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1

A High-Performance Liquid Chromatographic–Tandem Mass Spectrometric Method for the Determination of Ethyl Glucuronide and Ethyl Sulfate in Urine Validated According to Forensic Guidelines  

PubMed Central

Ethyl glucuronide (EtG) and ethyl sulfate (EtS) are powerful markers for alcohol intake and abuse. Several analytical procedures for the quantification of EtG and EtG in serum and urine have been developed so far. Many of the published methods show limits of detections (LODs) or limits of quantifications (LOQs) for EtG in urine within the range of 0.1 mg/L or higher. Since this is the actual cutoff value for proving abstinence in Germany, problems may occur if urine samples are highly diluted. In this paper, the validation of a highly sensitive, fast and simple LC–MS–MS for the determination of EtG and EtS in urine is described. The calibration curves for EtG and EtS is linear over the whole range (0.025–2.0 mg/L). Very low detection limits can be achieved (LOD: EtG 0.005 mg/L, EtS 0.005 mg/L; and LOQ: EtG 0.019 mg/L, EtS 0.015 mg/L). All data for selectivity, precision and accuracy, recovery, as well as for the processed sample and the freeze/thaw stability, comply with the guidelines of the German Society of Toxicological and Forensic Chemistry. Strong matrix-related effects can be compensated for by using an internal standard. Finally, the applicability of the procedure is proven by analysis of 87 human urine samples and by successful participation in interlaboratory comparison tests. PMID:22291056

Albermann, M.E.; Musshoff, F.; Madea, B.

2012-01-01

2

Gas chromatographic determination of ethyl glucuronide in hair: Comparison between tandem mass spectrometry and single quadrupole mass spectrometry.  

PubMed

Ethyl glucuronide (EtG), a minor metabolite of ethanol, accumulates in hair and is currently used as a long-term marker for the detection of chronic and excessive alcohol consumption. Sensitive methods are required to differentiate teetotalers from moderate drinkers according to the established cut-off (i.e., 7pg/mg hair). The aim of this study was to develop a sensitive method using gas chromatography coupled to tandem mass spectrometry (GC-MS/MS) operated in the negative ion chemical ionization (NICI) mode. The validated method was applied to hair samples from teetotalers, moderate and excessive alcohol consumers, and results were compared to a previously validated GC-NICI-MS method. The developed GC-NICI-MS/MS method showed linearity over a range from 2 to 400pg/mg hair, with a limit of detection (LOD) of 0.05pg/mg hair and a lower limit of quantification (LLOQ) of 0.2pg/mg hair, compared to an LOD of 0.5pg/mg hair and LLOQ of 1.5pg/mg hair obtained with GC-NICI-MS. Furthermore, lower background noise was observed using GC-NICI-MS/MS. Comparison of results of hair samples (n=58) obtained by GC-NICI-MS and GC-NICI-MS/MS showed no significant difference between both methods (paired-sample t-test, p>0.05; mean CV=1.0%). The differences between both methods were larger for EtG concentrations<30mg/pg hair (mean CV=1.7%) than for EtG concentrations>30mg/pg hair (mean CV=0.7%). This suggests a higher selectivity of GC-NICI-MS/MS at lower concentrations. In conclusion, by using GC-NICI-MS/MS, a higher analytical selectivity and an improved signal to noise ratio, can be achieved. Although GC-NICI-MS would not change the interpretation of the EtG concentrations, the present GC-NICI-MS/MS method should preferentially be used for the determination of EtG in hair, especially when differentiating between teetotalers and moderate drinkers according to the current cut-off (i.e., 7pg/mg hair). PMID:25562794

Cappelle, Delphine; Neels, Hugo; Yegles, Michel; Paulus, Jeff; van Nuijs, Alexander L N; Covaci, Adrian; Crunelle, Cleo L

2015-04-01

3

Comparison of ethyl glucuronide (EtG) and fatty acid ethyl esters (FAEEs) concentrations in hair for testing abstinence  

Microsoft Academic Search

Hair analysis is a powerful tool for retrospective drug analysis. By determining the minor ethanol metabolites ethyl glucuronide\\u000a (EtG) and fatty acid ethyl esters (FAEEs) in hair, even a previous consumption of alcohol is detectable. However, previous\\u000a studies showed a lack of correlation if both parameters are determined simultaneously. A further study was conducted to confirm\\u000a or refute these results.

M. E. Albermann; F. Musshoff; B. Madea

2011-01-01

4

Validation of a headspace solid-phase microextraction-GC-MS/MS for the determination of ethyl glucuronide in hair according to forensic guidelines.  

PubMed

The analysis of ethyl glucuronide (EtG) in hair is a powerful tool for chronic alcohol abuse control because of the typical wide detection window of the hair matrix and due to the possibility of segmentation, allowing evaluation of alcohol consumption in different periods. Additionally, EtG in hair is often the only diagnostic parameter of choice for alcohol abuse when other clinical parameters such as ALT, AST, gammaGT and CDT (asialotransferrin and disialotransferrin) are in the normal range and EtG in urine negative. In this paper, we describe the development, optimization and validation of a new method based on hair extraction with water, clean-up by solid phase extraction (SPE), derivatization with heptafluorobutyric anhydride and headspace solid-phase microextraction (HS-SPME) in combination with GC-MS/MS according to forensic guidelines. The assay linearity of EtG was confirmed over the range from 2.8 to 1000 pg/mg hair, with a coefficient of determination (r(2)) above 0.999. The LLOQ was 2.8 pg/mg and the LLOD was 0.6 pg/mg. An error profile calculated according to the "Guide to the Expression of Uncertainty in Measurement" (GUM) at 99% confidence intervals for the range 5-750 pg/mg hair did not exceed 10%. This range corresponds to more than 98% of the positive samples analysed. PMID:20061100

Agius, Ronald; Nadulski, Thomas; Kahl, Hans-Gerhard; Schräder, Johannes; Dufaux, Bertin; Yegles, Michel; Pragst, Fritz

2010-03-20

5

SENSITIVITY AND SPECIFICITY OF URINARY ETHYL GLUCURONIDE AND ETHYL SULFATE IN LIVER DISEASE PATIENTS  

PubMed Central

Background It is important to monitor alcohol use in the care of liver disease patients, but patient self-report can be unreliable. We therefore evaluated the performance of urine ethyl glucuronide (EtG) and ethyl sulfate (EtS) in detecting alcohol use in the days preceding a clinical encounter. Methods Subjects (n=120) were recruited at a university-based Hepatology clinic or during hospitalization. Alcohol consumption was ascertained by validated self-report measures. Urine EtG (cutoff 100 ng/mL) and EtS (cutoff 25 ng/mL) concentrations were assayed by a contracted laboratory using tandem mass spectrometry. The sensitivity and specificity of each biomarker in the detection of drinking during the 3 and 7 days preceding the clinic visit were determined, as well as the influence of liver disease severity on these results. Results Urine EtG (sensitivity 76%, specificity 93%) and urine EtS (sensitivity 82%, specificity 86%) performed well in identifying recent drinking, and liver disease severity does not affect biomarker performance. After elimination of one false negative self-report, urine EtG > 100 ng/mL was 100% specific for drinking within the past week, whereas 9% of the subjects without evidence of alcohol drinking for at least one week had EtS > 25 ng/mL. Conclusions Urine EtG and EtS can objectively supplement the detection of recent alcohol use in patients with liver disease. Additional research may determine optimal methods for integrating these tests into clinical care. PMID:22725265

Stewart, Scott H.; Koch, David G.; Burgess, Douglas M.; Willner, Ira R.; Reuben, Adrian

2012-01-01

6

Assessment of UDP-glucuronosyltransferase catalyzed formation of ethyl glucuronide in human liver microsomes and recombinant UGTs  

Microsoft Academic Search

While ethanol is primarily metabolized to acetaldehyde and acetic acid via alcohol dehydrogenase, a minor but increasingly important pathway in the field of forensic science involves the conjugation of glucuronic acid to form an ethyl glucuronide (EtG) metabolite. The kinetics of ethyl glucuronide formation were examined in human liver microsomes (HLM) and recombinant UDP-glucuronosyltransferases (UGTs). The metabolite exhibited a relatively

Robert S. Foti; Michael B. Fisher

2005-01-01

7

Ethyl glucuronide and ethyl sulfate in autopsy samples 27 years after death.  

PubMed

The unique case of a 50-year-old known alcoholic whose corpse was exhumed 27 years after death is reported. The man apparently committed suicide by hanging, but many years later the case was questioned and homicide-linked to a long-lasting serial killer case-was suspected. Thus, the corpse was exhumed, and at the autopsy it was found to be naturally mummified. This fact permitted the analysis of body tissues with the aim to investigate the persistence of ethanol conjugates in the biological material 27 years after death. Fragments of liver and kidney, a blood clot, and a hair strand were collected and submitted to liquid chromatography tandem mass spectrometry analysis. Ethyl glucuronide (EtG) and ethyl sulfate (EtS) were identified and quantified in the liver, the kidney, and the blood clot. Hair analysis was found to be severely affected by ion suppression even after solid phase extraction. Consequently, EtG was identified in all hair segments (0-3 cm, 3-6 cm, and 6-10 cm), but no reliable quantification could be carried out. In summary, our findings demonstrate that, notwithstanding the expected conjugate degradation, EtG and EtS can be indicative of ante-mortem use of alcohol even many years after death. PMID:18661140

Politi, Lucia; Morini, Luca; Mari, Francesco; Groppi, Angelo; Bertol, Elisabetta

2008-11-01

8

Testing for ethanol markers in hair: discrepancies after simultaneous quantification of ethyl glucuronide and fatty acid ethyl esters.  

PubMed

The hair of 97 cases were analysed for ethyl glucuronide (EtG) and fatty acid ethyl esters (FAEE, including ethyl myristate, ethyl palmitate, ethyl oleate and ethyl stearate) according to the Society of Hair Testing guidelines to examine the role of both tests in documenting chronic excessive alcohol drinking, particularly when the results are in contradiction. 27 (27.8%) results were EtG negative and FAEE positive, when applying the SoHT cut-offs, probably due to the use of alcohol-containing hair products. Four cases (4.1%) were EtG positive and FAEE negative that were attributed to the use of herbal lotions containing EtG. PMID:24794020

Kintz, P; Nicholson, D

2014-10-01

9

Voucher-Based Reinforcement for Alcohol Abstinence Using the Ethyl-Glucuronide Alcohol Biomarker  

ERIC Educational Resources Information Center

This study assessed the effects of a contingency management (CM) intervention for alcohol consumption in 10 alcohol-dependent participants. An ABCA design was used. Vouchers were provided contingent on results of ethyl glucuronide (EtG) urine tests (an alcohol biomarker with a 2-day detection period) and alcohol breath tests during the C phase.…

McDonell, Michael G.; Howell, Donelle N,; McPherson, Sterling; Cameron, Jennifer M.; Srebnik, Debra; Roll, John M.; Ries, Richard K.

2012-01-01

10

Ethyl glucuronide findings in hair samples from the mummies of the Capuchin Catacombs of Palermo.  

PubMed

The Capuchin Catacombs of Palermo contain over 1800 preserved bodies: friars, priests and laypeople including men, women, and children. The bodies were accessible to family members who could visit the deceased and commemorate them through prayers. The "Sicily Mummy Project" analyzed hair samples from 38 mummies to determine the presence of ethyl glucuronide (EtG) using a routine procedure in our accredited laboratory of liquid chromatography coupled with mass spectrometry. The limit of quantification was 2.3 pg/mg. The hair samples were from 1.5 to 12 cm in length. All samples were analyzed in 2 segments (seg. A 0-3 cm and seg. B the remainder). Samples <4 cm in length were cut in half. In 31 out of 76 segments positive results were obtained for EtG, with concentrations between 2.5 and 531.3 pg/mg (mean 73.8, median 13.3 pg/mg). In 14 cases positive results were obtained for both segments. In one sample a positive result was obtained for segment A but not for segment B and in a further two samples only for segment B. The results indicate that EtG analyses can be performed on mummy hair samples even several hundred years after death to identify evidence for significant alcohol consumption during life. PMID:24053883

Musshoff, Frank; Brockmann, Christopher; Madea, Burkhard; Rosendahl, Wilfried; Piombino-Mascali, Dario

2013-10-10

11

Practical experiences in application of hair fatty acid ethyl esters and ethyl glucuronide for detection of chronic alcohol abuse in forensic cases  

Microsoft Academic Search

This article presents results from 1872 hair samples, which were analyzed for fatty acid ethyl esters (FAEEs) and ethyl glucuronide (EtG). The results were evaluated in the context of self-reported drinking behavior, the use of hair cosmetics, the gender of the sample donors and hair sample length. For comparison, CDT and GGT in serum were available in 477 and 454

S. Suesse; F. Pragst; T. Mieczkowski; C. M. Selavka; A. Elian; H. Sachs; M. Hastedt; M. Rothe; J. Campbell

12

Immunoassay for ethyl glucuronide in vitreous humor: a new tool for postmortem diagnostics of alcohol use.  

PubMed

Although excessive alcohol consumption plays a major role in fatal events, the role of alcohol use as a possible contributing factor at the time of death is not easy to establish due to lack of suitable biomarkers for postmortem analyses. We used an immunological approach to measure ethyl glucuronide (EtG) concentrations from vitreous humor (VH) and serum from 58 individuals representing a forensic autopsy population of cases with either a well-documented history of excessive alcohol use (n=37) or cases without such history (n=21), according to medical and police records and blood alcohol determinations (BAC). The immunoassay was based on the Microgenics DRI-EtG EIA reagents applied on an automated Abbott Architect c8000 clinical chemistry analyzer. Liquid chromatography-tandem mass spectrometry (LC-MS/MS) determination of EtG and ethyl sulfate (EtS) was used as a reference method. At a cut-off of 0.3mg/l for VH-EtG, the immunoassay correctly identified 92% of the cases with a history of excessive alcohol use, whereas the BAC was positive (cut-off 10mg/dl) in 68% of the cases. A significant correlation emerged between VH-EtG and serum EtG (r=0.77, p<0.001) and between VH-EtG and BAC (r=0.62, p<0.001), although VH-EtG was frequently elevated also in cases with no detectable BAC. The EtG immunoassay showed a strong correlation with the LC-MS/MS reference method (r=0.94, p<0.001) and there was 100% agreement in the frequency of marker positive and negative findings between the immunoassay EtG results and the LC-MS/MS analysis of EtG and EtS. The present data indicate that the immunoassay for VH-EtG is a useful forensic tool for screening of antemortem alcohol use. PMID:23415594

Rainio, Juha; Kultti, Johanna; Kangastupa, Päivikki; Tuomi, Heidi; Ahola, Sanna; Karhunen, Pekka J; Helander, Anders; Niemelä, Onni

2013-03-10

13

Influence of thermal hair straightening on ethyl glucuronide content in hair.  

PubMed

Hair analysis of ethyl glucuronide (EtG) has become a valuable marker for the detection of moderate and chronic alcohol consumption. It has been shown that bleaching and perming may decrease EtG content in hair. So far, no studies exist about the influence of thermal hair straightening on EtG content in hair. Forty-one positive EtG hair samples were treated in vitro with a hair straightener at 200°C. Duration of treatment of 1 min was chosen for this study. After washing, pulverization, incubation in ultrasonic bath, solid-phase extraction, and derivatization with heptafluorobutyric anhydride, EtG was determined by gas chromatography-mass spectrometry - negative ion chemical ionization (GC-MS-NICI). The EtG contents in straightened hair strands were then compared with those in the corresponding untreated strands. In 20 of 41 hair samples, a decrease of EtG content was found ranging from 0.7% to 79.3% (average 20%) whereas in 21 cases an increase was shown ranging from 2.0% to 50.9% (average 15%). The variation of the results seems to depend on hair colour. The decrease may be explained by thermic in vitro destruction of EtG. The increase may be explained by denaturation of the hair matrix by thermal treatment possibly causing a better extraction of EtG during incubation in ultrasonic bath. This in vitro study indicates that thermal hair straightening has an impact on the EtG content in hair. This has to be considered for a correct interpretation of EtG results in hair. However, these results should be confirmed by in vivo studies. PMID:24817051

Ettlinger, Jana; Kirchen, Luc; Yegles, Michel

2014-06-01

14

Ethyl glucuronide in hair and fingernails as a long-term alcohol biomarker  

PubMed Central

Aims This study aimed to evaluate the performance of ethyl glucuronide (EtG) in hair and fingernails as a long-term alcohol biomarker. Design Cross-sectional survey with probability sampling. Setting Midwestern United States. Participants Participants were 606 undergraduate college students between the ages of 18 and 25 years at the time of selection for potential study participation. Measurements EtG concentrations in hair and fingernails were measured by liquid chromatography-tandem mass spectrometry at three thresholds [30 picograms (pg) per milligram (mg); 20 pg/mg; and 8 pg/mg]. Any weekly alcohol use, increasing-risk drinking and high-risk drinking on average during the past 12 weeks was assessed by participant interview using the time-line follow-back method. Findings In both hair and fingernails at all three EtG thresholds, sensitivity was greatest for the high-risk drinking group [hair: 0.43, confidence interval (CI) = 0.17, 0.69 at 30 pg/mg, 0.71, CI = 0.47, 0.95 at 20 pg/mg; 0.93, CI = 0.79, 1.00 at 8 pg/mg; fingernails: 1.00, CI = 1.00–1.00 at 30, 20 and 8 pg/mg] and specificity was greatest for any alcohol use (hair: 1.00, CI = 1.00, 1.00 at 30 and 20 pg/mg; 0.97, CI = 0.92–0.99 at 8 pg/mg; fingernails: 1.00, CI = 1.00–1.00 at 30, 20 and 8 pg/mg). Areas under the receiver operating characteristic curves were significantly higher for EtG concentration in fingernails than hair for any weekly alcohol use (P = 0.02, DeLong test, two-tailed) and increasing-risk drinking (P = 0.02, DeLong test, two-tailed). Conclusions Ethyl glucuronide, especially in fingernails, may have potential as a quantitative indicator of alcohol use. PMID:24524319

Berger, Lisa; Fendrich, Michael; Jones, Joseph; Fuhrmann, Daniel; Plate, Charles; Lewis, Douglas

2014-01-01

15

Rearranged glucuronic acid conjugates of bilirubin-IX alpha in post-obstructive bile. Structure elucidation of azopigments beta and gamma as ethyl anthranilate N-glycosides derived from 2-, 3- and 4-o-acyl glucuronides.  

PubMed

Azopigment analysis was performed on conjugates of bilirubin-IXalpha in bile of man and rats obtained after obstruction of the bile duct or in bile incubated under N2. The azopigments beta and gamma, formed by applying a pH 2.7 diazonium reagent containing an excess of ethyl anthranilate, correspond to rearranged ethyl athranilate N-glucuronides having the azodipyrrole acyl group on positions 2, 3 and 4 of the sugar. These assignments were verified, first by conversion of the structurally known 2-, 3- and 4-O-acyl glucuronide azopigments, unsubstituted at C-1, into ethyl anthranilate N-glucuronide reference compounds, and second, by mass spectrometry of trimethylsilyl ether methyl ester derivatives of unknown and reference compounds. The C-1 ethyl anthranilate group of the N-glucuronides triggers characteristics fragmentation reactions of the carbohydrate moiety revealing the position of the azodipyrrole O-acyl group. PMID:678617

Compernolle, F; Van Hees, G P; Heirwegh, K P

1978-07-01

16

Ethyl glucuronide concentrations in two successive urinary voids from drinking drivers: relationship to creatinine content and blood and urine ethanol concentrations  

Microsoft Academic Search

The concentrations of alcohol in blood (BAC) and two successive urine voids (UAC) from 100 drunk drivers were compared with the concentration of ethyl glucuronide (EtG), a minor metabolite of ethanol in urine, and the urinary creatinine content as an indicator of dilution. The subjects consisted of 87 men with mean age 42.2±14.2 years (±standard deviation, S.D.) and 13 women

J Bergström; A Helander; A. W Jones

2003-01-01

17

Do drug users use less alcohol than non-drug users? A comparison of ethyl glucuronide concentrations in hair between the two groups in medico-legal cases  

Microsoft Academic Search

Two groups were selected from the remainder of hair samples that had been tested for drugs at TrichoTech for medico-legal cases: samples that tested negative (drug-negative group; N=42, age 33.4±7.2 years) and samples that tested positive for drugs (drug-positive group; N=57, age 32.5±8.8 years).A rapid, simple method to detect the ethanol metabolite, ethyl glucuronide (EtG) in hair has been developed.

Richard Paul; Robert Kingston; Lolita Tsanaclis; Anthony Berry; Alan Guwy

2008-01-01

18

An evaluation of washing and extraction techniques in the analysis of ethyl glucuronide and fatty acid ethyl esters from hair samples.  

PubMed

Ethyl glucuronide (EtG) and fatty acid ethyl esters (FAEEs) are alcohol metabolites measured in hair and are after a decade of research thought to be the best markers in hair to indicate alcoholism and abstinence Forensic Sci. Int. 218 (2012) 2. A great body of work concerning EtG and FAEEs detection in hair has been performed. However, no recent extensive comparison has been made concerning washing and extraction procedures. This work shows that the washing procedure of dichloromethane followed by a methanol rinse of the hair sample removes more than 16% of the FAEEs and 50% of the total EtG that is present in and on the hair. A review of ten washing protocols (where the removal is categorised: high, medium or low) showed that a relatively high percentage of FAEEs was removed and "medium" amount of EtG compared to the other washing protocols. This work shows promising results for the extraction of the FAEEs and the combined extraction of FAEEs and EtG by using 30min of sonication with methanol. More FAEEs were recovered from hair with methanol than with any other extraction solvent including the commonly used dimethyl sulfoxide/heptane mixture. When the sonication time was increased a higher percentage of transesterification of the FAEEs was observed, the extraction was "dirtier" as solids and a colour change was observed whereas the extraction efficiency did not increase. Therefore, washing the hair sample with dichloromethane and methanol followed by an addition of 1ml of methanol and sonication for 30min to extract the FAEEs and EtG from hair is recommended for FAEEs as well as for the combined analysis of EtG and FAEEs. A linear calibration curve (r(2)>0.99) was obtained for all analytes. PMID:24590191

Bossers, L C A M; Paul, R; Berry, A J; Kingston, R; Middendorp, C; Guwy, A J

2014-03-15

19

Validation of a novel method to identify in utero ethanol exposure: simultaneous meconium extraction of fatty acid ethyl esters, ethyl glucuronide, and ethyl sulfate followed by LC-MS/MS quantification.  

PubMed

Presence of fatty acid ethyl esters (FAEE), ethyl glucuronide (EtG), and ethyl sulfate (EtS) in meconium, the first neonatal feces, identifies maternal alcohol consumption during pregnancy. Current meconium alcohol marker assays require separate analyses for FAEE and EtG/EtS. We describe development and validation of the first quantitative liquid chromatography tandem mass spectrometry assay for 9 FAEEs, EtG, and EtS in 100 mg meconium. For the first time, these alcohol markers are analyzed in the same meconium aliquot, enabling comparison of the efficiency of gestational ethanol exposure detection. 100 mg meconium was homogenized in methanol and centrifuged. The supernatant was divided, and applied to two different solid phase extraction columns for optimized analyte recovery. Limits of quantification for ethyl laurate, myristate, linolenate, palmitoleate, arachidonate, linoleate, palmitate, oleate, and stearate ranged from 25-50 ng/g, with calibration curves to 2,500-5,000 ng/g. EtG and EtS linear dynamic ranges were 5-1,000 and 2.5-500 ng/g, respectively. Mean bias and between-day imprecision were <15 %. Extraction efficiencies were 51.2-96.5 %. Matrix effects ranged from -84.7 to 16.0 %, but were compensated for by matched deuterated internal standards when available. All analytes were stable (within ±20 % change from baseline) in 3 authentic positive specimens, analyzed in triplicate, after 3 freeze/thaw cycles (-20 °C). Authentic EtG and EtS also were stable after 12 h at room temperature and 72 h at 4 °C; some FAEE showed instability under these conditions, although there was large inter-subject variability. This novel method accurately detects multiple alcohol meconium markers and enables comparison of markers for maternal alcohol consumption. PMID:24408304

Himes, Sarah K; Concheiro, Marta; Scheidweiler, Karl B; Huestis, Marilyn A

2014-03-01

20

The influence of cleansing shampoos on ethyl glucuronide concentration in hair analyzed with an optimized and validated LC-MS/MS method.  

PubMed

Ethyl glucuronide (EtG) is widely used as a marker for assessment of alcohol consumption behavior. In this study the influence of special cleansing shampoos on ethyl glucuronide concentrations in hair was investigated. For that purpose an optimized LC-MS/MS method was developed using a Hypercarb™ porous graphitic carbon (PGC) column and validated according to the guidelines of the German Society of Toxicological and Forensic Chemistry (GTFCh). Twenty-five hair samples of persons with known alcohol consumption behavior were investigated (21 positive samples and 4 blank samples). The hair samples were divided into two strands of hair and were analyzed after treatment with one out of four cleansing shampoos and without shampoo treatment. EtG concentrations in hair did not show any significant differences after a single application of the different cleansing shampoos. EtG was still detectable in all the positive hair samples without significant concentration change. These results clearly demonstrated that a single application of the tested cleansing shampoos did not remove EtG from hair and therefore had no influence on EtG concentration in analytical hair analysis. PMID:25151107

Binz, Tina M; Baumgartner, Markus R; Kraemer, Thomas

2014-11-01

21

Regiospecificity of Human UDP-glucuronosyltransferase Isoforms in Chalcone and Flavanone Glucuronidation Determined by Metal Complexation and Tandem Mass Spectrometry  

PubMed Central

The glucuronidation of a series of chalcones (2'-hydroxychalcone, 2',4'-dihydroxychalcone, 3,2'-dihydroxychalcone, 4,2'-dihydroxychalcone, and cardamonin) and their corresponding cyclized flavanones (7-hydroxyflavanone, 3'-hydroxyflavanone, 4'-hydroxyflavanone, and alpinetin) by nine human UDP-glucuronosyltransferase (UGT) 1A enzymes was evaluated. A post-column metal complexation LC-MS/MS strategy was used successfully to produce characteristic mass spectrometric product ions that were utilized in combination with elution order trends to identify chalcone and flavanone monoglucuronides unambiguously, thus allowing determination of the regioselectivities of the UGT1A isoforms. The presence of hydroxy groups on the A or B-ring had a significant effect on the glucuronide product yield and the site where glucuronidation occurred. For example, for reaction with UGT1A9, formation of the 2'-O-glucuronide was increased for dihydroxychalcones with A-ring hydroxy substituents. In contrast, although UGT1A8 reacted with 3,2'-dihydroxychalcone and 4,2'-dihydroxychalcone to yield 2'-O-glucuronide products, the presence of a B-ring hydroxy group at the 4' position on cardamonin and 2',4'-dihydroxychalcone quenched the reaction at the OH-2' position. Moreover, the A-ring OH-4 group promoted glucuronidation at the 2' position for the reaction of 4,2'-dihydroxychalcone with UGT1A1 and 1A3. For UGT1A7, hydroxy group substituents on the chalcone A-ring also promoted cyclization and formation of the corresponding flavanone glucuronide. PMID:23713759

Niemeyer, Emily D.; Brodbelt, Jennifer S.

2013-01-01

22

A Validated Method for Simultaneous Determination of Codeine, Codeine-6-Glucuronide, Norcodeine, Morphine, Morphine-3-Glucuronide and Morphine-6-Glucuronide in Post-Mortem Blood, Vitreous Fluid, Muscle, Fat and Brain Tissue by LC-MS.  

PubMed

The toxicodynamics and, to a lesser degree, toxicokinetics of the widely used opiate codeine remain a matter of controversy. To address this issue, analytical methods capable of providing reliable quantification of codeine metabolites alongside codeine concentrations are required. This article presents a validated method for simultaneous determination of codeine, codeine metabolites codeine-6-glucuronide (C6G), norcodeine and morphine, and morphine metabolites morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) in post-mortem whole blood, vitreous fluid, muscle, fat and brain tissue by high-performance liquid chromatography mass spectrometry. Samples were prepared by solid-phase extraction. The validated ranges were 1.5-300 ng/mL for codeine, norcodeine and morphine, and 23-4,600 ng/mL for C6G, M3G and M6G, with exceptions for norcodeine in muscle (3-300 ng/mL), morphine in muscle, fat and brain (3-300 ng/mL) and M6G in fat (46-4,600 ng/mL). Within-run and between-run accuracy (88.1-114.1%) and precision (CV 0.6-12.7%), matrix effects (CV 0.3-13.5%) and recovery (57.8-94.1%) were validated at two concentration levels; 3 and 150 ng/mL for codeine, norcodeine and morphine, and 46 and 2,300 ng/mL for C6G, M3G and M6G. Freeze-thaw and long-term stability (6 months at -80°C) was assessed, showing no significant changes in analyte concentrations (-12 to +8%). The method was applied in two authentic forensic autopsy cases implicating codeine in both therapeutic and presumably lethal concentration levels. PMID:25556373

Frost, Joachim; Løkken, Trine N; Brede, Wenche R; Hegstad, Solfrid; Nordrum, Ivar S; Slørdal, Lars

2015-04-01

23

Capillary electrophoresis-mass spectrometry determination of morphine and its isobaric glucuronide metabolites.  

PubMed

The determination of morphine and its isobaric metabolites morphine-3-beta-d-glucuronide (M3G) and morphine-6-beta-d-glucuronide (M6G) is useful for therapeutic drug monitoring and forensic identification of drug use. In particular, capillary electrophoresis with mass spectrometry (CE-MS) represents an attractive tool for opioid analysis. Whereas volatile background electrolytes in CE often improve electrospray ionization for coupled MS detection, such electrolytes may reduce CE separation efficiency and resolution. To better understand the effects of background electrolyte (BGE) composition on separation efficiency and detection sensitivity, this work compares and contrasts method development for both volatile (ammonium formate and acetate) and nonvolatile (ammonium phosphate and borate) buffers. Peak efficiencies and migration times for morphine and morphine metabolites were optimal with a 25mM ammonium borate buffer (pH=9.5) although greater sensitivities were achieved in the ammonium formate buffer. Optimized CE methods allowed for the resolution of the isobaric morphine metabolites prior to high mass accuracy, electrospray ionization quadrupole time-of-flight (ESI-QTOF) MS detection applicable to the analysis of urine samples in under seven minutes. Urine sample preparation required only a 10-fold dilution with BGE prior to analysis. Limits of detection (LOD) in normal human urine were found to be 1.0?g/mL for morphine and 2.5?g/mL for each of M3G and M6G by CE-ESI-QTOF-MS. These LODs were comparable to those for CE-UV analysis of opioid standards in buffer, whereas CE-ESI-QTOF-MS analysis of opioid standards in buffer yielded LODs an order of magnitude lower. Patient urine samples (N=12) were analyzed by this new CE-ESI-QTOF-MS method and no significant difference in total morphine content relative to prior liquid chromatography-mass spectrometry (LC-MS) results was found as per a paired-t test at the 99% confidence level. Whereas the LC-MS method applied to these samples determined only total morphine content, this new CE-ESI-QTOF-MS method allowed for species differentiation in addition to total morphine determination. By this method, it was found that M3G and M6G metabolites were present in a 5:1 concentration ratio, on average, in patient samples. Therefore, the CE-ESI-QTOF-MS method not only allows for total morphine concentration determination comparable to established LC-MS methods, but also allows for differentiation between morphine and its trace glucuronides, yielding additional biochemical information about drug metabolism. PMID:25589256

Isbell, Theresa A; Strickland, Erin C; Hitchcock, Jennifer; McIntire, Gregory; Colyer, Christa L

2015-02-01

24

Separatory determination of diastereomeric ibuprofen glucuronides in human urine by liquid chromatography/electrospray ionization-mass spectrometry.  

PubMed

A method for the separatory determination of diastereomeric isomers of glucuronic acid conjugates of ibuprofen having a carboxyl group at the chiral center by liquid chromatography (LC)/electrospray ionization (ESI)-mass spectrometry (MS) has been developed. The authentic specimens of acyl glucuronides of R(-)- and S(+)-ibuprofen were chemically synthesized by the Mitsunobu reaction. In the ESI mode, the glucuronides were characterized by an abundant quasi-molecular ion [M-H]-, and the formation of the negative ion was markedly influenced by a drift voltage. The resolution of diastereomeric isomers was achieved on a Develosil ODS-HG-5 column with 20 mM ammonium acetate (pH 5.0):acetonitrile (5:2, v/v) as a mobile phase where diastereomers were monitored with a corresponding quasi-molecular ion. After oral administration of racemic ibuprofen, a preferential excretion of (S)-ibuprofen glucuronide into the urine was observed. PMID:9861489

Ikegawa, S; Murao, N; Oohashi, J; Goto, J

1998-01-01

25

Determination of fatty acid ethyl esters in hair by GC–MS and application in a population of cocaine users  

Microsoft Academic Search

A gas chromatography–mass spectrometry method for the determination of ethyl myristate, ethyl palmitate, ethyl oleate, and ethyl stearate in hair samples was developed, validated and applied to real samples. Ethyl myristate, ethyl palmitate, ethyl oleate, and ethyl stearate are fatty acid ethyl esters (FAEE) which are known to be direct biotransformation products of ethanol. Their presence in the body fluids

Lucia Politi; Francesco Mari; Sandra Furlanetto; Ester Del Bravo; Elisabetta Bertol

2011-01-01

26

Validation of a sequential extraction and liquid chromatography-tandem mass spectrometric method for determination of dihydrotestosterone, androstanediol and androstanediol-glucuronide in prostate tissues.  

PubMed

Androgens are key mediators of prostate development and function, a role that extends to the development of prostate diseases such as benign prostatic hyperplasia (BPH) and prostate cancer. In prostate, DHT is the major androgen and reduction and glucuronidation are the major metabolic pathways for DHT elimination. A streamlined method for quantitation of dihydrotestosterone (DHT), 5?-androstan-3?,17?-diol (3?-diol), and 3?-diol glucuronide (diol-gluc) was established and validated for use with archived prostate tissue specimens to facilitate examination of the roles of the underlying metabolism. This involved a sequential 70/30 hexane/ethyl acetate (hex/EtOAc) extraction of steroids, followed by an ethyl acetate extraction for diol-gluc. Derivatization of the hex/EtOAc fraction with2-fluoro-1-methylpyridinium p-toluene-4-sulfonate (FMP) was used to enhance sensitivity for hydroxyl steroids and liquid chromatography-tandem mass spectrometry (LC-MS/MS) was utilized for analysis of both fractions. The method was validated with calibration standards followed by recovery assessment from spiked samples of BPH and normal prostate. Lower limits of quantitation (LLOQ) were 50 pg/g, 20 pg/g and 100 pg/g for DHT, 3?-diol and diol-gluc, respectively for extracts from 50mg equivalents of tissue. Prepared samples were stable for up to three weeks at 4 °C and 37 °C. The method provides excellent sensitivity and selectivity for determination of tissue levels of DHT, 3?-diol, and diol-gluc. Furthermore, this protocol can easily be extended to other hydroxyl steroids, is relatively straightforward to perform and is an effective tool for assessing steroid levels in archived clinical prostate samples. PMID:22818945

Adomat, Hans H; Bains, Onkar S; Lubieniecka, Joanna M; Gleave, Martin E; Guns, Emma S; Grigliatti, Thomas A; Reid, Ronald E; Riggs, K Wayne

2012-08-01

27

Micellar electrokinetic capillary chromatography method for direct determination of glucuronides of entacapone and its (Z)-isomer in human urine.  

PubMed

This paper describes the validation of a micellar electrokinetic capillary chromatography method for the direct determination of the 3-O-glucuronides of entacapone and its (Z)-isomer, the main urinary metabolites of entacapone in humans. Entacapone is a novel drug which, as a potent inhibitor of catechol-O-methyltransferase (COMT), is used as an adjunct in the standard therapy of Parkinson's disease. The 3-O-glucuronide of another COMT inhibitor, nitecapone, was used as internal standard (I.S.). The validation experiments were performed by using spiked urine samples that were extracted with Sep-Pak C18 cartridges before analysis. Determinations were carried out in a buffer of pH 7.0 containing 25 mM of phosphate, 50 mM of borate and 20 mM of sodium dodecyl sulfate, and by applying 15 kV over a 67 cm (60 cm to the detector) x 75 microns fused-silica capillary. UV detection was at 335 nm. The validity of the method was assessed by investigating the identity of the analytes, selectivity, limit of quantitation, linearity, within-day precision, extraction recovery, between-day precision and accuracy, electroosmotic flow stability and analyte stability. The method proved to be reproducible, sufficiently selective and accurate. Extraction recoveries of the analytes were > 94%. The limit of quantitation (LOQ) was 2 micrograms/ml and the assay was linear in the range 2-150 micrograms/ml with correlation coefficients better than 0.999 for both glucuronides. The repeatability of the method, expressed as the ratio of corrected peak area of the analytes to that of I.S., gave RSD values of < 5% even at the LOQ. Between-day precision (RSD) was < 7.5% for both glucuronides at 7.5 micrograms/ml. Determination of the glucuronide concentrations in urine samples of 34 patients treated with entacapone either orally (200 mg) or intravenously (25 mg) showed the method to be suitable for monitoring the concentrations of the glucuronide of entacapone after both oral and intravenous administration and those of the glucuronide of its (Z)-isomer after oral administration. The limited long term stability of the system requires, however, frequent recalibration in applications involving long sample series. PMID:10220913

Lehtonen, P; Lehtinen, S; Mälkki-Laine, L; Wikberg, T

1999-03-19

28

Select steroid hormone glucuronide metabolites can cause toll-like receptor 4 activation and enhanced pain.  

