CYP2C8. The patient was homozygous for 475delA variant that leads to frameshift and premature termination. Accordingly, the patient is most likely lacking the enzyme activity. The patient's children were both heterozygous for the mutation. The patient had three nucleotide variants in exon 4 (A388G) and exon 5 (C571T and C597T) of OATP2 that were all heterozygous. No nucleotide variation in the exons of CYP3A4 was identified. To our knowledge, this is the first report showing that the adverse effect of cerivastatin might be caused by the genetic variant of CYP2C8.

Genetic variation in biotransformation enzymes, air pollution exposures, and risk of spina bifida.

PubMed

Padula, Amy M; Yang, Wei; Schultz, Kathleen; Lurmann, Fred; Hammond, S Katharine; Shaw, Gary M

2018-05-01

Spina bifida is a birth defect characterized by incomplete closure of the embryonic neural tube. Genetic factors as well as environmental factors have been observed to influence risks for spina bifida. Few studies have investigated possible gene-environment interactions that could contribute to spina bifida risk. The aim of this study is to examine the interaction between gene variants in biotransformation enzyme pathways and ambient air pollution exposures and risk of spina bifida. We evaluated the role of air pollution exposure during pregnancy and gene variants of biotransformation enzymes from bloodspots and buccal cells in a California population-based case-control (86 cases of spina bifida and 208 non-malformed controls) study. We considered race/ethnicity and folic acid vitamin use as potential effect modifiers and adjusted for those factors and smoking. We observed gene-environment interactions between each of the five pollutants and several gene variants: NO (ABCC2), NO 2 (ABCC2, SLC01B1), PM 10 (ABCC2, CYP1A1, CYP2B6, CYP2C19, CYP2D6, NAT2, SLC01B1, SLC01B3), PM 2.5 (CYP1A1 and CYP1A2). These analyses show positive interactions between air pollution exposure during early pregnancy and gene variants associated with metabolizing enzymes. These exploratory results suggest that some individuals based on their genetic background may be more susceptible to the adverse effects of pollution. © 2018 Wiley Periodicals, Inc.

Effects of bisphenol A on the expression of cytochrome P450 aromatase (CYP19) in human fetal osteoblastic and granulosa cell-like cell lines.

PubMed

Watanabe, Masatada; Ohno, Shuji; Nakajin, Shizuo

2012-04-05

The effects of bisphenol A (BPA), an endocrine disruptor, on aromatase (CYP19) expression in human osteoblastic (SV-HFO) and ovarian granulosa-like (KGN) cell lines were examined. CYP19 enzyme activity was suppressed in the presence of BPA in a dose-dependent fashion in both cell lines. CYP19 gene transcript expression, as well as activities of promoter I.4 in SV-HFO and promoter II in KGN, was down-regulated by BPA, suggesting that BPA affects CYP19 at the gene-expression level. These data and the previous finding that BPA induced the down-regulation of promoter I.1 activity within the human placental cell line suggest that there may be a conserved signaling pathway that down-regulates CYP19 expression in response to BPA in both cell lines. Additionally, differences between promoter I.4 and II suggest that there may be cell- and promoter-specific down-regulating mechanisms downstream from the actions of BPA. Copyright © 2012 Elsevier Ireland Ltd. All rights reserved.

Isoform-specific regulation of cytochrome P450 expression and activity by estradiol in female rats

PubMed Central

Choi, Su-Young; Fischer, Liam; Yang, Kyunghee; Chung, Hyejin; Jeong, Hyunyoung

2011-01-01

Estradiol (E2) is the major endogenous estrogen, and its plasma concentration increases up to 100-fold during pregnancy in humans. Accumulating evidence suggests that an elevated level of E2 may influence hepatic drug metabolism, potentially being responsible for altered drug metabolism during pregnancy. We characterized effects of E2 on expression and activities of cytochrome P450 enzymes (CYPs) in an in vivo system using rats. To this end, female rats were treated with estradiol benzoate (EB) or known CYP inducers. Liver tissues were obtained after 5 days of treatment, and mRNA and protein expression levels as well as activities of major hepatic CYPs were determined by qRT-PCR, immunoblot, and microsomal assay. E2 increased CYP1A2 expression and activity to a smaller extent than β-naphthoflavone did. E2 also enhanced CYP2C expression (CYP2C6, CYP2C7, and CYP2C12) to levels comparable to those observed by phenobarbital. E2 upregulated CYP3A9 expression, while expression of CYP3A1 was downregulated. Expression of hepatic nuclear receptors (PXR and CAR) and the obligate redox partner of CYPs (POR) was downregulated in EB-treated rats, suggesting their potential involvement in regulation of CYP expression and activity by E2. In summary, in female rats E2 regulates expression of hepatic CYPs in a CYP isoform-specific manner although the directional changes are different from those clinically observed during human pregnancy. Further study is warranted to determine whether the changes in drug metabolism during human pregnancy are attributable to involvement of hormones other than E2. PMID:21219883

Size- and time-dependent alteration in metabolic activities of human hepatic cytochrome P450 isozymes by gold nanoparticles via microsomal coincubations

NASA Astrophysics Data System (ADS)

Ye, Meiling; Tang, Ling; Luo, Mengjun; Zhou, Jing; Guo, Bin; Liu, Yangyuan; Chen, Bo

2014-11-01

Nano-sized particles are known to interfere with drug-metabolizing cytochrome P450 (CYP) enzymes, which can be anticipated to be a potential source of unintended adverse reactions, but the mechanisms underlying the inhibition are still not well understood. Herein we report a systematic investigation of the impacts of gold nanoparticles (AuNPs) on five major CYP isozymes under in vitro incubations of human liver microsomes (HLMs) with tannic acid (TA)-stabilized AuNPs in the size range of 5 to 100 nm. It is found that smaller AuNPs show more pronounced inhibitory effects on CYP2C9, CYP2C19, CYP2D6, and CYP3A4 in a dose-dependent manner, while 1A2 is the least susceptible to the AuNP inhibition. The size- and dose-dependent CYP-specific inhibition and the nonspecific drug-nanogold binding in the coincubation media can be significantly reduced by increasing the concentration ratio of microsomal proteins to AuNPs, probably via a noncompetitive mode. Remarkably, AuNPs are also found to exhibit a slow time-dependent inactivation of 2D6 and 3A4 in a β-nicotinamide adenine dinucleotide 2'-phosphate reduced tetrasodium salt hydrate (NADPH)-independent manner. During microsomal incubations, UV-vis spectroscopy, dynamic light scattering, and zeta-potential measurements were used to monitor the changes in particle properties under the miscellaneous AuNP/HLM/CYP dispersion system. An improved stability of AuNPs by mixing HLM with the gold nanocolloid reveals that the stabilization via AuNP-HLM interactions may occur on a faster time scale than the salt-induced nanoaggregation by incubation in phosphate buffer. The results suggest that the AuNP induced CYP inhibition can be partially attributed to its adhesion onto the enzymes to alter their structural conformations or onto the HLM membrane therefore impairing the integral membrane proteins. Additionally, AuNPs likely block the substrate pocket on the CYP surface, depending on both the particle characteristics and the structural diversity of the isozymes. These findings may represent additional mechanisms for the differential inhibitory effects arising from the coincubated AuNPs on the metabolic activities of the hepatic CYP isozymes.

Metabolism of hyperforin, the active constituent of St. John's wort, in human liver microsomes.

PubMed

Hokkanen, Juho; Tolonen, Ari; Mattila, Sampo; Turpeinen, Miia

2011-02-14

The metabolism of hyperforin, one of the pharmacologically most active components of St. John's wort (Hypericum perforatum), was characterized in vitro using human liver microsomes and recombinant heterologously expressed P450 enzymes. A total of 57 hyperforin metabolites were detected. Of those, six were identified as monohydroxylations (M1-M6), while the others were formed via two or more hydroxylation reactions, via dehydrogenation, or by combinations of these reactions. A combined approach of cDNA-expressed recombinant CYPs, CYP-selective chemical inhibitors and correlation with CYP-specific marker activities indicated a central role of the CYP2C and CYP3A families in the metabolism of hyperforin. In addition, hyperforin was found to inhibit CYP2D6 and CYP3A4 model activities quite potently. Copyright © 2010 Elsevier B.V. All rights reserved.

Effect of gamma-oryzanol on cytochrome P450 activities in human liver microsomes.

PubMed

Umehara, Ken; Shimokawa, Yoshihiko; Miyamoto, Gohachiro

2004-07-01

The effects of gamma-oryzanol, a drug mainly used for the treatment of hyperlipidaemia, on several cytochrome P450 (CYP) specific reactions in human liver microsomes were investigated to predict drug interactions with gamma-oryzanol in vivo from in vitro data. The following eight CYP catalytic reactions were used in this study: CYP1A1/2-mediated 7-ethoxyresorufin O-deethylation, CYP2A6-mediated coumarin 7-hydroxylation, CYP2B6-mediated 7-benzyloxyresorufin O-debenzylation, CYP2C8/9-mediated tolbutamide methylhydroxylation, CYP2C19-mediated S-mephenytoin 4'-hydroxylation, CYP2D6-mediated bufuralol 1'-hydroxylation, CYP2E1-mediated chlorzoxazone 6-hydroxylation, and CYP3A4-mediated testosterone 6beta-hydroxylation. gamma-Oryzanol had little inhibitory effects on CYP activities, indicating that this compound would not be expected to cause clinically significant interactions with other CYP-metabolized drugs at expected therapeutic concentrations.

Induction of CYP1A1 and CYP1B1 by benzo(k)fluoranthene and benzo(a)pyrene in T-47D human breast cancer cells: Roles of PAH interactions and PAH metabolites

DOE Office of Scientific and Technical Information (OSTI.GOV)

Spink, David C.; Wu, Susan J.; Spink, Barbara C.

2008-02-01

The interactions of polycyclic aromatic hydrocarbons (PAH) and cytochromes P450 (CYP) are complex; PAHs are enzyme inducers, substrates, and inhibitors. In T-47D breast cancer cells, exposure to 0.1 to 1 {mu}M benzo(k)fluoranthene (BKF) induced CYP1A1/1B1-catalyzed 17{beta}-estradiol (E{sub 2}) metabolism, whereas BKF levels greater than 1 {mu}M inhibited E{sub 2} metabolism. Time course studies showed that induction of CYP1-catalyzed E{sub 2} metabolism persisted after the disappearance of BKF or co-exposed benzo(a)pyrene, suggesting that BKF metabolites retaining Ah receptor agonist activity were responsible for prolonged CYP1 induction. BKF metabolites were shown, through the use of ethoxyresorufin O-deethylase and CYP1A1-promoter-luciferase reporter assays tomore » induce CYP1A1/1B1 in T-47D cells. Metabolites formed by oxidation at the C-2/C-3 region of BKF had potencies for CYP1 induction exceeding those of BKF, whereas C-8/C-9 oxidative metabolites were somewhat less potent than BKF. The activities of expressed human CYP1A1 and 1B1 with BKF as substrate were investigated by use of HPLC with fluorescence detection, and by GC/MS. The results showed that both enzymes efficiently catalyzed the formation of 3-, 8-, and 9-OHBKF from BKF. These studies indicate that the inductive effects of PAH metabolites as potent CYP1 inducers are likely to be additional important factors in PAH-CYP interactions that affect metabolism and bioactivation of other PAHs, ultimately modulating PAH toxicity and carcinogenicity.« less

Genetic and structural analyses of cytochrome P450 hydroxylases in sex hormone biosynthesis: Sequential origin and subsequent coevolution.

PubMed

Goldstone, Jared V; Sundaramoorthy, Munirathinam; Zhao, Bin; Waterman, Michael R; Stegeman, John J; Lamb, David C

2016-01-01

Biosynthesis of steroid hormones in vertebrates involves three cytochrome P450 hydroxylases, CYP11A1, CYP17A1 and CYP19A1, which catalyze sequential steps in steroidogenesis. These enzymes are conserved in the vertebrates, but their origin and existence in other chordate subphyla (Tunicata and Cephalochordata) have not been clearly established. In this study, selected protein sequences of CYP11A1, CYP17A1 and CYP19A1 were compiled and analyzed using multiple sequence alignment and phylogenetic analysis. Our analyses show that cephalochordates have sequences orthologous to vertebrate CYP11A1, CYP17A1 or CYP19A1, and that echinoderms and hemichordates possess CYP11-like but not CYP19 genes. While the cephalochordate sequences have low identity with the vertebrate sequences, reflecting evolutionary distance, the data show apparent origin of CYP11 prior to the evolution of CYP19 and possibly CYP17, thus indicating a sequential origin of these functionally related steroidogenic CYPs. Co-occurrence of the three CYPs in early chordates suggests that the three genes may have coevolved thereafter, and that functional conservation should be reflected in functionally important residues in the proteins. CYP19A1 has the largest number of conserved residues while CYP11A1 sequences are less conserved. Structural analyses of human CYP11A1, CYP17A1 and CYP19A1 show that critical substrate binding site residues are highly conserved in each enzyme family. The results emphasize that the steroidogenic pathways producing glucocorticoids and reproductive steroids are several hundred million years old and that the catalytic structural elements of the enzymes have been conserved over the same period of time. Analysis of these elements may help to identify when precursor functions linked to these enzymes first arose. Copyright © 2015 Elsevier Inc. All rights reserved.

Polymorphisms of CYP1A2 and CYP2A6 activity: phenotypes and the effect of age and sex in a Nigerian population.

PubMed

Adehin, Ayorinde; Bolaji, Oluseye O

2015-09-01

CYP1A2 and CYP2A6 are polymorphic enzymes that metabolise several compounds of clinical importance. This study investigated the prevalent phenotypes of these enzymes and the influence of age and sex on enzyme activity in a Nigerian population. Caffeine (110 mg) was administered to each of 129 healthy, unrelated subjects (85 males and 44 females) who were non-smokers. Urine voided within 7 h after caffeine administration was collected for a high performance liquid chromatographic assay of caffeine (137X), 1,7-dimethyluric acid (17U) and 1,7-dimethylxanthine (17X). CYP1A2 activity was measured as a ratio of (17U+17X) to 137X, while 17U/17X served as marker for CYP2A6. Transformed data were analysed and the influences of age and sex on activity were also determined. Distribution of CYP1A2 activity in the population was bimodal with a mean±SD of 0.82±0.41, while that of CYP2A6 was trimodal with a mean±SD activity of 0.27±0.42 of the log-transformed urinary molar ratio of metabolites. The influences of age and sex on enzyme activity for both CYP1A2 and CYP2A6 were not significant (p>0.05). The study established the prevalence of polymorphism in phenotypes of CYP1A2 and CYP2A6 activity in the Nigerian population, but no influence of age and sex on enzyme activity was observed in this population.

Omeprazole hydroxylation is inhibited by a single dose of moclobemide in homozygotic EM genotype for CYP2C19

PubMed Central

Cho, Joo-Youn; Yu, Kyung-Sang; Jang, In-Jin; Yang, Byung-Hwan; Shin, Sang-Goo; Yim, Dong-Seok

2002-01-01

Aims The pharmacokinetics of omeprazole and its metabolites in healthy subjects were evaluated to determine if a single dose of moclobemide inhibited CYP2C19 activity. Methods Sixteen volunteers, of whom eight were extensive metabolizers (EM) and eight were poor metabolizers for CYP2C19, participated in two studies. Venous blood samples were collected for 24 h after oral ingestion of 40 mg omeprazole with or without 300 mg moclobemide coadministration. The pharmacokinetic change of omeprazole, omeprazole sulphone and 5-hydroxyomeprazole concentrations were assessed to test for an interaction between omeprazole and moclobemide. Results The coadministration of moclobemide in EMs approximately doubled the mean AUC (from 1834 to 3760 ng ml−1 h) and Cmax (from 987 to 1649 ng ml−1) of omeprazole, and increased the AUC of omeprazole sulphone without changing AUC ratio of omeprazole to omeprazole sulphone. Moclobemide coadministration more than doubled the AUC ratio of omeprazole to 5-hydroxyomeprazole (from 2.5 to 5.3) in EMs, too. There was a significant decrease in Cmax and AUC of 5-hydroxyomeprazole in PMs but no significant changes were seen in the results for omeprazole and omeprazole sulphone AUCs. Conclusions A single dose of moclobemide resulted in significant suppression of CYP2C19 activity in EMs. We conclude that physicians prescribing moclobemide should pay attention to its pharmacokinetic interactions even on the first day of coadministration with CYP2C19 substrates. PMID:11966672

Effect of Ginkgo biloba extract on procarcinogen-bioactivating human CYP1 enzymes: Identification of isorhamnetin, kaempferol, and quercetin as potent inhibitors of CYP1B1

DOE Office of Scientific and Technical Information (OSTI.GOV)

Chang, Thomas K.H.; Chen Jie; Yeung, Eugene Y.H.

2006-05-15

In the present study, we investigated the effect of Ginkgo biloba extracts and some of its individual constituents on the catalytic activity of human cytochrome P450 enzymes CYP1B1, CYP1A1, and CYP1A2. G. biloba extract of known abundance of terpene trilactones and flavonol glycosides inhibited 7-ethoxyresorufin O-dealkylation catalyzed by human recombinant CYP1B1, CYP1A1, and CYP1A2, and human liver microsomes, with apparent K {sub i} values of 2 {+-} 0.3, 5 {+-} 0.5, 16 {+-} 1.4, and 39 {+-} 1.2 {mu}g/ml (mean {+-} SE), respectively. In each case, the mode of inhibition was of the mixed type. Bilobalide, ginkgolides A, B, C,more » and J, quercetin 3-O-rutinoside, kaempferol 3-O-rutinoside, and isorhamentin 3-O-rutinoside were not responsible for the inhibition of CYP1 enzymes by G. biloba extract, as determined by experiments with these individual chemicals at the levels present in the extract. In contrast, the aglycones of quercetin, kaempferol, and isorhamentin inhibited CYP1B1, CYP1A1, and CYP1A2. Among the three flavonol aglycones, isorhamentin was the most potent in inhibiting CYP1B1 (apparent K {sub i} = 3 {+-} 0.1 nM), whereas quercetin was the least potent in inhibiting CYP1A2 (apparent K {sub i} 418 {+-} 50 nM). The mode of inhibition was competitive, noncompetitive, or mixed, depending on the enzyme and the flavonol. G. biloba extract also reduced benzo[a]pyrene hydroxylation, and the effect was greater with CYP1B1 than with CYP1A1 as the catalyst. Overall, our novel findings indicate that G. biloba extract and the flavonol aglycones isorhamnetin, kaempferol, and quercetin preferentially inhibit the in vitro catalytic activity of human CYP1B1.« less

Identification of the rat liver cytochrome P450 enzymes involved in the metabolism of the calcium channel blocker dipfluzine hydrochloride.

PubMed

Guo, Wei; Shi, Xiaowei; Wang, Wei; Zhang, Weili; Li, Junxia

2014-11-01

This study aimed to identify the specific cytochrome P450 (CYP450) enzymes involved in the metabolism of dipfluzine hydrochloride using the combination of a chemical inhibition study, a correlation analysis and a panel of recombinant rat CYP450 enzymes. The incubation of Dip with rat liver microsomes yielded four metabolites, which were identified by liquid chromatography-coupled tandem mass spectrometry (LC/MS/MS). The results from the assays involving eight selective inhibitors indicated that CYP3A and CYP2A1 contributed most to the metabolism of Dip, followed by CYP2C11, CYP2E1 and CYP1A2; however, CYP2B1, CYP2C6 and CYP2D1 did not contribute to the formation of the metabolites. The results of the correlation analysis and the assays involving the recombinant CYP450 enzymes further confirmed the above results and concluded that CYP3A2 contributed more than CYP3A1. The results will be valuable in understanding drug-drug interactions when Dip is coadministered with other drugs. Copyright © 2014 Elsevier B.V. All rights reserved.

Distribution of CYP2D6 and CYP2C19 Polymorphisms Associated with Poor Metabolizer Phenotype in Five Amerindian Groups and Western Mestizos from Mexico

PubMed Central

Salazar-Flores, Joel; Torres-Reyes, Luis A.; Martínez-Cortés, Gabriela; Rubi-Castellanos, Rodrigo; Sosa-Macías, Martha; Muñoz-Valle, José F.; González-González, César; Ramírez, Angélica; Román, Raquel; Méndez, José L.; Barrera, Andrés; Torres, Alfredo; Medina, Rafael

2012-01-01

Background: The distribution of polymorphisms in the CYP2D6 and CYP2C19 genes allows inferring the potential risk for specific adverse drug reactions and lack of therapeutic effects in humans. This variability shows differences among human populations. The aim of this study was to analyze single-nucleotide polymorphisms related to a poor metabolizer (PM) phenotype in nonpreviously studied Amerindian groups and Mestizos (general admixed population) from Mexico. Methods: We detected by SNaPshot® different polymorphisms located in CYP2D6 (*3, *4, *6, *7, and *8) and CYP2C19 (*2, *3, *4 and *5) in western Mestizos (n=145) and five Amerindian groups from Mexico: Tarahumaras from the North (n=88); Purépechas from the Center (n=101); and Tojolabales (n=68), Tzotziles (n=88), and Tzeltales (n=20) from the Southeast. Genotypes were observed by capillary electrophoresis. The genetic relationships among these populations were estimated based on these genes. Results and Discussion: The wild-type allele (*1) of both genes was predominant in the Mexican populations studied. The most widely observed alleles were CYP2C19*2 (range, 0%–31%) and CYP2D6*4 (range, 1.2%–7.3%), whereas CYP2D6*3 was exclusively detected in Mestizos. Conversely, CYP2C19*4 and *5, as well as CYP2D6*3, *6, *7, and *8, were not observed in the majority of the Mexican populations. The Tarahumaras presented a high frequency of the allele CYP2C19*2 (31%) and of homozygotes *2/*2 (10.7%), which represent a high frequency of potentially PM phenotypes in this Amerindian group. The genetic distances showed high differentiation of Tarahumaras (principally for CYP2C19 gene). In general, a relative proximity was observed between most of the Amerindian, Mexican-Mestizo, and Latin-American populations. Conclusion: In general, the wild-type allele (*1) predominates in Mexican populations, outlining a relatively homogeneous distribution for CYP2C19 and CYP2D6. The exception is the Tarahumara group that displays a potentially increased risk for adverse reactions to CYP2C19-metabolized drugs. PMID:22913530

CYP2C9 Genotype vs. Metabolic Phenotype for Individual Drug Dosing—A Correlation Analysis Using Flurbiprofen as Probe Drug

PubMed Central

Vogl, Silvia; Lutz, Roman W.; Schönfelder, Gilbert; Lutz, Werner K.

2015-01-01

Currently, genotyping of patients for polymorphic enzymes responsible for metabolic elimination is considered a possibility to adjust drug dose levels. For a patient to profit from this procedure, the interindividual differences in drug metabolism within one genotype should be smaller than those between different genotypes. We studied a large cohort of healthy young adults (283 subjects), correlating their CYP2C9 genotype to a simple phenotyping metric, using flurbiprofen as probe drug. Genotyping was conducted for CYP2C9*1, *2, *3. The urinary metabolic ratio MR (concentration of CYP2C9-dependent metabolite divided by concentration of flurbiprofen) determined two hours after flurbiprofen (8.75 mg) administration served as phenotyping metric. Linear statistical models correlating genotype and phenotype provided highly significant allele-specific MR estimates of 0.596 for the wild type allele CYP2C9*1, 0.405 for CYP2C9*2 (68 % of wild type), and 0.113 for CYP2C9*3 (19 % of wild type). If these estimates were used for flurbiprofen dose adjustment, taking 100 % for genotype *1/*1, an average reduction to 84 %, 60 %, 68 %, 43 %, and 19 % would result for genotype *1/*2, *1/*3, *2/*2, *2/*3, and *3/*3, respectively. Due to the large individual variation within genotypes with coefficients of variation ≥ 20 % and supposing the normal distribution, one in three individuals would be out of the average optimum dose by more than 20 %, one in 20 would be 40 % off. Whether this problem also applies to other CYPs and other drugs has to be investigated case by case. Our data for the given example, however, puts the benefit of individual drug dosing to question, if it is exclusively based on genotype. PMID:25775139

CYP3A4 and CYP3A5 catalyse the conversion of the N-methyl-D-aspartate (NMDA) antagonist CJ-036878 to two novel dimers.

PubMed

Emoto, C; Nishida, H; Hirai, H; Iwasaki, K

2007-12-01

CJ-036878, N-(3-phenethoxybenzyl)-4-hydroxybenzamide, was developed as an antagonist of the N-methyl-D-aspartate receptor NR2B subunit. Two dimeric metabolites, CJ-047710 and CJ-047713, were identified from the incubation mixture with CJ-036878 in human liver microsomes (HLM). The identification of the enzymes involved in the formation of these dimeric metabolites was investigated in the current study. Inhibition of the formation of CJ-047710 and CJ-047713 in pooled HLM by 1-aminobenztriazole, SKF-525A, and ketoconazole were observed. Ketoconazole played a significant role in inhibiting formation of these two metabolites in a concentration-dependent manner. Recombinant CYP3A4 and CYP3A5 exhibited a markedly high activity toward the formation of CJ-047710 and CJ-047713 from CJ-036878, but the contribution of other CYP enzymes to these formations was at a very low level or negligible. The formation of CJ-047710 and CJ-047713 in pooled HLM, CYP3A4, and CYP3A5 showed sigmoid characteristics. S50 values for CJ-047710 and CJ-047713 formation in HLM were almost equivalent with those for CYP3A4 and CYP3A5. For the CYP3A enzymes, maximal clearance due to auto-activation values for CJ-047710 and CJ-047713 formation catalysed by CYP3A5 were 3.6- and 3.1-fold higher than those catalysed by CYP3A4. This is the first report that shows both CYP3A4 and CYP3A5 simultaneously contribute to dimerization through oxidative C-C and C-O coupling reactions.

Stereoselective metabolism of endosulfan by human liver microsomes and human cytochrome P450 isoforms.

PubMed

Lee, Hwa-Kyung; Moon, Joon-Kwan; Chang, Chul-Hee; Choi, Hoon; Park, Hee-Won; Park, Byeoung-Soo; Lee, Hye-Suk; Hwang, Eul-Chul; Lee, Young-Deuk; Liu, Kwang-Hyeon; Kim, Jeong-Han

2006-07-01

Endosulfan (6,7,8,9,10,10-hexachloro-1,5,5a,6,9,9a-hexahydro-6,9-methano-2,3,4-benzo(e)dioxathiepin-3-oxide) is a broad-spectrum chlorinated cyclodiene insecticide. This study was performed to elucidate the stereoselective metabolism of endosulfan in human liver microsomes and to characterize the cytochrome P450 (P450) enzymes that are involved in the metabolism of endosulfan. Human liver microsomal incubation of endosulfan in the presence of NADPH resulted in the formation of the toxic metabolite, endosulfan sulfate. The intrinsic clearances (CL(int)) of endosulfan sulfate from beta-endosulfan were 3.5-fold higher than those from alpha-endosulfan, suggesting that beta-endosulfan would be cleared more rapidly than alpha-endosulfan. Correlation analysis between the known P450 enzyme activities and the rate of the formation of endosulfan sulfate in the 14 human liver microsomes showed that alpha-endosulfan metabolism is significantly correlated with CYP2B6-mediated bupropion hydroxylation and CYP3A-mediated midazolam hydroxylation, and that beta-endosulfan metabolism is correlated with CYP3A activity. The P450 isoform-selective inhibition study in human liver microsomes and the incubation study of cDNA-expressed enzymes also demonstrated that the stereoselective sulfonation of alpha-endosulfan is mediated by CYP2B6, CYP3A4, and CYP3A5, and that that of beta-endosulfan is transformed by CYP3A4 and CYP3A5. The total CL(int) values of endosulfan sulfate formation catalyzed by CYP3A4 and CYP3A5 were consistently higher for beta-endosulfan than for the alpha-form (CL(int) of 0.67 versus 10.46 microl/min/pmol P450, respectively). CYP2B6 enantioselectively metabolizes alpha-endosulfan, but not beta-endosulfan. These findings suggest that the CYP2B6 and CYP3A enzymes are major enzymes contributing to the stereoselective disposition of endosulfan.

A comparison of the acid-inhibitory effects of esomeprazole and rabeprazole in relation to pharmacokinetics and CYP2C19 polymorphism.

PubMed

Hunfeld, N G; Touw, D J; Mathot, R A; van Schaik, R H; Kuipers, E J

2012-04-01

Esomeprazole and rabeprazole are metabolised in the liver by means of the CYP2C19 enzyme, which has several functional genetic polymorphisms. Among Caucasians, 70% of the population has a fast metaboliser phenotype, 25-30% an intermediate and 2-5% a slow metaboliser phenotype. It is unknown whether different PPIs are affected to the same extent by these phenotypic differences. To compare the acid-inhibitory effects of esomeprazole 40 mg and rabeprazole 20 mg in relation to CYP2C19 genotype and pharmacokinetics. Eighteen healthy Helicobacter pylori-negative Caucasian subjects with CYP2C19*2-*6 and *17 genotype were included in a randomised investigator-blinded crossover study with esomeprazole 40 mg and rabeprazole 20 mg. Intragastric 24-h pH-monitoring was performed on days 0, 1 and 5 of oral dosing. Onset of acid inhibition during the first 4 h after administration did not differ significantly between PPIs. During the upright period, the proportion of time with pH >4 was significantly higher with esomeprazole compared to rabeprazole (52.2 vs. 40.3%, P = 0.003). At day 1 and 5, acid inhibition was significantly greater with esomeprazole than with rabeprazole (median intragastric pH: day 1: 3.7 vs. 3.0, P = 0.008; day 5: 4.7 vs. 3.8, P < 0.001; percentage of time pH >4: day 1: 45 vs. 39%, P = 0.054; day 5: 65 vs. 48%, P < 0.001). Differences in acid inhibition between wt/wt and wt/*2 genotype were significant for both PPIs. Once-daily dosing with esomeprazole 40 mg provides a more effective and faster acid-inhibitory effect than rabeprazole 20 mg. The acid-inhibitory effect of esomeprazole and rabeprazole are both influenced by CYP2C19 polymorphism. © 2012 Blackwell Publishing Ltd.

The effects of antiepileptic inducers in neuropsychopharmacology, a neglected issue. Part II: Pharmacological issues and further understanding.

PubMed

de Leon, Jose

2015-01-01

The literature on inducers in epilepsy and bipolar disorder is seriously contaminated by false negative findings. Part II of this comprehensive review on antiepileptic drug (AED) inducers provides clinicians with further educational material about the complexity of interpreting AED drug-drug interactions. The basic pharmacology of induction is reviewed including the cytochrome P450 (CYP) isoenzymes, the Uridine Diphosphate Glucuronosyltransferases (UGTs), and P-glycoprotein (P-gp). CYP2B6 and CYP3A4 are very sensitive to induction. CYP1A2 is moderately sensitive while CYP2C9 and CYP2C19 are only mildly sensitive. CYP2D6 cannot be induced by medications. Induction of UGT and P-gp are poorly understood. The induction of metabolic enzymes such as CYPs and UGTs, and transporters such as P-gp, implies that the amount of these proteins increases when they are induced; this is almost always explained by increasing synthesis mediated by the so-called nuclear receptors (constitutive androstane, estrogen, glucocorticoid receptors and pregnaneX receptors). Although parti provides correction factors for AEDs, extrapolation from an average to an individual patient may be influenced by administration route, absence of metabolic enzyme for genetic reasons, and presence of inhibitors or other inducers. AED pharmacodynamic DDIs may also be important. Six patients with extreme sensitivity to AED inductive effects are described. Copyright © 2014 SEP y SEPB. Published by Elsevier España. All rights reserved.

Tangeretin inhibits the proliferation of human breast cancer cells via CYP1A1/CYP1B1 enzyme induction and CYP1A1/CYP1B1-mediated metabolism to the product 4' hydroxy tangeretin.

PubMed

Surichan, Somchaiya; Arroo, Randolph R; Tsatsakis, Aristidis M; Androutsopoulos, Vasilis P

2018-04-04

Tangeretin is a polymethoxylated flavone with multifaceted anticancer activity. In the present study, the metabolism of tangeretin was evaluated in the CYP1 expressing human breast cancer cell lines MCF7 and MDA-MB-468 and in the normal breast cell line MCF10A. Tangeretin was converted to 4' OH tangeretin by recombinant CYP1 enzymes and by CYP1 enzymes expressed in MCF7 and MDA-MB-468 cells. This metabolite was absent in MCF10A cells that did not express CYP1 enzymes. Tangeretin exhibited submicromolar IC50 (0.25 ± 0.15 μM) in MDA-MB-468 cells, whereas it was less active in MCF7 cells (39.3 ± 1.5 μM) and completely inactive in MCF10A cells (>100 μM). In MDA-MB-468 cells that were coincubated with the CYP1 inhibitor acacetin, an approximately 70-fold increase was noted in the IC50 (18 ± 1.6 μM) of tangeretin. In the presence of the CYP1 inhibitor acacetin, the conversion of tangeretin to 4' OH tangeretin was significantly reduced in MDA-MB-468 cells (2.55 ± 0.19 μM vs. 6.33 ± 0.12 μM). The mechanism of antiproliferative action involved cell cycle arrest at the G1 phase for MCF7 and MDA-MB-468 cells. Tangeretin was further shown to induce CYP1 enzyme activity and CYP1A1/CYP1B1 protein expression in MCF7 and MDA-MB-468 cells. These results suggest that tangeretin inhibits the proliferation of breast cancer cells via CYP1A1/CYP1B1-mediated metabolism to the product 4' hydroxy tangeretin. Copyright © 2018 Elsevier Ltd. All rights reserved.

Role of gemfibrozil as an inhibitor of CYP2C8 and membrane transporters.

PubMed

Tornio, Aleksi; Neuvonen, Pertti J; Niemi, Mikko; Backman, Janne T

2017-01-01

Cytochrome P450 (CYP) 2C8 is a drug metabolizing enzyme of major importance. The lipid-lowering drug gemfibrozil has been identified as a strong inhibitor of CYP2C8 in vivo. This effect is due to mechanism-based inhibition of CYP2C8 by gemfibrozil 1-O-β-glucuronide. In vivo, gemfibrozil is a fairly selective CYP2C8 inhibitor, which lacks significant inhibitory effect on other CYP enzymes. Gemfibrozil can, however, have a smaller but clinically meaningful inhibitory effect on membrane transporters, such as organic anion transporting polypeptide 1B1 and organic anion transporter 3. Areas covered: This review describes the inhibitory effects of gemfibrozil on CYP enzymes and membrane transporters. The clinical drug interactions caused by gemfibrozil and the different mechanisms contributing to the interactions are reviewed in detail. Expert opinion: Gemfibrozil is a useful probe inhibitor of CYP2C8 in vivo, but its effect on membrane transporters has to be taken into account in study design and interpretation. Moreover, gemfibrozil could be used to boost the pharmacokinetics of CYP2C8 substrate drugs. Identification of gemfibrozil 1-O-β-glucuronide as a potent mechanism-based inhibitor of CYP2C8 has led to recognition of glucuronide metabolites as perpetrators of drug-drug interactions. Recently, also acyl glucuronide metabolites of clopidogrel and deleobuvir have been shown to strongly inhibit CYP2C8.

Genetic polymorphisms in phase I and phase II enzymes and breast cancer risk associated with menopausal hormone therapy in postmenopausal women.

PubMed

2010-01-01

Recent findings indicate a greater risk of postmenopausal breast cancer with estrogen-progestagen therapy than estrogen monotherapy, and more so for current than past use. Few studies have examined individual genetic susceptibility to the effects of menopausal hormone therapy. We used two population-based case-control studies with 3,155 postmenopausal breast cancer patients and 5,496 controls to evaluate modification of breast cancer risk associated with duration of hormone use by genes involved in hormone metabolism and detoxification. Twenty-eight polymorphisms in eight genes of phase I (CYP1A1, CYP1A2, CYP1B1, CYP2C9, CYP2C19, CYP3A4, CYP3A5, CYP3A7) and nine genes of phase II enzymes (COMT, GSTM1, GSTM3, GSTP1, GSTT1, SULT1A1, UGT1A1, UGT1A6, UGT2B7) were genotyped. The risk associated with duration of use of combined estrogen-progestagen therapy was significantly modified by genetic polymorphisms located in CYP1B1, GSTP1, and GSTT1. In homozygote carriers of the CYP1B1_142_G and the CYP1B1_355 _T variant alleles, adjusted odds ratios (OR) per year of use were 1.06 (95% confidence interval (CI) = 1.02-1.09) and 1.06 (95% CI = 1.03-1.09), respectively, compared with 1.02 (95% CI = 1.01-1.03) in non-carriers of either polymorphism (p(interaction) = 0.01). Carriers of the functional GSTT1 allele and the GSTP1_341_T allele were at significantly higher risks associated with hormone use compared with non-carriers (p(interaction) = 0.0001 and 0.02). CYP1A1_2452_C>A significantly reduced the risk associated with duration of use of estrogen monotherapy (p(interaction) = 0.01). The finding regarding GSTT1 was still statistically significant after corrections for multiple comparisons. Postmenopausal breast cancer risk associated with hormone therapy may be modified by genetically determined variations in phase I and II enzymes involved in steroid hormone metabolism.

Metabolism of agrochemicals and related environmental chemicals based on cytochrome P450s in mammals and plants.

PubMed

Ohkawa, Hideo; Inui, Hideyuki

2015-06-01

A yeast gene expression system originally established for mammalian cytochrome P450 monooxygenase cDNAs was applied to functional analysis of a number of mammalian and plant P450 species, including 11 human P450 species (CYP1A1, CYP1A2, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C18, CYP2C19, CYP2D6, CYP2E1 and CYP3A4). The human P450 species CYP1A1, CYP1A2, CYP2B6, CYP2C18 and CYP2C19 were identified as P450 species metabolising various agrochemicals and environmental chemicals. CYP2C9 and CYP2E1 specifically metabolised sulfonylurea herbicides and halogenated hydrocarbons respectively. Plant P450 species metabolising phenylurea and sulfonylurea herbicides were also identified mainly as the CYP71 family, although CYP76B1, CYP81B1 and CYP81B2 metabolised phenylurea herbicides. The transgenic plants expressing these mammalian and plant P450 species were applied to herbicide tolerance as well as phytoremediation of agrochemical and environmental chemical residues. The combined use of CYP1A1, CYP2B6 and CYP2C19 belonging to two families and three subfamilies covered a wide variety of herbicide tolerance and phytoremediation of these residues. The use of 2,4-D-and bromoxynil-induced CYP71AH11 in tobacco seemed to enhance herbicide tolerance and selectivity. © 2014 Society of Chemical Industry.

Regulation of cytochrome P450 mRNA expression in primary porcine hepatocytes by selected secondary plant metabolites from chicory (Cichorium intybus L.).

PubMed

Rasmussen, Martin Krøyer; Klausen, Christina Lindgaard; Ekstrand, Bo

2014-03-01

Chicory (Cichorium intybus) has been shown to induce enzymes of pharmacokinetic relevance (cytochrome P450; CYP). The aim of this study was to investigate the effects of selected secondary plant metabolites with a global extract of chicory root, on the expression of hepatic CYP mRNA (1A2, 2A19, 2C33, 2D25, 2E1 and 3A29), using primary porcine hepatocytes. Of the tested secondary plant metabolites, artemisinin, scoparone, lactucin and esculetin all induced increased expression of specific CYPs, while esculin showed no effect. In contrast, a global extract of chicory root decreased the expression of CYP1A2, 2C33, 2D25 and 3A29 at high concentrations. The results suggest that purified secondary metabolites from chicory affect CYP expression and thereby might affect detoxification in general, and that global extracts of plants can have effects different from individual components. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of obesity on liver cytochromes P450 in various animal models.

PubMed

Tomankova, Veronika; Anzenbacher, Pavel; Anzenbacherova, Eva

2017-06-01

The prevalence of obesity and other obesity-related diseases is increasing worldwide. Obesity is a disease characterized by increased body weight, or a condition resulting from excessive accumulation of body fat. Due to increased body fat deposits, obesity has also been associated with increased mortality resulting from higher incidence rates of hypertension, diabetes, or various types of cancer, such as breast, colorectal, cervical and prostate cancer. Physiological changes associated with obesity are likely to result in altered drug biotransformation. The main enzymes enabling the oxidative biotransformation of most drugs are cytochromes P450 (CYPs). The review summarizes how pathophysiological factors, especially obesity, affect properties (e.g. enzyme activity, protein expression, gene expression) of CYP enzymes in various experimental models of human obesity. Results reported by various authors suggest that obesity is associated with a decrease of CYP activities (except for the CYP2C and CYP2E1 enzymes). The only exception is mouse obesity induced by monosodium glutamate (administered to newborn mice) as it usually leads to increased CYP expression. Selecting an animal model that is as close as possible to the properties of human obesity is of paramount importance.

CYP2C19 polymorphism frequency in Russian patients in Central Russia and Siberia with acute coronary syndrome

PubMed Central

Mirzaev, Karin B; Zelenskaya, Elena M; Barbarash, Olga L; Ganyukov, Vladimir I; Apartsin, Konstantin A; Saraeva, Natalya O; Nikolaev, Konstantin Y; Ryzhikova, Kristina A; Lifshits, Galina I; Sychev, Dmitry A

2017-01-01

Purpose The aim of this study is to investigate the frequency of CYP2C19*2, *3 allelic variants, associated with poor response to clopidogrel, and CYP2C19*17, associated with excessive response to clopidogrel, in patients with acute coronary syndrome (ACS) from Siberia and Moscow regions of Russia. Patients and methods The study included 512 ACS patients who were subsequently treated with coronary arterial stenting. The subjects assigned were from the cities of Central (Novosibirsk, Kemerovo), Eastern (Irkutsk), Northern (Surgut) Siberia regions and from Moscow region. The mean age of patients enrolled was 63.9±10.9 years. Among the assigned subjects, the proportion of men accounted for 80% and women 20%. Results According to the results obtained in the present study, from 16% up to 27.5% of patients in different regions of Russia have at least one CYP2C19 “poor metabolizer” (PM) allele variant affecting clopidogrel metabolism and, therefore, suppressing its antiplatelet activity. CYP2C19*17 allele variant was identified with the frequency of 15.4% up to 33.3%. The study revealed the presence of statistically significant differences in CYP2C19*3 allele frequency between the Russian ethnic group patients from Eastern and Central Siberia (p=0.001; odds ratio=1.05 [95% confidence interval 1.01–1.09]). Conclusion The study revealed statistically significant differences between the allele frequencies in Eastern and Central Siberia, which can probably be caused by a considerable number of Buryats inhabiting Eastern Siberia. PMID:28442925

Effective virtual screening protocol for CYP2C9 ligands using a screening site constructed from flurbiprofen and S-warfarin pockets

NASA Astrophysics Data System (ADS)

Polgár, Tímea; Menyhárd, Dóra K.; Keserű, György M.

2007-09-01

An effective virtual screening protocol was developed against an extended active site of CYP2C9, which was derived from X-ray structures complexed with flubiprofen and S-warfarin. Virtual screening has been effectively supported by our structure-based pharmacophore model. Importance of hot residues identified by mutation data and structural analysis was first estimated in an enrichment study. Key role of Arg108 and Phe114 in ligand binding was also underlined. Our screening protocol successfully identified 76% of known CYP2C9 ligands in the top 1% of the ranked database resulting 76-fold enrichment relative to random situation. Relevance of the protocol was further confirmed in selectivity studies, when 89% of CYP2C9 ligands were retrieved from a mixture of CYP2C9 and CYP2C8 ligands, while only 22% of CYP2C8 ligands were found applying the structure-based pharmacophore constraints. Moderate discrimination of CYP2C9 ligands from CYP2C18 and CYP2C19 ligands could also be achieved extending the application domain of our virtual screening protocol for the entire CYP2C family. Our findings further demonstrate the existence of an active site comprising of at least two binding pockets and strengthens the need of involvement of protein flexibility in virtual screening.

Design and synthesis of functionalized piperazin-1yl-(E)-stilbenes as inhibitors of 17α-hydroxylase-C17,20-lyase (Cyp17).

PubMed

Blass, Benjamin E; Iyer, Pravin; Abou-Gharbia, Magid; Childers, Wayne E; Gordon, John C; Ramanjulu, Mercy; Morton, George; Arumugam, Premkumar; Boruwa, Joshodeep; Ellingboe, John; Mitra, Sayan; Reddy Nimmareddy, Rajashekar; Paliwal, Shalini; Rajasekhar, Jamallamudi; Shivakumar, Savithiri; Srivastava, Pratima; Tangirala, Raghuram S; Venkataramanaiah, Konda; Bobbala, Ramreddy; Yanamandra, Mahesh; Krishnakanth Reddy, L

2018-07-15

The synthesis of steroid hormones is critical to human physiology and improper regulation of either the synthesis of these key molecules or activation of the associated receptors can lead to disease states. This has led to intense interest in developing compounds capable of modulating the synthesis of steroid hormones. Compounds capable of inhibiting Cyp19 (Aromatase), a key enzyme in the synthesis of estrogens, have been successfully employed as breast cancer therapies, while inhibitors of Cyp17 (17α-hydroxylase-17,20-lyase), a key enzyme in the synthesis of glucocorticoids, mineralocorticoids and steroidal sex hormones, are a key component of prostate cancer therapy. Inhibition of CYP17 has also been suggested as a possible target for the treatment of Cushing Syndrome and Metabolic Syndrome. We have identified two novel series of stilbene based CYP17 inhibitors and demonstrated that exemplary compounds in these series have pharmacokinetic properties consistent with orally delivered drugs. These findings suggest that compounds in these classes may be useful for the treatment of diseases and conditions associated with improper regulation of glucocorticoids synthesis and glucocorticoids receptor activation. Copyright © 2018. Published by Elsevier Ltd.

The basel cocktail for simultaneous phenotyping of human cytochrome P450 isoforms in plasma, saliva and dried blood spots.

PubMed

Donzelli, Massimiliano; Derungs, Adrian; Serratore, Maria-Giovanna; Noppen, Christoph; Nezic, Lana; Krähenbühl, Stephan; Haschke, Manuel

2014-03-01

Phenotyping cocktails use a combination of cytochrome P450 (CYP)-specific probe drugs to simultaneously assess the activity of different CYP isoforms. To improve the clinical applicability of CYP phenotyping, the main objectives of this study were to develop a new cocktail based on probe drugs that are widely used in clinical practice and to test whether alternative sampling methods such as collection of dried blood spots (DBS) or saliva could be used to simplify the sampling process. In a randomized crossover study, a new combination of commercially available probe drugs (the Basel cocktail) was tested for simultaneous phenotyping of CYP1A2, CYP2B6, CYP2C9, CYP2C19, CYP2D6 and CYP3A4. Sixteen subjects received low doses of caffeine, efavirenz, losartan, omeprazole, metoprolol and midazolam in different combinations. All subjects were genotyped, and full pharmacokinetic profiles of the probe drugs and their main metabolites were determined in plasma, dried blood spots and saliva samples. The Basel cocktail was well tolerated, and bioequivalence tests showed no evidence of mutual interactions between the probe drugs. In plasma, single timepoint metabolic ratios at 2 h (for CYP2C19 and CYP3A4) or at 8 h (for the other isoforms) after dosing showed high correlations with corresponding area under the concentration-time curve (AUC) ratios (AUC0-24h parent/AUC0-24h metabolite) and are proposed as simple phenotyping metrics. Metabolic ratios in dried blood spots (for CYP1A2 and CYP2C19) or in saliva samples (for CYP1A2) were comparable to plasma ratios and offer the option of minimally invasive or non-invasive phenotyping of these isoforms. This new combination of phenotyping probe drugs can be used without mutual interactions. The proposed sampling timepoints have the potential to facilitate clinical application of phenotyping but require further validation in conditions of altered CYP activity. The use of DBS or saliva samples seems feasible for phenotyping of the selected CYP isoforms.

Pharmacokinetic Drug Interactions with Tobacco, Cannabinoids and Smoking Cessation Products.

PubMed

Anderson, Gail D; Chan, Lingtak-Neander

2016-11-01

Tobacco smoke contains a large number of compounds in the form of metals, volatile gases and insoluble particles, as well as nicotine, a highly addictive alkaloid. Marijuana is the most widely used illicit drug of abuse in the world, with a significant increase in the USA due to the increasing number of states that allow medical and recreational use. Of the over 70 phytocannabinoids in marijuana, Δ 9 -tetrahydrocannabinol (Δ 9 THC), cannabidiol (CBD) and cannibinol are the three main constituents. Both marijuana and tobacco smoking induce cytochrome P450 (CYP) 1A2 through activation of the aromatic hydrocarbon receptor, and the induction effect between the two products is additive. Smoking cessation is associated with rapid downregulation of CYP1A enzymes. On the basis of the estimated half-life of CYP1A2, dose reduction of CYP1A drugs may be necessary as early as the first few days after smoking cessation to prevent toxicity, especially for drugs with a narrow therapeutic index. Nicotine is a substrate of CYP2A6, which is induced by oestrogen, resulting in lower concentrations of nicotine in females than in males, especially in females taking oral contraceptives. The significant effects of CYP3A4 inducers and inhibitors on the pharmacokinetics of Δ 9 THC/CBD oromucosal spray suggest that CYP3A4 is the primary enzyme responsible for the metabolism of Δ 9 THC and CBD. Limited data also suggest that CBD may significantly inhibit CYP2C19. With the increasing use of marijuana and cannabis products, clinical studies are needed in order to determine the effects of other drugs on pharmacokinetics and pharmacodynamics.

Insights into drug metabolism by cytochromes P450 from modelling studies of CYP2D6-drug interactions

PubMed Central

Maréchal, J-D; Kemp, C A; Roberts, G C K; Paine, M J I; Wolf, C R; Sutcliffe, M J

2008-01-01

The cytochromes P450 (CYPs) comprise a vast superfamily of enzymes found in virtually all life forms. In mammals, xenobiotic metabolizing CYPs provide crucial protection from the effects of exposure to a wide variety of chemicals, including environmental toxins and therapeutic drugs. Ideally, the information on the possible metabolism by CYPs required during drug development would be obtained from crystal structures of all the CYPs of interest. For some years only crystal structures of distantly related bacterial CYPs were available and homology modelling techniques were used to bridge the gap and produce structural models of human CYPs, and thereby obtain useful functional information. A significant step forward in the reliability of these models came seven years ago with the first crystal structure of a mammalian CYP, rabbit CYP2C5, followed by the structures of six human enzymes, CYP1A2, CYP2A6, CYP2C8, CYP2C9, CYP2D6 and CYP3A4, and a second rabbit enzyme, CYP2B4. In this review we describe as a case study the evolution of a CYP2D6 model, leading to the validation of the model as an in silico tool for predicting binding and metabolism. This work has led directly to the successful design of CYP2D6 mutants with novel activity—including creating a testosterone hydroxylase, converting quinidine from inhibitor to substrate, creating a diclofenac hydroxylase and creating a dextromethorphan O-demethylase. Our modelling-derived hypothesis-driven integrated interdisciplinary studies have given key insight into the molecular determinants of CYP2D6 and other important drug metabolizing enzymes. PMID:18026129

Potential of the novel antiretroviral drug rilpivirine to modulate the expression and function of drug transporters and drug-metabolising enzymes in vitro.

PubMed

Weiss, Johanna; Haefeli, Walter Emil

2013-05-01

The objective of this study was to assess the drug-drug interaction potential of the new non-nucleoside reverse transcriptase inhibitor (NNRTI) rilpivirine in vitro. The following were evaluated: P-glycoprotein (P-gp/ABCB1) inhibition by calcein assay; breast cancer resistance protein (BCRP/ABCG2) inhibition by pheophorbide A efflux; and inhibition of organic anion transporting polypeptide (OATP) 1B1 and OATP1B3 by 8-fluorescein-cAMP uptake. Inhibition of cytochrome P450 enzymes was assessed using commercially available kits. Substrate characteristics were evaluated by growth inhibition assays in MDCKII cells overexpressing particular ABC transporters. Induction of drug-metabolising enzymes and transporters was quantified by real-time RT-PCR in LS180 cells, and activation of pregnane X receptor (PXR) by a reporter gene assay. Rilpivirine significantly inhibited P-gp (IC(50) = 13.1 ± 6.8 μmol/L), BCRP (IC(50) = 1.5 ± 0.3 μmol/L), OATP1B1 (IC(50) = 4.1 ± 1.8 μmol/L), OATP1B3 (IC(50) = 6.1 ± 0.9 μmol/L), CYP3A4 (IC(50) = 1.3 ± 0.6 μmol/L), CYP2C19 (IC(50) = 2.7 ± 0.3 μmol/L) and CYP2B6 (IC(50) = 4.2 ± 1.6 μmol/L). Growth inhibition assays indicate that rilpivirine is not a substrate of P-gp, BCRP, or multidrug resistance-associated proteins 1 and 2. In LS180 cells, rilpivirine induced mRNA expression of ABCB1, CYP3A4 and UGT1A3, whereas ABCC1, ABCC2, ABCG2, OATP1B1 and UGT1A9 were not induced. Moreover, rilpivirine was a PXR activator. In conclusion, rilpivirine inhibits and induces several relevant drug-metabolising enzymes and drug transporters, but owing to its low plasma concentrations it is most likely less prone to drug-drug interactions than older NNRTIs. Copyright © 2013 Elsevier B.V. and the International Society of Chemotherapy. All rights reserved.

Bioengineering Anabolic Vitamin D-25-Hydroxylase Activity into the Human Vitamin D Catabolic Enzyme, Cytochrome P450 CYP24A1, by a V391L Mutation*

PubMed Central

Kaufmann, Martin; Prosser, David E.; Jones, Glenville

2011-01-01

CYP24A1 is a mitochondrial cytochrome P450 (CYP) that catabolizes 1α,25-dihydroxyvitamin D3 (1α,25-(OH)2D3) to different products: calcitroic acid or 1α,25-(OH)2D3-26,23-lactone via multistep pathways commencing with C24 and C23 hydroxylation, respectively. Despite the ability of CYP24A1 to catabolize a wide range of 25-hydroxylated analogs including 25-hydroxyvitamin D3, the enzyme is unable to metabolize the synthetic prodrug, 1α-hydroxyvitamin D3 (1α-OH-D3), presumably because it lacks a C25-hydroxyl. In the current study we show that a single V391L amino acid substitution in the β3a-strand of human CYP24A1 converts this enzyme from a catabolic 1α,25-(OH)2D3-24-hydroxylase into an anabolic 1α-OH-D3-25-hydroxylase, thereby forming the hormone, 1α,25-(OH)2D3. Furthermore, because the mutant enzyme retains its basal ability to catabolize 1α,25-(OH)2D3 via C24 hydroxylation, it can also make calcitroic acid. Previous work has shown that an A326G mutation is responsible for the regioselectivity differences observed between human (primarily C24-hydroxylating) and opossum (C23-hydroxylating) CYP24A1. When the V391L and A326G mutations were combined (V391L/A326G), the mutant enzyme continued to form 1α,25-(OH)2D3 from 1α-OH-D3, but this initial product was diverted via the C23 hydroxylation pathway into the 26,23-lactone. The relative position of Val-391 in the β3a-strand of a homology model and the crystal structure of rat CYP24A1 is consistent with hydrophobic contact of Val-391 and the substrate side chain near C21. We interpret that the substrate specificity of V391L-modified human CYP24A1 toward 1α-OH-D3 is enabled by an altered contact with the substrate side chain that optimally positions C25 of the 1α-OH-D3 above the heme for hydroxylation. PMID:21697097

Insights into molecular mechanisms of drug metabolism dysfunction of human CYP2C9*30

PubMed Central

Louet, Maxime; Labbé, Céline M.; Aono, Cassiano M.; Homem-de-Mello, Paula; Villoutreix, Bruno O.

2018-01-01

Cytochrome P450 2C9 (CYP2C9) metabolizes about 15% of clinically administrated drugs. The allelic variant CYP2C9*30 (A477T) is associated to diminished response to the antihypertensive effects of the prodrug losartan and affected metabolism of other drugs. Here, we investigated molecular mechanisms involved in the functional consequences of this amino-acid substitution. Molecular dynamics (MD) simulations performed for the active species of the enzyme (heme in the Compound I state), in the apo or substrate-bound state, and binding energy analyses gave insights into altered protein structure and dynamics involved in the defective drug metabolism of human CYP2C9.30. Our data revealed an increased rigidity of the key Substrate Recognition Sites SRS1 and SRS5 and shifting of the β turn 4 of SRS6 toward the helix F in CYP2C9.30. Channel and binding substrate dynamics analyses showed altered substrate channel access and active site accommodation. These conformational and dynamic changes are believed to be involved in the governing mechanism of the reduced catalytic activity. An ensemble of representative conformations of the WT and A477T mutant properly accommodating drug substrates were identified, those structures can be used for prediction of new CYP2C9 and CYP2C9.30 substrates and drug-drug interactions. PMID:29746595

In vitro inhibition of metabolism but not transport of gliclazide and repaglinide by Cree medicinal plant extracts.