PubMed

We have recently shown that several classes of glucuronide metabolites, including the morphine metabolite morphine-3-glucuronide and the ethanol metabolite ethyl glucuronide, cause toll like receptor 4 (TLR4)-dependent signaling in vitro and enhanced pain in vivo. Steroid hormones, including estrogens and corticosterone, are also metabolized through glucuronidation. Here we demonstrate that in silico docking predicts that corticosterone, corticosterone-21-glucuronide, estradiol, estradiol-3-glucuronide and estradiol-17-glucuronide all dock with the MD-2 component of the TLR4 receptor complex. In addition to each docking with MD-2, the docking of each was altered by pre-docking with (+)-naloxone, a TLR4 signaling inhibitor. As agonist versus antagonist activity cannot be determined from these in silico interactions, an in vitro study was undertaken to clarify which of these compounds can act in an agonist fashion. Studies using a cell line transfected with TLR4, necessary co-signaling molecules, and a reporter gene revealed that only estradiol-3-glucuronide and estradiol-17-glucuronide increased reporter gene product, indicative of TLR4 agonism. Finally, in in vivo studies, each of the 5 drugs was injected intrathecally at equimolar doses. In keeping with the in vitro results, only estradiol-3-glucuronide and estradiol-17-glucuronide caused enhanced pain. For both compounds, pain enhancement was blocked by the TLR4 antagonist lipopolysaccharide from Rhodobacter sphaeroides, evidence for the involvement in TLR4 in the resultant pain enhancement. These findings have implications for several chronic pain conditions, including migraine and temporomandibular joint disorder, in which pain episodes are more likely in cycling females when estradiol is decreasing and estradiol metabolites are at their highest. PMID:25218902

Lewis, Susannah S; Hutchinson, Mark R; Frick, Morin M; Zhang, Yingning; Maier, Steven F; Sammakia, Tarek; Rice, Kenner C; Watkins, Linda R

2015-02-01

29

Autism and Phthalate Metabolite Glucuronidation  

PubMed Central

Exposure to environmental chemicals may precipitate autism spectrum disorders (ASD) in genetically susceptible children. Differences in the efficiency of the glucuronidation process may substantially modulate substrate concentrations and effects. To determine whether the efficiency of this pathway is compromised in children with ASD, we measured the efficiency of glucuronidation for a series of metabolites derived from the commonly used plasticizer, diethylhexyl phthalate. Spot urines were collected and analyzed for the fraction of each metabolite conjugated by isotope dilution-liquid chromatography mass spectrometry-mass spectrometry. The degree of glucuronidation was lower with the ASD group. The glucuronidation pathway may differ in some children with ASD. PMID:23575644

Schluter, Margaret D.; Steer, Robert A.; Ming, Xue

2013-01-01

30

Quantitative determination of common urinary odorants and their glucuronide conjugates in human urine.  

PubMed

Our previous study on the identification of common odorants and their conjugates in human urine demonstrated that this substance fraction is a little-understood but nonetheless a promising medium for analysis and diagnostics in this easily accessible physiological medium. Smell as an indicator for diseases, or volatile excretion in the course of dietary processes bares high potential for a series of physiological insights. Still, little is known today about the quantitative composition of odorous or volatile targets, as well as their non-volatile conjugates, both with regard to their common occurrence in urine of healthy subjects, as well as in that of individuals suffering from diseases or other physiological misbalancing. Accordingly, the aim of our study was to develop a highly sensitive and selective approach to determine the common quantitative composition of selected odorant markers in healthy human subjects, as well as their corresponding glucuronide conjugates. We used one- and two-dimensional high resolution gas chromatography-mass spectrometry in combination with stable isotope dilution assays to quantify commonly occurring and potent odorants in human urine. The studies were carried out on both native urine and on urine that had been treated by glucuronidase assays, with analysis of the liberated odor-active compounds using the same techniques. Analytical data are discussed with regard to their potential translation as future diagnostic tool. PMID:24958143

Wagenstaller, Maria; Buettner, Andrea

2013-01-01

31

Identifying and applying a highly selective probe to simultaneously determine the O-glucuronidation activity of human UGT1A3 and UGT1A4  

PubMed Central

Glucuronidation mediated by uridine 5?-diphospho (UDP)-glucuronosyltransferase is an important detoxification pathway. However, identifying a selective probe of UDP- glucuronosyltransferase is complicated because of the significant overlapping substrate specificity displayed by the enzyme. In this paper, desacetylcinobufagin (DACB) 3-O- and 16-O-glucuronidation were found to be isoform-specific probe reactions for UGT1A4 and UGT1A3, respectively. DACB was well characterized as a probe for simultaneously determining the catalytic activities of O-glucuronidation mediated by UGT1A3 and UGT1A4 from various enzyme sources, through a sensitive analysis method. PMID:25884245

Jiang, Li; Liang, Si-Cheng; Wang, Chao; Ge, Guang-Bo; Huo, Xiao-Kui; Qi, Xiao-Yi; Deng, Sa; Liu, Ke-Xin; Ma, Xiao-Chi

2015-01-01

32

Direct gradient reversed-phase high-performance liquid chromatographic determination of salicylic acid, with the corresponding glycine and glucuronide conjugates in human plasma and urine.  

PubMed

A gradient reversed-phase HPLC analysis for the direct measurement of salicylic acid (SA) with the corresponding glycine and glucuronide conjugates in plasma and urine of humans was developed. The glucuronides were isolated by preparative HPLC from human urine samples. The concentration of the glucuronides in the isolated fraction were determined after enzymatic hydrolysis. Salicylic acid acyl glucuronide (SAAG) was not present in plasma. No isoglucuronides were present in acidic and alkaline urine of the volunteer. The limits of quantitation in plasma are: SA 0.2 microgram/ml, salicyluric acid (SU) 0.1 microgram/ml, salicylic acid phenolic glucuronide (SAPG) 0.4 microgram/ml and salicyluric acid phenolic glucuronide (SUPG) 0.2 microgram/ml. The limit of quantitation in urine is for all compounds 5 micrograms/ml. Salicylic acid acyl glucuronide is stable in phosphate buffer pH 4.9 during 8 h at 37 degrees C; thereafter it declines to 80% after 24 h. The subject's urine was therefore acidified by the oral intake of 4 x 1.2 g of ammonium chloride/day. With acidic urine, hardly any salicylic acid is excreted unchanged (0.6%). It is predominantly excreted as salicyluric acid (68.7%). PMID:8006100

Vree, T B; van Ewijk-Beneken Kolmer, E W; Verwey-van Wissen, C P; Hekster, Y A

1994-02-11

33

Direct determination of glucuronide and sulfate of 4-hydroxy-3-methoxymethamphetamine, the main metabolite of MDMA, in human urine  

Microsoft Academic Search

A sensitive and reliable LC-ESI–MS procedure for the simultaneous determination of MDMA and its five metabolites including 4-hydroxy-3-methoxymethamphetamine (HMMA) conjugates has been established following the synthesis of two HMMA conjugates, 4-hydroxy-3-methoxymethamphetamine-glucuronide (HMMA-Glu) and 4-hydroxy-3-methoxymethamphetamine-sulfate (HMMA-Sul). Pretreatment of urine samples with methanol and LC–MS employing a C18 semi-micro column with a gradient elution program provided the successful separations and MS determinations

Noriaki Shima; Hiroe Kamata; Munehiro Katagi; Hitoshi Tsuchihashi; Tsutomu Sakuma; Nobuo Nemoto

2007-01-01

34

Determination of sulfates and glucuronides of endogenic steroids in biofluids by high-performance liquid chromatography/orbitrap mass spectrometry  

NASA Astrophysics Data System (ADS)

the possibility of selective determination of testosterone and epitestosterone glucuronides in urine by high-performance liquid chromatography/high-resolution mass spectrometry using solid phase microextraction on a meps cartridge was studied. the effect of the biological matrix on the spectra of conjugated steroids can be taken into account by using the spectra of conjugates recorded for urine samples after hydrolysis as reference spectra. the conditions of fragmentation in the ion source were optimized for separate analytes. this method was used for analyzing real samples with different testosterone/epitestosterone ratios. variations in conjugate contents and qualitative changes in the steroid profile of endogenic compounds were observed.

Semenistaya, E. N.; Virus, E. D.; Rodchenkov, G. M.

2009-04-01

35

Simultaneous determination of bilirubin and its glucuronides in liver microsomes and recombinant UGT1A1 enzyme incubation systems by HPLC method and its application to bilirubin glucuronidation studies.  

PubMed

Bilirubin, an important endogenous substances and liver function index in humans, is primarily eliminated via UGT1A1-catalyzed glucuronidation. Instability of bilirubin and its glucuronides brings substantial technical challenges to conduct in vitro bilirubin glucuronidation assay. In the present study, we developed a simple and robust HPLC method for simultaneous determination of unconjugated bilirubin (UCB) and its multiple glucuronides, i.e. bilirubin monoglucuronides (BMGs, including BMG1 and BMG2 isomers) and diglucuronide (BDG) in rat liver microsomes (RLM), human liver microsomes (HLM) and recombinant human UGT1A1 enzyme (UGT1A1) incubation systems, and applied it to study in vitro bilirubin glucuronidation. UCB, BMG1, BMG2, BDG and their isomers in the incubation mixtures were successfully separated using a C18 column with UV detection at 450nm and mobile phase consisted of 0.1% formic acid in water and acetonitrile by a linear gradient elution program. Assay linearities of bilirubin were confirmed in the range 0.01-2?M. Precision of UCB, BMG1, BMG2 and BDG (n=5) at low, medium and high concentration was within the range of RSD 0.4-3.7%, accuracy expressed in the mean assay recoveries of them (n=5) ranged from 92.8±1.5% to 104.3±2.2% for intra- and inter-day assays and the mean extraction recoveries of them (n=5) were above 91.5±1.0%. Stability of bilirubin and its glucuronides was satisfactory at 37°C in the incubation solutions during the reaction (30min), 25°C for 24h and -70°C for 7d in the processed incubation samples with methanol. Furthermore, we established stable, reliable in vitro incubation systems and optimized the incubation conditions to characterize the kinetics of bilirubin glucuronidation by RLM, HLM and UGT1A1, respectively. The kinetic parameters of formation of total bilirubin glucuronides (TBG, the sum of BMG1, BMG2 and BDG) were as follows: Km of 0.45±0.016, 0.40±0.022, 0.44±0.018?M, Vmax of 2.65±0.057, 1.86±0.029, 2.95±0.036nmol/mg/min, CLint of 5.92±0.22, 4.70±0.079, 6.72±0.27mL/mg/min by RLM, HLM and UGT1A1, respectively. Bilirubin glucuronidation obeyed the Hill equation by RLM and the Michaelis-Menten equation by HLM and UGT1A1 in the range of substrate concentration selected, respectively. In addition, the relative proportions between BDG and BMGs were in connection with enzyme sources (e.g. RLM, HLM and UGT1A1) and bilirubin concentration. PMID:24525562

Ma, Guo; Lin, Jiayuan; Cai, Weimin; Tan, Bo; Xiang, Xiaoqiang; Zhang, Ying; Zhang, Peng

2014-04-01

36

Steroid and steroid glucuronide profiles in urine during pregnancy determined by liquid chromatography-electrospray ionization-tandem mass spectrometry.  

PubMed

An ultra performance liquid chromatography-electrospray ionization-tandem mass spectrometry (UPLC-MS/MS) method was developed for the analysis of steroids and their glucuronides in urine samples. The method provides high sensitivity and fast analysis, as both steroids and their glucuronides can be analyzed directly without hydrolysis or complex sample preparation. The method was applied in profiling of targeted and nontargeted steroids and steroid glucuronides during pregnancy. The concentrations of 11 of 27 targeted steroids and steroid glucuronides and the concentrations of 25 nontargeted steroid glucuronides increased about 10-400 fold during the pregnancy. The concentrations of most of these 36 compounds began to increase in the first days of the pregnancy, increased gradually during the pregnancy, achieved a maximum in late pregnancy, and decreased sharply after delivery. Exceptionally, the concentrations of allopregnanolone and 17-hydroxypregnenolone started to increase later than those of the other steroids. Moreover, the concentrations of E2 glucuronides began to decrease one week before the delivery, in contrast to most of the steroids and steroid glucuronides, whose concentrations dropped sharply during the delivery. Concentrations of 34 compounds decreased noticeably when the subject was on sick leave owing a series of painful contractions. The results suggest that steroids and especially steroid glucuronides may provide a valuable diagnostic tool to follow the course of pregnancy. PMID:24176505

Jäntti, Sirkku E; Hartonen, Minna; Hilvo, Mika; Nygren, Heli; Hyötyläinen, Tuulia; Ketola, Raimo A; Kostiainen, Risto

2013-11-13

37

Determination of acetone and methyl ethyl ketone in water  

USGS Publications Warehouse

Analytical procedures for the determination of acetone and methyl ethyl ketone in water samples were developed. Concentrations in the milligram-per-liter range were determined by injecting an aqueous sample into the analysis system through an injection port, trapping the organics on Tenax-GC at room temperature, and thermally desorbing the organics into a gas chromatograph with a flame ionization detector for analysis. Concentrations in the microgram-per-liter range were determined by sweeping the headspace vapors over a water sample at 50C, trapping on Tenax-GC, and thermally desorbing the organics into the gas chromatograph. The precision for two operators of the milligram-per-liter concentration procedure, expressed as the coefficient of variation, was generally less than 2 percent for concentrations ranging from 16 to 160 milligrams per liter. The precision from two operators of the microgram-per-liter concentration procedure was between 2 and 4 percent for concentrations of 20 and 60 micrograms per liter. (Woodard-USGS)

Tai, D.Y.

1978-01-01

38

Determination of Serotonin and Dopamine Metabolites in Human Brain Microdialysis and Cerebrospinal Fluid Samples by UPLC-MS/MS: Discovery of Intact Glucuronide and Sulfate Conjugates  

PubMed Central

An UPLC-MS/MS method was developed for the determination of serotonin (5-HT), dopamine (DA), their phase I metabolites 5-HIAA, DOPAC and HVA, and their sulfate and glucuronide conjugates in human brain microdialysis samples obtained from two patients with acute brain injuries, ventricular cerebrospinal fluid (CSF) samples obtained from four patients with obstructive hydrocephalus, and a lumbar CSF sample pooled mainly from patients undergoing spinal anesthesia in preparation for orthopedic surgery. The method was validated by determining the limits of detection and quantification, linearity, repeatability and specificity. The direct method enabled the analysis of the intact phase II metabolites of 5-HT and DA, without hydrolysis of the conjugates. The method also enabled the analysis of the regioisomers of the conjugates, and several intact glucuronide and sulfate conjugates were identified and quantified for the first time in the human brain microdialysis and CSF samples. We were able to show the presence of 5-HIAA sulfate, and that dopamine-3-O-sulfate predominates over dopamine-4-O-sulfate in the human brain. The quantitative results suggest that sulfonation is a more important phase II metabolism pathway than glucuronidation in the human brain. PMID:23826355

Suominen, Tina; Uutela, Päivi; Ketola, Raimo A.; Bergquist, Jonas; Hillered, Lars; Finel, Moshe; Zhang, Hongbo; Laakso, Aki; Kostiainen, Risto

2013-01-01

39

Autism and Phthalate Metabolite Glucuronidation  

ERIC Educational Resources Information Center

Exposure to environmental chemicals may precipitate autism spectrum disorders (ASD) in genetically susceptible children. Differences in the efficiency of the glucuronidation process may substantially modulate substrate concentrations and effects. To determine whether the efficiency of this pathway is compromised in children with ASD, we measured…

Stein, T. Peter; Schluter, Margaret D.; Steer, Robert A.; Ming, Xue

2013-01-01

40

Identification of ractopamine glucuronides and determination of bioactive ractopamine residues and its metabolites in food animal urine by ELISA, LC-MS/MS and GC-MS.  

PubMed

Ractopamine glucuronides have been identified in cattle urine sampled by LC-MS/MS. An ELISA method, which was capable of specifically determining (1R, 3R)-ractopamine stereoisomer and its glucuronide metabolites, had more than 100% recovery with an acceptable coefficient of variation in the inter- and intra-assay variation tests for RR-ractopamine. The concentration levels of parent ractopamine and ractopamine glucuronide metabolites as the main components of total ractopamine in cattle and sheep urine showed similar depletion trends, in which the concentration curves increased and reached a climax during the feeding period, and then dropped quickly when entering the withdrawal period. Data from the three methods had very good pair-wise correlations. In the cattle urine samples, the correlation coefficient (R(2)) for parent ractopamine between the ELISA and the LC-MS/MS or GC-MS results were 0.93 or 0.92; R(2) values for parent ractopamine and total ractopamine data measured by LC-MS/MS and GC-MS were 0.9651 and 0.9677, respectively. All R(2) values for data gained from sheep urine samples were >0.95. The study indicated that the close levels of RR-ractopamine stereoisomer in cattle and sheep urine samples may imply the presence of a similar depletion pattern in other livestock, and thus would facilitate an accurate detection and management of ractopamine usage in food safety. PMID:24444392

Jiang, Xiao-Fei; Zhu, Yue-Hui; Liu, Xiao-Yun

2014-01-01

41

Simultaneous determination of three glucuronide conjugates of scutellarein in rat plasma by LC-MS/MS for pharmacokinetic study of breviscapine.  

PubMed

A selective and sensitive LC-MS/MS method was developed and validated for simultaneous determination of three glucuronide conjugates of scutellarein in rat plasma. Plasma samples were pretreated by protein precipitation with acetonitrile. The analytes (scutellarin, scutellarein-6,7-di-O-?-d-glucuronide and scutellarein-6-O-?-d-glucuronide), together with internal standard (IS, baicalin) were separated on a Diamonsil C18 column (150 mm × 4.6 mm, 5 ?m) with an isocratic mobile phase consisting of methanol-water-formic acid (55:45:0.2, v/v/v). Mass spectrometric detection was performed by selected reaction monitoring (SRM) mode via electrospray ionization source operating in negative ionization mode. The method was linear for all the analytes over the investigated concentration ranges with correlation coefficients greater than 0.9954. The intra- and inter-day precisions were less than 9.1% and the relative error was between -1.7% and 4.2%. The extraction recoveries of the analytes and IS from rat plasma were over 63%. The validated method has been successfully applied to a pharmacokinetic study of breviscapine in rats after intragastric administration at a dose of 20mg/kg. The pharmacokinetic results would be helpful to better understand the pharmacological actions of breviscapine. PMID:24999248

Wang, Xin; Xia, Hongjun; Liu, Youping; Qiu, Feng; Di, Xin

2014-08-15

42

Quantitative determination of free and total bisphenol A in human urine using labeled BPA glucuronide and isotope dilution mass spectrometry.  

PubMed

Bisphenol A (BPA) is a widely used industrial chemical in the manufacturing of polycarbonate plastic bottles, food and beverage can linings, thermal receipts, and dental sealants. Animal and human studies suggest that BPA may disrupt normal hormonal function and hence, potentially, have negative effects on the human health. While total BPA is frequently reported, it is recognized that free BPA is the biologically active form and is rarely reported in the literature. The objective of this study was to develop a sensitive and improved method for the measurement of free and total BPA in human urine. Use of a labeled conjugated BPA (bisphenol A-d6 ?-D-glucuronide) allowed for the optimization of the enzymatic reaction and permitted an accurate determination of the conjugated BPA concentration in urine samples. In addition, a (13)C12-BPA internal standard was used to account for the analytical recoveries and performance of the isotope dilution method. Solid-phase extraction (SPE) combined with derivatization and analysis using a triple quadrupole GC-EI/MS/MS system achieved very low method detection limit of 0.027 ng/mL. BPA concentrations were measured in urine samples collected during the second and third trimesters of pregnancy in 36 Canadian women. Total maternal BPA concentrations in urine samples ranged from not detected to 9.40 ng/mL (median, 1.21 ng/mL), and free BPA concentrations ranged from not detected to 0.950 ng/mL (median, 0.185 ng/mL). Eighty-six percent of the women had detectable levels of conjugated BPA, whereas only 22 % had detectable levels of free BPA in their urine. BPA levels measured in this study agreed well with data reported internationally. PMID:24817354

Kubwabo, Cariton; Kosarac, Ivana; Lalonde, Kaela; Foster, Warren G

2014-07-01

43

Chemical synthesis of bilirubin glucuronide conjugates.  

PubMed

In dimethylformamide, the two carboxyl groups of bilirubin react with the bifunctional coupling agent, carbonyldimidazole, to form bilirubin diimidazole, which was isolated and crystallised. The bilirubin diimidazole, termed "activated bilirubin", was shown to react spontaneously with primary alcohols to form diesters of bilirubin. After addition of the tetrabutyl ammonium salt of glucuronic acid, compounds with chromatographic mobilities similar to those of bilirubin mono- and diglucuronides from bile were formed. Bilirubin diglucuronides were isolated by barium precipitation followed by solvent extraction. The bilirubin diglucuronides were considered to be a mixture of alpha and beta glucuronides esterified at positions 1,2,3, or 4 of glucuronic acid because the compound(s) was resistant to hydrolysis with glucuronidase and gave multiple sponts by chromatography after diazotization with ethyl anthranilate. The model compounds lauryl glucuronides were synthesized similarly; the most polar product by chromatography and had identical chromatographic mobility to synthetic lauryl 1-D-glucuronide prepared by reductive debenzylation of lauryl (benzyl (2,3,4-tri-O-benzyl))-D-glucuronide. It is concluded that bilirubin-1-di-beta-D-glucuronide can be synthesized when suitable protecting groups for the 2, 3, and 4 hydroxyl groups of glucuronic acid become available. PMID:1009109

Thompson, R P; Hofmann, A F

1976-11-18

44

Direct determination of diazepam and its glucuronide metabolites in human whole blood by ?Elution solid-phase extraction and liquid chromatography-tandem mass spectrometry.  

PubMed

A ?Elution solid-phase extraction (SPE) liquid chromatography-tandem mass spectrometry (LC-MS/MS) method for simultaneous determination of diazepam, nordiazepam, oxazepam, oxazepam glucuronide, temazepam and temazepam glucuronide in human whole blood is presented. 200 ?L of whole blood samples were loaded onto a Waters Oasis HLB 96-well ?Elution SPE plate using 75 ?L of methanol as the elution solvent, and the eluents were injected into an Eclipse XDB C18 column. No hydrolysis, solvent transfer, evaporation or reconstitution was involved in the sample preparation procedures. Tandem mass spectrometric detection with Turbo Ion Spray was conducted via multiple reaction monitoring (MRM) under positive ionization mode. The method was validated and proved to be accurate (accuracy within 93-108%), precise (intra-day RSD<9.9% and inter-day RSD<7.2%) and sensitive with limits of detection (LOD) in the range of 0.05-0.25 ng/mL for all the compounds. Extraction recoveries were in the range of 31-80% for all the analytes. This method demonstrated to be reproducible and reliable. The applicability of the method was demonstrated by analysis of several forensic cases involving diazepam and its metabolites. PMID:24314534

Wang, Rong; Wang, Xin; Liang, Chen; Ni, Chunfang; Xiong, Lingjuan; Rao, Yulan; Zhang, Yurong

2013-12-10

45

Involvement of UDP-glucuronosyltransferases UGT1A9 and UGT2B7 in ethanol glucuronidation, and interactions with common drugs of abuse.  

PubMed

Ethyl glucuronide (EtG) determination is increasingly used in clinical and forensic toxicology to document ethanol consumption. The enzymes involved in EtG production, as well as potential interactions with common drugs of abuse, have not been extensively studied. Activities of human liver (HLM), kidney (HKM), and intestinal (HIM) microsomes, as well as of 12 major human recombinant UDP-glucuronosyltransferases (UGTs), toward ethanol (50 and 500 mM) were evaluated in vitro using liquid chromatography-tandem mass spectrometry. Enzyme kinetic parameters were determined for pooled microsomes and recombinant UGTs with significant activity. Individual contributions of UGTs were estimated using the relative activity factor approach, proposed for scaling activities obtained with cDNA-expressed enzymes to HLM. Interaction of morphine, codeine, lorazepam, oxazepam, nicotine, cotinine, cannabinol, and cannabidiol (5, 10, 15 mg/l) with ethanol (1.15, 4.6, 11.5 g/l; i.e., 25, 100, 250 mM) glucuronidation was assessed using pooled HLM. Ethanol glucuronidation intrinsic clearance (Cl(int)) was 4 and 12.7 times higher for HLM than for HKM and HIM, respectively. All recombinant UGTs, except UGT1A1, 1A6, and 1A10, produced EtG in detectable amounts. UGT1A9 and 2B7 were the most active enzymes, each accounting for 17 and 33% of HLM Cl(int), respectively. Only cannabinol and cannabidiol significantly affected ethanol glucuronidation. Cannabinol increased ethanol glucuronidation in a concentration-dependent manner, whereas cannabidiol significantly inhibited EtG formation in a noncompetitive manner (IC(50) = 1.17 mg/l; inhibition constant (K(i)) = 3.1 mg/l). UGT1A9 and 2B7 are the main enzymes involved in ethanol glucuronidation. In addition, our results suggest that cannabinol and cannabidiol could significantly alter ethanol glucuronidation. PMID:23230132

Al Saabi, Alaa; Allorge, Delphine; Sauvage, François-Ludovic; Tournel, Gilles; Gaulier, Jean-Michel; Marquet, Pierre; Picard, Nicolas

2013-03-01

46

Determination of fatty acid ethyl esters in hair by GC-MS and application in a population of cocaine users.  

PubMed

A gas chromatography-mass spectrometry method for the determination of ethyl myristate, ethyl palmitate, ethyl oleate, and ethyl stearate in hair samples was developed, validated and applied to real samples. Ethyl myristate, ethyl palmitate, ethyl oleate, and ethyl stearate are fatty acid ethyl esters (FAEE) which are known to be direct biotransformation products of ethanol. Their presence in the body fluids and tissue is therefore indicative of alcohol intake and, in particular, FAEE concentration in hair higher than 0.5 ng/mg is indicative of excessive chronic alcohol consumption. The method was applied to 80 hair samples formerly found positive for cocaine and FAEE analytical results were compared with the presence of cocaethylene, a cocaine metabolite formed only when alcohol and cocaine are used together. According to our data the two biomarkers (FAEE and cocaethylene in hair) are tools of great value in the assessment of the diagnosis of use of cocaine and ethanol. In fact, discrepancies were noted and might be related to various factors including differences in consumption habits and thus permitting to distinguish the use of both substances non-concurrently or concurrently. Also, the determination of both markers may, in some cases, discriminate the use of moderate or heavy alcohol amounts when associated with cocaine. Finally, in a population of non-cocaine-users our results support FAEE as valuable means in the assessment of excessive alcohol chronic use. PMID:21159458

Politi, Lucia; Mari, Francesco; Furlanetto, Sandra; Del Bravo, Ester; Bertol, Elisabetta

2011-04-01

47

Validation of a Rapid and Sensitive LC-MS/MS Method for Determination of Exemestane and Its Metabolites, 17?-Hydroxyexemestane and 17?-Hydroxyexemestane-17-O-?-D-Glucuronide: Application to Human Pharmacokinetics Study  

PubMed Central

A novel, rapid and sensitive liquid chromatography-tandem mass spectrometric (LC-MS/MS) method was developed and validated for the evaluation of exemestane pharmacokinetics and its metabolites, 17?-dihydroexemestane (active metabolite) and 17?-dihydroexemestane-17-O-?-D-glucuronide (inactive metabolite) in human plasma. Their respective D3 isotopes were used as internal standards. Chromatographic separation of analytes was achieved using Thermo Fisher BDS Hypersil C18 analytic HPLC column (100 × 2.1 mm, 5 ?m). The mobile phase was delivered at a rate of 0.5 mL/min by gradient elution with 0.1 % aqueous formic acid and acetonitrile. The column effluents were detected by API 4000 triple quadrupole mass spectrometer using electrospray ionisation (ESI) and monitored by multiple reaction monitoring (MRM) in positive mode. Mass transitions 297 > 121 m/z, 300 > 121 m/z, 299 > 135 m/z, 302 > 135 m/z, 475 > 281 m/z, and 478 > 284 m/z were monitored for exemestane, exemestane-d3, 17?-dihydroexemestane, 17?-dihydroexemestane-d3, 17?-dihydroexemestane-17-O-?-D-glucuronide, and 17?-dihydroexemestane-17-O-?-D-glucuronide-d3 respectively. The assay demonstrated linear ranges of 0.4 – 40.0 ng/mL, for exemestane; and 0.2 – 15.0 ng/mL, for 17?-dihydroexemestane and 17?-dihydroexemestane-17-O-?-D-glucuronide, with coefficient of determination (r2) of > 0.998. The precision (coefficient of variation) were ?10.7%, 7.7% and 9.5% and the accuracies ranged from 88.8 to 103.1% for exemestane, 98.5 to 106.1% for 17?-dihydroexemestane and 92.0 to 103.2% for 17?-dihydroexemestane-17-O-?-D-glucuronide. The method was successfully applied to a pharmacokinetics/dynamics study in breast cancer patients receiving exemestane 25mg daily orally. For a representative patient, 20.7% of exemestane in plasma was converted into 17?-dihydroexemestane and 29.0% of 17?-dihydroexemestane was inactivated as 17?-dihydroexemestane-17-O-?-D-glucuronide 24 hours after ingestion of exemestane, suggesting that altered 17-dihydroexemestane glucuronidation may play an important role in determining effect of exemestane against breast cancer cells. PMID:25793887

Wang, Ling-Zhi; Goh, Sok-Hwei; Wong, Andrea Li-Ann; Thuya, Win-Lwin; Lau, Jie-Ying Amelia; Wan, Seow-Ching; Lee, Soo-Chin; Ho, Paul C.; Goh, Boon-Cher

2015-01-01

48

[Effect of tacrolimus on the pharmacokinetics and glucuronidation of SN-38, an active metabolite of irinotecan].  

PubMed

The present study has investigated the effect of tacrolimus on the pharmacokinetics of an active metabolite of irinotecan (CPT-11), 7-ethyl-10-hydroxy-camptothecin (SN-38) and SN-38 glucuronide (SN-38G) in rats. The effect of tacrolimus on SN-38 glucuronidation was also investigated in human and rat liver microsomes. When tacrolimus (0.5 mg/kg) was intravenously injected in rats 15 min before intravenous injection of CPT-11 (5 mg/kg), tacrolimus decreased the plasma concentration of SN-38G. Tacrolimus significantly decreased the area under plasma concentration-time curve (AUC) of SN-38G without change in the mean residence time. On the contrary, significant changes in the pharmacokinetic parameters of SN-38 were not observed. SN-38 glucuronidation in human and rat liver microsomes was inhibited dose-dependently by the presence of tacrolimus and the 50% inhibition concentration (IC50) values of tacrolimus in rat and human liver microsomes were 10.33 ?M and 3.58 ?M, respectively. When the inhibition type was determined by Lineweaver-Burk and Dixon plots, the inhibition was noncompetitive and the calculated inhibition constant (Ki) values for rat and human liver microsomes were 12.57 ?M and 3.88 ?M, respectively. These findings suggest that tacrolimus inhibits UGT1A1-mediated SN-38 glucuronidation. Considering the IC50 and Ki values for tacrolimus, it is likely that tacrolimus does not alter the pharmacokinetics of SN-38 and SN-38G at the clinically used dosages, suggesting the possibility that tacrolimus can use safely for cancer patients with irinotecan chemotherapy. PMID:23328499

Tanaka, Yoshiteru; Katoh, Miki; Fujioka, Miho; Onishi, Katsuhiro; Sakakibara, Yukiko; Hasegawa, Takaaki; Nadai, Masayuki

2013-01-01

49

Deconjugation of soy isoflavone glucuronides needed for estrogenic activity.  

PubMed

Soy isoflavones (SIF) are present in the systemic circulation as conjugated forms of which the estrogenic potency is not yet clear. The present study provides evidence that the major SIF glucuronide metabolites in blood, genistein-7-O-glucuronide (GG) and daidzein-7-O-glucuronide (DG), only become estrogenic after deconjugation. The estrogenic potencies of genistein (Ge), daidzein (Da), GG and DG were determined using stably transfected U2OS-ER?, U2OS-ER? reporter gene cells and proliferation was tested in T47D-ER? cells mimicking the ER?/ER? ratio of healthy breast cells and inT47D breast cancer cells. In all assays applied, the estrogenic potency of the aglycones was significantly higher than that of their corresponding glucuronides. UPLC analysis revealed that in U2OS and T47D cells, 0.2-1.6% of the glucuronides were deconjugated to their corresponding aglycones. The resulting aglycone concentrations can account for the estrogenicity observed upon glucuronide exposure. Interestingly, under similar experimental conditions, rat breast tissue S9 fraction was about 30 times more potent in deconjugating these glucuronides than human breast tissue S9 fraction. Our study confirms that SIF glucuronides are not estrogenic as such, and that the small % of deconjugation in the cell is enough to explain the slight bioactivity observed for the SIF-glucuronides. Species differences in deconjugation capacity should be taken into account when basing risk-benefit assessment of these SIF for the human population on animal data. PMID:25661160

Islam, M A; Bekele, R; Vanden Berg, J H J; Kuswanti, Y; Thapa, O; Soltani, S; van Leeuwen, F X R; Rietjens, I M C M; Murk, A J

2015-06-01

50

Polycyclic aromatic hydrocarbons: determinants of urinary 1-hydroxypyrene glucuronide concentration and risk of colorectal cancer in the Shanghai Women’s Health Study  

PubMed Central

Background Associations between polycyclic aromatic hydrocarbons (PAHs) and colorectal cancer have been reported previously but few studies have characterized PAH exposure using biological measurements. We evaluated colorectal cancer risk in relation to urinary concentration of 1-hydroxypyrene glucuronide (1-OHPG), a polycyclic aromatic hydrocarbon (PAH) metabolite, and assessed determinants of PAH exposure among controls in the Shanghai Women’s Health Study (SWHS). Methods Concentrations of 1-OHPG were measured in spot urine samples collected from 343 colorectal cancer cases and 343 individually matched controls. Questionnaires were administered to collect information on demographic characteristics and reported exposures. Odds ratios were calculated for risk of colorectal cancer in relation to quartiles of urinary 1-OHPG concentration. Potential determinants of natural log-transformed urinary 1-OHPG concentration were evaluated among a combined sample of controls from this study and another nested case–control study in the SWHS (Ntotal=652). Results No statistically significant differences in risk of colorectal cancer by urinary 1-OHPG levels were observed. Among controls, the median (interquartile range) urinary 1-OHPG concentration was 2.01 pmol/mL (0.95-4.09). Active and passive smoking, using coal as a cooking fuel, eating foods that were cooked well done, and recent consumption of fried dough (e.g., yóutiáo) were associated with elevated levels of 1-OHPG, though only active smoking and fried dough consumption achieved statistical significance in multivariate analyses. Conclusions This study does not provide evidence of an association between urinary levels of 1-OHPG and risk of colorectal cancer among women. Several environmental and dietary sources of PAH exposure were identified. Overall, the levels of 1-OHPG in this population of predominantly non-smoking women were considerably higher than levels typically observed among non-smokers in Europe, North America, and other developed regions. PMID:23758680

2013-01-01

51

Measurement of bisphenol A, bisphenol A ß-d-glucuronide, genistein, and genistein 4?-ß-d-glucuronide via SPE and HPLC-MS/MS  

PubMed Central

Bisphenol A (BPA) is a synthetic industrial reactant used in the production of polycarbonate plastics, and genistein is a natural phytoestrogen abundant in the soybean. Current studies investigating the endocrinedisrupting effects of concomitant exposures to BPA and genistein have warranted the development of an analytical method for the simultaneous measurement of BPA and genistein, as well as their primary metabolites, bisphenol A ß-d-glucuronide (BPA gluc) and genistein 4?-ß-d-glucuronide (genistein gluc), respectively. All four analytes were extracted from rat plasma via solid phase extraction (SPE). Three SPE cartridges and four elution schemes were tested. Plasma extraction using Bond Elut Plexa cartridges with sequential addition of ethyl acetate, methanol, and acetonitrile yielded optimal average recoveries of 98.1±1.8% BPA, 94.9±8.0% genistein, 91.4±6.1% BPA gluc, and 103±6.1% genistein gluc. Identification and quantification of the four analytes were performed by a validated HPLC-MS/MS method using electrospray ionization and selective reaction monitoring. This novel analytical method should be applicable to the measurement of BPA, genistein, BPA gluc, and genistein gluc in urine, cultures, and tissue following in vivo exposures. While reports of the determination of BPA and genistein independently exist, the simultaneous optimized extraction and detection of BPA, genistein, BPA gluc, and genistein gluc have not previously been reported. PMID:21667348

Coughlin, Janis L.; Winnik, Bozena

2015-01-01

52

Determination of a novel nonfluorinated quinolone, nemonoxacin, in human feces and its glucuronide conjugate in human urine and feces by high-performance liquid chromatography-triple quadrupole mass spectrometry.  

PubMed

Three methods were developed and validated for determination of nemonoxacin in human feces and its major metabolite, nemonoxacin acyl-?-d-glucuronide, in human urine and feces. Nemonoxacin was extracted by liquid-liquid extraction in feces homogenate samples and nemonoxacin acyl-?-d-glucuronide by a solid-phase extraction procedure for pretreatment of both urine and feces homogenate sample. Separation was performed on a C18 reversed-phase column under isocratic elution with the mobile phase consisting of acetonitrile and 0.1% formic acid. Both analytes were determined by liquid chromatography-tandem mass spectrometry with positive electrospray ionization in selected reaction monitoring mode and gatifloxacin as the internal standard. The lower limit of quantitation (LLOQ) of nemonoxacin in feces was 0.12?µg/g and the calibration curve was linear in the concentration range of 0.12-48.00?µg/g. The LLOQ of the metabolite was 0.0010?µg/mL and 0.03?µg/g in urine and feces matrices, while the linear range was 0.0010-0.2000?µg/mL and 0.03-3.00?µg/g, respectively. Validation included selectivity, accuracy, precision, linearity, recovery, matrix effect, carryover, dilution integrity and stability, indicating that the methods can quantify the corresponding analytes with excellent reliability. The validated methods were successfully applied to an absolute bioavailability clinical study of nemonoxacin malate capsule. Copyright © 2014 John Wiley & Sons, Ltd. PMID:25322721

He, Gaoli; Guo, Beining; Yu, Jicheng; Zhang, Jing; Wu, Xiaojie; Cao, Guoying; Shi, Yaoguo; Tsai, Cheng-Yuan

2014-10-17

53

Determining the Partial Photoionization Cross-Sections of Ethyl Radicals B. L. FitzPatrick, M. Maienschein-Cline, and L. J. Butler*  

E-print Network

and the partial photo- ionization cross-sections for dissociative ionization. Decades of research have establishedDetermining the Partial Photoionization Cross-Sections of Ethyl Radicals B. L. FitzPatrick, M. The data determine the relative partial cross-sections for the photoionization of ethyl radicals to form C2

Butler, Laurie J.

54

Glucuronidation of active tamoxifen metabolites by the human UDP glucuronosyltransferases.  

PubMed

Tamoxifen (TAM) is an antiestrogen that has been widely used in the treatment and prevention of breast cancer in women. One of the major mechanisms of metabolism and elimination of TAM and its major active metabolites 4-hydroxytamoxifen (4-OH-TAM) and 4-OH-N-desmethyl-TAM (endoxifen; 4-hydroxy-N-desmethyl-tamoxifen) is via glucuronidation. Although limited studies have been performed characterizing the glucuronidation of 4-OH-TAM, no studies have been performed on endoxifen. In the present study, characterization of the glucuronidating activities of human UDP glucuronosyltransferases (UGTs) against isomers of 4-OH-TAM and endoxifen was performed. Using homogenates of individual UGT-overexpressing cell lines, UGTs 2B7 approximately 1A8 > UGT1A10 exhibited the highest overall O-glucuronidating activity against trans-4-OH-TAM as determined by Vmax/K(M), with the hepatic enzyme UGT2B7 exhibiting the highest binding affinity and lowest K(M) (3.7 microM). As determined by Vmax/K(M), UGT1A10 exhibited the highest overall O-glucuronidating activity against cis-4-OH-TAM, 10-fold higher than the next-most active UGTs 1A1 and 2B7, but with UGT1A7 exhibiting the lowest K(M). Although both N- and O-glucuronidation occurred for 4-OH-TAM in human liver microsomes, only O-glucuronidating activity was observed for endoxifen; no endoxifen-N-glucuronidation was observed for any UGT tested. UGTs 1A10 approximately 1A8 > UGT2B7 exhibited the highest overall glucuronidating activities as determined by Vmax/K(M) for trans-endoxifen, with the extrahepatic enzyme UGT1A10 exhibiting the highest binding affinity and lowest K(M) (39.9 microM). Similar to that observed for cis-4-OH-TAM, UGT1A10 also exhibited the highest activity for cis-endoxifen. These data suggest that several UGTs, including UGTs 1A10, 2B7, and 1A8 play an important role in the metabolism of 4-OH-TAM and endoxifen. PMID:17664247

Sun, Dongxiao; Sharma, Arun K; Dellinger, Ryan W; Blevins-Primeau, Andrea S; Balliet, Renee M; Chen, Gang; Boyiri, Telih; Amin, Shantu; Lazarus, Philip

2007-11-01

55

Simultaneous determination of ezetimibe and its glucuronide metabolite in human plasma by solid phase extraction and liquid chromatography-tandem mass spectrometry.  

PubMed

A liquid chromatography-tandem mass spectrometry method (LC-MS/MS) was developed to quantify ezetimibe (EZM) and its major glucuronide (ezetimibe glucuronide, EZM-G) in human plasma simultaneously. The analytes were puri?ed by solid phase extraction (SPE) without hydrolysis. Separation of the analytes was achieved using acetonitrile-water (0.08% formic acid) (70:30, v/v) as the mobile phase at a flow rate of 0.8mL/min on an Agilent Extend C18 column. The analytes were detected by LC-MS/MS using negative ionization in multiple reaction monitoring (MRM) mode. The mass transition pairs of m/z 408.4?271.0 and m/z 584.5?271.0 were used to detect EZM and EZM-G, respectively. The analytical method was linear over the concentration range of 0.1-20ng/mL for EZM and 0.5-200ng/mL for EZM-G. Within- and between-run precision for EZM was no more than 8.6% and 12.8%; and for EZM-G was no more than 9.0% and 8.7%, respectively. This method was reproducible and reliable, and was successfully used to analyze human plasma samples for application in a bioequivalence study. PMID:25725321

Guo, Lin; Wang, Meng-Meng; He, Min; Qiu, Fu-Rong; Jiang, Jian

2015-04-01

56

Validated LC-MS/MS method for the determination of maackiain and its sulfate and glucuronide in blood: Application to pharmacokinetic and disposition studies  

PubMed Central

The purpose of this study was to develop a simultaneous, sensitive and reproducible UPLC-MS/MS method to quantify maackiain and its phase II metabolites, maackiain-sulfate (M-7-S) and maackiain-glucuronide (M-7-G). A Waters BEH C18 column was used with acetonitrile/water as mobile phases. Analysis was performed under negative ionization electrospray mass spectrometer via the multiple reaction monitoring (MRM). The one-step protein precipitation by methanol was used to extract the analytes from plasma. The results showed that the linear response range was 5000 - 9.75 nM for maackiain, M-7-S, and M-7-G. The lower limit of detection (LLOD) was 4.88 nM for these three analytes. The intra-day variance is less than 15% and accuracy is in 85.7–102.0 %. The inter-day variance is less than 11.2 % and accuracy is in 89.6–122.2 %. The analysis was done within 4.0 min. Only 20 µl of blood is needed for analysis due to the high sensitivity of this method. The validated method was used to pharmacokinetic study in A/J mouse, maackiain Caco-2 cell culture model experiment, and maackiain glucuronidation/ sulfation metabolism studies. The applications revealed that this method can be used for maackiain, M-7-S, and M-7-G analysis in both bioequivalent buffer and in blood. PMID:21349678

Gao, Song; Yang, Zhen; Yin, Taijun; You, Ming; Hu, Ming

2011-01-01

57

LC-MS/MS method for the simultaneous determination of ethyl gallate and its major metabolite in rat plasma.  

PubMed

A simple, rapid and sensitive liquid chromatography-tandem mass spectroscopy (LC-MS/MS) method was developed and validated for the determination of ethyl gallate, a pharmacologically active constituent isolated from Lagerstroemia speciosa (Linn.) Pers. This method was used to examine the pharmacokinetics of ethyl gallate and its major metabolite gallic acid in rat plasma using propyl gallate as an internal standard. After precipitation of the plasma proteins with acetonitrile, the analytes were separated on a Zorbax SB-C(18) column (3.5 microm, 2.1 x 50 mm) with an isocratic mobile phase consisted of methanol-acetonitrile-10 mM ammonium acetate (10 : 25 : 65, v/v/v) containing 0.1% formic acid at a flow rate of 0.25 mL/min. The Agilent G6410A triple quadrupole LC/MS system was operated under the multiple-reaction monitoring mode using the electrospray ionization technique in negative mode. The lower limits of quantification of gallic acid and ethyl gallate of the method were 0.5 and 1.0 ng/mL. The intra-day and inter-day accuracy and precision of the assay were less than 8.0%. This method has been applied successfully to a pharmacokinetic study involving the intragastric administration of ethyl gallate to rats. PMID:19688816

Gao, Shouhong; Zhan, Qin; Li, Jingxian; Yang, Qi; Li, Xia; Chen, Wansheng; Sun, Lianna

2010-05-01

58

Validated LC-MS/MS method for the determination of 3-Hydroxflavone and its glucuronide in blood and bioequivalent buffers: Application to pharmacokinetic, absorption, and metabolism studies  

PubMed Central

The purpose of this study is to develop an UPLC-MS/MS method to quantify 3-hydroxy-flavone (3-HF) and its metabolite, 3-hydroxyflavone-glucuronide (3-HFG) from biological samples. A Waters BEH C8 column was used with acetonitrile/0.1 % formic acid in water as mobile phases. The mass analysis was performed in an API 5500 Qtrap mass spectrometer via multiple reaction monitoring (MRM) with positive scan mood. The one-step protein precipitation by acetonitrile was used to extract the analytes from plasma. The results showed that the linear response range was 0.61– 2,500.00 nM for 3-HF and 0.31– 2,500.00 nM for 3-HFG. The intra-day variance is less 16.48 % and accuracy is in 77.70–90.64 % for 3-HF and variance less than 15.86%, accuracy in 85.08–114.70 % for 3-HFG. The inter-day variance is less than 20.23 %, accuracy is in 110.58–114.2 % for 3-HF and variance less than 15.59 %, accuracy in 83.00–89.40% for 3-HFG. The analysis was done within 4.0 min. Only 10 ?L of blood is needed due to the high sensitivity of this method. The validated method was successfully used to pharmacokinetic study in A/J mouse, transport study in the Caco-2 cell culture model, and glucuronidation study using mice liver and intestine microsomes. The applications revealed that this method can be used for 3-HF and 3-HFG analysis in blood as well as in bioequivalent buffers such HBSS and KPI. PMID:23973631

Xu, Beibei; Yang, Guanyi; Ge, Shufan; Yin, Taijun; Hu, Ming; Gao, Song

2015-01-01

59

Validated LC-MS/MS method for the determination of 3-hydroxflavone and its glucuronide in blood and bioequivalent buffers: application to pharmacokinetic, absorption, and metabolism studies.  

PubMed

The purpose of this study is to develop an UPLC-MS/MS method to quantify 3-hydroxyflavone (3-HF) and its metabolite, 3-hydroxyflavone-glucuronide (3-HFG) from biological samples. A Waters BEH C8 column was used with acetonitrile/0.1% formic acid in water as mobile phases. The mass analysis was performed in an API 5500 Qtrap mass spectrometer via multiple reaction monitoring (MRM) with positive scan mood. The one-step protein precipitation by acetonitrile was used to extract the analytes from blood. The results showed that the linear response range was 0.61-2500.00 nM for 3-HF and 0.31-2500.00 nM for 3-HFG. The intra-day variance is less than 16.5% and accuracy is in 77.7-90.6% for 3-HF and variance less than 15.9%, accuracy in 85.1-114.7% for 3-HFG. The inter-day variance is less than 20.2%, accuracy is in 110.6-114.2% for 3-HF and variance less than 15.6%, accuracy in 83.0-89.4% for 3-HFG. The analysis was done within 4.0 min. Only 10 ?l of blood is needed due to the high sensitivity of this method. The validated method was successfully used to pharmacokinetic study in A/J mouse, transport study in the Caco-2 cell culture model, and glucuronidation study using mice liver and intestine microsomes. The applications revealed that this method can be used for 3-HF and 3-HFG analysis in blood as well as in bioequivalent buffers such HBSS and KPI. PMID:23973631

Xu, Beibei; Yang, Guanyi; Ge, Shufan; Yin, Taijun; Hu, Ming; Gao, Song

2013-11-01

60

Absolute quantification of UGT1A1 in various tissues and cell lines using isotope label-free UPLC-MS/MS method determines its turnover number and correlates with its glucuronidation activities.  

PubMed

Uridine 5'-diphosphate-glucuronosyltransferase (UGT)1A1 is a major phase II metabolism enzyme responsible for glucuronidation of drugs and endogenous compounds. The purpose of this study was to determine the expression level of UGT1A1 in human liver microsomes and human cell lines by using an isotope label-free LC-MS/MS method. A Waters Ultra performance liquid chromatography (UPLC) system coupled with an API 5500Qtrap mass spectrometer was used for the analysis. Two signature peptides (Pep-1, and Pep-2) were employed to quantify UGT1A1 by multiple reaction monitoring (MRM) approach. Standard addition method was used to validate the assay to account for the matrix effect. 17?-Estradiol was used as the marker substrate to determine UGT1A1 activities. The validated method has a linear range of 200-0.0195nM for both signature peptides. The precision, accuracy, and matrix effect were in acceptable ranges. UGT1A1 expression levels were then determined using 8 individual human liver microsomes, a pooled human liver microsomes, three UGT1A1 genotyped human liver microsomes, and four cell lines (Caco-2, MCF-7, Hela, and HepG2). The correlations study showed that the UGT1A1 protein levels were strongly correlated with its glucuronidation activities in human liver microsomes (R(2)=0.85) and in microsomes prepared from cell lines (R(2)=0.95). Isotope-labeled peptides were not necessary for LC-MS/MS quantitation of proteins. The isotope label-free absolute quantification method used here had good accuracy, sensitivity, linear range, and reproducibility, and were used successfully for the accurate determination of UGT1A1 from tissues and cell lines. PMID:24055854

Xu, Beibei; Gao, Song; Wu, Baojian; Yin, Taijun; Hu, Ming

2014-01-01

61

In vitro and in vivo glucuronidation of midazolam in humans  

PubMed Central

AIMS Midazolam (MDZ) is a benzodiazepine used as a CYP3A4 probe in clinical and in vitro studies. A glucuronide metabolite of MDZ has been identified in vitro in human liver microsome (HLM) incubations. The primary aim of this study was to understand the in vivo relevance of this pathway. METHODS An authentic standard of N-glucuronide was generated from microsomal incubations and isolated using solid-phase extraction. The structure was confirmed using proton nuclear magnetic resonance (NMR) and 1H-13C long range correlation experiments. The metabolite was quantified in vivo in human urine samples. Enzyme kinetic behaviour of the pathway was investigated in HLM and recombinant UGT (rUGT) enzymes. Additionally, preliminary experiments were performed with 1?-OH midazolam (1?-OH MDZ) and 4-OH-midazolam (4-OH MDZ) to investigate N-glucuronidation. RESULTS NMR data confirmed conjugation of midazolam N-glucuronide (MDZG) standard to be on the ?-nitrogen of the imidazole ring. In vivo, MDZG in the urine accounted for 1–2% of the administered dose. In vitro incubations confirmed UGT1A4 as the enzyme of interest. The pathway exhibited atypical kinetics and a substrate inhibitory cooperative binding model was applied to determine Km (46 µM, 64 µM), Vmax (445 pmol min?1 mg?1, 427 pmol min?1 mg?1) and Ki (58 µM, 79 µM) in HLM and rUGT1A4, respectively. From incubations with HLM and rUGT enzymes, N-glucuronidation of 1?-OH MDZ and 4-OH MDZ is also inferred. CONCLUSIONS A more complete picture of MDZ metabolism and the enzymes involved has been elucidated. Direct N-glucuronidation of MDZ occurs in vivo. Pharmacokinetic modelling using Simcyp™ illustrates an increased role for UGT1A4 under CYP3A inhibited conditions. PMID:19371318

Hyland, Ruth; Osborne, Toby; Payne, Anthony; Kempshall, Sarah; Logan, Y Raj; Ezzeddine, Khaled; Jones, Barry

2009-01-01

62

Phenotype-genotype correlation of in vitro SN38 (active metabolite of irinotecan) and bilirubin glucuronidation in human liver tissue with UGT1A1 promoter polymorphism  

Microsoft Academic Search

Background: Hepatic uridine diphosphate glucuronosyltransferase (UGT) isoform 1A1 (UGT1A1) is primarily responsible for the glucuronidation of SN-38 (7-ethyl-10-hydroxycamptothecin), the active metabolite of the anticancer agent irinotecan. UGT1A1, also catalyzing the glucuronidation of bilirubin, has been shown to have reduced activity in Gilbert's syndrome. The presence of an additional TA repeat [(TA)7 TAA] in the TATA sequence of UGT1A1 has been

Lalitha Iyer; Diana Hall; Soma Das; Melissa A. Mortell; Jacqueline Ramírez; Sarang Kim; Anna Di Rienzo; Mark J. Ratain

1999-01-01

63

The chemiluminescence determination of 2-chloroethyl ethyl sulfide using luminol-AgNO3-silver nanoparticles system.  

PubMed

A highly sensitive chemiluminescence (CL) method for the determination of 2-chloroethyl ethyl sulfide (2-CEES) was presented. It was found that 2-chloroethyl ethyl sulfide (2-CEES) could inhibit the CL of the luminol-AgNO3 system in the presence of silver nanoparticles in alkaline solution, which made it applicable for determination of 2-CEES. The presented method is simple, convenient, rapid and sensitive. Under the optimized conditions, the calibration curve was linear in the range of 0.0001-1ngmL(-1), with the correlation coefficient of 0.992; while the limit of detection (LOD), based on signal-to-noise ratio (S/N) of 3, was 6×10(-6)ngmL(-1). Also, the relative standard deviation (RSD, n=5) for determination of 2-CEES (0.50ngmL(-1)) was 3.1%. The method was successfully applied for the determination of 2-CEES in environmental aqueous samples. PMID:25703367

Maddah, Bozorgmehr; Shamsi, Javad; Barsang, Mehran Jam; Rahimi-Nasrabadi, Mehdi

2015-05-01

64

Gas chromatographic-mass spectrometric assay for 6-hydroxymelatonin sulfate and 6-hydroxymelatonin glucuronide in urine  

SciTech Connect

Circulating melatonin is hydroxylated to 6-hydroxymelatonin and excreted in urine as the sulfate and glucuronide conjugates. We extracted these two compounds from urine by using octadecylsilane-bonded silica cartridges to eliminate most of the urea and electrolytes, and silica cartridges to separate the sulfate and glucuronide conjugates. After hydrolyzing the separated conjugates enzymically, we determined the free hydroxymelatonin by gas chromatography-mass spectrometry. Though recoveries were low and variable, we were able to quantify the analyte in the original sample by adding deuterated sulfate and glucuronide conjugates to the urines before extraction.

Francis, P.L.; Leone, A.M.; Young, I.M.; Stovell, P.; Silman, R.E.

1987-04-01

65

[Simultaneous determination of ethyl carbamate and chloropropanols in flavorings by gas chromatography-triple quadrupole tandem mass spectrometry].  

PubMed

A simultaneous determination method for ethyl carbamate (EC) and chloropropanols (3-monochloropropane-1, 2-diol (3-MCPD) and 2-monochloropropane-1, 3-diol (2-MCPD)) in flavorings was developed by gas chromatography-triple quadrupole tandem mass spectrometry (GC-MS/MS). After spiked with internal standard, the sample was extracted by matrix solid-phase dispersion extraction technique with an Extrelut NT column. Hexane was used to wash the fat soluble matrix interferences and then an ethyl acetate-ethyl ether (20: 80, v/v) mixture was added to elute the analytes. The concentrated extract was detected by GC-MS/MS in multiple reaction monitoring (MRM) mode. The limits of detection (LODs) were 2, 5 and 5 microg/kg for EC, 3-MCPD and 2-MCPD, respectively. The linear ranges were 5 - 1 000 microg/kg (r = 0.9997), 10-1000 microg/kg (r = 0.999 1) and 10-1000 microg/kg (r = 0.999 5) for EC, 3-MCPD and 2-MCPD, respectively. In soy sauce, yellow rice wine, salami sauce and flavoring of instant noodle matrices, the recoveries (RSDs, n = 7) in MRM mode at the levels of 20, 100 and 400 microg/kg were 87.7%-104% (4.3%-10.7%), 90.1%-109% (2.6%-10.2%), and 90.9%-103% (3.0%-9.5%), respectively. EC, 3-MCPD and 2-MCPD were found in some real samples of the soy sauce, wine and flavoring of instant noodle. EC or 3-MCPD was found in some of the salami samples. The method is accurate, fast and suitable for the simultaneous determination of EC, 3-MCPD and 2-MCPD in flavorings. PMID:24558851

Xu, Xiaomin; He, Huali; Ruan, Yudi; Huang, Baifen; Zhang, Jingshun; Cai, Zengxuan; Ren, Yiping

2013-11-01

66

Determination of O-ethyl S-2-diisopropylaminoethyl methylphosphonothioate (VX) by thermospray liquid chromatography-mass spectrometry.  

PubMed

The determination of the nerve agent O-ethyl S-2-diisopropylaminoethyl methylphosphonothioate (VX) by thermospray liquid chromatography-mass spectrometry was studied. The solvent system acetonitrile-methanol-0.25 M ammonium acetate was used on a reversed-phase C18 column. By selected ion monitoring at the protonated molecular ion of VX (m/z 268), the predominant peak in its thermospray mass spectrum, an amount of 200 pg could be detected. For the determination of VX in water at levels below 1 ng/ml, preconcentration by C18 cartridges was investigated. The applicability of the method was demonstrated by the determination of VX in spiked river waters. A concentration of 0.1 ng/ml could be detected starting from a water sample of 50 ml. A second application concerned the analysis of water extracts of spiked soil samples. PMID:2090658

Wils, E R; Hulst, A G

1990-12-01

67

Comparative evaluation of ELISA kit and HPLC DAD for the determination of chlorpyrifos ethyl residues in water and sediments.  

PubMed

Enzyme linked immunosorbent assay (ELISA) kit is a versatile, cheap and relatively available tool that can be used in remote areas. In this study, performance of ELISA kit was evaluated in terms of accuracy, recovery, precision, sensitivity, cross reactivity and matrix interference for pesticide residue determination in water and sediment samples. This method was compared with high performance liquid chromatography (HPLC) which is not a commonly available analytical technique for chlorpyrifos ethyl residue analysis in developing countries. The ELISA kit had limits of detection (LOD) of 0.37 µg L(-1) and 0.42 µg Kg(-1) dry weight (dw), for chlorpyrifos ethyl in water and sediment samples, respectively using deionized water and a control sediment sample. Mean percentage recoveries and coefficients of variation (CV) for ELISA kit varied from 96.0±5.8% to 108.0±3.4% for water and sediment samples. Comparison between ELISA and HPLC analysis results using water and sediment samples from Lake Naivasha showed no significant difference in results (p?0.05). Strong correlations (r2=0.9878 water samples and r1=0.9670, p<0.0001 for sediment samples, n=48) were reported between the methods for the two samples analyzed. Bland-Altman bias plot analysis showed that the two methods were in agreement within 95% confidence interval of limits -2.9 to 3.8 and -2.2 to 3.6 for water and sediment, respectively. Given the high sensitivity reported and the obtained acceptable limits of coefficient of variation and percentage recovery, ELISA appears to be a suitable rapid analytical tool in analysis of chlorpyrifos ethyl in water and sediment samples. Results demonstrate comparability to HPLC and could complement conventional tools in regular monitoring program particularly in developing countries. This will hasten results delivery for ecological risk assessment and timely execution of mitigation measures. PMID:24209337

Otieno, P O; Owuor, P O; Lalah, J O; Pfister, G; Schramm, K-W

2013-12-15

68

Use of a post-column immobilized beta-glucuronidase enzyme reactor for the determination of diastereomeric glucuronides of fenoldopam in plasma and urine by high-performance liquid chromatography with electrochemical detection.  

PubMed

A post-column enzyme reactor, containing beta-glucuronidase immobilized on controlled-pore glass beads, was developed for use in the high-performance liquid chromatographic (HPLC) analysis of glucuronide metabolites using electrochemical detection. The reactor performance was evaluated with glucuronide conjugates of the new antihypertensive agent, fenoldopam [6-chloro-2,3,4,5-tetrahydro-1-(4-hydroxyphenyl)-1H-3-benzazepine-7,8-di ol]. These conjugates, which are electrochemically inactive at 0.6 V vs. Ag/AgCl, were separated by HPLC and passed directly into the post-column beta-glucuronidase reactor, which converted the glucuronides to their electrochemically active aglycone, fenoldopam. The enzyme reactor converted greater than 80% of the entering glucuronide to fenoldopam and produced a linear response for fenoldopam glucuronide in the range 0.4-200 ng injected on-column. The reactor performance was optimal when the mobile phase (methanol-acetate buffer) contained 0-25% methanol, but the efficiency gradually declined thereafter until, at 50% methanol, the reactor was inactive. The working pH range for the mobile phase was 5.5-8.0, with a performance optimum at pH 6.0. The reactor displayed marked stability during usage (greater than 4 months) and during storage (greater than 6 months). The reactor did not hydrolyze the 8-O-sulfate conjugate of fenoldopam but did convert the 1(R) and 1(S) diastereomers of fenoldopam-7-O-beta-glucuronide and 1(S)-fenoldopam-8-O-beta-glucuronide to fenoldopam. An assay was developed for 1(R)-fenoldopam-7-O-beta-glucuronide in plasma and urine by using the deschloro, des-4'-hydroxy analogue of fenoldopam glucuronide as the internal standard. The assay was linear in the range 4-1600 ng/ml. The within-day and between-day coefficients of variation for the method were less than 7% at three plasma fenoldopam glucuronide concentrations. PMID:2871034

Boppana, V K; Fong, K L; Ziemniak, J A; Lynn, R K

1986-02-26

69

Icosapent Ethyl  

MedlinePLUS

... weight loss, exercise) to reduce the amount of triglycerides (a fat-like substance) in your blood. Icosapent ... ethyl may work by decreasing the amount of triglycerides and other fats made in the liver.

70

Automated determination of ethyl carbamate in stone-fruit spirits using headspace solid-phase microextraction and gas chromatography-tandem mass spectrometry.  

PubMed

A fully automated procedure using headspace solid-phase microextraction (HS-SPME) followed by gas chromatographic/tandem mass spectrometric (GC/MS/MS) detection was developed for the determination of the toxic contaminant ethyl carbamate (EC) in stone-fruit spirits. After addition of deuterated internal standard, the optimised HS-SPME extraction with carbowax/divinylbenzene fibres (30 min at 70 degrees C) was done applying salting out with sodium chloride in the presence of pH 7 buffer solution. For quantitative analysis the characteristic fragmentations of m/z 74>44 and m/z 62>44 for ethyl carbamate as well as m/z 64>44 for ethyl carbamate-d5 were monitored in the multiple reaction monitoring (MRM) mode using a triple quadrupole instrument. In the validation studies, ethyl carbamate exhibited good linearity with a regression coefficient of 0.998. The limits of detection and quantitation were 0.03 and 0.11 mg/l. The precision never exceeded 4.3% (intraday) and 8.2% (interday) at any of the concentrations examined. A good agreement of analysis results in comparison to conventional sample clean-up over diatomaceous earth columns was found (R = 0.956, Bias = 0.08 mg/l). The new HS-SPME/GC/MS/MS procedure is suitable for the fast, reliable and inexpensive determination of ethyl carbamate in alcoholic beverages in an automated, and therefore, convenient procedure. PMID:16427646

Lachenmeier, Dirk W; Nerlich, Uta; Kuballa, Thomas

2006-03-01

71

Sample cleanup-free determination of mycophenolic acid and its glucuronide in serum and plasma using the novel technology of ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry.  

PubMed

Mycophenolic acid (MPA) is an immunosuppressant drug which powerfully inhibits lymphocyte proliferation. Since the early 1990s it has been used to prevent rejection in organ transplantation. The requirement of therapeutic drug monitoring shown in previous studies raises the necessity of acquiring accurate and sensitive methods to measure MPA and its major metabolite mycophenolic acid glucuronide (MPAG). The authors developed a sample cleanup-free, rapid, and highly specific method for simultaneous measurement of MPA and MPAG in human plasma and serum using the novel technology of ultra-performance liquid chromatography-electrospray ionization tandem mass spectrometry. MPA- and MPAG-determinations were performed during a 2.0-min run time. Multiple calibration curves for the analysis of MPA and MPAG exhibited consistent linearity and reproducibility in the range of 0.05-100 (r>0.999) mg L(-1) and 4-4000 mg L(-1) (r>0.999), respectively. Limits of Detection were 0.014 mg L(-1) for MPA and 1.85 mg L(-1) for MPAG. Lower Limits of Quantification were 0.05 mg L(-1) for MPA and 2.30 mg L(-1) for MPAG. Interassay imprecision was <10% for both substances. Mean recovery was 103.6% (range 78.1-129.7%) for MPA and 111.1% (range 73.0-139.6%) for MPAG. Agreement was good for MPA and MPAG between the presented method and a validated HPLC-MS/MS method. The Passing-Bablok regression line for MPA and MPAG was HPLC-MS/MS=1.14 UPLC-MS/MS-0.14 [ mg L(-1)], r=0.96, and HPLC-MS/MS=0.77 UPLC-MS/MS+0.50 [ mg L(-1)], r=0.97, respectively. This sample cleanup-free and robust LC-MS/MS assay facilitates the rapid, accurate and simultaneous determination of MPA and MPAG in human body fluids. PMID:20152429

Kuhn, Joachim; Götting, Christian; Kleesiek, Knut

2010-03-15

72

Simultaneous determination of propofol and its glucuronide in whole blood by liquid chromatography-electrospray tandem mass spectrometry and the influence of sample storage conditions on the reliability of the test results.  

PubMed

Propofol (2,6-diisopropylphenol) is commonly used as an anaesthetic agent but is also abused for recreational purposes. Several cases of fatalities involving self-administered propofol have been reported. For rapid quantification of propofol and propofol ?-d-glucuronide (propofol G) in clinical and forensic cases, an ultra-performance liquid chromatography-tandem mass spectrometry method using pneumatically assisted electrospray ionisation has been developed. The technique has been validated on both ante-mortem and post-mortem human whole blood. The proteins in the blood samples were removed by the addition of a mixture of methanol and acetonitrile, and the extract was cleaned up by solid phase extraction. The extract was concentrated in dimethyl sulphoxide. The system was calibrated using matrix-matched calibrants combined with isotope dilution. The lower limits of quantification were 0.01 and 0.02mg/L for propofol and 0.02 and 0.04mg/L for propofol G in ante-mortem and post-mortem whole blood, respectively. The relative intra-laboratory reproducibility standard deviation was less than 10% at concentrations of 0.2mg/L or higher. The mean true extraction recovery was 85% for propofol and 81% for propofol G. The trueness of the propofol determination expressed as the relative bias of the test results was within ±6% at concentration levels of 0.01-8.5mg/L. Propofol was less stable in blood stabilised with a citrate-EDTA-fluoride mixture than in blood stabilised with an oxalate-fluoride mixture. The stability was lower at -20°C than at 5°C and -80°C. Propofol G did not show instability under the storage conditions tested. PMID:25770413

Sørensen, Lambert K; Hasselstrøm, Jørgen B

2015-05-10

73

Morphine, morphine-6-glucuronide and morphine-3-glucuronide pharmacokinetics in newborn infants receiving diamorphine infusions.  

PubMed

1. The pharmacokinetics of morphine, morphine-6-glucuronide (M6G) and morphine-3-glucuronide (M3G) were studied in 19 ventilated newborn infants (24-41 weeks gestation) who were given a loading dose of 50 micrograms kg-1 or 200 micrograms kg-1 of diamorphine followed by an intravenous infusion of 15 micrograms kg-1 h-1 of diamorphine. Plasma concentrations of morphine, M3G and M6G were measured during the accrual to steady-state and at steady state of the diamorphine infusion. 2. Following both the 50 micrograms kg-1 or 200 micrograms kg-1 loading doses the mean steady-state plasma concentration (+/- s.d.) of morphine, M3G and M6G were 86 +/- 52 ng ml-1, 703 +/- 400 ng ml-1 and 48 +/- 28 ng ml-1 respectively and morphine clearance was found to be 4.6 +/- 3.2 ml min-1 kg-1. 3. M3G formation clearance was estimated to be 2.5 +/- 1.8 ml min-1 kg-1, and the formation clearance of M6G was estimated to be 0.46 +/- 0.32 ml min-1 kg-1. 4. M3G metabolite clearance was 0.46 +/- 0.60 ml min-1 kg-1, the elimination half-life was 11.1 +/- 11.3 h and the volume of distribution was 0.55 +/- 1.13 l kg-1. M6G metabolite clearance was 0.71 +/- 0.36 ml min-1 kg-1, the elimination half-life was 18.2 +/- 13.6 h and the volume of distribution was 1.03 +/- 0.88 l kg-1. 5. No significant effect of the loading dose (50 micrograms kg-1 or 200 micrograms kg-1) on the plasma morphine or metabolite concentrations or their derived pharmacokinetic parameters was found. 6. We were unable to identify correlations between gestational age of the infants and any of the determined pharmacokinetic parameters. 7. M3G: morphine and M6G: morphine steady-state plasma concentration ratios were 11.0 +/- 10.8 and 0.8 +/- 0.8, respectively. 8. The metabolism of morphine in neonates, in terms of the respective contributions of each glucuronide pathway, was similar to that in adults. PMID:8799518

Barrett, D A; Barker, D P; Rutter, N; Pawula, M; Shaw, P N

1996-06-01

74

Morphine, morphine-6-glucuronide and morphine-3-glucuronide pharmacokinetics in newborn infants receiving diamorphine infusions  

PubMed Central

1The pharmacokinetics of morphine, morphine-6-glucuronide (M6G) and morphine-3-glucuronide (M3G) were studied in 19 ventilated newborn infants(24–41 weeks gestation) who were given a loading dose of 50??g?kg?1 or 200??g?kg?1 of diamorphine followed by an intravenous infusion of 15??g?kg?1?h?1 of diamorphine. Plasma concentrations of morphine, M3G and M6G were measured during the accrual to steady-state and at steady state of the diamorphine infusion. 2Following both the 50??g?kg?1 or 200??g?kg?1 loading doses the mean steady-state plasma concentration (±s.d.) of morphine, M3G and M6G were 86±52?ng?ml?1, 703±400?ng?ml?1 and 48±28?ng?ml?1 respectively and morphine clearance was found to be 4.6±3.2?ml min?1?kg?1. 3M3G formation clearance was estimated to be 2.5±1.8?ml min?1?kg?1, and the formation clearance of M6G was estimated to be 0.46±0.32?ml min?1?kg?1. 4M3G metabolite clearance was 0.46±0.60?ml min?1?kg?1, the elimination half-life was 11.1±11.3?h and the volume of distribution was 0.55±1.13?l?kg?1. M6G metabolite clearance was 0.71±0.36?ml min?1?kg?1, the elimination half-life was 18.2±13.6?h and the volume of distribution was 1.03±0.88?l?kg?1. 5No significant effect of the loading dose (50??g?kg?1 or 200??g?kg?1) on the plasma morphine or metabolite concentrations or their derived pharmacokinetic parameters was found. 6We were unable to identify correlations between gestational age of the infants and any of the determined pharmacokinetic parameters. 7M3G:morphine and M6G:morphine steady-state plasma concentration ratios were 11.0±10.8 and 0.8±0.8, respectively. 8The metabolism of morphine in neonates, in terms of the respective contributions of each glucuronide pathway, was similar to that in adults. PMID:8799518

BARRETT, D. A.; BARKER, D. P.; RUTTER, N.; PAWULA, M.; SHAW, P. N.

1996-01-01

75

Glucuronidation and Covalent Protein Binding of Benoxaprofen and Flunoxaprofen in Sandwich-Cultured Rat and Human Hepatocytes  

PubMed Central

Benoxaprofen (BNX), a nonsteroidal anti-inflammatory drug (NSAID) that was withdrawn because of hepatotoxicity, is more toxic than its structural analog flunoxaprofen (FLX) in humans and rats. Acyl glucuronides have been hypothesized to be reactive metabolites and may be associated with toxicity. Both time- and concentration-dependent glucuronidation and covalent binding of BNX, FLX, and ibuprofen (IBP) were determined by exposing sandwich-cultured rat hepatocytes to each NSAID. The levels of glucuronide and covalent protein adduct measured in cells followed the order BNX > FLX > IBP. These results indicate that 1) BNX-glucuronide (G) is more reactive than FLX-G, and 2) IBP-G is the least reactive metabolite, which support previous in vivo studies in rats. The proportional increases of protein adduct formation for BNX, FLX, and IBP as acyl glucuronidation increased also support the hypothesis that part of the covalent binding of all three NSAIDs to hepatic proteins is acyl glucuronide-dependent. Moreover, theses studies confirmed the feasibility of using sandwich-cultured rat hepatocytes for studying glucuronidation and covalent binding to hepatocellular proteins. These studies also showed that these in vitro methods can be applied using human tissues for the study of acyl glucuronide reactivity. More BNX-protein adduct was formed in sandwich-cultured human hepatocytes than FLX-protein adduct, which not only agreed with its relative toxicity in humans but also was consistent with the in vitro findings using rat hepatocyte cultures. These data support the use of sandwich-cultured human hepatocytes as an in vitro screening model of acyl glucuronide exposure and reactivity. PMID:19773537

Dong, Jennifer Q.