PubMed

Cieniak, Carolina; Liu, Rui; Fottinger, Alexandra; Smiley, Sheila A M; Guerrero-Analco, Jose A; Bennett, Steffany A L; Haddad, Pierre S; Cuerrier, Alain; Saleem, Ammar; Arnason, John T; Foster, Brian C

2013-12-12

Interactions between conventional drug and traditional medicine therapies may potentially affect drug efficacy and increase the potential for adverse reactions. Cree traditional healing is holistic and patients may use medicinal plants simultaneously with the conventional drugs. However, there is limited information that these medicinal plants may interact with drugs and additional mechanistic information is required. In this study, extracts from traditionally used Cree botanicals were assessed for their potential interaction that could alter the disposition of two blood glucose lowering drugs, gliclazide (Diamicron) and repaglinide (Gluconorm) though inhibition of either metabolism or transport across cell membranes. The effect of 17 extracts on metabolism was examined in a human liver microsome assay by HPLC and individual cytochrome P450s 2C9, 2C19, 2C8 and 3A4 in a microplate fluorometric assay. Gliclazide, rhaponticin and its aglycone derivative, rhapontigenin were also examined in the fluorometric assay. The effect on transport was examined with 11 extracts using the intestinal epithelial Caco-2 differentiated cell monolayer model at times up to 180 min. Both blood glucose lowering medications, gliclazide and repaglinide traversed the Caco-2 monolayer in a time-dependent manner that was not affected by the Cree plant extracts. Incubation of the Cree plant extracts inhibited CYP2C9, 2C19, 2C8 and 3A4-mediated metabolism, and the formation of four repaglinide metabolites: M4, m/z 451-A, m/z 451-B and the glucuronide of repaglinide in the human liver microsome assay. Gliclazide caused no significant inhibition. Likewise, rhaponticin had little effect on the enzymes causing changes of less than 10% with an exception of 17% inhibition of CYP2C19. By contrast, the aglycone rhapontigenin showed the greatest effects on all CYP-mediated metabolism. Its inhibition ranged from a mean of 58% CYP3A4 inhibition to 89% inhibition of CYP2C9. While rhaponticin and the aglycone did not show significant effects on repaglinide metabolism, they demonstrated inhibition of gliclazide metabolism. The aglycone significantly affected levels of gliclazide and its metabolites. These studies demonstrate that the Cree plant extracts examined have the potential in vitro to cause drug interactions through effects on key metabolic enzymes. © 2013 Elsevier Ireland Ltd. All rights reserved.

Assessment of Pharmacokinetic Interactions Between Obeticholic Acid and Caffeine, Midazolam, Warfarin, Dextromethorphan, Omeprazole, Rosuvastatin, and Digoxin in Phase 1 Studies in Healthy Subjects.

PubMed

Edwards, Jeffrey E; Eliot, Lise; Parkinson, Andrew; Karan, Sharon; MacConell, Leigh

2017-09-01

Obeticholic acid (OCA), a potent and selective farnesoid X receptor agonist, is indicated for the treatment of primary biliary cholangitis (PBC). We investigated the potential drug-drug interaction effect of OCA on metabolic CYP450 enzymes and drug transporters. Five phase 1 single-center, open-label, fixed-sequence, inpatient studies were conducted in healthy adult subjects to evaluate the effect of oral daily doses of 10 or 25 mg OCA on single-dose plasma pharmacokinetics of specific probe substrates for enzymes CYP1A2 (caffeine, R-warfarin), CYP3A (midazolam, R-warfarin), CYP2C9 (S-warfarin), CYP2D6 (dextromethorphan), CYP2C19 (omeprazole), and drug transporters, BCRP/OATP1B1/OATP1B3 (rosuvastatin), and P-gp (digoxin). OCA showed no substantial suppression/inhibition of S-warfarin, digoxin, and dextromethorphan and weak interactions with caffeine, omeprazole, rosuvastatin, and midazolam. The maximal pharmacodynamic responses (E max ) to warfarin-based INR, PT, and aPTT were reduced by 11%, 11%, and 1%, respectively, for the 10-mg dose group and by 7%, 7% and 0%, respectively, for the 25-mg dose group. Overall, drugs dosed in combination with OCA were well tolerated, and most adverse events were mild in severity. No clinically important trends were noted in laboratory evaluations, vital signs, or 12-lead ECGs. In these studies, OCA showed weak to no suppression/inhibition of metabolic enzymes and drug transporters at the highest recommended therapeutic dose in patients with PBC. On the basis on these analyses, monitoring and maintenance of target INR range are required during coadministration of OCA with drugs that are metabolized by CYP1A2 (R-warfarin). Intercept Pharmaceuticals, Inc.

The Effects of Milk Thistle (Silybum marianum) on Human Cytochrome P450 Activity

PubMed Central

Kawaguchi-Suzuki, Marina; Frye, Reginald F.; Zhu, Hao-Jie; Brinda, Bryan J.; Chavin, Kenneth D.; Bernstein, Hilary J.

2014-01-01

Milk thistle (Silybum marianum) extracts are widely used as a complementary and alternative treatment of various hepatic conditions and a host of other diseases/disorders. The active constituents of milk thistle supplements are believed to be the flavonolignans contained within the extracts. In vitro studies have suggested that some milk thistle components may significantly inhibit specific cytochrome P450 (P450) enzymes. However, determining the potential for clinically significant drug interactions with milk thistle products has been complicated by inconsistencies between in vitro and in vivo study results. The aim of the present study was to determine the effect of a standardized milk thistle supplement on major P450 drug-metabolizing enzymes after a 14-day exposure period. CYP1A2, CYP2C9, CYP2D6, and CYP3A4/5 activities were measured by simultaneously administering the four probe drugs, caffeine, tolbutamide, dextromethorphan, and midazolam, to nine healthy volunteers before and after exposure to a standardized milk thistle extract given thrice daily for 14 days. The three most abundant falvonolignans found in plasma, following exposure to milk thistle extracts, were silybin A, silybin B, and isosilybin B. The concentrations of these three major constituents were individually measured in study subjects as potential perpetrators. The peak concentrations and areas under the time-concentration curves of the four probe drugs were determined with the milk thistle administration. Exposure to milk thistle extract produced no significant influence on CYP1A2, CYP2C9, CYP2D6, or CYP3A4/5 activities. PMID:25028567

Inhibition of aryl hydrocarbon receptor transactivation and DNA adduct formation by CYP1 isoform-selective metabolic deactivation of benzo[a]pyrene

DOE Office of Scientific and Technical Information (OSTI.GOV)

Endo, Kaori; Uno, Shigeyuki; Seki, Taiichiro

Benzo[a]pyrene (BaP), a polyaromatic hydrocarbon produced by the combustion of cigarettes and coke ovens, is a known procarcinogen. BaP activates the aryl hydrocarbon receptor (AhR) and induces the expression of a battery of genes, including CYP1A1, which metabolize BaP to toxic compounds. The possible role of CYP1 enzymes in mediating BaP detoxification or metabolic activation remains to be elucidated. In this study, we assessed the effects of CYP1 enzymes (CYP1A1, CYP1A2 and CYP1B1) on BaP-induced AhR transactivation and DNA adduct formation in HEK293 cells and HepG2 cells. Transfection of CYP1A1 and CYP1B1, but not CYP1A2, suppressed BaP-induced activation of AhR.more » Expression of CYP1A1 and CYP1A2, but not CYP1B1, inhibited DNA adduct formation in BaP-treated HepG2 cells. These results indicate that CYP1A1 and CYP1B1 play a role in deactivation of BaP on AhR and that CYP1A1 and CYP1A2 are involved in BaP detoxification by suppressing DNA adduct formation. BaP treatment did not induce DNA adduct formation in HEK293 cells, even after transfection of CYP1 enzymes, suggesting that expression of CYP1 enzymes is not sufficient for DNA adduct formation. Lower expression of epoxide hydrolase and higher expression of glutathione S-transferase P1 (GSTP1) and GSTM1/M2 were observed in HEK293 cells compared with HepG2 cells. Dynamic expression of CYP1A1, CYP1A2 and CYP1B1 along with expression of other enzymes such as epoxide hydrolase and phase II enzymes may determine the detoxification or metabolic activation of BaP.« less

In vivo pharmacokinetic interaction by ethanolic extract of Gymnema sylvestre with CYP2C9 (Tolbutamide), CYP3A4 (Amlodipine) and CYP1A2 (Phenacetin) in rats.

PubMed

Vaghela, Madhuri; Sahu, Niteshkumar; Kharkar, Prashant; Pandita, Nancy

2017-12-25

Gymnema sylvestre (GS) is a medicinal herb used for diabetes mellitus (DM). Herbs are gaining popularity as medicines in DM for its safety purpose. The aim of the present study was to evaluate in vivo pharmacokinetic (PK) interaction between allopathic drugs tolbutamide (TOLBU), amlodipine (AMLO), and phenacetin (PHENA) at low (L) and high (H) doses with ethanolic extract (EL) from GS. EL was extracted and subjected to TLC, total triterpenoid content (19.76 ± 0.02 W/W) and sterol content (0.1837 ± 0.0046 W/W) estimation followed by identification of phytoconstituents using HRLC-MS and GC-MS. PK interaction study with CYP2C9, CYP3A4 and CYP1A2 enzymes were assessed using TOLBU, AMLO and PHENA respectively to index cytochrome (CYP) mediated interaction in rats after concomitant administration of EL extract (400 mg/kg) from GS for 7 days. The rats were divided into four groups for each PK study where, group I and II were positive control for low and high dose of test drugs (CYP substrates) while group II and IV were orally administered EL. The PK study result of PHENA indicated that area under the plasma concentration-time curve (AUC 0-24 ) was significantly (P < 0.0001) increased by 1.4 (L) and 1.3-fold (H), plasma concentration (C max ) was significantly (P < 0.001) increased by 1.6 (L) and 1.4-fold (H). Whereas for TOLBU; clearance rate (CL) was significantly (P < 0.0001) decreased by 2.4 (L) and 2.3-fold (H), C max, was significantly (P < 0.001) decreased by 26.5% (L) and 50.4% (H) and AUC 0-24 was significantly (P < 0.0001) decreased by 59.8% (L) and 57.5% (H). Thus, EL is seen to be interacting with CYP1A2 by inhibiting its metabolic activity. HRLC-MS and GC-MS helped identify the presence of gymnemic acid (GA), triterpenoids and steroids in EL which could be the reason for PK interaction of CYP1A2 and CYP2C9. Also, in silico structure based site of metabolism study showed Fe accessibility and intrinsic activity for GA-IV, GA-VI, GA-VII and GA-X with CYP2C9. PK parameters of AMLO were not significantly affected by pre-treatment of EL. Thereby our findings indicate that co-administration of GS with drugs that are metabolized by CYP2C9 and CYP1A2 could lead to potential HDI. Copyright © 2017. Published by Elsevier B.V.

Human Cytochrome P450 Enzyme Modulation by Gymnema sylvestre: A Predictive Safety Evaluation by LC-MS/MS.

PubMed

Rammohan, Bera; Samit, Karmakar; Chinmoy, Das; Arup, Saha; Amit, Kundu; Ratul, Sarkar; Sanmoy, Karmakar; Dipan, Adhikari; Tuhinadri, Sen

2016-07-01

Traditionally GS is used to treat diabetes mellitus. Drug-herb interaction of GS via cytochrome P450 enzyme system by substrate cocktail method using HLM has not been reported. To evaluate the in-vitro modulatory effects of GS extracts (aqueous, methanol, ethyl acetate, chloroform and n -hexane) and deacylgymnemic acid (DGA) on human CYP1A2, 2C8, 2C9, 2D6 and 3A4 activities in HLM. Probe substrate-based LCMS/MS method was established for all CYPs. The metabolite formations were examined after incubation of probe substrates with HLM in the presence or absence of extracts and DGA. The inhibitory effects of GS extracts and DGA were characterized with kinetic parameters IC50 and Ki values. GS extracts showed differential effect on CYP activities in the following order of inhibitory potency: ethyl acetate > Chloroform > methanol > n -hexane > aqueous > DGA. This differential effect was observed against CYP1A2, 2C9 and less on CYP3A4 and 2C8 but all CYPs were unaffected by aqueous extract and DGA. The ethyl acetate and chloroform extract exhibited moderate inhibition towards CYP1A2 and 3A4. The aqueous extract and DGA however showed negligible inhibition towards all five major human CYPs with very high IC50 values (>90μg/ml). The results of our study revealed that phytoconstituents contained in GS, particularly in ethyl acetate and chloroform extracts, were able to inhibit CYP1A2, 3A4 and 2C9. The presence of relatively small, lipophillic yet slightly polar compounds within the GS extracts may be attributed for inhibition activities. These suggest that the herb or its extracts should be examined for potential pharmacokinetic drug interactions in vivo . Abbreviations used: GS: Gymnema sylvestre , GSE: Gymnema sylvestre extract, DGA: deacyl gymnemic acid, CYP: cytochrome P450, DMSO: dimethylsulphoxide, HLM: human liver microsomes, LC-MS/MS: liquid chromatography tandem mass spectroscopy, NADPH: reduced nicotinamide adeninedinucleotide phosphate, NRS: nicotinamide adeninedinucleotide phosphate regenerating system, CHE: chloroform extract, EAE: ethyl acetate extract, NHE- n -hexane extract, AE: aqueous extract, ME: methanol extract.

Distribution, metabolism and excretion of a synthetic androgen 7alpha-methyl-19-nortestosterone, a potential male-contraceptive.

PubMed

Prasad, Pramod Vishwanath; Arumugam, Ramamani; Willman, Mark; Ge, Ren-Shan; Sitruk-Ware, Regine; Kumar, Narender

2009-01-01

A synthetic androgen 7alpha-Methyl-19-nortestosterone (MENT) has a potential for therapeutic use in 'androgen replacement therapy' for hypogonadal men or as a hormonal male-contraceptive in normal men. Its tissue distribution, excretion and metabolic enzyme(s) have not been reported. Therefore, the present study tested the distribution and excretion of MENT in Sprague-Dawley rats castrated 24h prior to the injection of tritium-labeled MENT ((3)H-MENT). Rats were euthanized at different time intervals after dosing, and the amount of radioactivity in various tissues/organs was measured following combustion in a Packard oxidizer. The radioactivity (% injected dose) was highest in the duodenal contents in the first 30min of injection. Specific uptake of the steroid was observed in target tissues such as ventral prostate and seminal vesicles at 6h, while in other tissues radioactivity equilibrated with blood. Liver and duodenum maintained high radioactivity throughout, as these organs were actively involved in the metabolism and excretion of most drugs. The excretion of (3)H-MENT was investigated after subcutaneous injection of (3)H-MENT into male rats housed in metabolic cages. Urine and feces were collected at different time intervals (up to 72h) following injection. Results showed that the radioactivity was excreted via feces and urine in equal amounts by 30h. Aiming to identify enzyme(s) involved in the MENT metabolism, we performed in vitro metabolism of (3)H-MENT using rat and human liver microsomes, cytosol and recombinant cytochrome P(450) (CYP) isozymes. The metabolites were separated by thin-layer chromatography (TLC). Three putative metabolites (in accordance with the report of Agarwal and Monder [Agarwal AK, Monder C. In vitro metabolism of 7alpha-methyl-19-nortestosterone by rat liver, prostate, and epididymis. Endocrinology 1988;123:2187-93]), [i] 3-hydroxylated MENT by both rat and human liver cytosol; [ii] 16alpha-hydroxylated MENT (a polar metabolite) by both rat and human hepatic microsomes; and [iii] 7alpha-methyl-19-norandrostenedione (a non-polar metabolite) by human hepatic microsomes, were obtained. By employing chemical inhibitors and specific anti-CYP antibodies, (3)H-MENT was found to be metabolized specifically by rat CYP 2C11 and 3-hydroxysteroid dehydrogenase (3-HSD) enzymes whereas in humans it was accomplished by CYP 3A4, 17beta-hydroxysteroid dehydrogenase (17beta-HSD) and 3-HSD enzymes.

Pharmacokinetic Effects of Isavuconazole Coadministration With the Cytochrome P450 Enzyme Substrates Bupropion, Repaglinide, Caffeine, Dextromethorphan, and Methadone in Healthy Subjects

PubMed Central

Yamazaki, Takao; Desai, Amit; Goldwater, Ronald; Han, David; Howieson, Corrie; Akhtar, Shahzad; Kowalski, Donna; Lademacher, Christopher; Pearlman, Helene; Rammelsberg, Diane

2016-01-01

Abstract This report describes phase 1 clinical trials performed to assess interactions of oral isavuconazole at the clinically targeted dose (200 mg, administered as isavuconazonium sulfate 372 mg, 3 times a day for 2 days; 200 mg once daily [QD] thereafter) with single oral doses of the cytochrome P450 (CYP) substrates: bupropion hydrochloride (CYP2B6; 100 mg; n = 24), repaglinide (CYP2C8/CYP3A4; 0.5 mg; n = 24), caffeine (CYP1A2; 200 mg; n = 24), dextromethorphan hydrobromide (CYP2D6/CYP3A4; 30 mg; n = 24), and methadone (CYP2B6/CYP2C19/CYP3A4; 10 mg; n = 23). Compared with each drug alone, coadministration with isavuconazole changed the area under the concentration‐time curves (AUC∞) and maximum concentrations (Cmax) as follows: bupropion, AUC∞ reduced 42%, Cmax reduced 31%; repaglinide, AUC∞ reduced 8%, Cmax reduced 14%; caffeine, AUC∞ increased 4%, Cmax reduced 1%; dextromethorphan, AUC∞ increased 18%, Cmax increased 17%; R‐methadone, AUC∞ reduced 10%, Cmax increased 3%; S‐methadone, AUC∞ reduced 35%, Cmax increased 1%. In all studies, there were no deaths, 1 serious adverse event (dextromethorphan study; perioral numbness, numbness of right arm and leg), and adverse events leading to study discontinuation were rare. Thus, isavuconazole is a mild inducer of CYP2B6 but does not appear to affect CYP1A2‐, CYP2C8‐, or CYP2D6‐mediated metabolism. PMID:27273149

Increased carrier prevalence of deficient CYP2C9, CYP2C19 and CYP2D6 alleles in depressed patients referred to a tertiary psychiatric hospital.

PubMed

Ruaño, Gualberto; Villagra, David; Rahim, Umme Salma; Windemuth, Andreas; Kocherla, Mohan; Bower, Bruce; Szarek, Bonnie L; Goethe, John W

2008-11-01

This study compared the types and carrier prevalences of clinically significant DNA polymorphisms in the cytochrome P450 (CYP450) genes CYP2C9, CYP2C19 and CYP2D6 in major depressive disorder patients with a control group of nonpsychiatrically ill, medical outpatients. We conducted a case-control study using 73 psychiatric outpatients diagnosed with depression and referred to a tertiary center, The Institute of Living (Hartford, CT, USA), for treatment resistance or intolerable side-effects to psychotropic drugs. The controls were 120 cardiovascular patients from Hartford Hospital being treated for dyslipidemia but otherwise healthy and not psychiatrically ill. DNA typing to detect polymorphisms in the genes CYP2C9, CYP2C19 and CYP2D6 was accomplished with the Tag-It™ mutation detection assay and the Luminex xMAP ® system. The percentage of individuals in psychiatric versus control groups with two wild-type alleles for CYP2C9, CYP2C19 and CYP2D6 genes, were 50 versus 74% (p < 0.001), 71 versus 73% (not statistically significant) and 36 versus 43% (trend, p < 0.2), respectively. Within the psychiatric population, 57% of individuals were carriers of non-wild-type alleles for 2-3 genes, compared with 36% in the control population (p < 0.0001). The balance, 43% in the psychiatric population and 64% in the control, were carriers of non-wild-type alleles for none or one gene. These findings reveal that clinically relevant CYP2C9 polymorphisms occur more frequently in depressed psychiatric patients than in nonpsychiatric controls. The same trend was found for polymorphisms in the CYP2D6 gene. We found a significant cumulative metabolic deficiency in the psychiatric population for combinations of the CYP2C9, CYP2C19 and CYP2D6 genes. The significant enrichment of CYP2C9-deficient alleles in the psychiatric population validates a previously reported association of this gene with the risk for depression disorders. The high prevalence of carriers with deficient and null alleles suggests that CYP450 DNA typing may play a role in the management of psychiatric patients at tertiary care institutions.

Inhibition of cytochrome P450 enzymes by saturated and unsaturated fatty acids in human liver microsomes, characterization of enzyme kinetics in the presence of bovine serum albumin (0.1 and 1.0% w/v) and in vitro - in vivo extrapolation of hepatic clearance.

PubMed

Palacharla, Raghava Choudary; Uthukam, Venkatesham; Manoharan, Arunkumar; Ponnamaneni, Ranjith Kumar; Padala, Nagasurya Prakash; Boggavarapu, Rajesh Kumar; Bhyrapuneni, Gopinadh; Ajjala, Devender Reddy; Nirogi, Ramakrishna

2017-04-01

The objective of the study was to determine the effect of fatty acids on CYP enzymes and the effect of BSA on intrinsic clearance of probe substrates. The inhibitory effect of thirteen fatty acids including saturated, mono-unsaturated and polyunsaturated fatty acids on CYP enzymes, kinetic parameters and intrinsic clearance values of nine CYP marker probe substrate reactions in the absence and presence of BSA (0.1 and 1.0% w/v) were characterized in human liver microsomes. The results demonstrate that most of the unsaturated fatty acids showed marked inhibition towards CYP2C8 mediated amodiaquine N-deethylation followed by inhibition of CYP2C9 and CYP2B6 mediated activities. The addition of 0.1% BSA in the incubation markedly improved the unbound intrinsic clearance values of probe substrates by reducing the K m values with little or no effect on maximal velocity. The addition of BSA (0.1 and 1.0% w/v) did not influence the unbound intrinsic clearance of marker reactions for CYP2A6, and CYP3A4 enzymes. The addition of 0.1% w/v BSA is sufficient to determine the intrinsic clearance of marker probe reactions by metabolite formation approach. The predicted hepatic clearance values for the substrates using the well-stirred model, in the presence of BSA (0.1% BSA), are comparable to the in vivo hepatic clearance values. Copyright © 2017 Elsevier B.V. All rights reserved.

Human variation in CYP-specific chlorpyrifos metabolism.

PubMed

Croom, Edward L; Wallace, Andrew D; Hodgson, Ernest

2010-10-29

Chlorpyrifos, an organophophorothioate insecticide, is bioactivated to the neurotoxic metabolite, chlorpyrifos-oxon (CPO) by cytochromes P450 (CYPs). To determine the variability in chlorpyrifos bioactivation, CPO production by human liver microsomes from 17 individual donors was compared relative to phenotype and genotype. CPO production varied over 14-fold between individuals in incubations utilizing 20 μM chlorpyrifos as substrate, while CPO production varied 57-fold in incubations with 100 μM chlorpyrifos. For all but two samples, the formation of the less toxic metabolite, 3,5,6-trichloro-2-pyridinol (TCP), was greater than CPO production. TCP production varied 9-fold in incubations utilizing 20 μM chlorpyrifos as substrate and 19-fold using 100 μM chlorpyrifos. Chlorpyrifos metabolism by individual human liver microsomes was significantly correlated with CYP2B6, CYP2C19 and CYP3A4 related activity. CPO formation was best correlated with CYP2B6 related activity at low (20 μM) chlorpyrifos concentrations while CYP3A4 related activity was best correlated with CPO formation at high concentrations (100 μM) of chlorpyrifos. TCP production was best correlated with CYP3A4 activity at all substrate concentrations of chlorpyrifos. The production of both CPO and TCP was significantly lower at a concentration of 20 μM chlorpyrifos as compared to 100 μM chlorpyrifos. Calculations of percent total normalized rates (% TNR) and the chemical inhibitors ketoconazole and ticlopidine were used to confirm the importance of CYP2B6, CYP2C19, and CYP3A4 for the metabolism of chlorpyrifos. The combination of ketoconazole and ticlopidine inhibited the majority of TCP and CPO formation. CPO formation did not differ by CYP2B6 genotype. Individual variations in CPO production may need to be considered in determining the risk of chlorpyrifos poisoning. Copyright © 2010 Elsevier Ireland Ltd. All rights reserved.

Caffeine based measures of CYP1A2 activity correlate with oral clearance of tacrine in patients with Alzheimer's disease

PubMed Central

Fontana, Robert J; deVries, Tina M; Woolf, Thomas F; Knapp, Margaret J; Brown, AS; Kaminsky, Laurence S; Tang, Bing-Kuo; Foster, Norman L; Brown, Richard R; Watkins, Paul B

1998-01-01

Aims To study the potential utility of caffeine based probes of CYP1A2 enzyme activity in predicting the pharmokinetics of tacrine in patients with Alzheimer's disease. Methods The pharmokinetics of a single 40 mg oral dose of tacrine were measured in 19 patients with Alzheimer's disease. Each patient also received 2 mg kg−1 [13C-3-methyl] caffeine orally and had breath and urine samples collected. Results Tacrine oral clearance (CL F−1 kg−1 ), which varied 15-fold among the patients, correlated significantly with the 2 h total production of 13CO2 in breath (r=0.56, P=0.01), and with each of two commonly used urinary caffeine metabolite ratios: the raxanthine/caffeine ratio’ (1,7X+1, 7U)/1,3,7X) (r=0.76, P=0.0002) and the ‘caffeine metabolic ratio’ (AFMU+1X+1U)/1, 7U)(r=0.76, P=0.0001). Conclusions These observations support a central role for CYP1A2 in the in vivo disposition of tacrine and the potential for drug interactions when tacrine treated patients receive known inducers or inhibitors of this enzyme. The magnitude of the correlations we observed, however, are probably not suffcient to be clinically useful in individualizing tacrine therapy. PMID:9764962

The Use of Immobilized Cytochrome P4502C9 in PMMA-Based Plug-Flow Bioreactors for the Production of Drug Metabolites

PubMed Central

Wollenberg, Lance A.; Kabulski, Jarod L.; Powell, Matthew J.; Chen, Jifeng; Flora, Darcy R.; Tracy, Timothy S.; Gannett, Peter M.

2013-01-01

Cytochrome P450 enzymes play a key role in the metabolism of pharmaceutical agents. To determine metabolite toxicity, it is necessary to obtain P450 metabolites from various pharmaceutical agents. Here, we describe a bioreactor that is made by immobilizing cytochrome P450 2C9 (CYP2C9) to a poly (methyl methacrylate) surface and, as an alternative to traditional chemical synthesis, can be used to biosynthesize P450 metabolites in a plug-flow bioreactor. As part of the development of the CYP2C9 bioreactor, we have studied two different methods of attachment: 1) coupling via the N-terminus using N-hydroxysulfosuccinimide 1-ethyl-3-(3-dimethylaminopropyl)-carbodiimide and 2) using the Ni(II) chelator 1-acetato-4-benzyl-triazacyclononane to coordinate the enzyme to the surface using a C-terminal histidine tag. Additionally, the propensity for metabolite production of the CYP2C9 proof-of-concept bioreactors as a function of enzyme attachment conditions (e.g., time and enzyme concentration) was examined. Our results show that the immobilization of CYP2C9 enzymes to a PMMA surface represents a viable and alternative approach to the preparation of CYP2C9 metabolites for toxicity testing. Furthermore, the basic approach can be adapted to any cytochrome P450 enzyme and in a high-throughput, automated process. PMID:24166101

Effects of Cytochrome P450 (CYP) 2C19 Genotypes on Steady-State Plasma Concentrations of Escitalopram and its Desmethyl Metabolite in Japanese Patients With Depression.

PubMed

Tsuchimine, Shoko; Ochi, Shinichiro; Tajiri, Misuzu; Suzuki, Yutaro; Sugawara, Norio; Inoue, Yoshimasa; Yasui-Furukori, Norio

2018-06-01

Plasma concentrations of the S-enantiomer of citalopram were different between extensive and poor CYP2C19 metabolizers in healthy subjects and depressed patients. However, most studies applied dose-corrected concentrations. Thus, we studied the effects of polymorphisms of the CYP2C19 gene on raw plasma drug concentrations in Japanese patients with depression. Subjects in this study consisted of 412 depressed patients receiving 5, 10, 15, or 20 mg of escitalopram once a day. Plasma concentrations of escitalopram and desmethylescitalopram were quantified using HPLC. CYP2C19 genotypes were identified using polymerase chain reaction methods. There were no differences in the steady-state plasma concentrations of escitalopram or desmethylescitalopram in each dose group (5, 10, 15, or 20 mg of escitalopram) among CYP2C19 genotype groups. However, 1-way analysis of variance showed significant effects of CYP2C19 genotypes on the dose-adjusted plasma concentration of escitalopram but not in the dose-adjusted plasma concentration of desmethylescitalopram. Analysis of covariance including age, sex, and body weight showed significant effects of CYP2C19 genotypes on the dose-adjusted plasma concentration of escitalopram and the ratio of desmethylescitalopram to escitalopram. These findings suggest that the CYP2C19 variants are associated with steady-state plasma concentrations of escitalopram to some extent but are not associated with desmethylescitalopram.

Studies on the interactions between drugs and estrogen: analytical method for prediction system of gynecomastia induced by drugs on the inhibitory metabolism of estradiol using Escherichia coli coexpressing human CYP3A4 with human NADPH-cytochrome P450 reductase.

PubMed

Satoh, T; Fujita, K I; Munakata, H; Itoh, S; Nakamura, K; Kamataki, T; Itoh, S; Yoshizawa, I

2000-11-15

To establish a prediction system for drug-induced gynecomastia in clinical fields, a model reaction system was developed to explain numerically this side effect. The principle is based on the assumption that 50% inhibition concentration (IC(50)) of drugs on the in vitro metabolism of estradiol (E2) to its major product 2-hydroxyestradiol (2-OH-E2) can be regarded as the index for achieving this purpose. By using human cytochrome P450s coexpressed with human NADPH-cytochrome P450 reductase in Escherichia coli as the enzyme, the reaction was examined. Among the nine enzymes (CYP1A1, 1A2, 2A6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4) tested, CYP3A4 having a V(max)/K(m) (ml/min/nmol P450) value of 0.32 for production of 2-OH-E2 was shown to be the most suitable enzyme as the reagent. The inhibitory effects of ketoconazole, cyclosporin A, and cimetidine toward the 2-hydroxylation of E2 catalyzed by CYP3A4 were obtained, and their IC(50) values were 7 nM, 64 nM, and 290 microM, respectively. The present results suggest that IC(50) values thus obtained can be substituted as the prediction index for gynecomastia induced by drugs, considering the patients' individual information. Copyright 2000 Academic Press.

Influence of CYP2C19 polymorphism on the pharmacokinetics of nelfinavir and its active metabolite

PubMed Central

Damle, Bharat D; Uderman, Howard; Biswas, Pinaki; Crownover, Penelope; Lin, Chang; Glue, Paul

2009-01-01

AIMS This study reports the pharmacokinetics of nelfinavir, its active metabolite, M8, and active moiety (nelfinavir + M8) in volunteers genotyped for CYP2C19 as extensive metabolizer (*1*1; n = 38), heterozygous poor metabolizer (PM) (*1*2; n = 22) and homozygous PM (*2*2; n = 6). METHODS Subjects received nelfinavir at normal dose (3.5 days of 1250 mg q12h) or high dose (1250 mg q12h for 3 days and single dose of 3125 mg on day 4). Steady-state plasma samples were analysed by high-performance liquid chromatography/ultraviolet assay to determine pharmacokinetics. RESULTS At steady state, the mean Cmax was 42% [95% confidence interval (CI) 19, 69] and 63% (95% CI 20, 122) higher, and mean AUC was 51% (95% CI 24, 83) and 85% (95% CI 32, 159) higher for *1*2 and *2*2 compared with *1*1 subjects, respectively. For M8, the mean Cmax and AUC were 35% (95% CI 6, 55) and 33% (95% CI −3, 56), respectively, lower for *1*2 compared with *1*1 subjects. M8 was not detectable in *2*2 subjects. The mean Cmax and AUC values for the active moiety were higher by 30–35% for the *1*2 and *2*2 compared with *1*1 subjects. CONCLUSIONS Mutation in CYP2C19 increased the systemic exposure of nelfinavir and reduced the exposure of M8. No significant differences were noted among the heterozygous (*1*2) and homozygous (*2*2) PMs. These changes are not considered to be clinically relevant and hence the use of nelfinavir does not require prior assessment of CYP2C19 genotype. PMID:19916992

CYP2C19 genetic polymorphism, rabeprazole and esomeprazole have no effect on the antiplatelet action of clopidogrel.

PubMed

El-Halabi, Mustapha M; Zgheib, Nathalie; Mansour, Nabil M; Malli, Ahmad; Ghaith, Ola A; Mahfouz, Rami; Alam, Samir; Sharara, Ala I

2013-07-01

The aim of this study is to investigate the effect of CYP2C19 polymorphism and cotherapy with rabeprazole or esomeprazole on the antiplatelet effect of clopidogrel. Patients receiving clopidogrel 75 mg ± rabeprazole or esomeprazole underwent genotyping for CYP2C19*2 and CYP2C19*3, and vasodilator-stimulated phosphoprotein testing to measure platelet reactivity index (PRI). Two hundred thirty-nine consecutive patients were enrolled as follows: 92 clopidogrel (C group), 94 clopidogrel + rabeprazole (CR), and 53 clopidogrel + esomeprazole (CE). Forty-five patients had loss of function (LOF) polymorphism (43 heterozygous; 2 homozygous mutant for CYP2C19*2). The mean PRI was 20.7% ± 21.9% in the C group, 19.1% ± 20.9% in the CR group, and 24.5% ± 22.9% in the CE group (P = NS). High on-treatment platelet reactivity (HPR), defined as PRI >50%, was observed in 12 (13.0%), 13 (13.8%), and 10 (18.9%) patients on C, CR, and CE, respectively (P = NS). HPR was similar in rapid metabolizers between groups. On multivariate logistic regression, neither CYP2C19 LOF alleles nor proton pump inhibitor cotherapy were associated with HPR. The use of proton pump inhibitors was indicated in 30.6% of recipients. As a conclusion, CYP2C19*2 LOF allele and the use of esomeprazole or rabeprazole have no effect on the action of clopidogrel.

Flavonoids exhibit diverse effects on CYP11B1 expression and cortisol synthesis

DOE Office of Scientific and Technical Information (OSTI.GOV)

Cheng, Li-Chuan; Li, Lih-Ann, E-mail: lihann@nhri.org.tw

2012-02-01

CYP11B1 catalyzes the final step of cortisol biosynthesis. The effects of flavonoids on transcriptional expression and enzyme activity of CYP11B1 were investigated using the human adrenocortical H295R cell model. All tested nonhydroxylated flavones including 3′,4′-dimethoxyflavone, α-naphthoflavone, and β-naphthoflavone upregulated CYP11B1 expression and cortisol production, whereas apigenin and quercetin exhibited potent cytotoxicity and CYP11B1 repression at high concentrations. Nonhydroxylated flavones stimulated CYP11B1-catalyzed cortisol formation at transcriptional level. Resveratrol increased endogenous and substrate-supported cortisol production like nonhydroxylated flavones tested, but it had no effect on CYP11B1 gene expression and enzyme activity. Resveratrol appeared to alter cortisol biosynthesis at an earlier step. Themore » Ad5 element situated in the − 121/− 106 region was required for basal and flavone-induced CYP11B1 expression. Overexpression of COUP-TFI did not improve the responsiveness of Ad5 to nonhydroxylated flavones. Although COUP-TFI overexpression increased CYP11B1 and CYP11B2 promoter activation, its effect was not mediated through the common Ad5 element. Treating cells with PD98059 (a flavone-type MEK1 inhibitor) increased CYP11B1 promoter activity, but not involving ERK signaling because phosphorylation of ERK1/2 remained unvarying throughout the course of treatment. Likewise, AhR was not responsible for the CYP11B1-modulating effects of flavonoids because inconsistency with their effects on AhR activation. 3′,4′-dimethoxyflavone and 8-Br-cAMP additively activated CYP11B1 promoter activity. H-89 reduced 3′,4′-dimethoxyflavone-induced CYP11B1 promoter activation but to a lesser extent as compared to its inhibition on cAMP-induced transactivation. Our data suggest that constant exposure to nonhydroxylated flavones raises a potential risk of high basal and cAMP-induced cortisol synthesis in consequence of increased CYP11B1 expression. -- Highlights: ► Nonhydroxylated flavones stimulate basal cortisol synthesis and CYP11B1 expression. ► The Ad5 element is required for nonhydroxylated flavone-elicited CYP11B1 induction. ► COUP-TFI elevates CYP11B1 and CYP11B2 transactivation but not through Ad5. ► AhR, ERK, and PKA are not involved in nonhydroxylated flavone-mediated regulation. ► Resveratrol affects cortisol biosynthesis at a step earlier than CYP11B1.« less

Frequency distribution of polymorphisms of CYP2C19, CYP2C9, VKORC1 and SLCO1B1 genes in the Yakut population.

PubMed

Vasilyev, Filipp Filippovich; Danilova, Diana Aleksandrovna; Kaimonov, Vladimir Sergeevich; Chertovskih, Yana Valerievna; Maksimova, Nadezda Romanovna

2016-01-01

Allele frequencies of single nucleotide polymorphisms (SNPs) are variable among different populations; therefore the study of SNPs in ethnic groups is important for establishing the clinical significance of the screening of these polymorphisms. The main goal of the research is to study the polymorphisms of CYP2C9, CYP2C19, VKORC1, and SLCO1B1 in Yakuts. Genomic DNA from 229 Yakut subjects were analyzed by real-time polymerase chain reaction (PCR) (SLCO1B1 +521T > C, VKORC1 -1639G>A, CYP2C19 +681G>A, +636G>A, CYP2C9 +430С>T, +1075A>C). Genotype frequencies of polymorphisms in the population of the Yakuts were more characteristic of the Asian population. The results have been included in the software application "Lekgen" that we developed for the interpretation of pharmacogenetic testing. The data of our study obtained on frequency carriers of polymorphisms of genes SLCO1B1, CYP2C19, CYP2C9, VKORC1 among the Yakuts may be useful in developing recommendations for a personalized therapy.

Frequency distribution of polymorphisms of CYP2C19, CYP2C9, VKORC1 and SLCO1B1 genes in the Yakut population

PubMed Central

Vasilyev, Filipp Filippovich; Danilova, Diana Aleksandrovna; Kaimonov, Vladimir Sergeevich; Chertovskih, Yana Valerievna; Maksimova, Nadezda Romanovna

2016-01-01

Allele frequencies of single nucleotide polymorphisms (SNPs) are variable among different populations; therefore the study of SNPs in ethnic groups is important for establishing the clinical significance of the screening of these polymorphisms. The main goal of the research is to study the polymorphisms of CYP2C9, CYP2C19, VKORC1, and SLCO1B1 in Yakuts. Genomic DNA from 229 Yakut subjects were analyzed by real-time polymerase chain reaction (PCR) (SLCO1B1 +521T > C, VKORC1 -1639G>A, CYP2C19 +681G>A, +636G>A, CYP2C9 +430С>T, +1075A>C). Genotype frequencies of polymorphisms in the population of the Yakuts were more characteristic of the Asian population. The results have been included in the software application “Lekgen” that we developed for the interpretation of pharmacogenetic testing. The data of our study obtained on frequency carriers of polymorphisms of genes SLCO1B1, CYP2C19, CYP2C9, VKORC1 among the Yakuts may be useful in developing recommendations for a personalized therapy. PMID:27499796

Cytochrome P450 associated with insecticide resistance catalyzes cuticular hydrocarbon production in Anopheles gambiae.

PubMed

Balabanidou, Vasileia; Kampouraki, Anastasia; MacLean, Marina; Blomquist, Gary J; Tittiger, Claus; Juárez, M Patricia; Mijailovsky, Sergio J; Chalepakis, George; Anthousi, Amalia; Lynd, Amy; Antoine, Sanou; Hemingway, Janet; Ranson, Hilary; Lycett, Gareth J; Vontas, John

2016-08-16

The role of cuticle changes in insecticide resistance in the major malaria vector Anopheles gambiae was assessed. The rate of internalization of (14)C deltamethrin was significantly slower in a resistant strain than in a susceptible strain. Topical application of an acetone insecticide formulation to circumvent lipid-based uptake barriers decreased the resistance ratio by ∼50%. Cuticle analysis by electron microscopy and characterization of lipid extracts indicated that resistant mosquitoes had a thicker epicuticular layer and a significant increase in cuticular hydrocarbon (CHC) content (∼29%). However, the CHC profile and relative distribution were similar in resistant and susceptible insects. The cellular localization and in vitro activity of two P450 enzymes, CYP4G16 and CYP4G17, whose genes are frequently overexpressed in resistant Anopheles mosquitoes, were analyzed. These enzymes are potential orthologs of the CYP4G1/2 enzymes that catalyze the final step of CHC biosynthesis in Drosophila and Musca domestica, respectively. Immunostaining indicated that both CYP4G16 and CYP4G17 are highly abundant in oenocytes, the insect cell type thought to secrete hydrocarbons. However, an intriguing difference was indicated; CYP4G17 occurs throughout the cell, as expected for a microsomal P450, but CYP4G16 localizes to the periphery of the cell and lies on the cytoplasmic side of the cell membrane, a unique position for a P450 enzyme. CYP4G16 and CYP4G17 were functionally expressed in insect cells. CYP4G16 produced hydrocarbons from a C18 aldehyde substrate and thus has bona fide decarbonylase activity similar to that of dmCYP4G1/2. The data support the hypothesis that the coevolution of multiple mechanisms, including cuticular barriers, has occurred in highly pyrethroid-resistant An gambiae.

Cytochrome P450 associated with insecticide resistance catalyzes cuticular hydrocarbon production in Anopheles gambiae

PubMed Central

Balabanidou, Vasileia; Kampouraki, Anastasia; MacLean, Marina; Blomquist, Gary J.; Tittiger, Claus; Juárez, M. Patricia; Mijailovsky, Sergio J.; Chalepakis, George; Anthousi, Amalia; Lynd, Amy; Antoine, Sanou; Hemingway, Janet; Ranson, Hilary; Lycett, Gareth J.; Vontas, John

2016-01-01

The role of cuticle changes in insecticide resistance in the major malaria vector Anopheles gambiae was assessed. The rate of internalization of 14C deltamethrin was significantly slower in a resistant strain than in a susceptible strain. Topical application of an acetone insecticide formulation to circumvent lipid-based uptake barriers decreased the resistance ratio by ∼50%. Cuticle analysis by electron microscopy and characterization of lipid extracts indicated that resistant mosquitoes had a thicker epicuticular layer and a significant increase in cuticular hydrocarbon (CHC) content (∼29%). However, the CHC profile and relative distribution were similar in resistant and susceptible insects. The cellular localization and in vitro activity of two P450 enzymes, CYP4G16 and CYP4G17, whose genes are frequently overexpressed in resistant Anopheles mosquitoes, were analyzed. These enzymes are potential orthologs of the CYP4G1/2 enzymes that catalyze the final step of CHC biosynthesis in Drosophila and Musca domestica, respectively. Immunostaining indicated that both CYP4G16 and CYP4G17 are highly abundant in oenocytes, the insect cell type thought to secrete hydrocarbons. However, an intriguing difference was indicated; CYP4G17 occurs throughout the cell, as expected for a microsomal P450, but CYP4G16 localizes to the periphery of the cell and lies on the cytoplasmic side of the cell membrane, a unique position for a P450 enzyme. CYP4G16 and CYP4G17 were functionally expressed in insect cells. CYP4G16 produced hydrocarbons from a C18 aldehyde substrate and thus has bona fide decarbonylase activity similar to that of dmCYP4G1/2. The data support the hypothesis that the coevolution of multiple mechanisms, including cuticular barriers, has occurred in highly pyrethroid-resistant An. gambiae. PMID:27439866

Human cytochrome-P450 enzymes metabolize N-(2-methoxyphenyl)hydroxylamine, a metabolite of the carcinogens o-anisidine and o-nitroanisole, thereby dictating its genotoxicity.

PubMed

Naiman, Karel; Martínková, Markéta; Schmeiser, Heinz H; Frei, Eva; Stiborová, Marie

2011-12-24

N-(2-Methoxyphenyl)hydroxylamine is a component in the human metabolism of two industrial and environmental pollutants and bladder carcinogens, viz. 2-methoxyaniline (o-anisidine) and 2-methoxynitrobenzene (o-nitroanisole), and it is responsible for their genotoxicity. Besides its capability to form three deoxyguanosine adducts in DNA, N-(2-methoxyphenyl)-hydroxylamine is also further metabolized by hepatic microsomal enzymes. To investigate its metabolism by human hepatic microsomes and to identify the major microsomal enzymes involved in this process are the aims of this study. N-(2-Methoxyphenyl)hydroxylamine is metabolized by human hepatic microsomes predominantly to o-anisidine, one of the parent carcinogens from which N-(2-methoxyphenyl)hydroxylamine is formed, while o-aminophenol and two N-(2-methoxyphenyl)hydroxylamine metabolites, whose exact structures have not been identified as yet, are minor products. Selective inhibitors of microsomal CYPs, NADPH:CYP reductase and NADH:cytochrome-b(5) reductase were used to characterize human liver microsomal enzymes reducing N-(2-methoxyphenyl)hydroxylamine to o-anisidine. Based on these studies, we attribute the main activity for this metabolic step in human liver to CYP3A4, 2E1 and 2C (more than 90%). The enzymes CYP2D6 and 2A6 also partake in this N-(2-methoxyphenyl)hydroxylamine metabolism in human liver, but only to ∼6%. Among the human recombinant CYP enzymes tested in this study, human CYP2E1, followed by CYP3A4, 1A2, 2B6 and 2D6, were the most efficient enzymes metabolizing N-(2-methoxyphenyl)hydroxylamine to o-anisidine. The results found in this study indicate that genotoxicity of N-(2-methoxyphenyl)hydroxylamine is dictated by its spontaneous decomposition to nitrenium/carbenium ions generating DNA adducts, and by its susceptibility to metabolism by CYP enzymes. Copyright © 2011 Elsevier B.V. All rights reserved.

Population pharmacokinetic analysis of cilostazol in healthy subjects with genetic polymorphisms of CYP3A5, CYP2C19 and ABCB1

PubMed Central

Yoo, Hee-Doo; Cho, Hea-Young; Lee, Yong-Bok

2010-01-01

AIMS To investigate the influence of genetic polymorphisms in the CYP3A5, CYP2C19 and ABCB1 genes on the population pharmacokinetics of cilostazol in healthy subjects. METHODS Subjects who participated in four separate cilostazol bioequivalence studies with the same protocols were included in this retrospective analysis. One hundred and four healthy Korean volunteers were orally administered a single 50- or 100-mg dose of cilostazol. We estimated the population pharmacokinetics of cilostazol using a nonlinear mixed effects modelling (nonmem) method and explored the possible influence of genetic polymorphisms in CYP3A (CYP3A5*3), CYP2C19 (CYP2C19*2 and CYP2C19*3) and ABCB1 (C1236T, G2677T/A and C3435T) on the population pharmacokinetics of cilostazol. RESULTS A two-compartment model with a first-order absorption and lag time described the cilostazol serum concentrations well. The apparent oral clearance (CL/F) was estimated to be 12.8 l h−1. The volumes of the central and the peripheral compartment were characterized as 20.5 l and 73.1 l, respectively. Intercompartmental clearance was estimated at 5.6 l h−1. Absorption rate constant was estimated at 0.24 h−1 and lag time was predicted at 0.57 h. The genetic polymorphisms of CYP3A5 had a significant (P < 0.001) influence on the CL/F of cilostazol. When CYP2C19 was evaluated, a significant difference (P < 0.01) was observed among the three genotypes (extensive metabolizers, intermediate metabolizers and poor metabolizers) for the CL/F. In addition, a combination of CYP3A5 and CYP2C19 genotypes was found to be associated with a significant difference (P < 0.005) in the CL/F. When including these genotypes, the interindividual variability of the CL/F was reduced from 34.1% in the base model to 27.3% in the final model. However, no significant differences between the ABCB1 genotypes and cilostazol pharmacokinetic parameters were observed. CONCLUSIONS The results of the present study indicate that CYP3A5 and CYP2C19 polymorphisms explain the substantial interindividual variability that occurs in the metabolism of cilostazol. PMID:20078610

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hargrove, Tatiana Y.; Wawrzak, Zdzislaw; Liu, Jialin

Leishmaniasis is a major health problem that affects populations of {approx}90 countries worldwide, with no vaccine and only a few moderately effective drugs. Here we report the structure/function characterization of sterol 14{alpha}-demethylase (CYP51) from Leishmania infantum. The enzyme catalyzes removal of the 14{alpha}-methyl group from sterol precursors. The reaction is essential for membrane biogenesis and therefore has great potential to become a target for antileishmanial chemotherapy. Although L. infantum CYP51 prefers C4-monomethylated sterol substrates such as C4-norlanosterol and obtusifoliol (V{sub max} of {approx}10 and 8 min{sup -1}, respectively), it is also found to 14{alpha}-demethylate C4-dimethylated lanosterol (V{sub max} = 0.9more » min{sup -1}) and C4-desmethylated 14{alpha}-methylzymosterol (V{sub max} = 1.9 min{sup -1}). Binding parameters with six sterols were tested, with K{sub d} values ranging from 0.25 to 1.4 {mu}m. Thus, L. infantum CYP51 is the first example of a plant-like sterol 14{alpha}-demethylase, where requirements toward the composition of the C4 atom substituents are not strict, indicative of possible branching in the postsqualene portion of sterol biosynthesis in the parasite. Comparative analysis of three CYP51 substrate binding cavities (Trypanosoma brucei, Trypanosoma cruzi, and L. infantum) suggests that substrate preferences of plant- and fungal-like protozoan CYP51s largely depend on the differences in the enzyme active site topology. These minor structural differences are also likely to underlie CYP51 catalytic rates and drug susceptibility and can be used to design potent and specific inhibitors.« less

Pharmacokinetics and pharmacodynamics following maintenance doses of prasugrel and clopidogrel in Chinese carriers of CYP2C19 variants

PubMed Central

Kelly, Ronan P; Close, Sandra L; Farid, Nagy A; Winters, Kenneth J; Shen, Lei; Natanegara, Fanni; Jakubowski, Joseph A; Ho, Mary; Walker, Joseph R; Small, David S

2012-01-01

AIMS This open-label, two-period, randomized, crossover study was designed to determine the effect of CYP2C19 reduced function variants on exposure to active metabolites of, and platelet response to, prasugrel and clopidogrel. METHODS Ninety healthy Chinese subjects, stratified by CYP2C19 phenotype, were randomly assigned to treatment with prasugrel 10 mg or clopidogrel 75 mg for 10 days followed by 14 day washout and 10 day treatment with the other drug. Eighty-three subjects completed both treatment periods. Blood samples were collected at specified time points for measurement of each drug's active metabolite (Pras-AM and Clop-AM) concentrations and determination of inhibition of platelet aggregation (IPA) by light transmittance aggregometry. CYP2C19 genotypes were classified into three predicted phenotype groups: rapid metabolizers [RMs (*1/*1)], heterozygous or intermediate metabolizers [IMs (*1/*2, *1/*3)] and poor metabolizers [PMs (*2/*2, *2/*3)]. RESULTS Pras-AM exposure was similar in IMs and RMs (90% CI 0.85, 1.03) and slightly lower in PMs than IMs (90% CI 0.74, 0.99), whereas Clop-AM exposure was significantly lower in IMs compared with RMs (90% CI 0.62, 0.83), and in PMs compared with IMs (90% CI 0.53, 0.82). IPA was more consistent among RMs, IMs and PMs in prasugrel treated subjects (80.2%, 84.2% and 80.2%, respectively) than in clopidogrel treated subjects (59.7%, 56.2% and 36.8%, respectively; P < 0.001). CONCLUSIONS Prasugrel demonstrated higher active metabolite exposure and more consistent pharmacodynamic response across all three predicted phenotype groups compared with clopidogrel, confirming observations from previous research that CYP2C19 phenotype plays an important role in variability of response to clopidogrel, but has no impact on response to prasugrel. PMID:21689142

Tissue Specific Modulation of cyp2c and cyp3a mRNA Levels and Activities by Diet-Induced Obesity in Mice: The Impact of Type 2 Diabetes on Drug Metabolizing Enzymes in Liver and Extra-Hepatic Tissues

PubMed Central

Chamoun, Michel; Gravel, Sophie; Turgeon, Jacques; Michaud, Veronique

2017-01-01

Various diseases such as type 2 diabetes (T2D) may alter drug clearance. The objective of this study was to evaluate the effects of T2D on CYP450 expressions and activities using high-fat diet (HFD) as a model of obesity-dependent diabetes in C57BL6 mice. The cyp450 mRNA expression levels for 15 different isoforms were determined in the liver and extra-hepatic tissues (kidneys, lungs and heart) of HFD-treated animals (n = 45). Modulation of cyp450 metabolic activities by HFD was assessed using eight known substrates for specific human ortholog CYP450 isoforms: in vitro incubations were conducted with liver and extra-hepatic microsomes. Expression levels of cyp3a11 and cyp3a25 mRNA were decreased in the liver (>2–14-fold) and kidneys (>2-fold) of HFD groups which correlated with a significant reduction in midazolam metabolism (by 21- and 5-fold in hepatic and kidney microsomes, respectively, p < 0.001). HFD was associated with decreased activities of cyp2b and cyp2c subfamilies in all organs tested except in the kidneys (for tolbutamide). Other cyp450 hepatic activities were minimally or not affected by HFD. Taken together, our data suggest that substrate-dependent and tissue-dependent modulation of cyp450 metabolic capacities by early phases of T2D are observed, which could modulate drug disposition and pharmacological effects in various tissues. PMID:28954402

Substrate preferences and catalytic parameters determined by structural characteristics of sterol 14alpha-demethylase (CYP51) from Leishmania infantum.

PubMed

Hargrove, Tatiana Y; Wawrzak, Zdzislaw; Liu, Jialin; Nes, W David; Waterman, Michael R; Lepesheva, Galina I

2011-07-29

Leishmaniasis is a major health problem that affects populations of ∼90 countries worldwide, with no vaccine and only a few moderately effective drugs. Here we report the structure/function characterization of sterol 14α-demethylase (CYP51) from Leishmania infantum. The enzyme catalyzes removal of the 14α-methyl group from sterol precursors. The reaction is essential for membrane biogenesis and therefore has great potential to become a target for antileishmanial chemotherapy. Although L. infantum CYP51 prefers C4-monomethylated sterol substrates such as C4-norlanosterol and obtusifoliol (V(max) of ∼10 and 8 min(-1), respectively), it is also found to 14α-demethylate C4-dimethylated lanosterol (V(max) = 0.9 min(-1)) and C4-desmethylated 14α-methylzymosterol (V(max) = 1.9 min(-1)). Binding parameters with six sterols were tested, with K(d) values ranging from 0.25 to 1.4 μM. Thus, L. infantum CYP51 is the first example of a plant-like sterol 14α-demethylase, where requirements toward the composition of the C4 atom substituents are not strict, indicative of possible branching in the postsqualene portion of sterol biosynthesis in the parasite. Comparative analysis of three CYP51 substrate binding cavities (Trypanosoma brucei, Trypanosoma cruzi, and L. infantum) suggests that substrate preferences of plant- and fungal-like protozoan CYP51s largely depend on the differences in the enzyme active site topology. These minor structural differences are also likely to underlie CYP51 catalytic rates and drug susceptibility and can be used to design potent and specific inhibitors.

Geraniol hydroxylase and hydroxygeraniol oxidase activities of the CYP76 family of cytochrome P450 enzymes and potential for engineering the early steps of the (seco)iridoid pathway.