2009-01-01

76

Revolving Door Action of BCRP Facilitates or Controls the Efflux of Flavone Glucuronides from UGT1A9-Overexpressing HeLa Cells  

PubMed Central

Cellular production of flavonoid glucuronides requires the action of both UDP-glucuronosyltransferases (UGT) and efflux transporters since glucuronides are too hydrophilic to diffuse across the cellular membrane. We determined the kinetics of efflux of 13 flavonoid glucuronides using the newly developed HeLa-UGT1A9 cells and correlated them with kinetic parameters derived using expressed UGT1A9. The results indicated that among the seven monohydroxyflavones (HFs), there was moderately good correlation (r2?0.65) between fraction metabolized (fmet) derived from HeLa-UGT1A9 cells and CLint derived from the UGT1A9-mediated metabolism. However, there was weak or no correlation between these two parameters for six dihyroxylflavones (DHFs). Furthermore, there was weak no correlation between various kinetic parameters (Km, Vmax or CLint) for the efflux and the metabolism regardless if we were using 7 HFs, 6 DHFs or a combination thereof. Instead, cellular excretion of many flavonoids glucuronides appears to be controlled by the efflux transporter, and poor affinity of glucuronide to the efflux transporter resulted in major intracellular accumulation of glucuronides to a level that is above the dosing concentration of its aglycone. Hence, the efflux transporters appear to act as the “Revolving Door” to control the cellular excretion of glucuronides. In conclusion, the determination of a flavonoid's susceptibility to glucuronidation must be based on both its susceptibility to glucuronidation by the enzyme and resulting glucuronide's affinity to the relevant efflux transporters, which act as the “Revolving Door(s)” to facilitate or control its removal from the cells. PMID:23402418

Wei, Yingjie; Wu, Baojian; Jiang, Wen; Yin, Taijun; Jia, Xiaobin; Basu, Sumit; Yang, Guangyi; Hu, Ming

2013-01-01

77

Strategies employed to determine the acute aquatic toxicity of ethyl benzene, a highly volatile, poorly water-soluble chemical.  

PubMed

Studies are described in which ethyl benzene (EB) was tested to determine its acute toxicity to three marine organisms, Atlantic silversides (Menidia menidia), mysid shrimp (Mysidopsis bahia), and diatoms (Skeletonema costatum), and to one freshwater algae (Selenastrum capricornutum). The respective 96-hr median lethal concentration (LC50) values and 95% confidence intervals for EB in the flow-through studies with fish and mysid shrimp were 5.1 (4.4-5.7) mg/liter and 2.6 (2.0-3.3) mg/liter. While the 96-hr median effective concentrations (EC50's) for growth inhibition and 95% confidence intervals for the static studies with diatoms and algae were 7.7 (5.9-10.0) mg/liter and 3.6 (1.7-7.6) mg/liter, respectively. Problems were encountered in all four studies as a result of the high volatility and poor water solubility of EB in water and an apparent "salting out" effect noted in seawater. This effect was found particularly true in the diatom and algae studies where the salinity was increased with the addition of culture medium. Measures are described which were used to overcome this stability problem with EB. These included sealing the test systems tight without any air spaces to prevent the collection of EB vapors. Also, increased mixing of EB in the test solutions was found to be essential in the flow-through studies to maintain stable levels. In the case of the diatom and algal studies, since current EPA test guidelines were judged to be inadequate to overcome EB volatility from the test medium, a new closed test system had to be developed and employed, after validation with a nonvolatile reference toxicant in the new and conventional static test systems. The results of these studies indicate that previous reports underestimated the potential acute aquatic toxicity of EB by at least one order of magnitude. The implications of these findings are discussed in relation to the potential environmental impact of EB and the resultant regulatory actions. PMID:7519552

Masten, L W; Boeri, R L; Walker, J D

1994-04-01

78

Stereoselective urinary excretion of S-(-)- and R-(+)-propranolol glucuronide following oral administration of RS-propranolol in Chinese Han subjects  

PubMed Central

AIM: To study the stereoselectivity of phase II glucuronidation metabolism of side-chain propranolol in Chinese Han population. METHODS: Sixteen adult Chinese Han volunteers with an average age of 20 years were given a single oral dose of 20 mg racemic propranolol. Human urine at indicated time after administration was collected and S-(-)-propranolol glucuronide and R-(+)-propranolol glucuronide were determined simultaneously by using RP-HPLC. RESULTS: The mean values of k were 0.19±0.04 h-1 and 0.28±0.06 h-1, of t1/2 3.56±0.73 h and 2.45±0.50 h, of Tmax 2.21±0.45 and 1.75±0.33 h, and of Xu0-24 5.65±0.98 and 2.95±0.62 ?moL for S-(-)- and R-(+)-propranolol glucuronide, respectively. The cumulative excretion percentages in urine of doses were 14.7±2.46% and 7.68±1.60% for S-(-)- and R-(+)-propranolol glucuronide, respectively. The results showed the elimination rate constant k of S-(-)-propranolol glucuronide was less than that of R-(+)-propranolol glucuronide; and the elimination half-life (t1/2), Tmax and the cumulative excretion amount(Xu0-24) of R-(+)-propranolol glucuronide were significantly less than that of S-(-)-propranolol glucuronide. CONCLUSION: The propranolol glucuronidation of the side-chain undergoes stereoselective excretion in Chinese Han population after an oral administration of racemic propranolol. PMID:15793873

Luan, Lian-Jun; Shao, Qing; Ma, Jian-Yin; Zeng, Su

2005-01-01

79

Migrants determination and bioaccessibility study of ethyl lauroyl arginate (LAE) from a LAE based antimicrobial food packaging material.  

PubMed

Ethyl lauroyl arginate (LAE, ethyl-N-dodecanoyl-L-arginate hydrochloride) is a strong antimicrobial agent that was included as an active compound in an antimicrobial food packaging material. The potential existence of non-intentionally added substances (NIASs) such as impurities must therefore be checked before launching any food contact material onto the market. For this reason, an untargeted analysis of the migration was performed in both food simulants and fresh chicken breast fillets wrapped with the active material. The analysis was performed by liquid chromatography coupled to mass spectrometry detection with a quadrupole-time-of-flight analyzer, LC-MS(QTOF), for the identification of nonvolatile substances. The migration values found for LAE were 0.94±0.14 and 1.62±0.70 ?g/g in ethanol 10% v/v (simulant A) and in ethanol 95% v/v (simulant D), respectively, and 0.93±0.17 ?g/g in chicken. Other migrants such as dipropylene glycol methyl ether or tributyl-o-acetylcitrate, both coming from the coating were also found, but none of them have potential adverse effects. Bioaccessibility studies showed that after a simulated gastrointestinal digestion, LAE was not available anymore for subsequent intestinal absorption and new toxic compounds were not formed. PMID:23485618

Aznar, M; Gómez-Estaca, J; Vélez, D; Devesa, V; Nerín, C

2013-06-01

80

Prediction of glucuronidated drug clearance in pediatrics (?5 years): An allometric approach.  

PubMed

Children are not small adults. The differences between children of different age groups and adults are not merely due to body weight, but also due to physiological and biochemical differences resulting in different rates of drug metabolism or renal clearance. Glucuronidation is an important pathway of drug metabolism. Therefore, the objective of this study is to evaluate the predictive performance of several allometric exponents in children of ?5 years for the total clearance of drugs which are mainly metabolized by glucuronidation. Four exponents (0.75, 1.0, 1.2, or 1.4) on the body weights and an allometric model developed from adults were evaluated. The four exponents and the allometric model were examined to determine the suitability of the method(s) to predict the clearances of drugs which are glucuronidated in children ?5 years of age. Based on the analysis of ten drugs, it was noted that the combination of two allometric exponents 1.2 (for children ?3 months) and 1.0 (for children ?3 months ?5 years) can be used to predict mean clearances of drugs which are mainly metabolized by glucuronidation. The suggested approach may be used to estimate a first-in-pediatric dose to initiate a pediatric clinical trial. PMID:24519316

Mahmood, Iftekhar

2015-03-01

81

Glucuronidation and Sulfation Kinetics of Diflunisal in Man.  

NASA Astrophysics Data System (ADS)

Diflunisal is a nonsteroidal anti-inflammatory drug used in the treatment of arthritis and musculoskeletal pain. Diflunisal exhibits concentration- and dose-dependent kinetics, the mechanism of which has not been determined. The purpose of this study was to determine the mechanism(s) responsible for non-linear disposition of diflunisal and to examine environmental factors which may affect the elimination of diflunisal. The metabolites of diflunisal, including a new metabolite, the sulphate conjugate, were purified by column and semi-preparative high pressure liquid chromatography. Assays for the quantitation of diflunisal and conjugates in urine and diflunisal in plasma were developed. Plasma protein binding of diflunisal in blank plasma and in plasma obtained following multiple doses of diflunisal was determined by equilibrium dialysis. Total body clearance of diflunisal decreased when dose increased from 100 to 750 mg. Total clearance increased when dose increased from 750 to 1000 mg. The percent of recovered dose eliminated as the acyl glucuronide decreased and the percent eliminated as the sulphate increased with increasing dose of diflunisal. Plasma protein binding of diflunisal was concentration dependent over a range of diflunisal plasma concentrations of 3 to 257 mug/ml. Total clearance, and to a lesser degree, unbound clearance of diflunisal were decreased following multiple dose administration of 250 and 500 mg diflunisal. Percent of recovered dose eliminated as the acyl glucuronide decreased and percent eliminated as the sulphate conjugate increased following multiple dosing. Plasma protein binding of diflunisal was similar in blank plasma and plasma obtained at steady state. Unbound clearance of diflunisal exceeded liver plasma flow. Frequency distributions of the elimination of the conjugates of diflunisal were normally distributed. Sex, smoking, and use of vitamins or oral contraceptives were identified as factors which may affect the elimination of diflunisal.

Loewen, Gordon Rapheal

82

Investigation of the substrate specificity of a cloned expressed human bilirubin UDP-glucuronosyltransferase: UDP-sugar specificity and involvement in steroid and xenobiotic glucuronidation.  

PubMed Central

A cloned human bilirubin UDP-glucuronosyltransferase (UGT) stably expressed in Chinese hamster V79 cells was used to assess the substrate specificity of the enzyme. The catalytic potential (Vmax/Km(bilirubin) of the enzyme with UDP-glucuronic acid (UDPGA) was 2-fold and 10-fold greater than that for UDP-xylose and UDP-glucose respectively. The formation of bilirubin mono- and di-conjugates was found to be dependent on time, UDP-sugar concentration and bilirubin concentration. Ex vivo studies demonstrated that the genetically engineered cell line was capable of the uptake and glucuronidation of bilirubin and the release of bilirubin glucuronide, indicating its usefulness in studying transport processes. Over 100 compounds, including drugs, xenobiotics and endogenous steroids, were tested as substrates for the enzyme to determine the chemical structures accepted as substrates. A wide diversity of xenobiotic compounds such as phenols, anthraquinones and flavones (many of which are in foodstuffs) were glucuronidated by the enzyme. The enzyme also had the capacity to glucuronidate oestriols and oestradiols stereoselectively. H.p.l.c. analysis of the regioselective glucuronidation of beta-oestradiol (E2) demonstrated that it was conjugated solely at its A-ring hydroxy group by the bilirubin UGT to form E2-3-glucuronide, this was in contrast with human liver microsomes which formed 3- and 17-glucuronides of this oestrogen. Studies utilizing microsomes from a Crigler-Najjar patient and inhibition of E2 glucuronidation with bilirubin indicated that the cloned expressed bilirubin UGT was the major human UGT isoform responsible for the formation of E2-3-glucuronide, which is the predominant E2 conjugate in human urine. PMID:7945246

Senafi, S B; Clarke, D J; Burchell, B

1994-01-01

83

Determination of carbamate, phenylurea and phenoxy acid herbicide residues by gas chromatography after potassium tert-butoxide/dimethyl sulphoxide/ethyl iodide derivatization reaction.  

PubMed

The usefulness of the potassium tert-butoxide/dimethyl sulphoxide/ethyl iodide reaction with carbamate and phenylurea herbicides, and its application to phenoxy acids as a way to prevent hazards and toxicity of the sodium hydride/dimethyl sulphoxide/methyl iodide reaction was studied. Using factorial design optimization of this reaction was carried out. A solid-phase extraction method using dimethyl sulphoxide as eluent on-line with this reaction was developed to determine these herbicides in water samples by gas chromatography-mass spectrometry. Relative standard deviation values were lower than 10% for most of the herbicides in multicomponent trace determinations. Detection limits were in the 0.110-0.652 ng L(-1) concentration range. The validity of the method was confirmed by recovery studies from natural water samples. PMID:18823898

Crespo-Corral, E; Santos-Delgado, M J; Polo-Díez, L M; Soria, A C

2008-10-31

84

Simultaneous determination of organotin compounds in textiles by gas chromatography-flame photometry following liquid/liquid partitioning with tert-butyl ethyl ether after reflux-extraction.  

PubMed

A rapid and relatively clean method for determining six organotin compounds (OtC) in textile goods with a gas chromatograph equipped with a conventional flame photometric detector (GC-FPD) has been developed. After the reflux-extraction to use methanol containing 1% (v/v) of hydrochloric acid, five hydrophobic OtC (e.g. tributyltin: TBT) and slightly less hydrophobic dibutyltin (DBT) could be drawn out through partitioning between the methanolic buffer solution and tert-butyl ethyl ether instead of hazardous dichloromethane, of which usage is provided by the official-methods notified in Japan, and following the ethylation procedure to use sodium tetraethylborate, the OtC were determined with the GC-FPD. The recoveries of DBT, TBT, tetrabutyltin, triphenyltin, dioctyltin, and trioctyltin from textile products (cloth diaper, socks, and undershirt) were 60-77, 89-98, 86-94, 71-78, 85-109, and 70-79% respectively, and their coefficients of variation were 2.5-16.5%. Calibration curves for OtC were linear (0.01-0.20 ?g as Sn mL(-1)), and the correlation coefficients were 0.9922-1.0000. Their detection limits were estimated to be 2.7-9.7 n gas Sn g(-1). These data suggested that this method would be applicable to their simultaneous determination. Five retailed textile goods were analyzed by this proposed method, and 0.013-0.65 µg as Sn g(-1) of OtC (e.g. DBT) were determined in three. Moreover, a possibility that various OtC including non-targeted species in textile would be specifically detected by applying the studying speciation-technique of controlling signal intensity-flame fuel gas pressures of the GC-FPD was found. PMID:24054605

Hamasaki, Tetsuo

2013-10-15

85

Characterization of Chrysin Glucuronidation in UGT1A1-Overexpressing HeLa Cells: Elucidating the Transporters Responsible for Efflux of Glucuronide.  

PubMed

Active transport of glucuronide out of cells is a critical process in elimination of drugs via the glucuronidation pathway. Here, HeLa cells were stably transfected with UGT1A1 and the contributions of BCRP and MRP family transporters to the cellular efflux of chrysin glucuronide (CG) were determined. The cDNA of UGT1A1 was introduced into HeLa cells using the lentiviral transfection method. The modified cells were functional in generation of the glucuronide from chrysin. Ko143 at 10-20 ?M (a dual inhibitor of BCRP and UGT1A1) caused a marked decrease (51.3%-59.7%, P < 0.01) in the excretion rate and efflux clearance of CG. Likewise, MK-571 at 5-20 ?M (an inhibitor of MRPs but an activator of UGT1A1) resulted in a significant reduction in the excretion rate (18.2%-64.0%, P < 0.01) and efflux clearance (37.0%-90.2%, P < 0.001). By contrast, dipyridamole and leukotriene C4 showed no inhibitory effects on CG excretion. The chemical inhibition indicated that excretion of CG was contributed by the MRP family transporters, whereas the role of BCRP was unclear. Furthermore, short hairpin RNA-mediated silencing of a target transporter led to a marked reduction in the excretion rate of CG (38.6% for BCRP, 39.3% for MRP1, 36.4% for MRP3, and 28.7% for MRP4; P < 0.01). Transporter silencing also led to substantial decreases in the efflux clearance (44.7% for BCRP, 60.4% for MRP1, 36.7% for MRP3, and 28.7% for MRP4; P < 0.01). The gene silencing results suggested that BCRP, MRP1, MRP3, and MRP4 were significant contributors to excretion of CG. PMID:25595598

Quan, Enxi; Wang, Huailing; Dong, Dong; Zhang, Xingwang; Wu, Baojian

2015-04-01

86

Simultaneous determination of esculetin, quercetin-3-O-?-D-glucuronide, quercetin-3-O-? -D-glucuronopyranside methyl ester and quercetin in effective part of Polygonum Perfoliatum L. using high performace liquid chromatography  

PubMed Central

Objective: In the present study, a high performance liquid chromatography (HPLC) coupled with photodiode array detection was developed for simultaneous quantitation of esculetin, quercetin-3-O-?-D-glucuronide, quercetin-3-O-?-D- glucuronopyranoside methyl ester and quercetin in Polygonum perfoliatum L. Materials and Methods: The chromatographic separations were performed on a reversed-phase C18 column using a mobile phase composed of acetonitrile -0.5% aqueous acetic acid with gradient elution. The calibration curves for the analytes demonstrated good linearities within the investigated ranges. The satisfactory intra- and inter-day precision, repeatability and stability of the developed analytical method were shown in the method validation procedure. The recoveries of the established method ranged from 95.76 to 102.10% for all the analytes. Results: This proposed method was successfully applied for simultaneous quantification of the four compounds in effective part of Polygonum perfoliatum L. from different regions. Hierarchical clustering analysis (HCA) and principal components analysis (PCA) were performed to characterize and classify the samples based on the contents of the four compounds in Polygonum perfoliatum L. Conclusion: The established HPLC method combined with chemometric approaches was proven to be useful and efficient for quality control of Polygonum perfoliatum L. PMID:25210326

Fan, Dongsheng; Zhao, Yang; Zhou, Xin; Gong, Xiaojian; Zhao, Chao

2014-01-01

87

Detection of pentachlorophenol and its glucuronide and sulfate conjugates in fish bile and exposure water  

SciTech Connect

The glucuronide and sulfate conjugates of pentachlorophenol (PCP) that were present in the bile and exposure water of goldfish (Carassius auratus) were used to develop methodology to quantify PCP and its metabolites. Reverse phase HPLC with radioactivity detection separated PCP and its metabolites, and was used to verify a method of quantification that used differential extraction and scintillation counting. Extractions of aqueous phase at pH 2 or 8, with butanol, ethyl acetate, or ether indicated that ether at pH 8 best separated PCP from its metabolites. The sulfate conjugate of PCP was the major metabolite produced when goldfish were exposed to 125 micrograms UC-PCP/l. It was present primarily in the exposure water, but also appeared in the bile.

Stehly, G.R.; Hayton, W.L.

1988-08-01

88

Experimental Determination of Densities and Isobaric Vapor-Liquid Equilibria of Methyl Acetate and Ethyl Acetate with Alcohols (C3 and C4) at 0.3 MPa  

NASA Astrophysics Data System (ADS)

The densities and excess volumes were determined at 298.15 K for the methyl acetate + 1-propanol, methyl acetate + 1-butanol, and ethyl acetate + 1-butanol mixtures. The vapor-liquid equilibria data at 0.3 MPa for these binary systems were obtained using a stainless steel equilibrium still. The activity coefficients were obtained from the experimental data using the Hayden and O’Connell method and the Yen and Woods equation. The binary systems in this study showed positive deviations from ideality. The experimental VLE data were verified with the point-to-point test of van Ness using the Barker routine and the Fredenslund criterion. The different versions of the UNIFAC and the ASOG group contribution models were applied.

Susial, Pedro; Estupiñan, Esteban J.; Castillo, Victor D.; Rodríguez-Henríquez, José J.; Apolinario, José C.

2013-10-01

89

Determining the degradation efficiency and mechanisms of ethyl violet using HPLC-PDA-ESI-MS and GC-MS  

PubMed Central

Background The discharge of wastewater that contains high concentrations of reactive dyes is a well-known problem associated with dyestuff activities. In recent years, semiconductor photocatalysis has become more and more attractive and important since it has a great potential to contribute to such environmental problems. One of the most important aspects of environmental photocatalysis is in the selection of semiconductor materials like ZnO and TiO2, which are close to being two of the ideal photocatalysts in several respects. For example, they are relatively inexpensive, and they provide photo-generated holes with high oxidizing power due to their wide band gap energy. In this work, nanostructural ZnO film on the Zn foil of the Alkaline-Manganese Dioxide-Zinc Cell was fabricated to degrade EV dye. The major innovation of this paper is to obtain the degradation mechanism of ethyl violet dyes resulting from the HPLC-PDA-ESI-MS analyses. Results The fabrication of ZnO nanostructures on zinc foils with a simple solution-based corrosion strategy and the synthesis, characterization, application, and implication of Zn would be reported in this study. Other objectives of this research are to identify the reaction intermediates and to understand the detailed degradation mechanism of EV dye, as model compound of triphenylmethane dye, with active Zn metal, by HPLC-ESI-MS and GC-MS. Conclusions ZnO nanostructure/Zn-foils had an excellent potential for future applications on the photocatalytic degradation of the organic dye in the environmental remediation. The intermediates of the degradation process were separated and characterized by the HPLC-PDA-ESI-MS and GC-MS, and twenty-six intermediates were characterized in this study. Based on the variation of the amount of intermediates, possible degradation pathways for the decolorization of dyes are also proposed and discussed. PMID:22748361

2012-01-01

90

Ethyl propiolate as a post-column derivatization reagent for thiols: development of a green liquid chromatographic method for the determination of glutathione in vegetables.  

PubMed

The present study reports the development, validation and application of a new green liquid chromatographic method for the determination of glutathione (GSH) in vegetable samples. In this work we introduce-for the first time-ethyl propiolate (EP) as an advantageous post-column derivatization reagent for thiolic compounds. GSH (t(R)=6.60 min) and N-acetylcysteine (NAC, internal standard) (t(R)=11.80 min) were separated efficiently from matrix endogenous compounds by using a 100% aqueous mobile phase (0.1%, v/v CH(3)COOH in 1 mmol L(-1) EDTA, Q(V)=0.5 mL min(-1)) and a Prevail(®) reversed phase column that offers the advantage of stable packing material in aqueous mobile phases. The parameters of the post-column reaction (pH, amount concentration of the reagent, flow rates, length of the reaction coil and temperature) were studied. The linear determination range for GSH was 1-200 ?mol L(-1) and the LOD was 0.1 ?mol L(-1) (S/N=3). Total endogenous GSH was determined in broccoli, potato, asparagus and Brussels sprouts using the standards addition approach. The accuracy was evaluated by both recovery experiments (R=91-110%) and comparison to an o-phthalaldehyde/glycine corroborative post-column derivatization fluorimetric method. PMID:21414445

Zacharis, Constantinos K; Tzanavaras, Paraskevas D; Zotou, Anastasia

2011-03-25

91

The effect of various drugs on the glucuronidation of zidovudine (azidothymidine; AZT) by human liver microsomes.  

PubMed Central

1. Zidovudine (3'-azido-3'-deoxythymidine; AZT) is the drug of proven efficacy available for the treatment of patients with AIDS or ARC. It is eliminated mainly by hepatic glucuronidation. Therefore, interference with this metabolic pathway may lead to enhancement of AZT effect or to increased toxicity of the drug. We have examined the effect of a number of drugs which themselves undergo glucuronidation on AZT conjugation by human liver microsomes in vitro. 2. AZT glucuronidation followed Michaelis-Menten kinetics. The apparent Km and Vmax values (mean +/- s.d., n = 5), were 2.60 +/- 0.52 mM and 68.0 +/- 23.4 nmol h-1 mg-1, respectively, as determined from Eadie-Hofstee plots. 3. Dideoxyinosine, sulphanilamide and paracetamol were essentially non-inhibitory at concentrations up to 10 mM (4 times the concentration of AZT in the incubation). The most marked inhibitory effects were seen with indomethacin, naproxen, chloramphenicol, probenecid and ethinyloestradiol, with enzyme activity decreased by 97.7, 94.9, 88.7, 83.4% and 79.0%, respectively, at a concentration of 10 mM. Other compounds producing some inhibition of AZT conjugation were oxazepam, salicylic acid and acetylsalicylic acid. 4. Further studies are necessary to characterise the inhibition observed but the method described enables a screen of potentially important drug interactions to be carried out. PMID:1909542

Sim, S M; Back, D J; Breckenridge, A M

1991-01-01

92

Pharmacokinetics of mycophenolic acid and its phenolic-glucuronide and ACYl glucuronide metabolites in stable thoracic transplant recipients.  

PubMed

Mycophenolate mofetil is an immunosuppressant commonly used in solid organ transplantation. Its active metabolite, mycophenolic acid (MPA), is metabolized to the inactive 7-O-mycophenolic acid glucuronide (MPAG) and the active acyl glucuronide (AcMPAG). Most pharmacokinetic (PK) studies have been focused on MPA, but not its metabolites, in kidney transplant recipients. Pharmacokinetic studies of MPA and its metabolites in thoracic transplant recipients are scarce. Because neither the heart nor lung is involved in MPA metabolism or excretion, the thoracic transplant population may exhibit unique PKs. This open-label study aimed to characterize and compare PKs of MPA and its metabolites in stable lung or heart transplant recipients. Fifty thoracic (27 lung, 23 heart) transplant recipients were recruited. Subjects were also taking cyclosporine (11 lung, 14 heart) or tacrolimus (16 lung, nine heart), and prednisone (27 lung, one heart). Blood samples were obtained at 0, 20, 40, 60, and 90 minutes and 2, 4, 6, 8, 10, and 12 hours postdose. Plasma was used for drug level analysis (MPA, MPAG, and AcMPAG) by a high-performance liquid chromatography-ultraviolet detection method; in a subset of subjects, free MPA concentrations were also determined. Conventional PK parameters (dose-normalized) were determined by noncompartmental methods. There was wide interpatient variability of MPA, MPAG, and AcMPAG PKs with coefficients of variation exceeding 70% for most PK parameters measured. Other findings (P < 0.05) included: lower MPA area under the curve, maximum concentration, and minimum concentration; higher apparent clearance and MPAG/MPA metabolic ratio in the lung versus heart transplant group; lower MPA area under the curve and minimum concentration, and higher apparent clearance and MPAG/MPA metabolic ratio in lung transplant recipients concurrently taking cyclosporine versus tacrolimus; and lower minimum concentration in heart transplant recipients taking cyclosporine versus tacrolimus. Despite large interpatient variability in the PKs of MPA, MPAG, and AcMPAG among thoracic transplant recipients, there appear to be significant differences between lung and heart patients, which warrant further study. PMID:18520599

Ting, Lillian S L; Partovi, Nilufar; Levy, Robert D; Riggs, K Wayne; Ensom, Mary H H

2008-06-01

93

Low level determinations of methyl methanesulfonate and ethyl methanesulfonate impurities in Lopinavir and Ritonavir Active pharmaceutical ingredients by LC/MS/MS using electrospray ionization.  

PubMed

Methyl methanesulfonate (MMS) and ethyl methanesulfonate (EMS) have been highlighted as potential genotoxic impurities (PGIs). A sensitive LC/MS/MS method is developed and validated for the determination of MMS and EMS impurities in both Lopinavir and Ritonavir Active pharmaceutical ingredient. Method utilizes, Atlantis T3 column with electrospray ionization in multiple reactions monitoring (MRM) mode for quantitation of impurities. The proposed method is specific, linear, accurate and precise. The calibration curves show good linearity over the concentration range of 0.01-0.23 ?g/mL for MMS and 0.005-0.23 ?g/mL for EMS. The correlation coefficient obtained is >0.99 in each case. Method has very low limit of detection (LOD) and quantification (LOQ). LOD and LOQ of MMS and EMS are as low as ?0.002 ?g/mL and ?0.01 ?g/mL respectively. Method has accuracy within 80-120% for both the analytes. This method is a good quality control tool for quantitation of MMS and EMS impurities at very low levels in Lopinavir and Ritonavir. PMID:21353429

Kakadiya, P R; Reddy, B Pratapa; Singh, V; Ganguly, S; Chandrashekhar, T G; Singh, D K

2011-05-15

94

Simultaneous Quantification of Buprenorphine, Norbuprenorphine, Buprenorphine-Glucuronide and Norbuprenorphine-Glucuronide in Human Umbilical Cord by Liquid Chromatography Tandem Mass Spectrometry  

PubMed Central

A LCMS method was developed and validated for the simultaneous determination of buprenorphine (BUP), norbuprenorphine (NBUP), buprenorphine glucuronide (BUP-Gluc) and norbuprenorphine glucuronide (NBUP-Gluc) in human umbilical cord. Quantification was achieved by selected ion monitoring of precursor ions m/z 468.4 for BUP; 414.3 for NBUP; 644.4 for BUP-Gluc and 590 for NBUP-Gluc. BUP and NBUP were identified by MS2, with m/z 396, 414 and 426 for BUP, and m/z 340, 364 and 382 for NBUP. Glucuronide conjugates were identified by MS3 with m/z 396 and 414 for BUP-Gluc and m/z 340 and 382 for NBUP-Gluc. The assay was linear 1–50 ng/g. Intra, inter-day and total assay imprecision (%RSD) were <14.5%, and analytical recovery ranged from 94.1% to 112.3% for all analytes. Extraction efficiencies were >66.3%, and process efficiency >73.4%. Matrix effect ranged, in absolute value, from 3.7% to 27.4% (CV<21.8%, n=8). The method was selective with no endogenous or exogenous interferences from 41 compounds evaluated. Sensitivity was high with limits of detection of 0.8 ng/g. In order to prove method applicability, an authentic umbilical cord obtained from an opioid-dependent pregnant woman receiving BUP pharmacotherapy was analyzed. Interestingly, BUP was not detected but concentrations of the other metabolites were NBUP-Gluc 13.4 ng/g, BUP-Gluc 3.5 ng/g and NBUP 1.2 ng/g. PMID:19406593

Concheiro, Marta; Shakleya, Diaa M.; Huestis, Marilyn A.

2009-01-01

95

Hepatocyte cotransport of taurocholate and bilirubin glucuronides: Role of microtubules  

SciTech Connect

Modulation of bile pigment excretion by bile salts has been attributed to modification of canalicular membrane transport or a physical interaction in bile. Based on the observation that a microtubule-dependent pathway is involved in the hepatocellular transport of bile salts, the authors investigated the possibility that bilirubin glucuronides are associated with bile salts during intracellular transport. Experiments were conducted in intact rats (basal) or after overnight biliary diversion and intravenous reinfusion of taurocholate (depleted/reinfused). All rats were pretreated with intravenous low-dose colchicine or its inactive isomer lumicolchicine. Biliary excretion of radiolabeled bilirubin glucuronides derived from tracer ({sup 14}C)bilirubin-({sup 3}H)bilirubin monoglucuronide (coinjected iv) was unchanged in basal rats but was consistently delayed in depleted/reinfused rats. This was accompanied by a significant shift toward bilirubin diglucuronide formation from both substrates. In basal Gunn rats, with deficient bilirubin glucuronidation, biliary excretion of intravenous ({sup 14}C)bilirubin monoglucuronide-({sup 3}H)bilirubin diglucuronide was unaffected by colchicine but was retarded in depleted/reinfused Gunn rats. Colchicine had no effect on the rate of bilirubin glucuronidation in vitro in rat liver microsomes. They conclude that a portion of the bilirubin glucuronides generated endogenously in hepatocytes or taken up directly from plasma may be cotransported with bile salts to the bile canalicular membrane via a microtubule-dependent mechanism.

Crawford, J.M.; Gollan, J.L. (Harvard Medical School, Boston, MA (USA))

1988-07-01

96

Non-steroidal anti-inflammatory drugs interact with testosterone glucuronidation  

Microsoft Academic Search

Testosterone and epitestosterone are secreted mainly as glucuronide metabolites and the urinary ratio of testosterone glucuronide to epitestosterone glucuronide, often called T\\/E, serves as a marker for possible anabolic steroids abuse by athletes. UDP-glucuronosyltransferase (UGT) 2B17 is the most important catalyst of testosterone glucuronidation. The T\\/E might be affected by drugs that interact with UGT2B17, or other enzymes that contribute

Taina Sten; Moshe Finel; Birgitta Ask; Anders Rane; Lena Ekström

2009-01-01

97

Microvascular protective activity of flavonoid glucuronides fraction from Tulipa gesneriana.  

PubMed

A mixture of flavonoid glucuronides, consisting of 7-O-glucuronides of kaempferol and quercetin 3-O-rutinosides, 3-O-gentiobiosides and 3-O-glucosides, was isolated from the perianths of Tulipa gesneriana L. var. 'Paradae'. It showed protective activity against the increased (both chloroform and histamine) skin vascular permeability in rabbits. The protective effect, measured as the reduction in leakage of Evans blue, was 59.8% after peritoneal treatment at a dose of 25 mg/kg, while that of troxerutin was 45.5%. PMID:10190195

Budzianowski, J; Korzeniowska, K; Chmara, E; Mrozikiewicz, A

1999-03-01

98

Multiple headspace solid-phase microextraction after matrix modification for avoiding matrix effect in the determination of ethyl carbamate in bread.  

PubMed

This study presents the potential of multiple headspace solid-phase microextraction (multiple HS-SPME) for the quantification of analytes in solid samples. Multiple HS-SPME shares the same advantages as SPME. It also enables a complete recovery of the target compound and therefore the matrix effect, which commonly appears in SPME-based analysis, is avoided. A method based on multiple HS-SPME for the determination of the toxic contaminant ethyl carbamate (EC) in bread samples has been developed and validated, using gas chromatography with flame ionization detector. A novel polyethylene glycol/hydroxy-terminated silicone oil fiber was prepared for the first time and subsequently used instead of commercial ones because of its high extraction ability and good operational stability. An important problem still remained in multiple HS-SPME of EC in fresh bread samples. The adsorption of EC by water in the samples caused low transport of analyte to the headspace, which made multiple HS-SPME invalidated. Mixing with anhydrous sodium sulphate, the sensitivity of the method was improved and the problem was solved. The proposed method showed satisfactory linearity (0.15-1500 ?g g(-1)), precision (1.6%, n=5) and limit of detection (0.041 ?g g(-1)). Good recoveries, from 92.5 to 103.4%, were observed at three spiking levels. The method was applied to 14 bread samples. The multiple HS-SPME technique offers several advantages including reducing the manipulation time and cost, and avoiding analyte losses, especially in the analysis of a large number of samples in different matrices. PMID:22123114

Ye, Chang-Wen; Zhang, Xue-Na; Gao, Yuan-Li; Wang, Yu-Long; Pan, Si-Yi; Li, Xiu-Juan

2012-01-13

99

Disruption of thyroid hormone homeostasis in Ugt1a-deficient Gunn rats by microsomal enzyme inducers is not due to enhanced thyroxine glucuronidation  

SciTech Connect

Microsomal enzyme inducers (MEI) that increase UDP-glucuronosyltransferases (UGTs) are thought to increase glucuronidation of thyroxine (T{sub 4}), thus reducing serum T{sub 4}, and subsequently increasing thyroid stimulating hormone (TSH). Ugt1a1 and Ugt1a6 mediate T{sub 4} glucuronidation. Therefore, this experiment determined the involvement of Ugt1a enzymes in increased T{sub 4} glucuronidation, decreased serum T{sub 4}, and increased TSH after MEI treatment. Male Wistar and Ugt1a-deficient Wistar (Gunn) rats were fed a control diet or diet containing pregnenolone-16{alpha}-carbonitrile (PCN; 800 ppm), 3-methylcholanthrene (3-MC; 200 ppm), or Aroclor 1254 (PCB; 100 ppm) for 7 days. Serum T{sub 4}, triiodothyronine (T{sub 3}), and TSH concentrations, hepatic T{sub 4}/T{sub 3} glucuronidation, and thyroid histology and follicular cell proliferation were investigated. PCN, 3-MC, and PCB treatments decreased serum T{sub 4}, whereas serum T{sub 3} was maintained in both Gunn and Wistar rats (except for PCB treatment). TSH was increased in Wistar and Gunn rats after PCN (130 and 277%) or PCB treatment (72 and 60%). T{sub 4} glucuronidation in Wistar rats was increased after PCN (298%), 3-MC (85%), and PCB (450%), but was extremely low in Gunn rats, and unchanged after MEI. T{sub 3} glucuronidation was increased after PCN (121%) or PCB (58%) in Wistar rats, but only PCN increased T{sub 3} glucuronidation in Gunn rats (43%). PCN treatment induced thyroid morphological changes and increased follicular cell proliferation in both strains. These data demonstrate that T{sub 4} glucuronidation cannot be increased in Ugt1a-deficient Gunn rats. Thus, the decrease in serum T{sub 4}, increase in TSH, and increase in thyroid cell proliferation after MEI are not dependent on increased T{sub 4} glucuronidation, and cannot be attributed to Ugt1a enzymes.

Richardson, Terrilyn A.; Klaassen, Curtis D., E-mail: cklaasse@kumc.ed

2010-10-01

100

Resveratrol Is Absorbed in the Small Intestine as Resveratrol Glucuronide  

Microsoft Academic Search

We have studied the absorption and metabolism of resveratrol in the jejunum in an isolated rat small intestine model. Only small amounts of resveratrol were absorbed across the enterocytes of the jejunum and ileum unmetabolised. The major compound detected on the serosal side was the glucuronide conjugate of resveratrol (96.5% ± 4.6 of the amount absorbed) indicating the susceptibility of

Gunter Kuhnle; Jeremy P. E. Spencer; George Chowrimootoo; Hagen Schroeter; Edward S. Debnam; S. Kaila S. Srai; Catherine Rice-Evans; Ulrich Hahn

2000-01-01

101

Fate of glucuronide conjugated estradiol in the environment  

Technology Transfer Automated Retrieval System (TEKTRAN)

The fate and transport of conjugated reproductive hormones, which are polar compared to parent hormones, are little understood. Laboratory bench-scale soil (Hamar; Sandy, mixed, frigid typic Endoaquolls) sorption studies were conducted using [14C] 17ß-estradiol-3-glucuronide for a range of concentra...

102

Determination of the spin-Peierls distortion in N-methyl-N-ethyl-morpholinium ditetracyanoquinodimethanide [MEM(TCNQ)2]: Neutron diffraction study at 6 K  

Microsoft Academic Search

We have carried out a crystallographic study of the spin-Peierls distorted phase (Tc=17.4 K) of N-methyl-N-ethyl-morpholinium ditetracyanoquinodimethanide [MEM(TCNQ)2]. Neutron-diffraction data were collected at 6 K from a deuterated sample. At the transition the unit cell axis along the dimerized TCNQ stack is doubled, hence giving rise to tetramers. Refinement of rigid molecules converged to R=0.162 for 340 super-reflections. The structural

R. J. J. Visser; S. Oostra; C. Vettier; J. Voiron

1983-01-01

103

New spectrofluorimetric methods for determination of melatonin in the presence of N-{2-[1-({3-[2-(acetylamino)ethyl]-5-methoxy-1H-indol-2-yl}methyl)-5-methoxy-1H-indol-3-yl]- ethyl}acetamide: a contaminant in commercial melatonin preparations  

PubMed Central

Background Melatonin (MLT) has many health implications, therefore it is of valuable importance to develop specific analytical methods for determination of MLT in the presence of its main contaminant, N-{2-[1-({3-[2-(acetylamino)ethyl]-5-methoxy-1H-indol-2-yl}methyl)-5-methoxy-1H-indol-3-yl]ethyl}acetamide (10). For development of these analytical methods, compound 10 had to be prepared in an adequate amount. Results Compound 10 was synthesized in six steps starting from 5-methoxyindole-2-carboxylic acid (1). Analytical performance of the proposed spectrofluorimetric methods was statistically validated with respect to linearity, accuracy, precision and specificity. The proposed methods were successfully applied for the assay of MLT in laboratory prepared mixtures containing up to 60 % of compound 10 and in commercial MLT tablets with recoveries not less than 99.00 %. No interference was observed from common pharmaceutical additives and the results were favorably compared with those obtained by a reference method. Conclusions This work describes simple, sensitive, and reliable second derivative spectrofluorimetric method in addition to two multivariate calibration methods, principal component regression (PCR) and partial least square (PLS), for the determination of MLT in the presence of compound 10. PMID:22551394

2012-01-01

104

Glucuronidation of fimasartan, a new angiotensin receptor antagonist, is mainly mediated by UGT1A3.  

PubMed

1. Fimasartan is an angiotensin receptor II antagonist used to treat patients with hypertension. This drug is mainly excreted into bile as either the parent compound or a glucuronide conjugate. In this study, we examined the glucuronidation of fimasartan and characterized the UDP-glucuronosyltransferases (UGTs) responsible for the glucuronidation. 2. Only one type of fimasartan glucuronide was observed after incubation with pooled human liver microsomes (HLMs) and was identified as an N2-glucuronide based on comparison with an authentic standard. 3. Among the 12 UGT isoforms tested, UGT1A1, UGT1A3 and UGT2B7 showed catalytic activity toward fimasartan glucuronidation. The intrinsic clearance (CLint) of UGT1A3 was 68.5- and 21.4-fold higher than that of UGT1A1 and UGT2B7, respectively, and the estimated relative contribution of UGT1A3 in human liver was 94.1%. Both chemical inhibition and correlation studies demonstrated that fimasartan glucuronidation activity in HLMs was significantly related with UGT1A3 activity. Fimasartan glucuronide was identified as a substrate for P-glycoprotein (Pgp) and breast cancer response protein (BCRP). 4. These findings collectively indicate that UGT1A3 is the major UGT isoform responsible for the glucuronidation of fimasartan, and this glucuronide is excreted from hepatocytes via MDR1 and BCRP. PMID:25034008

Jeong, Eun-Sook; Kim, Yang-Weon; Kim, Hyo-Ji; Shin, Ho-Jung; Shin, Jae-Gook; Kim, Kwang Hee; Chi, Yong Ha; Paik, Soo Heui; Kim, Dong-Hyun

2015-01-01

105

Biotransformation of zearalenone and zearalenols to their major glucuronide metabolites reduces estrogenic activity.  

PubMed

Zearalenone (ZEN) is a mycotoxin produced by Fusarium fungi. Once ingested, ZEN may be absorbed and metabolised to ?- and ?-zearalenol (?-ZOL, ?-ZOL), and to a lesser extent ?- and ?-zearalanol (?-ZAL, ?-ZAL). Further biotransformation to glucuronide conjugates also occurs to facilitate the elimination of these toxins from the body. Unlike ZEN and its metabolites, information regarding the estrogenic activity of these glucuronide conjugates in various tissues is lacking. ZEN-14-O-glucuronide, ?-ZOL-14-O-glucuronide, ?-ZOL-7-O-glucuronide, ?-ZOL-14-O-glucuronide and ?-ZOL-16-O-glucuronide, previously obtained as the major products from preparative enzymatic synthesis, were investigated for their potential to cause endocrine disruption through interference with estrogen receptor transcriptional activity. All five glucuronide conjugates showed a very weak agonist response in an estrogen responsive reporter gene assay (RGA), with activity ranging from 0.0001% to 0.01% of that of 17?-estradiol, and also less than that of ZEN, ?-ZOL and ?-ZOL which have previously shown estrogenic potencies of the order 17?-estradiol>?-ZOL>ZEN>?-ZOL. Confirmatory mass spectrometry revealed that any activity observed was likely a result of minor deconjugation of the glucuronide moiety. This study confirms that formation of ZEN and ZOL glucuronides is a detoxification reaction with regard to estrogenicity, serving as a potential host defence mechanism against ZEN-induced estrogenic activity. PMID:25645597

Frizzell, Caroline; Uhlig, Silvio; Miles, Christopher O; Verhaegen, Steven; Elliott, Christopher T; Eriksen, Gunnar S; Sørlie, Morten; Ropstad, Erik; Connolly, Lisa

2015-04-01

106

Ethyl alcohol production  

SciTech Connect

Recent price increases and temporary shortages of petroleum products have caused farmers to search for alternate sources of fuel. The production of ethyl alcohol from grain is described and the processes involved include saccharification, fermentation and distillation. The resulting stillage has potential as a livestock feed.

Hofman, V.; Hauck, D.

1980-11-01

107

DETERMINATION OF KOW VALUES FOR A SERIES OF ARYL GLUCURONIDES  

EPA Science Inventory

An important perameter in toxicokinetic modeling is the octanol/water partition coefficient (Kow). This parameter has often been used to predict the accumulation of contaminants from water to fish (Klamer and Beekman 1995); however, few Kow values are available for modeling the b...

108

Glucuronidation of Psilocin and 4-Hydroxyindole by the Human UDP-Glucuronosyltransferases  

PubMed Central

We have examined the glucuronidation of psilocin, a hallucinogenic indole alkaloid, by the 19 recombinant human UDP-glucuronosyltransferases (UGTs) of subfamilies 1A, 2A, and 2B. The glucuronidation of 4-hydroxyindole, a related indole that lacks the N,N-dimethylaminoethyl side chain, was studied as well. UGT1A10 exhibited the highest psilocin glucuronidation activity, whereas the activities of UGTs 1A9, 1A8, 1A7, and 1A6 were significantly lower. On the other hand, UGT1A6 was by far the most active enzyme mediating 4-hydroxyindole glucuronidation, whereas the activities of UGTs 1A7–1A10 toward 4-hydroxyindole resembled their respective psilocin glucuronidation rates. Psilocin glucuronidation by UGT1A10 followed Michaelis-Menten kinetics in which psilocin is a low-affinity high-turnover substrate (Km = 3.8 mM; Vmax = 2.5 nmol/min/mg). The kinetics of psilocin glucuronidation by UGT1A9 was more complex and may be best described by biphasic kinetics with both intermediate (Km1 = 1.0 mM) and very low affinity components. The glucuronidation of 4-hydroxyindole by UGT1A6 exhibited higher affinity (Km = 178 ?M) and strong substrate inhibition. Experiments with human liver and intestinal microsomes (HLM and HIM, respectively) revealed similar psilocin glucuronidation activity in both samples, but a much higher 4-hydroxyindole glucuronidation rate was found in HLM versus HIM. The expression levels of UGTs 1A6–1A10 in different tissues were studied by quantitative real-time-PCR, and the results, together with the activity assays findings, suggest that whereas psilocin may be subjected to extensive glucuronidation by UGT1A10 in the small intestine, UGT1A9 is likely the main contributor to its glucuronidation once it has been absorbed into the circulation. PMID:20007669

Manevski, Nenad; Kurkela, Mika; Höglund, Camilla; Mauriala, Timo; Court, Michael H.; Yli-Kauhaluoma, Jari

2010-01-01

109

Determination of ultratrace amounts of copper (II) by its catalytic effect on the oxidative coupling reaction of 3-methyl-2-benzothiazolinone hydrazone with N-ethyl-N-(2-hydroxy-3-sulfopropyl)-3,5-dimethoxyaniline.  

PubMed

A spectrophotometric method was developed for the determination of ultratrace amounts of copper(II) based on its catalytic effect on the oxidative coupling reaction of 3-methyl-2-benzothiazolinone hydrazone with N-ethyl-N-(2-hydroxy-3-sulfopropyl)-3,5-dimethoxyaniline to produce an intensely coloured dye (lambda(max) = 525 nm) in the presence of hydrogen peroxide. In this reaction, pyridine acted as an effective activator for the catalysis of copper(II). By measuring the absorbance of the dye, copper(II) can be determined at the 0.002-0.1 ng cm(-3) (3.1 x 10(-11)-1.6 x 10(-9) mol dm(-3) level. The relative standard deviation for ten determinations of 0.06 ng cm(0-3) of copper(II) was 2.6%. The proposed method was successfully applied to the determination of copper(II) in tap water and biological material. PMID:9148646

Ohno, S; Teshima, N; Watanabe, T; Itabashi, H; Nakano, S; Kawashima, T

1996-10-01

110

Stereoselective glucuronidation of ornidazole in humans: predominant contribution of UDP-glucuronosyltransferases 1A9 and 2B7.  

PubMed

Ornidazole [R,S-1-chloro-3-(2-methyl-5-nitro-1H-imidazol-1-yl)propan-2-ol] is a chiral 5-nitroimidazole class antimicrobial agent. This study aimed to investigate the principal metabolic pathway of ornidazole in humans and identify the major enzymes involved. A total of 19 metabolites were identified in human urine collected from patients with hepatobiliary diseases after an intravenous drip infusion of 500 mg of racemic ornidazole. Stereoselective glucuronidation, followed by renal excretion, was the principal metabolic pathway of ornidazole in humans, accounting for 37.3% of the administered dose. Screening assays with 12 available human recombinant UDP-glucuronosyltransferases (UGTs) demonstrated that UGT1A9 was the predominant UGT isoform involved in R-ornidazole glucuronidation, whereas S-ornidazole glucuronidation was almost exclusively catalyzed by UGT2B7. Chemical inhibition study with niflumic acid and flurbiprofen supported these findings. Enzyme kinetic parameters were then determined in human liver microsomes (HLMs), human kidney microsomes (HKMs), UGT1A9, and 2B7. The K(m) values for UGT1A9 (15.6 ± 1.6 mM for R-ornidazole) and 2B7 (3.8 ± 0.9 mM for S-ornidazole) were quite similar to those determined in HLMs and HKMs (20.1 ± 1.4 and 17.7 ± 4.0 mM for R-ornidazole; 6.6 ± 1.3 and 3.2 ± 0.4 mM for S-ornidazole). The in vitro intrinsic clearance (CL(int)) ratios of S- to R-ornidazole were approximately 4.3 in HLMs and 6.5 in HKMs, respectively. The hepatic and renal clearances were estimated based on the well-stirred model. Overall, stereoselective glucuronidation was the principal metabolic pathway of ornidazole in humans. Furthermore, UGT1A9 and 2B7 were the predominant UGT isoforms responsible for R- and S-ornidazole glucuronidation in humans, respectively. PMID:23571427

Du, Jiangbo; You, Tiangeng; Chen, Xiaoyan; Zhong, Dafang

2013-07-01

111

Organochlorines inhibit acetaminophen glucuronidation by redirecting UDP-glucuronic acid towards the D-glucuronate pathway  

SciTech Connect

Industry-derived organochlorines are persistent environmental pollutants that are a continuing health concern. The effects of these compounds on drug metabolism are not well understood. In the current study we present evidence that the inhibition of acetaminophen (APAP) glucuronidation by minute concentrations of organochlorines correlates well with their ability to stimulate the D-glucuronate pathway leading to ascorbate synthesis. A set of 6 arylated organochlorines, including 5 PCB (polychlorinated biphenyl) congeners, were assessed for their effects on APAP glucuronidation in isolated hepatocytes from male Sprague-Dawley rats. The capacity of each organochlorine to inhibit APAP glucuronidation was found to be directly proportional to its capacity to stimulate ascorbate synthesis. PCB153, PCB28 and bis-(4-chlorophenyl sulfone) (BCPS) in increasing order were the most effective organochlorines for inhibiting APAP glucuronidation and stimulating the D-glucuronate pathway. None of the 3 inhibitors of APAP glucuronidation were able to alter the expression of UGT1A6, UGT1A7 and UGT1A8 (the major isoforms responsible for APAP glucuronidation in the rat), however, their efficacy at inhibiting APAP glucuronidation was proportional to their capacity to deplete UDP-glucuronic acid (UDPGA). BCPS-mediated inhibition of APAP glucuronidation in isolated hepatocytes had non-competitive characteristics and was insensitive to the inactivation of cytochrome P450. The effective organochlorines were also able to selectively stimulate the hydrolysis of UDPGA to UDP and glucuronate in isolated microsomes, but could not inhibit APAP glucuronidation in microsomes when UDPGA was in excess. We conclude that organochlorines are able to inhibit APAP glucuronidation in hepatocytes by depleting UDPGA via redirecting UDPGA towards the D-glucuronate pathway. Because the inhibition is non-competitive, low concentrations of these compounds could have long term inhibitory effects on the glucuronidating capacity of hepatocytes.

Chan, Tom S. [Centre Hospitalier de l'Universite de Montreal, 264 Rene Levesque E, Montreal, Quebec, H2X 1P1 (Canada)], E-mail: chatsy@gmail.com; Wilson, John X. [Department of Exercise and Nutritional Sciences, University at Buffalo, Buffalo, New York, 14214 (United States); Selliah, Subajini; Bilodeau, Marc; Zwingmann, Claudia [Centre Hospitalier de l'Universite de Montreal, 264 Rene Levesque E, Montreal, Quebec, H2X 1P1 (Canada); Poon, Raymond [Environmental Health Science and Research Bureau, Health Canada, Ottawa, Ontario, K1A 0K9 (Canada); O'Brien, Peter J. [Faculty of Pharmacy, University of Toronto, Toronto, Ontario, M5S 3M2 (Canada)

2008-11-01

112

Rifampin induces alterations in mycophenolic acid glucuronidation and elimination: Implications for drug exposure in renal allograft recipients  

Microsoft Academic Search

Background: Exposure to mycophenolic acid (MPA) and its main metabolites (MPA 7-O-glucuronide [MPAG] and MPA acyl-glucuronide [AcMPAG]) is characterized by a large interindividual and intraindividual variability, resulting in part from variability in glucuronidation (via uridine diphosphate–glucuronosyltransferase isoforms) and excretion via multidrug resistance-associated protein 2 (MRP2). It can be hypothesized that drugs interfering with glucuronidation and excretion will alter (Ac)MPA(G) exposure.Methods:

Maarten Naesens; Dirk R. J. Kuypers; Frank Streit; Victor W. Armstrong; Michael Oellerich; Kristin Verbeke; Yves Vanrenterghem

2006-01-01

113

Determination of iodine values using 1,3-dibromo-5,5-dimethylhydantoin (DBH) and ethyl acetate as solvent. Analytical methods with DBH in respect to environmental and economical concern, part 18.  

PubMed

Iodine values (iodine numbers) of several fixed oils and lard can be determined in ethyl acetate, an easily biodegredable solvent, instead of chloroform according to PH. EUR. 2002. Iodine monobromide has been replaced by 1,3-dibromo-5,5-dimethylhydantoin (DBH) and potassium iodide (KI) and the reaction time was reduced to 5 min only. However, cod-liver oil and linseed oil require a reaction time of 30 min and a smaller weight of sample. Longer reaction times are also necessary for soya oil and wheat germ oil. Iodine values of linseed oil determined according to method A of PH. EUR. 2002, are dependent on the amount of sample, even in the range prescribed by the pharmacopoeia. PMID:15378849

Hilp, M

2004-08-01

114

Nicotine N-glucuronidation relative to N-oxidation and C-oxidation and UGT2B10 genotype in five ethnic/racial groups.  

PubMed

Nicotine metabolism influences smoking behavior and differences in metabolism probably contribute to ethnic variability in lung cancer risk. We report here on the proportion of nicotine metabolism by cytochrome P450 2A6-catalyzed C-oxidation, UDP-glucuronosyl transferase 2B10 (UGT2B10)-catalyzed N-glucuronidation and flavin monooxygenase 3-catalyzed N-oxidation in five ethnic/racial groups and the role of UGT2B10 genotype on the metabolic patterns observed. Nicotine and its metabolites were quantified in urine from African American (AA, n = 364), Native Hawaiian (NH, n = 311), White (n = 437), Latino (LA, n = 453) and Japanese American (JA, n = 674) smokers. Total nicotine equivalents, the sum of nicotine and six metabolites, and nicotine metabolism phenotypes were calculated. The relationship of UGT2B10 genotype to nicotine metabolic pathways was determined for each group; geometric means were computed and adjusted for age, sex, creatinine, and body mass index. Nicotine metabolism patterns were unique across the groups, C-oxidation was lowest in JA and NH (P < 0.0001), and N-glucuronidation lowest in AA (P < 0.0001). There was no difference in C-oxidation among Whites and AA and LA. Nicotine and cotinine glucuronide ratios were 2- and 3-fold lower in AA compared with Whites. Two UGT variants, a missense mutation (Asp67Tyr, rs61750900) and a splice variant (rs116294140) accounted for 33% of the variation in glucuronidation. In AA, the splice variant accounted for the majority of the reduced nicotine glucuronidation. UGT2B10 variant allele carriers had increased levels of C-oxidation (P = 0.0099). Our data indicate that the relative importance of nicotine metabolic pathways varies by ethnicity, and all pathways should be considered when characterizing the role of nicotine metabolism on smoking behavior and cancer risk. PMID:25233931

Murphy, Sharon E; Park, Sung-Shim L; Thompson, Elizabeth F; Wilkens, Lynne R; Patel, Yesha; Stram, Daniel O; Le Marchand, Loic

2014-11-01

115

Analytical procedure for the determination of Ethyl Lauroyl Arginate (LAE) to assess the kinetics and specific migration from a new antimicrobial active food packaging.  

PubMed

Ethyl Lauroyl Arginate (LAE) is a cationic tensoactive compound, soluble in water, with a wide activity spectrum against moulds and bacteria. LAE has been incorporated as antimicrobial agent into packaging materials for food contact and these materials require to comply with the specific migration criteria. In this paper, one analytical procedure has been developed and optimized for the analysis of LAE in food simulants after the migrations tests. It consists of the formation of an ionic pair between LAE and the inorganic complex Co(SCN)(4)(2-) in aqueous solution, followed by a liquid-liquid extraction in a suitable organic solvent and further UV-Vis absorbance measurement. In order to evaluate possible interferences, the ionic pair has been also analyzed by high performance liquid chromatography with UV-Vis detection. Both procedures provided similar analytical characteristics, with linear ranges from 1.10 to 25.00 mg kg(-1), linearity higher than 0.9886, limits of detection and quantification of 0.33 and 1.10 mg kg(-1), respectively, accuracy better than 1% as relative error and precision better than 3.6% expressed as RSD. Optimization of analytical techniques, thermal and chemical stability of LAE, as well as migration kinetics of LAE from experimental active packaging are reported and discussed. PMID:22938611

Pezo, Davinson; Navascués, Beatriz; Salafranca, Jesús; Nerín, Cristina

2012-10-01

116

Trans-stilbene oxide administration increased hepatic glucuronidation of morphine but decreased biliary excretion of morphine glucuronide in rats  

SciTech Connect

The effect of the inducing agent trans-stilbene oxide (TSO) on the metabolism and biliary excretion of (/sup 14/C)morphine was studied in the isolated in situ perfused rat liver. After administration of morphine by intraportal injection or by the segmented retrograde intrabiliary injection technique, the TSO-treated group showed a marked decrease in the biliary recovery of morphine as its glucuronide conjugate (morphine-3-glucuronide (MG)). However, recovery of MG in the venous outflow of the single pass perfusate was greatly increased. These findings suggested that TSO treatment enhanced the formation of MG from morphine and changed the primary route of hepatic elimination of MG. TSO treatment also decreased the excretion of morphine (as MG) in the bile of anesthetized renal-ligated rats. This decreased biliary function required several days to develop and appeared closely associated with the inductive effect of TSO. After i.v. administration of (/sup 14/C)MG itself, biliary recovery was also markedly decreased in TSO-treated rats. It is postulated that the effect of the TSO treatment led to either a decrease in canalicular transport of MG into bile or an increase in the efficiency of transfer of MG to the blood at the sinusoidal side of the hepatocyte. Regardless of the mechanism, the results indicate the need to study compartmentalization of drug transport and metabolism functions.

Fuhrman-Lane, C.; Fujimoto, J.M.

1982-09-01

117

A rapid and sensitive UPLC-MS/MS method for the simultaneous quantification of serum androsterone glucuronide, etiocholanolone glucuronide, and androstan-3?, 17? diol 17-glucuronide in postmenopausal women.  

PubMed

Quantification of steroidal glucuronide conjugates by the indirect methods of immunoassay and GC-MS/MS may underestimate some conjugates since hydrolysis is needed in sample processing. In the present work, a sensitive and rapid liquid chromatography-tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the simultaneous direct quantification of androsterone glucuronide, etiocholanolone glucuronide, and androstan-3?, 17? diol 17-glucuronide in postmenopausal women's serum. The quantification limits are 0.1ng/mL for 3?-diol-17G and 4ng/mL for both ADT-G and Etio-G, respectively, with an extraction from 200?L serum while the total run time is less than 6min for all three glucuronides. In this method, solid phase extraction is used for sample preparation. The assay has been validated in compliance with EndoCeutics SOPs and FDA guidelines for bioanalytical method development and validation. The recovery of glucuronides in stripped serum is consistent with that in unstripped serum, where the average difference in stripped and unstripped is less than 10%. A linear regression model fits well the standard curves of all three compounds with R?0.99 where the weighting factor is 1/X. Interday accuracy and CV for all levels of QCs are within the range of 15% in both stripped and unstripped serum while all calibration curves are within the range of 6% except for LLOQs, which are within the range of 9%. Other parameters have also been assessed such as selectivity, matrix, lipemic and hemolysis effects as well as stabilities in solution and matrix. Incurred sample reanalysis has been performed with a result of over 93% within 20% of the original values. This reliable, sensitive and fast method is ready for large-scale clinical sample assays. PMID:25701608

Ke, Yuyong; Gonthier, Renaud; Isabelle, Maxim; Bertin, Jonathan; Simard, Jean-Nicolas; Dury, Alain Y; Labrie, Fernand

2015-05-01

118

The UDP-Glucuronosyltransferase (UGT) 1A Polymorphism c.2042C>G (rs8330) Is Associated with Increased Human Liver Acetaminophen Glucuronidation, Increased UGT1A Exon 5a/5b Splice Variant mRNA Ratio, and Decreased Risk of Unintentional Acetaminophen-Induced Acute Liver FailureS?  

PubMed Central

Acetaminophen is cleared primarily by hepatic glucuronidation. Polymorphisms in genes encoding the acetaminophen UDP-glucuronosyltransferase (UGT) enzymes could explain interindividual variability in acetaminophen glucuronidation and variable risk for liver injury after acetaminophen overdose. In this study, human liver bank samples were phenotyped for acetaminophen glucuronidation activity and genotyped for the major acetaminophen-glucuronidating enzymes (UGTs 1A1, 1A6, 1A9, and 2B15). Of these, only three linked single nucleotide polymorphisms (SNPs) located in the shared UGT1A-3?UTR region (rs10929303, rs1042640, rs8330) were associated with acetaminophen glucuronidation activity, with rs8330 consistently showing higher acetaminophen glucuronidation at all the tested concentrations of acetaminophen. Mechanistic studies using luciferase-UGT1A-3?UTR reporters indicated that these SNPs do not alter mRNA stability or translation efficiency. However, there was evidence for allelic imbalance and a gene-dose proportional increase in the amount of exon 5a versus exon 5b containing UGT1A mRNA spliced transcripts in livers with the rs8330 variant allele. Cotransfection studies demonstrated an inhibitory effect of exon 5b containing cDNAs on acetaminophen glucuronidation by UGT1A1 and UGT1A6 cDNAs containing exon 5a. In silico analysis predicted that rs8330 creates an exon splice enhancer site that could favor exon 5a (over exon 5b) utilization during splicing. Finally, the prevalence of rs8330 was significantly lower (P = 0.027, ?2 test) in patients who had acute liver failure from unintentional acetaminophen overdose compared with patients with acute liver failure from other causes or a race- or ethnicity-matched population. Together, these findings suggest that rs8330 is an important determinant of acetaminophen glucuronidation and could affect an individual’s risk for acetaminophen-induced liver injury. PMID:23408116

Freytsis, Marina; Wang, Xueding; Peter, Inga; Guillemette, Chantal; Hazarika, Suwagmani; Duan, Su X.; Greenblatt, David J.; Lee, William M.

2013-01-01

119

DEVELOPMENT OF A CLASS-SELECTIVE ENZYME IMMUNOASSAY FOR URINARY PHENOLIC GLUCURONIDES. (R825433)  

EPA Science Inventory

Class-selective immunoassays for the measurement of glucuronides in human urine can aid evaluation of human exposure to complex mixtures of xenobiotics. Therefore, an enzyme immunoassay (EIA) for the group-selective detection of phenolic ...

120

Glucuronidation of 6 alpha-hydroxy bile acids by human liver microsomes.  

PubMed Central

The glucuronidation of 6-hydroxylated bile acids by human liver microsomes has been studied in vitro; for comparison, several major bile acids lacking a 6-hydroxyl group were also investigated. Glucuronidation rates for 6 alpha-hydroxylated bile acids were 10-20 times higher than those of substrates lacking a hydroxyl group in position 6. The highest rates measured were for hyodeoxy- and hyocholic acids, and kinetic analyses were carried out using these substrates. Rigorous product identification by high-field proton nuclear magnetic resonance and by electron impact mass spectrometry of methyl ester/peracetate derivatives revealed that 6-O-beta-D-glucuronides were the exclusive products formed in these enzymatic reactions. These results, together with literature data, indicate that 6 alpha-hydroxylation followed by 6-O-glucuronidation constitutes an alternative route of excretion of toxic hydrophobic bile acids. PMID:3110212

Radomi?ska-Pyrek, A; Zimniak, P; Irshaid, Y M; Lester, R; Tephly, T R; St Pyrek, J

1987-01-01

121

Studies on steroids. CCXVI. Separation of bile acid 3-glucuronides by high-performance liquid chromatography.  

PubMed

The separation of 3-glucuronides of cholate, chenodeoxycholate, deoxycholate, ursodeoxycholate and lithocholate, and their glyco- and tauro-conjugates, has been carried out by high-performance liquid chromatography on a reversed-phase column. The chromatographic behaviour of bile acid 3-glucuronides was dependent on the type of conjugation. An effect of the pH of the mobile phase on the capacity ratio was observed at higher pH for chenodeoxycholate 3-glucuronide, probably owing to steric interaction of the 7 alpha-hydroxy group with the carboxy group in the glucuronyl moiety. Conversion of the alpha-hydroxy function on the steroid nucleus into an oxo group resulted in a 50% decrease in the capacity ratio. Bile acid 3-glucuronides were efficiently separated on Shodex ODS Pak F-411 using three kinds of ammonium phosphate buffer-acetonitrile systems. PMID:4086635

Goto, J; Suzaki, K; Chikai, T; Nagase, K; Nambara, T

1985-11-27

122

Molecular Structure of Ethyl maltol  

NSDL National Science Digital Library

Ethyl maltol was discovered in the 1970s. It was originally isolated from larch tree bark and is produced through fermentation-organic synthesis. Ethyl maltol occurs naturally in cereal, bread crust, coffee, and cocoa. This substance is also used as a flavor enhancer because it tends to mask bad tasting chemicals, and heightens richness and creaminess. The compound has been employed as a flavor enhancer in wine, chocolate, vanilla, fruit flavored drinks, pastries, candy, tobacco, cosmetics, and medicines.

2002-10-11

123

Analysis of morphine and morphine-3beta-D glucuronide in human urine by capillary zone electrophoresis with minimal sample pretreatment.  

PubMed

The presence of two of the metabolites of heroin, free morphine and morphine 3-beta-D-glucuronide (MO3G) in acidified urine samples was simultaneously determined by capillary zone electrophoresis (CZE). In a run buffer containing 50 mM sodium borate and 250 mM boric acid (pH 8.6), free morphine migrates before a group of neutral compounds (peak N) in urine, which move with the velocity of electro-osmotic flow. In contrast, the glucuronidated form is negatively charged and migrates behind peak N. Both analytes can be precisely identified within their respective analytical window by their migration time with respect to peak N. The on-line multi-wavelengths scanning of the peak permits further confirmation. The detection sensitivity of both analytes was increased three-four fold if the samples were introduced with electro-injection as compared with hydrodynamic injection. Limits of detection (LOD) of free and conjugated morphine using electro-injection were 200 ng/mL and 500 ng/mL, respectively, determined at a 3:1 signal to noise ratio. A dramatic increase of free morphine was observed after acid hydrolysis of the urine concomitantly with the decrease of the glucuronidated form. We conclude that CZE is a rapid, simple, sensitive and useful screening technique for detection of heroin metabolites in the urine. PMID:10375121

Wu, W S; Tsai, J L

1999-05-01

124

Profiling of 19-norandrosterone sulfate and glucuronide in human urine: Implications in athlete's drug testing  

Microsoft Academic Search

19-Norandrosterone (19-NA) as its glucuronide derivative is the target metabolite in anti-doping testing to reveal an abuse of nandrolone or nandrolone prohormone. To provide further evidence of a doping with these steroids, the sulfoconjugate form of 19-norandrosterone in human urine might be monitored as well. In the present study, the profiling of sulfate and glucuronide derivatives of 19-norandrosterone together with

Emmanuel Strahm; Norbert Baume; Patrice Mangin; Martial Saugy; Christiane Ayotte; Christophe Saudan

2009-01-01

125

Glucuronidation in the chimpanzee (Pan troglodytes): studies with acetaminophen, oestradiol and morphine.  

PubMed

The chimpanzee has recently been characterized as a surrogate for oxidative drug metabolism in humans and as a pharmacokinetic model for the selection of drug candidates. In the current study, the glucuronidation of acetaminophen, morphine and oestradiol was evaluated in the chimpanzee to extend the characterization of this important animal model. Following oral administration of acetaminophen (600 mg) to chimpanzees (n=2), pharmacokinetics were comparable with previously reported human values, namely mean oral clearance 0.91 vs. 0.62+/-0.05 l h-1 kg-1, apparent volume of distribution 2.29 vs. 1.65+/-0.25 l kg-1, and half-life 1.86 vs. 1.89+/-7h, for chimpanzee vs. human, respectively. Urinary excretions (percentage of dose) of acetaminophen, acetaminophen glucuronide and acetaminophen sulfate were also similar between chimpanzees and humans, namely 2.3 vs. 5.0, 63.1 vs. 54.7, and 25.0 vs. 32.3%, respectively. Acetaminophen, oestradiol and morphine glucuronide formation kinetics were investigated using chimpanzee (n=2) and pooled human liver microsomes (n=10). V(max) (app) and K(m)(app) (or S(50)(app)) for acetaminophen glucuronide, morphine 3- and 6-glucuronide, and oestradiol 3- and 17-glucuronide formation were comparable in both species. Eadie-Hofstee plots of oestradiol 3-glucuronide formation in chimpanzee microsomes were characteristic of autoactivation kinetics. Western immunoblot analysis of chimpanzee liver microsomes revealed a single immunoreactive band when probed with anti-human UGT1A1, anti-human UGT1A6, and anti-human UGT2B7. Taken collectively, these data demonstrate similar glucuronidation characteristics in chimpanzees and humans. PMID:17162465

Wong, H; Grace, J E; Wright, M R; Browning, M R; Grossman, S J; Bai, S A; Christ, D D

2006-12-01

126

In Vitro Glucuronidation of the Antibacterial Triclocarban and Its Oxidative MetabolitesS?  

PubMed Central

Triclocarban (3,4,4?-trichlorocarbanilide; TCC) is widely used as an antibacterial in bar soaps. During use of these soaps, a significant portion of TCC is absorbed by humans. For the elimination from the body, glucuronidation plays a key role in both biliary and renal clearance. To investigate this metabolic pathway, we performed microsomal incubations of TCC and its hydroxylated metabolites 2?-OH-TCC, 3?-OH-TCC, and 6-OH-TCC. Using a new liquid chromatography-UV-mass spectrometry method, we could show a rapid glucuronidation for all OH-TCCs by the uridine-5?-diphosphate-glucuronosyltransferases (UGT) present in liver microsomes of humans (HLM), cynomolgus monkeys (CLM), rats (RLM), and mice (MLM). Among the tested human UGT isoforms, UGT1A7, UGT1A8, and UGT1A9 showed the highest activity for the conjugation of hydroxylated TCC metabolites followed by UGT1A1, UGT1A3, and UGT1A10. Due to this broad pattern of active UGTs, OH-TCCs can be efficiently glucuronidated in various tissues, as shown for microsomes from human kidney (HKM) and intestine (HIM). The major renal metabolites in humans, TCC-N-glucuronide and TCC-N?-glucuronide, were formed at very low conversion rates (<1%) by microsomal incubations. Low amounts of N-glucuronides were generated by HLM, HIM, and HKM, as well as by MLM and CLM, but not by RLM, according to the observed species specificity of this metabolic pathway. Among the human UGT isoforms, only UGT1A9 had activity for the N-glucuronidation of TCC. These results present an anomaly where in vivo the predominant urinary metabolites of TCC are N and N?-glucuronides, but these compounds are slowly produced in vitro. PMID:21953915

Schebb, N. H.; Franze, B.; Maul, R.; Ranganathan, A.

2012-01-01

127

Control of glucuronidation during hypoxia. Limitation by UDP-glucose pyrophosphorylase.  

PubMed Central

The regulation of glucuronidation during hypoxia was studied in isolated hepatocytes by analysing the dependence of acetaminophen glucuronidation rate on the intracellular concentrations of UTP, glucose 1-phosphate, UDP-glucose and UDP-glucuronic acid. The steady-state concentrations of these metabolites in cells from fed and starved rats were altered by exposure to various hypoxic O2 concentrations and by adding exogenous glucose. Changes in glucuronidation rate under all conditions were explained in terms of the concentrations of the substrates for UDP-glucose pyrophosphorylase, i.e. UTP and glucose 1-phosphate. Steady-state rates for the UDP-glucose pyrophosphorylase reaction, calculated by using published kinetic constants and measured glucose 1-phosphate and UTP concentrations, were in agreement with the measured glucuronidation rates. Thus the UDP-glucose pyrophosphorylase reaction is the key regulatory site for drug glucuronidation during hypoxia. Control at this site indicates that glucuronidation in vivo may be generally depressed in pathological conditions involving hypoxia and energy (calorie) malnutrition. PMID:6331395

Aw, T Y; Jones, D P

1984-01-01

128

Simultaneous determination of GHB and EtG in hair using GCMS/MS.  

PubMed

A gas chromatographic tandem mass spectrometric (GCMS/MS) method for simultaneously determining trace concentrations of gamma-hydroxybutyrate (GHB) and ethyl glucuronide (EtG) in hair has been developed. Multiple reaction monitoring (MRM) was used to detect precursor and product ions of GHB, (233 and 147) and EtG (261 and 143) following anion exchange solid phase extraction and derivatization with N,O-bis[trimethylsilyl]trifluoroacetamide (BSTFA). Deuterated standards of GHB and EtG were used as internal standards. The assay produced excellent linearity (r(2) > 0.99) and sensitivity. The lower limit of quantitation (LLOQ) was 10 pg/mg for EtG assuming a 20 mg hair sample. The method has been used to investigate cases of suspected drug facilitated assault as well as being used to identify heavy alcohol consumption in a group of volunteers. PMID:21500364

Paul, R; Tsanaclis, L; Kingston, R; Berry, A; Guwy, A

2011-04-01

129

Development and validation of a reversed-phase high-performance liquid chromatographic method for the determination of ethyl-3-(N-n-butyl-N-acetyl)aminopropionate in an insect repellent semi-solid formulation.  

PubMed

A reversed-phase high-performance liquid chromatographic method with detection at 220 nm was developed and validated for the determination of ethyl-3-(N-n-butyl-N-acetyl)aminopropionate, IR 3535, in an insect repellent semi-solid product. A Hypersil ODS RP-C18 column (250 x 4.6 mm), 5 microm particle size, was equilibrated with a mobile phase consisted of water-acetonitrile (60:40, v/v). Its flow-rate was 1.0 ml/min. Excipients did not interfere with the determination of IR 3535 (Rs = 8.663). Intra- and inter-day relative standard deviations for samples were not higher than 0.61 and 1.2%, respectively. Mean recovery was found not lower than 98.5% and not higher than 100.3%. The method of external standard was adopted. Calibration curves were linear in the concentration range between 1.0 x 10(-6) and 5.0 x 10(-4) M. Limits of detection and quantitation were 65 and 196 ng/ml, respectively. PMID:11873978

Marselos, S C; Archontaki, H A

2002-02-01

130

Development, validation and comparison of two microextraction techniques for the rapid and sensitive determination of pregabalin in urine and pharmaceutical formulations after ethyl chloroformate derivatization followed by gas chromatography-mass spectrometric analysis.  