PubMed

Höfer, René; Dong, Lemeng; André, François; Ginglinger, Jean-François; Lugan, Raphael; Gavira, Carole; Grec, Sebastien; Lang, Gerhard; Memelink, Johan; Van der Krol, Sander; Bouwmeester, Harro; Werck-Reichhart, Danièle

2013-11-01

The geraniol-derived (seco)iridoid skeleton is a precursor for a large group of bioactive compounds with diverse therapeutic applications, including the widely used anticancer molecule vinblastine. Despite of this economic prospect, the pathway leading to iridoid biosynthesis from geraniol is still unclear. The first geraniol hydroxylation step has been reported to be catalyzed by cytochrome P450 enzymes such as CYP76B6 from Catharanthus roseus and CYP76C1 from Arabidopsis thaliana. In the present study, an extended functional analysis of CYP76 family members was carried-out to identify the most effective enzyme to be used for pathway reconstruction. This disproved CYP76C1 activity and led to the characterization of CYP76C4 from A. thaliana as a geraniol 9- or 8-hydroxylase. CYP76B6 emerged as a highly specialized multifunctional enzyme catalyzing two sequential oxidation steps leading to the formation of 8-oxogeraniol from geraniol. This dual function was confirmed in planta using a leaf-disc assay. The first step, geraniol hydroxylation, was very efficient and fast enough to outcompete geraniol conjugation in plant tissues. When the enzyme was expressed in leaf tissues, 8-oxogeraniol was converted into further oxidized and/or reduced compounds in the absence of the next enzyme of the iridoid pathway. Copyright © 2013 International Metabolic Engineering Society. Published by Elsevier Inc. All rights reserved.

A Structural Model of a P450-Ferredoxin Complex from Orientation-Selective Double Electron-Electron Resonance Spectroscopy.

PubMed

Bowen, Alice M; Johnson, Eachan O D; Mercuri, Francesco; Hoskins, Nicola J; Qiao, Ruihong; McCullagh, James S O; Lovett, Janet E; Bell, Stephen G; Zhou, Weihong; Timmel, Christiane R; Wong, Luet Lok; Harmer, Jeffrey R

2018-02-21

Cytochrome P450 (CYP) monooxygenases catalyze the oxidation of chemically inert carbon-hydrogen bonds in diverse endogenous and exogenous organic compounds by atmospheric oxygen. This C-H bond oxy-functionalization activity has huge potential in biotechnological applications. Class I CYPs receive the two electrons required for oxygen activation from NAD(P)H via a ferredoxin reductase and ferredoxin. The interaction of Class I CYPs with their cognate ferredoxin is specific. In order to reconstitute the activity of diverse CYPs, structural characterization of CYP-ferredoxin complexes is necessary, but little structural information is available. Here we report a structural model of such a complex (CYP199A2-HaPux) in frozen solution derived from distance and orientation restraints gathered by the EPR technique of orientation-selective double electron-electron resonance (os-DEER). The long-lived oscillations in the os-DEER spectra were well modeled by a single orientation of the CYP199A2-HaPux complex. The structure is different from the two known Class I CYP-Fdx structures: CYP11A1-Adx and CYP101A1-Pdx. At the protein interface, HaPux residues in the [Fe 2 S 2 ] cluster-binding loop and the α3 helix and the C-terminus residue interact with CYP199A2 residues in the proximal loop and the C helix. These residue contacts are consistent with biochemical data on CYP199A2-ferredoxin binding and electron transfer. Electron-tunneling calculations indicate an efficient electron-transfer pathway from the [Fe 2 S 2 ] cluster to the heme. This new structural model of a CYP-Fdx complex provides the basis for tailoring CYP enzymes for which the cognate ferredoxin is not known, to accept electrons from HaPux and display monooxygenase activity.

Impact of genetic factors (VKORC1, CYP2C9, CYP4F2 and EPHX1) on the anticoagulation response to fluindione

PubMed Central

Lacut, Karine; Ayme-Dietrich, Estelle; Gourhant, Lenaick; Poulhazan, Elise; Andro, Marion; Becquemont, Laurent; Mottier, Dominique; Le Gal, Gregoire; Verstuyft, Celine

2012-01-01

AIM Genetic variants of the enzyme that metabolizes warfarin, cytochrome P-450 2C9 (CYP2C9) and of a key pharmacologic target of vitamin K antagonists, vitamin K epoxide reductase (VKORC1), contribute to differences in patients' responses to coumarin derivatives. The role of these variants in fluindione response is unknown. Our aim was to assess whether genetic factors contribute to the variability in the response to fluindione. METHODS Four hundred sixty-five patients with a venous thromboembolic event treated by fluindione for at least 3 months with a target international normalized ratio (INR) of 2.0 to 3.0 were studied. VKORC1, CYP2C9, CYP4F2 and EPHX1 genotypes were assessed. INR checks, fluindione doses and bleeding events were collected. RESULTS VKORC1 genotype had a significant impact on early anticoagulation (INR value ≥2 after the first two intakes) (P < 0.0001), on the time required to reach a first INR within the therapeutic range (P < 0.0001) and on the time to obtain a first INR value > 4 (P = 0.0002). The average daily dose of fluindione during the first period of stability was significantly associated with the VKORC1 genotype: 19.8 mg (±5.5) for VKORC1 CC, 14.7 mg (±6.2) for VKORC1 CT and 8.2 mg (±2.5) for VKORC1 TT (P < 0.0001). CYP2C9, CYP4F2 and EPHX1 genotypes did not significantly influence the response to fluindione. CONCLUSIONS VKORC1 genotype strongly affected anticoagulation induced by fluindione whereas CYP2C9, CYP4F2 and EPHX1 genotypes seemed less determining. PMID:21883387

Evaluation of the relationship between polymorphisms in CYP2C19 and the pharmacokinetics of omeprazole, pantoprazole and rabeprazole.

PubMed

Román, Manuel; Ochoa, Dolores; Sánchez-Rojas, Sergio Daniel; Talegón, Maria; Prieto-Pérez, Rocio; Rivas, Ângela; Abad-Santos, Francisco; Cabaleiro, Teresa

2014-01-01

To evaluate the possible association between polymorphisms in CYP2C19 and the pharmacokinetics of omeprazole, rabeprazole and pantoprazole. 151 healthy volunteers were evaluated for polymorphisms in the CYP2C19 gene using real-time polymerase chain reaction. Plasma concentrations were measured using high-performance liquid chromatography coupled to mass spectrometry. Carriers of the *2 allele displayed poor metabolism for all the PPIs studied (around 50% decrease in clearance). Subjects with the *17 allele showed a light increase in clearance compared with *1/*1 (not significant). CYP2C19*2 is associated with decreased clearance of all the PPIs, that could be associated with higher drug efficacy. CYP2C19*17 could increase clearance of these drugs, although the effect seems small.

The effects of milk thistle (Silybum marianum) on human cytochrome P450 activity.

PubMed

Kawaguchi-Suzuki, Marina; Frye, Reginald F; Zhu, Hao-Jie; Brinda, Bryan J; Chavin, Kenneth D; Bernstein, Hilary J; Markowitz, John S

2014-10-01

Milk thistle (Silybum marianum) extracts are widely used as a complementary and alternative treatment of various hepatic conditions and a host of other diseases/disorders. The active constituents of milk thistle supplements are believed to be the flavonolignans contained within the extracts. In vitro studies have suggested that some milk thistle components may significantly inhibit specific cytochrome P450 (P450) enzymes. However, determining the potential for clinically significant drug interactions with milk thistle products has been complicated by inconsistencies between in vitro and in vivo study results. The aim of the present study was to determine the effect of a standardized milk thistle supplement on major P450 drug-metabolizing enzymes after a 14-day exposure period. CYP1A2, CYP2C9, CYP2D6, and CYP3A4/5 activities were measured by simultaneously administering the four probe drugs, caffeine, tolbutamide, dextromethorphan, and midazolam, to nine healthy volunteers before and after exposure to a standardized milk thistle extract given thrice daily for 14 days. The three most abundant falvonolignans found in plasma, following exposure to milk thistle extracts, were silybin A, silybin B, and isosilybin B. The concentrations of these three major constituents were individually measured in study subjects as potential perpetrators. The peak concentrations and areas under the time-concentration curves of the four probe drugs were determined with the milk thistle administration. Exposure to milk thistle extract produced no significant influence on CYP1A2, CYP2C9, CYP2D6, or CYP3A4/5 activities. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

In vitro assessment of 39 CYP2C9 variants found in the Chinese population on the metabolism of the model substrate fluoxetine and a summary of their effects on other substrates.

PubMed

Ji, Y; Chen, S; Zhao, L; Pan, P; Wang, L; Cai, J; Dai, D; Hu, G; Cai, J P; Huang, H

2015-06-01

Cytochrome P450 2C9 (CYP2C9) is a polymorphic enzyme that is responsible for clearing approximately 15% of clinically important drugs. The objective of this study was to assess the catalytic characteristics of 39 CYP2C9 isoforms found in the Chinese population and their effects on the metabolism of the model substrate fluoxetine in vitro. Baculovirus-mediated expressing system was used to highly express wild-type and the 38 CYP2C9 allelic variants in insect cell microsomes. Then, the enzymatic characteristics of each variant were evaluated using fluoxetine as the substrate. Reactions were performed at 37 °C with the insect microsomes and 10-200 μm fluoxetine for 60 min. After termination, the products were precipitated and used for signal collection by UPLC-MS/MS. Of the 39 tested CYP2C9 isoforms, only four variants (CYP2C9*3, CYP2C9*27, CYP2C9*34 and CYP2C9*37) exhibited similar relative clearance values to that of the wild-type CYP2C9*1. Moreover, five variants (CYP2C9*14, CYP2C9*36, CYP2C9*45, CYP2C9*48 and CYP2C9*55) showed a higher intrinsic clearance value than the wild-type protein, whereas the remaining 29 CYP2C9 isoforms exhibited significantly decreased clearance values (from 6·23% to 87·74%) compared to CYP2C9*1. In addition, 28 CYP2C9 isoforms including CYP2C9*3 exhibited a trend towards substrate inhibition for fluoxetine. This study provides the most comprehensive data on the enzymatic activities associated with all reported CYP2C9 variants in the Chinese population with regard to the widely used antidepressant drug, fluoxetine. Our data indicate that more attention should be paid to subjects carrying the corresponding infrequent CYP2C9 alleles when administering fluoxetine in the clinic. © 2015 John Wiley & Sons Ltd.

Sex difference in the principal cytochrome P-450 for tributyltin metabolism in rats

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ohhira, Shuji; Enomoto, Mitsunori; Matsui, Hisao

Tributyltin is metabolized by cytochrome P-450 (CYP) system enzymes, and its metabolic fate may contribute to the toxicity of the chemical. In the present study, it is examined whether sex differences in the metabolism of tributyltin exist in rats. In addition, the in vivo and in vitro metabolism of tributyltin was investigated using rat hepatic CYP systems to confirm the principal CYP involved. A significant sex difference in metabolism occurred both in vivo and in vitro, suggesting that one of the CYPs responsible for tributyltin metabolism in rats is male specific or predominant at least. Eight cDNA-expressed rat CYPs, includingmore » typical phenobarbital (PB)-inducible forms and members of the CYP2C subfamily, were tested to determine their capability for tributyltin metabolism. Among the enzymes studied, a statistically significant dealkylation of tributyltin was mediated by CYP2C6 and 2C11. Furthermore, the sex difference in metabolism disappeared in vitro after anti-rat CYP2C11 antibody pretreatment because CYP2C11 is a major male-specific form in rats. These results indicate that CYP2C6 is the principal CYP for tributyltin metabolism in female rats, whereas CYP2C11 as well as 2C6 is involved in tributyltin metabolism in male rats, and it is suggested that CYP2C11 is responsible for the significant sex difference in the metabolism of tributyltin observed in rats.« less

Pharmacogenomics of Anti-platelet Therapy: How much evidence is enough for clinical implementation?

PubMed Central

Perry, Christina G.; Shuldiner, Alan R.

2013-01-01

Pharmacogenomics, the study of the genomics of drug response and adverse effects, holds great promise for more effective individualized (personalized) medicine. Recent evidence supports a role of loss-of-function variants in the cytochrome P450 enzyme CYP2C19 as a determinant of clopidogrel response. Those who carry loss-of-function variants do not metabolize clopidogrel, a prodrug, into its active form resulting in decreased inhibition of platelet function and a higher likelihood of recurrent cardiovascular events. Despite a large body of evidence supporting clinical utility, adoption of anti-platelet pharmacogenetics into clinical practice has been slow. In this review, we summarize the pharmacokinetic, pharmacodynamics, and clinical evidence, identify gaps in knowledge and other barriers that appear to be slowing adoption, and describe CYP2C19 pharmacogenetics implementation projects currently underway. Only when we surmount these barriers will the astute clinician be able to use pharmacogenetic information in conjunction with the history, physical exam, and other medical tests and information to choose the most efficacious anti-platelet therapy for each individual patient. PMID:23697979

Idiopathic hirsutism: local and peripheral expression of aromatase (CYP19A) and 5α-reductase genes (SRD5A1 and SRD5A2).

PubMed

Caglayan, A Okay; Dundar, Munis; Tanriverdi, Fatih; Baysal, Nuran A; Unluhizarci, Kursad; Ozkul, Yusuf; Borlu, Murat; Batukan, Cem; Kelestimur, Fahrettin

2011-08-01

To evaluate idiopathic hirsutism etiology via molecular studies testing peripheral and local aromatase and 5α-reductase expression. Assessment of the expression of messenger RNA (mRNA) for type 1 and 2,5α-reductase isoenzyme gene (SDR5A1, SDR5A2) and aromatase (CYP19A) in dermal papillae cells and peripheral blood mononuclear cells. University hospital. 28 untreated idiopathic hirsute patients and 20 healthy women (controls). Human skin biopsies and peripheral venous blood. SDR5A1, SDR5A2, CYP19A gene expression in skin biopsies and peripheral blood. A statistically significant reduction of SRD5A1, SRD5A2, and CYP19A gene expression was found in the dermal papillae cells and peripheral blood mononuclear cell between the study and control group. Further study, including protein expression and enzyme activity assays, are warranted to characterize the paradoxically low gene expression levels of local 5α-reductase and aromatase in women with idiopathic hirsutism. Copyright © 2011 American Society for Reproductive Medicine. Published by Elsevier Inc. All rights reserved.

A comparison of 2-phenyl-2-(1-piperidinyl)propane (ppp), 1,1',1''-phosphinothioylidynetrisaziridine (thioTEPA), clopidogrel, and ticlopidine as selective inactivators of human cytochrome P450 2B6.

PubMed

Walsky, Robert L; Obach, R Scott

2007-11-01

The use of selective chemical inhibitors of human cytochrome P450 (P450) enzymes represents a powerful method by which the relative contributions of various human P450 enzymes to the metabolism of drugs can be determined. However, the identification of CYP2B6 in the metabolism of drugs has been more challenging because of the lack of a well established inhibitor of this enzyme. In this report, we describe the selectivity of 2-phenyl-2-(1-piperidinyl)propane (PPP) as an inactivator of CYP2B6 and compare this selectivity versus other CYP2B6 inactivators: 1,1',1''-phosphinothioylidynetrisaziridine (thioTEPA), clopidogrel, and ticlopidine. Values of K(I) and k(inact) for PPP were 5.6 microM and 0.13/min for bupropion hydroxylase catalyzed by pooled human liver microsomes, and values for thioTEPA were similar (4.8 microM and 0.20/min, respectively). Intrinsic inactivation capability was considerably greater for clopidogrel because of a greater k(inact) value (1.9/min). Ticlopidine was potent with K(I) and k(inact) values of 0.32 microM and 0.43/min, respectively. The selectivity of these four agents for CYP2B6 was determined by testing their effects on other human P450 enzyme activities using conditions that yield approximately 90% inactivation of CYP2B6 activity. The results showed that preincubation of human liver microsomes with PPP at 30 microM for 30 min provided more selective inhibition for CYP2B6 than thioTEPA, clopidogrel, and ticlopidine. Furthermore, the use of clopidogrel is complicated by the observation that this agent is not stable in the presence of human liver microsomes, even without addition of NADPH. Therefore, PPP can serve as a selective chemical inactivator of CYP2B6 and be used to define the role of CYP2B6 in the metabolism of drugs.

EVALUATION OF THE AROMATASE INHIBITOR FADROZOLE IN A SHORT-TERM REPRODUCTION ASSAY WITH THE FATHEAD MINNOW (PIMEPHALES PROMELAS)

EPA Science Inventory

Cytochrome P450 aromatase is a key enzyme in vertebrate steroidogenesis, catalyzing the conversion of C19 androgens to C18 estrogens such a B-estradiol (E2). The objective of this study was to assess effects of the CYP inhibitor fadrozole on fathead minnow reproductive endocrinol...

Inhibition of human P450 enzymes by natural extracts used in traditional medicine.

PubMed

Rodeiro, Idania; Donato, María T; Jimenez, Nuria; Garrido, Gabino; Molina-Torres, Jorge; Menendez, Roberto; Castell, José V; Gómez-Lechón, María J

2009-02-01

Different medicinal plants are widely used in Cuba and Mexico to treat several disorders. This paper reports in vitro inhibitory effects on the P450 system of herbal products commonly used by people in Cuba and Mexico in traditional medicine for decades. Experiments were conducted in human liver microsomes. The catalytic activities of CYP1A1/2, 2D6, and 3A4 were measured using specific probe substrates. The Heliopsis longipes extract exhibited a concentration-dependent inhibition of the three enzymes, and similar effects were produced by affinin (an alkamide isolated from the H. longipes extract) and two catalytically reduced alkamides. Mangifera indica L. and Thalassia testudinum extracts, two natural polyphenol-rich extracts, diminished CYP1A1/2 and 3A4 activities, but not the CYP2D6 activity. These results suggest that these herbs inhibit the major human P450 enzymes involved in drug metabolism and could induce potential herbal-drug interactions. Copyright (c) 2008 John Wiley & Sons, Ltd.

Re-engineering of CYP2C9 to probe acid-base substrate selectivity.

PubMed

Tai, Guoying; Dickmann, Leslie J; Matovic, Nicholas; DeVoss, James J; Gillam, Elizabeth M J; Rettie, Allan E

2008-10-01

A common feature of many CYP2C9 ligands is their weak acidity. As revealed by crystallography, the structural basis for this behavior involves a charge-pairing interaction between an anionic moiety on the substrate and an active site R108 residue. In the present study we attempted to re-engineer CYP2C9 to better accept basic ligands by charge reversal at this key residue. We expressed and purified the R108E and R108E/D293N mutants and compared their ability with that of native CYP2C9 to interact with (S)-warfarin, diclofenac, pyrene, propranolol, and ibuprofen amine. As expected, the R108E mutant maintained all the native enzyme's pyrene 1-hydroxylation activity, but catalytic activity toward diclofenac and (S)-warfarin was abrogated. In contrast, the double mutant displayed much less selectivity in its behavior toward these control ligands. Neither of the mutants displayed significant enhancement of propranolol metabolism, and all three preparations exhibited a type II (inhibitor) rather than type I (substrate) spectrum with ibuprofen amine, although binding became progressively weaker with the single and double mutants. Collectively, these data underscore the importance of the amino acid at position 108 in the acid substrate selectivity of CYP2C9, highlight the accommodating nature of the CYP2C9 active site, and provide a cautionary note regarding facile re-engineering of these complex cytochrome P450 active sites.

Re-engineering of CYP2C9 to Probe Acid-Base Substrate Selectivity

PubMed Central

Tai, Guoying; Dickmann, Leslie J.; Matovic, Nicholas; DeVoss, James J.; Gillam, Elizabeth M. J.; Rettie, Allan E.

2009-01-01

A common feature of many CYP2C9 ligands is their weak acidity. As revealed by crystallography, the structural basis for this behavior involves a charge-pairing interaction between an anionic moiety on the substrate and an active site R108 residue. In the present study we attempted to re-engineer CYP2C9 to better accept basic ligands by charge reversal at this key residue. We expressed and purified the R108E and R108E/D293N mutants and compared their ability with that of native CYP2C9 to interact with (S)-warfarin, diclofenac, pyrene, propranolol, and ibuprofen amine. As expected, the R108E mutant maintained all the native enzyme's pyrene 1-hydroxylation activity, but catalytic activity toward diclofenac and (S)-warfarin was abrogated. In contrast, the double mutant displayed much less selectivity in its behavior toward these control ligands. Neither of the mutants displayed significant enhancement of propranolol metabolism, and all three preparations exhibited a type II (inhibitor) rather than type I (substrate) spectrum with ibuprofen amine, although binding became progressively weaker with the single and double mutants. Collectively, these data underscore the importance of the amino acid at position 108 in the acid substrate selectivity of CYP2C9, highlight the accommodating nature of the CYP2C9 active site, and provide a cautionary note regarding facile re-engineering of these complex cytochrome P450 active sites. PMID:18606741

Inhibition of Human Cytochrome P450 2c8-catalyzed Amodiaquine N-desethylation: Effect of Five Traditionally and Commonly Used Herbs

PubMed Central

Muthiah, Yasotha Devi; Ong, Chin Eng; Sulaiman, Siti Amrah; Ismail, Rusli

2016-01-01

Background: In Southeast Asia and many parts of the world, herbal products are increasingly used in parallel with modern medicine. Objective: This study aimed to investigate the effects of herbs commonly used in Southeast Asia on activity of cytochrome P450 2C8 (CYP2C8), an important human hepatic enzyme in drug metabolism. Materials and Methods: The selected herbs, such as Eurycoma longifolia Jack (ELJ), Labisia pumila (LP), Echinacea purpurea (EP), Andrographis paniculata (AP), and Ginkgo biloba (GB), were subjected to inhibition studies using an in vitro CYP2C8 activity marker, amodiaquine N-desethylase assay. Inhibition parameters, inhibitory concentration 50% (IC50), and Ki values were determined to study the potency and mode of inhibition. Results: All herbs inhibited CYP2C8 with the following order of potency: LP > ELJ > GB > AP > EP. LP and ELJ inhibited potently at Ki's of 2 and 4 times the Ki of quercetin, the positive control. The inhibition by LP was uncompetitive in nature as compared to competitive or mixed type inhibition observed with other herbs. GB exhibited moderate inhibitory effect at a Ki6 times larger than quercetin Ki. AP and EP, on the other hand, showed only weak inhibition. Conclusion: The herbs we chose represented the more commonly used herbs in Southeast Asia where collision of tradition and modernization in healthcare, if not properly managed, may lead to therapeutic misadventures. We conclude that concurrent consumption of some herbs, in particular, LP and ELJ, may have relevance in drug-herb interactions via CYP2C8 inhibition in vivo. SUMMARY Herbs are increasingly used in parallel with modern medicines nowadays. In this study five commonly used herbs in Southeast Asia region, ELJ, LP, EP, AP and GB, were investigated for their in vitro inhibitory potency on CYP2C8, an important drug-metaboliz-ing human hepatic enzyme. All herbs inhibited CYP2C8 activity marker, amodiaquine N-desethylation, with potency order of LP > ELJ > GB >AP > EP. LP, ELJ and GB exhibited Ki values of 2, 4 and 6 times the Ki of quercetin, the positive control, indicating potent to moderate degree of enzyme inhibition. AP and EP, on the other hand, showed only weak inhibition. In summary, concurrent consumption of some herbs especially LP and ELJ may have relevance in drug-herb interactions via CYP2C8 inhibition in vivo. Abbreviations Used: AQ: Amodiaquine, AP: Andrographis paniculata, CYP: Cytochrome P450, DEAQ: Desethylamodiaquine, EP: Echinacea purpurea, ELJ: Eurycoma longifolia Jack, GB: Ginkgo biloba, Ki: Inhibition constant, LP: Labisia pumila, Vmax: Maximal velocity, Km: Michaelis-Menten constant. PMID:27695271

Cloning of cytochrome P450 3A137 complementary DNA in silver carp and expression induction by ionic liquid.

PubMed

Li, Xiaoyu; Ma, Junguo; Lei, Wenlong; Li, Jie; Zhang, Yaning; Li, Yuanlong

2013-08-01

Cytochrome P450 (CYP) enzymes, especially CYP 3A, are responsible for metabolizing of various kinds of endogenous and exogenous compounds in animals. In the present study, a full-length sequence of CYP 3A137 cDNA in silver carp was cloned and sequenced, and then a phylogenetic tree of CYP 3A was structured. Additionally, the acute toxicity of the ionic liquid 1-octyl-3-methylimidazolium bromide ([C8mim]Br) on silver carp and transcription and microsome enzyme activity of CYP 3A137 in the liver of silver fish after rifampicin or [C8mim]Br exposure were also determined in this study. The results show that the full length of CYP 3A137 cDNA is 1810 base pair (bp) long and contains an open reading frame of 1539bp encoding a protein of 513 amino acids. Sequence analysis reveals that CYP 3A137 is highly conserved in fish. Moreover, the results of quantitative real-time polymerase chain reaction reveal that CYP 3A137 in silver carp is constitutively expressed in all tissues examined and the sequence of expression rate is liver>intestine>kidney>spleen>brain>heart>muscle. Finally, the results of acute toxicity tests indicate that both rifampicin and [C8mim]Br significantly up-regulate the expression of CYP 3A137 at mRNA level and increase CYP 3A137 enzyme activity in fish liver, suggesting that CYP 3A137 be involved in metabolism of [C8mim]Br in silver carp. Copyright © 2013 Elsevier Ltd. All rights reserved.

Significantly decreased and more variable expression of major CYPs and UGTs in liver microsomes prepared from HBV-positive human hepatocellular carcinoma and matched pericarcinomatous tissues determined using an isotope label-free UPLC-MS/MS method.

PubMed

Yan, Tongmeng; Gao, Song; Peng, Xiaojuan; Shi, Jian; Xie, Cong; Li, Qiang; Lu, Linlin; Wang, Ying; Zhou, Fuyuan; Liu, Zhongqiu; Hu, Ming

2015-03-01

To determine the liver expression of cytochrome P450 (CYPs) and uridine 5'-diphosphate-glucuronosyltransferases (UGTs), the major phase I and II metabolism enzymes responsible for clearance and detoxification of drugs, xenobiotic and endogenous substances. A validated isotope label-free method was established for absolute and simultaneous quantification of 9 CYPs (1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D, 2E1 and 3A4) and 5 UGTs (1A1, 1A4, 1A6, 1A9 and 2B7) in human liver microsomes using LC-MS/MS. The LC-MS/MS method displayed excellent dynamic range (at least 250-fold) and high sensitivity for each of the signature peptides with acceptable recovery, accuracy and precision. The protein expression profile of CYP and UGT isoforms were then determined in match microsomes samples prepared from patients with HBV-positive human hepatocellular carcinoma (HCC). In the tumor microsomes, the average absolute amounts of 8 major CYP isoforms (except CYP2C19) and 3 UGT isoforms (UGT1A1, UGT1A4 and UGT2B7) were decreased significantly (p < 0.05), whereas UGT1A6 and UGT1A9 levels were unchanged (p > 0.05). In addition, among isoforms with altered expression, 6 of 8 CYP isoforms and all three UGT isoforms were much more variable in tumor microsomes. Lastly, the importance of CYP3A4 was greatly diminished whereas the importance of UGT1A6 was enhanced in tumor microsomes. The use of an isotope label-free absolute quantification method for the simultaneous determination of 9 CYPs and 5 UGTs in human liver microsomes reveals that expression levels of CYPs and UGTs in human liver are severely impact by HCC, which could impact drug metabolism, disposition and pharmacotherapy.

Strategies for Determining Correct Cytochrome P450 Contributions in Hepatic Clearance Predictions: In Vitro-In Vivo Extrapolation as Modelling Approach and Tramadol as Proof-of Concept Compound.

PubMed

T'jollyn, Huybrecht; Snoeys, Jan; Van Bocxlaer, Jan; De Bock, Lies; Annaert, Pieter; Van Peer, Achiel; Allegaert, Karel; Mannens, Geert; Vermeulen, An; Boussery, Koen

2017-06-01

Although the measurement of cytochrome P450 (CYP) contributions in metabolism assays is straightforward, determination of actual in vivo contributions might be challenging. How representative are in vitro for in vivo CYP contributions? This article proposes an improved strategy for the determination of in vivo CYP enzyme-specific metabolic contributions, based on in vitro data, using an in vitro-in vivo extrapolation (IVIVE) approach. Approaches are exemplified using tramadol as model compound, and CYP2D6 and CYP3A4 as involved enzymes. Metabolism data for tramadol and for the probe substrates midazolam (CYP3A4) and dextromethorphan (CYP2D6) were gathered in human liver microsomes (HLM) and recombinant human enzyme systems (rhCYP). From these probe substrates, an activity-adjustment factor (AAF) was calculated per CYP enzyme, for the determination of correct hepatic clearance contributions. As a reference, tramadol CYP contributions were scaled-back from in vivo data (retrograde approach) and were compared with the ones derived in vitro. In this view, the AAF is an enzyme-specific factor, calculated from reference probe activity measurements in vitro and in vivo, that allows appropriate scaling of a test drug's in vitro activity to the 'healthy volunteer' population level. Calculation of an AAF, thus accounts for any 'experimental' or 'batch-specific' activity difference between in vitro HLM and in vivo derived activity. In this specific HLM batch, for CYP3A4 and CYP2D6, an AAF of 0.91 and 1.97 was calculated, respectively. This implies that, in this batch, the in vitro CYP3A4 activity is 1.10-fold higher and the CYP2D6 activity 1.97-fold lower, compared to in vivo derived CYP activities. This study shows that, in cases where the HLM pool does not represent the typical mean population CYP activities, AAF correction of in vitro metabolism data, optimizes CYP contributions in the prediction of hepatic clearance. Therefore, in vitro parameters for any test compound, obtained in a particular batch, should be corrected with the AAF for the respective enzymes. In the current study, especially the CYP2D6 contribution was found, to better reflect the average in vivo situation. It is recommended that this novel approach is further evaluated using a broader range of compounds.

Computational Identification of the Paralogs and Orthologs of Human Cytochrome P450 Superfamily and the Implication in Drug Discovery

PubMed Central

Pan, Shu-Ting; Xue, Danfeng; Li, Zhi-Ling; Zhou, Zhi-Wei; He, Zhi-Xu; Yang, Yinxue; Yang, Tianxin; Qiu, Jia-Xuan; Zhou, Shu-Feng

2016-01-01

The human cytochrome P450 (CYP) superfamily consisting of 57 functional genes is the most important group of Phase I drug metabolizing enzymes that oxidize a large number of xenobiotics and endogenous compounds, including therapeutic drugs and environmental toxicants. The CYP superfamily has been shown to expand itself through gene duplication, and some of them become pseudogenes due to gene mutations. Orthologs and paralogs are homologous genes resulting from speciation or duplication, respectively. To explore the evolutionary and functional relationships of human CYPs, we conducted this bioinformatic study to identify their corresponding paralogs, homologs, and orthologs. The functional implications and implications in drug discovery and evolutionary biology were then discussed. GeneCards and Ensembl were used to identify the paralogs of human CYPs. We have used a panel of online databases to identify the orthologs of human CYP genes: NCBI, Ensembl Compara, GeneCards, OMA (“Orthologous MAtrix”) Browser, PATHER, TreeFam, EggNOG, and Roundup. The results show that each human CYP has various numbers of paralogs and orthologs using GeneCards and Ensembl. For example, the paralogs of CYP2A6 include CYP2A7, 2A13, 2B6, 2C8, 2C9, 2C18, 2C19, 2D6, 2E1, 2F1, 2J2, 2R1, 2S1, 2U1, and 2W1; CYP11A1 has 6 paralogs including CYP11B1, 11B2, 24A1, 27A1, 27B1, and 27C1; CYP51A1 has only three paralogs: CYP26A1, 26B1, and 26C1; while CYP20A1 has no paralog. The majority of human CYPs are well conserved from plants, amphibians, fishes, or mammals to humans due to their important functions in physiology and xenobiotic disposition. The data from different approaches are also cross-validated and validated when experimental data are available. These findings facilitate our understanding of the evolutionary relationships and functional implications of the human CYP superfamily in drug discovery. PMID:27367670

Effect of Single Nucleotide Polymorphisms in Cytochrome P450 Isoenzyme and N-Acetyltransferase 2 Genes on the Metabolism of Artemisinin-Based Combination Therapies in Malaria Patients from Cambodia and Tanzania

PubMed Central

Staehli Hodel, Eva Maria; Csajka, Chantal; Ariey, Frédéric; Guidi, Monia; Kabanywanyi, Abdunoor Mulokozi; Duong, Socheat; Decosterd, Laurent Arthur; Olliaro, Piero; Genton, Blaise

2013-01-01

The pharmacogenetics of antimalarial agents are poorly known, although the application of pharmacogenetics might be critical in optimizing treatment. This population pharmacokinetic-pharmacogenetic study aimed at assessing the effects of single nucleotide polymorphisms (SNPs) in cytochrome P450 isoenzyme genes (CYP, namely, CYP2A6, CYP2B6, CYP2C8, CYP2C9, CYP2C19, CYP2D6, CYP3A4, and CYP3A5) and the N-acetyltransferase 2 gene (NAT2) on the pharmacokinetics of artemisinin-based combination therapies in 150 Tanzanian patients treated with artemether-lumefantrine, 64 Cambodian patients treated with artesunate-mefloquine, and 61 Cambodian patients treated with dihydroartemisinin-piperaquine. The frequency of SNPs varied with the enzyme and the population. Higher frequencies of mutant alleles were found in Cambodians than Tanzanians for CYP2C9*3, CYP2D6*10 (100C→T), CYP3A5*3, NAT2*6, and NAT2*7. In contrast, higher frequencies of mutant alleles were found in Tanzanians for CYP2D6*17 (1023C→T and 2850C→T), CYP3A4*1B, NAT2*5, and NAT2*14. For 8 SNPs, no significant differences in frequencies were observed. In the genetic-based population pharmacokinetic analyses, none of the SNPs improved model fit. This suggests that pharmacogenetic data need not be included in appropriate first-line treatments with the current artemisinin derivatives and quinolines for uncomplicated malaria in specific populations. However, it cannot be ruled out that our results represent isolated findings, and therefore more studies in different populations, ideally with the same artemisinin-based combination therapies, are needed to evaluate the influence of pharmacogenetic factors on the clearance of antimalarials. PMID:23229480

In silico prediction of multiple-category classification model for cytochrome P450 inhibitors and non-inhibitors using machine-learning method.

PubMed

Lee, J H; Basith, S; Cui, M; Kim, B; Choi, S

2017-10-01

The cytochrome P450 (CYP) enzyme superfamily is involved in phase I metabolism which chemically modifies a variety of substrates via oxidative reactions to make them more water-soluble and easier to eliminate. Inhibition of these enzymes leads to undesirable effects, including toxic drug accumulations and adverse drug-drug interactions. Hence, it is necessary to develop in silico models that can predict the inhibition potential of compounds for different CYP isoforms. This study focused on five major CYP isoforms, including CYP1A2, 2C9, 2C19, 2D6 and 3A4, that are responsible for more than 90% of the metabolism of clinical drugs. The main aim of this study is to develop a multiple-category classification model (MCM) for the major CYP isoforms using a Laplacian-modified naïve Bayesian method. The dataset composed of more than 4500 compounds was collected from the PubChem Bioassay database. VolSurf+ descriptors and FCFP_8 fingerprint were used as input features to build classification models. The results demonstrated that the developed MCM using Laplacian-modified naïve Bayesian method was successful in classifying inhibitors and non-inhibitors for each CYP isoform. Moreover, the accuracy, sensitivity and specificity values for both training and test sets were above 80% and also yielded satisfactory area under the receiver operating characteristic curve and Matthews correlation coefficient values.

Functional characterization of cytochromes P450 2B from the desert woodrat Neotoma lepida

DOE Office of Scientific and Technical Information (OSTI.GOV)

Wilderman, P. Ross, E-mail: pwilderman@ucsd.edu; Jang, Hyun-Hee; Malenke, Jael R.

Mammalian detoxification processes have been the focus of intense research, but little is known about how wild herbivores process plant secondary compounds, many of which have medicinal value or are drugs. cDNA sequences that code for three enzymes of the cytochrome P450 (CYP) 2B subfamily, here termed 2B35, 2B36, and 2B37 have been recently identified from a wild rodent, the desert woodrat (Malenke et al., 2012). Two variant clones of each enzyme were engineered to increase protein solubility and to facilitate purification, as reported for CYP2B enzymes from multiple species. When expressed in Escherichia coli each of the woodrat proteinsmore » gave the characteristic maximum at 450 nm in a reduced carbon monoxide difference spectrum but generally expressed at lower levels than rat CYP2B1. Two enzymes, 2B36 and 2B37, showed dealkylation activity with the model substrates 7-ethoxy-4-(trifluoromethyl)coumarin and 7-benzyloxyresorufin, whereas 2B35 was inactive. Binding of the monoterpene (+)-α-pinene produced a Type I shift in the absorbance spectrum of each enzyme. Mutation of 2B37 at residues 114, 262, or 480, key residues governing ligand interactions with other CYP2B enzymes, did not significantly change expression levels or produce the expected functional changes. In summary, two catalytic and one ligand-binding assay are sufficient to distinguish among CYP2B35, 2B36, and 2B37. Differences in functional profiles between 2B36 and 2B37 are partially explained by changes in substrate recognition site residue 114, but not 480. The results advance our understanding of the mechanisms of detoxification in wild mammalian herbivores and highlight the complexity of this system. - Highlights: • Three CYP2B enzymes from Neotoma lepida were cloned, engineered, and expressed. • A mix of catalytic and binding assays yields unique results for each enzyme. • Mutational analysis indicates CYP{sub 2}B substrate recognition remains to be clarified. • Reported N. lepida gene sequences allow for larger scale analyses of CYP{sub 2}B enzymes.« less

Human Cytochrome P450 Enzyme Modulation by Gymnema sylvestre: A Predictive Safety Evaluation by LC-MS/MS

PubMed Central

Rammohan, Bera; Samit, Karmakar; Chinmoy, Das; Arup, Saha; Amit, Kundu; Ratul, Sarkar; Sanmoy, Karmakar; Dipan, Adhikari; Tuhinadri, Sen

2016-01-01

Background: Traditionally GS is used to treat diabetes mellitus. Drug-herb interaction of GS via cytochrome P450 enzyme system by substrate cocktail method using HLM has not been reported. Objective: To evaluate the in-vitro modulatory effects of GS extracts (aqueous, methanol, ethyl acetate, chloroform and n-hexane) and deacylgymnemic acid (DGA) on human CYP1A2, 2C8, 2C9, 2D6 and 3A4 activities in HLM. Material and Methods: Probe substrate-based LCMS/MS method was established for all CYPs. The metabolite formations were examined after incubation of probe substrates with HLM in the presence or absence of extracts and DGA. The inhibitory effects of GS extracts and DGA were characterized with kinetic parameters IC50 and Ki values. Results: GS extracts showed differential effect on CYP activities in the following order of inhibitory potency: ethyl acetate > Chloroform > methanol > n-hexane > aqueous > DGA. This differential effect was observed against CYP1A2, 2C9 and less on CYP3A4 and 2C8 but all CYPs were unaffected by aqueous extract and DGA. The ethyl acetate and chloroform extract exhibited moderate inhibition towards CYP1A2 and 3A4. The aqueous extract and DGA however showed negligible inhibition towards all five major human CYPs with very high IC50 values (>90μg/ml). Conclusion: The results of our study revealed that phytoconstituents contained in GS, particularly in ethyl acetate and chloroform extracts, were able to inhibit CYP1A2, 3A4 and 2C9. The presence of relatively small, lipophillic yet slightly polar compounds within the GS extracts may be attributed for inhibition activities. These suggest that the herb or its extracts should be examined for potential pharmacokinetic drug interactions in vivo. Abbreviations used: GS: Gymnema sylvestre, GSE: Gymnema sylvestre extract, DGA: deacyl gymnemic acid, CYP: cytochrome P450, DMSO: dimethylsulphoxide, HLM: human liver microsomes, LC-MS/MS: liquid chromatography tandem mass spectroscopy, NADPH: reduced nicotinamide adeninedinucleotide phosphate, NRS: nicotinamide adeninedinucleotide phosphate regenerating system, CHE: chloroform extract, EAE: ethyl acetate extract, NHE- n-hexane extract, AE: aqueous extract, ME: methanol extract PMID:27761064

Simultaneous quantification of the abundance of several cytochrome P450 and uridine 5'-diphospho-glucuronosyltransferase enzymes in human liver microsomes using multiplexed targeted proteomics.

PubMed

Achour, Brahim; Russell, Matthew R; Barber, Jill; Rostami-Hodjegan, Amin

2014-04-01

Cytochrome P450 (P450) and uridine 5'-diphospho-glucuronosyltransferase (UGT) enzymes mediate a major proportion of phase I and phase II metabolism of xenobiotics. In vitro-in vivo extrapolation (IVIVE) of hepatic clearance in conjunction with physiologically-based pharmacokinetics (PBPK) has become common practice in drug development. However, prediction of xenobiotic kinetics in virtual populations requires knowledge of both enzyme abundances and the extent to which these correlate. A multiplexed quantification concatemer (QconCAT) strategy was used in this study to quantify the expression of several P450 and UGT enzymes simultaneously and to establish correlations between various enzyme abundances in 24 individual liver samples (ages 27-66, 14 male). Abundances were comparable to previously reported values, including CYP2C9 (40.0 ± 26.0 pmol mg(-1)), CYP2D6 (11.9 ± 13.2 pmol mg(-1)), CYP3A4 (68.1 ± 52.3 pmol mg(-1)), UGT1A1 (33.6 ± 34.0 pmol mg(-1)), and UGT2B7 (82.9 ± 36.1 pmol mg(-1)), expressed as mean ± S.D. Previous reports of correlations in expression of various P450 (CYP3A4/CYP3A5*1/*3, CYP2C8/CYP2C9, and CYP3A4/CYP2B6) were confirmed. New correlations were demonstrated between UGTs [including UGT1A6/UGT1A9 (r(s) = 0.82, P < 0.0001) and UGT2B4/UGT2B15 (r(s) = 0.71, P < 0.0001)]. Expression of some P450 and UGT enzymes were shown to be correlated [including CYP1A2/UGT2B4 (r(s) = 0.67, P = 0.0002)]. The expression of CYP3A5 in individuals with *1/*3 genotype (n = 11) was higher than those with *3/*3 genotype (n = 10) (P < 0.0001). No significant effect of gender or history of smoking or alcohol use on enzyme expression was observed; however, expression of several enzymes declined with age. The correlation matrix produced for the first time by this study can be used to generate more realistic virtual populations with respect to abundance of various enzymes.

Biochemical responses of Gammarus pulex to malachite green solutions decolorized by Coriolus versicolor as a biosorbent under batch adsorption conditions optimized with response surface methodology.

PubMed

Yildirim, Nuran Cikcikoglu; Tanyol, Mehtap; Yildirim, Numan; Serdar, Osman; Tatar, Sule

2018-07-30

The current study was aimed to investigate the detoxifying and antioxidant enzyme response of Gammarus pulex exposed to malachite green (MG) after decolorization by Coriolus versicolor. Response surface methodology (RSM) was utilized to optimize the decolorization conditions of MG synthetic solutions by C. versicolor. Glutathione (GSH), malondialdehyde (MDA) levels and glutathione peroxidase (GP X ), catalase (CAT), superoxide dismutase (SOD), glutathione S-transferase (GST), cytochrome P450 1A1 (CYP1A1) activities in G. pulex exposed to undecolorized (A1) and decolorized (A2) MG synthetic solution during 24 and 96 h were tested by using ELISA method. SOD and GP X enzyme activity was increased after decolorization (p > 0.05). CAT enzyme activity was increased in A2 group during 24 h (p > 0.05) but decreased during 96 h (p < 0.05). GSH levels were increased in A2 group during 24 and 96 h (p < 0.05). GST, CYP1A1 enzyme activity and MDA levels were decreased after decolorization during 96 h (p < 0.05). In this study, GSH levels, CAT, GST and CYP1A1 activities in G. pulex approved the capability of C. versicolor in MG decolorization, optimized with RSM. Copyright © 2018 Elsevier Inc. All rights reserved.

Nanoscale Electron Transport Measurements of Immobilized Cytochrome P450 Proteins

PubMed Central

Bostick, Christopher D.; Flora, Darcy R.; Gannett, Peter M.; Tracy, Timothy S.; Lederman, David

2015-01-01

Gold nanopillars, functionalized with an organic self-assembled monolayer, can be used to measure the electrical conductance properties of immobilized proteins without aggregation. Measurements of the conductance of nanopillars with cytochrome P450 2C9 (CYP2C9) proteins using conducting probe atomic force microscopy demonstrate that a correlation exists between the energy barrier height between hopping sites and CYP2C9 metabolic activity. Measurements performed as a function of tip force indicate that, when subjected to a large force, the protein is more stable in the presence of a substrate. This agrees with the hypothesis that substrate entry into the active site helps to stabilize the enzyme. The relative distance between hopping sites also increases with increasing force, possibly because protein functional groups responsible for electron transport depend on the structure of the protein. The inhibitor sulfaphenazole, in addition to the previously studied aniline, increased the barrier height for electron transfer and thereby makes CYP2C9 reduction more difficult and inhibits metabolism. This suggests that P450 Type II binders may decrease the ease of electron transport processes in the enzyme, in addition to occupying the active site. PMID:25804257

StAR protein and steroidogenic enzyme expressions in the rat Harderian gland.

PubMed

Falvo, Sara; Chieffi Baccaria, Gabriella; Spaziano, Giuseppe; Rosati, Luigi; Venditti, Massimo; Di Fiore, Maria Maddalena; Santillo, Alessandra

2018-03-01

The Harderian gland (HG) of the rat (Rattus norvegicus) secretes copious amounts of lipids, such as cholesterol. Here we report a study of the expressions of the StAR protein and key steroidogenic enzymes in the HG of male and female rats. The objective of the present investigation was to ascertain (a) whether the rat HG is involved in steroid production starting with cholesterol, and (b) whether the pattern of gene and protein expressions together with the enzymatic activities display sexual dimorphism. The results demonstrate, for the first time, the expression of StAR gene and protein, and Cyp11a1, Hsd3b1, Hsd17b3, Srd5a1, Srd5a2 and Cyp19a1 genes in the rat HG. StAR mRNA and protein expressions were much greater in males than in females. Immunohistochemical analysis demonstrated a non-homogeneous StAR distribution among glandular cells. Hsd17b3 and Cyp19a1 mRNA levels were higher in males than in females, whereas Srd5a1 mRNA levels were higher in females than in males. No significant differences were observed in mRNA levels of Cyp11a1, Hsd3b1 and Srd5a2 between sexes. Furthermore, the in vitro experiments demonstrated a higher 5α-reductase activity in the female as compared to the male HG vice versa a higher P450 aro activity in males as compared to females. These results suggest that the Harderian gland can be classified as a steroidogenic tissue because it synthesizes cholesterol, expresses StAR and steroidogenic enzymes involved in both androgen and estrogen synthesis. The dimorphic expression and activity of the steroidogenic enzymes may suggest sex-specific hormonal effects into the HG physiology. Copyright © 2018 Académie des sciences. Published by Elsevier Masson SAS. All rights reserved.

Interaction of CYP2C19, P2Y12, and GPIIIa Variants Associates With Efficacy of Clopidogrel and Adverse Events on Patients With Ischemic Stroke.

PubMed

Yi, Xingyang; Wang, Yanfen; Lin, Jing; Cheng, Wen; Zhou, Qiang; Wang, Chun

2017-10-01

Clopidogrel is a clinically important oral antiplatelet agent for the treatment or prevention of cerebrovascular disease. However, different individuals have different sensitivities to clopidogrel. This study assessed variants of different genes for association with response to clopidogrel, clinical outcome, and side effects in patients with ischemic stroke (IS). We consecutively enrolled 375 patients with IS after they received clopidogrel therapy, and venous blood samples were subjected to genotyping allelic variants of genes modulating clopidogrel absorption (ATP binding cassette subfamily B1, ABCB1), metabolic activation (cytochrome P450[CYP] 3A and CYP2C19), and biologic activity (platelet membrane receptor [ P2Y12, P2Y1)], and glycoprotein IIIa [ GPIIIa]) and statistically analyzing their interactions with clopidogrel sensitivity (CS) and adverse events, risk of IS recurrence, myocardial infarction, and death during 6 months of follow-up. Adverse events occurred in 37 patients (31 had IS recurrence, 4 died, and 2 had myocardial infarction) during the first 6 months of follow-up. Single locus analysis showed that only the CYP2C19*2(rs4244285) variant was independently associated with CS and risk of adverse events after adjusting covariates. However, there was significant gene-gene interaction among CYP2C19*2(rs4244285), P2Y12(rs16863323), and GPIIIa (rs2317676) analyzed by generalized multifactor dimensionality reduction methods. The rate of adverse events among patients with the 3-loci interaction was 2.82 times the rate among those with no interaction (95% confidence interval: 2.04-8.63). Sensitivity of patients with IS to clopidogrel and clopidogrel-induced adverse clinical events may be multifactorial but is not determined by single gene polymorphisms.

Effects of chronic exposure to tributyltin on tissue-specific cytochrome P450 1 regulation in juvenile common carp.

PubMed

Li, Zhi-Hua; Zhong, Li-Qiao; Mu, Wei-Na; Wu, Yan-Hua

2016-01-01

1. The purpose of this study was to compare tributyltin (TBT)-induced cytochrome P450 1 (CYP450 1) regulation in liver, gills and muscle of juvenile common carp (Cyprinus carpio). 2. Fish were exposed to sublethal concentrations of TBT (75, 0.75 and 7.5 μg/L) for 60 days. CYP450 1A was measured at the enzyme activity level as 7-ethoxyresorufin-O-deethylase (EROD) activity, as well as the mRNA expression of CYP450 1 family genes (CYP1A, CYP1B, CYP1C1 and CYP1C2) in fish tissues. 3. Based on the results, the liver displayed the highest absolute levels of EROD activity, both under nonexposed and exposed conditions. Additional, EROD activities and CYP1A gene levels showed a good correlation in all three organs. According to the mRNA expression of CYP450 1 family genes, it suggested that CYP1A was to accommodate most EROD activity in fish, but other CYP450 forms also involved in this proceeding. 4. Overall, the study revealed both similarities and differences in the concentration-dependent CYP450 1 responses of the three target organs, which could provide useful information to better understand the mechanisms of TBT-induced bio-toxicity.

Stereoselective Inhibition of CYP2C19 and CYP3A4 by Fluoxetine and Its Metabolite: Implications for Risk Assessment of Multiple Time-Dependent Inhibitor Systems

PubMed Central

Lutz, Justin D.; VandenBrink, Brooke M.; Babu, Katipudi N.; Nelson, Wendel L.; Kunze, Kent L.

2013-01-01

Recent guidance on drug-drug interaction (DDI) testing recommends evaluation of circulating metabolites. However, there is little consensus on how to quantitatively predict and/or assess the risk of in vivo DDIs by multiple time-dependent inhibitors (TDIs) including metabolites from in vitro data. Fluoxetine was chosen as the model drug to evaluate the role of TDI metabolites in DDI prediction because it is a TDI of both CYP3A4 and CYP2C19 with a circulating N-dealkylated inhibitory metabolite, norfluoxetine. In pooled human liver microsomes, both enantiomers of fluoxetine and norfluoxetine were TDIs of CYP2C19, (S)-norfluoxetine was the most potent inhibitor with time-dependent inhibition affinity constant (KI) of 7 μM, and apparent maximum time-dependent inhibition rate (kinact,app) of 0.059 min−1. Only (S)-fluoxetine and (R)-norfluoxetine were TDIs of CYP3A4, with (R)-norfluoxetine being the most potent (KI = 8 μM, and kinact,app = 0.011 min−1). Based on in-vitro-to-in-vivo predictions, (S)-norfluoxetine plays the most important role in in vivo CYP2C19 DDIs, whereas (R)-norfluoxetine is most important in CYP3A4 DDIs. Comparison of two multiple TDI prediction models demonstrated significant differences between them in in-vitro-to-in-vitro predictions but not in in-vitro-to-in-vivo predictions. Inclusion of all four inhibitors predicted an in vivo decrease in CYP2C19 (95%) and CYP3A4 (60–62%) activity. The results of this study suggest that adequate worst-case risk assessment for in vivo DDIs by multiple TDI systems can be achieved by incorporating time-dependent inhibition by both parent and metabolite via simple addition of the in vivo time-dependent inhibition rate/cytochrome P450 degradation rate constant (λ/kdeg) values, but quantitative DDI predictions will require a more thorough understanding of TDI mechanisms. PMID:23785064

Cytochrome P450-Mediated Phytoremediation using Transgenic Plants: A Need for Engineered Cytochrome P450 Enzymes

PubMed Central

Kumar, Santosh; Jin, Mengyao; Weemhoff, James L

2013-01-01

There is an increasing demand for versatile and ubiquitous Cytochrome P450 (CYP) biocatalysts for biotechnology, medicine, and bioremediation. In the last decade there has been an increase in realization of the power of CYP biocatalysts for detoxification of soil and water contaminants using transgenic plants. However, the major limitations of mammalian CYP enzymes are that they require CYP reductase (CPR) for their activity, and they show relatively low activity, stability, and expression. On the other hand, bacterial CYP enzymes show limited substrate diversity and usually do not metabolize herbicides and industrial contaminants. Therefore, there has been a considerable interest for biotechnological industries and the scientific community to design CYP enzymes to improve their catalytic efficiency, stability, expression, substrate diversity, and the suitability of P450-CPR fusion enzymes. Engineered CYP enzymes have potential for transgenic plants-mediated phytoremediation of herbicides and environmental contaminants. In this review we discuss: 1) the role of CYP enzymes in phytoremediation using transgenic plants, 2) problems associated with wild-type CYP enzymes in phytoremediation, and 3) examples of engineered CYP enzymes and their potential role in transgenic plant-mediated phytoremediation. PMID:25298920

Preclinical evaluation of the potential for cytochrome P450 inhibition and induction of the selective ALK inhibitor, alectinib.

PubMed

Sekiguchi, Nobuo; Nagao, Shunsuke; Takanashi, Kenji; Kato, Motohiro; Kaneko, Akihisa; Morita, Keiichi; Shindoh, Hidetoshi; Ishigai, Masaki

2017-12-01

1. A novel selective anaplastic lymphoma kinase (ALK) inhibitor, alectinib, has shown remarkable efficacy and safety in patients with ALK-positive non-small-cell lung cancer (NSCLC). The purpose of this study was to evaluate in vitro the potential to inhibit and induce cytochrome P450 (CYP) isoforms for alectinib and its major metabolite M4. 2. Alectinib and M4 did not show the meaningful direct inhibition of six major CYP isoforms (CYP1A2, 2B6, 2C9, 2C19, 2D6 and 3A4) in human liver microsomes (HLM). Alectinib, but not M4, competitively inhibited CYP2C8, by which few marketed drugs are exclusively metabolized, with an inhibition constant of 1.98 μM. 3. Out of the seven CYP isoforms in HLM, alectinib and M4 showed time-dependent inhibition (TDI) of only CYP3A4, which suggests low TDI potential due to low inactivation efficiency. 4. Alectinib exhibited quite smaller induction of mRNA expression of CYP1A2, 2B6 and 3A4 genes in human hepatocytes compared to the respective positive controls, suggesting a low potential of enzyme induction. 5. In summary, the risk of alectinib causing drug-drug interactions with coadministered drugs is expected to be low due to the weak potential of CYP inhibition and induction estimated in the preclinical studies.

The post-menopausal ovary displays a unique pattern of steroidogenic enzyme expression.

PubMed

Havelock, Jon C; Rainey, William E; Bradshaw, Karen D; Carr, Bruce R

2006-01-01

While menopause results in the loss of cyclic steroid production, evidence exists for persistent, albeit reduced, ovarian androgen production. In order to continue to synthesize ovarian androgens, the steroidogenic enzymes necessary for androgen biosynthesis must be present. Few studies have selectively analysed some of the steroidogenic enzymes present in the post-menopausal ovary (PMO), and a comprehensive study of this matter has never been undertaken. RNA and protein were obtained from PMO, pre-menopausal ovarian stroma, corpora lutea (CL), ovarian follicles, placenta, and myometrium. Oligonucleotide microarray analysis was performed to compare the gene expression profiles of PMO with pre-menopausal ovarian stroma. Real-time RT-PCR was performed for LH/HCG receptor (LHCGR), steroidogenic acute regulatory (StAR), cholesterol side-chain cleavage (CYP11A), 3beta-hydroxysteroid dehydrogenase type I (HSD3B1) and type II (HSD3B2, 3betaHSD), 17a-hydroxylase (CYP17), cytochrome b5 (CytB5), and aromatase (CYP19). Western blot analysis was performed for StAR, CYP11A, CYP17,and 3betaHSD. The PMO and pre-menopausal ovarian stroma had a similar pattern of steroidogenic enzyme expression. The PMO had persistent, but reduced, levels of LHCGR and most steroidogenic enzymes. CYP19 and HSD3B2 mRNA were greatly reduced in PMO in comparison with CL (50-fold and 2000-fold less respectively). HSD3B2 was not detectable in PMO by western analysis. This study supports the idea that the PMO retains some steroidogenic capacity. However, based on steroidogenic enzyme expression, the PMO has a unique pattern of steroidogenic enzyme expression that favors Delta5 steroid formation over Delta4 steroid formation.