PubMed

The present article reports first time the use of solid-phase microextraction (SPME) and dispersive liquid-liquid microextraction (DLLME) to extract pregabalin (PRG) from urine and pharmaceutical formulations followed by GC-MS analysis after ethyl chloroformate (ECF) derivatization. PRG is an antiepileptic and analgesic drug, which is a structural analogue of ?-amino-butyric acid (GABA). It is approved by Food and Drug Administration (FDA) for the treatment of central nervous system (CNS) disorders and neuropathic pain. Initially PRG was derivatized with ECF in the presence of pyridine at room temperature for 30s. Experimental parameters were investigated for derivatization, SPME and DLLME conditions. The limit of detection (LOD) and limit of quantitation (LOQ) were found to be 0.019 ?g/ml and 0.063 ?g/ml for SPME and 0.022 ?g/ml and 0.075 ?g/ml for DLLME respectively. The percentage recovery, in case of SPME was in the range of 83-98% while for DLLME it is in the range of 84-98%. The intra and inter-day precisions were found to be less than 6%. The developed methods after ECF derivatization were found to be simple, fast, efficient and inexpensive. DLLME has several advantages like lesser extraction time and cost effectiveness as compared to SPME. The developed methods may find wide application for the routine determination of PRG in biological as well as in quality control samples of pharmaceutical formulations. PMID:22677651

Mudiam, Mohana Krishna Reddy; Chauhan, Abhishek; Jain, Rajeev; Ch, Ratnasekhar; Fatima, Ghizal; Malhotra, Ekta; Murthy, R C

2012-11-01

131

Residual behavior of quizalofop ethyl on onion (Allium cepa L.).  

PubMed

Quizalofop ethyl, a phenoxy propionate herbicide, is used for postemergence control of annual and perennial grass weeds in broad-leaved crops in India. The experiments were designed to study the dissipation kinetics of quizalofop ethyl on onion for two seasons. A simple, rapid, and sensitive method for estimation of quizalofop ethyl residues in onion and soil was developed and validated. The recoveries of quizalofop ethyl residues from onion and soil at different spiking level range from 84.81 to 92.68 %. The limit of quantification of this method was found to be 0.01 ?g g(-1). The risk assessment through consumption of the onion in comparison to its acceptable daily intake which is an important parameter for the safety of the consumer was also evaluated. Standardized methodology supported by recovery studies was adopted to estimate residues of quizalofop ethyl on onion and soil. The average initial deposits of quizalofop ethyl on onion were observed to be 0.25 and 0.33 mg kg(-1), following single application of the herbicide at 50 g active ingredient (a.i.) ha(-1) during 2009 and 2010, respectively. The half-life values (T (1/2)) of quizalofop ethyl on onion crop were worked out to be 0.85 and 0.79 days, respectively, during 2009 and 2010. At harvest time, the residues of quizalofop ethyl on onion and soil were found to be below the determination limit of 0.01 mg kg(-1) following single application of the herbicide at 50 and 100 g a.i. ha(-1) for both the periods. PMID:22572798

Sahoo, S K; Mandal, Kousik; Singh, Gurmail; Kumar, Rajinder; Chahil, G S; Battu, R S; Singh, Balwinder

2013-02-01

132

Reduction and glucuronidation of naftazone by human and rat liver microsomes.  

PubMed

Reduction and glucuronidation of the vasoprotectant drug, naftazone, by human and rat liver microsomes and by recombinant UDP-glucuronosyltransferases (UGT) stably expressed in V79 cells were studied. The oxo group was first reduced in the presence of NADPH or NADH, and was subsequently readily glucuronidated on the phenolic moiety leading to a 1 beta-O-glucuronide, as revealed from MS and by proton and 13C-NMR. Glucuronide extracted from the urine of rats treated with the drug presented the same structure. In all enzyme systems tested, NADH was the most efficient electron donor, when compared with NADPH. The reaction was strongly inhibited by quercitrin, a specific inhibitor of carbonyl reductase. Attempts to isolate the reduced intermediate were unsuccessful because of its marked instability. In humans, a large interindividual variation for the formation of glucuronide was observed with microsomes of seven different liver samples (3.98 +/- 3.22 nmol/min.mg). In rat, glucuronidation of reduced naftazone was strongly induced (12-fold) by 3-methylcholanthrene and, to a lesser extent (2.6-fold) by phenobarbital, but was not affected by clofibrate. In addition, liver microsomes from Gunn rats, which present a genetic defect in bilirubin and phenol UGTs could not form glucuronide of reduced naftazone. The drug, after addition of NADH, was a substrate of the human liver recombinant UGT1*6 that presents a strict specificity toward planar phenolic substances, but not that of UGT2B4 and UGT2B1 expressed in V79 fibroblasts. The reducing step by the endogenous V79 cellular reductase was rate-limiting. In conclusion, the powerful inducing effect exerted by 3-methylcholanthrene, the lack of glucuronidation in the Gunn rat and the ability of UGT1*6 encoded by the UGT1 gene to glucuronidate reduced naftazone suggest that, in humans and in the rat, the compound is metabolized by a UGT isoform (UGT1*6 and the rat orthologous form) belonging to family 1, with a restricted specificity toward the drug. PMID:8689937

Herber, R; Hercelin, B; Van Cantfort, J; De Graeve, J; Fournel-Gigleux, S; Taguchi, T; Magdalou, J

1995-12-01

133

Oral morphine in cancer patients: in vivo kinetics and in vitro hepatic glucuronidation.  

PubMed Central

The kinetics of morphine and formation of the main metabolite, morphine-3-glucuronide (M3G) after single and intravenous doses of morphine were studied in six cancer patients and compared with the formation rate of M3G in vitro in microsomes isolated from liver biopsies obtained from the same patients at palliative laparotomy. The results showed that high formation rates of M3G in vitro in microsomes isolated from liver biopsies were associated both with high apparent oral clearance values and high M3G/morphine AUC (area under the concentration vs time curve) ratios as measured in vivo in the same patients. In accordance with previous results marked interindividual differences were seen in the kinetics of morphine; the oral bioavailability varied between 30 and 69% and the systemic plasma clearance between 18.6 and 34.0 ml min-1 kg-1. This variation correlated with the variation in morphine metabolism as assessed in vitro. In vivo, a high M3G/morphine AUC ratio predicted a high oral clearance. Hepatic UDP-glucuronyl transferase activity is thus an important determinant of the in vivo kinetics of orally administered morphine. PMID:3994897

Säwe, J; Kager, L; Svensson Eng, J O; Rane, A

1985-01-01

134

Effects of herbal supplements on drug glucuronidation. Review of clinical, animal, and in vitro studies.  

PubMed

The use of herbal supplements has increased steadily over the last decade. Recent surveys show that many people who take herbal supplements also take prescription and nonprescription drugs, increasing the risk for potential herb-drug interactions. While cytochrome P450-mediated herb-drug interactions have been extensively characterized, the effects of herbal extracts and constituents on UDP-glucuronosyl transferase (UGT) enzymes have not been adequately studied. Thus, the purpose of this review is to evaluate current evidence on the glucuronidation of phytochemicals and the potential for UGT-mediated herb-drug interactions with the top-selling herbal supplements in the United States and Europe. IN VITRO and animal studies indicate that cranberry, GINKGO BILOBA, grape seed, green tea, hawthorn, milk thistle, noni, soy, St. John's wort, and valerian are rich in phytochemicals that can modulate UGT enzymes. However, the IN VIVO consequences of these interactions are not well understood. Only three clinical studies have investigated the effects of herbal supplements on drugs cleared primarily through UGT enzymes. Evidence on the potential for commonly used herbal supplements to modulate UGT-mediated drug metabolism is summarized. Moreover, the need for further research to determine the clinical consequences of the described interactions is highlighted. PMID:21049395

Mohamed, Mohamed-Eslam F; Frye, Reginald F

2011-03-01

135

Genetic and environmental factors associated with variation of human xenobiotic glucuronidation and sulfation.  

PubMed Central

Glucuronidation and sulfation are phase 2 metabolic reactions catalyzed by large families of different isoenzymes in man. The textbook view that glucuronidation and sulfation lead to the production of harmless conjugates for simple excretion is not valid. Biologically active and toxic sulfates and glucuronides are produced and leed to adverse drug reactions, including immune hypersensitivity. Considerable variation in xenobiotic conjugation is observed as a result of altered expression of UDP-glucuronosyltransferases (UGTs) and sulfotransferases (STs). Recent cloning and expression of human cDNA encoding UGTs and STs has facilitated characterization of isoform substrate specificity, which has been further validated using specific antibodies and human tissue fractions. The availability of cloned/expressed human enzymes and specific antibodies has enabled the investigation of xenobiotic induction and metabolic disruption leeding to adverse responses. Genetic polymorphisms of glucuronidation and sulfation are known to exist although the characterization and assessment of the importance of these variations are hampered by appropriate ethical studies in men with suitable safe model compounds. Genetic analysis has allowed molecular identification of defects in well-known hyperbilirubinemias. However, full characterization of the specific functional roles of human UGTs and STs requires rigorous kinetic and molecular analyses of the role of each enzyme in vivo through the use of specific antibodies and inhibitors. This will leed to the better prediction of variation of xenobiotic glucuronidation and sulfation in man. PMID:9255555

Burchell, B; Coughtrie, M W

1997-01-01

136

An orphan esterase ABHD10 modulates probenecid acyl glucuronidation in human liver.  

PubMed

Probenecid, a widely used uricosuric agent, is mainly metabolized to probenecid acyl glucuronide (PRAG), which is considered a causal substance of severe allergic or anaphylactoid reactions. PRAG can be hydrolyzed (deglucuronidated) to probenecid. The purpose of this study was to identify enzymes responsible for probenecid acyl glucuronidation and PRAG deglucuronidation in human livers and to examine the effect of deglucuronidation in PRAG formation. In human liver homogenates (HLHs), the intrinsic clearance (CLint) of PRAG deglucuronidation was much greater (497-fold) than that of probenecid acyl glucuronidation. Evaluation of PRAG formation by recombinant UDP-glucuronosyltransferase (UGT) isoforms and an inhibition study using HLHs as an enzyme source demonstrated that multiple UGT isoforms, including UGT1A1, UGT1A9, and UGT2B7, catalyzed probenecid acyl glucuronidation. We found that recombinant ?/? hydrolase domain containing 10 (ABHD10) substantially catalyzed PRAG deglucuronidation activity, whereas carboxylesterases did not. Similar inhibitory patterns by chemicals between HLHs and recombinant ABHD10 supported the major contribution of ABHD10 to PRAG deglucuronidation in human liver. Interestingly, it was demonstrated that the CLint value of probenecid acyl glucuronidation in HLHs was increased by 1.7-fold in the presence of phenylmethylsulfonyl fluoride, which potently inhibited ABHD10 activity. In conclusion, we found that PRAG deglucuronidation catalyzed by ABHD10 suppressively regulates PRAG formation via multiple UGT enzymes in human liver. The balance of activities by these enzymes is important for the formation of PRAG, which may be associated with the adverse reactions observed after probenecid administration. PMID:25217485

Ito, Yusuke; Fukami, Tatsuki; Yokoi, Tsuyoshi; Nakajima, Miki

2014-12-01

137

Altered morphine glucuronide and bile acid disposition in patients with nonalcoholic steatohepatitis.  

PubMed

The functional impact of altered drug transport protein expression on the systemic pharmacokinetics of morphine, hepatically derived morphine glucuronide (morphine-3- and morphine-6-glucuronide), and fasting bile acids was evaluated in patients with biopsy-confirmed nonalcoholic steatohepatitis (NASH) compared to healthy subjects. The maximum concentration (Cmax ) and area under the concentration-time curve (AUC0-last ) of morphine glucuronide in serum were increased in NASH patients (343 vs. 225 nM and 58.8 vs. 37.2 µM*min, respectively; P???0.005); morphine pharmacokinetics did not differ between groups. Linear regression analyses detected an association of NASH severity with increased morphine glucuronide Cmax and AUC0-last (P < 0.001). Fasting serum glycocholate, taurocholate, and total bile acid concentrations were associated with NASH severity (P < 0.006). Increased hepatic basolateral efflux of morphine glucuronide and bile acids is consistent with altered hepatic transport protein expression in patients with NASH and may partially explain differences in efficacy and/or toxicity of some highly transported anionic drugs/metabolites in this patient population. PMID:25669174

Ferslew, B C; Johnston, C K; Tsakalozou, E; Bridges, A S; Paine, M F; Jia, W; Stewart, P W; Barritt, A S; Brouwer, Klr

2015-04-01

138

Determination of fenoldopam (SK&F 82526) and its metabolites in human plasma and urine by high-performance liquid chromatography with electrochemical detection.  

PubMed

Fenoldopam [6-chloro-2,3,4,5-tetrahydro-1-(4-hydroxyphenyl)-1H-3-benzazepine-7,8-di ol] is a potent renal vasodilator that is currently undergoing Phase II clinical trials. Quantitative analytical methods, based on high-performance liquid chromatography with electrochemical detection (HPLC-ED) after ethyl acetate extraction from plasma or urine were developed for the determination of fenoldopam and its identified metabolites in biological media. The lower limit of quantitation for fenoldopam in plasma was 50 pg/ml. In assays for fenoldopam glucuronide(s) and fenoldopam conjugates, urine was treated with beta-glucuronidase and Glusulase, respectively, and the liberated fenoldopam was quantified by HPLC-ED. A novel assay by dual-electrode (in series) HPLC-ED was developed for the 8-sulfate of fenoldopam. In this method, the 8-sulfate was oxidized to the o-quinone at the first electrode and quantitated at the second electrode after reduction to the catechol. A similar dual-electrode HPLC-ED method was used for 7- and 8-O-methyl fenoldopam. Conjugates of the O-methyl metabolites were determined by HPLC-ED after hydrolysis to O-methyl fenoldopam. These methods have been used to study the kinetics and metabolism of fenoldopam in healthy volunteers. The methods are specific, sensitive, reproducible, and linear over a wide range of concentrations. Precision of the analyses, expressed as coefficients of variation, were less than 10% for all analyses. PMID:6152270

Boppana, V K; Heineman, F C; Lynn, R K; Randolph, W C; Ziemniak, J A

1984-12-28

139

21 CFR 184.1295 - Ethyl formate.  

Code of Federal Regulations, 2011 CFR

...of ethyl acetate and formic acid in the presence of concentrated sulfuric acid. Ethyl formate occurs naturally in some plant oils, fruits, and juices but does not occur naturally in the animal kingdom. (b) The ingredient meets the...

2011-04-01

140

21 CFR 184.1295 - Ethyl formate.  

Code of Federal Regulations, 2010 CFR

...of ethyl acetate and formic acid in the presence of concentrated sulfuric acid. Ethyl formate occurs naturally in some plant oils, fruits, and juices but does not occur naturally in the animal kingdom. (b) The ingredient meets the...

2010-04-01

141

21 CFR 184.1295 - Ethyl formate.  

Code of Federal Regulations, 2012 CFR

...of ethyl acetate and formic acid in the presence of concentrated sulfuric acid. Ethyl formate occurs naturally in some plant oils, fruits, and juices but does not occur naturally in the animal kingdom. (b) The ingredient meets the...

2012-04-01

142

Inhibition of glucuronidation by an acyl-CoA-mediated indirect mechanism.  

PubMed

The mechanism of the inhibition of glucuronidation by long-chain fatty acyl-CoAs was studied in rat liver microsomal membranes and in isolated hepatocytes. Palmitoyl- and oleoyl-CoA did not affect p-nitrophenol UDP-glucuronosyltransferase activity in native microsomes but were inhibitory in permeabilised vesicles. The extent of inhibition was dependent on the effectiveness of permeabilisation and was constant in time in fully permeabilised microsomes. Fatty acyl-CoAs mobilised calcium from calcium-loaded microsomes. Elevation of the intracellular acyl-CoA level by the addition of palmitate or oleate inhibited the glucuronidation of p-nitrophenol in isolated hepatocytes. This effect could be abolished by emptying the intracellular calcium stores. Therefore, it is concluded that fatty acyl-CoAs inhibit glucuronidation indirectly, presumably via calcium mobilisation. PMID:8831732

Csala, M; Bánhegyi, G; Kardon, T; Fulceri, R; Gamberucci, A; Giunti, R; Benedetti, A; Mandl, J

1996-10-11

143

21 CFR 573.420 - Ethyl cellulose.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2010-04-01 false Ethyl cellulose. 573.420 Section 573.420 Food and...Food Additive Listing § 573.420 Ethyl cellulose. The food additive ethyl cellulose may be safely used in animal feed in...

2010-04-01

144

21 CFR 573.420 - Ethyl cellulose.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Ethyl cellulose. 573.420 Section 573.420 Food and...Food Additive Listing § 573.420 Ethyl cellulose. The food additive ethyl cellulose may be safely used in animal feed in...

2011-04-01

145

21 CFR 172.868 - Ethyl cellulose.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Ethyl cellulose. 172.868 Section 172.868 Food and...Multipurpose Additives § 172.868 Ethyl cellulose. The food additive ethyl cellulose may be safely used in food in accordance...

2011-04-01

146

21 CFR 172.868 - Ethyl cellulose.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2009-04-01 true Ethyl cellulose. 172.868 Section 172.868 Food and...Multipurpose Additives § 172.868 Ethyl cellulose. The food additive ethyl cellulose may be safely used in food in accordance...

2010-04-01

147

A Humanized UGT1 Mouse Model Expressing the UGT1A1*28 Allele for Assessing Drug Clearance by UGT1A1-Dependent Glucuronidation  

PubMed Central

Humanized mice that express the human UDP-glucuronosyltransferase (UGT) 1 locus have been developed in a Ugt1-null background as a model to improve predictions of human UGT1A-dependent drug clearance. Enzyme kinetic parameters (Km and Vmax) and pharmacokinetic properties of three probe drugs were compared using wild-type and humanized UGT1 mice that express the Gilbert’s UGT1A1*28 allele [Tg(UGT1A1*28) Ugt1(?/?) mice]. The well characterized substrate for UGT1A1, 7-ethyl-10-hydroxy-camptothecin (SN-38), showed the greatest difference in parent drug exposure (?3-fold increase) and clearance (?3-fold decrease) in Tg(UGT1A1*28) Ugt1(?/?) mice after intravenous administration compared with wild-type and phenobarbital-treated animals. In contrast, the clearance of the UGT2B7 substrate (?)-17-allyl-4, 5?-epoxy-3, 14-dihydroxymorphinan-6-one (naloxone) was not altered in Tg(UGT1A1*28) Ugt1(?/?) mice. In addition, pharmacokinetic parameters with 1-(4-fluorophenyl)3(R)-[3-(4-fluorophenyl)-3(S)-hydroxypropyl]-4(S)-(4-hydroxyphenyl)-2-azetidinone (ezetimibe, Zetia; Merck & Co., Whitehouse Station, NJ), considered to be a major substrate for UGT1A1, showed small to no dependence on UGT1A1-directed glucuronidation. Enzyme kinetic parameters assessed for SN-38, ezetimibe, and naloxone using liver microsomes prepared from wild-type and Tg(UGT1A1*28) Ugt1(?/?) mice showed patterns consistent with the in vivo pharmacokinetic data. For SN-38 glucuronidation, Vmax decreased 5-fold in Tg(UGT1A1*28) Ugt1(?/?) mouse liver microsomes compared with microsomes prepared from wild-type mice, and decreased 10-fold compared with phenobarbital-treated Tg(UGT1A1*28) Ugt1(?/?) mice. These differences are consistent with SN-38 glucuronidation activities using HLMs isolated from individuals genotyped as UGT1A1*1 or UGT1A1*28. For ezetimibe and naloxone the differences in Vmax were minimal. Thus, Tg(UGT1A1*28) Ugt1(?/?) mice can serve as a pharmacokinetic model to further investigate the effects of UGT1A1 expression on drug metabolism. PMID:20124398

Cai, Hongliang; Nguyen, Nghia; Peterkin, Vincent; Yang, Young-Sun; Hotz, Kathy; Beaton La Placa, Deirdre; Chen, Shujuan; Tukey, Robert H.

2010-01-01

148

Structural modifications at the C-4 position strongly affect the glucuronidation of 6,7-dihydroxycoumarins.  

PubMed

Esculetin (6,7-dihydroxycoumarin) and its C-4 derivatives have multiple pharmacologic activities, but the poor metabolic stability of these catechols has severely restricted their application in the clinic. Glucuronidation plays important roles in catechols elimination, although thus far the effects of structural modifications on the metabolic selectivity and the catalytic efficacy of the human UDP-glucuronosyltransferase (UGT) enzymes remain unclear. This study was aimed at exploring the structure-glucuronidation relationship of esculetin and its C-4 derivatives, including 4-methyl esculetin, 4-phenyl esculetin, and 4-hydroxymethyl esculetin as well as 4-acetic acid esculetin. It was achieved by identifying the main human UGTs responsible for the different reactions and by careful characterization of the reactions kinetics. These catechols, with the exception of 4-acetic acid esculetin, are selectively metabolized to the corresponding 7-O-glucuronides. UGT1A6 and UGT1A9 are the two major UGTs involved in the 7-O-glucuronidation of 4-methyl esculetin and esculetin. UGT1A6 was the major contributor for 7-O-glucuronidation of 4-hydroxymethyl esculetin, and UGT1A9 played a significant role in the 7-O-glucuronidation of 4-phenyl esculetin. The results of the kinetic analyses revealed that the Km values of the compounds, in both UGT1A9 and human liver microsomes, decreased with increasing hydrophobicity of the C-4 substitutions. The outcome of this was that C-4 hydrophobic and hydrophilic groups on 6,7-dihydroxycoumarin exhibited contrasting effects on UGT affinity. All of these findings provide helpful guidance for further structural modification of 6,7-dihydroxycoumarins with improved metabolic stability. PMID:25626951

Xia, Yang-Liu; Ge, Guang-Bo; Wang, Ping; Liang, Si-Cheng; He, Yu-Qi; Ning, Jing; Qian, Xing-Kai; Li, Yan; Yang, Ling

2015-04-01

149

Ethyl levulinate: A potential bio-based diluent for biodiesel which improves cold flow properties  

Technology Transfer Automated Retrieval System (TEKTRAN)

The physical properties of biodiesel from soybean, canola, cottonseed and poultry fat methyl esters were improved with addition of ethyl levulinate with increasing concentration. The effect of adding ethyl levulinate was determined by studying its influence on the acid value, cloud point, pour point...

150

Aldosterone glucuronidation by human liver and kidney microsomes and recombinant UDP-glucuronosyltransferases: Inhibition by NSAIDs  

PubMed Central

AIMS To characterize: i) the kinetics of aldosterone (ALDO) 18?-glucuronidation using human liver and human kidney microsomes and identify the human UGT enzyme(s) responsible for ALDO 18?-glucuronidation and ii) the inhibition of ALDO 18?-glucuronidation by non-selective NSAIDs. METHODS Using HPLC and LC-MS methods, ALDO 18?-glucuronidation was characterized using human liver (n= 6), human kidney microsomes (n= 5) and recombinant human UGT 1A1, 1A3, 1A4, 1A5, 1A6, 1A7, 1A8, 1A9, 1A10, 2B4, 2B7, 2B10, 2B15, 2B17 and 2B28 as the enzyme sources. Inhibition of ALDO 18?-glucuronidation was investigated using alclofenac, cicloprofen, diclofenac, diflunisal, fenoprofen, R- and S-ibuprofen, indomethacin, ketoprofen, ketorolac, meclofenamic acid, mefenamic acid, S-naproxen, pirprofen and tiaprofenic acid. A rank order of inhibition (IC50) was established and the mechanism of inhibition investigated using diclofenac, S-ibuprofen, indomethacin, mefenamic acid and S-naproxen. RESULTS ALDO 18?-glucuronidation by hepatic and renal microsomes exhibited Michaelis-Menten kinetics. Mean (±SD) Km, Vmax and CLint values for HLM and HKCM were 509 ± 137 and 367 ± 170 µm, 1075 ± 429 and 1110 ± 522 pmol min?1 mg?1, and 2.36 ± 1.12 and 3.91 ± 2.35 µl min?1 mg?1, respectively. Of the UGT proteins, only UGT1A10 and UGT2B7 converted ALDO to its 18?-glucuronide. All NSAIDs investigated inhibited ALDO 18?-G formation by HLM, HKCM and UGT2B7. The rank order of inhibition (IC50) of renal and hepatic ALDO 18?-glucuronidation followed the general trend: fenamates > diclofenac > arylpropionates. CONCLUSION A NSAID-ALDO interaction in vivo may result in elevated intra-renal concentrations of ALDO that may contribute to the adverse renal effects of NSAIDs and their effects on antihypertensive drug response. PMID:19740398

Knights, Kathleen M; Winner, Leanne K; Elliot, David J; Bowalgaha, Kushari; Miners, John O

2009-01-01

151

Effect of repeated administrations of heroin, naltrexone, methadone, and alcohol on morphine glucuronidation in the rat  

Microsoft Academic Search

Rationale  Heroin is rapidly metabolized to morphine that in turn is transformed in morphine-3-glucuronide (M3G), an inactive metabolite,\\u000a and morphine-6-glucuronide (M6G), a potent mu-opioid receptor (MOR) agonist. We have found that heroin addicts exhibit higher\\u000a M6G\\/M3G ratios relative to morphine-treated control subjects. We have also shown that heroin-treated rats exhibit measurable\\u000a levels of M6G (which is usually undetectable in this species)

Letizia Antonilli; Emma Petecchia; Daniele Caprioli; Aldo Badiani; Paolo Nencini

2005-01-01

152

Calorimetric Insight into Coupling between Functionalized Primary Alkyl Halide and Vinylic Organocuprate Reagent: Experimental Determination of Reaction Enthalpies in the Synthesis of (R)-Ethyl 3-(tert-butyldimethylsilyloxy)hex-5-enoate - a Key Lactonized Statin Side Chain Precursor.  

PubMed

The first calorimetric study of coupling between organocuprate, derived from Grignard reagent (vinyl magnesium chloride), and primary alkyl halide (e.g. (S)-ethyl 3-(tert-butyldimethylsilyloxy)-4-iodobutanoate) has been conducted. This transformation is paramountly important for efficient preparation of (R)-ethyl 3-(tert-butyldimethylsilyloxy)hex-5-enoate - a key lactonized statin side chain precursor. The results obtained give thorough calorimetric insight into this complex low-temperature synthesis as well as a new understanding of the suggested reductive elimination of the final intermediates in the coupling reaction. Namely, the surprising unexpected spontaneous three-step exothermal event has been observed during controlled progressive heating of the mixture of the final intermediates to the room temperature. This phenomenon confirms that coupling between functionalized primary alkyl halide and vinylic organocuprate reagent is not a simple SN2 substitution reaction. The presented study provides among others the first reported values of reaction enthalpies and corresponding adiabatic temperature rises of reaction mixture for all exothermic events that occurred in the (R)-ethyl 3-(tert-butyldimethylsilyloxy)hex-5-enoate synthesis. The obtained results ensure consequential thermal process safety knowledge which can be incorporated into safe process scale-up as well as design of reactor system with sufficient cooling capacity for industrial production of (R)-ethyl 3-(tert-butyldimethylsilyloxy)hex-5-enoate. Moreover, the results provide a basic guidance for other organocuprate coupling reaction systems. PMID:24061657

Casar, Zdenko; Tramšek, Marko; Goršek, Andreja

2010-03-01

153

Biosynthesis of ethyl butyrate using immobilized lipase: a statistical approach  

Microsoft Academic Search

Response surface methodology was used to determine optimum conditions for the esterification of ethanol and butyric acid to produce a flavor ester using immobilized lipase by Candida antarctica. Various reaction parameters including acid and\\/or alcohol concentration, enzyme concentration, temperature and reaction time affecting the synthesis of ethyl butyrate were investigated. The principal parameters influencing the esterification yield were incubation temperature

José M. Rodriguez-Nogales; Elena Roura; Elizabeth Contreras

2005-01-01

154

Inhibition of the metabolism of ethyl carbamate by acetaldehyde.  

PubMed

Ethyl carbamate is an animal carcinogen when administered in large doses; it is naturally present in minute concentrations in fermented foods and beverages. Previous studies from this laboratory have demonstrated that ethanol, in vivo, inhibits the metabolism of ethyl carbamate in mice, but the enzyme system has not been identified. In an effort to further characterize the enzyme system responsible, the metabolic products of ethanol metabolism were studied to determine whether ethanol or either of its metabolites is inhibitory. Acetaldehyde (400 mg/kg) is a potent inhibitor of ethyl carbamate metabolism for about 2 hr in vitro, but sodium acetate is not. Paraldehyde (250 mg/kg) has a slower onset and longer duration of inhibition, suggesting that its conversion to acetaldehyde produces the inhibitory molecule. Disulfiram (200 mg/kg) has a prolonged inhibitory effect; this effect is enhanced and extended when the disulfiram is combined with acetaldehyde (400 mg/kg). D-Penicillamine, given in a regimen of 1.2 g/kg 0.5 hr before and 0.6 g/kg 1.5 and 3.5 hr after ethyl carbamate, is not inhibitory; however, it abolishes the inhibitory effect of acetaldehyde, presumably from sequestration of acetaldehyde. These studies demonstrate that acetaldehyde is an inhibitor of the metabolism of ethyl carbamate and suggest that acetaldehyde is one, and perhaps the only, molecule responsible for the inhibition seen when ethanol is administered to mice. In vitro incubation studies determined that ethyl carbamate was not metabolized by human plasma. PMID:1976075

Kurata, N; Kemper, R; Hurst, H E; Waddell, W J

1990-01-01

155

UDP-glucuronosyltransferase 1A1 is the principal enzyme responsible for etoposide glucuronidation in human liver and intestinal microsomes: structural characterization of phenolic and alcoholic glucuronides of etoposide and estimation of enzyme kinetics.  

PubMed

Etoposide, an important anticancer agent, undergoes glucuronidation both in vitro and in vivo. In this study, three isomeric glucuronides of etoposide, including one phenolic (EPG) and two alcoholic glucuronides (EAG1 and EAG2), were biosynthesized in vitro with human liver microsomes (HLMs), and identified by liquid chromatography-electrospray ionization-mass spectrometry and confirmed by beta-glucuronidase cleavage. In vitro UDP-glucuronosyltransferase (UGT) reaction screening with 12 recombinant human UGTs demonstrated that etoposide glucuronidation is mainly catalyzed by UGT1A1. Although UGT1A8 and 1A3 also catalyzed the glucuronidation of etoposide, their activities were approximately 10 and 1% of UGT1A1. Enzyme kinetic study indicated that the predominant form of etoposide glucuronide in HLMs and human intestinal microsomes (HIMs) was EPG, whereas EAG1 and EAG2 were the minor metabolites, with approximately an 8 to 10% glucuronidation rate of EPG. For the formation of EPG, the V(max) of HLMs (110 pmol/min/mg protein) was very similar to that of recombinant UGT1A1 (124 pmol/min/mg protein), whereas the V(max) of HIMs (54.4 pmol/min/mg protein) was 2-fold lower than those of HIMs and UGT1A1. The K(m) values of HLMs (530 microM) and HIMs (608 microM) were 2-fold higher than that of UGT1A1 (285 microM). The V(max)/K(m) values for the formation of EPG were 0.21 and 0.09 microl/min/mg protein for HLMs and HIMs, respectively. The data indicated that UGT1A1 is principally responsible for the formation of etoposide glucuronides, mainly in the form of phenolic glucuronide, suggesting that etoposide can be used as a highly selective probe substrate for human UGT1A1 in vitro. PMID:17151191

Wen, Zhiming; Tallman, Melanie N; Ali, Shazia Y; Smith, Philip C

2007-03-01

156

In vitro stereoselective covalent binding of carprofen glucuronides to human serum albumin: characterization of the mechanism.  

PubMed

The reactivity, in terms of covalent binding, of R- and S-carprofen acylglucuronides with human serum albumin (HSA) has been investigated in vitro. The irreversible binding of these metabolites to the HSA 580 mM occurred at pH 7.4 and 37 degrees C instantaneously and stereoselectively in favour of the R-enentiomer glucuronide. The amount of carprofen adducts remained stable with time up to 48 hr, and increased with the glucuronide concentration. It was not modified by addiction of imine-trapping reagents, suggesting that the reaction is not mediated by a Schiff base mechanism. Moreover the extreme rapidity of the covalent binding supports a mechanism of nucleophilic attack. Competition studies with ligands known to bind to different sites of HSA, indicated that carprofen glucuronides interacted mainly with site II. The extent of the binding of R-carprofen glucuronide increased with pH, thus suggesting the participation of an alkaline group in the process. The modification of HSA by amino-acid directed chemicals led to the conclusion that Tyr, Lys or Arg residues in site II were mainly involved. PMID:12712611

Greige-Georges, Hélène; Buronfosse, Thierry; Netter, Patrcik; Magdalou, Jacques; Lapicque, Françoise

2003-01-01

157

Glucuronidation of drugs by hepatic microsomes derived from healthy and cirrhotic human livers.  

PubMed

Pharmacokinetic studies demonstrated that the decrease in drug biotransformation in hepatic failure depends on the metabolic pathways involved. To test whether glucuronidation reactions supported by UDP-glucuronosyltransferases are differentially affected in such conditions, we investigated the in vitro glucuronidation of four selected drugs and xenobiotics (zidovudine, oxazepam, lamotrigine, and umbelliferone) by using microsomes from human healthy and unhealthy (cirrhosis, hepatitis) livers as enzyme sources. Theses substances are glucuronidated by several UDP-glucuronosyltransferase isoforms. Lidocaine N-deethylation activity measured concomitantly was used as a positive control, because the inhibition of this reaction in patients with hepatic diseases is well documented. The metabolic clearances of zidovudine and lidocaine were decreased significantly in liver cirrhosis (0.17 versus 0.37 microliter/min/mg protein and 0.40 versus 2.73 microliter/min/mg protein, respectively) as a consequence of a decrease of their corresponding Vmax of metabolism. By contrast, the metabolic clearances of oxazepam, umbelliferone, and lamotrigine glucuronidation remained unchanged. Previous studies reported that the in vivo oral clearances of zidovudine and lidocaine were decreased by 70% and 60%, respectively, in cirrhotic livers, whereas those of lamotrigine and oxazepam were not affected. Consequently, it is likely that the in vitro metabolic data, which support the in vivo results, therefore could contribute to reasonably predict the level of impairment of hepatic clearance in patients with liver cirrhosis. PMID:10215701

Furlan, V; Demirdjian, S; Bourdon, O; Magdalou, J; Taburet, A M

1999-05-01

158

Age-related increases in F344 rat intestine microsomal quercetin glucuronidation  

Technology Transfer Automated Retrieval System (TEKTRAN)

The objective of this study was to establish the extent age modifies intestinal quercetin glucuronidation capacity. Pooled microsomal fractions of three equidistant small intestine (SI) segments from 4, 12, 18, and 28 mo male F344 rats (n=8/group) were employed to model the enzyme kinetics of UDP-gl...

159

Valproate reduces the glucuronidation of asenapine without affecting asenapine plasma concentrations.  

PubMed

Asenapine is indicated for treatment of schizophrenia in the United States and acute treatment of manic or mixed episodes, as monotherapy (United States and European Union) or adjunct therapy (United States only), associated with bipolar I disorder. It is extensively metabolized; the 2 main metabolites are asenapine N-glucuronide and N-desmethyl-asenapine. The authors investigated the pharmacokinetic interactions between asenapine and valproate in an open-label, randomized, 2-way crossover study. Twenty-four healthy male volunteers received sublingual doses of asenapine 5 mg alone or under steady-state valproate (500 mg bid for 9 days). Blood samples collected until 72 hours postdosing were analyzed for asenapine, N-desmethyl-asenapine, and asenapine N-glucuronide. Compared with asenapine alone, valproate substantially reduced N-glucuronide formation (area under the curve from 0 to infinity [AUC(0-?)] reduced 7.4-fold, maximum concentration [C(max)] reduced 6.6-fold) and moderately reduced N-desmethyl-asenapine formation (AUC(0-?) reduced 30%, C(max) unchanged). Coadministration of valproate did not affect asenapine AUC(0-?) and C(max) (confidence intervals for the ratios of asenapine AUC(0-?) and C(max) were contained within the predefined 0.80-1.25 acceptance range). Low-dose valproate, although almost completely inhibiting glucuronidation of asenapine, did not affect the pharmacokinetics of asenapine itself, the entity primarily responsible for the pharmacologic effects of the drug. PMID:21628604

Gerrits, Mireille G F; de Greef, Rik; Dogterom, Peter; Peeters, Pierre A M

2012-05-01

160

Metabolism of 1'- and 4-hydroxymidazolam by glucuronide conjugation is largely mediated by UDP-glucuronosyltransferases 1A4, 2B4, and 2B7.  