Overlapping but distinct specificities of anti-liver-kidney microsome antibodies in autoimmune hepatitis type II and hepatitis C revealed by recombinant native CYP2D6 and novel peptide epitopes

PubMed Central

Klein, R; Zanger, U M; Berg, T; Hopf, U; Berg, P A

1999-01-01

Anti-liver-kidney microsome antibodies (anti-LKM) occur in autoimmune hepatitis (AIH) type II and in a subset of patients with hepatitis C. Anti-LKM1 in AIH are directed against cytochrome P4502D6 (CYP2D6), but conflicting data exist concerning the specificity of anti-LKM in hepatitis C. The aim of this study was to evaluate binding specificities of anti-LKM antibodies in both diseases using novel test antigens as well as their inhibitory capacity on CYP2D6 enzyme activity. Sera from 22 patients with AIH type II and 17 patients with hepatitis C being anti-LKM-positive in the immunofluorescence test were investigated for binding to native recombinant CYP2D6 and liver microsomes by ELISA and immunoblotting, and to synthetic peptides covering the region 254–339 (254–273, 257–269, 270–294, 291–310, 307–324, 321–339, 373–389) as well as the novel peptide 196–218 by ELISA. Furthermore, all sera were tested for inhibition of CYP2D6-dependent bufuralol 1′-hydroxylase activity. Twenty of the 22 AIH type II sera (91%) and nine of the 17 hepatitis C sera (53%) were positive for CYP2D6 by ELISA and/or immunoblotting. The previously described major peptide epitope comprising CYP2D6 amino acids 257–269 was recognized by 16 of the 22 AIH sera but by only one hepatitis C serum. A further epitope, 196–218, could be defined for the first time as another immunodominant epitope for AIH because it was recognized by 15 of the 22 AIH (68%) but only three of the 17 hepatitis C sera (18%). With the exception of the peptide 254–273, the other peptides showed no significant reactivity. Analysing the inhibitory properties of anti-LKM antibodies it emerged that 95% of AIH sera and 88% of hepatitis C sera inhibited enzyme function. These data indicate that anti-LKM antibodies in AIH and hepatitis C react with CYP2D6, as shown by their inhibitory activity, and that besides the known epitope 257–269 a further immunodominant epitope exists on CYP2D6 which is recognized by sera from patients with AIH II but hardly by sera from patients with hepatitis C. PMID:10540193

Effect of atrazine and chlorpyrifos exposure on cytochrome P450 contents and enzyme activities in common carp gills.

PubMed

Fu, Yao; Li, Ming; Liu, Ci; Qu, Jian-Ping; Zhu, Wen-Jun; Xing, Hou-Juan; Xu, Shi-Wen; Li, Shu

2013-08-01

Chlorpyrifos (CPF) and atrazine (ATR) are the most widely used organophosphate insecticides and triazine herbicides, respectively, worldwide. This study aimed at investigating the effects of ATR, CPF and mixture on common carp gills following 40-d exposure and 40-d recovery experiments. Cytochrome P450 content, activities of aminopyrine N-demethylase (APND) and erythromycin N-demethylase (ERND) and the mRNA levels of the CYP1 family (CYP1A, CYP1B, and CYP1C) were determined. In total, 220 common carps were divided into eleven groups, and each group was treated with a specific concentration of ATR (4.28, 42.8 and 428 μg/L), CPF (1.16, 11.6 and 116 μg/L) or ATR-CPF mixture (1.13, 11.3 and 113 μg/L). The results showed that P450 content and activities of APND and ERND in fish exposed to ATR and mixture were significantly higher than those in the control group. After the 40-d recovery treatment (i.e., depuration), the P450 content and the activities of APND and ERND in fish decreased to the background levels. A similar tendency was also found in the mRNA levels of the CYP1 family (CYP1A, CYP1B, and CYP1C) in common carp gills. The CPF-treated fish showed no significant difference from the control groups, except for a significant CYP1C induction. These results indicated that CYP enzyme levels are induced by ATR but were only slightly affected by CPF in common carp gills. In addition, the ATR and CPF exposure showed an antagonistic effect on P450 enzymes in common carp gills. Copyright © 2013 Elsevier Inc. All rights reserved.

Subcellular localization of rat CYP2E1 impacts metabolic efficiency toward common substrates.

PubMed

Hartman, Jessica H; Martin, H Cass; Caro, Andres A; Pearce, Amy R; Miller, Grover P

2015-12-02

Cytochrome P450 2E1 (CYP2E1) detoxifies or bioactivates many low molecular-weight compounds. Most knowledge about CYP2E1 activity relies on studies of the enzyme localized to endoplasmic reticulum (erCYP2E1); however, CYP2E1 undergoes transport to mitochondria (mtCYP2E1) and becomes metabolically active. We report the first comparison of in vitro steady-state kinetic profiles for erCYP2E1 and mtCYP2E1 oxidation of probe substrate 4-nitrophenol and pollutants styrene and aniline using subcellular fractions from rat liver. For all substrates, metabolic efficiency changed with substrate concentration for erCYP2E1 reflected in non-hyperbolic kinetic profiles but not for mtCYP2E1. Hyperbolic kinetic profiles for the mitochondrial enzyme were consistent with Michaelis-Menten mechanism in which metabolic efficiency was constant. By contrast, erCYP2E1 metabolism of 4-nitrophenol led to a loss of enzyme efficiency at high substrate concentrations when substrate inhibited the reaction. Similarly, aniline metabolism by erCYP2E1 demonstrated negative cooperativity as metabolic efficiency decreased with increasing substrate concentration. The opposite was observed for erCYP2E1 oxidation of styrene; the sigmoidal kinetic profile indicated increased efficiency at higher substrate concentrations. These mechanisms and CYP2E1 levels in mitochondria and endoplasmic reticulum were used to estimate the impact of CYP2E1 subcellular localization on metabolic flux of pollutants. Those models showed that erCYP2E1 mainly carries out aniline metabolism at all aniline concentrations. Conversely, mtCYP2E1 dominates styrene oxidation at low styrene concentrations and erCYP2E1 at higher concentrations. Taken together, subcellular localization of CYP2E1 results in distinctly different enzyme activities that could impact overall metabolic clearance and/or activation of substrates and thus impact the interpretation and prediction of toxicological outcomes. Copyright © 2015 Elsevier Ireland Ltd. All rights reserved.

Genetic polymorphisms of genes coding to alcohol-metabolizing enzymes in western Mexicans: association of CYP2E1*c2/CYP2E1*5B allele with cirrhosis and liver function.

PubMed

García-Bañuelos, Jesús; Panduro, Arturo; Gordillo-Bastidas, Daniela; Gordillo-Bastidas, Elizabeth; Muñoz-Valle, José Francisco; Gurrola-Díaz, Carmen M; Sánchez-Enríquez, Sergio; Ruiz-Madrigal, Bertha; Bastidas-Ramírez, Blanca Estela

2012-03-01

Alcoholic cirrhosis constitutes a major public health problem in the world where ADH1B, ALDH2, and CYP2E1 polymorphisms could be playing an important role. We determined ADH1B*2, ALDH2*2, and CYP2E1*c2 allele frequencies in healthy control individuals (C) and patients with alcoholic cirrhosis (AC) from western Mexico. Ninety C and 41 patients with AC were studied. Genotype and allele frequency were determined through polymerase chain reaction-restriction fragment length polymorphisms. Polymorphic allele distribution in AC was 1.6%ADH1B*2, 0.0%ALDH2*2, and 19.5%CYP2E1*c2; in C: 6.1%ADH1B*2, 0%ALDH2*2, and 10.6%CYP2E1*c2. CYP2E1*c2 polymorphic allele and c1/c2 genotype frequency were significantly higher (p < 0.05 and p < 0.01, respectively) in patients with AC when compared to C. Patients with AC, carrying the CYP2E1*c2 allele, exhibited more decompensated liver functioning evaluated by total bilirubin and prothrombin time, than c1 allele carrying patients (p < 0.05). Cirrhosis severity, assessed by Child's Pugh score and mortality, was higher in patients carrying the c2 allele, although not statistically significant. In this study, CYP2E1*c2 allele was associated with susceptibility to AC; meanwhile, ADH1B*2 and ALDH2*2 alleles were not. CYP2E1*c2 allele was associated with AC severity, which could probably be attributed to the oxidative stress promoted by this polymorphic form. Further studies to clearly establish CYP2E1*c2 clinical relevance in the development of alcohol-induced liver damage and its usefulness as a probable prognostic marker, should be performed. Also, increasing the number of patients and including a control group conformed by alcoholic patients free of liver damage may render more conclusive results. These findings contribute to the understanding of the influence of gene variations in AC development among populations, alcohol metabolism, and pharmacogenetics. Copyright © 2011 by the Research Society on Alcoholism.

Metronidazole reduces the expression of cytochrome P450 enzymes in HepaRG cells and cryopreserved human hepatocytes.

PubMed

Kudo, Toshiyuki; Endo, Yumiko; Taguchi, Rina; Yatsu, Masami; Ito, Kiyomi

2015-05-01

1. Blood levels of S-warfarin have been reported to be increased by concomitant administration of metronidazole (MTZ), an antiprotozoal imidazole derivative. 2. To elucidate the mechanism of this interaction and to identify other possible drug-drug interactions, we conducted an in vitro study with the human hepatoma HepaRG cells and cryopreserved human hepatocytes on the ability of MTZ to reduce the expression of cytochrome P450 (CYP) as well as nuclear receptors that regulate the expression of these enzymes. 3. HepaRG cells and cryopreserved human hepatocytes were treated with MTZ (20 to 500 µM) and were then analyzed by real-time RT-PCR to determine mRNA levels of drug-metabolizing enzymes and nuclear receptors. 4. In both cells, the expressions of CYP2C8, CYP2C9, CYP3A4 and constitutive androstane receptor (CAR) were decreased by MTZ treatment. Particularly, in HepaRG cells, their mRNA levels were decreased by MTZ treatment in a concentration-dependent manner. 5. Our findings suggest that the interaction between MTZ and S-warfarin may be due to the MTZ-induced down-regulation of CYP2C9, the primary enzyme responsible for S-warfarin hydroxylation, and CAR, which regulates CYP2C9 expression. We also found that MTZ use may alter the disposition of drugs metabolized by the CYP isozymes investigated.

Effect of the CYP2C19 genotype on the pharmacokinetics of icotinib in healthy male volunteers.

PubMed

Ruan, Can-Jun; Liu, Dong-Yang; Jiang, Ji; Hu, Pei

2012-12-01

Icotinib hydrochloride {4-[(3-ethynylphenyl)amino]-6,7-benzo-12-crown-4-quinazoline hydrochloride}, a novel epidermal growth factor receptor (EGFR)-tyrosine kinase inhibitor (TKI), was designed for the treatment of non-small cell lung cancer (NSCLC). In the present study, we investigated the influence of the CYP2C19*2 and CYP2C19*3 alleles on the pharmacokinetics of icotinib in healthy Chinese volunteers. In a single-dose pharmacokinetic study, 12 healthy Chinese volunteers received an oral dose of 600 mg of icotinib. Plasma was sampled for up to 72 h post-dose, followed by quantification of icotinib by liquid chromatography-mass spectrometry/mass spectrometry (LC-MS-MS). Five subjects genotyped as homozygous extensive metabolizers (CYP2C19*1/*1), 6 subjects genotyped as heterozygous extensive metabolizers (CYP2C19*1/*2 or CYP2C19*1/*3), and 1 subject genotyped as a poor metabolizer (CYP2C19*2/*3) and was withdrawn from the research because of urticaria. The mean icotinib AUC(0-∞) and C(max) (14.56 ±5.31 h mg/L and 2.32 ± 0.49 μg/mL) in homozygous EMs was 1.56 and 1.41-fold lower than that in heterozygous EMs (22.7 ± 6.11 and 3.28 ± 0.48, P = 0.046 and 0.047). The mean CL/F (44.18 ± 12.17 L/h) in homozygous EMs was 1.55-fold higher than that in heterozygous EMs (28.42 ± 9.23 L/h, P = 0.013). The data showed that the pharmacokinetics of icotinib differ significantly between homozygous EMs and heterozygous EMs in CYP2C19.

CYP2E1 overexpression inhibits microsomal Ca2+-ATPase activity in HepG2 cells.

PubMed

Caro, Andres A; Evans, Kerry L; Cederbaum, Arthur I

2009-01-31

Cytochrome P450 2E1 (CYP2E1) is a microsomal enzyme that generates reactive oxygen species during its catalytic cycle. We previously found an important role for calcium in CYP2E1-potentiated injury in HepG2 cells. The possibility that CYP2E1 may oxidatively damage and inactivate the microsomal Ca2+-ATPase in intact liver cells was evaluated, in order to explain why calcium is elevated during CYP2E1 toxicity. Microsomes were isolated by differential centrifugation from two liver cell line: E47 cells (HepG2 cells transfected with the pCI neo expression vector containing the human CYP2E1 cDNA, which overexpress active microsomal CYP2E1), and control C34 cells (HepG2 cells transfected with the pCI neo expression vector alone, which do not express significantly any cytochrome P450). The Ca2+-dependent ATPase activity was determined by measuring the accumulation of inorganic phosphate from ATP hydrolysis. CYP2E1 overexpression produced a 45% decrease in Ca2+-dependent ATPase activity (8.6 nmol Pi/min/mg protein in C34 microsomes versus 4.7 nmol Pi/min/mg protein in microsomes). Saturation curves with Ca2+ or ATP showed that CYP2E1 overexpression produced a decrease in Vmax but did not affect the Km for either Ca2+ or ATP. The decrease in activity was not associated with a decrease in SERCA protein levels. The ATP-dependent microsomal calcium uptake was evaluated by fluorimetry using fluo-3 as the fluorogenic probe. Calcium uptake rate in E47 microsomes was 28% lower than in C34 microsomes. Treatment of E47 cells with 2mM N-acetylcysteine prevented the decrease in microsomal Ca2+-ATPase found in E47 cells. These results suggest that CYP2E1 overexpression produces a decrease in microsomal Ca2+-ATPase activity in HepG2 cells mediated by reactive oxygen species. This may contribute to elevated cytosolic calcium and to CYP2E1-potentiated injury.

Pyrethroid Activity-Based Probes for Profiling Cytochrome P450 Activities Associated with Insecticide Interactions

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ismail, Hanafy M.; O'Neill, Paul M.; Hong, David

2014-01-18

Pyrethroid insecticides are used to control a diverse spectrum of diseases spread by arthropods. We have developed a suite of pyrethroid mimetic activity based probes (PyABPs) to selectively label and identify P450s associated with pyrethroid metabolism. The probes were screened against pyrethroid metabolizing and non-metabolizing mosquito P450s, as well as rodent microsomes to measure labeling specificity, plus CPR and b5 knockout mouse livers to validate P450 activation and establish the role for b5 in probe activation. Using a deltamethrin mimetic PyABP we were able to profile active enzymes in rat liver microsomes and identify pyrethroid metabolizing enzymes in the targetmore » tissue. The most reactive enzyme was a P450, CYP2C11, which is known to metabolize deltamethrin. Furthermore, several other pyrethroid metabolizers were identified (CYPs 2C6, 3A4, 2C13 and 2D1) along with related detoxification enzymes, notably UDP-g’s 2B1 - 5, suggesting a network of associated pyrethroid metabolizing enzymes, or ‘pyrethrome’. Considering the central role that P450s play in metabolizing insecticides, we anticipate that PyABPs will aid the identification and profiling of P450s associated with insecticide pharmacology in a wide range of species, improving understanding of P450-insecticide interactions and aiding the development of new tools for disease control.« less

Jumpstarting the cytochrome P450 catalytic cycle with a hydrated electron.

PubMed

Erdogan, Huriye; Vandemeulebroucke, An; Nauser, Thomas; Bounds, Patricia L; Koppenol, Willem H

2017-12-29

Cytochrome P450cam (CYP101Fe 3+ ) regioselectively hydroxylates camphor. Possible hydroxylating intermediates in the catalytic cycle of this well-characterized enzyme have been proposed on the basis of experiments carried out at very low temperatures and shunt reactions, but their presence has not yet been validated at temperatures above 0 °C during a normal catalytic cycle. Here, we demonstrate that it is possible to mimic the natural catalytic cycle of CYP101Fe 3+ by using pulse radiolysis to rapidly supply the second electron of the catalytic cycle to camphor-bound CYP101[FeO 2 ] 2+ Judging by the appearance of an absorbance maximum at 440 nm, we conclude that CYP101[FeOOH] 2+ (compound 0) accumulates within 5 μs and decays rapidly to CYP101Fe 3+ , with a k 440 nm of 9.6 × 10 4 s -1 All processes are complete within 40 μs at 4 °C. Importantly, no transient absorbance bands could be assigned to CYP101[FeO 2+ por •+ ] (compound 1) or CYP101[FeO 2+ ] (compound 2). However, indirect evidence for the involvement of compound 1 was obtained from the kinetics of formation and decay of a tyrosyl radical. 5-Hydroxycamphor was formed quantitatively, and the catalytic activity of the enzyme was not impaired by exposure to radiation during the pulse radiolysis experiment. The rapid decay of compound 0 enabled calculation of the limits for the Gibbs activation energies for the conversions of compound 0 → compound 1 → compound 2 → CYP101Fe 3+ , yielding a Δ G ‡ of 45, 39, and 39 kJ/mol, respectively. At 37 °C, the steps from compound 0 to the iron(III) state would take only 4 μs. Our kinetics studies at 4 °C complement the canonical mechanism by adding the dimension of time. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Identification of human drug-metabolizing enzymes involved in the metabolism of SNI-2011.

PubMed

Washio, T; Arisawa, H; Kohsaka, K; Yasuda, H

2001-11-01

In vitro studies were conducted to identify human drug-metabolizing enzymes involved in the metabolism of SNI-2011 ((+/-)-cis-2-methylspiro [1,3-oxathiolane-5,3'-quinuclidine] monohydrochloride hemihydrate, cevimeline hydrochloride hydrate). When 14C-SNI-2011 was incubated with human liver microsomes, SNI-2011 trans-sulfoxide and cis-sulfoxide were detected as major metabolites. These oxidations required NADPH, and were markedly inhibited by SKF-525A, indicating that cytochrome P450 (CYP) was involved. In a chemical inhibition study, metabolism of SNI-2011 in liver microsomes was inhibited (35-65%) by CYP3A4 inhibitors (ketoconazole and troleandomycin) and CYP2D6 inhibitors (quinidine and chlorpromazine). Furthermore, using microsomes containing cDNA-expressed CYPs, it was found that high rates of sulfoxidation activities were observed with CYP2D6 and CYP3A4. On the other hand, when 14C-SNI-2011 was incubated with human kidney microsomes, SNI-2011 N-oxide was identified as a major metabolite. This N-oxidation required NADPH, and was completely inhibited by thiourea, indicating that flavin-containing monooxygenase (FMO) was involved. In addition, microsomes containing cDNA-expressed FMO1, a major isoform in human kidney, mainly catalyzed N-oxidation of SNI-2011, but microsomes containing FMO3, a major isoform in adult human liver, did not. These results suggest that SNI-2011 is mainly catalyzed to sulfoxides and N-oxide by CYP2D6/3A4 in liver and FMOI in kidney, respectively.

Clopidogrel and proton pump inhibitor (PPI) interaction: separate intake and a non-omeprazole PPI the solution?

PubMed

Kenngott, S; Olze, R; Kollmer, M; Bottheim, H; Laner, A; Holinski-Feder, E; Gross, M

2010-05-18

Dual therapy with aspirin and clopidogrel increases the risk of gastrointestinal bleeding. Therefore, co-therapy with a proton pump inhibitor (PPI) is recommended by most guidelines. However, there are warnings against combining PPIs with clopidogrel because of their interactions with cytochrome P450 isoenzyme 2C19 (CYP2C19). The effects of the combined or separate intake of 20 mg of omeprazole and 75 mg of clopidogrel on the clopidogrel-induced inhibition of platelet aggregation were measured in four healthy subjects whose CYP2C19 exon sequences were determined. The effects of co-therapy with 10 mg of rabeprazole were also examined. Two subjects showed the wild-type CYP2C19 sequence. The concurrent intake of omeprazole had no effect on clopidogrel-induced platelet inhibition in these subjects. Two subjects were heterozygous for the *2 allele, with predicted reduced CYP2C19 activity. One of them was a clopidogrel non-responder. In the second heterozygous subject, omeprazole co-therapy reduced the clopidogrel anti-platelet effect when taken simultaneously or separately. However, the simultaneous intake of rabeprazole did not reduce the clopidogrel effect. The clopidogrel-PPI interaction does not seem to be a PPI class effect. Rabeprazole did not affect the clopidogrel effect in a subject with a clear omeprazole-clopidogrel interaction. The separate intake of PPI and clopidogrel may not be sufficient to prevent their interaction.

Metabolic Pathway of Icotinib In Vitro: The Differential Roles of CYP3A4, CYP3A5, and CYP1A2 on Potential Pharmacokinetic Drug-Drug Interaction.

PubMed

Zhang, TianHong; Zhang, KeRong; Ma, Li; Li, Zheng; Wang, Juan; Zhang, YunXia; Lu, Chuang; Zhu, Mingshe; Zhuang, XiaoMei

2018-04-01

Icotinib is the first self-developed small molecule drug in China for targeted therapy of non-small cell lung cancer. To date, systematic studies on the pharmacokinetic drug-drug interaction of icotinib were limited. By identifying metabolite generated in human liver microsomes and revealing the contributions of major cytochromes P450 (CYPs) in the formation of major metabolites, the aim of the present work was to understand the mechanisms underlying pharmacokinetic and pharmacological variability in clinic. A liquid chromatography/UV/high-resolution mass spectrometer method was developed to characterize the icotinib metabolites. The formation of 6 major metabolites was studied in recombinant CYP isozymes and human liver microsomes with specific inhibitors to identify the CYPs responsible for icotinib metabolism. The metabolic pathways observed in vitro are consistent with those observed in human. Results demonstrated that the metabolites are predominantly catalyzed by CYP3A4 (77%∼87%), with a moderate contribution from CYP3A5 (5%∼15%) and CYP1A2 (3.7%∼7.5%). The contribution of CYP2C8, 2C9, 2C19, and 2D6 is insignificant. Based on our observations, to minimize drug-drug interaction risk in clinic, coprescription of icotinib with strong CYP3A inhibitors or inducers must be weighed. CYP1A2, a highly inducible enzyme in the smoking population, may also represent a determinant of pharmacokinetic and pharmacological variability of icotinib, especially in lung cancer patients with smoking history. Copyright © 2018 American Pharmacists Association®. Published by Elsevier Inc. All rights reserved.

Effects of CYP3A5, CYP2C19, and CYP2B6 on the clinical efficacy and adverse outcomes of sibutramine therapy: a crucial role for the CYP2B6*6 allele.

PubMed

Hwang, In Cheol; Park, Ji Young; Ahn, Hong Yup; Kim, Kyoung Kon; Suh, Heuy Sun; Ko, Ki Dong; Kim, Kyoung-Ah

2014-01-20

Various cytochrome P450 isoforms modulate sibutramine activity and influence sibutramine plasma levels and pharmacokinetics. However, there are no available data to demonstrate the association of these polymorphisms with the clinical outcomes of sibutramine administration. This study was a sub-investigation of a 12-week, double-blind, placebo-controlled trial examining the additive effect of orlistat on sibutramine. The final analysis was restricted to 101 women who had fulfilled the protocol. We evaluated the effects of genetic polymorphisms of CYP3A5, CYP2C19 and CYP2B6 on the % weight loss and the occurrence of adverse events. The change of pulse rate from baseline value was affected by both CYP2B6 and CYP3A5 genetic polymorphisms (P<.01 for CYP3A5 and P=.01 for CYP2B6). Both CYP2B6 and CYP3A5 showed gene-gene interactions (P<.01). After adjusting for significant variables in the backward stepwise regression model, the change of pulse rate and time-dependent weight reduction were significant only among the CYP2B6 genotypes (P=.027 and P<.01, respectively). The CYP2B6*6 allele influences the extent of weight reduction and pulse rate changes in patients undergoing sibutramine treatment. Copyright © 2013 Elsevier B.V. All rights reserved.

Glucocorticoid receptor contributes to the altered expression of hepatic cytochrome P450 upon cigarette smoking.

PubMed

Li, Xue; Yan, Zhongfang; Wu, Qi; Sun, Xin; Li, Fan; Zhang, Subei; Li, Kuan; Li, Li; Wu, Junping; Xu, Long; Feng, Jing; Ning, Wen; Liu, Zhixue; Chen, Huaiyong

2016-12-01

Cigarette smoking has been shown to cause pathological alterations in the liver. However, how hepatic metabolism is altered during cigarette smoking‑induced inflammation remains to be fully elucidated. In the present study, a rat model of smoking was established to examine the effects of cigarette smoking on inflammation, autophagy activity, and the expression of nuclear receptor and CYP in the liver. Elevated expression of interleukin 1β and activation of autophagy in the liver were observed upon smoking exposure in rats. Cigarette smoking induced a significant reduction in the mRNA expression levels of cytochromes, including cytochrome P450 (Cyp)1A2, Cyp2D4 and Cyp3A2. Accordingly, a decrease was also observed in glucocorticoid receptor (GR), a regulator of the expression of Cyp. Activation of the GR signal in human hepatic LO2 cells did not affect autophagic genes, however, it led to the upregulation of hCYP1A2, hCYP2C19 and hCYP3A4, and the downregulation of hCYP2C9. The GR antagonist, RU486, eliminated this effect, suggesting the importance of GR in liver metabolism upon cigarette smoking.

Dual Function of the Cytochrome P450 CYP76 Family from Arabidopsis thaliana in the Metabolism of Monoterpenols and Phenylurea Herbicides1[W][OPEN

PubMed Central

Höfer, René; Boachon, Benoît; Renault, Hugues; Gavira, Carole; Miesch, Laurence; Iglesias, Juliana; Ginglinger, Jean-François; Allouche, Lionel; Miesch, Michel; Grec, Sebastien; Larbat, Romain; Werck-Reichhart, Danièle

2014-01-01

Comparative genomics analysis unravels lineage-specific bursts of gene duplications related to the emergence of specialized pathways. The CYP76C subfamily of cytochrome P450 enzymes is specific to Brassicaceae. Two of its members were recently associated with monoterpenol metabolism. This prompted us to investigate the CYP76C subfamily genetic and functional diversification. Our study revealed high rates of CYP76C gene duplication and loss in Brassicaceae, suggesting the association of the CYP76C subfamily with species-specific adaptive functions. Gene differential expression and enzyme functional specialization in Arabidopsis thaliana, including metabolism of different monoterpenols and formation of different products, support this hypothesis. In addition to linalool metabolism, CYP76C1, CYP76C2, and CYP76C4 metabolized herbicides belonging to the class of phenylurea. Their ectopic expression in the whole plant conferred herbicide tolerance. CYP76Cs from A. thaliana. thus provide a first example of promiscuous cytochrome P450 enzymes endowing effective metabolism of both natural and xenobiotic compounds. Our data also suggest that the CYP76C gene family provides a suitable genetic background for a quick evolution of herbicide resistance. PMID:25082892

Effects of Vernonia cinerea Compounds on Drug-metabolizing Cytochrome P450s in Human Liver Microsomes.

PubMed

Pouyfung, Phisit; Sarapusit, Songklod; Rongnoparut, Pornpimol

2017-12-01

Vernonia cinerea has been widely used in traditional medicines for various diseases and shown to aid in smoking abstinence and has anticancer properties. V. cinerea bioactive compounds, including flavonoids and hirsutinolide-type sesquiterpene lactones, have shown an inhibition effect on the nicotine-metabolizing cytochrome P450 2A6 (CYP2A6) enzyme and hirsutinolides reported suppressing cancer growth. In this study, V. cinerea ethanol extract and its bioactive compounds, including four flavonoids and four hirsutinolides, were investigated for an inhibitory effect on human liver microsomal CYPs 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4 using cocktail inhibition assays combined with LC-MS/MS analysis. Among tested flavonoids, chrysoeriol was more potent in inhibition on CYP2A6 and CYP1A2 than other liver CYPs, with better binding efficiency toward CYP2A6 than CYP1A2 (K i values in competitive mode of 1.93 ± 0.05 versus 3.39 ± 0.21 μM, respectively). Hirsutinolides were prominent inhibitors of CYP2A6 and CYP2D6, with IC 50 values of 12-23 and 15-41 μM, respectively. These hirsutinolides demonstrated time-dependent inhibition, an indication of mechanism-based inactivation, toward CYP2A6. Quantitative prediction of microsomal metabolism of these flavonoids and hirsutinolides, including half-lives and hepatic clearance rate, was examined. These findings may have implications for further in vivo studies of V. cinerea. Copyright © 2017 John Wiley & Sons, Ltd. Copyright © 2017 John Wiley & Sons, Ltd.

The Implication of the Polymorphisms of COX-1, UGT1A6, and CYP2C9 among Cardiovascular Disease (CVD) Patients Treated with Aspirin.

PubMed

Jalil, Nur Jalinna Abdul; Bannur, Zakaria; Derahman, A; Maskon, O; Darinah, Noor; Hamidi, Hamat; Gunasekaran, Osama Ali; Rafizi, Mohd; Azreen, Nur Izatul; Kek, Teh Lay; Salleh, Mohd Zaki

2015-01-01

  Enzymes potentially responsible for the pharmacokinetic variations of aspirin include cyclooxygenase-1 (COX-1), UDP-glucuronosyltransferase (UGT1A6) and P450 (CYP) (CYP2C9). We therefore aimed to determine the types and frequencies of variants of COX-1 (A-842G), UGT1A6 (UGT1A6*2; A541G and UGT1A6*3; A522C) and CYP2C9 (CYP2C9*3; A1075C) in the three major ethnic groups in Malaysia. In addition, the role of these polymorphisms on aspirin-induced gastritis among the patients was investigated. A total of 165 patients with cardiovascular disease who were treated with 75-150 mg daily dose of aspirin and 300 healthy volunteers were recruited. DNA was extracted from the blood samples and genotyped for COX-1 (A-842G), UGT1A6 (UGT1A6*2 and UGT1A6*3) and CYP2C9 (CYP2C9*3; A1075C) using allele specific polymerase chain reaction (AS-PCR). Variants UGT1A6*2,*3 and CYP2C9*3 were detected in relatively high percentage of 22.83%, 30.0% and 6.50%, respectively; while COX-1 (A-842G) was absent. The genotype frequencies for UGT1A6*2 and *3 were significantly different between Indians and Malays or Chinese. The level of bilirubin among patients with different genotypes of UGT1A6 was significantly different (p-value < 0.05). In addition, CYP2C9*3 was found to be associated with gastritis with an odd ratio of 6.8 (95 % Cl OR: 1.39 - 33.19; P = 0.033). Screening of patients with defective genetic variants of UGT1A6 and CYP2C9*3 helps in identifying patients at risk of aspirin induced gastritis. However, a randomised clinical study of bigger sample size would be needed before it is translated to clinical use.

Interactions of the hepatitis C virus protease inhibitor faldaprevir with cytochrome P450 enzymes: in vitro and in vivo correlation.

PubMed

Sabo, John P; Kort, Jens; Ballow, Charles; Kashuba, Angela D M; Haschke, Manuel; Battegay, Manuel; Girlich, Birgit; Ting, Naitee; Lang, Benjamin; Zhang, Wei; Cooper, Curtis; O'Brien, Drané; Seibert, Eleanore; Chan, Tom S; Tweedie, Donald; Li, Yongmei

2015-04-01

The potential inhibition of the major human cytochrome P450 (CYP) enzymes by faldaprevir was evaluated both in vitro and in clinical studies (healthy volunteers and hepatitis C virus [HCV] genotype 1-infected patients). In vitro studies indicated that faldaprevir inhibited CYP2B6, CYP2C9, and CYP3A, and was a weak-to-moderate inactivator of CYP3A4. Faldaprevir 240 mg twice daily in healthy volunteers demonstrated moderate inhibition of hepatic and intestinal CYP3A (oral midazolam: 2.96-fold increase in AUC(0-24 h)), weak inhibition of hepatic CYP3A (intravenous midazolam: 1.56-fold increase in AUC(0-24 h)), weak inhibition of CYP2C9 ([S]-warfarin: 1.29-fold increase in AUC(0-120 h)), and had no relevant effects on CYP1A2, CYP2B6, or CYP2D6. Faldaprevir 120 mg once daily in HCV-infected patients demonstrated weak inhibition of hepatic and intestinal CYP3A (oral midazolam: 1.52-fold increase in AUC(0-∞)), and had no relevant effects on CYP2C9 or CYP1A2. In vitro drug-drug interaction predictions based on inhibitor concentration ([I])/inhibition constant (Ki) ratios tended to overestimate clinical effects and a net-effect model provided a more accurate approach. These studies suggest that faldaprevir shows a dose-dependent inhibition of CYP3A and CYP2C9, and does not induce CYP isoforms. © 2015, The American College of Clinical Pharmacology.

Tafenoquine and NPC-1161B require CYP 2D metabolism for anti-malarial activity: implications for the 8-aminoquinoline class of anti-malarial compounds

PubMed Central

2014-01-01

Background Tafenoquine (TQ) is an 8-aminoquinoline (8AQ) that has been tested in several Phase II and Phase III clinical studies and is currently in late stage development as an anti-malarial prophylactic agent. NPC-1161B is a promising 8AQ in late preclinical development. It has recently been reported that the 8AQ drug primaquine requires metabolic activation by CYP 2D6 for efficacy in humans and in mice, highlighting the importance of pharmacogenomics in the target population when administering primaquine. A logical follow-up study was to determine whether CYP 2D activation is required for other compounds in the 8AQ structural class. Methods In the present study, the anti-malarial activities of NPC-1161B and TQ were assessed against luciferase expressing Plasmodium berghei in CYP 2D knock-out mice in comparison with normal C57BL/6 mice (WT) and with humanized/CYP 2D6 knock-in mice by monitoring luminescence with an in vivo imaging system. These experiments were designed to determine the direct effects of CYP 2D metabolic activation on the anti-malarial efficacy of NPC-1161B and TQ. Results NPC-1161B and TQ exhibited no anti-malarial activity in CYP 2D knock-out mice when dosed at their ED100 values (1 mg/kg and 3 mg/kg, respectively) established in WT mice. TQ anti-malarial activity was partially restored in humanized/CYP 2D6 knock-in mice when tested at two times its ED100. Conclusions The results reported here strongly suggest that metabolism of NPC-1161B and TQ by the CYP 2D enzyme class is essential for their anti-malarial activity. Furthermore, these results may provide a possible explanation for therapeutic failures for patients who do not respond to 8AQ treatment for relapsing malaria. Because CYP 2D6 is highly polymorphic, variable expression of this enzyme in humans represents a significant pharmacogenomic liability for 8AQs which require CYP 2D metabolic activation for efficacy, particularly for large-scale prophylaxis and eradication campaigns. PMID:24386891

Tafenoquine and NPC-1161B require CYP 2D metabolism for anti-malarial activity: implications for the 8-aminoquinoline class of anti-malarial compounds.

PubMed

Marcsisin, Sean R; Sousa, Jason C; Reichard, Gregory A; Caridha, Diana; Zeng, Qiang; Roncal, Norma; McNulty, Ronan; Careagabarja, Julio; Sciotti, Richard J; Bennett, Jason W; Zottig, Victor E; Deye, Gregory; Li, Qigui; Read, Lisa; Hickman, Mark; Dhammika Nanayakkara, N P; Walker, Larry A; Smith, Bryan; Melendez, Victor; Pybus, Brandon S

2014-01-03

Tafenoquine (TQ) is an 8-aminoquinoline (8AQ) that has been tested in several Phase II and Phase III clinical studies and is currently in late stage development as an anti-malarial prophylactic agent. NPC-1161B is a promising 8AQ in late preclinical development. It has recently been reported that the 8AQ drug primaquine requires metabolic activation by CYP 2D6 for efficacy in humans and in mice, highlighting the importance of pharmacogenomics in the target population when administering primaquine. A logical follow-up study was to determine whether CYP 2D activation is required for other compounds in the 8AQ structural class. In the present study, the anti-malarial activities of NPC-1161B and TQ were assessed against luciferase expressing Plasmodium berghei in CYP 2D knock-out mice in comparison with normal C57BL/6 mice (WT) and with humanized/CYP 2D6 knock-in mice by monitoring luminescence with an in vivo imaging system. These experiments were designed to determine the direct effects of CYP 2D metabolic activation on the anti-malarial efficacy of NPC-1161B and TQ. NPC-1161B and TQ exhibited no anti-malarial activity in CYP 2D knock-out mice when dosed at their ED100 values (1 mg/kg and 3 mg/kg, respectively) established in WT mice. TQ anti-malarial activity was partially restored in humanized/CYP 2D6 knock-in mice when tested at two times its ED100. The results reported here strongly suggest that metabolism of NPC-1161B and TQ by the CYP 2D enzyme class is essential for their anti-malarial activity. Furthermore, these results may provide a possible explanation for therapeutic failures for patients who do not respond to 8AQ treatment for relapsing malaria. Because CYP 2D6 is highly polymorphic, variable expression of this enzyme in humans represents a significant pharmacogenomic liability for 8AQs which require CYP 2D metabolic activation for efficacy, particularly for large-scale prophylaxis and eradication campaigns.

Seasonal expression of arginine vasotocin mRNA and its correlations to gonadal steroidogenic enzymes and sexually dimorphic coloration during sex reversal in the gilthead seabream (Sparus aurata).

PubMed

Reyes-Tomassini, José J; Wong, Ten-Tsao; Zohar, Yonathan

2017-06-01

Arginine vasotocin is a hormone produced in the hypothalamus of teleost fish that has been shown to regulate gonad development and sexual behavior. To study the role of arginine vasotocin in the gonadal cycle of the hermaphrodite gilthead seabream, Sparus aurata, we cloned the seabream arginine vasotocin (avt) complementary DNA (cDNA). We investigated the expression of brain avt throughout the gonad cycle using real-time quantitative PCR and compared its expression levels to the expression levels of two key gonadal steroidogenic enzymes, cyp19a1a and cyp11b2. In July, when the process of sex reversal is thought to begin, avt expression was elevated over the previous 2 months. Avt in the brain remained at or above the level of July until November then peaked again in December. There was no difference between males and females in the expression levels of brain avt throughout the year. However, only in ambisexual fish was the expression of the cyp19a1a gonadal aromatase correlated to the expression of avt in the brain. Cyp11b2 did not show any correlation to brain avt expression. We also found that females had more intense body coloration than males and that this intensity peaked prior to spawning. Avt expression and female coloration were positively correlated. The fact that brain avt expression was lowest during gonad quiescence, together with the observation of a correlation between brain avt with gonadal cyp19a1a and body coloration during that time suggests that avt may play a role during the process of sex reversal and spawning of the gilthead seabream.

Aromatase expression in a human osteoblastic cell line increases in response to prostaglandin E(2) in a dexamethasone-dependent fashion.

PubMed

Watanabe, M; Noda, M; Nakajin, S

2007-09-01

Recent progress supports the importance of local estrogen secretion in human bone tissue to increase and maintain bone-mineral density. In a previous report, we found that forskolin (FSK) synergistically induces aromatase (CYP19: a rate-limiting enzyme for estrogen synthesis) expression in dexamethasone (Dex) dependent manner in a human osteoblastic cell line, SV-HFO [Watanabe M, Ohno S, Nakajin S. Forskolin and dexamethasone synergistically induce aromatase (CYP19) expression in the human osteoblastic cell line SV-HFO. Eur J Endocrinol 2005;152:619-24]. In this report, we investigated whether prostaglandin (PG) E(2) induces estrogen production, in other words, if PGE(2) exerts the same effect as FSK because PGE(2) is the major prostanoid in the bone and is one of the key molecules in the osteoblast. We found PGE(2) up-regulates aromatase activity synergistically, but this up-regulation depends on Dex. CYP19 gene expression was also increased synergistically by Dex and PGE(2). Promoter I.4 was activated synergistically by PGE(2) and Dex. PGE(2) receptor, EP(1), EP(2) and EP(4) were involved in the up-regulation of aromatase activity in response to PGE(2) in a Dex-dependent manner. The cAMP-PKA pathway and Ca(2+) signaling pathway were involved in the up-regulation of aromatase activity in response to PGE(2). Furthermore, glucocorticoid response element on promoter I.4 sequence was an essential minimum requirement for its activity and synergism of PGE(2) and Dex. These findings are the first report on osteoblastic cell line which uses predominantly promoter I.4 to drive aromatase expression. These findings also suggest that endogenous PGE(2) produced in bone mainly may synergistically support local estrogen production in osteoblastic cells in the presence of glucocorticoid.

Pharmacogenetics of drug-metabolizing enzymes in US Hispanics

PubMed Central

Duconge, Jorge; Cadilla, Carmen L.; Ruaño, Gualberto

2015-01-01

Although the Hispanic population is continuously growing in the United States, they are underrepresented in pharmacogenetic studies. This review addresses the need for compiling available pharmacogenetic data in US Hispanics, discussing the prevalence of clinically relevant polymorphisms in pharmacogenes encoding for drug-metabolizing enzymes. CYP3A5*3 (0.245–0.867) showed the largest frequency in a US Hispanic population. A higher prevalence of CYP2C9*3, CYP2C19*4, and UGT2B7 IVS1+985 A>Gwas observed in US Hispanic vs. non-Hispanic populations. We found interethnic and intraethnic variability in frequencies of genetic polymorphisms for metabolizing enzymes, which highlights the need to define the ancestries of participants in pharmacogenetic studies. New approaches should be integrated in experimental designs to gain knowledge about the clinical relevance of the unique combination of genetic variants occurring in this admixed population. Ethnic subgroups in the US Hispanic population may harbor variants that might be part of multiple causative loci or in linkage-disequilibrium with functional variants. Pharmacogenetic studies in Hispanics should not be limited to ascertain commonly studied polymorphisms that were originally identified in their parental populations. The success of the Personalized Medicine paradigm will depend on recognizing genetic diversity between and within US Hispanics and the uniqueness of their genetic backgrounds. PMID:25431893

Cholesterol import and steroidogenesis are biosignatures for gastric cancer patient survival

PubMed Central

Chang, Wei-Chun; Huang, Shang-Fen; Lee, Yang-Ming; Lai, Hsueh-Chou; Cheng, Bi-Hua; Cheng, Wei-Chung; Ho, Jason Yen-Ping; Jeng, Long-Bin; Ma, Wen-Lung

2017-01-01

Androgens, estrogens, progesterone and related signals are reported to be involved in the pathology of gastric cancer. However, varied conclusions exist based on serum hormone levels, receptor expressions, and in vitro or in vivo studies. This report used a web-based gene survival analyzer to evaluate biochemical processes, including cholesterol importing via lipoprotein/receptors (L/R route), steroidogenic enzymes, and steroid receptors, in gastric cancer patients prognosis. The sex hormone receptors (androgen receptor, progesterone receptor, and estrogen receptor ESR1 or ESR2), L/R route (low/high-density lipoprotein receptors, LDLR/LRP6/SR-B1 and lipoprotein lipase, LPL) and steroidogenic enzymes (CYP11A1, HSD3B1, CYP17, HSD17B1, HSD3B1, CYP19A1 and SRD5A1) were associated with 5-year survival of gastric cancer patients. The AR, PR, ESR1 and ESR2 are progression promoters, as are the L/R route LDLR, LRP6, SR-B1 and LPL. It was found that CYP11A1, HSD3B1, CYP17, HSD17B1 and CYP19A1 promote progression, but dihydrotestosterone (DHT) converting enzyme SRD5A1 suppresses progression. Analyzing steroidogenic lipidome with a hazard ratio score algorithm found that CYP19A1 is the progression confounder in surgery, HER2 positive or negative patients. Finally, in the other patient cohort from TCGA, CYP19A1 was expressed higher in the tumor compared to that in normal counterparts, and also promoted progression. Lastly, exemestrane (type II aromatase inhibitor) dramatically suppress GCa cell growth in pharmacological tolerable doses in vitro. This work depicts a route-specific outside-in delivery of cholesterol to promote disease progression, implicating a host-to-tumor macroenvironmental regulation. The result indicating lipoprotein-mediated cholesterol entry and steroidogenesis are GCa progression biosignatures. And the exemestrane clinical trial in GCa patients of unmet medical needs is suggested. PMID:27893427

Cholesterol import and steroidogenesis are biosignatures for gastric cancer patient survival.

PubMed

Chang, Wei-Chun; Huang, Shang-Fen; Lee, Yang-Ming; Lai, Hsueh-Chou; Cheng, Bi-Hua; Cheng, Wei-Chung; Ho, Jason Yen-Ping; Jeng, Long-Bin; Ma, Wen-Lung

2017-01-03

Androgens, estrogens, progesterone and related signals are reported to be involved in the pathology of gastric cancer. However, varied conclusions exist based on serum hormone levels, receptor expressions, and in vitro or in vivo studies. This report used a web-based gene survival analyzer to evaluate biochemical processes, including cholesterol importing via lipoprotein/receptors (L/R route), steroidogenic enzymes, and steroid receptors, in gastric cancer patients prognosis. The sex hormone receptors (androgen receptor, progesterone receptor, and estrogen receptor ESR1 or ESR2), L/R route (low/high-density lipoprotein receptors, LDLR/LRP6/SR-B1 and lipoprotein lipase, LPL) and steroidogenic enzymes (CYP11A1, HSD3B1, CYP17, HSD17B1, HSD3B1, CYP19A1 and SRD5A1) were associated with 5-year survival of gastric cancer patients. The AR, PR, ESR1 and ESR2 are progression promoters, as are the L/R route LDLR, LRP6, SR-B1 and LPL. It was found that CYP11A1, HSD3B1, CYP17, HSD17B1 and CYP19A1 promote progression, but dihydrotestosterone (DHT) converting enzyme SRD5A1 suppresses progression. Analyzing steroidogenic lipidome with a hazard ratio score algorithm found that CYP19A1 is the progression confounder in surgery, HER2 positive or negative patients. Finally, in the other patient cohort from TCGA, CYP19A1 was expressed higher in the tumor compared to that in normal counterparts, and also promoted progression. Lastly, exemestrane (type II aromatase inhibitor) dramatically suppress GCa cell growth in pharmacological tolerable doses in vitro. This work depicts a route-specific outside-in delivery of cholesterol to promote disease progression, implicating a host-to-tumor macroenvironmental regulation. The result indicating lipoprotein-mediated cholesterol entry and steroidogenesis are GCa progression biosignatures. And the exemestrane clinical trial in GCa patients of unmet medical needs is suggested.

Effect of Brain CYP2B Inhibition on Brain Nicotine Levels and Nicotine Self-Administration

PubMed Central

Garcia, Kristine L P; Coen, Kathy; Miksys, Sharon; Lê, Anh Dzung; Tyndale, Rachel F

2015-01-01

The CYP2B enzyme is expressed in human and rat brain, and metabolizes many CNS-acting drugs. The gene that encodes human CYP2B6 is highly polymorphic, where the variation in brain enzyme levels could result in altered brain drug levels. CYP2B can metabolize nicotine, the main psychoactive ingredient in cigarettes; if altered brain CYP2B activity can influence nicotine brain levels, it could influence nicotine-mediated behaviors. To investigate this, a mechanism-based inhibitor selective for CYP2B, C8-xanthate (20 μg), was administered intracerebroventricularly (ICV) into the brain of rats, and 22 h later, nicotine levels were measured by in vivo microdialysis following nicotine (150 μg/kg intravenous). Brain nicotine levels from 15 to 30 min and the AUC0–45min were both twofold higher (p<0.05) with C8-xanthate vs vehicle pretreatment; there was no difference in peripheral nicotine levels. Rats were then given ICV pretreatment with C8-xanthate/ASCF and underwent intravenous nicotine self-administration with 3.75–30 μg/kg per infusion dose. C8-xanthate pretreatment increased responding in progressive ratio (15 μg/kg per infusion dose, p<0.05). In a separate cohort, C8-xanthate increased the percentage of rats that acquired self-administration (7.5 μg/kg per infusion dose, p<0.05) from 40% after vehicle pretreatment to 100%, with no difference in peripheral nicotine levels measured at the end of behavior. In a third cohort, C8-xanthate increased the number of sessions required to meet extinction criteria (p<0.05). Together these data demonstrate that the brain CYP2B activity can influence nicotine brain levels and subsequent behaviors independent of hepatic metabolism. This suggests that human smokers with variable CYP2B brain levels could have different nicotine levels and reinforcement, which might have a role in smoking behaviors and dependence. PMID:25652250

Role of Adaptor Protein Toll-Like Interleukin Domain Containing Adaptor Inducing Interferon β in Toll-Like Receptor 3- and 4-Mediated Regulation of Hepatic Drug Metabolizing Enzyme and Transporter Genes.

PubMed

Shah, Pranav; Omoluabi, Ozozoma; Moorthy, Bhagavatula; Ghose, Romi

2016-01-01

The expressions and activities of hepatic drug-metabolizing enzymes and transporters (DMETs) are altered during infection and inflammation. Inflammatory responses in the liver are mediated primarily by Toll-like receptor (TLR)-signaling, which involves recruitment of Toll/interleukin (IL)-1 receptor (TIR) domain containing adaptor protein (TIRAP) and TIR domain containing adaptor inducing interferon (IFN)-β (TRIF) that eventually leads to induction of proinflammatory cytokines and mitogen-activated protein kinases (MAPKs). Lipopolysaccharide (LPS) activates the Gram-negative bacterial receptor TLR4 and polyinosinic:polycytidylic acid (polyI:C) activates the viral receptor TLR3. TLR4 signaling involves TIRAP and TRIF, whereas TRIF is the only adaptor protein involved in the TLR3 pathway. We have shown previously that LPS-mediated downregulation of DMETs is independent of TIRAP. To determine the role of TRIF, we treated TRIF(+/+) and TRIF(-/-) mice with LPS or polyI:C. LPS downregulated (∼40%-60%) Cyp3a11, Cyp2a4, Ugt1a1, Mrp2 mRNA levels, whereas polyI:C downregulated (∼30%-60%) Cyp3a11, Cyp2a4, Cyp1a2, Cyp2b10, Ugt1a1, Mrp2, and Mrp3 mRNA levels in TRIF(+/+) mice. This downregulation was not attenuated in TRIF(-/-) mice. Induction of cytokines by LPS was observed in both TRIF(+/+) and TRIF(-/-) mice. Cytokine induction was delayed in polyI:C-treated TRIF(-/-) mice, indicating that multiple mechanisms mediating polyI:C signaling exist. To assess the role of MAPKs, primary hepatocytes were pretreated with specific inhibitors before treatment with LPS/polyI:C. We found that only the c-jun-N-terminal kinase (JNK) inhibitor attenuated the down-regulation of DMETs. These results show that TRIF-independent pathways can be involved in the downregulation of DMETs through TLR4 and 3. JNK-dependent mechanisms likely mediate this downregulation. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

Activity of xenobiotic-metabolizing enzymes in the liver of rats with multi-vitamin deficiency.

PubMed

Tutelyan, Victor A; Kravchenko, Lidia V; Aksenov, Ilya V; Trusov, Nikita V; Guseva, Galina V; Kodentsova, Vera M; Vrzhesinskaya, Oksana A; Beketova, Nina A

2013-01-01

The purpose of the study was to determine how multi-vitamin deficiency affects xenobiotic-metabolizing enzyme (XME) activities in the rat liver. Vitamin levels and XME activities were studied in the livers of male Wistar rats who were fed for 4 weeks with semi-synthetic diets containing either adequate (100 % of recommended vitamin intake) levels of vitamins (control), or decreased vitamin levels (50 % or 20 % of recommended vitamin intake). The study results have shown that moderate vitamin deficiency (50 %) leads to a decrease of vitamin A levels only, and to a slight increase, as compared with the control, in the following enzyme activities: methoxyresorufin O-dealkylase (MROD) activity of CYP1 A2 - by 34 % (p < 0.05), UDP-glucuronosyl transferase - by 26 % (p < 0.05), and quinone reductase - by 55 % (p < 0.05). Profound vitamin deficiency (20 %) led to a decrease of vitamins A, E, B1, B2, and C, and enzyme activities in the liver: MROD - to 78 % of the control level (p < 0.05), 4-nitrophenol hydroxylase - to 74 % (p < 0.05), heme oxygenase-1 - to 83 % (p < 0.05), and quinone reductase - to 60 % (p < 0.05). At the same time, the UDP-glucuronosyl transferase activity and ethoxyresorufin O-dealkylase activity of CYP1A1, pentoxyresorufin O-dealkylase activity of CYP2B1/2 and 6β-testosterone hydroxylase, as well as the total activity of glutathione transferase did not differ from the control levels. The study has demonstrated that profound multi-vitamin deficiency is associated with a decrease in the expression of CYP1A2 and CYP3A1 mRNAs to 62 % and 79 %, respectively. These data indicated that a short-term but profound multi-vitamin deficiency in rats leads to a decrease in the activities and expression of the some XME that play an important role in detoxification of xenobiotics and metabolism of drugs and antioxidant protection.

Inactivation of CYP2A6 by the Dietary Phenylpropanoid trans-Cinnamic Aldehyde (Cinnamaldehyde) and Estimation of Interactions with Nicotine and Letrozole

PubMed Central

Chan, Jeannine; Oshiro, Tyler; Thomas, Sarah; Higa, Allyson; Black, Stephen; Todorovic, Aleksandar; Elbarbry, Fawzy

2016-01-01

Human exposure to trans-cinnamic aldehyde [t-CA; cinnamaldehyde; cinnamal; (E)-3-phenylprop-2-enal] is common through diet and through the use of cinnamon powder for diabetes and to provide flavor and scent in commercial products. We evaluated the likelihood of t-CA to influence metabolism by inhibition of P450 enzymes. IC50 values from recombinant enzymes indicated that an interaction is most probable for CYP2A6 (IC50 = 6.1 µM). t-CA was 10.5-fold more selective for human CYP2A6 than for CYP2E1; IC50 values for P450s 1A2, 2B6, 2C9, 2C19, 2D6, and 3A4 were 15.8-fold higher or more. t-CA is a type I ligand for CYP2A6 (KS = 14.9 µM). Inhibition of CYP2A6 by t-CA was metabolism-dependent; inhibition required NADPH and increased with time. Glutathione lessened the extent of inhibition modestly and statistically significantly. The carbon monoxide binding spectrum was dramatically diminished after exposure to NADPH and t-CA, suggesting degradation of the heme or CYP2A6 apoprotein. Using a static model and mechanism-based inhibition parameters (KI = 18.0 µM; kinact = 0.056 minute−1), changes in the area under the concentration-time curve (AUC) for nicotine and letrozole were predicted in the presence of t-CA (0.1 and 1 µM). The AUC fold-change ranged from 1.1 to 3.6. In summary, t-CA is a potential source of pharmacokinetic variability for CYP2A6 substrates due to metabolism-dependent inhibition, especially in scenarios when exposure to t-CA is elevated due to high dietary exposure, or when cinnamon is used as a treatment of specific disease states (e.g., diabetes). PMID:26851241

Randomized Trial Comparing Esomeprazole and Rabeprazole in First-line Eradication Therapy for Helicobacter pylori Infection based on the Serum Levels of Pepsinogens.

PubMed

Shimoyama, Tadashi; Chinda, Daisuke; Sawada, Yoshihiko; Komai, Kazuo; Chiba, Hironobu; Saito, Yoshiharu; Sasaki, Yoshio; Matsuzaka, Masashi; Fukuda, Shinsaku

2017-01-01

Objective CYP2C19 metabolic activity influences the efficacy of Helicobacter pylori eradication therapies comprising PPIs. Rabeprazole (RPZ) and esomeprazole (EPZ) are PPIs not extensively metabolized by CYP2C19. The aim of this study was to elucidate whether or not first-line triple therapies using RPZ or EPZ are equally effective in Japanese patients with different CYP2C19 genotypes. Methods Two-hundred patients infected with H. pylori were randomized to receive one of the following regimens: amoxicillin (750 mg), clarithromycin (200 mg), and either esomeprazole (20 mg) (EAC group) or rabeprazole (10 mg) (RAC group), twice a day for one week. The CYP2C19 polymorphisms were determined by polymerase chain reaction and the serum level of pepsinogens was measured. Results The eradication rates of the EAC and RAC regimens were 79.8% (95% confidential interval: 71.7-89.0%) and 74.7% (66.0-83.4%), respectively, in a per protocol (PP) analysis (p=0.488). The eradication rates of the EAC and RAC regimens were not significantly different between patients with the homo EM genotype (p=0.999) or hetero IM or PM genotypes (p=0.286). A lower PG I/II ratio was associated with lower eradication rates (p=0.025). Conclusion Although the eradication rate was less than 80%, the EAC and RAC regimens were equally effective in each CYP2C19 genotype group. The PG I/II ratio was associated with the results of EAC and RAC therapy in this series of patients.

Randomized Trial Comparing Esomeprazole and Rabeprazole in First-line Eradication Therapy for Helicobacter pylori Infection based on the Serum Levels of Pepsinogens

PubMed Central

Shimoyama, Tadashi; Chinda, Daisuke; Sawada, Yoshihiko; Komai, Kazuo; Chiba, Hironobu; Saito, Yoshiharu; Sasaki, Yoshio; Matsuzaka, Masashi; Fukuda, Shinsaku

2017-01-01

Objective CYP2C19 metabolic activity influences the efficacy of Helicobacter pylori eradication therapies comprising PPIs. Rabeprazole (RPZ) and esomeprazole (EPZ) are PPIs not extensively metabolized by CYP2C19. The aim of this study was to elucidate whether or not first-line triple therapies using RPZ or EPZ are equally effective in Japanese patients with different CYP2C19 genotypes. Methods Two-hundred patients infected with H. pylori were randomized to receive one of the following regimens: amoxicillin (750 mg), clarithromycin (200 mg), and either esomeprazole (20 mg) (EAC group) or rabeprazole (10 mg) (RAC group), twice a day for one week. The CYP2C19 polymorphisms were determined by polymerase chain reaction and the serum level of pepsinogens was measured. Results The eradication rates of the EAC and RAC regimens were 79.8% (95% confidential interval: 71.7-89.0%) and 74.7% (66.0-83.4%), respectively, in a per protocol (PP) analysis (p=0.488). The eradication rates of the EAC and RAC regimens were not significantly different between patients with the homo EM genotype (p=0.999) or hetero IM or PM genotypes (p=0.286). A lower PG I/II ratio was associated with lower eradication rates (p=0.025). Conclusion Although the eradication rate was less than 80%, the EAC and RAC regimens were equally effective in each CYP2C19 genotype group. The PG I/II ratio was associated with the results of EAC and RAC therapy in this series of patients. PMID:28674348

From molecule to behavior: Brain aromatase (cyp19a1b) characterization, expression analysis and its relation with social status and male agonistic behavior in a Neotropical cichlid fish.

PubMed

Ramallo, Martín R; Morandini, Leonel; Birba, Agustina; Somoza, Gustavo M; Pandolfi, Matías

2017-03-01

The enzyme aromatase, responsible for the conversion of C19 androgens to C18 estrogens, exists as two paralogue copies in teleost fish: Cyp19a1a mostly expressed in the gonads, referred as gonadal aromatase, and Cyp19a1b, mostly expressed in the brain, accordingly known as brain aromatase. The neural localization of Cyp19a1b is greatly contained within the social behavior network and mesolimbic reward system in fish, suggesting a strong role of estrogen synthesis in the regulation of social behavior. In this work we aimed to analyze the variation in cyp19a1b expression in brain and pituitary of males of a highly social cichlid, Cichlasoma dimerus (locally known as chanchita), and its relation with inter-individual variability in agonistic behavior in a communal social environment. We first characterized chanchita's cyp19a1b mRNA and deduced amino acid sequence, which showed a high degree of conservation when compared to other teleost brain aromatase sequences, and its tissue expression patterns. Within the brain, Cyp19a1b was solely detected at putative radial glial cells of the forebrain, close to the brain ventricles. We then studied the relative expression levels of cyp19a1b by Real Time PCR in the brain and pituitary of males of different social status, territorial vs. non-territorial, and its relationship with an index of agonistic behavior. We found that even though, brain aromatase expression did not differ between types of males, pituitary cyp19a1b expression levels positively correlated with the index of agonistic behavior. This suggests a novel role of the pituitary in the regulation of social behavior by local estrogen synthesis. Copyright © 2017 Elsevier Inc. All rights reserved.

Characterization of the biotransformation pathways of clomiphene, tamoxifen and toremifene as assessed by LC-MS/(MS) following in vitro and excretion studies.

PubMed

Mazzarino, Monica; Biava, Mariangela; de la Torre, Xavier; Fiacco, Ilaria; Botrè, Francesco

2013-06-01

The use of selective oestrogen receptor modulators has been prohibited since 2005 by the World Anti-Doping Agency regulations. As they are extensively cleared by hepatic and intestinal metabolism via oxidative and conjugating enzymes, a complete investigation of their biotransformation pathways and kinetics of excretion is essential for the anti-doping laboratories to select the right marker(s) of misuse. This work was designed to characterize the chemical reactions and the metabolizing enzymes involved in the metabolic routes of clomiphene, tamoxifen and toremifene. To determine the biotransformation pathways of the substrates under investigation, urine samples were collected from six subjects (three females and three males) after oral administration of 50 mg of clomiphene citrate or 40 mg of tamoxifen or 60 mg of toremifene, whereas the metabolizing enzymes were characterized in vitro, using expressed cytochrome P450s and uridine diphosphoglucuronosyltransferases. The separation, identification and determination of the compounds formed in the in vivo and in vitro experiments were carried out by liquid chromatography coupled with mass spectrometry techniques using different acquisition modes. Clomiphene, tamoxifen and toremifene were biotransformed to 22, 23 and 18 metabolites respectively, these phase I reactions being catalyzed mainly by CYP3A4 and CYP2D6 isoforms and, to a lesser degree, by CYP3A5, CYP2B6, CYP2C9, CYP2C19 isoforms. The phase I metabolic reactions include hydroxylation in different positions, N-oxidation, dehalogenation, carboxylation, hydrogenation, methoxylation, N-dealkylation and combinations of them. In turn, most of the phase I metabolites underwent conjugation reaction to form the corresponding glucuro-conjugated mainly by UGT1A1, UGT1A3, UGT1A4, UGT2B7, UGT2B15 and UGT2B17 isoenzymes.

Safety assessment of selected medicinal food plants used in Ayurveda through CYP450 enzyme inhibition study.

PubMed

Kar, Amit; Pandit, Subrata; Mukherjee, Kakali; Bahadur, Shiv; Mukherjee, Pulok K

2017-01-01

Andrographis paniculata, Bacopa monnieri and Centella asiatica are mentioned in Ayurveda for the management of neurodegenerative disorders. These plants and their phytomolecules, such as andrographolide, bacoside A and asiaticoside, were studied for their inhibition potential on pooled CYP450 as well as human CYP3A4, CYP2D6, CYP2C9 and CYP1A2 by CYP-CO complex assay and fluorogenic assay respectively followed by IC 50 determination. Quantification of bioactive compounds present in the extracts was done by RP-HPLC. Heavy metal content in the selected medicinal plants was determined by atomic absorption spectroscopy. CYP-CO complex assay indicated significantly less inhibition potential than standard inhibitor (P < 0.05 and above). A. paniculata showed highest inhibitory activity against CYP3A4 and CYP2D6 (IC 50 = 63.06 ± 1.35 µg mL -1 ; 88.80 ± 3.32 µg mL -1 ), whereas C. asiatica and B. monnieri showed least inhibitory activity against CYP1A2 (IC 50 = 288.83 ± 1.61 µg mL -1 ) and CYP2C9 (184.68 ± 3.79 µg mL -1 ), respectively. In all cases the extract showed higher inhibition than the single bioactive compounds. The heavy metals content in the plant extracts were within the permissible limits. The findings suggested that selected food plants and bioactive compounds contributed negligible interaction potential with CYP isozymes and may not possess any harmful effect with regard to their therapeutic application. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Single or Multiple Access Channels to the CYP450s Active Site? An Answer from Free Energy Simulations of the Human Aromatase Enzyme.

PubMed

Magistrato, Alessandra; Sgrignani, Jacopo; Krause, Rolf; Cavalli, Andrea

2017-05-04

Cytochromes P450 (CYP450s), in particular, CYP19A1 and CYP17A1, are key clinical targets of breast and prostate anticancer therapies, critical players in drug metabolism, and their overexpression in tumors is associated with drug resistance. In these enzymes, ligand (substrates, drugs) metabolism occurs in deeply buried active sites accessible only via several grueling channels, whose exact biological role remains unclear. Gaining direct insights on the mechanism by which ligands travel in and out is becoming increasingly important given that channels are involved in the modulation of binding/dissociation kinetics and the specificity of ligands toward a CYP450. This has profound implications for enzymatic efficiency and drug efficacy/toxicity. Here, by applying free energy methods, for a cumulative simulation time of 20 μs, we provide detailed atomistic characterization and free energy profiles of the entry/exit routes preferentially followed by a substrate (androstenedione) and a last-generation inhibitor (letrozole) to/from the catalytic site of CYP19A1 (the human aromatase (HA) enzyme), a key clinical target against breast cancer, studied here as prototypical CYP450. Despite the remarkably different size/shape/hydrophobicity of the ligands, two channels appear accessible to their entrance, while only one exit route appears to be preferential. Our study shows that the preferential paths may be conserved among different CYP450s. Moreover, our results highlight that, at least in the case of HA, ligand channeling is associated with large enzyme structural rearrangements. A wise choice of the computational method and very long simulations are, thus, required to obtain fully converged quantitative free energy profiles, which might be used to design novel biocatalysts or next-generation cytochrome inhibitors with an in silico tuned K m .

New Psychoactive Substances 3-Methoxyphencyclidine (3-MeO-PCP) and 3-Methoxyrolicyclidine (3-MeO-PCPy): Metabolic Fate Elucidated with Rat Urine and Human Liver Preparations and their Detectability in Urine by GC-MS, “LC-(High Resolution)-MSn” and “LC-(High Resolution)-MS/MS”

PubMed Central

Michely, Julian A.; Manier, Sascha K.; Caspar, Achim T.; Brandt, Simon D.; Wallach, Jason; Maurer, Hans. H.

2017-01-01

Background: 3-Methoxyphencyclidine (3-MeO-PCP) and 3-methoxyrolicyclidine (3-MeO-PCPy) are two new psychoactive substances (NPS). The aims of the present study were the elucidation of their metabolic fate in rat and pooled human liver microsomes (pHLM) the identification of the cytochrome P450 (CYP) isoenzymes involved and the detectability using standard urine screening approaches (SUSA) after intake of common users’ doses using gas chromatography-mass spectrometry (GC-MS) liquid chromatography-multi-stage mass spectrometry (LC-MSn) and liquid chromatography-high-resolution tandem mass spectrometry (LC-HR-MS/MS) Methods: For metabolism studies rat urine samples were treated by solid phase extraction or simple precipitation with or without previous enzymatic conjugate cleavage. After analyses via LC-HR-MSn the phase I and II metabolites were identified Results: Both drugs showed multiple aliphatic hydroxylations at the cyclohexyl ring and the heterocyclic ring single aromatic hydroxylation carboxylation after ring opening O-demethylation and glucuronidation. The transferability from rat to human was investigated by pHLM incubations where O-demethylation and hydroxylation were observed. The involvement of the individual CYP enzymes in the initial metabolic steps was investigated after single CYP incubations. For 3-MeO-PCP CYP 2B6 was responsible for aliphatic hydroxylations and CYP 2C19 and CYP 2D6 for O-demethylation. For 3-MeO-PCPy aliphatic hydroxylation was again catalyzed by CYP 2B6 and O-demethylation by CYP 2C9 and CYP 2D6 Conclusions: As only polymorphically expressed enzymes were involved pharmacogenomic variations might occur but clinical data are needed to confirm the relevance. The detectability studies showed that the authors’ SUSAs were suitable for monitoring the intake of both drugs using the identified metabolites PMID:27758707

Cytochrome P450-inhibitory activity of parabens and phthalates used in consumer products.

PubMed

Ozaki, Hitomi; Sugihara, Kazumi; Watanabe, Yoko; Ohta, Shigeru; Kitamura, Shigeyuki

2016-01-01

The in vitro cytochrome P450 (CYP)-inhibitory effects of 11 parabens and 7 phthalates used in consumer products, as well as their hydrolytic metabolites, were investigated, using rat liver microsomes as an enzyme source. The effects on individual CYP isozymes were evaluated by assaying inhibition of activities towards specific substrates, i.e., ethoxyresorufin O-dealkylase (EROD), methoxyresorufin O-dealkylase (MROD), pentoxyresorufin O-dealkylase (PROD), 7-benzyloxy-4-trifluoromethylcoumarin dealkylase (BFCD), 7-methoxy-4-trifluoromethylcoumarin dealkylase (MFCD) and 7-ethoxy-4-trifluoromethylcoumarin dealkylase (EFCD) activities. These activities were dose-dependently inhibited, most potently by medium-side-chain parabens (C6-9) and phthalates (C4-6), and less potently by shorter- and longer-side-chain esters. The hydrolytic product of parabens, 4-hydroxybenzoic acid, was not inhibitory, while those of phthalates, phthalic acid monoesters, showed lower inhibitory activity than the parent phthalates. Parabens showed relatively potent inhibition of MFCD activity, considered to be mainly due to CYP2C, and phthalates showed relatively potent inhibition of PROD activity, considered to be mainly due to CYP2B.

Rat oesophageal cytochrome P450 (CYP) monooxygenase system: comparison to the liver and relevance in N-nitrosodiethylamine carcinogenesis.

PubMed

Pinto, L F; Moraes, E; Albano, R M; Silva, M C; Godoy, W; Glisovic, T; Lang, M A

2001-11-01

N-nitrosodiethylamine (NDEA) is able to induce tumours in the rat oesophagus. It has been suggested that this could be due to tissue specific expression of NDEA activating cytochrome P450 enzymes. We investigated this by characterizing the oesophageal monooxygenase complex of male Wistar rats and comparing it with that of the liver. Total amount of cytochrome P450, NADPH P450 reductase, cytochrome b5 and cytochrome b5 reductase of the oesophageal mucosa was approximately 7% of what was found in the liver. In addition, major differences were found in the cytochrome P450 isoenzyme composition between these organs: CYP 2B1/2B2 and CYP3A were found only in the liver, whereas CYP1A1 was constitutively expressed only in the oesophagus. Of the two well-known nitrosamine metabolizing enzymes, CYP2A3 was found only in the oesophagus whereas CYP2E1 was exclusively expressed in the liver. Catalytic studies, western blotting and RT-PCR analyses confirmed the expression of CYP2A3 in the oesophagus. CYP2A enzymes are known to be good catalysts of NDEA metabolism. Oesophageal microsomes had a K(m) for NDEA metabolism, which was about one-third of that of hepatic microsomes, but they showed similar activities when compared per nmol of total P450. NDEA activity in the oesophagus was significantly increased by coumarin (CO), which also induced oesophageal CYP2A3. Immunoinhibition of the microsomal NDEA activity showed that up to 70% of this reaction is catalysed by CYP2A3 in the oesophagus, whereas no inhibition of the hepatic NDEA activity could be achieved by the anti-CYP2A5 antibody. NDEA, but not N-nitrosodimethylamine (NDMA) inhibited the oesophageal metabolism of CO. The results of the present investigation show major differences in the enzyme composition of the oesophageal and hepatic monooxygenase complexes, and are in accordance with the hypothesis that the NDEA organotropism could, to a large extent, be due to the tissue specific expression of the activating enzymes.

Characterization of moclobemide N-oxidation in human liver microsomes.

PubMed

Hoskins, J; Shenfield, G; Murray, M; Gross, A

2001-07-01

1. Moclobemide underdergoes morpholine ring N-oxidation to form a major metabolite in plasma Rol2-5637. 2. The kinetics of moclobemide N-oxidation in human liver microsomes (HLM) (n = 6) have been investigated and the mixed-function oxidase enzymes catalysing this reaction have been identified using inhibition, enzyme correlation, altered pH and heat pretreatment experiments. 3. N-oxidation followed single enzyme Michealis-Menten kinetics (0.02-4.0 mm). Km app and Vmax ranged from 0.48 to 1.35 mM (mean +/- SD) 0.77 +/- 0.34 mM) and 0.22 to 2.15 nmol mg(-1) min(-1) (1.39 +/- 0.80 nmol mg(-1) respectively. 4. The N-oxidation of moclobemide strongly correlated with benzydamine N-oxidation a probe reaction for flavin-containing monoxygenase (FMO) activity (0.1 mM moclobemide, rs = 0.81, p < 0.005; 4 mM moclobemide, rs = 0.94, p = 0.0001). Correlations were observed between moclobemide N-oxidation and specific cytochromre P450 (CYP) activities at both moclobemide concentrations (0.1 mM moclobemide, CYP2C19 0.66, p < 0.05; 4 mM moclobemide, CYP2E1 rs = 0.56, p < 0.05). 5. The general P450 inhibitor, N-benzylimidazole, did not affect the rate of Rol2-5637 formation (0% inhibition versus control) (at 1.3 mM moclobemide. Furthermore, the rate of Ro12-5637 formation in HLM was unaffected by inhibitors Or substrates of specific P450s (< 10% inhibition versus control). 6. Heat pretreatment of HLM in the absence of NADPH (inactivating FMOs) resulted in 97% inhibition of Ro12-5637 formation. N-oxidation activity was greatest when incubated at pH 8.5. These results ilre consistent with the reaction being FMO medialtetd . 7. In conclusion, moclobemide N-oxidation activity has been observed in HLM in vitro and the reaction is predominantly catalysed by FMOs with a potentially small contribution from cytochrome P450 isoforms.

Biochemical Mechanisms for Geographical Adaptations to Novel Toxin Exposures in Butterflyfish

PubMed Central

Knuston, Sean; Slattery, Marc; Ankisetty, Sridevi; Goldstone, Jared V.; Watanabe, Kayo; Hoh, Eunha; Gadepalli, Rama S.; Rimoldi, John M.; Ostrander, Gary K.

2016-01-01

Some species of butterflyfish have had preyed upon corals for millions of years, yet the mechanism of butterflyfish specialized coral feeding strategy remains poorly understood. Certain butterflyfish have the ability to feed on allelochemically rich soft corals, e.g. Sinularia maxima. Cytochrome P450 (CYP) is the predominant enzyme system responsible for the detoxification of dietary allelochemicals. CYP2-like and CYP3A-like content have been associated with butterflyfish that preferentially consumes allelochemically rich soft corals. To investigate the role of butterflyfish CYP2 and CYP3A enzymes in dietary preference, we conducted oral feeding experiments using homogenates of S. maxima and a toxin isolated from the coral in four species of butterflyfish with different feeding strategies. After oral exposure to the S. maxima toxin 5-episinulaptolide (5ESL), which is not normally encountered in the Hawaiian butterflyfish diet, an endemic specialist, Chaetodon multicinctus experienced 100% mortality compared to a generalist, Chaetodon auriga, which had significantly more (3–6 fold higher) CYP3A-like basal content and catalytic activity. The specialist, Chaetodon unimaculatus, which preferentially feed on S. maxima in Guam, but not in Hawaii, had 100% survival, a significant induction of 8–12 fold CYP3A-like content, and an increased ability (2-fold) to metabolize 5ESL over other species. Computer modeling data of CYP3A4 with 5ESL were consistent with microsomal transformation of 5ESL to a C15-16 epoxide from livers of C. unimaculatus. Epoxide formation correlated with CYP3A-like content, catalytic activity, induction, and NADPH-dependent metabolism of 5ESL. These results suggest a potentially important role for the CYP3A family in butterflyfish-coral diet selection through allelochemical detoxification. PMID:27136924

The regulation of cytochrome P450 2E1 during LPS-induced inflammation in the rat

DOE Office of Scientific and Technical Information (OSTI.GOV)

Abdulla, Dalya; Goralski, Kerry B.; College of Pharmacy, Burbidge Building, Dalhousie University, Halifax, Nova Scotia, B3H 3J5

2006-10-01

It is well known that inflammatory and infectious conditions differentially regulate cytochrome P450 (P450)-mediated drug metabolism in the liver. We have previously outlined a potential pathway for the downregulation in hepatic cytochrome P450 following LPS-mediated inflammation in the CNS (Abdulla, D., Goralski, K.B., Garcia Del Busto Cano, E., Renton, K.W., 2005. The signal transduction pathways involved in hepatic cytochrome P450 regulation in the rat during an LPS-induced model of CNS inflammation. Drug Metab. Dispos). The purpose of this study was to outline the effects of LPS-induced peripheral and central nervous system inflammation on hepatic cytochrome P450 2E1 (CYP2E1) in vivo,more » an enzyme that plays an important role in various physiological and pathological states. We report an increase in hepatic mRNA expression of CYP2E1 that occurred as early as 2-3 h following either the intraperitoneal (i.p.) injection of 5 mg/kg LPS or i.c.v. administration of 25 {mu}g of LPS. This increase in CYP2E1 mRNA expression was sustained for 24 h. In sharp contrast to the increase in hepatic CYP2E1 mRNA, we observed a significant reduction in the catalytic activity of this enzyme 24 h following either the i.c.v. or i.p. administration of LPS. Cycloheximide or actinomycin-D did not change the LPS-mediated downregulation in hepatic CYP2E1 catalytic activity. Our results support the idea that LPS acts at two different levels to regulate hepatic CYP2E1: a transcriptional level to increase CYP2E1 mRNA expression and a post-transcriptional level to regulate CYP2E1 protein and activity.« less

Disorganized Steroidogenesis in Adrenocortical Carcinoma, a Case Study.

PubMed

Uchida, Toyoyoshi; Nishimoto, Koshiro; Fukumura, Yuki; Asahina, Miki; Goto, Hiromasa; Kawano, Yui; Shimizu, Fumitaka; Tsujimura, Akira; Seki, Tsugio; Mukai, Kuniaki; Kabe, Yasuaki; Suematsu, Makoto; Gomez-Sanchez, Celso E; Yao, Takashi; Horie, Shigeo; Watada, Hirotaka

2017-03-01

Most adrenocortical carcinomas (ACCs) produce excessive amounts of steroid hormones including aldosterone, cortisol, and steroid precursors. However, aldosterone- and cortisol-producing cells in ACCs have not yet been immunohistochemically described. We present a case of ACC causing mild primary aldosteronism and subclinical Cushing's syndrome. Removal of the tumor cured both conditions. In order to examine the expression patterns of the steroidogenic enzymes responsible for adrenocortical hormone production, 10 tumor portions were immunohistochemically analyzed for aldosterone synthase (CYP11B2), 11β-hydroxylase (CYP11B1, cortisol-synthesizing enzyme), 3β-hydroxysteroid dehydrogenase (3βHSD, upstream enzyme for both CYP11B2 and CYP11B1), and 17α-hydroxylase/C17-20 lyase (CYP17, upstream enzyme for CYP11B1, but not for CYP11B1). CYP11B2, CYP11B1, and 3βHSD were expressed sporadically, and their expression patterns varied significantly among the different tumor portions examined. The expression of these enzymes was random and not associated with each other. CYP17 was expressed throughout the tumor, even in CYP11B2-positive cells. Small tumor cell populations were aldosterone- or cortisol-producing cells, as judged by 3βHSD coinciding with either CYP11B2 or CYP11B1, respectively. These results suggest that the tumor produced limited amounts of aldosterone and cortisol due to the lack of the coordinated expression of steroidogenic enzymes, which led to mild clinical expression in this case. We delineated the expression patterns of steroidogenic enzymes in ACC. The coordinated expression of steroidogenic enzymes in normal and adenoma cells was disturbed in ACC cells, resulting in the inefficient production of steroid hormones in relation to the large tumor volume.

Enantioselective analysis of citalopram and escitalopram in postmortem blood together with genotyping for CYP2D6 and CYP2C19.

PubMed

Carlsson, Björn; Holmgren, Anita; Ahlner, Johan; Bengtsson, Finn

2009-03-01

Citalopram is marketed as a racemate (50:50) mixture of the S(+)-enantiomer and R(-)-enantiomer and the active S(+)-enantiomer (escitalopram) that possess inhibitory effects. Citalopram was introduced in Sweden in 1992 and is the most frequently used antidepressant to date in Sweden. In 2002, escitalopram was introduced onto the Swedish market for treatment of depression and anxiety disorders. The main objective of this study was to investigate S(+)-citalopram [i.e., the racemic drug (citalopram) or the enantiomer (escitalopram)] present in forensic autopsy cases positive for the presence of citalopram in routine screening using a non-enantioselective bioanalytical method. Fifty out of the 270 samples found positive by gas chromatography-nitrogen-phosphorus detection were further analyzed using enantioselective high-performance liquid chromatography. The 50 cases were genotyped for CYP2D6 and CYP2C19, as these isoenzymes are implicated in the metabolism of citalopram and escitalopram. In samples positive for racemic citalopram using the screening method for forensic autopsy cases, up to 20% would have been misinterpreted in the absence of an enantioselective method. An enantioselective method is thus necessary for correct interpretation of autopsy cases, after the enantiomer has been introduced onto the market. The percentage of poor metabolizers was 6% for CYP2D6 and 8% for CYP2C19.

Genetic polymorphism of (S)-mephenytoin 4′-hydroxylation in populations of African descent

PubMed Central

Xie, H G; Kim, R B; Stein, C M; Wilkinson, G R; Wood, A J J

1999-01-01

Aims The frequency of CYP2C19 poor metabolizers (PMs) in populations of African descent has been reported to range from 1.0% to 35.4%. In order to determine with greater certainty the frequency of CYP2C19 PMs in such black populations we have performed a meta-analysis of the studies. Methods Relevant data on the frequency of both the PM phenotype of probe drugs (mephenytoin, omeprazole, and proguanil), and the distribution frequencies of CYP2C19 alleles and genotypes in black populations were summarized and reanalysed using a meta-analytical approach. Results Of nine reported studies two were excluded because of significant heterogeneity (χ2 = 115, P < 0.0001). The combined data from the remaining seven studies showed that the frequency of the PM phenotype in 922 healthy unrelated black Africans and black Americans ranged from 1.0% to 7.5% (n = 7 for combined data) with an overall frequency being 3.9% (36 of 922; 95%CI: 2.7%–5.2%). The frequency of the PM genotypes in blacks was 3.7% (36 of 966; 95%CI: 2.5%–4.9%), in agreement with the frequency of the PM phenotype. In the extensive metabolizers (EMs) 29% (271 of 930) were heterozygotes (wt/m). The observed frequencies of the three Mendelian genotypes were 0.68 for wt/wt, 0.28 for wt/m, and 0.04 for m/m. The allelic distribution was appropriate at 82.3% (95%CI: 80.5%-83.9%) for CYP2C19*1, 17.3% (95%CI:15.7%–19.0%) for CYP2C19*2 (m1), and 0.4% (95%CI: 0.1%–0.7%) for CYP2C19*3 (m2) in these populations. Conclusions We conclude that subjects of African ancestry have a low frequency of the CYP2C19 PM phenotype and genotype; that the defective CYP2C19 alleles are uncommon, and that a small proportion of heterozygotes exists in the EM subpopulation. PMID:10510153

Sex-dependent alteration of cardiac cytochrome P450 gene expression by doxorubicin in C57Bl/6 mice.

PubMed

Grant, Marianne K O; Seelig, Davis M; Sharkey, Leslie C; Zordoky, Beshay N

2017-01-01

There is inconclusive evidence about the role of sex as a risk factor for doxorubicin (DOX)-induced cardiotoxicity. Recent experimental studies have shown that adult female rats are protected against DOX-induced cardiotoxicity. However, the mechanisms of this sexual dimorphism are not fully elucidated. We have previously demonstrated that DOX alters the expression of several cytochrome P450 (CYP) enzymes in the hearts of male rats. Nevertheless, the sex-dependent effect of DOX on the expression of CYP enzymes is still not known. Therefore, in the present study, we determined the effect of acute DOX exposure on the expression of CYP genes in the hearts of both male and female C57Bl/6 mice. Acute DOX cardiotoxicity was induced by a single intraperitoneal injection of 20 mg/kg DOX in male and female adult C57Bl/6 mice. Cardiac function was assessed 5 days after DOX exposure by trans-thoracic echocardiography. Mice were euthanized 1 day or 6 days after DOX or saline injection. Thereafter, the hearts were harvested and weighed. Heart sections were evaluated for pathological lesions. Total RNA was extracted and expression of natriuretic peptides, inflammatory and apoptotic markers, and CYP genes was measured by real-time PCR. Adult female C57Bl/6 mice were protected from acute DOX-induced cardiotoxicity as they show milder pathological lesions, less inflammation, and faster recovery from DOX-induced apoptosis and DOX-mediated inhibition of beta-type natriuretic peptide. Acute DOX exposure altered the gene expression of multiple CYP genes in a sex-dependent manner. In 24 h, DOX exposure caused male-specific induction of Cyp1b1 and female-specific induction of Cyp2c29 and Cyp2e1. Acute DOX exposure causes sex-dependent alteration of cardiac CYP gene expression. Since cardiac CYP enzymes metabolize several endogenous compounds to biologically active metabolites, sex-dependent alteration of CYP genes may play a role in the sexual dimorphism of acute DOX-induced cardiotoxicity.

Frequency of cytochrome P450 CYP2C9 variants in a Turkish population and functional relevance for phenytoin

PubMed Central

Sükrü Aynacioglu, A; Brockmöller, Jürgen; Bauer, Steffen; Sachse, Christoph; Güzelbey, Pinar; Öngen, Zuhal; Nacak, Muradiye; Roots, Ivar

1999-01-01

Aims The genetically polymorphic cytochrome P450 enzyme CYP2C9 metabolizes many important drugs. We studied the frequency of the amino acid variants cysteine144 (CYP2C9*2) and leucine359 (CYP2C9*3) in a Turkish population and the correlation between genotype and phenotype using phenytoin as probe drug. Methods CYP2C9 alleles *2 and *3 were measured in 499 unrelated Turkish subjects by PCR and restriction fragment length pattern analysis. Phenotyping was performed in a subgroup of 101 volunteers with a single oral dose of 300 mg phenytoin and concentration analysis in serum drawn 12 h after dosage. Results CYP2C9 allele frequencies in 499 unrelated Turkish subjects were 0.794 for CYP2C9*1, 0.106 for CYP2C9*2 and 0.100 for CYP2C9*3. Mean phenytoin serum concentrations at 12 h after dosage were 4.16 mg l−1 (95% CI 3.86–4.46) in carriers of the genotype CYP2C9*1/1, 5.52 mg l−1 (4.66–6.39) in CYP2C9*1/2, and 5.65 mg l−1 (4.86–6.43) in CYP2C9*1/3. These differences were significant and accounted for 31% of total variability in phenytoin trough levels. Mean 12 h concentration ratios of 5-(para-hydroxyphenyl)-5-phenylhydantoin/phenytoin (p-HPPH/P) were 0.43 (0.39–0.47) for CYP2C9*1/1 compared with 0.26 (0.21–0.31) for CYP2C9*1/2, 0.14 (0.13–0.14) for CYP2C9*2/2, 0.21 (0.18–0.24) for CYP2C9*1/3, and 0.02 for CYP2C9*3/3; all mutant genotypes were significantly different compared with CYP2C9*1/1. Conclusions Frequency of the two CYP2C9 variants in Turkish subjects was in a similar range as in other Caucasian populations. A significant proportion of the interindividual variability in phenytoin trough levels is explained by the genotypes. The 12 h serum concentrations after a single phenytoin dose may be used for routine phenotyping of CYP2C9 mediated metabolic clearance and the p-HPPH/P ratios may be even more sensitive indicators of CYP2C9 activity. PMID:10510154

Two flavonolignans from milk thistle (Silybum marianum) inhibit CYP2C9-mediated warfarin metabolism at clinically achievable concentrations.

PubMed

Brantley, Scott J; Oberlies, Nicholas H; Kroll, David J; Paine, Mary F

2010-03-01

Milk thistle (Silybum marianum) is a popular herbal product used for hepatoprotection and chemoprevention. Two commercially available formulations are the crude extract, silymarin, and the semipurified product, silibinin. Silymarin consists of at least seven flavonolignans, of which the most prevalent are the diastereoisomers silybin A and silybin B; silibinin consists only of silybin A and silybin B. Based on a recent clinical study showing an interaction between a silymarin product and the CYP2C9 substrate losartan, the CYP2C9 inhibition properties of silybin A and silybin B and corresponding regioisomers, isosilybin A and isosilybin B, were evaluated using human liver microsomes (HLMs), recombinant CYP2C9 (rCYP2C9) enzymes, and the clinically relevant probe, (S)-warfarin. Silybin B was the most potent inhibitor in HLMs, followed by silybin A, isosilybin B, and isosilybin A (IC(50) of 8.2, 18, 74, and >100 microM, respectively). Next, silybin A and silybin B were selected for further characterization. As with HLMs, silybin B was more potent than silybin A toward rCYP2C9 1 (6.7 versus 12 microM), rCYP2C9 2 (9.3 versus 19 microM), and rCYP2C9 3 (2.4 versus 9.3 microM). Using a matrix of five substrate (1-15 microM) and six inhibitor (1-80 microM) concentrations and HLMs, both diastereoisomers inhibited (S)-warfarin 7-hydroxylation in a manner described best by a mixed-type inhibition model (K(i) values of 4.8 and 10 microM for silybin B and silybin A, respectively). These observations, combined with the high systemic silibinin concentrations (>5-75 microM) achieved in a phase I study involving prostate cancer patients, prompt clinical evaluation of a potential warfarin-milk thistle interaction.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Arpiainen, Satu; Jaervenpaeae, Sanna-Mari; Manninen, Aki

The nutritional state of organisms and energy balance related diseases such as diabetes regulate the metabolism of xenobiotics such as drugs, toxins and carcinogens. However, the mechanisms behind this regulation are mostly unknown. The xenobiotic-metabolizing cytochrome P450 (CYP) 2A5 enzyme has been shown to be induced by fasting and by glucagon and cyclic AMP (cAMP), which mediate numerous fasting responses. Peroxisome proliferator-activated receptor {gamma} coactivator (PGC)-1{alpha} triggers many of the important hepatic fasting effects in response to elevated cAMP levels. In the present study, we were able to show that cAMP causes a coordinated induction of PGC-1{alpha} and CYP2A5 mRNAsmore » in murine primary hepatocytes. Furthermore, the elevation of the PGC-1{alpha} expression level by adenovirus mediated gene transfer increased CYP2A5 transcription. Co-transfection of Cyp2a5 5' promoter constructs with the PGC-1{alpha} expression vector demonstrated that PGC-1{alpha} is able to activate Cyp2a5 transcription through the hepatocyte nuclear factor (HNF)-4{alpha} response element in the proximal promoter of the Cyp2a5 gene. Chromatin immunoprecipitation assays showed that PGC-1{alpha} binds, together with HNF-4{alpha}, to the same region at the Cyp2a5 proximal promoter. In conclusion, PGC-1{alpha} mediates the expression of CYP2A5 induced by cAMP in mouse hepatocytes through coactivation of transcription factor HNF-4{alpha}. This strongly suggests that PGC-1{alpha} is the major factor mediating the fasting response of CYP2A5.« less

Aryl hydrocarbon receptor activation and CYP1A induction by cooked food-derived carcinogenic heterocyclic amines in human HepG2 cell lines.

PubMed

Sekimoto, Masashi; Sumi, Haruna; Hosaka, Takuomi; Umemura, Takashi; Nishikawa, Akiyoshi; Degawa, Masakuni

2016-11-01

The ability of nine cooked food-derived heterocyclic aromatic amines (HCAs), such as 3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), 3-amino-1-methyl-5H-pyrido[4,3-b]indole (Trp-P-2), 2-amino-6-methylpyrido[12-a:3',2'-d]imidazole (Glu-P-1), 2-amino-pyrido[12-a:3',2'-d]imidazole hydrochloride (Glu-P-2), 2-amino-9H-pyrido[2,3-b]indole (AαC), 2-amino-3-methyl-9H-pyrido[2,3-b]indole (MeAαC), 2-amino-3-methylimidazo[4,5-f]quinolone (IQ), 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) and 2-amino-1-methyl-6-phenyl-1H-imidazo[4,5-b]pyridine (PhIP), to activate human aryl hydrocarbon receptor (hAhR) was examined using a HepG2-A10 cell line, which has previously established from human hepatocarcinoma-derived HepG2 cells for use in hAhR-based luciferase reporter gene assays. Trp-P-1, Trp-P-2, AαC, MeAαC, IQ and MeIQx showed a definite ability to induce not only luciferase (hAhR activation) in HepG2-A10 cells but also cytochrome P450 (CYP)1A1/1A2 mRNAs in HepG2 cells, while such the ability of Glu-P-1, Glu-P-2, and PhIP was very low. In addition, all the HCAs examined, especially MeAαC and MeIQx, had a definite capacity for inhibiting the activity of ethoxyresorfin O-deethylase (CYP1As, especially CYP1A1). The present findings demonstrate that all the HCAs examined have the ability to activate hAhR and its target genes, and further confirm that these HCAs become good substrates for human CYP1A subfamily enzyme(s). Copyright © 2016 Elsevier Ltd. All rights reserved.

Effect of P450 Oxidoreductase Polymorphisms on the Metabolic Activities of Ten Cytochrome P450s Varied by Polymorphic CYP Genotypes in Human Liver Microsomes.

PubMed

Fang, Yan; Gao, Na; Tian, Xin; Zhou, Jun; Zhang, Hai-Feng; Gao, Jie; He, Xiao-Pei; Wen, Qiang; Jia, Lin-Jing; Jin, Han; Qiao, Hai-Ling

2018-06-27

Background/ Aims: Little is known about the effect of P450 oxidoreductase (POR) gene polymorphisms on the activities of CYPs with multiple genotypes. We genotyped 102 human livers for 18 known POR single nucleotide polymorphisms (SNPs) with allelic frequencies greater than 1% as well as for 27 known SNPs in 10 CYPs. CYP enzyme activities in microsomes prepared from these livers were determined by measuring probe substrate metabolism by high performance liquid chromatograph. We found that the effects of the 18 POR SNPs on 10 CYP activities were CYP genotype-dependent. The POR mutations were significantly associated with decreased overall Km for CYP2B6 and 2E1, and specific genotypes within CYP1A2, 2A6, 2B6, 2C8, 2D6 and 2E1 were identified as being affected by these POR SNPs. Notably, the effect of a specific POR mutation on the activity of a CYP genotype could not be predicted from other CYP genotypes of even the same CYP. When combining one POR SNP with other POR SNPs, a hitherto unrecognized effect of multiple-site POR gene polymorphisms (MSGP) on CYP activity was uncovered, which was not necessarily consistent with the effect of either single POR SNP. The effects of POR SNPs on CYP activities were not only CYP-dependent, but more importantly, CYP genotype-dependent. Moreover, the effect of a POR SNP alone and in combination with other POR SNPs (MSGP) was not always consistent, nor predictable. Understanding the impact of POR gene polymorphisms on drug metabolism necessitates knowing the complete SNP complement of POR and the genotype of the relevant CYPs. © 2018 The Author(s). Published by S. Karger AG, Basel.

Development of Murine Cyp3a Knockout Chimeric Mice with Humanized Liver.

PubMed

Kato, Kota; Ohbuchi, Masato; Hamamura, Satoko; Ohshita, Hiroki; Kazuki, Yasuhiro; Oshimura, Mitsuo; Sato, Koya; Nakada, Naoyuki; Kawamura, Akio; Usui, Takashi; Kamimura, Hidetaka; Tateno, Chise

2015-08-01

We developed murine CYP3A knockout ko chimeric mice with humanized liver expressing human P450S similar to those in humans and whose livers and small intestines do not express murine CYP3A this: approach may overcome effects of residual mouse metabolic enzymes like Cyp3a in conventional chimeric mice with humanized liver, such as PXB-mice [urokinase plasminogen activator/severe combined immunodeficiency (uPA/SCID) mice repopulated with over 70% human hepatocytes] to improve the prediction of drug metabolism and pharmacokinetics in humans. After human hepatocytes were transplanted into Cyp3a KO/uPA/SCID host mice, human albumin levels logarithmically increased until approximately 60 days after transplantation, findings similar to those in PXB-mice. Quantitative real-time-polymerase chain reaction analyses showed that hepatic human P450s, UGTs, SULTs, and transporters mRNA expression levels in Cyp3a KO chimeric mice were also similar to those in PXB-mice and confirmed the absence of Cyp3a11 mRNA expression in mouse liver and intestine. Findings for midazolam and triazolam metabolic activities in liver microsomes were comparable between Cyp3a KO chimeric mice and PXB-mice. In contrast, these activities in the intestine of Cyp3a KO chimeric mice were attenuated compared with PXB-mice. Owing to the knockout of murine Cyp3a, hepatic Cyp2b10 and 2c55 mRNA levels in Cyp3a KO/uPA/SCID mice (without hepatocyte transplants) were 8.4- and 61-fold upregulated compared with PXB-mice, respectively. However, human hepatocyte transplantation successfully restored Cyp2b10 level nearly fully and Cyp2c55 level partly (still 13-fold upregulated) compared with those in PXB-mice. Intestinal Cyp2b10 and 2c55 were also repressed by human hepatocyte transplantation in Cyp3a KO chimeric mice. Copyright © 2015 by The American Society for Pharmacology and Experimental Therapeutics.

The effect of chlorpyrifos-oxon and other xenobiotics on the human cytochrome P450-dependent metabolism of naphthalene and deet.

PubMed

Cho, Taehyeon M; Rose, Randy L; Hodgson, Ernest

2007-01-01

Chlorpyrifos-oxon (CPO), a metabolite of chlorpyrifos, is a potent inhibitor of acetylcholinesterase and, although the neurotoxicological impact of this organophosphorus compound has been broadly studied both in vitro and in vivo, there are few studies of metabolic interactions of CPO with other xenobiotics. CPO significantly activated the production of 1-naphthol (5-fold), 2-naphthol (10-fold), trans-1,2-dihydro-1,2-naphthalenediol (1.5-fold), and 1,4-naphthoquinone from naphthalene by human liver microsomes (HLM). It was further demonstrated that the production of naphthalene metabolites by CYP2C8, 2C9*(1), 2C19, 2D6*(1), 3A4, 3A5, and 3A7 was activated by CPO, while the production of naphthalene metabolites by CYP1A1, 1A2, 1B1, and 2B6 was inhibited by CPO. CPO inhibited CYP1A2 production of naphthalene metabolites, while activating their production by CYP3A4. Similarly, CPO inhibited the production of N,N-diethyl-m-hydroxymethylbenzamide (BALC) from DEET by human liver microsomes, but activated the production of N-ethyl-m-toluamide (ET) from this substrate. CYP2B6, the most efficient isoform for BALC production, was inhibited by CPO, while CYP3A4, the most efficient isoform for ET production, was activated by CPO. CPO inhibited CYP2B6 production of both BALC and ET from DEET, but activated CYP3A4 production of ET, while inhibiting CYP3A4 BALC production. CPO appears to facilitate the binding of naphthalene to CYP3A4. This metabolic activation is independent of cytochrome b5, suggesting that activation of CYP3A4 by CPO is associated with a conformational change of the isoform rather than facilitating electron transfer.

Genetic variations of VDR/NR1I1 encoding vitamin D receptor in a Japanese population.

PubMed

Ukaji, Maho; Saito, Yoshiro; Fukushima-Uesaka, Hiromi; Maekawa, Keiko; Katori, Noriko; Kaniwa, Nahoko; Yoshida, Teruhiko; Nokihara, Hiroshi; Sekine, Ikuo; Kunitoh, Hideo; Ohe, Yuichiro; Yamamoto, Noboru; Tamura, Tomohide; Saijo, Nagahiro; Sawada, Jun-ichi

2007-12-01

The vitamin D receptor (VDR) is a transcriptional factor responsive to 1alpha,25-dihydroxyvitamin D(3) and lithocholic acid, and induces expression of drug metabolizing enzymes CYP3A4, CYP2B6 and CYP2C9. In this study, the promoter regions, 14 exons (including 6 exon 1's) and their flanking introns of VDR were comprehensively screened for genetic variations in 107 Japanese subjects. Sixty-one genetic variations including 25 novel ones were found: 9 in the 5'-flanking region, 2 in the 5'-untranslated region (UTR), 7 in the coding exons (5 synonymous and 2 nonsynonymous variations), 12 in the 3'-UTR, 19 in the introns between the exon 1's, and 12 in introns 2 to 8. Of these, one novel nonsynonymous variation, 154A>G (Met52Val), was detected with an allele frequency of 0.005. The single nucleotide polymorphisms (SNPs) that increase VDR expression or activity, -29649G>A, 2T>C and 1592((*)308)C>A tagging linked variations in the 3'-UTR, were detected at 0.430, 0.636, and 0.318 allele frequencies, respectively. Another SNP, -26930A>G, with reduced VDR transcription was found at a 0.028 frequency. These findings would be useful for association studies on VDR variations in Japanese.

Clopidogrel and proton pump inhibitor (PPI) interaction: separate intake and a non-omeprazole PPI the solution?

PubMed Central

2010-01-01

Background Dual therapy with aspirin and clopidogrel increases the risk of gastrointestinal bleeding. Therefore, co-therapy with a proton pump inhibitor (PPI) is recommended by most guidelines. However, there are warnings against combining PPIs with clopidogrel because of their interactions with cytochrome P450 isoenzyme 2C19 (CYP2C19). Methods The effects of the combined or separate intake of 20 mg of omeprazole and 75 mg of clopidogrel on the clopidogrel-induced inhibition of platelet aggregation were measured in four healthy subjects whose CYP2C19 exon sequences were determined. The effects of co-therapy with 10 mg of rabeprazole were also examined. Results Two subjects showed the wild-type CYP2C19 sequence. The concurrent intake of omeprazole had no effect on clopidogrel-induced platelet inhibition in these subjects. Two subjects were heterozygous for the *2 allele, with predicted reduced CYP2C19 activity. One of them was a clopidogrel non-responder. In the second heterozygous subject, omeprazole co-therapy reduced the clopidogrel anti-platelet effect when taken simultaneously or separately. However, the simultaneous intake of rabeprazole did not reduce the clopidogrel effect. Conclusion The clopidogrel-PPI interaction does not seem to be a PPI class effect. Rabeprazole did not affect the clopidogrel effect in a subject with a clear omeprazole-clopidogrel interaction. The separate intake of PPI and clopidogrel may not be sufficient to prevent their interaction. PMID:20562062

Human cytochrome P450 isozymes in metabolism and health effects of gasoline ethers.

PubMed

Hong, J Y; Wang, Y Y; Mohr, S N; Bondoc, F Y; Deng, C

2001-05-01

To reduce the production of carbon monoxide and other pollutants in motor vehicle exhaust, methyl tert-butyl ether (MTBE*), ethyl tert-butyl ether (ETBE), and tert-amyl methyl ether (TAME) are added to gasoline as oxygenates for more complete combustion. Among them, MTBE is the most widely used. The possible adverse effect of MTBE in humans is a public concern, but the human enzymes responsible for metabolism of these gasoline ethers and the causes or factors for increased sensitivity to MTBE in certain individuals are totally unknown. This information is important to understanding the health effects of MTBE in humans and to assessing the human relevance of pharmacokinetics and toxicity data obtained from animals. In the present study, we demonstrated that human liver is active in metabolizing MTBE to tert-butyl alcohol (TBA), a major circulating metabolite and an exposure marker of MTBE. The activity is localized in the microsomal fraction but not in the cytosol. Formation of TBA in human liver microsomes is NADPH-dependent and is significantly inhibited by carbon monoxide, which inhibits cytochrome P450 (CYP) enzymes. These results provide strong evidence that CYP enzymes play a critical role in the metabolism of MTBE in human livers. Human liver is also active in the oxidative metabolism of 2 other gasoline ethers, ETBE and TAME. We observed a large interindividual variation in metabolizing these gasoline ethers in 15 microsomal samples prepared from normal human livers. The activity level (pmol metabolite/min/mg) ranged from 204 to 2,890 for MTBE; 179 to 3,134 for ETBE; and 271 to 8,532 for TAME. The microsomal activities in metabolizing MTBE, ETBE, and TAME correlated highly with each other (r = 0.91 to 0.96), suggesting that these ethers are metabolized by the same enzyme(s). Correlation analysis of the ether-metabolizing activities with individual CYP enzyme activities in the human liver microsomes showed that the highest degree of correlation was with CYP isoform 2A6 (CYP2A6)+ (r = 0.94 for MTBE, 0.95 for ETBE, and 0.90 for TAME), which is constitutively expressed in human livers and known to be polymorphic. CYP2A6 displayed the highest turnover number in metabolizing gasoline ethers among a battery of human CYP enzymes expressed in human B-lymphoblastoid cells. CYP2A6 coexpressed with human CYP reductase by a baculovirus expression system was also more active than CYP isoform 2E1 (CYP2E1) in the metabolism of MTBE, ETBE, and TAME. Kinetic studies on MTBE metabolism with human liver microsomes (n = 3) exhibited an apparent Michaelis constant (Km) of 28 to 89 microM and a maximum rate of metabolism (Vmax) of 215 to 783 pmol/min/mg. Metabolism of MTBE, ETBE, and TAME by human liver microsomes was inhibited by coumarin, a known substrate of human CYP2A6, in a concentration-dependent manner. Monoclonal antibody against human CYP2A6 caused a significant inhibition (75% to 95%) of the metabolism of MTBE, ETBE, and TAME in human liver microsomes. Taken together, these results clearly indicate that, in human liver, CYP2A6 is a major enzyme responsible for metabolism of MTBE, ETBE, and TAME. Although CYP2E1 metabolizes diethyl ether and was previously suggested to be involved

Twice-daily dosing of esomeprazole effectively inhibits acid secretion in CYP2C19 rapid metabolisers compared with twice-daily omeprazole, rabeprazole or lansoprazole.

PubMed

Sahara, S; Sugimoto, M; Uotani, T; Ichikawa, H; Yamade, M; Iwaizumi, M; Yamada, T; Osawa, S; Sugimoto, K; Umemura, K; Miyajima, H; Furuta, T

2013-11-01

Twice-daily dosing of proton pump inhibitors (PPIs) is used to treat Helicobacter pylori or acid-related diseases, such as gastro-oesophageal reflux disease (GERD) refractory to standard dose of a PPI. Genetic polymorphisms of CYP2C19 are involved to different extents in the metabolism of four kinds of PPIs (omeprazole, lansoprazole, rabeprazole and esomeprazole) available in Japan. To compare acid-inhibitory effects of the four PPIs dosed twice daily in relation to CYP2C19 genotype. We performed 24-h pH monitoring studies on Day 7 of PPI treatment for 40 Japanese H. pylori-negative volunteers [15 CYP2C19 rapid metabolisers (RMs), 15 intermediate metabolisers (IMs) and 10 poor metabolisers (PMs)] using a randomised four-way crossover design: omeprazole 20 mg, esomeprazole 20 mg, lansoprazole 30 mg and rabeprazole 10 mg twice daily. Although median pH values with esomeprazole, omeprazole, lansoprazole and rabeprazole were 5.7 (3.5-7.2), 5.5 (2.4-7.2), 5.5 (3.7-7.3) and 5.2 (2.5-7.3), respectively (no statistically significant differences), CYP2C19 genotype-dependent differences were smaller for esomeprazole and rabeprazole compared with values for omeprazole and lansoprazole. In CYP2C19 RMs, the median pH with esomeprazole [5.4 (3.5-6.8)] was significantly higher than those with omeprazole [5.0 (2.4-5.9), P = 0.018], lansoprazole [4.7 (3.7-5.5), P = 0.017] or rabeprazole [4.8 (2.5-6.4), P = 0.002]. In IMs and PMs, the median pH was >5.0 independent of the PPI. In intermediate and rapid metabolisers of CYP2C19, PPIs dosed twice daily could attain sufficient acid suppression, while in CYP2C19 RMs, esomeprazole 20 mg twice daily caused the strongest inhibition of the four PPIs. Therefore, esomeprazole may be effective in Japanese population when dosed twice daily. © 2013 John Wiley & Sons Ltd.

Implications of intercorrelation between hepatic CYP3A4-CYP2C8 enzymes for the evaluation of drug-drug interactions: a case study with repaglinide.

PubMed

Doki, Kosuke; Darwich, Adam S; Achour, Brahim; Tornio, Aleksi; Backman, Janne T; Rostami-Hodjegan, Amin

2018-05-01

Statistically significant positive correlations are reported for the abundance of hepatic drug-metabolizing enzymes. We investigate, as an example, the impact of CYP3A4-CYP2C8 intercorrelation on the predicted interindividual variabilities of clearance and drug-drug interactions (DDIs) for repaglinide using physiologically based pharmacokinetic (PBPK) modelling. PBPK modelling and simulation were employed using Simcyp Simulator (v15.1). Virtual populations were generated assuming intercorrelations between hepatic CYP3A4-CYP2C8 abundances derived from observed values in 24 human livers. A repaglinide PBPK model was used to predict PK parameters in the presence and absence of gemfibrozil in virtual populations, and the results were compared with a clinical DDI study. Coefficient of variation (CV) of oral clearance was 52.5% in the absence of intercorrelation between CYP3A4-CYP2C8 abundances, which increased to 54.2% when incorporating intercorrelation. In contrast, CV for predicted DDI (as measured by AUC ratio before and after inhibition) was reduced from 46.0% in the absence of intercorrelation between enzymes to 43.8% when incorporating intercorrelation: these CVs were associated with 5th/95th percentiles (2.48-11.29 vs. 2.49-9.69). The range of predicted DDI was larger in the absence of intercorrelation (1.55-77.06) than when incorporating intercorrelation (1.79-25.15), which was closer to clinical observations (2.6-12). The present study demonstrates via a systematic investigation that population-based PBPK modelling incorporating intercorrelation led to more consistent estimation of extreme values than those observed in interindividual variabilities of clearance and DDI. As the intercorrelations more realistically reflect enzyme abundances, virtual population studies involving PBPK and DDI should avoid using Monte Carlo assignment of enzyme abundance. © 2018 The British Pharmacological Society.

The participation of human hepatic P450 isoforms, flavin-containing monooxygenases and aldehyde oxidase in the biotransformation of the insecticide fenthion

DOE Office of Scientific and Technical Information (OSTI.GOV)

Leoni, Claudia; Buratti, Franca M.; Testai, Emanuela

Although fenthion (FEN) is widely used as a broad spectrum insecticide on various crops in many countries, very scant data are available on its biotransformation in humans. In this study the in vitro human hepatic FEN biotransformation was characterized, identifying the relative contributions of cytochrome P450 (CYPs) and/or flavin-containing monooxygenase (FMOs) by using single c-DNA expressed human enzymes, human liver microsomes and cytosol and CYP/FMO-specific inhibitors. Two major metabolites, FEN-sulfoxide and FEN-oxon (FOX), are formed by some CYPs although at very different levels, depending on the relative CYP hepatic content. Formation of further oxidation products and the reduction of FEN-sulfoxidemore » back to FEN by the cytosolic aldehyde oxidase enzyme were ruled out. Comparing intrinsic clearance values, FOX formation seemed to be favored and at low FEN concentrations CYP2B6 and 1A2 are mainly involved in its formation. At higher levels, a more widespread CYP involvement was evident, as in the case of FEN-sulfoxide, although a higher efficiency of CYP2C family was suggested. Hepatic FMOs were able to catalyze only sulfoxide formation, but at low FEN concentrations hepatic FEN sulfoxidation is predominantly P450-driven. Indeed, the contribution of the hepatic isoforms FMO{sub 3} and FMO{sub 5} was generally negligible, although at high FEN concentrations FMO's showed activities comparable to the active CYPs, accounting for up to 30% of total sulfoxidation. Recombinant FMO{sub 1} showed the highest efficiency with respect to CYPs and the other FMOs, but it is not expressed in the adult human liver. This suggests that FMO{sub 1}-catalysed sulfoxidation may represent the major extra-hepatic pathway of FEN biotransformation.« less

Xenobiotic Metabolizing Enzyme and Transporter Gene Expression in Primary Cultures of Human Hepatocytes Modulated by ToxCast Chemicals

EPA Science Inventory

ToxCast chemicals were assessed for induction or suppression of xenobiotic metabolizing enzyme and transporter gene expression using primary human hepatocytes. The mRNA levels of 14 target and 2 control genes were measured: ABCB1, ABCB11, ABCG2, SLCO1B1, CYP1A1, CYP1A2, CYP2B6, C...