PubMed

Midazolam undergoes oxidative hydroxylation by CYP3A to its metabolites, which are excreted mainly as glucuronidated conjugates into the urine. In this study, we examined the glucuronidation of hydroxymidazolam in human liver microsomes (HLMs) and characterized the UDP-glucuronosyltransferases (UGTs) involved in 1'- and 4-hydroxymidazolam glucuronidation. Among the 12 UGT isoforms tested, the O- and N-glucuronidation of 1'-hydroxymidazolam was mediated by UGT2B4/2B7 and 1A4, respectively. In contrast, the glucuronidation of 4-hydroxymidazolam was mediated by UGT1A4. Consistent with these observations, the UGT1A4 inhibitor hecogenin and the UGT2B7 substrate diclofenac potently inhibited the N- and O-glucuronidation of 1'-hydroxymidazolam in HLMs, respectively. A correlation analysis of UGT enzymatic activity and the formation rate of glucuronide metabolites from 1'- and 4-hydroxymidazolam in 25 HLMs showed that hydroxymidazolam glucuronidation is correlated with UGT1A4-mediated lamotrigine glucuronidation and UGT2B7-mediated diclofenac glucuronidation activity. Taken together, these findings indicate that UGT1A4, 2B4, and 2B7 are major isoforms responsible for glucuronide conjugate formation from 1'- and 4-hydroxymidazolam, which are the two major oxidative metabolites of midazolam. PMID:20713656

Seo, Kyung-Ah; Bae, Soo Kyung; Choi, Young-Kil; Choi, Chang Soo; Liu, Kwang-Hyeon; Shin, Jae-Gook

2010-11-01

161

Transport of estradiol-17?-glucuronide, estrone-3-sulfate and taurocholate across the endoplasmic reticulum membrane: evidence for different transport systems?  

PubMed Central

Important reactions of drug metabolism, including UGT mediated glucuronidation and steroidsulfatase mediated hydrolysis of sulfates, take place in the endoplasmic reticulum (ER) of hepatocytes. Consequently, UGT generated glucuronides, like estradiol-17?-glucuronide, have to be translocated back into the cytoplasm to reach their site of excretion. Also steroidsulfatase substrates, including estrone-3-sulfate, have to cross the ER membrane to reach their site of hydrolysis. Based on their physicochemical properties such compounds are not favored for passive diffusion and therefore likely necessitate transport system(s) to cross the ER membrane in either direction. The current study aims to investigate the transport of taurocholate, estradiol-17?-glucuronide, and estrone-3-sulfate in smooth (SER) and rough (RER) endoplasmic reticulum membrane vesicles isolated from Wistar and TR? rat liver. Time-dependent and bidirectional transport was demonstrated for taurocholate, showing higher uptake rates in SER than RER vesicles. For estradiol-17?-glucuronide a fast time-dependent efflux with similar efficiencies from SER and RER but no clear protein-mediated uptake was shown, indicating an asymmetric transport system for this substrate. Estrone-3-sulfate uptake was time-dependent and higher in SER than in RER vesicles. Inhibition of steroidsulfatase mediated estrone-3-sulfate hydrolysis decreased estrone-3-sulfate uptake but had no effect on taurocholate or estradiol-17?-glucuronide transport. Based on inhibition studies and transport characteristics, three different transport mechanisms are suggested to be involved in the transport of taurocholate, estrone-3-sulfate and estradiol-17?-glucuronide across the ER membrane. PMID:24406246

Wlcek, Katrin; Hofstetter, Lia; Stieger, Bruno

2014-01-01

162

Biotransformation of Bisphenol AF to Its Major Glucuronide Metabolite Reduces Estrogenic Activity  

PubMed Central

Bisphenol AF (BPAF), an endocrine disrupting chemical, can induce estrogenic activity through binding to estrogen receptor (ER). However, the metabolism of BPAF in vivo and the estrogenic activity of its metabolites remain unknown. In the present study, we identified four metabolites including BPAF diglucuronide, BPAF glucuronide (BPAF-G), BPAF glucuronide dehydrated and BPAF sulfate in the urine of Sprague-Dawley (SD) rats. BPAF-G was further characterized by nuclear magnetic resonance (NMR). After treatment with a single dose of BPAF, BPAF was metabolized rapidly to BPAF-G, as detected in the plasma of SD rats. Biotransformation of BPAF to BPAF-G was confirmed with human liver microsomes (HLM), and Vmax of glucuronidation for HLM was 11.6 nmol/min/mg. We also found that BPAF glucuronidation could be mediated through several human recombinant UDP-glucuronosyltransferases (UGTs) including UGT1A1, UGT1A3, UGT1A8, UGT1A9, UGT2B4, UGT2B7, UGT2B15 and UGT2B17, among which UGT2B7 showed the highest efficiency of glucuronidation. To explain the biological function of BPAF biotransformation, the estrogenic activities of BPAF and BPAF-G were evaluated in ER-positive breast cancer T47D and MCF7 cells. BPAF significantly stimulates ER-regulated gene expression and cell proliferation at the dose of 100 nM and 1 ?M in breast cancer cells. However, BPAF-G did not show any induction of estrogenic activity at the same dosages, implying that formation of BPAF-G is a potential host defense mechanism against BPAF. Based on our study, biotransformation of BPAF to BPAF-G can eliminate BPAF-induced estrogenic activity, which is therefore considered as reducing the potential threat to human beings. PMID:24349450

Yin, Jie; Zhang, Jing; Feng, Yixing; Shao, Bing

2013-01-01

163

Tissue and species differences in the glucuronidation of glabridin with UDP-glucuronosyltransferases.  

PubMed

Glabridin (GA) has gained wide application in the cosmetics and food industry. This study was performed to investigate its metabolic inactivation and elimination by glucuronidation by use of liver and intestine microsomes from humans (HLM and HIM) and rats (RLM and RIM), and liver microsomes from cynomolgus monkeys and beagle dogs (CyLM and DLM). Both hydroxyl groups at the C2 and C4 positions of the B ring are conjugated to generate two mono-glucuronides (M1 and M2). HIM, RIM and RLM showed the most robust activity in catalyzing M2 formation with intrinsic clearance values (Clint) above 2000?L/min/mg, with little measurable M1 formation activity. DLM displayed considerable activity both in M1 and M2 formation, with Clint values of 71 and 214?L/min/mg, respectively, while HLM and CyLM exhibited low activities in catalyzing M1 and M2 formation, with Clint values all below 20?L/min/mg. It is revealed that UGT1A1, 1A3, 1A9, 2B7, 2B15 and extrahepatic UGT1A8 and 1A10 are involved in GA glucuronidation. Nearly all UGTs preferred M2 formation except for UGT1A1. Notably, UGT1A8 displayed the highest activity with a Clint value more than 5-fold higher than the other isoforms. Chemical inhibition studies, using selective inhibitors of UGT1A1, 1A9, 2B7 and 1A8, further revealed that UGT1A8 contributed significantly to intestinal GA glucuronidation in humans. In summary, this in vitro study demonstrated large species differences in GA glucuronidation by liver and intestinal microsomes, and that intestinal UGTs are important for the pathway in humans. PMID:25765239

Guo, Bin; Fang, Zhongze; Yang, Lu; Xiao, Ling; Xia, Yangliu; Gonzalez, Frank J; Zhu, Liangliang; Cao, Yunfeng; Ge, Guangbo; Yang, Ling; Sun, Hongzhi

2015-04-25

164

Mass spectrometric characterization of glucuronides formed by a new concept, combining Cunninghamella elegans with TEMPO.  

PubMed

A new concept for the production of drug glucuronides is presented and the products formed were characterized using ultra high performance liquid chromatography-high resolution mass spectrometry (UPLC-HRMS). Glucuronic acid conjugates are important phase II metabolites of a wide range of drugs. There is a lack of commercially available glucuronides and classic synthetic methods are tedious and expensive. Thus, new methods of glucuronide synthesis are needed. Selective androgen receptor modulators (SARMs) of the aryl propionamide class were used as model compounds and were incubated with the fungus Cunninghamella elegans which was previously known to conjugate drugs with glucose. The resulting glucoside metabolites were then oxidized with tetramethylpiperidinyl-1-oxy (TEMPO). UPLC-HRMS analysis showed that the peaks corresponding to the glucosides had disappeared after the reaction and were replaced by peaks with m/z consistent with the corresponding glucuronic acid conjugates. The MS/MS spectra of the reaction products were investigated and the observed fragment ion pattern corroborated the suggested structural change. A comparison in terms of retention times and product ion spectra between the glucuronides formed by the new method and those produced by liver microsomes indicated that the conjugates from the two different sources were identical, thus demonstrating the human relevance of the presented technique. Furthermore, the glucuronides formed by the presented method were readily hydrolyzed by ?-glucuronidase which further gave evidence as to the fact that they were of ? configuration. The investigated method was easy to perform, required a low input of work and had a low cost. PMID:23867089

Rydevik, Axel; Bondesson, Ulf; Thevis, Mario; Hedeland, Mikael

2013-10-01

165

Molecular Structure of Ethyl acetate  

NSDL National Science Digital Library

Ethyl acetate is a colorless, volatile liquid with a mild and fragrant odor. It is used as solvent in chemistry laboratories but can also be found in many household products such as paints, coatings, and adhesives. The compound is also used in some extraction processes such as decaffeination or purification of antibiotics. It is present in both nail polish and removers. Some synthetic fruit essences may contain this and other esters. Etymologists like to use this solvent for insect collecting as the vapor kill the insect quickly and keep it soft for mounting.

2006-03-08

166

Enhanced ethyl butyrate production using immobilized lipase.  

PubMed

In this study, the production of ethyl butyrate was investigated by using immobilized lipase enzyme in shake flasks. In order to determine optimum conditions for the production, response surface methodology was used. The model indicated the optimum conditions for maximum conversion (9.1%) at the 0.31 M substrate concentration, acid- alcohol molar ratio of 0.49, immobilized enzyme 25% (w/v) at 35°C, for 3 hours which were in good agreement with the experimental value. At the end of the 55 hours conversion was obtained as 61.3%. When Na2HPO4 was used in reaction medium conversion increased to 90.3% for 55 hours. PMID:23305408

Ate?, Selma; Türk, Burcu; Bayraktar, Emine; Güvenç, Afife

2013-10-01

167

Reactivity of 2-ethyl-1-hexanol in the atmosphere.  

PubMed

Rate coefficients at room temperature for the reaction of 2-ethyl-1-hexanol with OH and NO(3) radicals and with Cl atoms have been determined in a 150 L PTFE chamber using GC-FID/SPME and FTIR as detection systems. The rate coefficients k (in units of cm(3) molecule(-1) s(-1)) obtained were: (1.13 +/- 0.31) 10(-11) for the OH reaction, (2.93 +/- 0.92) 10(-15) for the NO(3) reaction and (1.88 +/- 0.25) 10(-10) for the Cl reaction. Despite the high concentrations of 2-ethyl-1-hexanol, especially in indoor air, this is the first kinetic study carried out to date for these reactions. The results are consistent with the expected reactivity given the chemical structure of 2-ethyl-1-hexanol. Calculated atmospheric lifetimes reveal that the dominant loss process for 2-ethyl-1-hexanol is clearly the daytime reaction with the hydroxyl radical. PMID:20237722

Gallego-Iniesta García, María Paz; Moreno Sanroma, Alberto; Martín Porrero, María Pilar; Tapia Valle, Araceli; Cabañas Galán, Beatriz; Salgado Muñoz, María Sagrario

2010-04-01

168

Enantioselective Metabolism of Quizalofop-Ethyl in Rat  

PubMed Central

The pharmacokinetic and distribution of the enantiomers of quizalofop-ethyl and its metabolite quizalofop-acid were studied in Sprague-Dawley male rats. The two pairs of enantiomers were determined using a validated chiral high-performance liquid chromatography method. Animals were administered quizalofop-ethyl at 10 mg kg?1 orally and intravenously. It was found high concentration of quizalofop-acid in the blood and tissues by both intragastric and intravenous administration, and quizalofop-ethyl could not be detected through the whole study which indicated a quick metabolism of quizalofop-ethyl to quizalofop-acid in vivo. In almost all the samples, the concentrations of (+)-quizalofop-acid exceeded those of (?)-quizalofop-acid. Quizalofop-acid could still be detected in the samples even at 120 h except in brain due to the function of blood-brain barrier. Based on a rough calculation, about 8.77% and 2.16% of quizalofop-acid were excreted through urine and feces after intragastric administration. The oral bioavailability of (+)-quizalofop-acid and (?)-quizalofop-acid were 72.8% and 83.6%. PMID:24964043

Liang, Yiran; Wang, Peng; Liu, Donghui; Shen, Zhigang; Liu, Hui; Jia, Zhixin; Zhou, Zhiqiang

2014-01-01

169

The pharmacokinetics of naproxen, its metabolite O-desmethylnaproxen, and their acyl glucuronides in humans. Effect of cimetidine.  

PubMed Central

1. The pharmacokinetics of 500 mg naproxen given orally were described in 10 subjects using a direct h.p.l.c. analysis of the acyl glucuronide conjugates of naproxen and its metabolite O-desmethylnaproxen. 2. The mean elimination half-life of naproxen was 24.7 +/- 6.4 h (range 7 to 36 h). 3. Naproxen acyl glucuronide accounted for 50.8 +/- 7.3% of the dose recovered in the urine, its isomerised conjugate isoglucuronide for 6.5 +/- 2.0%, O-desmethylnaproxen acyl glucuronide for 14.3 +/- 3.4%, and its isoglucuronide for 5.5 +/- 1.3%. Naproxen and O-desmethylnaproxen were excreted in negligible amounts (< 1%). 4. Even though the urine pH of the subjects was kept acid in order to stabilize the acyl glucuronides, isomerisation took place in blood. 5. The extents of plasma binding of the unconjugated compounds were 98% (naproxen) and 100% (O-desmethylnaproxen), while naproxen acyl glucuronide binding was 92%; that of its isomer isoglucuronide 66%. O-desmethylnaproxen acyl glucuronide was 72% bound and its isoglucuronide was 42% bound. 6. Cimetidine (400 mg twice daily) decreased the t1/2 of naproxen by 39-60% (mean 47.3 +/- 11.5%; P = 0.0014) from 24.7 +/- 6.4 h to 13.2 +/- 1.0 h. It increased (10%) the urinary recovery of naproxen acyl glucuronide (P = 0.0492). The urinary recoveries of naproxen isoglucuronide and O-desmethylnaproxen acyl glucuronide remained unchanged. PMID:8512758

Vree, T B; Van Den Biggelaar-Martea, M; Verwey-Van Wissen, C P; Vree, M L; Guelen, P J

1993-01-01

170

CCXVII. Separation and characterization of bile acid 3-glucuronides in human urine by high-performance liquid chromatography.  

PubMed

The separation and characterization of unconjugated and conjugated bile acid 3-glucuronides in biological fluids without prior deconjugation by high-performance liquid chromatography (HPLC) are described. A urine sample from a patient with obstructive jaundice was passed through a Sep-Pak C18 cartridge and was separated into groups by ion-exchange chromatography on a lipophilic gel, piperidinohydroxypropyl Sephadex LH-20, providing the glucuronide fraction. Subsequent resolution into individual 3-glucuronides was attained by HPLC on muBondapak C18 and Shodex ODS Pak F-411 columns. The 3-glucuronides of cholate, deoxycholate, chenodeoxycholate, glycocholate, glycochenodeoxycholate and taurochenodeoxycholate were identified on the basis of their behaviour in HPLC using mobile phases of different pH. The enzymatic hydrolysis of these glucuronides and derivatization of deconjugated bile acids with 1-anthroyl nitrile followed by chromatographic separation on a Cosmosil 5C18 column with fluorescence detection were carried out for unequivocal characterization. The ratio of unconjugated, glyco- and tauro-conjugated bile acid 3-glucuronides excreted in urine was found to be ca. 2:3:1. PMID:4086595

Goto, J; Suzaki, K; Ebihara, M; Nambara, T; Masu, A

1985-12-13

171

Hormonal monitoring of early pregnancy by a direct radioimmunoassay of steroid glucuronides in first morning urine  

SciTech Connect

The usefulness of the direct 4-hour radioimmunoassay of estriol-16-glucuronide (E/sub 3/G) and pregnanediol-3-glucuronide (P/sub 2/G) in first morning urine (FMU) for establishing a prognosis of the early pregnancy outcome was evaluated in 106 patients that became pregnant. Microaliquots of FMU were serially assayed from day 3 of the conception cycle until day 80 of pregnancy. The E/sub 3/G and P/sub 2/G profiles of 19 pregnancies which terminated in spontaneous abortion with either a diagnosis of the blighted ovum syndrome (n = 11) or presumption of a corpus luteum/trophoblast failure (n = 8) have been compared with those of clinically normal pregnancies (n = 87). Normal pregnancies displayed typical patterns of E/sub 3/G and P/sub 2/G development, while variations were observed in abortive events that reflected changes of the fetoplacental unit.

Mendizabal, A.F.; Quiroga, S.; Farinati, Z.; Lahoz, M.; Nagle, C.

1984-11-01

172

40 CFR 180.441 - Quizalofop ethyl; tolerances for residues.  

Code of Federal Regulations, 2012 CFR

...Tolerances are established for residues of the herbicide quizalofop ethyl, including its...Tolerances are established for residues of the herbicide quizalofop ethyl, including...registration are established for residues of the herbicide quizalofop ethyl,...

2012-07-01

173

40 CFR 180.441 - Quizalofop ethyl; tolerances for residues.  

Code of Federal Regulations, 2013 CFR

...Tolerances are established for residues of the herbicide quizalofop ethyl, including its...Tolerances are established for residues of the herbicide quizalofop ethyl, including...registration are established for residues of the herbicide quizalofop ethyl,...

2013-07-01

174

40 CFR 180.441 - Quizalofop ethyl; tolerances for residues.  

Code of Federal Regulations, 2014 CFR

...Tolerances are established for residues of the herbicide quizalofop ethyl, including its...Tolerances are established for residues of the herbicide quizalofop ethyl, including...registration are established for residues of the herbicide quizalofop ethyl,...

2014-07-01

175

Microsomal immobilized-enzyme-reactor for on-line production of glucuronides in a HPLC column  

Microsoft Academic Search

Nonsolubilized rat liver microsomes have been noncovalently immobilized on an immobilized artifical membrane (IAM) HPLC chromatographic support to create a microsomal immobilized enzyme reactor (MIC-IMER). The MIC-IMER has been used for the on-line synthesis and analysis of Phase II metabolism conjugates. The activity of the MIC-IMER was investigated by following thein vitro glucuronidation of two well known UDP-glucuronosyltransferase (UDPGT; EC

T. Alebi?-Kolbah; I. W. Wainer

1993-01-01

176

Interindividual variation in the capacity-limited renal glucuronidation of probenecid by humans  

Microsoft Academic Search

A dose of 1,000 mg probenecid was administered orally to 14 human volunteers in order to quantify the maximal rate of formation and excretion of probenecid acyl glucuronide in the urine. Probenecid showed dose-dependent pharmacokinetics. Plasma protein binding of probenecid was high, being somewhat higher in males (90.7±1.4%) than in females (87.9±1.4%; p=0.0019). It was shown that probenecid is metabolized

T. B. Vree; E. W. J. Van Ewijk-Beneken Kolmer; E. W. Wuis; Y. A. Hekster; M. M. M. Broekman

1993-01-01

177

?-Glucuronidase activity and mitochondrial dysfunction: the sites where flavonoid glucuronides act as anti-inflammatory agents.  

PubMed

Epidemiological and experimental studies suggest that the consumption of flavonoid-rich diets decreases the risk of various chronic diseases such as cardiovascular diseases. Although studies on the bioavailability of flavonoids have been well-characterized, the tissue and cellular localizations underlying their biological mechanisms are largely unknown. The development and application of novel monoclonal antibodies revealed that macrophages could be the major target of dietary flavonoids in vivo. Using macrophage-like cell lines in vitro, we examined the molecular basis of the interaction between the macrophages and flavonoids, especially the glucuronide metabolites. We have found that extracellular ?-glucuronidase secreted from macrophages is essential for the bioactivation of the glucuronide conjugates into the aglycone, and that the enzymatic activity, which requires an acidic pH, is promoted by the increased secretion of lactate in response to the mitochondrial dysfunction. This review describes our recent findings indicating the molecular mechanisms responsible for the anti-inflammatory activity of dietary flavonoids within the inflammation sites. We propose that the extracellular activity of ?-glucuronidase associated with the status of the mitochondrial function in the target cells might be important biomarkers for the specific sites where the glucuronides of dietary flavonoids can act as anti-atherosclerotic and anti-inflammatory agents in vivo. PMID:24895476

Kawai, Yoshichika

2014-05-01

178

Mechanism of biosynthesis of thio-?-d-glucuronides and thio-?-d-glucosides  

PubMed Central

1. The thio-?-d-glucosiduronic acids (thio-?-glucuronides) of o-aminothiophenol, diethyldithiocarbamic acid, p-nitrothiophenol and thiophenol are formed biosynthetically in broken- and intact-cell preparations of mouse liver. 2. For this biosynthesis to occur in homogenates or microsomal fractions, UDP-glucuronic acid was required during incubation; glucose, glucuronic acid or UDP could not replace it. UDP was a product of the reaction. 3. The biosynthetic mechanism linking glucuronic acid to thiol and carbodithioic groups therefore requires UDP-glucuronyltransferase activity and resembles that forming the various types of O-glucuronides. 4. An analogous enzymic mechanism employing UDP-glucose synthesizes the thio-?-d-glucosides of diethyldithiocarbamic acid and thiophenol in gut preparations of the mollusc Arion ater; this mechanism resembles that forming the O-glucosides. The thio-?-d-glucosides are formed also in intact cells. 5. As expected from the distribution of O-glycosides, S-glucuronides of these aglycones were not detectable with the invertebrate, nor were the S-glucosides with the vertebrate. 6. Despite their similar biosyntheses, S- and O-?-glycosides differ in susceptibility to hydrolysis by ?-glycosidases. Rat preputial-gland ?-glucuronidase hydrolysed thioglucuronides of o-aminothiophenol, diethyldithiocarbamic acid and p-nitrothiophenol, hydrolysis being inhibited by glucarolactone; the thioglucuronide of thiophenol was not hydrolysed by preputial-gland or liver ?-glucuronidase. The two S-glucosides resisted hydrolysis by ?-glucosidase from almond emulsin. PMID:4658987

Dutton, G. J.; Illing, H. P. A.

1972-01-01

179

Estimation of quizalofop ethyl residues in black gram (Vigna mungo L.) by gas liquid chromatography.  

PubMed

Quizalofop ethyl, a phenoxy propionate herbicide is used for post emergence control of annual and perennial grass weeds in broad-leaved crops in India. The experiments were designed to study the harvest time residues of quizalofop ethyl in black gram for two seasons. At harvest time, the residues of quizalofop ethyl on black gram seed, foliage and soil were found to be below the determination limit of 0.01 mg kg(-1) following a single application of the herbicide at 50 and 100 g a.i. ha(-1) for both the periods. Application of the herbicide is quite safe from a consumer and environmental point of view. PMID:24275886

Mandal, Kousik; Sahoo, Sanjay Kumar; Battu, R S; Singh, Balwinder

2014-01-01

180

IN VIVO RATE OF PHENOL GLUCURONIDATION BY RAINBOW TROUT  

EPA Science Inventory

Induction of vitellogenin (VTG) in male fish has become an accepted biomarker for xenoestrogenicity. This study utilized the male rainbow trout liver slice model to determine the estrogenicity of parent compound, methoxychlor (MXC) and metabolites, di-hydroxy methoxychlor (HPTE) ...

181

Uptake of Ethyl Alcohol Vapor in Sulfuric Acid Solutions  

NASA Astrophysics Data System (ADS)

The uptake of ethyl alcohol vapor in liquid sulfuric acid has been investigated over the composition range of 40 - 80 wt % H2SO4 and between the temperatures of 193-273 K. Laboratory studies were performed using a flow-tube reactor coupled to an electron-impact ionization mass spectrometer for detection of ethanol and possible reaction products, ethyl hydrogen sulfate and diethyl sulfate. The uptake coefficients (gamma) have been measured and found to vary from 0.018 to 0.065, depending upon the acid composition and temperature. For example, at concentrated acids greater than 70 wt % and dilute solutions (<70 wt %) colder than 210 K, the gamma values are approaching ~ 0.06. Under other conditions, the gamma values are smaller. The adsorption and thermal desorption measurements have been used to distinguish the possible uptake mechanisms, either solubility or reactive uptake. The results suggest that reactive uptakes are greater than 50 % under all conditions. For dilute acids, we also determine the effective Henry's law constants (H*). We will compare the results with the uptake of gaseous methyl alcohol and acetone in H2SO4 determined previously in our laboratory. The potential implications to the budget of ethyl alcohol in the global troposphere will also be discussed.

Leu, M.

2002-12-01

182

Process for the preparation of ethyl benzene  

DOEpatents

Ethyl benzene is produced in a catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 50 C to 300 C, using as the catalyst a mole sieve characterized as acidic by feeding ethylene to the catalyst bed while benzene is conveniently added through the reflux to result in a molar excess present in the reactor to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene and diethyl benzene in the bottoms. The bottoms are fractionated, the ethyl benzene recovered and the bottoms are contacted with benzene in the liquid phase in a fixed bed straight pass reactor under conditions to transalkylate the benzene thereby converting most of the diethyl benzene to ethyl benzene which is again separated and recovered. 2 figs.

Smith, L.A. Jr.; Arganbright, R.P.; Hearn, D.

1995-12-19

183

Process for the preparation of ethyl benzene  

DOEpatents

Ethyl benzene is produced in a catalyst bed under 0.25 to 50 atmospheres of pressure and at temperatures in the range of 50.degree. C. to 300.degree. C., using as the catalyst a mole sieve characterized as acidic by feeding ethylene to the catalyst bed while benzene is conveniently added through the reflux to result in a molar excess present in the reactor to that required to react with ethylene, thereby reacting substantially all of the ethylene and recovering benzene as the principal overhead and ethyl benzene and diethyl benzene in the bottoms. The bottoms are fractionated, the ethyl benzene recovered and the bottoms are contacted with benzene in the liquid phase in a fixed bed straight pass reactor under conditions to transalkylate the benzene thereby converting most of the diethyl benzene to ethyl benzene which is again separated and recovered.

Smith, Jr., Lawrence A. (Houston, TX); Arganbright, Robert P. (Houston, TX); Hearn, Dennis (Houston, TX)

1995-01-01

184

27 CFR 21.108 - Ethyl ether.  

Code of Federal Regulations, 2010 CFR

...FORMULAS FOR DENATURED ALCOHOL AND RUM Specifications for Denaturants § 21.108 Ethyl ether. (a) Odor. Characteristic odor. (b) Specific gravity at 15.56 °/15.56 °C. Not more than 0.728. [T.D. ATF-133,...

2010-04-01

185

Glucuronidated Quercetin Lowers Blood Pressure in Spontaneously Hypertensive Rats via Deconjugation  

PubMed Central

Background Chronic oral quercetin reduces blood pressure and restores endothelial dysfunction in hypertensive animals. However, quercetin (aglycone) is usually not present in plasma, because it is rapidly metabolized into conjugated, mostly inactive, metabolites. The aim of the study is to analyze whether deconjugation of these metabolites is involved in the blood pressure lowering effect of quercetin. Methodology/Principal Findings We have analyzed the effects on blood pressure and vascular function in vitro of the conjugated metabolites of quercetin (quercetin-3-glucuronide, Q3GA; isorhamnetin-3-glucuronide, I3GA; and quercetin-3?-sulfate, Q3'S) in spontaneously hypertensive rats (SHR). Q3GA and I3GA (1 mg/kg i.v.), but not Q3'S, progressively reduced mean blood pressure (MBP), measured in conscious SHR. The hypotensive effect of Q3GA was abolished in SHR treated with the specific inhibitor of ?-glucuronidase, saccharic acid 1,4-lactone (SAL, 10 mg/ml). In mesenteric arteries, unlike quercetin, Q3GA had no inhibitory effect in the contractile response to phenylephrine after 30 min of incubation. However, after 1 hour of incubation Q3GA strongly reduced this contractile response and this effect was prevented by SAL. Oral administration of quercetin (10 mg/Kg) induced a progressive decrease in MBP, which was also suppressed by SAL. Conclusions Conjugated metabolites are involved in the in vivo antihypertensive effect of quercetin, acting as molecules for the plasmatic transport of quercetin to the target tissues. Quercetin released from its glucuronidated metabolites could be responsible for its vasorelaxant and hypotensive effect. PMID:22427863

Galindo, Pilar; Rodriguez-Gómez, Isabel; González-Manzano, Susana; Dueñas, Montserrat; Jiménez, Rosario; Menéndez, Carmen; Vargas, Félix; Tamargo, Juan; Santos-Buelga, Celestino; Pérez-Vizcaíno, Francisco; Duarte, Juan

2012-01-01

186

Determination by liquid chromatography with fluorescence detection of total 7-ethyl-10-hydroxy-camptothecin (SN-38) in beagle dog plasma after intravenous administration of liposome-based SN-38 (LE-SN38).  

PubMed

An HPLC- fluorescence method to quantitate total 7-ethyl-10-hydroxy-camptothecin (SN-38) in beagle dog plasma spiked with liposome based formulation of SN-38 (LE-SN38) and using camptothecin (CPT) as the internal standard (I.S.) was developed and validated to support pharmacokinetics/toxicokinetics studies. Sample preparation was done by protein precipitation using acetonitrile with 0.5% acetic acid. The supernatant was evaporated, and reconstituted in acetonitrile-20 mM ammonium acetate, pH 3.5 (20:80, v/v). When injected onto a Zorbax SB-C(18) HPLC column SN-38 as well as I.S. were detected by fluorescence using an excitation at 368 nm and emission at 515 nm. The SN-38 concentrations in samples were calculated from a standard curve of peak area ratios of SN-38 to the I.S. using weighted linear regression. The sensitivity limit for SN-38 was 1.00 ng/ml in beagle dog plasma with a precision (expressed as relative standard deviation) of 12.4% and an accuracy (expressed as analytical recovery) of 104%. The assay was linear within the standard curve range of 1-750 ng/ml. Acceptable precision and accuracy were also obtained for concentrations over the balance of the standard curve range from between-run and within-run calculations. PMID:12798168

Guo, W; Ahmad, A; Khan, S; Dahhani, F; Wang, Y F; Ahmad, I

2003-07-01

187

Urinary Excretion of Cyanidin Glucosides and Glucuronides in Healthy Humans After Elderberry Juice Ingestion.  

PubMed

In a pilot study with 6 females and 1 male, the metabolism of various cyanidin glucosides after oral administration of elderberry juice was investigated. The anthocyanin metabolites were detected in urinary excretion. After ingestion of a bolus quantity of $3.57$ g total anthocyanins in a $150$ mL elderberry juice concentrate, $0.053$ % of the administered dose was excreted in urine as glucosidically bound cyanidins within the first 5 hours. Only $0.003$ % of the ingested anthocyanin glucosides was excreted as cyanidin glucuronide, suggesting that this conversion step might be of minor importance in urinary excretion. PMID:15577200

Bitsch, Roland; Netzel, Michael; Sonntag, Susanne; Strass, Gabriele; Frank, Thomas; Bitsch, Irmgard

2004-01-01

188

Identification of Recent Cannabis Use: Whole-Blood and Plasma Free and Glucuronidated Cannabinoid Pharmacokinetics following Controlled Smoked Cannabis Administration  

PubMed Central

BACKGROUND ?9-Tetrahydrocannabinol (THC) is the most frequently observed illicit drug in investigations of accidents and driving under the influence of drugs. THC-glucuronide has been suggested as a marker of recent cannabis use, but there are no blood data following controlled THC administration to test this hypothesis. Furthermore, there are no studies directly examining whole-blood cannabinoid pharmacokinetics, although this matrix is often the only available specimen. METHODS Participants (9 men, 1 woman) resided on a closed research unit and smoked one 6.8% THC cannabis cigarette ad libitum. We quantified THC, 11-hydroxy-THC (11-OH-THC), 11-nor-9-carboxy-THC (THCCOOH), cannabidiol (CBD), cannabinol (CBN), THC-glucuronide and THCCOOH-glucuronide directly in whole blood and plasma by liquid chromatography/ tandem mass spectrometry within 24 h of collection to obviate stability issues. RESULTS Median whole blood (plasma) observed maximum concentrations (Cmax) were 50 (76), 6.4 (10), 41 (67), 1.3 (2.0), 2.4 (3.6), 89 (190), and 0.7 (1.4) ?g/L 0.25 h after starting smoking for THC, 11-OH-THC, THCCOOH, CBD, CBN, and THCCOOH-glucuronide, respectively, and 0.5 h for THC-glucuronide. At observed Cmax, whole-blood (plasma) detection rates were 60% (80%), 80% (90%), and 50% (80%) for CBD, CBN, and THC-glucuronide, respectively. CBD and CBN were not detectable after 1 h in either matrix (LOQ 1.0 ?g/L). CONCLUSIONS Human whole-blood cannabinoid data following cannabis smoking will assist whole blood and plasma cannabinoid interpretation, while furthering identification of recent cannabis intake. PMID:21836075

Schwope, David M.; Karschner, Erin L.; Gorelick, David A.; Huestis, Marilyn A.

2013-01-01

189

Amide N-glucuronidation of MaxiPost catalyzed by UDP-glucuronosyltransferase 2B7 in humans.  

PubMed

MaxiPost [(3S)-(+)-(5-chloro-2-methoxyphenyl)-1,3-dihydro-3-fluoro-6-(trifluoromethyl)-2H-indole-2-one), or BMS-204352)] is a potent and specific maxi-K channel opener for potential use to treat stroke. This article describes structural characterization of a major human N-glucuronide metabolite of BMS-204352 and identification of the enzyme responsible for the N-glucuronidation reaction. After intravenous administrations of [(14)C]BMS-204352 (10 mg, 50 microCi) to eight healthy human subjects, one major metabolite M representing an average of 17% of the radioactive dose was excreted in pooled urine collected over 0 to 336 h after dosing. A major biliary metabolite of dogs dosed with [(14)C]BMS-204352 (5 mg/kg), which represented about 33% of the dose, has the same retention time and the same tandem mass spectrometry fragmentation pattern as the human urinary metabolite M. Four hundred fifty micrograms of the metabolite was isolated from the dog bile and analyzed by NMR. Long-range (1)H-(13)C NMR experimentation indicated that the glucuronic acid moiety was at the nitrogen site. The N-glucuronide of BMS-204352 was stable up to 24 h at 37 degrees C in the incubations at different pH values (3.0, 7.4, and 9.0) and with glucuronidases from Escherichia coli and Helix pomatia. Of the seven human UDP-glucuronosyltransferases (UGT) isozymes (1A1, 1A3, 1A4, 1A6, 1A7, 1A10, and 2B7) tested, only UGT2B7 produced metabolite M. UGT2B7-catalyzed N-glucuronidation of BMS-204352 exhibited Michaelis-Menten kinetics with a K(m) of 14.2 microM and V(max) of 0.29 nmol/min. mg of protein. Collectively, these results suggest that amide N-glucuronidation, a major elimination pathway of MaxiPost, is catalyzed by UGT2B7 in humans. This N-glucuronide represents a fully characterized amide N-glucuronide, and glucuronidation at the nitrogen represents a newly identified conjugation reaction for UGT2B7. PMID:15100177

Zhang, Donglu; Zhao, Weiping; Roongta, Vikram A; Mitroka, James G; Klunk, Lewis J; Zhu, Mingshe

2004-05-01

190

A sensitive and rapid liquid chromatography tandem mass spectrometry method for quantitative determination of 7-ethyl-10-hydroxycamptothecin (SN-38) in human plasma containing liposome-based SN-38 (LE-SN38).  

PubMed

7-Ethyl-10-hydroxycamptothecin (SN-38) is an active metabolite of Irinotecan (CPT-11), an anticancer pro-drug. To support clinical pharmacokinetic studies for liposome based formulation of SN-38 (LE-SN38) in cancer patients, a rapid, simple and sensitive liquid chromatography tandem mass spectrometry (LC-MS/MS) method has been developed and validated for the quantification of total SN-38 in human plasma. Sample preparation was carried out by one-step protein precipitation using cold acetonitrile with 0.5% acetic acid (v/v). Camptothecin was used as an internal standard (IS). Chromatographic separation of SN-38 and IS was achieved using a Synergi Hydro-RP column (C(18), 50 x 2 mm, 4 micro m), with a gradient elution of acetonitrile and 0.1% acetic acid. After ionization in electrospray source (positive ions), the acquisition was performed in the multiple reactions monitoring mode. Quantitation was accomplished using the precursor-->product ion combinations of m/z 393.1-->349.2 for SN-38 and 349.1-->305.1 for IS. The quantification limit of 0.05 ng/mL was achieved by using much lower volume (0.2 mL) of plasma and in the presence of LE-SN38. The method was validated over the concentration range of 0.05-400 ng/mL. Accuracy was within +/-12% of nominal at all concentration levels. Inter-day and intra-day precisions expressed as percentage coefficient of variation (%CVs) for quality control (QC) samples were less than 14 and 5%, respectively. PMID:14648604

Khan, Sumsullah; Ahmad, Ateeq; Ahmad, Imran

2003-12-01

191

Elevated concentrations of morphine 6-beta-D-glucuronide in brain extracellular fluid despite low blood–brain barrier permeability  

PubMed Central

This study was done to find out how morphine 6-beta-D-glucuronide (M6G) induces more potent central analgesia than morphine, despite its poor blood–brain barrier (BBB) permeability. The brain uptake and disposition of these compounds were investigated in plasma and in various brain compartments: extracellular fluid (ECF), intracellular space (ICS) and cerebrospinal fluid (CSF). Morphine or M6G was given to rats at 10?mg?kg?1 s.c. Transcortical microdialysis was used to assess their distributions in the brain ECF. Conventional tissue homogenization was used to determine the distribution in the cortex and whole brain. These two procedures were combined to estimate drug distribution in the brain ICS. The blood and CSF pharmacokinetics were also determined. Plasma concentration data for M6G were much higher than those of morphine, with Cmax and AUC 4–5 times more higher, Tmax shorter, and VZf?1 (volume of distribution) and CL f?1 (clearance) 4–6 times lower. The concentrations of the compounds in various brain compartments also differed: AUC values for M6G were lower than those of morphine in tissue and CSF and higher in brain ECF. AUC values in brain show that morphine levels were four times higher in ICS than in ECF, whereas M6G levels were 125 higher in ECF than in ICS. Morphine entered brain cells, whereas M6G was almost exclusively extracellular. This high extracellular concentration, coupled with extremely slow diffusion into the CSF, indicates that M6G was predominantly trapped in the extracellular fluid and therefore durably available to bind at opioid receptors. PMID:10556926

Stain-Texier, Frédérique; Boschi, Gabrielle; Sandouk, Pierre; Scherrmann, Jean-Michel

1999-01-01

192

Reverse-phase h.p.l.c. separation, quantification and preparation of bilirubin and its conjugates from native bile. Quantitative analysis of the intact tetrapyrroles based on h.p.l.c. of their ethyl anthranilate azo derivatives.  