Metabolism of myclobutanil and triadimefon by human and rat cytochrome P450 enzymes and liver microsomes.

PubMed

Barton, H A; Tang, J; Sey, Y M; Stanko, J P; Murrell, R N; Rockett, J C; Dix, D J

2006-09-01

Metabolism of two triazole-containing antifungal azoles was studied using expressed human and rat cytochrome P450s (CYP) and liver microsomes. Substrate depletion methods were used due to the complex array of metabolites produced from myclobutanil and triadimefon. Myclobutanil was metabolized more rapidly than triadimefon, which is consistent with metabolism of the n-butyl side-chain in the former and the t-butyl group in the latter compound. Human and rat CYP2C and CYP3A enzymes were the most active. Metabolism was similar in microsomes prepared from livers of control and low-dose rats. High-dose (115 mg kg-1 day-1 of triadimefon or 150 mg kg-1 day-1 of myclobutanil) rats showed increased liver weight, induction of total CYP, and increased metabolism of the two triazoles, though the apparent Km appeared unchanged relative to the control. These data identify CYP enzymes important for the metabolization of these two triazoles. Estimated hepatic clearances suggest that CYP induction may have limited impact in vivo.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Levova, Katerina; Moserova, Michaela; Nebert, Daniel W.

Aristolochic acid causes a specific nephropathy (AAN), Balkan endemic nephropathy, and urothelial malignancies. Using Western blotting suitable to determine protein expression, we investigated in several transgenic mouse lines expression of NAD(P)H:quinone oxidoreductase (NQO1)—the most efficient cytosolic enzyme that reductively activates aristolochic acid I (AAI). The mouse tissues used were from previous studies [Arlt et al., Chem. Res. Toxicol. 24 (2011) 1710; Stiborova et al., Toxicol. Sci. 125 (2012) 345], in which the role of microsomal cytochrome P450 (CYP) enzymes in AAI metabolism in vivo had been determined. We found that NQO1 levels in liver, kidney and lung of Cyp1a1(−/−), Cyp1a2(−/−)more » and Cyp1a1/1a2(−/−) knockout mouse lines, as well as in two CYP1A-humanized mouse lines harboring functional human CYP1A1 and CYP1A2 and lacking the mouse Cyp1a1/1a2 orthologs, differed from NQO1 levels in wild-type mice. NQO1 protein and enzymic activity were induced in hepatic and renal cytosolic fractions isolated from AAI-pretreated mice, compared with those in untreated mice. Furthermore, this increase in hepatic NQO1 enzyme activity was associated with bioactivation of AAI and elevated AAI-DNA adduct levels in ex vivo incubations of cytosolic fractions with DNA and AAI. In conclusion, AAI appears to increase its own metabolic activation by inducing NQO1, thereby enhancing its own genotoxic potential. Highlights: ► NAD(P)H:quinone oxidoreductase expression in Cyp1a knockout and humanized CYP1A mice ► Reductive activation of the nephrotoxic and carcinogenic aristolochic acid I (AAI) ► NAD(P)H:quinone oxidoreductase is induced in mice treated with AAI. ► Induced hepatic enzyme activity resulted in elevated AAI-DNA adduct levels.« less

Cytochrome P450 genes from the aquatic midge Chironomus tentans: Atrazine-induced up-regulation of CtCYP6EX3 enhanced the toxicity of chlorpyrifos.

PubMed

Tang, Guanghui; Yao, Jianxiu; Li, Daqi; He, Yanping; Zhu, Yu-Cheng; Zhang, Xin; Zhu, Kun Yan

2017-11-01

The open reading frames of 19 cytochrome P450 monooxygenase (CYP) genes were sequenced from Chironomus tentans, a commonly used freshwater invertebrate model. Phylogenetic analysis of the 19 CYPs along with a previously reported CYP (CtCYP4G33) revealed that they belong to three different clans, including 3 in CYP4, 15 in CYP3, and 2 in mitochondria clan. When third-instar larvae were exposed to atrazine at 5000 μg/L, the transcription of CtCYP6EX3, CtCYP6EV3, CtCYP9AT1 and CtCYPEX1 was significantly up-regulated. To examine whether CtCYP6EX3 played a role in oxidative activation of chlorpyrifos to chlorpyrifos-oxon, we evaluated larval susceptibility to chlorpyrifos after CtCYP6EX3 transcript was suppressed by RNAi. The larvae fed chitosan/dsCtCYP6EX3 nanoparticles showed a significantly decreased CtCYP6EX3 transcript (53.1%) as compared with the control larvae fed chitosan/dsGFP nanoparticles. When the CtCYP6EX3-silenced larvae were exposed to chlorpyrifos at 6 μg/L or its binary mixture with atrazine (chlorpyrifos at 3 μg/L and atrazine at 1000 μg/L), the larvae became less susceptible to the pesticides as their mortalities decreased by 24.1% and 20.5%, respectively. These results along with our previous findings suggested that the increased toxicity of chlorpyrifos was likely due to an enhanced oxidative process from chlorpyrifos to chlorpyrifos-oxon by CtCYP6EX3 as RNAi of CtCYP6EX3 led to decreased susceptibility of C. tentans larvae to chlorpyrifos alone and the binary mixture of atrazine and chlorpyrifos. However, further study would be necessary to validate our results by functional assays using heterologously expressed CtCYP6EX3 enzyme. Copyright © 2017 Elsevier Ltd. All rights reserved.

Characterization and profiling of hepatic cytochromes P450 and phase II xenobiotic-metabolizing enzymes in beluga whales (Delphinapterus leucas) from the St. Lawrence River Estuary and the Canadian Arctic.

PubMed

McKinney, Melissa A; Arukwe, Augustine; De Guise, Sylvain; Martineau, Daniel; Béland, Pierre; Dallaire, André; Lair, Stéphane; Lebeuf, Michel; Letcher, Robert J

2004-07-30

Cytochromes P450 (CYP, phase I) and conjugating (phase II) enzymes can be induced by and influence the toxicokinetics (metabolism) and toxicity of xenobiotic contaminants in exposed organisms. Beluga whale (Delphinapterus leucas) from the endangered St. Lawrence (SL) River Estuary population exhibit deleterious health effects and various severe pathologies that have been associated with contaminant exposure. In contrast, such effects (e.g. reproductive and immunological impairment) are generally less frequent in less exposed populations in the Canadian Arctic (CA). In the present study, opportunistic sampling resulted in the collection immediately after death of liver tissue from a single female neonate SL beluga (SL6) and male and female CA beluga (n=10) from the Arviat region of western Hudson Bay, in addition to sampling of stranded carcasses of male and female SL beluga (n=5) at least 12 h postmortem. We immunologically characterized cross-reactive proteins of hepatic microsomal CYP1A, CYP2B, CYP3A, CYP2E, epoxide hydrolase (EH) and uridine diphosphoglucuronosyl transferase (UDPGT) isozymes. Cross-reactive proteins were found in all SL and CA beluga using anti-rat CYP1A1, anti-rainbow trout CYP3A, anti-human CYP2E1, anti-rabbit EH and anti-human UDPGT1A1 polyclonal antibodies (Abs), whereas faintly cross-reactive CYP2B proteins were only found in SL6 and the CA samples using an anti-rabbit CYP2B1 Ab. In corresponding catalytic activity assessments, only SL6 and all CA beluga microsomal samples exhibited CYP1A-mediated 7-ethoxyresorufin O-deethylase (EROD) activity (51-260 pmol/mg/min), CYP3A-mediated activity (113-899 pmol/mg/min) based on the formation of 6beta-hydroxytestosterone using a testosterone hydroxylase assay, and UDPGT activity (830-4956 pmol/mg/min) based on 1-naphthylglucuronide formation. The marginal cross-reactivity with the anti-CYP2B1 Ab and lack of catalytically measurable hydroxytestosterone isomers associated with CYP2B-type activity in all the SL and CA animals is suggestive of low CYP2B-type enzyme expression in beluga. The absence of measurable total P450 enzyme levels and catalytic activities in samples from the stranded SL belugas suggested catalytically inactive enzymes as a consequence of tissue degradation related due to the time delay of sample collection after death. However, all SL and CA animals demonstrated similar, immunologically cross-reactive phase I and II hepatic enzyme profiles, which is suggestive of the importance of metabolism in the toxicokinetics and fate of xenobiotics in animals from both populations Copyright 2004 Elsevier B.V.

Pyrethroid insecticide lambda-cyhalothrin induces hepatic cytochrome P450 enzymes, oxidative stress and apoptosis in rats.

PubMed

Martínez, María-Aránzazu; Ares, Irma; Rodríguez, José-Luis; Martínez, Marta; Roura-Martínez, David; Castellano, Victor; Lopez-Torres, Bernardo; Martínez-Larrañaga, María-Rosa; Anadón, Arturo

2018-08-01

This study aimed to examine in rats the effects of the Type II pyrethroid lambda-cyhalothrin on hepatic microsomal cytochrome P450 (CYP) isoform activities, oxidative stress markers, gene expression of proinflammatory, oxidative stress and apoptosis mediators, and CYP isoform gene expression and metabolism phase I enzyme PCR array analysis. Lambda-cyhalothrin, at oral doses of 1, 2, 4 and 8mg/kg bw for 6days, increased, in a dose-dependent manner, hepatic activities of ethoxyresorufin O-deethylase (CYP1A1), methoxyresorufin O-demethylase (CYP1A2), pentoxyresorufin O-depentylase (CYP2B1/2), testosterone 7α- (CYP2A1), 16β- (CYP2B1), and 6β-hydroxylase (CYP3A1/2), and lauric acid 11- and 12-hydroxylase (CYP4A1/2). Similarly, lambda-cyhalothrin (4 and 8mg/kg bw, for 6days), in a dose-dependent manner, increased significantly hepatic CYP1A1, 1A2, 2A1, 2B1, 2B2, 2E1, 3A1, 3A2 and 4A1 mRNA levels and IL-1β, NFκB, Nrf2, p53, caspase-3 and Bax gene expressions. PCR array analysis showed from 84 genes examined (P<0.05; fold change>1.5), changes in mRNA levels in 18 genes: 13 up-regulated and 5 down-regulated. A greater fold change reversion than 3-fold was observed on the up-regulated ALDH1A1, CYP2B2, CYP2C80 and CYP2D4 genes. Ingenuity Pathway Analysis (IPA) groups the expressed genes into biological mechanisms that are mainly related to drug metabolism. In the top canonical pathways, Oxidative ethanol degradation III together with Fatty Acid α-oxidation may be significant pathways for lambda-cyhalothrin. Our results may provide further understanding of molecular aspects involved in lambda-cyhalothrin-induced liver injury. Copyright © 2018. Published by Elsevier B.V.

Structure and function of CYP108D1 from Novosphingobium aromaticivorans DSM12444: an aromatic hydrocarbon-binding P450 enzyme.

PubMed

Bell, Stephen G; Yang, Wen; Yorke, Jake A; Zhou, Weihong; Wang, Hui; Harmer, Jeffrey; Copley, Rachel; Zhang, Aili; Zhou, Ruimin; Bartlam, Mark; Rao, Zihe; Wong, Luet Lok

2012-03-01

CYP108D1 from Novosphingobium aromaticivorans DSM12444 binds a range of aromatic hydrocarbons such as phenanthrene, biphenyl and phenylcyclohexane. Its structure, which is reported here at 2.2 Å resolution, is closely related to that of CYP108A1 (P450terp), an α-terpineol-oxidizing enzyme. The compositions and structures of the active sites of these two enzymes are very similar; the most significant changes are the replacement of Glu77 and Thr103 in CYP108A1 by Thr79 and Val105 in CYP108D1. Other residue differences lead to a larger and more hydrophobic access channel in CYP108D1. These structural features are likely to account for the weaker α-terpineol binding by CYP108D1 and, when combined with the presence of three hydrophobic phenylalanine residues in the active site, promote the binding of aromatic hydrocarbons. The haem-proximal surface of CYP108D1 shows a different charge distribution and topology to those of CYP101D1, CYP101A1 and CYP108A1, including a pronounced kink in the proximal loop of CYP108D1, which may result in poor complementarity with the [2Fe-2S] ferredoxins Arx, putidaredoxin and terpredoxin that are the respective redox partners of these three P450 enzymes. The unexpectedly low reduction potential of phenylcyclohexane-bound CYP108D1 (-401 mV) may also contribute to the low activity observed with these ferredoxins. CYP108D1 appears to function as an aromatic hydrocarbon hydroxylase that requires a different electron-transfer cofactor protein.

Reduced-Function CYP2C19 Genotype and Risk of Adverse Clinical Outcomes Among Patients Treated With Clopidogrel Predominantly for PCI: A Meta-Analysis

PubMed Central

Mega, Jessica L.; Simon, Tabassome; Collet, Jean-Philippe; Anderson, Jeffrey L.; Antman, Elliott M.; Bliden, Kevin; Cannon, Christopher P.; Danchin, Nicolas; Giusti, Betti; Gurbel, Paul; Horne, Benjamin D.; Hulot, Jean-Sebastian; Kastrati, Adnan; Montalescot, Gilles; Neumann, Franz-Josef; Shen, Lei; Sibbing, Dirk; Steg, P. Gabriel; Trenk, Dietmar; Wiviott, Stephen D.; Sabatine, Marc S.

2011-01-01

Content Clopidogrel, one of the most commonly prescribed medications, is a pro-drug requiring CYP450 biotransformation. Data suggest its pharmacologic effect varies based on CYP2C19 genotype, but there is uncertainty regarding the clinical risk imparted by specific genotypes. Objective In patients treated with clopidogrel, to define the risk of major adverse cardiovascular outcomes among carriers of one (∼26% prevalence in whites) and carriers of two (∼2% prevalence in whites) reduced-function CYP2C19 variants. Data Sources and Study Selection A literature search was conducted (January 2000-August 2010) of the MEDLINE, Cochrane, and EMBASE databases. Genetic studies were included where clopidogrel was initiated in predominantly invasively managed patients in a manner consistent with the current guideline recommendations and where clinical outcomes were ascertained. Data Extraction Investigators from nine studies evaluating CYP2C19 genotype and clinical outcomes in patients treated with clopidogrel contributed the relevant hazard ratios (HRs) and their 95% confidence intervals (CI) for specific cardiovascular outcomes by genotype. Results Among 9685 patients [91.3% of whom underwent percutaneous coronary intervention (PCI) and 54.5% of whom had an acute coronary syndrome (ACS)], 863 experienced the composite endpoint of cardiovascular death, myocardial infarction, or stroke; 84 patients had stent thrombosis among the 5894 evaluated for such. Overall, 71.5% were non-carriers, 26.3% had one, and 2.2% had two CYP2C19 reduced-function alleles. A significantly increased risk of the composite endpoint was evident in both carriers of one (HR 1.55, 95% CI 1.11-2.27, P=0.01) and two (HR 1.76, 95% CI 1.24-2.50, P=0.002) CYP2C19 reduced-function alleles. Similarly, there was a significantly increased risk of stent thrombosis in both carriers of one (HR 2.67, 95% CI 1.69-4.22, P<0.0001) and two (HR 3.97, 95% CI 1.75-9.02, P=0.001) CYP2C19 reduced-function alleles. Conclusion Among patients treated with clopidogrel for PCI, carriage of even one reduced-function CYP2C19 allele appears to be associated with a significantly increased risk of major adverse cardiovascular events, particularly stent thrombosis. PMID:20978260

[The metabolic fingerprint of the compatibility of Radix Aconite and Radix Paeoniae Alba and its effect on CYP450 enzymes].

PubMed

Bi, Yun-Feng; Zheng, Zhong; Pi, Zi-Feng; Liu, Zhi-Qiang; Song, Feng-Rui

2014-12-01

Using a UPLC-MS/MS (MRM) and cocktail probe substrates method, the metabolic fingerprint of the compatibility of Radix Aconite (RA) and Radix Paeoniae Alba (RPA) and its effect on CYP450 enzymes were investigated. These main CYP isoforms include CYP 1A2, CYP 2C, CYP 2E1, CYP 2D and CYP 3A. Compared with the inhibition effect of RA decoctions on CYP450 isoforms, their co-decoctions of RA and RPA with different proportions can decrease RA' inhibition on CYP3A, CYP2D, CYP2C and CYP1A2, but can not reduce RA' effect on CYP2E1. The metabolic fingerprints of RA decoction and co-decoctions with different proportions of RPA in CYP450 of rat liver were analyzed by UPLC-MS. Compared with the metabolic fingerprints of RA decoction, the intensity of diester-diterpenoid aconitum alkaloids decreased significantly, while the intensity of monoester-diterpenoid alkaloids significantly increased in the metabolic fingerprints of co-decoctions of RA and RPA. The results suggest that RA coadministration with RPA increased the degradation of toxic alkaloid and show the effect of toxicity reducing and efficacy enhancing.

Natural variations in xenobiotic-metabolizing enzymes: developing tools for coral monitoring

NASA Astrophysics Data System (ADS)

Rougée, L. R. A.; Richmond, R. H.; Collier, A. C.

2014-06-01

The continued deterioration of coral reefs worldwide demonstrates the need to develop diagnostic tools for corals that go beyond general ecological monitoring and can identify specific stressors at sublethal levels. Cellular diagnostics present an approach to defining indicators (biomarkers) that have the potential to reflect the impact of stress at the cellular level, allowing for the detection of intracellular changes in corals prior to outright mortality. Detoxification enzymes, which may be readily induced or inhibited by environmental stressors, present such a set of indicators. However, in order to apply these diagnostic tools for the detection of stress, a detailed understanding of their normal, homeostatic levels within healthy corals must first be established. Herein, we present molecular and biochemical evidence for the expression and activity of major Phase I detoxification enzymes cytochrome P450 (CYP450), CYP2E1, and CYP450 reductase, as well as the Phase II enzymes UDP, glucuronosyltransferase (UGT), β-glucuronidase, glutathione- S-transferase (GST), and arylsulfatase C (ASC) in the coral Pocillopora damicornis. Additionally, we characterized enzyme expression and activity variations over a reproductive cycle within a coral's life history to determine natural endogenous changes devoid of stress exposure. Significant changes in enzyme activity over the coral's natural lunar reproductive cycle were observed for CYP2E1 and CYP450 reductase as well as UGT and GST, while β-glucuronidase and ASC did not fluctuate significantly. The data represent a baseline description of `health' for the expression and activity of these enzymes that can be used toward understanding the impact of environmental stressors on corals. Such knowledge can be applied to address causes of coral reef ecosystem decline and to monitor effectiveness of mitigation strategies. Achieving a better understanding of cause-and-effect relationships between putative stressors and biological responses in corals, and other marine invertebrates, can guide and evaluate mitigation and conservation approaches for marine ecosystem protection.

Characterization of the recalcitrant CYP1 phenotype found in Atlantic killifish (Fundulus heteroclitus) inhabiting a Superfund site on the Elizabeth River, VA

PubMed Central

Wills, Lauren P.; Matson, Cole W.; Landon, Chelsea D.; Di Giulio, Richard T.

2010-01-01

Fundulus heteroclitus (Atlantic killifish) found at the Atlantic Wood Industries Superfund site on the Elizabeth River (ER) in Portsmouth, VA (USA), have been shown to be resistant to the teratogenic effects of creosote-contaminated sediments found at this highly contaminated site. Many of the polycyclic aromatic hydrocarbons (PAHs) found at the ER are known to activate the aryl hydrocarbon receptor (AHR), and are thought to mediate their toxic effects through this pathway. Activation of the AHR results in the induction of several Phase I and II metabolic enzymes. It has been previously shown that the AHR of killifish from the ER are refractory to induction by AHR agonists. To more fully characterize this altered AHR response, we exposed embryos from the ER and from a reference site on King's Creek, VA (KC) to two PAHs, benzo[α]pyrene (BaP) and benzo[k]fluoranthene (BkF), and to the dioxin-like compound (DLC), 3,3′,4,4′,5-pentachlorobiphenyl (PCB126). We compared their developmental and molecular responses by screening the embryos for CYP1A enzyme activity, cardiac deformities, and mRNA expression of CYP1A, CYP1B1, CYP1C1, and AHR2. Basal gene expression of both CYP1A and CYP1B1 was 40% higher in the KC control embryos compared to those from the ER, while AHR2 and CYP1C1 were not significantly different between the populations. Exposure of KC embryos to BaP, BkF, and PCB126 induced CYP1A activity and cardiac deformities. In contrast, CYP1A activity was induced in ER embryos only in response to BkF exposure, although this induction in ER embryos was significantly lower than that observed in KC fish at comparable concentrations. ER embryos did not develop cardiac deformities in response to any of the chemicals tested. CYP1A, CYP1B1 and CYP1C1 mRNA were all significantly induced in the KC embryos after exposure to BaP, BkF and PCB126. Exposure to BaP and BkF in ER embryos resulted in a significant induction of CYP1A mRNA, albeit significantly lower than observed in KC fish. Interestingly, BaP exposure resulted in induction of CYP1B1 at comparable levels in embryos from both populations. CYP1s were not induced in ER embryos in response to PCB126, nor was CYP1C1 for any treatment examined. Additionally, AHR2 was not significantly induced for any of the treatment groups. This study further characterizes the AHR response in killifish, and provides greater insight into the adapted ER phenotype. The ER adaptation involves the suppression of normal AHR-inducible gene expression for all three CYP1 genes, and therefore is likely an alteration in AHR signaling or control. PMID:20471113

Blarina brevicauda as a biological monitor of polychlorinated biphenyls: Evaluation of hepatic cytochrome p450 induction

USGS Publications Warehouse

Russell, J.S.; Halbrook, R.S.; Woolf, A.; French, J.B.; Melancon, M.J.

2004-01-01

We assessed the value of short-tailed shrews (Blarina brevicauda) as a possible biomonitor for polychlorinated biphenyl pollution through measurement of the induction of hepatic cytochrome P450 and associated enzyme activities. First, we checked the inducibility of four monooxygenases (benzyloxyresorufin-O-dealkylase [BROD], ethoxyresorufin-O-dealkylase [EROD], methoxyresorufin-O-dealkylase [MROD], and pentoxyresorufin-O-dealkylase [PROD]) by measuring the activity of these enzymes in hepatic microsomes prepared from shrews injected with $-naphthoflavone ($NF) or phenobarbital (PB), typical inducers of cytochrome P4501A (CYP1A) and CYP2B enzyme families, respectively. Enzyme activity was induced in shrews that received $NF but not in shrews that received PB; PROD was not induced by either exposure. Later, shrews were exposed to a mixture of polychlorinated biphenyls (PCBs) (Aroclor 1242:1254, in 1:2 ratio) at 0.6, 9.6, and 150 ppm in food, for 31 d. Induction in these shrews was measured by specific enzyme activity (BROD, EROD, and MROD) in hepatic microsomes, by western blotting of solubilized microsomes against antibodies to CYP1A or CYP2B, and by duration of sodium pentobarbital-induced sleep. These three CYP enzymes were induced in shrews by PCBs at similar levels of exposure as in cotton rat (Sigmodon hispidus). Neither sleep time nor the amount of CYP2B family protein were affected by PCB exposure. Blarina brevicauda can be a useful biomonitor of PCBs that induce CYP1A, especially in habitats where they are the abundant small mammal.

Blarina brevicauda as a biological monitor of polychlorinated biphenyls: evaluation of hepatic cytochrome P450 induction.

PubMed

Russell, Julie S; Halbrook, Richard S; Woolf, Alan; French, John B; Melancon, Mark J

2004-08-01

We assessed the value of short-tailed shrews (Blarina brevicauda) as a possible biomonitor for polychlorinated biphenyl pollution through measurement of the induction of hepatic cytochrome P450 and associated enzyme activities. First, we checked the inducibility of four monooxygenases (benzyloxyresorufin-O-dealkylase [BROD], ethoxyresorufin-O-dealkylase [EROD], methoxyresorufin-O-dealkylase [MROD], and pentoxyresorufin-O-dealkylase [PROD]) by measuring the activity of these enzymes in hepatic microsomes prepared from shrews injected with beta-naphthoflavone (betaNF) or phenobarbital (PB), typical inducers of cytochrome P4501A (CYP1A) and CYP2B enzyme families, respectively. Enzyme activity was induced in shrews that received betaNF but not in shrews that received PB; PROD was not induced by either exposure. Later, shrews were exposed to a mixture of polychlorinated biphenyls (PCBs) (Aroclor 1242:1254, in 1:2 ratio) at 0.6, 9.6, and 150 ppm in food, for 31 d. Induction in these shrews was measured by specific enzyme activity (BROD, EROD, and MROD) in hepatic microsomes, by western blotting of solubilized microsomes against antibodies to CYP1A or CYP2B, and by duration of sodium pentobarbital-induced sleep. These three CYP enzymes were induced in shrews by PCBs at similar levels of exposure as in cotton rat (Sigmodon hispidus). Neither sleep time nor the amount of CYP2B family protein were affected by PCB exposure. Blarina brevicauda can be a useful biomonitor of PCBs that induce CYP1A, especially in habitats where they are the abundant small mammal.

No influence of the CYP2C19-selective inhibitor omeprazole on the pharmacokinetics of the dopamine receptor agonist rotigotine.

PubMed

Elshoff, Jan-Peer; Cawello, Willi; Andreas, Jens-Otto; Braun, Marina

2014-05-01

Rotigotine, a non-ergolinic dopamine receptor agonist administered transdermally via a patch, is metabolized by several cytochrome P-450 (CYP450) isoenzymes, including CYP2C19. This open-label, multiple-dose study evaluated the effect of omeprazole, a competitive inhibitor of CYP2C19, on the pharmacokinetics of rotigotine and its metabolites under steady-state conditions in healthy male subjects (of the extensive metabolizer phenotype, CYP2C19). Subjects received rotigotine 2 mg/24 hours on days 1-3, 4 mg/24 hours on days 4-12, and omeprazole 40 mg once daily on days 7-12 immediately after patch application. Blood and urine samples were collected on days 6 and 12 to evaluate rotigotine pharmacokinetic parameters alone and in the presence of omeprazole. Data from 37 subjects were available for pharmacokinetic analysis. Point estimates (90% confidence intervals, CI) for the ratios of AUC(0-24)SS and Cmax,SS of unconjugated rotigotine for the comparison rotigotine + omeprazole:rotigotine alone were close to 1 (0.9853 [0.9024, 1.0757] for AUC(0-24)SS and 1.0613 [0.9723, 1.1585] for Cmax,SS ) with 90% CIs within the acceptance range for bioequivalence (0.80, 1.25). Selective inhibition of CYP2C19 by omeprazole did not alter the steady-state pharmacokinetic profile of rotigotine or its metabolites. Thus, rotigotine dose adjustment is not required in patients receiving omeprazole, or other CYP2C19 inhibitors. © 2014, The American College of Clinical Pharmacology.

Clustering of ABCB1 and CYP2C19 Genetic Variants Predicts Risk of Major Bleeding and Thrombotic Events in Elderly Patients with Acute Coronary Syndrome Receiving Dual Antiplatelet Therapy with Aspirin and Clopidogrel.

PubMed

Galeazzi, Roberta; Olivieri, Fabiola; Spazzafumo, Liana; Rose, Giuseppina; Montesanto, Alberto; Giovagnetti, Simona; Cecchini, Sara; Malatesta, Gelsomina; Di Pillo, Raffaele; Antonicelli, Roberto

2018-06-23

The clinical efficacy of clopidogrel in secondary prevention of vascular events is hampered by marked inter-patient variability in drug response, which partially depends on genetic make-up. The aim of this pilot prospective study was to evaluate 12-month cardiovascular outcomes in elderly patients with acute coronary syndrome (ACS) receiving dual antiplatelet therapy (aspirin and clopidogrel) according to the clustering of CYP2C19 and ABCB1 genetic variants. Participants were 100 consecutive ACS patients who were genotyped for CYP2C19 (G681A and C-806T) and ABCB1 (C3435T) polymorphisms, which affect clopidogrel metabolism and bioavailability, using PCR-restriction fragment length polymorphism. They were then grouped as poor, extensive and ultra-rapid metabolisers based on the combination of CYP2C19 loss-of-function (CYP2C19*2) and gain-of-function (CYP2C19*17) alleles and ABCB1 alleles. The predictive value of each phenotype for acute vascular events was estimated based on 12-month cardiovascular outcomes. The poor metabolisers were at an increased risk of thrombotic events (OR 1.26; 95% CI 1.099-1.45; χ 2  = 5.676; p = 0.027), whereas the ultra-rapid metabolisers had a 1.31-fold increased risk of bleeding events compared with the poor and extensive metabolisers (OR 1.31; 95% CI 1.033-1.67; χ 2  = 5.676; p = 0.048). Logistic regression model, including age, sex, BMI and smoking habit, confirmed the differential risk of major events in low and ultra-rapid metabolisers. Our findings suggest that ACS patients classified as 'poor or ultra-rapid' metabolisers based on CYP2C19 and ABCB1 genotypes should receive alternative antiplatelet therapies to clopidogrel.

Effects of 2,4,6-trinitrotoluene (TNT) on phase I and phase II biotransformation enzymes in European eel Anguilla anguilla (Linnaeus, 1758).

PubMed

Della Torre, Camilla; Corsi, Ilaria; Arukwe, Augustine; Alcaro, Luigi; Amato, Ezio; Focardi, Silvano

2008-07-01

The aim of this study was to investigate effects of the explosive 2,4,6-trinitrotoluene (TNT) on liver drug metabolizing genes and enzymes in the European eel Anguilla anguilla as a model fish species. Eels were exposed in vivo for 6h and 24h to 0.5, 1 and 2.5mg/L nominal concentrations of TNT. Expression of CYP1A, glutathione-S-transferase (pi-class; GST) and uridine-diphosphate glucuronosyltransferase (1-family) (UDPGT) genes was investigated by RT-PCR, and 7-ethoxy- and 7-methoxyresorufin-O-dealkylases (EROD, MROD), NADPH cyt c reductase (NADPH red), UDPGT and GST enzyme activities were measured by biochemical assays. An in vitro study was also performed, measuring only EROD activity. TNT exposure produced no modulation of CYP1A transcript expression while a significant inhibition of EROD enzyme activity was observed and confirmed in vitro. UDPGT transcript increased dose-dependently only at 6h while the UDPGT activity tended to increase dose-dependently at 24h. GST gene expression increased after 24h and significant increases of GST activity were observed both at 6 and 24h only at the highest TNT concentration. An increase of NADPH red activity was observed at 24h. Our results seem to indicate an inhibitory effect of TNT on CYP1A-dependent catalytic activities and a possible involvement of phase II enzymes as well as NADPH red in TNT metabolism in eels.

Expression, function and regulation of mouse cytochrome P450 enzymes: comparison with human P450 enzymes.

PubMed

Hrycay, E G; Bandiera, S M

2009-12-01

The present review focuses on the expression, function and regulation of mouse cytochrome P450 (Cyp) enzymes. Information compiled for mouse Cyp enzymes is compared with data collected for human CYP enzymes. To date, approximately 40 pairs of orthologous mouse-human CYP genes have been identified that encode enzymes performing similar metabolic functions. Recent knowledge concerning the tissue expression of mouse Cyp enzymes from families 1 to 51 is summarized. The catalytic activities of microsomal, mitochondrial and recombinant mouse Cyp enzymes are discussed and their involvement in the metabolism of exogenous and endogenous compounds is highlighted. The role of nuclear receptors, such as the aryl hydrocarbon receptor, constitutive androstane receptor and pregnane X receptor, in regulating the expression of mouse Cyp enzymes is examined. Targeted disruption of selected Cyp genes has generated numerous Cyp null mouse lines used to decipher the role of Cyp enzymes in metabolic, toxicological and biological processes. In conclusion, the laboratory mouse is an indispensable model for exploring human CYP-mediated activities.

Prenatal administration of the cytochrome P4501A inducer, {Beta}-naphthoflavone (BNF), attenuates hyperoxic lung injury in newborn mice: Implications for bronchopulmonary dysplasia (BPD) in premature infants

DOE Office of Scientific and Technical Information (OSTI.GOV)

Couroucli, Xanthi I., E-mail: xanthic@bcm.edu; Liang Yanhong Wei; Jiang Weiwu

Supplemental oxygen contributes to the development of bronchopulmonary dysplasia (BPD) in premature infants. In this investigation, we tested the hypothesis that prenatal treatment of pregnant mice (C57BL/6J) with the cytochrome P450 (CYP)1A1 inducer, ss-napthoflavone (BNF), will lead to attenuation of lung injury in newborns (delivered from these dams) exposed to hyperoxia by mechanisms entailing transplacental induction of hepatic and pulmonary CYP1A enzymes. Pregnant mice were administered the vehicle corn oil (CO) or BNF (40 mg/kg), i.p., once daily for 3 days on gestational days (17-19), and newborns delivered from the mothers were either maintained in room air or exposed tomore » hyperoxia (> 95% O{sub 2}) for 1-5 days. After 3-5 days of hyperoxia, the lungs of CO-treated mice showed neutrophil infiltration, pulmonary edema, and perivascular inflammation. On the other hand, BNF-pretreated neonatal mice showed decreased susceptibility to hyperoxic lung injury. These mice displayed marked induction of ethoxyresorufin O-deethylase (EROD) (CYP1A1) and methoxyresorufin O-demethylase (MROD) (CYP1A2) activities, and levels of the corresponding apoproteins and mRNA levels until PND 3 in liver, while CYP1A1 expression alone was augmented in the lung. Prenatal BNF did not significantly alter gene expression of pulmonary NAD(P)H quinone reductase (NQO1). Hyperoxia for 24-72 h resulted in increased pulmonary levels of the F{sub 2}-isoprostane 8-iso-PGF{sub 2{alpha}}, whose levels were decreased in mice prenatally exposed to BNF. In conclusion, our results suggest that prenatal BNF protects newborns against hyperoxic lung injury, presumably by detoxification of lipid hydroperoxides by CYP1A enzymes, a phenomenon that has implications for prevention of BPD in infants. - Highlights: > Supplemental oxygen is routinely administered to premature infants. > Hyperoxia causes lung injury in experimental animals. > Prenatal treatment of mice with beta-naphthoflavone attenuates oxygen injury > Cytochrome P4501A enzymes play protective roles against lung injury« less

An ethinyl estradiol-levonorgestrel containing oral contraceptive does not alter cytochrome P4502C9 in vivo activity.

PubMed

Cherala, Ganesh; Pearson, Jacob; Maslen, Cheryl; Edelman, Alison

2014-03-01

Oral contraceptives have been in wide use for more than 50 years. Levonorgestrel, a commonly employed progestin component of combined oral contraceptives, was implicated in drug-drug interactions mediated via CYP2C9. Although in vitro studies refuted this interaction, there are no confirmatory in vivo studies. In the current study, we examined the phenotypic status of CYP2C9 using low-dose (125 mg) tolbutamide before and after oral contraceptive use in reproductive age women. Blood was collected 24 hours after the tolbutamide oral dose was administered, plasma was isolated, and tolbutamide concentration (C24) was measured using liquid chromatography-mass spectrometry. The natural logarithm of tolbutamide C24, a metric for CYP2C9 phenotype, was found to be equivalent (within 80%-125% equivalency boundaries) before and after oral contraceptive use. In conclusion, levonorgestrel-containing oral contraceptives, the most commonly used form of oral contraception, do not affect the status of the CYP2C9 enzyme. This suggests that it is safe to co-administer levonorgestrel-containing oral contraceptives and CYP2C9 substrates, which include a wide array of drugs.

An Ethinyl Estradiol-Levonorgestrel Containing Oral Contraceptive Does Not Alter Cytochrome P4502C9 In Vivo Activity

PubMed Central

Pearson, Jacob; Maslen, Cheryl; Edelman, Alison

2014-01-01

Oral contraceptives have been in wide use for more than 50 years. Levonorgestrel, a commonly employed progestin component of combined oral contraceptives, was implicated in drug–drug interactions mediated via CYP2C9. Although in vitro studies refuted this interaction, there are no confirmatory in vivo studies. In the current study, we examined the phenotypic status of CYP2C9 using low-dose (125 mg) tolbutamide before and after oral contraceptive use in reproductive age women. Blood was collected 24 hours after the tolbutamide oral dose was administered, plasma was isolated, and tolbutamide concentration (C24) was measured using liquid chromatography–mass spectrometry. The natural logarithm of tolbutamide C24, a metric for CYP2C9 phenotype, was found to be equivalent (within 80%–125% equivalency boundaries) before and after oral contraceptive use. In conclusion, levonorgestrel-containing oral contraceptives, the most commonly used form of oral contraception, do not affect the status of the CYP2C9 enzyme. This suggests that it is safe to coadminister levonorgestrel-containing oral contraceptives and CYP2C9 substrates, which include a wide array of drugs. PMID:24368832

Independent pseudogenization of CYP2J19 in penguins, owls and kiwis implicates gene in red carotenoid synthesis.

PubMed

Emerling, Christopher A

2018-01-01

Carotenoids have important roles in bird behavior, including pigmentation for sexual signaling and improving color vision via retinal oil droplets. Yellow carotenoids are diet-derived, but red carotenoids (ketocarotenoids) are typically synthesized from yellow precursors via a carotenoid ketolase. Recent research on passerines has provided evidence that a cytochrome p450 enzyme, CYP2J19, is responsible for this reaction, though it is unclear if this function is phylogenetically restricted. Here I provide evidence that CYP2J19 is the carotenoid ketolase common to Aves using the genomes of 65 birds and the retinal transcriptomes of 15 avian taxa. CYP2J19 is functionally intact and robustly transcribed in all taxa except for several species adapted to foraging in dim light conditions. Two penguins, an owl and a kiwi show evidence of genetic lesions and relaxed selection in their genomic copy of CYP2J19, and six owls show evidence of marked reduction in CYP2J19 retinal transcription compared to nine diurnal avian taxa. Furthermore, one of the owls appears to transcribe a CYP2J19 pseudogene. Notably, none of these taxa are known to use red carotenoids for sexual signaling and several species of owls and penguins represent the only birds known to completely lack red retinal oil droplets. The remaining avian taxa belong to groups known to possess red oil droplets, are known or expected to deposit red carotenoids in skin and/or plumage, and/or frequently forage in bright light. The loss and reduced expression of CYP2J19 is likely an adaptation to maximize retinal sensitivity, given that oil droplets reduce the amount of light available to the retina. Copyright © 2017 Elsevier Inc. All rights reserved.

In vitro effect of important herbal active constituents on human cytochrome P450 1A2 (CYP1A2) activity.

PubMed

Pan, Yan; Tiong, Kai Hung; Abd-Rashid, Badrul Amini; Ismail, Zakiah; Ismail, Rusli; Mak, Joon Wah; Ong, Chin Eng

2014-10-15

This study was designed to investigate eight herbal active constituents (andrographolide, asiaticoside, asiatic acid, madecassic acid, eupatorin, sinensetin, caffeic acid, and rosmarinic acid) on their potential inhibitory effects on human cytochrome P450 1A2 (CYP1A2) activity. A fluorescence-based enzyme assay was performed by co-incubating human cDNA-expressed CYP1A2 with its selective probe substrate, 3-cyano-7-ethoxycoumarin (CEC), in the absence or presence of various concentrations of herbal active constituents. The metabolite (cyano-hydroxycoumarin) formed was subsequently measured in order to obtain IC50 values. The results indicated that only eupatorin and sinensetin moderately inhibited CYP1A2 with IC50 values of 50.8 and 40.2 μM, while the other active compounds did not significantly affect CYP1A2 activity with IC50 values more than 100 μM. Ki values further determined for eupatorin and sinensetin were 46.4 and 35.2 μM, respectively. Our data indicated that most of the investigated herbal constituents have negligible CYP1A2 inhibitory effect. In vivo studies however may be warranted to ascertain the inhibitory effect of eupatorin and sinensetin on CYP1A2 activity in clinical situations. Copyright © 2014 Elsevier GmbH. All rights reserved.

Modulation of Xenobiotic Metabolizing Enzyme and Transporter Gene Expression in Primary Cultures of Human Hepatocytes by ToxCast Chemicals

EPA Science Inventory

ToxCast chemicals were assessed for induction or suppression of xenobiotic metabolizing enzyme and transporter gene expression using primary human hepatocytes. The mRNA levels of 14 target and 2 control genes were measured: ABCB1, ABCB11, ABCG2, SLCO1B1, CYP1A1, CYP1A2, CYP2B6, C...

Comparison of CYP2C9, CYP2C19, CYP2D6, ABCB1, and SLCO1B1 gene-polymorphism frequency in Russian and Nanai populations

PubMed Central

Sychev, Dmitrij Alekseevitch; Shuev, Grigorij Nikolaevich; Suleymanov, Salavat Shejhovich; Ryzhikova, Kristina Anatol’evna; Mirzaev, Karin Badavievich; Grishina, Elena Anatol’evna; Snalina, Natalia Evgenievna; Sozaeva, Zhannet Alimovna; Grabuzdov, Anton Mikhailovich; Matsneva, Irina Andreevna

2017-01-01

Background The efficiency and safety of drug therapy depends on the peculiarities of functioning of the P450 cytochrome group and transporting proteins. There are significant differences for single-nucleotide polymorphism (SNP) frequency. Materials and methods We studied the peculiarities of P450 cytochrome polymorphisms, SLCO1B1 transporting protein, and P-glycoprotein carriage in healthy volunteers in the Nanai ethnic group living in Russia, and compared them to the carriage of SNPs in the Russian population according to literature data. Results After performing the real-time polymerase chain reactions on the samples from 70 healthy volunteers from the Nanai group, for the CYP2C9*2C430T polymorphism we determined 70 CC-genotype carriers. As for the CYP2C9*3A1075C polymorphism, we found 62 AA-genotype carriers and eight AC-genotype carriers. For the CYP2C19*2G681A polymorphism, we determined 39 GG-genotype carriers and 28 GA-genotype carriers, for the CYP2C19*3G636A polymorphism 58 GG-genotype carriers and 12 GA-genotype carriers, and for the CYP2C19*17C806T polymorphism 67 CC-genotype carriers and three CT-genotype carriers. For the CYP2D6*4G1846A polymorphism, the GG genotype had 68 carriers, and the GA genotype two carriers. For the ABCB1*6C3435T polymorphism, there were 19 CC-genotype carriers and 39 CT-genotype carriers. For the SLCO1B1*5T521C polymorphism, the TT genotype had 41 carriers and the CT genotype 25 carriers. The distribution of genotypes fitted the Hardy–Weinberg equilibrium for all the polymorphisms, except those of CYP2C9*2. There were also significant differences in allele frequencies for some polymorphisms between the Nanais and the Russians. Conclusion In the Nanai population, there are polymorphisms connected with the decrease in safety and efficiency of drug therapy. Studying the ethnic differences might influence the determination of priority in the introduction of pharmacogenetic tests in clinical practice in different regions of Russia. PMID:28435307

The effect of the cytochrome P450 CYP2C8 polymorphism on the disposition of (R)-ibuprofen enantiomer in healthy subjects

PubMed Central

Martínez, Carmen; García-Martín, Elena; Blanco, Gerardo; Gamito, Francisco J G; Ladero, José M; Agúndez, José A G

2005-01-01

Aims To study the effect of CYP2C8*3, the most common CYP2C8 variant allele on the dis-position of (R)-ibuprofen and the association of CYP2C8*3 with variant CYP2C9 alleles. Methods Three hundred and fifty-five randomly selected Spanish Caucasians were screened for the common CYP2C8 and CYP2C9 mutations. The pharmacokinetics of (R)-ibuprofen were studied in 25 individuals grouped into different CYP2C8 genotypes. Results The allele frequency of CYP2C8*3 (0.17) was found to be higher than that reported for other Caucasian populations (P = 0.0001). The frequencies of CYP2C9*2 and CYP2C9*3 were 0.19 (0.16–0.21) and 0.10 (0.08–0.12), respectively. An association between CYP2C8*3 and CYP2C9*2 alleles was observed, occurring together at a frequency 2.4-fold higher than expected for a random association of alleles (P = 0.0001). The presence of the CYP2C8*3 allele was found to influence the pharmacokinetics of (R)-ibuprofen in a gene–dose effect manner. Thus, after administration of 400 mg ibuprofen, the plasma half-life (95% confidence intervals) for individuals with genotypes CYP2C8*1/*1, CYP2C8*1/*3 and CYP2C8*3/*3, was 2.0 h (1.8–2.2), 4.2 h (1.9–6.5; P < 0.05) and 9.0 h (7.8–10.2; P < 0.002), respectively. A statistically significant trend with respect to the number of variant CYP2C8*3 alleles was also observed for the area under the concentration-time curve (P < 0.025), and drug clearance (P < 0.03). Conclusion Polymorphism of the CYP2C8 gene was found to be common, with nearly 30% of the population studied carrying the variant CYP2C8*3 allele. The presence of the latter caused a significant effect on the disposition of (R)-ibuprofen. This suggests that a substantial proportion of Caucasian subjects may show alterations in the disposition of drugs that are CYP2C8 substrates. PMID:15606441

Cytochrome P450 2D6 variants in a Caucasian population: Allele frequencies and phenotypic consequences

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sachse, C.; Brockmoeller, J.; Bauer, S.

Cytochrome P450 2D6 (CYP2D6) metabolizes many important drugs. CYP2D6 activity ranges from complete deficiency to ultrafast metabolism, depending on at least 16 different known alleles. Their frequencies were determined in 589 unrelated German volunteers and correlated with enzyme activity measured by phenotyping with dextromethorphan or debrisoquine. For genotyping, nested PCR-RFLP tests from a PCR amplificate of the entire CYP2D6 gene were developed. The frequency of the CYP2D6*1 allele coding for extensive metabolizer (EM) phenotype was .364. The alleles coding for slightly (CYP2D6*2) or moderately (*9 and *10) reduced activity (intermediate metabolizer phenotype [IM]) showed frequencies of .324, .018, and .015,more » respectively. By use of novel PCR tests for discrimination, CYP2D6 gene duplication alleles were found with frequencies of.005 (*1 x 2), .013 (* 2 x 2), and .001 (*4 x 2). Frequencies of alleles with complete deficiency (poor metabolizer phenotype [PM]) were .207 (*4), .020 (*3 and *5), .009 (*6), and .001 (*7, *15, and *16). The defective CYP2D6 alleles *8, *11, *12, *13, and *14 were not found. All 41 PMs (7.0%) in this sample were explained by five mutations detected by four PCR-RFLP tests, which may suffice, together with the gene duplication test, for clinical prediction of CYP2D6 capacity. Three novel variants of known CYP2D6 alleles were discovered: *1C (T{sub 1957}C), *2B (additional C{sub 2558}T), and *4E (additional C{sub 2938}T). Analysis of variance showed significant differences in enzymatic activity measured by the dextromethorphan metabolic ratio (MR) between carriers of EN/PM (mean MR = .006) and IM/PM (mean MR = .014) alleles and between carriers of one (mean MR = .009) and two (mean MR = .003) functional alleles. The results of this study provide a solid basis for prediction of CYP2D6 capacity, as required in drug research and routine drug treatment. 35 refs., 4 figs., 5 tabs.« less

Functional expression of a putative geraniol 8-hydroxylase by reconstitution of bacterially expressed plant CYP76F45 and NADPH-cytochrome P450 reductase CPR I from Croton stellatopilosus Ohba.

PubMed

Sintupachee, Siriluk; Promden, Worrawat; Ngamrojanavanich, Nattaya; Sitthithaworn, Worapan; De-Eknamkul, Wanchai

2015-10-01

While attempting to isolate the enzyme geranylgeraniol 18-hydroxylase, which is involved in plaunotol biosynthesis in Croton stellatopilosus (Cs), the cDNAs for a cytochrome P450 monooxygenase(designated as CYP76F45) and an NADPH-cytochrome P450 reductase (designated as CPR I based on its classification) were isolated from the leaf. The CYP76F45 and CsCPR I genes have open reading frames (ORFs) encoding 507- and 711-amino acid proteins with predicted relative molecular weights of 56.7 and 79.0 kDa,respectively. Amino acid sequence comparison showed that both CYP76F45 (63–73%) and CsCPR I (79–83%) share relatively high sequence identities with homologous proteins in other plant species.Phylogenetic tree analysis confirmed that CYP76F45 belongs to the CYP76 family and that CsCPR I belongs to Class I of dicotyledonous CPRs, with both being closely related to Ricinus communis genes. Functional characterization of both enzymes, each expressed separately in Escherichia coli as recombinant proteins,showed that only simultaneous incubation of the membrane bound proteins with the substrate geraniol (GOH) and the coenzyme NADPH could form 8-hydroxygeraniol. The enzyme mixture could also utilize acyclic sesquiterpene farnesol (FOH) with a comparable substrate preference ratio (GOH:FOH) of 54:46. The levelsof the CYP76F45 and CsCPR I transcripts in the shoots, leaves and twigs of C. stellatopilosus were correlated with the levels of a major monoterpenoid indole alkaloid, identified tentatively as 19-Evallesamine,that accumulated in these plant parts. These results suggested that CYP76F45 and CPR I function as the enzyme geraniol-8-hydroxylase (G8H), which is likely to be involved in the biosynthesis of the indole alkaloid in C. stellatopilosus [corrected]. Copyright © 2015 Elsevier Ltd. All rights reserved.

Inhibition of human cytochromes P450 2A6 and 2A13 by flavonoids, acetylenic thiophenes and sesquiterpene lactones from Pluchea indica and Vernonia cinerea.

PubMed

Boonruang, Supattra; Prakobsri, Khanistha; Pouyfung, Phisit; Srisook, Ekaruth; Prasopthum, Aruna; Rongnoparut, Pornpimol; Sarapusit, Songklod

2017-12-01

The human liver cytochrome P450 (CYP) 2A6 and the respiratory CYP2A13 enzymes play role in nicotine metabolism and activation of tobacco-specific nitrosamine carcinogens. Inhibition of both enzymes could offer a strategy for smoking abstinence and decreased risks of respiratory diseases and lung cancer. In this study, activity-guided isolation identified four flavonoids 1-4 (apigenin, luteolin, chrysoeriol, quercetin) from Vernonia cinerea and Pluchea indica, four hirsutinolide-type sesquiterpene lactones 5-8 from V. cinerea, and acetylenic thiophenes 9-11 from P. indica that inhibited CYP2A6- and CYP2A13-mediated coumarin 7-hydroxylation. Flavonoids were most effective in inhibition against CYP2A6 and CYP2A13, followed by thiophenes, and hirsutinolides. Hirsutinolides and thiophenes exhibited mechanism-based inhibition and in irreversible mode against both enzymes. The inactivation kinetic K I values of hirsutinolides against CYP2A6 and CYP2A13 were 5.32-15.4 and 0.92-8.67 µM, respectively, while those of thiophenes were 0.11-1.01 and 0.67-0.97 µM, respectively.

Exploring venlafaxine pharmacokinetic variability with a phenotyping approach, a multicentric french-swiss study (MARVEL study).

PubMed

Lloret-Linares, Célia; Daali, Youssef; Chevret, Sylvie; Nieto, Isabelle; Molière, Fanny; Courtet, Philippe; Galtier, Florence; Richieri, Raphaëlle-Marie; Morange, Sophie; Llorca, Pierre-Michel; El-Hage, Wissam; Desmidt, Thomas; Haesebaert, Frédéric; Vignaud, Philippe; Holtzmann, Jerôme; Cracowski, Jean-Luc; Leboyer, Marion; Yrondi, Antoine; Calvas, Fabienne; Yon, Liova; Le Corvoisier, Philippe; Doumy, Olivier; Heron, Kyle; Montange, Damien; Davani, Siamak; Déglon, Julien; Besson, Marie; Desmeules, Jules; Haffen, Emmanuel; Bellivier, Frank

2017-11-07

It is well known that the standard doses of a given drug may not have equivalent effects in all patients. To date, the management of depression remains mainly empirical and often poorly evaluated. The development of a personalized medicine in psychiatry may reduce treatment failure, intolerance or resistance, and hence the burden and costs of mood depressive disorders. The Geneva Cocktail Phenotypic approach presents several advantages including the "in vivo" measure of different cytochromes and transporter P-gp activities, their simultaneous determination in a single test, avoiding the influence of variability over time on phenotyping results, the administration of low dose substrates, a limited sampling strategy with an analytical method developed on DBS analysis. The goal of this project is to explore the relationship between the activity of drug-metabolizing enzymes (DME), assessed by a phenotypic approach, and the concentrations of Venlafaxine (VLX) + O-demethyl-venlafaxine (ODV), the efficacy and tolerance of VLX. This study is a multicentre prospective non-randomized open trial. Eligible patients present a major depressive episode, MADRS over or equal to 20, treatment with VLX regardless of the dose during at least 4 weeks. The Phenotype Visit includes VLX and ODV concentration measurement. Following the oral absorption of low doses of omeprazole, midazolam, dextromethorphan, and fexofenadine, drug metabolizing enzymes activity is assessed by specific metabolite/probe concentration ratios from a sample taken 2 h after cocktail administration for CYP2C19, CYP3A4, CYP2D6; and by the determination of the limited area under the curve from the capillary blood samples taken 2-3 and 6 h after cocktail administration for CYP2C19 and P-gp. Two follow-up visits will take place between 25 and 40 days and 50-70 days after inclusion. They include assessment of efficacy, tolerance and observance. Eleven french centres are involved in recruitment, expected to be completed within approximately 2 years with 205 patients. Metabolic ratios are determined in Geneva, Switzerland. By showing an association between drug metabolism and VLX concentrations, efficacy and tolerance, there is a hope that testing drug metabolism pathways with a phenotypical approach would help physicians in selecting and dosing antidepressants. The MARVEL study will provide an important contribution to increasing the knowledge of VLX variability and in optimizing the use of methods of personalized therapy in psychiatric settings. ClinicalTrials.gov NCT02590185 (10/27/2015). This study is currently recruiting participants.

Increased activity of CYP3A enzyme in primary cultures of rat hepatocytes treated with docetaxel: comparative evaluation with paclitaxel.

PubMed

Nallani, S C; Genter, M B; Desai, P B

2001-08-01

Docetaxel, a potent antimicrotubule agent widely used in the treatment of ovarian, breast and lung cancer, is extensively metabolized in various animal species, including humans. The metabolism of docetaxel to its primary metabolite, hydroxydocetaxel, is mediated by cytochrome P450 isozymes CYP3A2 and CYP3A4 in rats and humans, respectively. Several substrates of enzymes belonging to the CYP3A subfamily are known to induce different CYP isozymes, including CYP3A enzymes. Recently, paclitaxel, a compound structurally related to docetaxel, has been shown to significantly elevate the expression of CYP3A in rat and human hepatocytes. In this study we investigated the influence of docetaxel, employed at clinically relevant concentrations, on the level and the activity of cytochrome P450 3A in primary cultures of rat hepatocytes. Rat hepatocytes were treated with different concentrations of docetaxel, paclitaxel and other CYP3A inducers. Testosterone 6beta-hydroxylase activity of intact hepatocytes was used as a marker for CYP3A. The immunoreactive CYP3A levels in the S-9 fractions were determined by Western blot analysis. We observed that by day 3 of drug treatment, docetaxel at concentration in the range of 2.5-10 microM increased the CYP3A enzymatic activity and the immunoreactive CYP3A levels in a concentration-dependent manner. At the 10 microM level, docetaxel caused a twofold increase in the CYP3A activity and a threefold increase in the immunoreactive CYP3A levels. However, the docetaxel-mediated CYP3A activity and enzyme level increase were significantly lower than those mediated by paclitaxel and dexamethasone. A comparison of the testosterone 6beta-hydroxylation activity in hepatocytes treated with these agents at a concentration of 5 microM each yielded the following rank order of induction capacity: dexamethasone > paclitaxel > docetaxel (15-fold, 5-fold, 2.2-fold, respectively). Taken together, our findings raise the possibility that docetaxel at clinically relevant concentrations increases CYP3A activity. The potential for docetaxel-mediated changes in the metabolism of other coadministered drugs and its own metabolism, in relation to that due to paclitaxel, are discussed.

Gastroprotective Efficacy and Safety Evaluation of Scoparone Derivatives on Experimentally Induced Gastric Lesions in Rodents

PubMed Central

Son, Dong Ju; Lee, Gyung Rak; Oh, Sungil; Lee, Sung Eun; Choi, Won Sik

2015-01-01

This study investigated the gastroprotective efficacy of synthesized scoparone derivatives on experimentally induced gastritis and their toxicological safety. Six scoparone derivatives were synthesized and screened for gastroprotective activities against HCl/ethanol- and indomethacin-induced gastric ulcers in rats. Among these compounds, 5,6,7-trimethoxycoumarin and 6,7,8-trimethoxycoumarin were found to have gastroprotective activity greater than the standard drug rebamipide; 6-methoxy-7,8-methylenedioxycoumarin, 6-methoxy-7,8-(1-methoxy)-methylenedioxycoumarin, 6,7-methylenedioxycoumarin, and 6,7-(1-methoxy)-methylenedioxycoumarin were found to be equipotent or less potent that of rebamipide. Pharmacological studies suggest that the presence of a methoxy group at position C-5 or C-8 of the scoparone’s phenyl ring significantly improves gastroprotective activity, whereas the presence of a dioxolane ring at C-6, C-7, or C-8 was found to have decreased activity. In order to assess toxicological safety, two of the potent gastroprotective scoparone derivatives—5,6,7-trimethoxycoumarin and 6,7,8-trimethoxycoumarin—were examined for their acute toxicity in mice as well as their effect on cytochrome P450 (CYP) enzyme activity. These two compounds showed low acute oral toxicity in adult male and female mice, and caused minimal changes to CYP3A4 and CYP2C9 enzyme activity. These results indicate that compared to other scoparone derivatives, 5,6,7-trimethoxycoumarin and 6,7,8-trimethoxycoumarin can improve gastroprotective effects, and they have low toxicity and minimal effects on drug-metabolizing enzymes. PMID:25781220

Serum-free culture of primary human hepatocytes in a miniaturized hollow-fibre membrane bioreactor for pharmacological in vitro studies.

PubMed

Lübberstedt, Marc; Müller-Vieira, Ursula; Biemel, Klaus M; Darnell, Malin; Hoffmann, Stefan A; Knöspel, Fanny; Wönne, Eva C; Knobeloch, Daniel; Nüssler, Andreas K; Gerlach, Jörg C; Andersson, Tommy B; Zeilinger, Katrin

2015-09-01

Primary human hepatocytes represent an important cell source for in vitro investigation of hepatic drug metabolism and disposition. In this study, a multi-compartment capillary membrane-based bioreactor technology for three-dimensional (3D) perfusion culture was further developed and miniaturized to a volume of less than 0.5 ml to reduce demand for cells. The miniaturized bioreactor was composed of two capillary layers, each made of alternately arranged oxygen and medium capillaries serving as a 3D culture for the cells. Metabolic activity and stability of primary human hepatocytes was studied in this bioreactor in the presence of 2.5% fetal calf serum (FCS) under serum-free conditions over a culture period of 10 days. The miniaturized bioreactor showed functions comparable to previously reported data for larger variants. Glucose and lactate metabolism, urea production, albumin synthesis and release of intracellular enzymes (AST, ALT, GLDH) showed no significant differences between serum-free and serum-supplemented bioreactors. Activities of human-relevant cytochrome P450 (CYP) isoenzymes (CYP1A2, CYP3A4/5, CYP2C9, CYP2D6, CYP2B6) analyzed by determination of product formation rates from selective probe substrates were also comparable in both groups. Gene expression analysis showed moderately higher expression in the majority of CYP enzymes, transport proteins and enzymes of Phase II metabolism in the serum-free bioreactors compared to those maintained with FCS. In conclusion, the miniaturized bioreactor maintained stable function over the investigated period and thus provides a suitable system for pharmacological studies on primary human hepatocytes under defined serum-free conditions. Copyright © 2012 John Wiley & Sons, Ltd.

Developmental programming: prenatal steroid excess disrupts key members of intraovarian steroidogenic pathway in sheep.

PubMed

Padmanabhan, Vasantha; Salvetti, Natalia R; Matiller, Valentina; Ortega, Hugo H

2014-09-01

Prenatal testosterone (T) excess disrupts ovarian cyclicity and increases circulating estradiol levels as well as follicular recruitment and persistence culminating in multifollicular ovary similar to women with polycystic ovary syndrome. We tested whether prenatal T excess, by androgenic or estrogenic action, disrupts the steroid biosynthetic machinery in sheep in a cell-, follicle stage-, age-, and treatment-specific manner consistent with the ovarian disruptions and increased estradiol release. Impact of T/dihydrotestosterone (DHT) treatments from days 30-90 of gestation on steroidogenic acute regulatory protein, 3β-hydroxysteroid dehydrogenase, cytochrome P-450 17α-hydroxylase/C17, 20-lyase (CYP17A1), and cytochrome P-450 aromatase (CYP19A1) were examined on fetal day 90, 140 and 10 months (postpubertal), and 21 months (adult, no DHT group) of age by immunohistochemistry. All 4 markers changed in a cell-, follicle stage-, and age-specific manner. Both treatments increased steroidogenic acute regulatory protein expression in preantral follicles of postpubertal and adult females. Effects of prenatal T and DHT on 3β-hydroxysteroid dehydrogenase differed in a follicle- and age-specific manner. CYP17A1 was reduced in the theca interna of antral follicles by T, but not DHT, in 10- and 21-month-old females. CYP19A1 was reduced by both T and DHT at all ages barring an increase on fetal day 140. Reduced granulosa CYP19A1 and thecal CYP17A1 in adults likely disrupt the intrafollicular androgen/estrogen balance contributing to follicular persistence. The reduced thecal CYP17A1 expression suggests that the hyperandrogenic ovarian phenotype may originate from increased enzyme activity or alternatively via a different isoform of CYP17. The reduced CYP19A1 in antral follicles of adults indicates that the increased circulating estradiol release likely arises from the increased number of persisting follicles.

Effects of octylphenol on the expression of StAR, CYP17 and CYP19 in testis of Rana chensinensis.

PubMed

Bai, Yao; Li, Xin-Yi; Liu, Zhi-Jun; Zhang, Yu-Hui

2017-04-01

It has been proposed that a decline in sperm quality is associated with exposure to environmental chemicals with estrogenic activity. Seeking possible explanations for this effect, this study investigated the effects of octylphenol (OP) on the synthesis of steroid hormones in amphibian. Rana chensinensis were exposed to 10 -8 , 10 -7 and 10 -6 mol/L OP after 10, 20, 30 and 40 days. The cDNA fragments of StAR (274bp), CYP17 (303bp) and CYP19 (322bp) were cloned. In situ hybridization and immunohistochemistry revealed that positive signals of StAR, CYP17, CYP19 mRNA and proteins mainly in the Leydig cells of testes. Real-time PCR showed that up-regulation of StAR and CYP19, and down-regulation of CYP17 after exposure to 10 -8 , 10 -7 and 10 -6 mol/L OP. The results suggest that OP can alter transcriptions of StAR, CYP17 and CYP19, thus disturb the expressions of StAR, P450c17 and P450arom, thereby adversely affect steroid synthesis. Copyright © 2017 Elsevier B.V. All rights reserved.

Pharmacogenetic approach to losartan in Marfan patients: a starting point to improve dosing regimen?

PubMed

Falvella, Felicia Stefania; Marelli, Susan; Cheli, Stefania; Montanelli, Stefano; Viecca, Federico; Salvi, Lucia; Ferrara, Alfio; Clementi, Emilio; Trifirò, Giuliana; Pini, Alessandro

2016-09-01

Losartan is under evaluation for managing Marfan patients with aortic root dilatation. Cytochrome P450 (CYP) enzymes convert losartan to E3174 active metabolite. The aim of this study is to describe the distribution of CYP2C9*2, CYP2C9*3, CYP3A4*22 and CYP3A5*3 defective alleles, according to losartan tolerance in paediatric Marfan patients. We genotyped 53 paediatric Marfan patients treated with losartan. The rate of aortic root dilatation was evaluated using the delta z-score variation. Differences in tolerated losartan daily doses with respect to CYP metabolic classes were assessed through the Kruskal-Wallis test. The losartan daily dose spans from 0.16 to 2.50 mg/kg (median 1.10 mg/kg). As we expect from the pharmacokinetics pathway, we observe highest tolerated dose in CYP2C9 poor metabolisers (median 1.50 mg/kg, interquartile range 1.08-1.67 mg/kg); however, this difference is not statistically significant. The optimal dose of angiotensin receptor blocker is not known, and no data are available about losartan pharmacogenetic profile in Marfan syndrome; we have proposed a strategy to tackle this issue based on evaluating the major genetic polymorphisms involved in the losartan conversion into active carboxylic acid metabolite. Further studies are needed to support the use of genetic polymorphisms as predictors of the right dose of losartan.

Rapid screening of commercially available herbal products for the inhibition of major human hepatic cytochrome P450 enzymes using the N-in-one cocktail.

PubMed

Sevior, D K; Hokkanen, J; Tolonen, A; Abass, K; Tursas, L; Pelkonen, O; Ahokas, J T

2010-04-01

Self-administration of complementary products concurrently with conventional medication is increasingly common. The potential for cytochrome P450 (CYP) inhibition requires investigation. The N-in-one assay with ten probe substrates for nine CYPs was used with human liver microsomes to investigate ten products. CYP inhibition was measured in a single liquid chromatography-tandem mass spectrometry (LC/MS-MS) analysis. Estimated IC(50)-values were determined for the extracts that produced significant inhibition (less than 100 microg ml(-1)). Inhibition of CYP2C19 by dong quai (IC(50) = 13.7-14.3 microg ml(-1) for the methanolic extract) and CYP2D6 by goldenseal (IC(50) = 6.7 and 6.3 microg ml(-1) for the aqueous and methanolic extracts, respectively), are of particular concern as the potential for adverse interactions is high. The inhibition of CYP2C8 by horsetail (IC(50) = 93 microg ml(-1) for the aqueous extract) requires further investigation, as the potential for concurrent use with products that require CYP2C8 for metabolism is significant. CYP3A4 inhibition varied depending on the probe reaction being monitored. The earlier reported findings of inhibition by black cohosh, goldenseal and gotu kola were confirmed. The present work has shown that the N-in-one cocktail is a rapid and reliable method that can be used as an initial screen to help prioritize products that require more detailed investigations and it can also be applied to monitor product variability.

Common CYP2D6 polymorphisms affecting alternative splicing and transcription: long-range haplotypes with two regulatory variants modulate CYP2D6 activity

PubMed Central

Wang, Danxin; Poi, Ming J.; Sun, Xiaochun; Gaedigk, Andrea; Leeder, J. Steven; Sadee, Wolfgang

2014-01-01

Cytochrome P450 2D6 (CYP2D6) is involved in the metabolism of 25% of clinically used drugs. Genetic polymorphisms cause substantial variation in CYP2D6 activity and serve as biomarkers guiding drug therapy. However, genotype–phenotype relationships remain ambiguous except for poor metabolizers carrying null alleles, suggesting the presence of yet unknown genetic variants. Searching for regulatory CYP2D6 polymorphisms, we find that a SNP defining the CYP2D6*2 allele, rs16947 [R296C, 17–60% minor allele frequency (MAF)], previously thought to convey normal activity, alters exon 6 splicing, thereby reducing CYP2D6 expression at least 2-fold. In addition, two completely linked SNPs (rs5758550/rs133333, MAF 13–42%) increase CYP2D6 transcription more than 2-fold, located in a distant downstream enhancer region (>100 kb) that interacts with the CYP2D6 promoter. In high linkage disequilibrium (LD) with each other, rs16947 and the enhancer SNPs form haplotypes that affect CYP2D6 enzyme activity in vivo. In a pediatric cohort of 164 individuals, rs16947 alone (minor haplotype frequency 28%) was associated with reduced CYP2D6 metabolic activity (measured as dextromethorphan/metabolite ratios), whereas rs5758550/rs133333 alone (frequency 3%) resulted in increased CYP2D6 activity, while haplotypes containing both rs16947 and rs5758550/rs133333 were similar to the wild-type. Other alleles used in biomarker panels carrying these variants such as CYP2D6*41 require re-evaluation of independent effects on CYP2D6 activity. The occurrence of two regulatory variants of high frequency and in high LD, residing on a long haplotype, highlights the importance of gene architecture, likely shaped by evolutionary selection pressures, in determining activity of encoded proteins. PMID:23985325

Identification of the time-point which gives a plasma rabeprazole concentration that adequately reflects the area under the concentration-time curve.

PubMed

Niioka, Takenori; Uno, Tsukasa; Yasui-Furukori, Norio; Shimizu, Mikiko; Sugawara, Kazunobu; Tateishi, Tomonori

2006-10-01

The purpose of this study is to evaluate whether a simple formula using limited blood samples can predict the area under the plasma rabeprazole concentration-time curve (AUC) in co-administration with CYP inhibitors. A randomized double-blind placebo-controlled crossover study design in three phases was conducted at intervals of 2 weeks. Twenty-one healthy Japanese volunteers, including three CYP2C19 genotype groups, took a single oral 20-mg dose of rabeprazole after three 6-day pretreatments, i.e., clarithromycin 800 mg/day, fluvoxamine 50 mg/day, and placebo. Prediction formulas of the AUC were derived from pharmacokinetics data of 21 subjects in three phases using multiple linear regression analysis. Ten blood samples were collected over 24 h to calculate AUC. Plasma concentrations of rabeprazole was measured by an HPLC-assay (l.l.q.=1 ng/ml). The AUC was based on all the data sets (n=63). The linear regression using two points (C3 and C6) could predict AUC(0-infinity) precisely, irrespective of CYP2C19 genotypes and CYP inhibitors (AUC(0-infinity)=1.39xC3+7.17xC6+344.14, r (2)=0.825, p<0.001). The present study demonstrated that the AUC of rabeprazole can be estimated by the simple formula using two-point concentrations. This formula can be more accurate for the prediction of AUC estimation than that reflected by CYP2C19 genotypes without any determination, even if there are significant differences for the CYP2C19 genotypes. Therefore, this prediction formula might be useful to evaluate whether CYP2C19 genotypes really reflects the curative effect of rabeprazole.

Clinical significance of CYP2C19 polymorphisms on the metabolism and pharmacokinetics of 11β-hydroxysteroid dehydrogenase type-1 inhibitor BMS-823778.

PubMed

Cheng, Yaofeng; Wang, Lifei; Iacono, Lisa; Zhang, Donglu; Chen, Weiqi; Gong, Jiachang; Humphreys, William Griffith; Gan, Jinping

2018-01-01

BMS-823778 is an inhibitor of 11β-hydroxysteroid dehydrogenase type-1, and thus a potential candidate for Type 2 diabetes treatment. Here, we investigated the metabolism and pharmacokinetics of BMS-823778 to understand its pharmacokinetic variations in early clinical trials. The metabolism of BMS-823778 was characterized in multiple in vitro assays. Pharmacokinetics were evaluated in healthy volunteers, prescreened as CYP2C19 extensive metabolizers (EM) or poor metabolizers (PM), with a single oral dose of [ 14 C]BMS-823778 (10 mg, 80 μCi). Three metabolites (<5%) were identified in human hepatocytes and liver microsomes (HLM) incubations, including two hydroxylated metabolites (M1 and M2) and one glucuronide conjugate (M3). As the most abundant metabolite, M1 was formed mainly through CYP2C19. M1 formation was also correlated with CYP2C19 activities in genotyped HLM. In humans, urinary excretion of dosed radioactivity was significantly higher in EM (68.8%; 95% confidence interval 61.3%, 76.3%) than in PM (47.0%; 43.5%, 50.6%); only small portions (<2%) were present in faeces or bile from both genotypes. In plasma, BMS-823778 exposure in PM was significantly (5.3-fold, P = 0.0097) higher than in EM. Furthermore, total radioactivity exposure was significantly higher (P < 0.01) than BMS-823778 exposure in all groups, indicating the presence of metabolites. M1 was the only metabolite observed in plasma, and much lower in PM. In urine, the amount of M1 and its oxidative metabolite in EM was 7-fold of that in PM, while more glucuronide conjugates of BMS-823778 and M1 were excreted in PM. CYP2C19 polymorphisms significantly impacted systemic exposure and metabolism pathways of BMS-823778 in humans. © 2017 The British Pharmacological Society.

EFFECT OF CYP2C19 GENETIC POLYMORPHISMS ON THE EFFICACY OF PROTON PUMP INHIBITOR-BASED TRIPLE ERADICATION THERAPY IN SLAVIC PATIENTS WITH PEPTIC ULCERS: A META-ANALYSIS.

PubMed

Denisenko, N P; Sychev, D A; Sizova, Zh M; Rozhkov, A V; Kondrashov, A V

Several meta-analyzes reported the effect of CYP2C19 genetic polymorphisms on the efficacy of proton pump inhibitor-based triple therapy for Helicobacter pylori eradication. Most of the studies which were included in these meta-analyzes were held on Asian population. Thus, there is lack of information about the effect of CYP2C19 genetic polymorphisms on the efficacy of proton pump inhibitor-based triple eradication therapy in Slavic patients with peptic ulcers. The aim of the study - to determine whether CYP2C19 affect the efficacy of proton pump inhibitor-based triple eradica- tion therapy in Slavic patients with peptic ulcers. Data search was performed using Russian index of scientific citation database, Google Scholar and MEDLINE PubMed. Statistics was held in Review Manager v 5.3. The odds ratio (OR) and 95% confidence interval (95% Cl) for eradication of H.pylori was estimated in a fixed-effect model when no heterogeneity across the studies was indicated. Four articles published between 2008 and 2015 were included in meta-analysis (three Russian studies, one Polish study). Eradication rates were significantly lower in CYP2C19 extensive metabolizers of proton pump inhibitors than in a combined group of intermediate and poor metabolizers (OR = 1,90, CI-95% 1,08-3,34, p = 0,03; heterogeneity: 12= 0%, p = 0,74). We also found that proton pump inhibitor-based triple eradication therapy achieved higher rates in poor metabolizers than in a combined group of intermediate and extensive metabolizers of CYP2C19 (OR= 5,48 CI-95% 1,51-19,93, p = 0,01; heterogeneity: F= 0%, p = 0,66). The impact of CYP2C19 genetic polymorphisms on the efficacy of proton pump inhibitor-based triple eradication therapy in Slavic patients appears significant.

The effect of cytochrome P2C19 and interleukin-1 polymorphisms on H. pylori eradication rate of 1-week triple therapy with omeprazole or rabeprazole, amoxycillin and clarithromycin in Chinese people.

PubMed

Zhang, L; Mei, Q; Li, Q S; Hu, Y M; Xu, J M

2010-12-01

Genetic polymorphism of interleukin (IL)-1β and IL-1 receptor antagonist (IL-1rα) are associated with efficacy of acid suppression, whereas cytochrome P (CYP) 2C19 polymorphism influences the metabolism of proton pump inhibitor family. Thus, CYP2C19 and IL-1 polymorphisms may affect the efficacy of H. pylori eradication therapy. We compared the efficacies of omeprazole and rabeprazole on eradication of H. pylori in relation to CYP2C19, IL-1B and IL-1RN genotypes in Chinese people. Two hundred and forty Chinese with peptic ulcer disease were randomly assigned to the following regimens: amoxicillin and clarithromycin together with omeprazole (OAC) or rabeprazole (RAC). CYP2C19*2 and *3, IL1B-511, IL1B-31, IL1B+ 3954 and intron 2 of the IL-1RN genotypes were analyzed by polymerase chain reaction-restriction fragment length polymorphism. The intention-to-treat-based cure rate of the OAC regimen was significantly lower than that of the RAC regimen in the CYP2C19 wild-type homozygotes (P = 0·014). No significant differences in the cure rates were observed among the IL-1RN and the IL-1B genotype groups. The rabeprazole-based triple regimen was better than the omeprazole in Chinese patients with the CYP2C19 extensive metabolizer genotype. The effectiveness of the PPI/AC regimen is unrelated to IL-1B and IL1-RN genetic polymorphism. © 2010 Blackwell Publishing Ltd.

Ethylbenzene induces microsomal oxygen free radical generation: antibody-directed characterization of the responsible cytochrome P450 enzymes.

PubMed

Serron, S C; Dwivedi, N; Backes, W L

2000-05-01

Small aromatic hydrocarbons cause changes in oxidative metabolism by modulating the levels of cytochrome P450 enzymes, with the changes in these enzymes being responsible for qualitative changes in aromatic hydrocarbon metabolism. The goal of this study was to determine if exposure to the small alkylbenzene ethylbenzene (EB) leads to an increase in hepatic free radical production. Male F344 rats were treated with ip injections of EB (10 mmol/kg) and compared to corn oil controls. Hepatic free radical production was examined by measuring the conversion of 2',7'-dichlorofluorescin diacetate (DCFH-DA) to its fluorescent product 2',7'-dichlorofluorescein (DCF). A significant elevation of fluorescent DCF production was observed after treatment with EB, despite the lack of effect on overall cytochrome P450 levels. This process was shown to be inhibitable by metyrapone, an inhibitor of P450. DCF production was also inhibited by catalase, suggesting that hydrogen peroxide (H(2)O(2)) is one of the reactive oxygen intermediates involved in EB-mediated reactive oxygen species (ROS) formation. Interestingly, superoxide dismutase (SOD) did not inhibit DCF production in corn oil-treated rats but was an effective inhibitor in the EB-treated groups. In an effort to determine if the increase in ROS production was related to changes in specific P450 enzymes, DCF production was measured in the presence of anti-CYP2B, anti-CYP2C11, anti-CYP2E1, and anti-CYP3A2 inhibitory antibodies. Anti-CYP2B antibodies inhibited DCF production in EB-treated, but not corn oil groups, which is consistent with the low constitutive levels of this enzyme and its induction by EB. The data also demonstrate that CYP2B contributes to ROS production. Anti-CYP2C11 did not influence DCF production in either group. ROS formation in corn oil-treated rats as well as in ethylbenzene-treated rats was also inhibited with antibodies to anti-CYP2E1 and anti-CYP3A2. These results suggest that CYP2C11 does not appear to influence free radical production and that the increase in free radical production in EB treated rats is consistent with the EB-mediated elevation of CYP2B, CYP 2E1, and CYP3A2. Such alterations in free radical generation in response to hydrocarbon treatment may contribute to the toxicity of these compounds. Copyright 2000 Academic Press.

Monitoring Cyp2b10 mRNA expression at cessation of 2-year carcinogenesis bioassay in mouse liver provides evidence for a carcinogenic mechanism devoid of human relevance: The dalcetrapib experience

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hoflack, J-C.; Mueller, L., E-mail: Lutz.Mueller@roche.com; Fowler, S.

2012-03-15

Introduction: Dalcetrapib is a cholesteryl ester transfer protein (CETP) modulator in clinical assessment for cardiovascular outcome benefits. In compliance with regulatory requirements, dalcetrapib was evaluated in rodent 2-year carcinogenesis bioassays. In the mouse bioassay, male mice demonstrated increased liver weight and statistically increased incidences of hepatocellular adenoma/carcinoma. Hepatic cytochrome p450 (Cyp) 2b10 mRNA induction and increased Cyp2b10 enzyme activity signify activation of hepatic nuclear receptor constitutive androstane receptor (CAR), a widely established promoter of rodent-specific hepatic tumors. We therefore monitored hepatic Cyp2b10 mRNA and its enzyme activity in a subset of dalcetrapib-treated male mice from the bioassay. Methods: Liver samplesmore » were obtained from ∼ 1/3 of male mice from each dose group including vehicle-controls (mean and earliest study day of death 678 and 459 respectively). Quantitative real time PCR (qRT-PCR) was performed to determine Cyp2b10 mRNA expression and Cyp1a-, Cyp2b10- and Cyp3a-selective activities were monitored. Results: Cyp2b10 mRNA was strongly induced by dalcetrapib with an expected wide inter-individual variation (5–1421-fold). Group average fold-induction versus vehicle-controls showed a dose-related increase from 48-fold (250 mg/kg/day) to 160-fold (750 mg/kg/day), which declined slightly at 2000 mg/kg/day (97-fold). Cyp enzyme activities showed approximate doubling of total Cyp P450 content per milligram protein and a 9-fold increase in Cyp2b10-selective pentoxyresorufin O-dealkylase activity (750 mg/kg/day). Discussion: These data from hepatic Cyp2b10 monitoring are strongly suggestive of CAR activation by dalcetrapib, a mechanism devoid of relevance towards hepatocarcinogenesis in humans; results show feasibility of Cyp2b10 as a surrogate marker for this mechanism at cessation of a carcinogenesis bioassay. -- Highlights: ► Liver tumors were induced in male mice by dalcetrapib in a 2-y study (bioassay). ► Cyp2b10 induction typifies activation of nuclear receptor CAR in mouse liver. ► First report of hepatic Cyp2b10 monitoring at the end of a mouse bioassay. ► Cyp2b10 induction supports CAR activation by dalcetrapib in mouse bioassay. ► CAR activation is a mechanism of hepatic tumorigenesis of no relevance to humans.« less

An enhanced in vivo stable isotope labeling by amino acids in cell culture (SILAC) model for quantification of drug metabolism enzymes.

PubMed

MacLeod, A Kenneth; Fallon, Padraic G; Sharp, Sheila; Henderson, Colin J; Wolf, C Roland; Huang, Jeffrey T-J

2015-03-01

Many of the enzymes involved in xenobiotic metabolism are maintained at a low basal level and are only synthesized in response to activation of upstream sensor/effector proteins. This induction can have implications in a variety of contexts, particularly during the study of the pharmacokinetics, pharmacodynamics, and drug-drug interaction profile of a candidate therapeutic compound. Previously, we combined in vivo SILAC material with a targeted high resolution single ion monitoring (tHR/SIM) LC-MS/MS approach for quantification of 197 peptide pairs, representing 51 drug metabolism enzymes (DME), in mouse liver. However, as important enzymes (for example, cytochromes P450 (Cyp) of the 1a and 2b subfamilies) are maintained at low or undetectable levels in the liver of unstimulated metabolically labeled mice, quantification of these proteins was unreliable. In the present study, we induced DME expression in labeled mice through synchronous ligand-mediated activation of multiple upstream nuclear receptors, thereby enhancing signals for proteins including Cyps 1a, 2a, 2b, 2c, and 3a. With this enhancement, 115 unique, lysine-containing, Cyp-derived peptides were detected in the liver of a single animal, as opposed to 56 in a pooled sample from three uninduced animals. A total of 386 peptide pairs were quantified by tHR/SIM, representing 68 Phase I, 30 Phase II, and eight control proteins. This method was employed to quantify changes in DME expression in the hepatic cytochrome P450 reductase null (HRN) mouse. We observed compensatory induction of several enzymes, including Cyps 2b10, 2c29, 2c37, 2c54, 2c55, 2e1, 3a11, and 3a13, carboxylesterase (Ces) 2a, and glutathione S-transferases (Gst) m2 and m3, along with down-regulation of hydroxysteroid dehydrogenases (Hsd) 11b1 and 17b6. Using DME-enhanced in vivo SILAC material with tHR/SIM, therefore, permits the robust analysis of multiple DME of importance to xenobiotic metabolism, with improved utility for the study of drug pharmacokinetics, pharmacodynamics, and of chemically treated and genetically modified mouse models. © 2015 by The American Society for Biochemistry and Molecular Biology, Inc.

Early effects of Lansoprazole orally disintegrating tablets on intragastric pH in CYP2C19 extensive metabolizers

PubMed Central

Yamagishi, Hatsushi; Koike, Tomoyuki; Ohara, Shuichi; Horii, Toru; Kikuchi, Ryousuke; Kobayashi, Shigeyuki; Abe, Yasuhiko; Iijima, Katsunori; Imatani, Akira; Suzuki, Kaori; Hishinuma, Takanori; Goto, Junichi; Shimosegawa, Tooru

2008-01-01

AIM: To compare rabeprazole (RPZ; 10 mg) with Lansoprazole orally disintegrating tablets (LPZ; 30 mg OD) in terms of antisecretory activity and blood drug concentration after a single dose. METHODS: Eight H pylori-negative cytochrome P450 (CYP) 2C19 extensive metabolizers were assigned to receive a single oral dose of RPZ 10 mg or LPZ 30 mg OD. Twelve hour intragastric pH monitoring was performed on the day of treatment. Blood samples were also collected after the administration of each drug. RESULTS: LPZ 30 mg OD induced a significantly earlier rise in blood drug concentration than RPZ 10 mg; consequently, LPZ 30 mg OD induced a significantly earlier rise in median pH in the third and fourth hours of the study. CONCLUSION: In H pylori-negative CYP2C19 extensive metabolizers, LPZ 30 mg OD induced a significantly faster inhibition of gastric acid secretion than RPZ 10 mg. PMID:18395905

Effect of estradiol on apoptosis, proliferation and steroidogenic enzymes in the testes of the toad Rhinella arenarum (Amphibia, Anura).

PubMed

Scaia, María Florencia; Volonteri, María Clara; Czuchlej, Silvia Cristina; Ceballos, Nora Raquel

2015-09-15

Estrogens inhibit androgen production and this negative action on amphibian steroidogenesis could be related to the regulation of steroidogenic enzymes. Estrogens are also involved in the regulation of amphibian spermatogenesis by controlling testicular apoptosis and spermatogonial proliferation. The Bidder's organ (BO) is a structure characteristic from the Bufonidae family and in adult males of Rhinella arenarum it is one of the main sources of plasma estradiol (E2). The purpose of this study is to analyze the effect of E2 on testicular steroidogenic enzymes, apoptosis and proliferation in the toad R. arenarum. For this purpose, testicular fragments were treated during 24h with or without 2 or 20nM of E2. After treatments, the activities of cytochrome P450 17α-hydroxylase-C17-20 lyase (CypP450c17) and 3β-hydroxysteroid dehydrogenase/isomerase (3β-HSD/I) were measured by the transformation of radioactive substrates into products, and CypP450c17 expression was determined by Western blot analysis. Apoptosis in testicular sections was detected with a commercial fluorescent kit based on TUNEL method, and proliferation was evaluated by BrdU incorporation. Results indicate that E2 has no effect on CypP450c17 protein levels or enzymatic activity, while it reduces 3β-HSD/I activity during the post reproductive season. Furthermore, although E2 has no effect on apoptosis during the pre and the post reproductive seasons, it stimulates testicular apoptosis during the reproductive season, mostly in spermatocytes. Finally, E2 has no effect on testicular proliferation all year long. Taken together, these results suggest that E2 is involved in the regulation of testicular steroidogenesis and spermatogenesis. Copyright © 2015 Elsevier Inc. All rights reserved.

Genome-wide identification of 52 cytochrome P450 (CYP) genes in the copepod Tigriopus japonicus and their B[α]P-induced expression patterns.

PubMed

Han, Jeonghoon; Kim, Duck-Hyun; Kim, Hui-Su; Nelson, David R; Lee, Jae-Seong

2017-09-01

Cytochrome P450s (CYPs) are enzymes with a heme-binding domain that are found in all living organisms. CYP enzymes have important roles associated with detoxification of xenobiotics and endogenous compounds (e.g. steroids, fatty acids, and hormones). Although CYP enzymes have been reported in several invertebrates, including insects, little is known about copepod CYPs. Here, we identified the entire repertoire of CYP genes (n=52) from whole genome and transcriptome sequences of the benthic copepod Tigriopus japonicus, including a tandem duplication (CYP3026A3, CYP3026A4, CYP3026A5), and examined patterns of gene expression over various developmental stages and in response to benzo[α]pyrene (B[α]P) exposure. Through phylogenetic analysis, the 52 T. japonicus CYP genes were assigned to five distinct clans: CYP2 (22 genes), CYP3 (19 genes), CYP4 (two genes), CYP20 (one gene), and mitochondrial (eight genes). Developmental stage and gender-specific expression patterns of the 52 T. japonicus CYPs were analyzed. CYP3022A1 was constitutively expressed during all developmental stages. CYP genes in clans 2 and 3 were induced in response to B[α]P, suggesting that these differentially modulated CYP transcripts are likely involved in defense against exposure to B[α]P and other pollutants. This study enhances our understanding of the repertoire of CYP genes in copepods and of their potential role in development and detoxification in copepods. Copyright © 2017 Elsevier Inc. All rights reserved.

Cloning, expression pattern and promoter functional analysis of cyp19a1a gene in miiuy croaker.

PubMed

Huang, Wei; Yang, Pan; Lv, Zhenming; Wu, Changwen; Gui, Jianfang; Lou, Bao

2017-09-05

Gonadal-specific aromatase encoded by cyp19a1a is the important enzyme controlling estrogen biosynthesis in teleosts. In the present study, the cDNA sequence of cyp19a1a was cloned and characterized from miiuy croaker Miichthys miiuy. The cDNA encoded a protein of 519 amino acids with five structural regions. Higher identities of amino acid sequences and conserved structural regions were found between Mmcyp19a1a and other cyp19a1a genes. In addition, Mmcyp19a1a was clustered together with other seawater fishes. Immunohistochemical analysis revealed that Mmcyp19a1a was localized exclusively in the cytoplasmic of thecal and granulosa cells surrounding the oocytes. Both the protein and mRNA levels of Mmcyp19a1a were increased significantly at the stage III follicles (mid-vitellogenic) and then decreased along with vitellogenesis. Interestingly, strong immunoreactive signals were also detected in the supporting cells of connective tissues during ovarian development. A 1777bp promoter fragment of Mmcyp19a1a was also isolated, and functional analysis using an EGFP reporter fusion in zebrafish larvae presented positive signals in the above of yolk sac, where is the region of pronephros and germ plasm occur. The Mmcyp19a1a:EGFP expression pattern was generally consistent with the endogenous cyp19a1a genesis. These results indicate that the Mmcyp19a1a gene plays an important role during vitellogenesis and oocyte maturation. The constructor of Mmcyp19a1a:EGFP may provide a useful tool for genetic analysis of gonad development in teleost. Copyright © 2017 Elsevier B.V. All rights reserved.

The Impact of the Hepatocyte-to-Plasma pH Gradient on the Prediction of Hepatic Clearance and Drug-Drug Interactions for CYP2C9 and CYP3A4 Substrates.

PubMed

Rougée, Luc R A; Mohutsky, Michael A; Bedwell, David W; Ruterbories, Kenneth J; Hall, Stephen D

2017-09-01

Surrogate assays for drug metabolism and inhibition are traditionally performed in buffer systems at pH 7.4, despite evidence that hepatocyte intracellular pH is 7.0. This pH gradient can result in a pK a -dependent change in intracellular/extracellular concentrations for ionizable drugs that could affect predictions of clearance and P450 inhibition. The effect of microsomal incubation pH on in vitro enzyme kinetic parameters for CYP2C9 (diclofenac, (S)-warfarin) and CYP3A4 (midazolam, dextromethorphan, testosterone) substrates, enzyme specific reversible inhibitors (amiodarone, desethylamiodarone, clozapine, nicardipine, fluconazole, fluvoxamine, itraconazole) and a mechanism-based inhibitor (amiodarone) was investigated. Intrinsic clearance through CYP2C9 significantly increased (25% and 50% for diclofenac and (S)-warfarin respectively) at intracellular pH 7.0 compared with traditional pH 7.4. The CYP3A4 substrate dextromethorphan intrinsic clearance was decreased by 320% at pH 7.0, while midazolam and testosterone remained unchanged. Reversible inhibition of CYP2C9 was less potent at pH 7.0 compared with 7.4, while CYP3A4 inhibition potency was variably affected. Maximum enzyme inactivation rate of amiodarone toward CYP2C9 and CYP3A4 decreased at pH 7.0, while the irreversible inhibition constant remained unchanged for CYP2C9, but decreased for CYP3A4 at pH 7.0. Predictions of clearance and drug-drug interactions made through physiologically based pharmacokinetic models were improved with the inclusion of predicted intracellular concentrations based at pH 7.0 and in vitro parameters determined at pH 7.0. No general conclusion on the impact of pH could be made and therefore a recommendation to change buffer pH to 7.0 cannot be made at this time. It is recommended that the appropriate hepatocyte intracellular pH 7.0 be used for in vitro determinations when in vivo predictions are made. Copyright © 2017 by The American Society for Pharmacology and Experimental Therapeutics.

An enlarged, adaptable active site in CYP164 family P450 enzymes, the sole P450 in Mycobacterium leprae.

PubMed

Agnew, Christopher R J; Warrilow, Andrew G S; Burton, Nicholas M; Lamb, David C; Kelly, Steven L; Brady, R Leo

2012-01-01

CYP164 family P450 enzymes are found in only a subset of mycobacteria and include CYP164A1, which is the sole P450 found in Mycobacterium leprae, the causative agent of leprosy. This has previously led to interest in this enzyme as a potential drug target. Here we describe the first crystal structure of a CYP164 enzyme, CYP164A2 from Mycobacterium smegmatis. CYP164A2 has a distinctive, enlarged hydrophobic active site that extends above the porphyrin ring toward the access channels. Unusually, we find that CYP164A2 can simultaneously bind two econazole molecules in different regions of the enlarged active site and is accompanied by the rearrangement and ordering of the BC loop. The primary location is through a classic interaction of the azole group with the porphyrin iron. The second econazole molecule is bound to a unique site and is linked to a tetracoordinated metal ion complexed to one of the heme carboxylates and to the side chains of His 105 and His 364. All of these features are preserved in the closely homologous M. leprae CYP164A1. The computational docking of azole compounds to a homology model of CYP164A1 suggests that these compounds will form effective inhibitors and is supported by the correlation of parallel docking with experimental binding studies of CYP164A2. The binding of econazole to CYP164A2 occurs primarily through the high-spin "open" conformation of the enzyme (K(d) [dissociation constant] of 0.1 μM), with binding to the low-spin "closed" form being significantly hindered (K(d) of 338 μM). These studies support previous suggestions that azole derivatives may provide an effective strategy to improve the treatment of leprosy.

An Enlarged, Adaptable Active Site in CYP164 Family P450 Enzymes, the Sole P450 in Mycobacterium leprae

PubMed Central

Agnew, Christopher R. J.; Warrilow, Andrew G. S.; Burton, Nicholas M.; Lamb, David C.; Kelly, Steven L.

2012-01-01

CYP164 family P450 enzymes are found in only a subset of mycobacteria and include CYP164A1, which is the sole P450 found in Mycobacterium leprae, the causative agent of leprosy. This has previously led to interest in this enzyme as a potential drug target. Here we describe the first crystal structure of a CYP164 enzyme, CYP164A2 from Mycobacterium smegmatis. CYP164A2 has a distinctive, enlarged hydrophobic active site that extends above the porphyrin ring toward the access channels. Unusually, we find that CYP164A2 can simultaneously bind two econazole molecules in different regions of the enlarged active site and is accompanied by the rearrangement and ordering of the BC loop. The primary location is through a classic interaction of the azole group with the porphyrin iron. The second econazole molecule is bound to a unique site and is linked to a tetracoordinated metal ion complexed to one of the heme carboxylates and to the side chains of His 105 and His 364. All of these features are preserved in the closely homologous M. leprae CYP164A1. The computational docking of azole compounds to a homology model of CYP164A1 suggests that these compounds will form effective inhibitors and is supported by the correlation of parallel docking with experimental binding studies of CYP164A2. The binding of econazole to CYP164A2 occurs primarily through the high-spin “open” conformation of the enzyme (Kd [dissociation constant] of 0.1 μM), with binding to the low-spin “closed” form being significantly hindered (Kd of 338 μM). These studies support previous suggestions that azole derivatives may provide an effective strategy to improve the treatment of leprosy. PMID:22037849

Population pharmacokinetic modelling to assess the impact of CYP2D6 and CYP3A metabolic phenotypes on the pharmacokinetics of tamoxifen and endoxifen

PubMed Central

ter Heine, Rob; Binkhorst, Lisette; de Graan, Anne Joy M; de Bruijn, Peter; Beijnen, Jos H; Mathijssen, Ron H J; Huitema, Alwin D R

2014-01-01

Aims Tamoxifen is considered a pro-drug of its active metabolite endoxifen. The major metabolic enzymes involved in endoxifen formation are CYP2D6 and CYP3A. There is considerable evidence that variability in activity of these enzymes influences endoxifen exposure and thereby may influence the clinical outcome of tamoxifen treatment. We aimed to quantify the impact of metabolic phenotype on the pharmacokinetics of tamoxifen and endoxifen. Methods We assessed the CYP2D6 and CYP3A metabolic phenotypes in 40 breast cancer patients on tamoxifen treatment with a single dose of dextromethorphan as a dual phenotypic probe for CYP2D6 and CYP3A. The pharmacokinetics of dextromethorphan, tamoxifen and their relevant metabolites were analyzed using non-linear mixed effects modelling. Results Population pharmacokinetic models were developed for dextromethorphan, tamoxifen and their metabolites. In the final model for tamoxifen, the dextromethorphan derived metabolic phenotypes for CYP2D6 as well as CYP3A significantly (P < 0.0001) explained 54% of the observed variability in endoxifen formation (inter-individual variability reduced from 55% to 25%). Conclusions We have shown that not only CYP2D6, but also CYP3A enzyme activity influences the tamoxifen to endoxifen conversion in breast cancer patients. Our developed model may be used to assess separately the impact of CYP2D6 and CYP3A mediated drug–drug interactions with tamoxifen without the necessity of administering this anti-oestrogenic drug and to support Bayesian guided therapeutic drug monitoring of tamoxifen in routine clinical practice. PMID:24697814

Drug-Induced Gingival Overgrowth: The Genetic Dimension

PubMed Central

Charles, Noronha Shyam Curtis; Chavan, Rahul; Moon, Ninad Joshirao; Nalla, Srinivas; Mali, Jaydeepchandra; Prajapati, Anchal

2014-01-01

Background: Currently, the etiology of drug-induced gingival overgrowth is not entirely understood but is clearly multifactorial. Phenytoin, one of the common drugs implicated in gingival enlargement, is metabolized mainly by cytochrome P450 (CYP)2C9 and partly by CYP2C19. The CYP2C9 and CYP2C19 genes are polymorphically expressed and most of the variants result in decreased metabolism of the respective substrates. Aims: The present study was undertaken to investigate the influence of the CYP2C9*2 and *3 variant genotypes on phenytoin hydroxylation in subjects diagnosed with epilepsy from South India, thus establishing the genetic polymorphisms leading to its defective hydroxylation process. Materials and Methods: Fifteen epileptic subjects, age 9 to 60 years were included in the study. Among the study subjects, 8 were males and 7 were females. Genomic DNA was extracted from patients’ blood using Phenol-chloroform method and genotyping was done for CYP2C9 using customized TaqMan genotyping assays on a real time thermocycler, by allelic discrimination method. The genetic polymorphisms *1, *2 and *3 on CYP2C9 were selected based on their function and respective allele frequencies in Asian subcontinent among the Asian populations. Results: CYP2C9*1*2 and CYP2C9*3/*3 were identified with equal frequency in the study population. There were seven subjects with CYP2C9*1/*2 genotype (heterozygous mutant), one subject with CYP2C9*1/*1 (wild type) and seven study subjects with CYP2C9*3/*3 (homozygous mutant). Conclusion: The results obtained in the present study will be helpful in the medical prescription purposes of phenytoin, and a more personalized patient approach with its administration can be advocated. PMID:25317394

Drug-induced gingival overgrowth: the genetic dimension.

PubMed

Charles, Noronha Shyam Curtis; Chavan, Rahul; Moon, Ninad Joshirao; Nalla, Srinivas; Mali, Jaydeepchandra; Prajapati, Anchal

2014-09-01

Currently, the etiology of drug-induced gingival overgrowth is not entirely understood but is clearly multifactorial. Phenytoin, one of the common drugs implicated in gingival enlargement, is metabolized mainly by cytochrome P450 (CYP)2C9 and partly by CYP2C19. The CYP2C9 and CYP2C19 genes are polymorphically expressed and most of the variants result in decreased metabolism of the respective substrates. The present study was undertaken to investigate the influence of the CYP2C9*2 and *3 variant genotypes on phenytoin hydroxylation in subjects diagnosed with epilepsy from South India, thus establishing the genetic polymorphisms leading to its defective hydroxylation process. Fifteen epileptic subjects, age 9 to 60 years were included in the study. Among the study subjects, 8 were males and 7 were females. Genomic DNA was extracted from patients' blood using Phenol-chloroform method and genotyping was done for CYP2C9 using customized TaqMan genotyping assays on a real time thermocycler, by allelic discrimination method. The genetic polymorphisms *1, *2 and *3 on CYP2C9 were selected based on their function and respective allele frequencies in Asian subcontinent among the Asian populations. CYP2C9*1*2 and CYP2C9*3/*3 were identified with equal frequency in the study population. There were seven subjects with CYP2C9*1/*2 genotype (heterozygous mutant), one subject with CYP2C9*1/*1 (wild type) and seven study subjects with CYP2C9*3/*3 (homozygous mutant). The results obtained in the present study will be helpful in the medical prescription purposes of phenytoin, and a more personalized patient approach with its administration can be advocated.

Differential effects of nicotine treatment and ethanol self-administration on CYP2A6, CYP2B6 and nicotine pharmacokinetics in African green monkeys.

PubMed

Ferguson, C S; Miksys, S; Palmour, R M; Tyndale, R F

2012-12-01

In primates, nicotine is metabolically inactivated in the liver by CYP2A6 and possibly CYP2B6. Changes in the levels of these two enzymes may affect nicotine pharmacokinetics and influence smoking behaviors. This study investigated the independent and combined effects of ethanol self-administration and nicotine treatment (0.5 mg/kg b.i.d. s.c.) on hepatic CYP2A6 and CYP2B6 levels (mRNA, protein, and enzymatic activity), in vitro nicotine metabolism, and in vivo nicotine pharmacokinetics in monkeys. CYP2A6 mRNA and protein levels and in vitro coumarin (selective CYP2A6 substrate) and nicotine metabolism were decreased by nicotine treatment but unaffected by ethanol. CYP2B6 protein levels and in vitro bupropion (selective CYP2B6 substrate) metabolism were increased by ethanol but unaffected by nicotine treatment; CYP2B6 mRNA levels were unaltered by either treatment. Combined ethanol and nicotine exposure decreased CYP2A6 mRNA and protein levels, as well as in vitro coumarin and nicotine metabolism, and increased CYP2B6 protein levels and in vitro bupropion metabolism, with no change in CYP2B6 mRNA levels. Chronic nicotine resulted in higher nicotine plasma levels achieved after nicotine administration, consistent with decreased CYP2A6. Ethanol alone, or combined with nicotine, resulted in lower nicotine plasma levels by a mechanism independent of the change in these enzymes. Thus, nicotine can decrease hepatic CYP2A6, reducing the metabolism of its substrates, including nicotine, whereas ethanol can increase hepatic CYP2B6, increasing the metabolism of CYP2B6 substrates. In vivo nicotine pharmacokinetics are differentially affected by ethanol and nicotine, but when both drugs are used in combination the effect more closely resembles ethanol alone.

Expression and activity profiling of the steroidogenic enzymes of glucocorticoid biosynthesis and the fdx1 co-factors in zebrafish.

PubMed

Weger, M; Diotel, N; Weger, B D; Beil, T; Zaucker, A; Eachus, H L; Oakes, J A; do Rego, J L; Storbeck, K-H; Gut, P; Strähle, U; Rastegar, S; Müller, F; Krone, N

2018-04-01

The spatial and temporal expression of steroidogenic genes in zebrafish has not been fully characterised. Because zebrafish are increasingly employed in endocrine and stress research, a better characterisation of steroidogenic pathways is required to target specific steps in the biosynthetic pathways. In the present study, we have systematically defined the temporal and spatial expression of steroidogenic enzymes involved in glucocorticoid biosynthesis (cyp21a2, cyp11c1, cyp11a1, cyp11a2, cyp17a1, cyp17a2, hsd3b1, hsd3b2), as well as the mitochondrial electron-providing ferredoxin co-factors (fdx1, fdx1b), during zebrafish development. Our studies showed an early expression of all these genes during embryogenesis. In larvae, expression of cyp11a2, cyp11c1, cyp17a2, cyp21a2, hsd3b1 and fdx1b can be detected in the interrenal gland, which is the zebrafish counterpart of the mammalian adrenal gland, whereas the fdx1 transcript is mainly found in the digestive system. Gene expression studies using quantitative reverse transcriptase-PCR and whole-mount in situ hybridisation in the adult zebrafish brain revealed a wide expression of these genes throughout the encephalon, including neurogenic regions. Using ultra-high-performance liquid chromatography tandem mass spectrometry, we were able to demonstrate the presence of the glucocorticoid cortisol in the adult zebrafish brain. Moreover, we demonstrate de novo biosynthesis of cortisol and the neurosteroid tetrahydrodeoxycorticosterone in the adult zebrafish brain from radiolabelled pregnenolone. Taken together, the present study comprises a comprehensive characterisation of the steroidogenic genes and the fdx co-factors facilitating glucocorticoid biosynthesis in zebrafish. Furthermore, we provide additional evidence of de novo neurosteroid biosynthesising in the brain of adult zebrafish facilitated by enzymes involved in glucocorticoid biosynthesis. Our study provides a valuable source for establishing the zebrafish as a translational model with respect to understanding the roles of the genes for glucocorticoid biosynthesis and fdx co-factors during embryonic development and stress, as well as in brain homeostasis and function. © 2018 British Society for Neuroendocrinology.

Comparison of acid inhibition with standard dosages of proton pump inhibitors in relation to CYP2C19 genotype in Japanese.

PubMed

Sugimoto, Mitsushige; Shirai, Naohito; Nishino, Masafumi; Kodaira, Chise; Uotani, Takahiro; Sahara, Shu; Ichikawa, Hitomi; Kagami, Takuma; Sugimoto, Ken; Furuta, Takahisa

2014-09-01

The aim of therapeutic regimens using proton pump inhibitors (PPIs) in patients with acid-related diseases is to potently inhibit acid secretion for the full 24 h. However, optimum treatment is still unclear because the pharmacodynamics of PPIs differ among CYP2C19 genotypes and most of the previous studies have had loss of sample power. Using pH monitoring, we compared acid inhibition at standard dosage of omeprazole (20 mg, 50 times), lansoprazole (30 mg, 68 times), and rabeprazole (10 mg, 65 times) in Helicobacter pylori-negative healthy young Japanese volunteers. Median pH with rabeprazole was 5.4 (3.3-7.5), which was significantly greater than with either omeprazole [4.4 (2.1-7.3)] or lansoprazole [4.8 (3.5-6.4)] (both P < 0.05). Median 24-h pH differed among the different CYP2C19 genotypes in all three PPIs. In CYP2C19 extensive metabolizers (EMs), the genotype that is refractory to PPI treatment, median pH with omeprazole, lansoprazole, and rabeprazole was 3.8 (2.1-4.4), 4.5 (3.5-5.3) and 4.8 (3.3-7.5), respectively. Treatment with the selected PPIs at their standard dosages had difficulty maintaining acid inhibition for a full 24 h, especially in CYP2C19 EM. However, rabeprazole has the merit of less influence of CYP2C19 genotype compared with the other PPIs.

Involvement of ERK1/2 signaling pathway in atrazine action on FSH-stimulated LHR and CYP19A1 expression in rat granulosa cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Fa, Svetlana; Pogrmic-Majkic, Kristina; Samardzija, Dragana

Worldwide used herbicide atrazine is linked to reproductive dysfunction in females. In this study, we investigated the effects and the mechanism of atrazine action in the ovary using a primary culture of immature granulosa cells. In granulosa cells, follicle-stimulating hormone (FSH) activates both cyclic adenosine monophosphate (cAMP) and extracellular-regulated kinase 1/2 (ERK1/2) cascades, with cAMP pathway being more important for luteinizing hormone receptor (LHR) and aromatase (CYP19A1) mRNA expression. We report that 48 h after atrazine exposure the FSH-stimulated LHR and CYP19A1 mRNA expression and estradiol synthesis were decreased, with LHR mRNA being more sensitive to atrazine than CYP19A1 mRNA.more » Inadequate acquisition of LHR in the FSH-stimulated and atrazine-exposed granulosa cells renders human chorionic gonadotropin (hCG) ineffective to stimulate amphiregulin (Areg), epiregulin (Ereg), and progesterone receptor (Pgr) mRNA expression, suggesting anti-ovulatory effect of atrazine. To dissect the signaling cascade involved in atrazine action in granulosa cells, we used U0126, a pharmacological inhibitor of ERK1/2. U0126 prevents atrazine-induced decrease in LHR and CYP19A1 mRNA levels and estradiol production in the FSH-stimulated granulosa cells. ERK1/2 inactivation restores the ability of hCG to induce expression of the ovulatory genes in atrazine-exposed granulosa cells. Cell-based ELISA assay revealed that atrazine does not change the FSH-stimulated ERK1/2 phosphorylation in granulosa cells. The results from this study reveal that atrazine does not affect but requires ERK1/2 phosphorylation to cause decrease in the FSH-induced LHR and CYP19A1 mRNA levels and estradiol production in immature granulosa cells, thus compromising ovulation and female fertility. - Highlights: • Atrazine inhibits estradiol production in FSH-stimulated granulosa cells. • Atrazine inhibits LHR and Cyp19a1 mRNA expression in FSH-stimulated granulosa cells. • Atrazine prevents hCG-induced expression of the ovulatory genes. • ERK1/2 activation is required for atrazine action in granulosa cells. • Atrazine does not interfere with FSH-stimulated ERK1/2 phosphorylation.« less

Predicting CYP2C19 Catalytic Parameters for Enantioselective Oxidations Using Artificial Neural Networks and a Chirality Code

PubMed Central

Hartman, Jessica H.; Cothren, Steven D.; Park, Sun-Ha; Yun, Chul-Ho; Darsey, Jerry A.; Miller, Grover P.

2013-01-01

Cytochromes P450 (CYP for isoforms) play a central role in biological processes especially metabolism of chiral molecules; thus, development of computational methods to predict parameters for chiral reactions is important for advancing this field. In this study, we identified the most optimal artificial neural networks using conformation-independent chirality codes to predict CYP2C19 catalytic parameters for enantioselective reactions. Optimization of the neural networks required identifying the most suitable representation of structure among a diverse array of training substrates, normalizing distribution of the corresponding catalytic parameters (kcat, Km, and kcat/Km), and determining the best topology for networks to make predictions. Among different structural descriptors, the use of partial atomic charges according to the CHelpG scheme and inclusion of hydrogens yielded the most optimal artificial neural networks. Their training also required resolution of poorly distributed output catalytic parameters using a Box-Cox transformation. End point leave-one-out cross correlations of the best neural networks revealed that predictions for individual catalytic parameters (kcat and Km) were more consistent with experimental values than those for catalytic efficiency (kcat/Km). Lastly, neural networks predicted correctly enantioselectivity and comparable catalytic parameters measured in this study for previously uncharacterized CYP2C19 substrates, R- and S-propranolol. Taken together, these seminal computational studies for CYP2C19 are the first to predict all catalytic parameters for enantioselective reactions using artificial neural networks and thus provide a foundation for expanding the prediction of cytochrome P450 reactions to chiral drugs, pollutants, and other biologically active compounds. PMID:23673224

A randomized open trial for comparison of proton pump inhibitors, omeprazole versus rabeprazole, in dual therapy for Helicobacter pylori infection in relation to CYP2C19 genetic polymorphism.

PubMed

Miyoshi, M; Mizuno, M; Ishiki, K; Nagahara, Y; Maga, T; Torigoe, T; Nasu, J; Okada, H; Yokota, K; Oguma, K; Tsuji, T

2001-07-01

The genetic polymorphism of cytochrome P450 (CYP) 2C19 has been shown to influence the efficacy of Helicobacter pylori eradication therapy with a proton pump inhibitor (PPI) and amoxicillin (so-called dual therapy). Omeprazole, a widely used PPI, and rabeprazole, a new PPI, are metabolized in different pathways in terms of CYP2C19 genetic polymorphisms. In this study, we compared the efficacy of omeprazole and rabeprazole in a 2-week dual therapy in relation to CYP2C19 polymorphism. One hundred and ninety-nine patients with peptic ulcer disease were randomly assigned to receive one of the following regimens: 500 mg t.i.d. amoxicillin together with either 20 mg b.i.d. omeprazole or 10 mg b.i.d rabeprazole. The eradication of H. pylori was evaluated by using a bacterial culture and a [(13)C]-urea breath test at 1--2 months after completion of treatment. Cytochrome P4502C19 polymorphism was analyzed by using polymerase chain reaction-restriction fragment length polymorphism. Intention-to-treat-based cure rates for the omeprazole or rabeprazole regimens were 66.3% (95% CI, 56--75) and 62.4% (95% CI, 52--71), respectively, without significant difference. Cytochrome P4502C19 genetic polymorphism did not influence the cure rates in either of these regimens. We analyzed various factors associated with treatment failure (PPI, CYP2C19 genotype, and smoking habit) by using multiple logistic regression; smoking was the only significant independent factor for treatment failure. Omeprazole and rabeprazole were equally effective in combination with amoxicillin in eradicating H. pylori, irrespective of the PPI used (omeprazole or rabeprazole) and CYP2C19 genetic polymorphism. Smoking significantly decreased the cure rate of H. pylori infection in the dual therapy.

Up-regulation of CYP1A1 and phase II enzymes by 5-ring isomeric polycyclic aromatic hydrocarbons in precision-cut rat hepatic slices: Importance of molecular shape.

PubMed

Pushparajah, Daphnee; Lewis, Dfv; Ioannides, Costas

2017-04-01

The objectives of the present study were two-fold: (a) to evaluate the role of molecular shape on the interaction of polycyclic aromatic hydrocarbons (PAHs) with the Ah receptor and CYP1A1 upregulation, and (b) to evaluate the potential of PAHs to induce epoxide hydrolase and glutathione S-transferase, two major enzymes involved in their metabolism. In order to achieve these objectives, precision-cut rat liver slices were incubated with a range of concentrations of seven 5-ring isomeric PAHs, namely benzo[c]chrysene, benzo[b]chrysene, benzo[g]chrysene, dibenzo[a,j]anthracene, dibenzo[a,c]anthracene, picene and pentacene, for 24h. All compounds, with the exception of pentacene, elevated the O-deethylation of ethoxyresorufin, an activity associated with CYP1A1; induction of this enzyme by the various PAHs correlated with their avidity for the Ah receptor. None of the PAHs studied increased epoxide hydrolase activity, monitored using benzo[a]pyrene 4,5-oxide. Of the seven PAHs, only benzo[g]chrysene elevated glutathione S-transferase activity, measured using 1-chloro-2,4-dinitrobenzene or 7-chloro-4-nitrobenzo-2-oxa-1,3-diazole as substrates. No relationship could be established between length or length/width and interaction with the Ah receptor and CYP1A1 up-regulation indicating that other structural or electronic factors are likely to be more important. Finally, 5-ring PAHs are poor inducers of the epoxide hydrolase and glutathione S-transferase enzyme systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

[Interaction between CYP450 enzymes and metabolism of traditional Chinese medicine as well as enzyme activity assay].

PubMed

Lu, Tu-lin; Su, Lian-lin; Ji, De; Gu, Wei; Mao, Chun-qin

2015-09-01

Drugs are exogenous compounds for human bodies, and will be metabolized by many enzymes after administration. CYP450 enzyme, as a major metabolic enzyme, is an important phase I drug metabolizing enzyme. In human bodies, about 75% of drug metabolism is conducted by CYP450 enzymes, and CYP450 enzymes is the key factor for drug interactions between traditional Chinese medicine( TCM) -TCM, TCM-medicine and other drug combination. In order to make clear the interaction between metabolic enzymes and TCM metabolism, we generally chose the enzymatic activity as an evaluation index. That is to say, the enhancement or reduction of CYP450 enzyme activity was used to infer the inducing or inhibitory effect of active ingredients and extracts of traditional Chinese medicine on enzymes. At present, the common method for measuring metabolic enzyme activity is Cocktail probe drugs, and it is the key to select the suitable probe substrates. This is of great significance for study drug's absorption, distribution, metabolism and excretion (ADME) process in organisms. The study focuses on the interaction between TCMs, active ingredients, herbal extracts, cocktail probe substrates as well as CYP450 enzymes, in order to guide future studies.

Cytochrome P450 2C8 pharmacogenetics: a review of clinical studies

PubMed Central

Daily, Elizabeth B; Aquilante, Christina L

2009-01-01

Cytochrome P450 (CYP) 2C8 is responsible for the oxidative metabolism of many clinically available drugs from a diverse number of drug classes (e.g., thiazolidinediones, meglitinides, NSAIDs, antimalarials and chemotherapeutic taxanes). The CYP2C8 enzyme is encoded by the CYP2C8 gene, and several common nonsynonymous polymorphisms (e.g., CYP2C8*2 and CYP2C8*3) exist in this gene. The CYP2C8*2 and *3 alleles have been associated in vitro with decreased metabolism of paclitaxel and arachidonic acid. Recently, the influence of CYP2C8 polymorphisms on substrate disposition in humans has been investigated in a number of clinical pharmacogenetic studies. Contrary to in vitro data, clinical data suggest that the CYP2C8*3 allele is associated with increased metabolism of the CYP2C8 substrates, rosiglitazone, pioglitazone and repaglinide. However, the CYP2C8*3 allele has not been associated with paclitaxel pharmacokinetics in most clinical studies. Furthermore, clinical data regarding the impact of the CYP2C8*3 allele on the disposition of NSAIDs are conflicting and no definitive conclusions can be made at this time. The purpose of this review is to highlight these clinical studies that have investigated the association between CYP2C8 polymorphisms and CYP2C8 substrate pharmacokinetics and/or pharmacodynamics in humans. In this review, CYP2C8 clinical pharmacogenetic data are provided by drug class, followed by a discussion of the future of CYP2C8 clinical pharmacogenetic research. PMID:19761371

A Rapid and Accurate Method to Evaluate Helicobacter pylori Infection, Clarithromycin Resistance, and CYP2C19 Genotypes Simultaneously From Gastric Juice

PubMed Central

Kuo, Chao-Hung; Liu, Chung-Jung; Yang, Ching-Chia; Kuo, Fu-Chen; Hu, Huang-Ming; Shih, Hsiang-Yao; Wu, Meng-Chieh; Chen, Yen-Hsu; Wang, Hui-Min David; Ren, Jian-Lin; Wu, Deng-Chyang; Chang, Lin-Li

2016-01-01

Abstract Because Helicobacter pylori (H pylori) would cause carcinogenesis of the stomach, we need sufficient information for deciding on an appropriate strategy of eradication. Many factors affect the efficacy of eradication including antimicrobial resistance (especially clarithromycin resistance) and CYP2C19 polymorphism. This study was to survey the efficiency of gastric juice for detecting H pylori infection, clarithromycin resistance, and CYP2C19 polymorphism. The specimens of gastric juice were collected from all patients while receiving gastroscopy. DNA was extracted from gastric juice and then urease A and cag A were amplified by polymerase chain reaction (PCR) for detecting the existence of H pylori. By PCR-restriction fragment length polymorphism (PCR-RFLP), the 23S rRNA of H pylori and CYP2C19 genotypes of host were examined respectively. During endoscopy examination, biopsy-based specimens were also collected for rapid urease test, culture, and histology. The blood samples were also collected for analysis of CYP2C19 genotypes. We compared the results of gastric juice tests with the results of traditional clinical tests. When compared with the results from traditional clinical tests, our results from gastric juice showed that the sensitivity (SEN), specificity (SPE), positive predictive value (PPV), negative predictive value (NPV), and accuracy to detect H pylori infection were 92.1% (105/114), 92.9% (143/154), 90.5% (105/116), 94.1% (143/152), and 92.5% (248/268), respectively. The SEN, SPE, PPV, and NPV to detect clarithromycin resistance were 97.3% (36/37), 91.5% (43/47), 90.0% (36/40), and 97.7% (43/44), respectively. By using PCR-RFLP, the consistency of human CYP2C19 gene polymorphism from blood samples and gastric juice was as high as 94.9% (149/157). The manipulated gastric juice is actually an effective diagnostic sample for evaluation of H pylori existence, clarithromycin resistance, and host CYP2C19 polymorphism. PMID:27227911

Independent and combined effects of environmental factors and CYP2C19 polymorphisms on the risk of esophageal squamous cell carcinoma in Fujian Province of China.

PubMed

Peng, Xian-E; Chen, Hua-Fang; Hu, Zhi-Jian; Shi, Xi-Shun

2015-03-17

The purpose of this study was to explore the effects of CYP2C19 gene polymorphisms and various environmental factors and their interactions on the risk of esophageal squamous cell carcinoma (ESCC) in a Chinese Han population. A 1:2 frequency-matched case control study of 285 patients and 570 controls was conducted from June 2010 to May 2011 in AnXi of Fujian province, China. Environmental factors were investigated using a self-administered questionnaire and genotypes were determined using polymerase chain reaction restriction fragment length polymorphism based methods. Unconditional logistic regression models were used for statistical evaluation. Current or former smoking, consumption of pickled vegetables or hot beverages/food, having a first degree relative with ESCC and history of reflux esophagitis were significantly associated with increased ESCC risk, whereas tea drinking and consumption of fresh vegetables and fruits were significantly associated with decreased risk. The CYP2C19*2 GA/AA genotype was significantly more prevalent in ESCC patients and individuals with at least one copy of the CYP2C19*2 A allele had a 3.19-fold increased risk (adjusted 95% confidence interval (CI): 2.21-4.61, P < 0.001) of ESCC compared with those without this allele. We found no significant associations between CYP2C19*3 genotypes and ESCC. The Cyp2C19*2 polymorphism appeared to have a multiplicative joint effect with tea drinking and hot beverage/food consumption (gene-tea drinking: P(interaction) = 0.042; hot beverage/food consumption: P(interaction) = 6.98 × 10(-6)) and an additive joint effect with pickled vegetable consumption (interaction contrast ratio = 1.96, 95% CI: 0.12-3.80). Our findings suggest that the CYP2C19*2 polymorphism plays an important role in the development of ESCC in the Chinese population, modified by tea drinking and consumption of pickled vegetables or hot beverages/food. Further studies are warranted to confirm our results.

Predictors of Variation in CYP2A6 mRNA, Protein, and Enzyme Activity in a Human Liver Bank: Influence of Genetic and Nongenetic Factors.

PubMed

Tanner, Julie-Anne; Prasad, Bhagwat; Claw, Katrina G; Stapleton, Patricia; Chaudhry, Amarjit; Schuetz, Erin G; Thummel, Kenneth E; Tyndale, Rachel F

2017-01-01

Cytochrome P450 2A6 CYP2A6: metabolizes several clinically relevant substrates, including nicotine, the primary psychoactive component in cigarette smoke. Smokers vary widely in their rate of inactivation and clearance of nicotine, altering numerous smoking phenotypes. We aimed to characterize independent and shared impact of genetic and nongenetic sources of variation in CYP2A6 mRNA, protein, and enzyme activity in a human liver bank (n = 360). For the assessment of genetic factors, we quantified levels of CYP2A6, cytochrome P450 oxidoreductase (POR), and aldo-keto reductase 1D1 (AKR1D1) mRNA, and CYP2A6 and POR proteins. CYP2A6 enzyme activity was determined through measurement of cotinine formation from nicotine and 7-hydroxycoumarin formation from coumarin. Donor DNA was genotyped for CYP2A6, POR, and AKR1D1 genetic variants. Nongenetic factors assessed included gender, age, and liver disease. CYP2A6 phenotype measures were positively correlated to each other (r values ranging from 0.47-0.88, P < 0.001). Female donors exhibited higher CYP2A6 mRNA expression relative to males (P < 0.05). Donor age was weakly positively correlated with CYP2A6 protein (r = 0.12, P < 0.05) and activity (r = 0.20, P < 0.001). CYP2A6 reduced-function genotypes, but not POR or AKR1D1 genotypes, were associated with lower CYP2A6 protein (P < 0.001) and activity (P < 0.01). AKR1D1 mRNA was correlated with CYP2A6 mRNA (r = 0.57, P < 0.001), protein (r = 0.30, P < 0.001), and activity (r = 0.34, P < 0.001). POR protein was correlated with CYP2A6 activity (r = 0.45, P < 0.001). Through regression analyses, we accounted for 17% (P < 0.001), 37% (P < 0.001), and 77% (P < 0.001) of the variation in CYP2A6 mRNA, protein, and activity, respectively. Overall, several independent and shared sources of variation in CYP2A6 activity in vitro have been identified, which could translate to variable hepatic clearance of nicotine. Copyright © 2016 by The American Society for Pharmacology and Experimental Therapeutics.

Equine cytochrome P450 2B6 — Genomic identification, expression and functional characterization with ketamine

DOE Office of Scientific and Technical Information (OSTI.GOV)

Peters, L.M.; Demmel, S.; Pusch, G.

2013-01-01

Ketamine is an anesthetic and analgesic regularly used in veterinary patients. As ketamine is almost always administered in combination with other drugs, interactions between ketamine and other drugs bear the risk of either adverse effects or diminished efficacy. Since cytochrome P450 enzymes (CYPs) play a pivotal role in the phase I metabolism of the majority of all marketed drugs, drug–drug interactions often occur at the active site of these enzymes. CYPs have been thoroughly examined in humans and laboratory animals, but little is known about equine CYPs. The characterization of equine CYPs is essential for a better understanding of drugmore » metabolism in horses. We report annotation, cloning and heterologous expression of the equine CYP2B6 in V79 Chinese hamster fibroblasts. After computational annotation of all CYP2B genes, the coding sequence (CDS) of equine CYP2B6 was amplified by RT-PCR from horse liver total RNA and revealed an amino acid sequence identity of 77% and a similarity of 93.7% to its human ortholog. A non-synonymous variant c.226G>A in exon 2 of the equine CYP2B6 was detected in 97 horses. The mutant A-allele showed an allele frequency of 82%. Two further variants in exon 3 were detected in one and two horses of this group, respectively. Transfected V79 cells were incubated with racemic ketamine and norketamine as probe substrates to determine metabolic activity. The recombinant equine CYP2B6 N-demethylated ketamine to norketamine and produced metabolites of norketamine, such as hydroxylated norketamines and 5,6-dehydronorketamine. V{sub max} for S-/and R-norketamine formation was 0.49 and 0.45 nmol/h/mg cellular protein and K{sub m} was 3.41 and 2.66 μM, respectively. The N-demethylation of S-/R-ketamine was inhibited concentration-dependently with clopidogrel showing an IC{sub 50} of 5.63 and 6.26 μM, respectively. The functional importance of the recorded genetic variants remains to be explored. Equine CYP2B6 was determined to be a CYP enzyme involved in ketamine and norketamine metabolism, thus confirming results from inhibition studies with horse liver microsomes. Clopidogrel seems to be a feasible inhibitor for equine CYP2B6. The specificity still needs to be established with other single equine CYPs. Heterologous expression of single equine CYP enzymes opens new possibilities to substantially improve the understanding of drug metabolism and drug interactions in horses. -- Highlights: ► We annotate, express and functionally characterize equine CYP2B6. ► 3 genetic variants within this gene are described. ► Equine CYP2B6 N-demethylates ketamine and metabolizes norketamine. ► Equine CYP2B6 can be inhibited by clopidogrel.« less

New Psychoactive Substances 3-Methoxyphencyclidine (3-MeO-PCP) and 3-Methoxyrolicyclidine (3-MeO-PCPy): Metabolic Fate Elucidated with Rat Urine and Human Liver Preparations and their Detectability in Urine by GC-MS, "LC-(High Resolution)-MSn" and "LC-(High Resolution)-MS/MS".

PubMed

A Michely, Julian A; Manier, Sascha K; Caspar, Achim T; Brandt, Simon D; Wallach, Jason; Maurer, Hans H

2017-01-01

3-Methoxyphencyclidine (3-MeO-PCP) and 3-methoxyrolicyclidine (3-MeOPCPy) are two new psychoactive substances (NPS). The aims of the present study were the elucidation of their metabolic fate in rat and pooled human liver microsomes (pHLM), the identification of the cytochrome P450 (CYP) isoenzymes involved, and the detectability using standard urine screening approaches (SUSA) after intake of common users' doses using gas chromatography-mass spectrometry (GC-MS), liquid chromatography-multi-stage mass spectrometry (LC-MSn), and liquid chromatography-high-resolution tandem mass spectrometry (LC-HR-MS/MS). For metabolism studies, rat urine samples were treated by solid phase extraction or simple precipitation with or without previous enzymatic conjugate cleavage. After analyses via LC-HR-MSn, the phase I and II metabolites were identified. Both drugs showed multiple aliphatic hydroxylations at the cyclohexyl ring and the heterocyclic ring, single aromatic hydroxylation, carboxylation after ring opening, O-demethylation, and glucuronidation. The transferability from rat to human was investigated by pHLM incubations, where Odemethylation and hydroxylation were observed. The involvement of the individual CYP enzymes in the initial metabolic steps was investigated after single CYP incubations. For 3-MeO-PCP, CYP 2B6 was responsible for aliphatic hydroxylations and CYP 2C19 and CYP 2D6 for O-demethylation. For 3-MeO-PCPy, aliphatic hydroxylation was again catalyzed by CYP 2B6 and O-demethylation by CYP 2C9 and CYP 2D6 Conclusions: As only polymorphically expressed enzymes were involved, pharmacogenomic variations might occur, but clinical data are needed to confirm the relevance. The detectability studies showed that the authors' SUSAs were suitable for monitoring the intake of both drugs using the identified metabolites. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Structural analyses of Candida albicans sterol 14α-demethylase complexed with azole drugs address the molecular basis of azole-mediated inhibition of fungal sterol biosynthesis

PubMed Central

Hargrove, Tatiana Y.; Friggeri, Laura; Wawrzak, Zdzislaw; Qi, Aidong; Hoekstra, William J.; Schotzinger, Robert J.; York, John D.; Guengerich, F. Peter; Lepesheva, Galina I.

2017-01-01

With some advances in modern medicine (such as cancer chemotherapy, broad exposure to antibiotics, and immunosuppression), the incidence of opportunistic fungal pathogens such as Candida albicans has increased. Cases of drug resistance among these pathogens have become more frequent, requiring the development of new drugs and a better understanding of the targeted enzymes. Sterol 14α-demethylase (CYP51) is a cytochrome P450 enzyme required for biosynthesis of sterols in eukaryotic cells and is the major target of clinical drugs for managing fungal pathogens, but some of the CYP51 key features important for rational drug design have remained obscure. We report the catalytic properties, ligand-binding profiles, and inhibition of enzymatic activity of C. albicans CYP51 by clinical antifungal drugs that are used systemically (fluconazole, voriconazole, ketoconazole, itraconazole, and posaconazole) and topically (miconazole and clotrimazole) and by a tetrazole-based drug candidate, VT-1161 (oteseconazole: (R)-2-(2,4-difluorophenyl)-1,1-difluoro-3-(1H-tetrazol-1-yl)-1-(5-(4-(2,2,2-trifluoroethoxy)phenyl)pyridin-2-yl)propan-2-ol). Among the compounds tested, the first-line drug fluconazole was the weakest inhibitor, whereas posaconazole and VT-1161 were the strongest CYP51 inhibitors. We determined the X-ray structures of C. albicans CYP51 complexes with posaconazole and VT-1161, providing a molecular mechanism for the potencies of these drugs, including the activity of VT-1161 against Candida krusei and Candida glabrata, pathogens that are intrinsically resistant to fluconazole. Our comparative structural analysis outlines phylum-specific CYP51 features that could direct future rational development of more efficient broad-spectrum antifungals. PMID:28258218

Structural analyses of Candida albicans sterol 14α-demethylase complexed with azole drugs address the molecular basis of azole-mediated inhibition of fungal sterol biosynthesis.

PubMed

Hargrove, Tatiana Y; Friggeri, Laura; Wawrzak, Zdzislaw; Qi, Aidong; Hoekstra, William J; Schotzinger, Robert J; York, John D; Guengerich, F Peter; Lepesheva, Galina I

2017-04-21

With some advances in modern medicine (such as cancer chemotherapy, broad exposure to antibiotics, and immunosuppression), the incidence of opportunistic fungal pathogens such as Candida albicans has increased. Cases of drug resistance among these pathogens have become more frequent, requiring the development of new drugs and a better understanding of the targeted enzymes. Sterol 14α-demethylase (CYP51) is a cytochrome P450 enzyme required for biosynthesis of sterols in eukaryotic cells and is the major target of clinical drugs for managing fungal pathogens, but some of the CYP51 key features important for rational drug design have remained obscure. We report the catalytic properties, ligand-binding profiles, and inhibition of enzymatic activity of C. albicans CYP51 by clinical antifungal drugs that are used systemically (fluconazole, voriconazole, ketoconazole, itraconazole, and posaconazole) and topically (miconazole and clotrimazole) and by a tetrazole-based drug candidate, VT-1161 (oteseconazole: ( R )-2-(2,4-difluorophenyl)-1,1-difluoro-3-(1 H -tetrazol-1-yl)-1-(5-(4-(2,2,2-trifluoroethoxy)phenyl)pyridin-2-yl)propan-2-ol). Among the compounds tested, the first-line drug fluconazole was the weakest inhibitor, whereas posaconazole and VT-1161 were the strongest CYP51 inhibitors. We determined the X-ray structures of C. albicans CYP51 complexes with posaconazole and VT-1161, providing a molecular mechanism for the potencies of these drugs, including the activity of VT-1161 against Candida krusei and Candida glabrata , pathogens that are intrinsically resistant to fluconazole. Our comparative structural analysis outlines phylum-specific CYP51 features that could direct future rational development of more efficient broad-spectrum antifungals. © 2017 by The American Society for Biochemistry and Molecular Biology, Inc.

Heterologous expression of equine CYP3A94 and investigation of a tunable system to regulate co-expressed NADPH P450 oxidoreductase levels.

PubMed

Dettwiler, Ramona; Schmitz, Andrea L; Plattet, Philippe; Zielinski, Jana; Mevissen, Meike

2014-01-01

The activity of cytochrome P450 enzymes depends on the enzyme NADPH P450 oxidoreductase (POR). The aim of this study was to investigate the activity of the equine CYP3A94 using a system that allows to regulate the POR protein levels in mammalian cells. CYP3A94 and the equine POR were heterologously expressed in V79 cells. In the system used, the POR protein regulation is based on a destabilizing domain (DD) that transfers its instability to a fused protein. The resulting fusion protein is therefore degraded by the ubiquitin-proteasome system (UPS). Addition of "Shield-1" prevents the DD fusion protein from degradation. The change of POR levels at different Shield-1 concentrations was demonstrated by cytochrome c reduction, Western immunoblot analysis, and immunocytochemistry. The alteration of CYP3A94 activity was investigated using a substrate (BFC) known to detect CYP3A4 activity. Equine CYP3A94 was demonstrated to be metabolically active and its activity could be significantly elevated by co-expression of POR. Cytochrome c reduction was significantly increased in V79-CYP3A94/DD-POR cells compared to V79-CYP3A94 cells. Surprisingly, incubation with different Shield-1 concentrations resulted in a decrease in POR protein shown by Western immunoblot analysis. Cytochrome c reduction did not change significantly, but the CYP3A94 activity decreased more than 4-fold after incubation with 500 nM and 1 µM Shield-1 for 24 hours. No differences were obtained when V79-CYP3A94 POR cells with and without Shield-1 were compared. The basal activity levels of V79-CYP3A94/DD-POR cells were unexpectedly high, indicating that DD/POR is not degraded without Shield-1. Shield-1 decreased POR protein levels and CYP3A94 activity suggesting that Shield-1 might impair POR activity by an unknown mechanism. Although regulation of POR with the pPTuner system could not be obtained, the cell line V79-CYP3A94/DD-POR system can be used for further experiments to characterize the equine CYP3A94 since the CYP activity was significantly enhanced with co-expressed POR.

Heterologous Expression of Equine CYP3A94 and Investigation of a Tunable System to Regulate Co-Expressed NADPH P450 Oxidoreductase Levels

PubMed Central

Dettwiler, Ramona; Schmitz, Andrea L.; Plattet, Philippe; Zielinski, Jana; Mevissen, Meike

2014-01-01

The activity of cytochrome P450 enzymes depends on the enzyme NADPH P450 oxidoreductase (POR). The aim of this study was to investigate the activity of the equine CYP3A94 using a system that allows to regulate the POR protein levels in mammalian cells. CYP3A94 and the equine POR were heterologously expressed in V79 cells. In the system used, the POR protein regulation is based on a destabilizing domain (DD) that transfers its instability to a fused protein. The resulting fusion protein is therefore degraded by the ubiquitin-proteasome system (UPS). Addition of “Shield-1” prevents the DD fusion protein from degradation. The change of POR levels at different Shield-1 concentrations was demonstrated by cytochrome c reduction, Western immunoblot analysis, and immunocytochemistry. The alteration of CYP3A94 activity was investigated using a substrate (BFC) known to detect CYP3A4 activity. Equine CYP3A94 was demonstrated to be metabolically active and its activity could be significantly elevated by co-expression of POR. Cytochrome c reduction was significantly increased in V79-CYP3A94/DD-POR cells compared to V79-CYP3A94 cells. Surprisingly, incubation with different Shield-1 concentrations resulted in a decrease in POR protein shown by Western immunoblot analysis. Cytochrome c reduction did not change significantly, but the CYP3A94 activity decreased more than 4-fold after incubation with 500 nM and 1 µM Shield-1 for 24 hours. No differences were obtained when V79-CYP3A94 POR cells with and without Shield-1 were compared. The basal activity levels of V79-CYP3A94/DD-POR cells were unexpectedly high, indicating that DD/POR is not degraded without Shield-1. Shield-1 decreased POR protein levels and CYP3A94 activity suggesting that Shield-1 might impair POR activity by an unknown mechanism. Although regulation of POR with the pPTuner system could not be obtained, the cell line V79-CYP3A94/DD-POR system can be used for further experiments to characterize the equine CYP3A94 since the CYP activity was significantly enhanced with co-expressed POR. PMID:25415624

Neurokinin B Exerts Direct Effects on the Ovary to Stimulate Estradiol Production.

PubMed

Qi, Xin; Salem, Mohamed; Zhou, Wenyi; Sato-Shimizu, Miwa; Ye, Gang; Smitz, Johan; Peng, Chun

2016-09-01

Neurokinin B (NKB) and its receptor, NK3R, play critical roles in reproduction by regulating the secretion of the hypothalamic GnRH. NKB and NK3R genes are also expressed in the ovary; however, their physiological roles within the ovary are unknown. The aim of this study was to determine whether NKB acts directly on the ovary to regulate reproduction. Injection of NKB into zebrafish accelerated follicle development, increased the mRNA levels of cyp11a1 and cyp19a1, and enhanced estradiol production. Similarly, NKB induced cyp11a1 and cyp19a1 expression in primary cultures of zebrafish follicular cells and stimulated estradiol production from cultured follicles. Furthermore, NKB activates cAMP response element-binding protein and ERK, and ERK inhibitors abolished the effect of NKB on cyp11a1, whereas protein kinase A and calmodulin-dependent protein kinase II inhibitors that blocked the activation of cAMP response element-binding protein, attenuated the effect of NKB on cyp19a1 expression. In a human granulosa cell line, COV434, a NKB agonist, senktide, also increased CYP11A1 and CYP19A1 mRNA levels and enhanced aromatase protein levels and activities. Small interfering RNA-mediated knockdown of NK3R reduced senktide-induced CYP11A1 and CYP19A1 mRNA levels. Finally, we found that NK3R mRNA was strongly down-regulated in granulosa cells obtained from polycystic ovary syndrome (PCOS) patients when compared with non-PCOS subjects. Taken together, our findings establish a direct action of NKB to induce ovarian estrogen production and raise the possibility that defective signaling of this pathway may contribute to the development of PCOS.

Characterization of the recalcitrant CYP1 phenotype found in Atlantic killifish (Fundulus heteroclitus) inhabiting a Superfund site on the Elizabeth River, VA.

PubMed

Wills, Lauren P; Matson, Cole W; Landon, Chelsea D; Di Giulio, Richard T

2010-08-01

Fundulus heteroclitus (Atlantic killifish) found at the Atlantic Wood Industries Superfund site on the Elizabeth River (ER) in Portsmouth, VA (USA), have been shown to be resistant to the teratogenic effects of creosote-contaminated sediments found at this highly contaminated site. Many of the polycyclic aromatic hydrocarbons (PAHs) found at the ER are known to activate the aryl hydrocarbon receptor (AHR), and are thought to mediate their toxic effects through this pathway. Activation of the AHR results in the induction of several Phase I and II metabolic enzymes. It has been previously shown that the AHR of killifish from the ER are refractory to induction by AHR agonists. To more fully characterize this altered AHR response, we exposed embryos from the ER and from a reference site on King's Creek, VA (KC) to two PAHs, benzo[alpha]pyrene (BaP) and benzo[k]fluoranthene (BkF), and to the dioxin-like compound (DLC), 3,3',4,4',5-pentachlorobiphenyl (PCB126). We compared their developmental and molecular responses by screening the embryos for CYP1A enzyme activity, cardiac deformities, and mRNA expression of CYP1A, CYP1B1, CYP1C1, and AHR2. Basal gene expression of both CYP1A and CYP1B1 was 40% higher in the KC control embryos compared to those from the ER, while AHR2 and CYP1C1 were not significantly different between the populations. Exposure of KC embryos to BaP, BkF, and PCB126 induced CYP1A activity and cardiac deformities. In contrast, CYP1A activity was induced in ER embryos only in response to BkF exposure, although this induction in ER embryos was significantly lower than that observed in KC fish at comparable concentrations. ER embryos did not develop cardiac deformities in response to any of the chemicals tested. CYP1A, CYP1B1 and CYP1C1 mRNA were all significantly induced in the KC embryos after exposure to BaP, BkF and PCB126. Exposure to BaP and BkF in ER embryos resulted in a significant induction of CYP1A mRNA, albeit significantly lower than observed in KC fish. Interestingly, BaP exposure resulted in induction of CYP1B1 at comparable levels in embryos from both populations. CYP1s were not induced in ER embryos in response to PCB126, nor was CYP1C1 for any treatment examined. Additionally, AHR2 was not significantly induced for any of the treatment groups. This study further characterizes the AHR response in killifish, and provides greater insight into the adapted ER phenotype. The ER adaptation involves the suppression of normal AHR-inducible gene expression for all three CYP1 genes, and therefore is likely an alteration in AHR signaling or control. Copyright 2010 Elsevier B.V. All rights reserved.

Enantioselective N-demethylation and hydroxylation of sibutramine in human liver microsomes and recombinant cytochrome p-450 isoforms.

PubMed

Shinde, Dhananjay D; Kim, Min-Jung; Jeong, Eun-Sook; Kim, Yang-Weon; Lee, Ji-Woo; Shin, Jae-Gook; Kim, Dong-Hyun

2014-01-01

The enantioselective metabolism of sibutramine was examined using human liver microsomes (HLM) and recombinant cytochrome P-450 (CYP) isoforms. This drug is metabolized to N-mono-desmethyl- (M1) and N,N-di-desmethylsibutramine (M2), and subsequent hydroxylation results in hydroxyl M1 (HM1) and hydroxyl M2 (HM2). No significant difference was noted in formation of M1from sibutramine between R- and S-sibutramine in HLM. However, S-enantiomers of M1 and M2 were preferentially metabolized to M2, HM1, and HM2compared to R-enantiomers in HLM, and intrinsic clearance (Clint) ratios of S-enantiomers/R-enantiomers were 1.97, 4.83, and 9.94 for M2, HM1, and HM2, respectively. CYP3A4 and CYP3A5 were only involved in the formation of M1, whereas CYP2B6 and CYP2C19 were responsible for all metabolic reactions of sibutramine. CYP2C19 and CYP3A5 displayed catalytic preference for S-sibutramine to S-M1, whereas CYP2B6 and CYP3A4 showed little or no stereoselectivity in metabolism of sibutramine to M1. In the case of M2 formation, CYP2B6 metabolized S-M1 more rapidly than R-M1 with a Clint ratio of 2.14. However, CYP2C19 catalyzed less S-M1 than R-M1 and the Clint ratio of S-M1 to R-M1 was 0.65. The most significant enantioselectivity was observed in formation of HM1 from M1, and HM2 from M2. CYP2B6 and CYP2C19 exhibited preferential catalysis of formation of hydroxyl metabolites from S-enantiomers rather than R-enantiomers. These results indicate that S-sibutramine was more rapidly metabolized by CYP isoforms than R-sibutramine, and that enantioselective metabolism needs to be considered in drug interactions involving sibutramine and co-administered drugs.

Human Placental Lactogen Induces CYP2E1 Expression via PI 3-Kinase Pathway in Female Human Hepatocytes

PubMed Central

Lee, Jin Kyung; Chung, Hye Jin; Fischer, Liam; Fischer, James; Gonzalez, Frank J.

2014-01-01

The state of pregnancy is known to alter hepatic drug metabolism. Hormones that rise during pregnancy are potentially responsible for the changes. Here we report the effects of prolactin (PRL), placental lactogen (PL), and growth hormone variant (GH-v) on expression of major hepatic cytochromes P450 expression and a potential molecular mechanism underlying CYP2E1 induction by PL. In female human hepatocytes, PRL and GH-v showed either no effect or small and variable effects on mRNA expression of CYP1A2, 2A6, 2B6, 2C9, 2C19, 2D6, 2E1, 3A4, and 3A5. On the other hand, PL increased expression level of CYP2E1 mRNA with corresponding increases in CYP2E1 protein and activity levels. Results from hepatocytes and HepaRG cells indicate that PL does not affect the expression or activity of HNF1α, the known transcriptional activator of basal CYP2E1 expression. Furthermore, transient transfection studies and Western blot results showed that STAT signaling, the previously known mediator of PL actions in certain tissues, does not play a role in CYP2E1 induction by PL. A chemical inhibitor of PI3-kinase signaling significantly repressed the CYP2E1 induction by PL in human hepatocytes, suggesting involvement of PI3-kinase pathway in CYP2E1 regulation by PL. CYP2E1-humanized mice did not exhibit enhanced CYP2E1 expression during pregnancy, potentially because of interspecies differences in PL physiology. Taken together, these results indicate that PL induces CYP2E1 expression via PI3-kinase pathway in human hepatocytes. PMID:24408518

Cytochrome P450 CYP3A in marsupials: cloning and identification of the first CYP3A subfamily member, isoform 3A70 from Eastern gray kangaroo (Macropus giganteus).

PubMed

El-Merhibi, Adaweyah; Ngo, Suong N T; Marchant, Ceilidh L; Height, Tamara A; Stupans, Ieva; McKinnon, Ross A

2012-09-15

Australian marsupials are unique fauna that have evolved and adapted to unique environments and thus it is likely that their detoxification systems differ considerably from those of well-studied eutherian mammals. Knowledge of these processes in marsupials is therefore vital to understanding the consequences of exposure to xenobiotics. Cytochromes P450 (CYPs) are critically important in the oxidative metabolism of a diverse array of both xenobiotics and endogenous substrates. In this study we have cloned and characterized CYP3A70, the first identified member of the CYP3A gene subfamily from Eastern gray kangaroo (Macropus giganteus). A 1665 base pair kangaroo hepatic CYP3A complete cDNA, designated CYP3A70, was cloned by reverse transcription-polymerase chain reaction approaches, which encodes a protein of 506 amino acids. The CYP3A70 cDNA shares approximately 71% nucleotide and 65% amino acid sequence homology to human CYP3A4 and displays high sequence similarity to other published mammalian CYP3As from human, monkey, cow, pig, dog, rat, rabbit, mouse, hamster, and guinea pig. Transfection of the CYP3A70 cDNAs into 293T cells resulted in stable cell lines expressing a CYP3A immuno-reactive protein that was recognized by a goat anti-human CYP3A4 polyclonal antibody. The anti-human CYP3A4 antibody also detected immunoreactive proteins in liver microsomes from all test marsupials, including the kangaroo, koala, wallaby, and wombat, with multiple CYP3A immunoreactive bands observed in kangaroo and wallaby tissues. Relatively, very low CYP catalytic activity was detected for the kangaroo CYP3A70 cDNA-expressed proteins (19.6 relative luminescent units/μg protein), which may be due to low protein expression levels. Collectively, this study provides primary molecular data regarding the Eastern kangaroo hepatic CYP3A70 gene and enables further functional analyses of CYP3A enzymes in marsupials. Copyright © 2012 Elsevier B.V. All rights reserved.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Muhsain, Siti Nur Fadzilah, E-mail: sitinurfadzilah077@ppinang.uitm.edu.my; Faculty of Pharmacy, University Teknologi Mara; Lang, Matti A., E-mail: m.lang@uq.edu.au

The intracellular level of bilirubin (BR), an endogenous antioxidant that is cytotoxic at high concentrations, is tightly controlled within the optimal therapeutic range. We have recently described a concerted intracellular BR regulation by two microsomal enzymes: heme oxygenase 1 (HMOX1), essential for BR production and cytochrome P450 2A5 (CYP2A5), a BR oxidase. Herein, we describe targeting of these enzymes to hepatic mitochondria during oxidative stress. The kinetics of microsomal and mitochondrial BR oxidation were compared. Treatment of DBA/2J mice with 200 mg pyrazole/kg/day for 3 days increased hepatic intracellular protein carbonyl content and induced nucleo-translocation of Nrf2. HMOX1 and CYP2A5more » proteins and activities were elevated in microsomes and mitoplasts but not the UGT1A1, a catalyst of BR glucuronidation. A CYP2A5 antibody inhibited 75% of microsomal BR oxidation. The inhibition was absent in control mitoplasts but elevated to 50% after treatment. An adrenodoxin reductase antibody did not inhibit microsomal BR oxidation but inhibited 50% of mitochondrial BR oxidation. Ascorbic acid inhibited 5% and 22% of the reaction in control and treated microsomes, respectively. In control mitoplasts the inhibition was 100%, which was reduced to 50% after treatment. Bilirubin affinity to mitochondrial and microsomal CYP2A5 enzyme is equally high. Lastly, the treatment neither released cytochrome c into cytoplasm nor dissipated membrane potential, indicating the absence of mitochondrial membrane damage. Collectively, the observations suggest that BR regulatory enzymes are recruited to mitochondria during oxidative stress and BR oxidation by mitochondrial CYP2A5 is supported by mitochondrial mono-oxygenase system. The induced recruitment potentially confers membrane protection. - Highlights: • Pyrazole induces oxidative stress in the mouse liver. • Pyrazole-induced oxidative stress induces mitochondrial targeting of key bilirubin regulatory enzymes, HMOX1, BVR and CYP2A5. • Mitochondrial cytochrome P450 2A5 (CYP2A5) can function as bilirubin oxidase. • Mitochondrial targeting of the key microsomal enzymes is not associated with mitochondrial membrane disruption.« less

New potent and selective cytochrome P450 2B6 (CYP2B6) inhibitors based on three-dimensional quantitative structure-activity relationship (3D-QSAR) analysis

PubMed Central

Korhonen, L E; Turpeinen, M; Rahnasto, M; Wittekindt, C; Poso, A; Pelkonen, O; Raunio, H; Juvonen, R O

2007-01-01

Background and purpose: The cytochrome P450 2B6 (CYP2B6) enzyme metabolises a number of clinically important drugs. Drug-drug interactions resulting from inhibition or induction of CYP2B6 activity may cause serious adverse effects. The aims of this study were to construct a three-dimensional structure-activity relationship (3D-QSAR) model of the CYP2B6 protein and to identify novel potent and selective inhibitors of CYP2B6 for in vitro research purposes. Experimental approach: The inhibition potencies (IC50 values) of structurally diverse chemicals were determined with recombinant human CYP2B6 enzyme. Two successive models were constructed using Comparative Molecular Field Analysis (CoMFA). Key results: Three compounds proved to be very potent and selective competitive inhibitors of CYP2B6 in vitro (IC50<1 μM): 4-(4-chlorobenzyl)pyridine (CBP), 4-(4-nitrobenzyl)pyridine (NBP), and 4-benzylpyridine (BP). A complete inhibition of CYP2B6 activity was achieved with 0.1 μM CBP, whereas other CYP-related activities were not affected. Forty-one compounds were selected for further testing and construction of the final CoMFA model. The created CoMFA model was of high quality and predicted accurately the inhibition potency of a test set (n=7) of structurally diverse compounds. Conclusions and implications: Two CoMFA models were created which revealed the key molecular characteristics of inhibitors of the CYP2B6 enzyme. The final model accurately predicted the inhibitory potencies of several structurally unrelated compounds. CBP, BP and NBP were identified as novel potent and selective inhibitors of CYP2B6 and CBP especially is a suitable inhibitor for in vitro screening studies. PMID:17325652

Characterization of the cytochrome P450 enzymes and enzyme kinetic parameters for metabolism of BVT.2938 using different in vitro systems.

PubMed

Baranczewski, Pawel; Edlund, Per Olof; Postlind, Hans

2006-03-18

An important step in the drug development process is identification of enzymes responsible for metabolism of drug candidates and determination of enzyme kinetic parameters. These data are used to increase understanding of the pharmacokinetics and possible metabolic-based drug interactions of drug candidates. The aim of the present study was to characterize the cytochrome P450 enzymes and enzyme kinetic parameters for metabolism of BVT.2938 [1-(3-{2-[(2-ethoxy-3-pyridinyl)oxy]ethoxy}-2-pyrazinyl)-2(R)-methylpiperazine], a potent and selective 5HT2c-receptor agonist. The enzyme kinetic parameters were determined for formation of three main metabolites of BVT.2938 using human liver microsomes and expressed cytochrome P450 (CYP) isoforms. The major metabolite was formed by hydroxylation of the pyridine ring (CL(int)=27 microl/mgmin), and was catalysed by both CYP2D6*1 and CYP1A1, with K(m) values corresponding to 1.4 and 2.7 microM, respectively. The results from enzyme kinetic studies were confirmed by incubation of BVT.2938 in the presence of the chemical inhibitor of CYP2D6*1, quinidine. Quinidine inhibited the formation of the major metabolite by approximately 90%. Additionally, studies with recombinant expressed CYP isoforms from rat indicated that formation of the major metabolite of BVT.2938 was catalysed by CYP2D2. This result was further confirmed by experiments with liver slices from different rat strains, where the formation of the metabolite correlated with phenotype of CYP2D2 isoform (Sprague-Dawley male, extensive; Dark Agouti male, intermediate; Dark Agouti female, poor metabolizer). The present study showed that the major metabolite of BVT.2938 is formed by hydroxylation of the pyridine ring and catalysed by CYP2D6*1. CYP1A1 is also involved in this reaction and its role in extra-hepatic metabolism of BVT.2938 might be significant.

Effect of the cytochrome P450 2C19 inhibitor omeprazole on the pharmacokinetics and safety profile of bortezomib in patients with advanced solid tumours, non-Hodgkin's lymphoma or multiple myeloma.

PubMed

Quinn, David I; Nemunaitis, John; Fuloria, Jyotsna; Britten, Carolyn D; Gabrail, Nashat; Yee, Lorrin; Acharya, Milin; Chan, Kai; Cohen, Nadine; Dudov, Assen

2009-01-01

Bortezomib, an antineoplastic for the treatment of relapsed multiple myeloma and mantle cell lymphoma, undergoes metabolism through oxidative deboronation by cytochrome P450 (CYP) enzymes, primarily CYP3A4 and CYP2C19. Omeprazole, a proton-pump inhibitor, is primarily metabolized by and demonstrates high affinity for CYP2C19. This study investigated whether coadministration of omeprazole affected the pharmacokinetics, pharmacodynamics and safety profile of bortezomib in patients with advanced cancer. The variability of bortezomib pharmacokinetics with CYP enzyme polymorphism was also investigated. This open-label, crossover, pharmacokinetic drug-drug interaction study was conducted at seven institutions in the US and Europe between January 2005 and August 2006. Patients who had advanced solid tumours, non-Hodgkin's lymphoma or multiple myeloma, were aged >/=18 years, weighed >/=50 kg and had a life expectancy of >/=3 months were eligible. Patients received bortezomib 1.3 mg/m2 on days 1, 4, 8 and 11 for two 21-day cycles, plus omeprazole 40 mg in the morning of days 6-10 and in the evening of day 8 in either cycle 1 (sequence 1) or cycle 2 (sequence 2). On day 21 of cycle 2, patients benefiting from therapy could continue to receive bortezomib for six additional cycles. Blood samples for pharmacokinetic/pharmacodynamic evaluation were collected prior to and at various timepoints after bortezomib administration on day 8 of cycles 1 and 2. Blood samples for pharmacogenomics were also collected. Pharmacokinetic parameters were calculated by noncompartmental analysis of plasma concentration-time data for bortezomib administration on day 8 of cycles 1 and 2, using WinNonlin version 4.0.1.a software. The pharmacodynamic profile was assessed using a whole-blood 20S proteasome inhibition assay. Twenty-seven patients (median age 64 years) were enrolled, 12 in sequence 1 and 15 in sequence 2, including eight and nine pharmacokinetic-evaluable patients, respectively. Bortezomib pharmacokinetic parameters were similar when bortezomib was administered alone or with omeprazole (maximum plasma concentration 120 vs 123 ng/mL; area under the plasma concentration-time curve from 0 to 72 hours 129 vs 135 ng . h/mL). The pharmacodynamic parameters were also similar (maximum effect 85.8% vs 93.7%; area under the percent inhibition-time curve over 72 hours 4052 vs 3910 % x h); the differences were not statistically significant. Pharmacogenomic analysis revealed no meaningful relationships between CYP enzyme polymorphisms and pharmacokinetic/pharmacodynamic parameters. Toxicities were generally similar between patients in sequence 1 and sequence 2, and between cycle 1 and cycle 2 in both treatment sequences. Among 26 evaluable patients, 13 (50%) were assessed as benefiting from bortezomib at the end of cycle 2 and continued to receive treatment. No impact on the pharmacokinetics, pharmacodynamics and safety profile of bortezomib was seen with coadministration of omeprazole. Concomitant administration of bortezomib and omeprazole is unlikely to cause clinically significant drug-drug interactions and is unlikely to have an impact on the efficacy or safety of bortezomib.

DOE Office of Scientific and Technical Information (OSTI.GOV)

Bell, Stephen G.; Hoskins, Nicola; Xu Feng

Four (CYP195A2, CYP199A2, CYP203A1, and CYP153A5) of the seven P450 enzymes, and palustrisredoxin A, a ferredoxin associated with CYP199A2, from the metabolically diverse bacterium Rhodopseudomonas palustris have been expressed and purified. A range of substituted benzenes, phenols, benzaldehydes, and benzoic acids was shown to bind to the four P450 enzymes. Monooxygenase activity of CYP199A2 was reconstituted with palustrisredoxin A and putidaredoxin reductase of the P450cam system from Pseudomonas putida. We found that 4-ethylbenzoate and 4-methoxybenzoate were oxidized to single products, and 4-methoxybenzoate was demethylated to form 4-hydroxybenzoate. Crystals of substrate-free CYP199A2 which diffracted to {approx}2.0 A have been obtained.

Liver Cytochrome P450 3A Ubiquitination in Vivo by gp78/Autocrine Motility Factor Receptor and C Terminus of Hsp70-interacting Protein (CHIP) E3 Ubiquitin Ligases

PubMed Central

Kim, Sung-Mi; Acharya, Poulomi; Engel, Juan C.; Correia, Maria Almira

2010-01-01

CYP3A4 is a dominant human liver cytochrome P450 enzyme engaged in the metabolism and disposition of >50% of clinically relevant drugs and held responsible for many adverse drug-drug interactions. CYP3A4 and its mammalian liver CYP3A orthologs are endoplasmic reticulum (ER)-anchored monotopic proteins that undergo ubiquitin (Ub)-dependent proteasomal degradation (UPD) in an ER-associated degradation (ERAD) process. These integral ER proteins are ubiquitinated in vivo, and in vitro studies have identified the ER-integral gp78 and the cytosolic co-chaperone, CHIP (C terminus of Hsp70-interacting protein), as the relevant E3 Ub-ligases, along with their cognate E2 Ub-conjugating enzymes UBC7 and UbcH5a, respectively. Using lentiviral shRNA templates targeted against each of these Ub-ligases, we now document that both E3s are indeed physiologically involved in CYP3A ERAD/UPD in cultured rat hepatocytes. Accordingly, specific RNAi resulted in ≈80% knockdown of each hepatic Ub-ligase, with a corresponding ≈2.5-fold CYP3A stabilization. Surprisingly, however, such stabilization resulted in increased levels of functionally active CYP3A, thereby challenging the previous notion that E3 recognition and subsequent ERAD of CYP3A proteins required ab initio their structural and/or functional inactivation. Furthermore, coexpression in HepG2 cells of both CYP3A4 and gp78, but not its functionally inactive RING-finger mutant, resulted in enhanced CYP3A4 loss greater than that in corresponding cells expressing only CYP3A4. Stabilization of a functionally active CYP3A after RNAi knockdown of either of the E3s, coupled with the increased CYP3A4 loss on gp78 or CHIP coexpression, suggests that ERAD-associated E3 Ub-ligases can influence clinically relevant drug metabolism by effectively regulating the physiological CYP3A content and consequently its function. PMID:20819951

Reproductive toxicity of azoxystrobin to adult zebrafish (Danio rerio).

PubMed

Cao, Fangjie; Zhu, Lizhen; Li, Hui; Yu, Song; Wang, Chengju; Qiu, Lihong

2016-12-01

In the past few decades, extensive application of azoxystrobin has led to great concern regarding its adverse effects on aquatic organisms. The objective of the present study was to evaluate the reproductive toxicity of azoxystrobin to zebrafish. After adult zebrafish of both sexes were exposed to 2, 20 and 200 μg/L azoxystrobin for 21 days, egg production, the fertilization rate, the gonadosomatic index (GSI) and hepatosomatic index (HSI), 17β-estradiol (E2), testosterone (T) and vitellogenin (Vtg) concentrations, and histological alterations in the gonads and livers were measured. Meanwhile, expression alterations of genes encoding gonadotropins and gonadotropin receptors (fshb, lhb, fshr and lhr), steroid hormone receptors (era, er2b and ar), steroidogenic enzymes (cyp11a, cyp11b, cyp17, cyp19a, cyp19b, hsd3b and hsd17b) in the hypothalamic-pituitary-gonad (HPG) axis and vitellogenin (vtg1 and vtg2) in the livers were also investigated. The results showed that reduced egg production and fertilization rates were observed at 200 μg/L azoxystrobin. In female zebrafish, reduced E2 and Vtg concentrations, decreased GSI, increased T concentrations, and histological alterations in the ovaries and livers were observed at 200 μg/L azoxystrobin, along with significant down-regulation of lhb, cyp19b, lhr, cyp19a, vtg1 and vtg2, and up-regulation of cyp17, hsd3b and hsd17b. In male zebrafish, increased E2 and Vtg concentrations, reduced T concentration and GSI, and histological alterations in the testes and livers were observed after exposure to 20 and 200 μg/L azoxystrobin, along with significant up-regulations of cyp19b, cyp11a, cyp17, cyp19a, hsd3b and hsd17b, vtg1 and vtg2. Moreover, cyp11a, hsd3b, cyp19a, vtg1 and vtg2 in male zebrafish were significantly up-regulated after treatment with 2 μg/L azoxystrobin. The results of the present study indicate that azoxystrobin led to reproductive toxicity in zebrafish and male zebrafish were more sensitive to azoxystrobin than female zebrafish. Copyright © 2016 Elsevier Ltd. All rights reserved.

Determination of the human cytochrome P450 monooxygenase catalyzing the enantioselective oxidation of 2,2',3,5',6-pentachlorobiphenyl (PCB 95) and 2,2',3,4,4',5',6-heptachlorobiphenyl (PCB 183).

PubMed

Nagayoshi, Haruna; Kakimoto, Kensaku; Konishi, Yoshimasa; Kajimura, Keiji; Nakano, Takeshi

2017-10-17

2,2',3,5',6-Pentachlorobiphenyl (PCB 95) and 2,2',3,4,4',5',6-heptachlorobiphenyl (PCB 183) possess axial chirality and form the aS and aR enantiomers. The enantiomers of these congeners have been reported to accumulate in the human body enantioselectively via unknown mechanisms. In this study, we determined the cytochrome P450 (CYP) monooxygenase responsible for the enantioselective oxidization of PCB 95 and PCB 183, using a recombinant human CYP monooxygenase. We evaluated 13 CYP monooxygenases, namely CYP1A1, CYP1A2, CYP1B1, CYP2A6, CYP2B6, CYP2C8, CYP2C19, CYP2E1, CYP2J2, CYP3A4, CYP3A5, CYP4F2, and aromatase (CYP19), and revealed that CYP2A6 preferably oxidizes aS-PCB 95 enantioselectively; however, it did not oxidize PCB 183. The enantiomer composition was elevated from 0.5 (racemate) to 0.54. In addition, following incubation with CYP2A6, the enantiomer fraction (EF) of PCB 95 demonstrated a time-dependent increase.

Enzymes oxidizing the azo dye 1-phenylazo-2-naphthol (Sudan I) and their contribution to its genotoxicity and carcinogenicity.

PubMed

Stiborova, Marie; Schmeiser, Heinz H; Frei, Eva; Hodek, Petr; Martinek, Vaclav

2014-01-01

Sudan I [1-(phenylazo)-2-naphthol, C.I. Solvent Yellow 14] is an industrial dye, which was found as a contaminant in numerous foods in several European countries. Because Sudan I has been assigned by the IARC as a Category 3 carcinogen, the European Union decreed that it cannot be utilized as food colorant in any European country. Sudan I induces the malignancies in liver and urinary bladder of rats and mice. This carcinogen has also been found to be a potent mutagen, contact allergen and sensitizer, and exhibits clastogenic properties. The oxidation of Sudan I increases its toxic effects and leads to covalent adducts in DNA. Identification of enzymatic systems that contribute to Sudan I oxidative metabolism to reactive intermediates generating such covalent DNA adducts on the one hand, and to the detoxification of this carcinogen on the other, is necessary to evaluate susceptibility to this toxicant. This review summarizes the identification of such enzymes and the molecular mechanisms of oxidation reactions elucidated to date. Human and animal cytochrome P450 (CYP) and peroxidases are capable of oxidizing Sudan I. Of the CYP enzymes, CYP1A1 is most important both in Sudan I detoxification and its bio-activation. Ring-hydroxylated metabolites and a dimer of this carcinogen were found as detoxification products of Sudan I generated with CYPs and peroxidases, respectively. Oxidative bio-activation of this azo dye catalyzed by CYPs and peroxidases leads to generation of proximate genotoxic metabolites (the CYP-catalyzed formation of the benzenediazonium cation and the peroxidase-mediated generation of one-electron oxidation products), which covalently modify DNA both in vitro and in vivo. The predominant DNA adduct generated with the benzenediazonium cation was characterized to be 8-(phenylazo)guanine. The Sudan I radical species mediated by peroxidases reacts with the -NH2 group in (deoxy)guanosine, generating the 4-[(deoxy)guanosin-N(2)-yl]Sudan I product. Sudan I was also found to be a strong inducer of CYP1A1 and its enzyme activity mediated by the aryl hydrocarbon receptor, thereby increasing its own genotoxic potential and the cancer risk for humans.

Effects of sex, weight, diet and hCG administration on levels of skatole and indole in the liver and hepatic activities of cytochromes P4502E1 and P4502A6 in pigs.

PubMed

Zamaratskaia, G; Chen, G; Lundström, K

2006-02-01

Cytochromes P4502E1 (CYP2E1) and P4502A6 (CYP2A6) catalyse metabolic reactions of skatole and indole metabolism. The objectives of this study were as follows: to evaluate whether activities of CYP2E1 and CYP2A6 in pigs of two live weights (LW) differ between males and females; to investigate whether activities of CYP2E1 and CYP2A6 are affected by hCG stimulation; and to investigate whether the levels of skatole and indole in the liver and the activities of CYP2E1 and CYP2A6 are affected by raw potato starch (RPS). Female pigs expressed higher CYP2A6 activity at 90kg LW, and higher CYP2E1 activity at 115kg LW compared to male pigs. Skatole levels in the liver were higher in male pigs than in female pigs at both LW, whereas indole levels were higher in males only at 115 kg LW. Neither levels of indolic compounds in the liver nor enzyme activities were affected by hCG stimulation. The inclusion of RPS in the diet reduced skatole levels in the liver in both sexes and increased CYP2A6 activity in female pigs. It was concluded that the incidence of boar taint may depend on both skatole amount, which reach the liver, and the activities of enzymes involved in skatole metabolism, which may vary depending on sex, live weight, and diet.