PubMed

We describe a facile and sensitive reverse-phase h.p.l.c. method for analytical separation of biliary bile pigments and direct quantification of unconjugated bilirubin (UCB) and its monoglucuronide (BMG) and diglucuronide (BDG) conjugates in bile. The method can be 'scaled up' for preparative isolation of pure BDG and BMG from pigment-enriched biles. We employed an Altex ultrasphere ODS column in the preparative steps and a Waters mu-Bondapak C18 column in the separatory and analytical procedures. Bile pigments were eluted with ammonium acetate buffer, pH 4.5, and a 20 min linear gradient of 60-100% (v/v) methanol at a flow rate of 2.0 ml/min for the preparative separations and 1.0 ml/min for the analytical separations. Bile pigments were eluted in order of decreasing polarity (glucuronide greater than glucose greater than xylose conjugates greater than UCB) and were chemically identified by t.l.c. of their respective ethyl anthranilate azo derivatives. Quantification of UCB was carried out by using a standard curve relating a range of h.p.l.c. integrated peak areas to concentrations of pure crystalline UCB. A pure crystalline ethyl anthranilate azo derivative of UCB (AZO . UCB) was employed as a single h.p.l.c. reference standard for quantification of BMG and BDG. We demonstrate that: separation and quantification of biliary bile pigments are rapid (approximately 25 min); bile pigment concentrations ranging from 1-500 microM can be determined 'on line' by using 5 microliters of bile without sample pretreatment; bilirubin conjugates can be obtained preparatively in milligram quantities without degradation or contamination by other components of bile. H.p.l.c. analyses of a series of mammalian biles show that biliary UCB concentrations generally range from 1 to 17 microM. These values are considerably lower than those estimated previously by t.l.c. BMG is the predominant, if not exclusive, bilirubin conjugate in the biles of a number of rodents (guinea pig, hamster, mouse, prairie dog) that are experimental models of both pigment and cholesterol gallstone formation. Conjugated bilirubins in the biles of other animals (human, monkey, pony, cat, rat and dog) are chemically more diverse and include mono-, di- and mixed disconjugates of glucuronic acid, xylose and glucose in proportions that give distinct patterns for each species. PMID:3919713

Spivak, W; Carey, M C

1985-02-01

193

Reverse-phase h.p.l.c. separation, quantification and preparation of bilirubin and its conjugates from native bile. Quantitative analysis of the intact tetrapyrroles based on h.p.l.c. of their ethyl anthranilate azo derivatives.  

PubMed Central

We describe a facile and sensitive reverse-phase h.p.l.c. method for analytical separation of biliary bile pigments and direct quantification of unconjugated bilirubin (UCB) and its monoglucuronide (BMG) and diglucuronide (BDG) conjugates in bile. The method can be 'scaled up' for preparative isolation of pure BDG and BMG from pigment-enriched biles. We employed an Altex ultrasphere ODS column in the preparative steps and a Waters mu-Bondapak C18 column in the separatory and analytical procedures. Bile pigments were eluted with ammonium acetate buffer, pH 4.5, and a 20 min linear gradient of 60-100% (v/v) methanol at a flow rate of 2.0 ml/min for the preparative separations and 1.0 ml/min for the analytical separations. Bile pigments were eluted in order of decreasing polarity (glucuronide greater than glucose greater than xylose conjugates greater than UCB) and were chemically identified by t.l.c. of their respective ethyl anthranilate azo derivatives. Quantification of UCB was carried out by using a standard curve relating a range of h.p.l.c. integrated peak areas to concentrations of pure crystalline UCB. A pure crystalline ethyl anthranilate azo derivative of UCB (AZO . UCB) was employed as a single h.p.l.c. reference standard for quantification of BMG and BDG. We demonstrate that: separation and quantification of biliary bile pigments are rapid (approximately 25 min); bile pigment concentrations ranging from 1-500 microM can be determined 'on line' by using 5 microliters of bile without sample pretreatment; bilirubin conjugates can be obtained preparatively in milligram quantities without degradation or contamination by other components of bile. H.p.l.c. analyses of a series of mammalian biles show that biliary UCB concentrations generally range from 1 to 17 microM. These values are considerably lower than those estimated previously by t.l.c. BMG is the predominant, if not exclusive, bilirubin conjugate in the biles of a number of rodents (guinea pig, hamster, mouse, prairie dog) that are experimental models of both pigment and cholesterol gallstone formation. Conjugated bilirubins in the biles of other animals (human, monkey, pony, cat, rat and dog) are chemically more diverse and include mono-, di- and mixed disconjugates of glucuronic acid, xylose and glucose in proportions that give distinct patterns for each species. PMID:3919713

Spivak, W; Carey, M C

1985-01-01

194

IDENTIFICATION OF TWO GLUCURONIDE METABOLITES OF DOXYLAMINE VIA THERMOSPRAY/MASS SPECTROMETRY AND THERMOSPRAY/MASS SPECTROMETRY/MASS SPECTROMETRY  

EPA Science Inventory

Analysis of a high-pressure liquid chromatography fraction containing two urinary glucuronide metabolites of doxylamine by thermospray mass spectrometry (TSP/MS) provided (MH)+ ions for each metabolite. TSP/MS/MS of the (MH)+ ions provided a fragment ion characteristic of these m...

195

Human and Rat ABC Transporter Efflux of Bisphenol A and Bisphenol A Glucuronide: Interspecies Comparison and Implications for Pharmacokinetic Assessment  

EPA Science Inventory

Significant interspecies differences exist between human and rodent with respect to absorption, distribution, and excretion of bisphenol A (BPA) and its primary metabolite, BPA-glucuronide (BPA-G). ATP-Binding Cassette (ABC) transporter enzymes play important roles in these physi...

196

RELATIONSHIP BETWEEN HEPATIC MICROSOMAL THYROXINE GLUCURONIDATION AND TOTAL SERUM THYROXINE CONCENTRATIONS IN RATS TREATED WITH PCDDS, PCDFS AND PCBS  

EPA Science Inventory

RELATIONSHIP BETWEEN HEPATIC MICROSOMAL THYROXINE GLUCURONIDATION AND TOTAL SERUM THYROXINE CONCENTRATIONS IN RATS TREATED WITH PCDDs, PCDFs AND PCBs. D G Ross, K M Crofton, M J DeVito, NHEERL, ORD, USEPA, RTP, NC. Many PHAHs decrease thyroxine (T4), possibly due to inducti...

197

Isolation and characterization of carbinolamide and phenolic glucuronide conjugates of (+-)-N-methyl-N-(1-methyl-3,3-diphenylpropyl) formamide and N-formylmethamphetamine by FAB/MS, LC/MS/MS, and NMR.  

PubMed

The metabolic disposition of (+-)-N-methyl-N-(1-methyl-3,3- diphenyl-propyl)formamide, especially with regard to the formation of water soluble glucuronides, is described. The glucuronide conjugates, (+-)-N-hydroxymethyl-N-(1-methyl-3,3-diphenylpropyl)formamide glucuronide, (+-)-N-methyl-N-[1-methyl-3-(4'-hydroxyphenyl)-3-phenylpropyl]formamide glucuronide, and (+-)-N-methyl-N-[1-methyl-3-(4'-hydroxy-3'-methoxyphenyl)-3- phenylpropyl]formamide glucuronide were isolated from the bile of rats dosed with the parent compound. These conjugates were characterized spectroscopically by 1H-NMR, FAB/MS, and LC/MS/MS. Because it is becoming more common to isolate the intact glucuronide conjugates of xenobiotics, we investigated some common mass spectral fragmentation patterns of these conjugates, especially by LC/MS/MS. The fragmentation patterns for each of the conjugates were obtained under MS/MS conditions and compared. Specifically, the fragmentation patterns of phenolic glucuronide and an aliphatic O-glucuronide, in particular a carbinolamide glucuronide, were investigated. The data obtained from these studies was used to predict the nature of glucuronide conjugates obtained from rats dosed with the formamide analog, N-formylmethamphetamine. This is the first spectroscopic characterization of an intact carbinolamide glucuronide conjugate isolated from the bile of rats. PMID:1355723

Mutlib, A E; Abbott, F S

1992-01-01

198

Manufacturing Ethyl Acetate From Fermentation Ethanol  

NASA Technical Reports Server (NTRS)

Conceptual process uses dilute product of fermentation instead of concentrated ethanol. Low-concentration ethanol, extracted by vacuum from fermentation tank, and acetic acid constitutes feedstock for catalytic reaction. Product of reaction goes through steps that increases ethyl acetate content to 93 percent by weight. To conserve energy, heat exchangers recycle waste heat to preheat process streams at various points.

Rohatgi, Naresh K.; Ingham, John D.

1991-01-01

199

The effect of quercetin and kaempferol aglycones and glucuronides on peroxisome proliferator-activated receptor-gamma (PPAR-?).  

PubMed

The consumption of dietary flavonoids has been associated with a variety of health benefits, including effects mediated by the activation of peroxisome proliferator-activated receptor-gamma (PPAR-?). Flavonoids are extensively metabolized during and after uptake and there is little known on the biological effects of these conjugated metabolites of flavonoids that are found in plasma. To investigate the effect of glucuronidation on the ability of flavonoids to activate PPAR-? we studied and compared the activity of quercetin, kaempferol and their relevant plasma conjugates quercetin-3-O-glucuronide (Q3G) and kaempferol-3-O-glucuronide (K3G) on different PPAR-? related endpoints. The flavonoid aglycones increased PPAR-? mediated gene expression in a stably transfected reporter gene cell line and glucuronidation diminished their effect. To study the intrinsic activity of the test compounds to activate PPAR-? we used a novel microarray technique to study ligand induced ligand binding domain (LBD) - nuclear receptor coregulator interactions. In this cell-free system we demonstrate that, unlike the known PPAR-? agonist rosiglitazone, neither the flavonoid aglycones nor the conjugates are agonistic ligands of the receptor. The increases in reporter gene expression in the reporter cells were accompanied by increased PPAR-? receptor-mRNA expression and quercetin synergistically increased the effect of rosiglitazone in the reporter gene assay. It is concluded that flavonoids affect PPAR-? mediated gene transcription by a mode of action different from agonist binding. Increases in PPAR-? receptor mRNA expression and synergistic effects with endogenous PPAR-? agonists may play a role in this alternative mode of action. Glucuronidation reduced the activity of the flavonoid aglycones. PMID:25765892

Beekmann, Karsten; Rubió, Laura; de Haan, Laura H J; Actis-Goretta, Lucas; van der Burg, Bart; van Bladeren, Peter J; Rietjens, Ivonne M C M

2015-04-01

200

Quantitative Profiling of Human Renal UDP-glucuronosyltransferases and Glucuronidation Activity: A Comparison of Normal and Tumoral Kidney Tissues.  

PubMed

Renal metabolism by UDP-glucuronosyltransferase (UGT) enzymes is central to the clearance of many drugs. However, significant discrepancies about the relative abundance and activity of individual UGT enzymes in the normal kidney prevail among reports, whereas glucuronidation in tumoral kidney has not been examined. In this study, we performed an extensive profiling of glucuronidation metabolism in normal (n = 12) and tumor (n = 14) kidneys using targeted mass spectrometry quantification of human UGTs. We then correlated UGT protein concentrations with mRNA levels assessed by quantitative polymerase chain reaction and with conjugation activity for the major renal UGTs. Beyond the wide interindividual variability in expression levels observed among kidney samples, UGT1A9, UGT2B7, and UGT1A6 are the most abundant renal UGTs in both normal and tumoral tissues based on protein quantification. In normal kidney tissues, only UGT1A9 protein levels correlated with mRNA levels, whereas UGT1A6, UGT1A9, and UGT2B7 quantification correlated significantly with their mRNA levels in tumor kidneys. Data support that posttranscriptional regulation of UGT2B7 and UGT1A6 expression is modulating glucuronidation in the kidney. Importantly, our study reveals a significant decreased glucuronidation capacity of neoplastic kidneys versus normal kidneys that is paralleled by drastically reduced UGT1A9 and UGT2B7 mRNA and protein expression. UGT2B7 activity is the most repressed in tumors relative to normal tissues, with a 96-fold decrease in zidovudine metabolism, whereas propofol and sorafenib glucuronidation is decreased by 7.6- and 5.2-fold, respectively. Findings demonstrate that renal drug metabolism is predominantly mediated by UGT1A9 and UGT2B7 and is greatly reduced in kidney tumors. PMID:25650382

Margaillan, Guillaume; Rouleau, Michèle; Fallon, John K; Caron, Patrick; Villeneuve, Lyne; Turcotte, Véronique; Smith, Philip C; Joy, Melanie S; Guillemette, Chantal

2015-04-01

201

Analysis of R- and S-Hydroxywarfarin Glucuronidation Catalyzed by Human Liver Microsomes and Recombinant UDP-Glucuronosyltransferases  

PubMed Central

Coumadin (R-, S-warfarin) is a challenging drug to accurately dose, both initially and for maintenance, because of its narrow therapeutic range and wide interpatient variability and is typically administered as a racemic (Rac) mixture, which complicates the biotransformation pathways. The goal of the current work was to identify the human UDP-glucuronosyltransferases (UGTs) involved in the glucuronidation of the separated R- and S-enantiomers of 6-, 7-, and 8-hydroxywarfarin and the possible interactions between these enantiomers. The kinetic and inhibition constants for human recombinant 1A family UGTs toward these separated enantiomers have been assessed using high-performance liquid chromatography (HPLC)-UV-visible analysis, and product confirmations have been made using HPLC-mass spectrometry/mass spectrometry. We found that separated R- and S-enantiomers of 6-, 7-, and 8-hydroxywarfarin demonstrate significantly different glucuronidation kinetics and can be mutually inhibitory. In some cases significant substrate inhibition was observed, as shown by Km, Vmax, and Ki, comparisons. In particular, UGT1A1 and extrahepatic UGT1A10 have significantly higher capacities than other isoforms for S-7-hydroxywarfarin and R-7-hydroxywarfarin glucuronidation, respectively. Activity data generated using a set of well characterized human liver microsomes supported the recombinant enzyme data, suggesting an important (although not exclusive) role for UGT1A1 in glucuronidation of the main warfarin metabolites, including Rac-6- and 7-hydroxywarfarin and their R- and S-enantiomers in the liver. This is the first demonstration that the R- and S-enantiomers of hydroxywarfarins are glucuronidated, with significantly different enzymatic affinity and capacity, and supports the importance of UGT1A1 as the major hepatic isoform involved. PMID:21972237

Bratton, Stacie M.; Mosher, Carrie M.; Khallouki, Farid; Finel, Moshe; Court, Michael H.; Moran, Jeffery H.

2012-01-01

202

40 CFR 180.429 - Chlorimuron ethyl; tolerances for residues.  

Code of Federal Regulations, 2011 CFR

...180.429 Chlorimuron ethyl; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide chlorimuron ethyl, including its metabolites and degradates, in or on the commodities in the table below....

2011-07-01

203

40 CFR 180.429 - Chlorimuron ethyl; tolerances for residues.  

Code of Federal Regulations, 2014 CFR

...180.429 Chlorimuron ethyl; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide chlorimuron ethyl, including its metabolites and degradates, in or on the commodities in the table below....

2014-07-01

204

Antihyperglycemic effect of Hypericum perforatum ethyl acetate extract on streptozotocin-induced diabetic rats  

PubMed Central

Objective To evaluate the antihyperglycemic activity of ethyl acetate extract of Hypericum perforatum (H. perforatum) in streptozotocin (STZ)-induced diabetic rats. Methods Acute toxicity and oral glucose tolerance test were performed in normal rats. Male albino rats were rendered diabetic by STZ (40 mg/kg, intraperitoneally). H. perforatum ethyl acetate extract was orally administered to diabetic rats at 50, 100 and 200 mg/kg doses for 15 days to determine the antihyperglycemic activity. Biochemical parameters were determined at the end of the treatment. Results H. perforatum ethyl acetate extract showed dose dependant fall in fasting blood glucose (FBG). After 30 min of extract administration, FBG was reduced significantly when compared with normal rats. H. perforatum ethyl acetate extract produced significant reduction in plasma glucose level, serum total cholesterol, triglycerides, glucose-6-phosphatase levels. Tissue glycogen content, HDL-cholesterol, glucose-6-phosphate dehydrogenase were significantly increased compared with diabetic control. No death or lethal effect was observed in the toxic study. Conclusions The results demonstrate that H. perforatum ethyl acetate extract possesses potent antihyperglycemic activity in STZ induced diabetic rats. PMID:23569798

Arokiyaraj, S; Balamurugan, R; Augustian, P

2011-01-01

205

Surface-initiated ATRP of 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate on Phynox  

Microsoft Academic Search

Phynox is of high interest for technological applications due to its high corrosion resistance, mechanical properties and biocompatibility. In combination with these remarkable characteristics, some Phynox applications require specific surface properties that can be imparted with suitable surface functionalizations of the oxide layer. The present work aims at studying the surface-initiated atom transfer radical polymerization (ATRP) of 2-(methacryloyloxy)ethyl 2-(trimethylammonio)ethyl phosphate

Bastien Barthélémy; Sébastien Devillers; Isabelle Minet; Joseph Delhalle; Zineb Mekhalif

2011-01-01

206

Biosynthesis of ethyl caproate and other short ethyl esters catalyzed by cutinase in organic solvent  

Microsoft Academic Search

The main objective of this work was to study the enzymatic synthesis of short chain ethyl esters, a group of relevant aroma molecules, by Fusarium solani pisi cutinase in an organic solvent media (iso-octane), and to assess the influence of different parameters on the reaction yield.Cutinase displayed high initial esterification rates in iso-octane, which amounted to 1.15?molmin?1mg?1 for ethyl butyrate

Dragana P. C. de Barros; Luís P. Fonseca; P. Fernandes; Joaquim M. S. Cabral; Ljiljana Mojovic

2009-01-01

207

Quercetin-3-O-glucuronide induces ABCA1 expression by LXR? activation in murine macrophages.  

PubMed

Reverse cholesterol transport (RCT) removes excess cholesterol from macrophages to prevent atherosclerosis. ATP-binding cassette, subfamily A, member 1 (ABCA1) is a crucial cholesterol transporter involved in RCT to produce high density lipoprotein-cholesterol (HDLC), and is transcriptionally regulated by liver X receptor alpha (LXR?), a nuclear receptor. Quercetin is a widely distributed flavonoid in edible plants which prevented atherosclerosis in an animal model. We found that quercetin-3-O-glucuronide (Q3GA), a major quercetin metabolite after absorption from the digestive tract, enhanced ABCA1 expression, in vitro, via LXR? in macrophages. In addition, leaf extracts of a traditional Asian edible plant, Nelumbo nucifera (NNE), which contained abundant amounts of quercetin glycosides, significantly elevated plasma HDLC in mice. We are the first to present experimental evidence that Q3GA induced ABCA1 in macrophages, and to provide an alternative explanation to previous studies on arteriosclerosis prevention by quercetin. PMID:24216107

Ohara, Kazuaki; Wakabayashi, Hideyuki; Taniguchi, Yoshimasa; Shindo, Kazutoshi; Yajima, Hiroaki; Yoshida, Aruto

2013-11-29

208

21 CFR 172.872 - Methyl ethyl cellulose.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Methyl ethyl cellulose. 172.872 Section 172.872 Food...Multipurpose Additives § 172.872 Methyl ethyl cellulose. The food additive methyl ethyl cellulose may be safely used in food in...

2011-04-01

209

21 CFR 172.872 - Methyl ethyl cellulose.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 2009-04-01 true Methyl ethyl cellulose. 172.872 Section 172.872 Food...Multipurpose Additives § 172.872 Methyl ethyl cellulose. The food additive methyl ethyl cellulose may be safely used in food in...

2010-04-01

210

Rapid and simple method to determine morphine and its metabolites in rat plasma by liquid chromatography–mass spectrometry  

Microsoft Academic Search

A rapid and simple method for the determination of morphine (M), normorphine (NM), morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) in plasma by high-performance liquid chromatographic separation with mass spectrometric detection (HPLC–MS) has been developed. Samples (40 ?l) were cleaned-up by protein precipitation with two volumes (80 ?l) of acetonitrile and reconstituted in formic acid 0.1% in water. Naloxone was used as

Denis Projean; Julie Ducharme

2003-01-01

211

40 CFR 180.430 - Fenoxaprop-ethyl; tolerances for residues.  

Code of Federal Regulations, 2010 CFR

...Tolerances are established for the combined residues of the herbicide fenoxaprop-ethyl [(±)-ethyl 2-[4-[(6-chloro-2-benzoxazolyl...Time-limited tolerances are established for combined residues of the herbicide fenoxaprop-ethyl, [(±)-ethyl...

2010-07-01

212

Skin of the male African catfish, Clarias gariepinus: a source of steroid glucuronides  

SciTech Connect

Steroid metabolism in the skin of mature male African catfish, Clarias gariepinus, reared in the laboratory, was studied in vitro by tissue incubations with (/sup 3/H)pregnenolone, (/sup 3/H)dehydroepiandrosterone, (/sup 3/H)17 alpha-hydroxyprogesterone, (/sup 3/H)androstenedione, (/sup 14/C)11 beta-hydroxyandrostenedione, and (/sup 3/H)testosterone as precursors. While pregnenolone was not converted to any other steroid, dehydroepiandrosterone was transformed mainly to 5-androstene-3 beta, 17 beta-diol. The products of 17 alpha-hydroxyprogesterone incubations were 5 beta-pregnane-3 alpha,17 alpha-diol-20-one, 5 beta-pregnane-3 alpha,17 alpha, 20 beta-triol, and 5 beta-pregnan-17 alpha-o1-3,20-dione. The major steroids of androstenedione incubations were etiocholanolone, testosterone, and androsterone. Testosterone was converted mainly to etiocholanolone and androstenedione, and only small quantities of 11 beta-hydroxytestosterone, 11-ketotestosterone, and 11-ketoandrostenedione were the metabolites found in 11 beta-hydroxyandrostenedione incubation. These results demonstrated the presence of the enzymes 5 alpha- and 5 beta-reductases and 3 alpha-, 11 beta-, 17 beta-, and 20 beta-hydroxysteroid dehydrogenases in the skin. From enzymehistochemical results it appeared that the steroid conversions take place in the epithelial cells. Moreover, the presence of UDP-glucose dehydrogenase, an enzyme involved in the synthesis of glucuronic acid, in these cells indicates the possibility of steroid glucuronide formation. Indeed significant amounts of water-soluble steroid conjugates, particularly 5 beta-dihydrotestosterone- and testosterone-glucuronide, were found in the incubations with androstenedione and testosterone, indicating the presence of the UDP-glucuronosyl transferase in the catfish skin.

Ali, S.A.; Schoonen, W.G.; Lambert, J.G.; Van den Hurk, R.; Van Oordt, P.G.

1987-06-01

213

Specific localization of quercetin-3-O-glucuronide in human brain.  

PubMed

In recent years, many papers have suggested that dietary flavonoids may exert beneficial effects in the brain tissue for the protection of neurons against oxidative stress and inflammation. However, the bioavailability of flavonoids across the blood-brain barrier and the localization in the brain remain controversial. Thus, we examined the localization of quercetin-3-O-glucuronide (Q3GA), a major phase-II metabolite of quercetin, in the human brain tissues with or without cerebral infarction by immunohistochemical staining using anti-Q3GA antibody. A significant immunoreactivity was observed in the epithelial cells of the choroid plexus, which constitute the structural basis of the blood-cerebrospinal fluid (CSF) barrier, and in the foamy macrophages of recent infarcts. The cellular accumulation of Q3GA was also reproduced in vitro in macrophage-like RAW264, microglial MG6, and brain capillary endothelial RBEC1. It is of interest that a common feature of these cell lines is the deconjugation of Q3GA, resulting in the cellular accumulation of non-conjugated quercetin and the methylated forms. We then examined the anti-inflammatory activity of Q3GA and the deconjugated forms in the lipopolysaccharide-stimulated macrophage cells and revealed that the deconjugated forms (quercetin and a methylated form isorhamnetin), but not Q3GA itself, exhibited inhibitory effects on the inflammatory responses through attenuation of the c-Jun N-terminal kinase pathway. These results suggested that a quercetin glucuronide can pass through the blood-brain barrier, perhaps the CSF barrier, accumulate in specific types of cells, such as macrophages, and act as anti-inflammatory agents in the brain through deconjugation into the bioactive non-conjugated forms. PMID:24893148

Ishisaka, Akari; Mukai, Rie; Terao, Junji; Shibata, Noriyuki; Kawai, Yoshichika

2014-09-01

214

Fatty acid ethyl esters are present in human serum after ethanol ingestion  

Microsoft Academic Search

The aim of the study was to determine whether fatty acid ethyl esters, nonoxidative products of ethanol metabolism selectively present in organs damaged by ethanol abuse, are de- tectable in the serum after ethanol ingestion. Serum samples of hospital emergency room patients with positive (n = 32) and negative (n = 5) blood ethanol levels were assayed for fatty acid

Kathleen M. Doyle; David A. Bird; Salih Al-Salihi; Youseff Hallaq; Joanne E. Cluette-Brown; Kendrick A. Goss; Michael Laposata

215

Deuterium Exchange in Ethyl Acetoacetate: An Undergraduate GC-MS [Gas Chromatography-Mass Spectroscopy] Experiment  

ERIC Educational Resources Information Center

The role of ethanol O-d in nullifying the deuterolysis may be demonstrated by determining that transesterification of methyl acetoacetate of the ethyl ester occurs as well as deuterium exchange of the five acetoacetate hydrogens. The significant acidity of the methylene protons in the acetoacetate group, the efficacy of base catalysis, the role of…

Heinson, C. D.; Williams, J. M.; Tinnerman, W. N.; Malloy, T. B.

2005-01-01

216

Mycophenolic acid (MPA) and its glucuronide metabolites interact with transport systems responsible for excretion of organic anions in the basolateral membrane of the human kidney  

Microsoft Academic Search

Background. Mycophenolic acid (MPA), the active moiety of the prodrug mycophenolate mofetil, is widely used in immunosuppressive regimens after kidney, liver or heart transplantation. MPA is metab- olized predominantly to the inactive 7-O-glucuronide (MPAG). A minor fraction is converted to the phar- macologically active acyl glucuronide (AcMPAG). All compounds ultimately are eliminated via the kidneys. Due to their structures, MPA

Natascha A. Wolff; Birgitta C. Burckhardt; Gerhard Burckhardt; Michael Oellerich; Victor W. Armstrong

217

A validated hybrid quadrupole linear ion-trap LC–MS method for the analysis of morphine and morphine glucuronides applied to opiate deaths  

Microsoft Academic Search

A hybrid quadrupole linear ion-trap mass spectrometer using an electrospray ionisation ion source coupled to a HPLC system has been used to develop a method which can accurately measure morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) in plasma, whole blood and post-mortem blood following solid-phase extraction. The method can also qualitatively detect various other opioids and related compounds including: codeine, dihydrocodeine

Kerry Taylor; Simon Elliott

2009-01-01

218

In situ ethylation–purge and programmed-temperature-vaporizer cold trapping–gas chromatography–mass spectrometry as an automated technique for the determination of methyl- and butyltin compounds in aqueous samples  

Microsoft Academic Search

A new method for the determination of methyl- and butyltin compounds in aqueous samples is presented. The organotin species are derivatized in situ with sodium tetraethylborate (NaBEt4) in an 800-ml sample, purged on-line with helium and cryofocused at ?40°C in the Tenax-filled glass insert of a modified split\\/splitless injector. The injector is equipped with a liquid nitrogen cooling and a

Ralf Eiden; Heinz Friedrich Schöler; Manfred Gastner

1998-01-01

219

Transesterification process to manufacture ethyl ester of rape oil  

SciTech Connect

A process for the production of the ethyl ester of winter rape [EEWR] for use as a biodiesel fuel has been studied. The essential part of the process is the transesterification of rape oil with ethanol, in the presence of a catalyst, to yield the ethyl ester of rape oil as a product and glycerin as a by-product. Experiments have been performed to determine the optimum conditions for the preparation of EEWR. The process variables were: (1) temperature, (2) catalyst, (3) rate of agitation, (4) water content of the alcohol used, and (5) the amount of excess alcohol used. The optimum conditions were: (1) room temperature, (2) 0.5% sodium methoxide or 1% potassium hydroxide catalyst by weight of rapeseed oil, (3) extremely vigorous agitation with some splashing during the initial phase of the reaction and agitation was not necessary after the reaction mixture became homogeneous, (4) absolute ethanol was necessary for high conversion, and (5) 50% excess ethanol with NaOCH{sub 3} or 100% excess with KOH gave a maximum conversion. Viscosity, cloud point and pour point of the EEWR were measured. A preliminary break-even cost for the commercial production of EEWR was found to be $0.55/liter [$2.08/US gallon].

Korus, R.A.; Hoffman, D.S.; Bam, N.; Peterson, C.L.; Drown, D.C. [Univ. of Idaho, Moscow, ID (United States)

1993-12-31

220

Structure-activity relationship (SAR): effort towards blocking N-glucuronidation of indazoles (PF-03376056) by human UGT1A enzymes.  

PubMed

GyrATPase is a cellular enzyme that has been used as an antibacterial target for treatment of nosocomial and community acquired bacterial infections. The leading chemical series targeted at inhibiting this enzyme, indazoles, were rapidly cleared in rats (CL > 70 mL/min/kg). The predominant metabolite identified in both urine and bile samples from a bile duct-cannulated study corresponded to direct glucuronidation of the parent compound and was excreted rapidly. Subsequently, a carefully designed analog was used to pinpoint the site of glucuronidation (N-glucuronidation) by incubation with rat hepatocytes and followed by mass spectrometry analysis. Reaction mapping with an array of recombinant UGT isozymes revealed that N-glucuronidation was predominantly catalyzed by the UGT1A family of enzymes. Based on the results, the following approaches were considered to reduce or eliminate glucuronidation: 1) adding sterically hindered substitutions on the phenyl ring of the indazole core; 2) changing the electron distribution by substituting with electron-donating or -withdrawing groups; 3) replacing the site of glucuronidation. The resulted compounds were evaluated in vitro in rat hepatocytes to assess their metabolic stabilities followed by in vivo efficacy studies in the murine peritonitis sepsis model (at 50 mg/kg) for selected compounds. PMID:19356114

Rose, Kelly; Yang, Young-Sun; Sciotti, Richard; Cai, Hongliang

2009-01-01

221

Identification and determination of carboxylic acids in food samples using 2-(2-(anthracen-10-yl)-1H-phenanthro[9,10-d]imidazol-1-yl)ethyl 4-methylbenzenesulfonate (APIETS) as labeling reagent by HPLC with FLD and APCI/MS.  

PubMed

A new labeling reagent for carboxylic acids, 2-(2-(anthracen-10-yl)-1H-phenanthro[9,10-d]imidazol-1-yl)ethyl 4-methylbenzenesulfonate (APIETS) has been designed and synthesized. It was used to label eight fatty acids (lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, oleic acid, linoleic acid and linolenic acid) and four hydroxy pentacyclic triterpene acids (oleanolic acid, ursolic acid, betulinic acid and maslinic acid), successfully. APIETS could easily and quickly label carboxylic acids in the presence of K(2)CO(3) catalyst at 85°C for 35 min in N,N-dimethylformamide solvent. The carboxylic acids derivatives were separated on a C(8) reversed-phase column with gradient elution and fluorescence detection at ?(ex)/?(em)=315/435 nm. Identification of these derivatives was carried out by online mass spectrometry with atmospheric pressure chemical ionization in positive ion mode. The detection limits obtained were 13.37-30.26fmol (signal-to-noise ratio of 3). The proposed method has been applied to the quantification of carboxylic acids in sultana raisin (Thompson seedless), hawthorn flake (Crataegus pinnatifida Bge.), Lycium barbarum seed oil and Microula sikkimensis seed oil with recoveries over 95.3%. It has been demonstrated that APIETS is a prominent labeling reagent for determining carboxylic acids with high performance liquid chromatography. PMID:21726743

Sun, Zhiwei; You, Jinmao; Song, Cuihua; Xia, Lian

2011-08-15

222

Glucuronidation of the red clover isoflavone irilone by liver microsomes from different species and human UDP-glucuronosyltransferases.  

PubMed

Red clover (Trifolium pratense L.) is used as a source for isoflavone (IF) dietary supplements. In this study, we focused on the red clover IF irilone (IRI), because of its reported comparatively high bioavailability. Because the conjugative metabolism plays a key role in the elimination of IF, we investigated the species-specific differences and glucuronidation kinetics of IRI using different liver microsomes as well as the recombinant UDP-glucuronosyltransferases (UGTs) 1A1, 1A7, 1A8, 1A9, 1A10, and 2B15. Both possible monoglucuronides, the IRI-O-4'-monoglucuronide (IRI-G4') and the IRI-O-5-monoglucuronide (IRI-G5), were detected. Human liver microsomes (HLM) as well as rat liver microsomes predominantly formed IRI-G5, whereas for porcine liver microsomes, IRI-G4' prevailed. HLM showed an apparent V(max) value of 0.43 nmol/min · mg and an apparent K(m) value of 9.8 ?M for the formation of IRI-G5 and a V(max) of 0.35 nmol/min · mg and a K(m) of 64.7 ?M in the case of IRI-G4'. Formation of both glucuronides was best fit using the substrate inhibition equation. The glucuronidation of IRI by UGTs led to values for the intrinsic clearance varying between 4 and 100 ml/min · mg, with UGT1A7 showing the lowest and UGT1A10 the highest IRI conversion rate. The results indicate that IRI undergoes an efficient glucuronidation, presumably in the intestine and liver, following atypical kinetic profiles. PMID:21177485

Maul, Ronald; Siegl, Diana; Kulling, Sabine E

2011-04-01

223

Species difference in the inhibitory potentials of non-steroidal anti-inflammatory drugs on the hepatic sulfation and glucuronidation of bioactive flavonoids: differential observations among common inhibition parameters.  

PubMed

1. This study elucidated the species differences between rats and humans in the inhibitory potential of drugs against sulfation and glucuronidation, and whether such differences depend on the inhibition parameter adopted. 2. With 14 non-steroidal anti-inflammatory drugs (NSAIDs) as model inhibitors and three flavanoids baicalein, wogonin and oroxylin A as model substrates, three common inhibition parameters percentage of control, IC50 and Ki were determined in rat liver cytosols (RLCs), human liver cytosols (HLCs), rat liver microsomes (RLMs) and human liver microsomes (HLMs). The closeness of the inhibition parameters from rat liver preparations to that from human liver preparations was analyzed by geometric mean fold error (GMFE) and statistical comparisons. 3. The percentage of control in RLC/RLM was not significantly different from that in HLC/HLM, with a GMFE of 0.85 (RLC-HLC) and 1.03 (RLM-HLM); whereas the IC50 and Ki in RLC/RLM were significantly different from that in HLC/HLM. The trend of difference was consistent between IC50 and Ki, where these parameters in RLC and RLM underestimated (GMFE <0.5) and overestimated (GMFE >2) that in HLC and HLM, respectively. 4. In conclusion, the inhibitory potentials of NSAIDs against sulfation and glucuronidation in rats and humans were different and depended on the adopted inhibition parameters. PMID:24168065

Fong, Sophia Yui Kau; Zuo, Zhong

2014-05-01

224

Human ?/? Hydrolase Domain Containing 10 (ABHD10) Is Responsible Enzyme for Deglucuronidation of Mycophenolic Acid Acyl-glucuronide in Liver*  

PubMed Central

Mycophenolic acid (MPA), the active metabolite of the immunosuppressant mycophenolate mofetil (MMF), is primarily metabolized by glucuronidation to a phenolic glucuronide (MPAG) and an acyl glucuronide (AcMPAG). It is known that AcMPAG, which may be an immunotoxic metabolite, is deglucuronidated in human liver. However, it has been reported that recombinant ?-glucuronidase does not catalyze this reaction. AcMPAG deglucuronidation activity was detected in both human liver cytosol (HLC) and microsomes (HLM). In this study, the enzyme responsible for AcMPAG deglucuronidation was identified by purification from HLC with column chromatographic purification steps. The purified enzyme was identified as ?/? hydrolase domain containing 10 (ABHD10) by amino acid sequence analysis. Recombinant ABHD10 expressed in Sf9 cells efficiently deglucuronidated AcMPAG with a Km value of 100.7 ± 10.2 ?m, which was similar to those in HLM, HLC, and human liver homogenates (HLH). Immunoblot analysis revealed ABHD10 protein expression in both HLC and HLM. The AcMPAG deglucuronidation by recombinant ABHD10, HLC, and HLH were potently inhibited by AgNO3, CdCl2, CuCl2, PMSF, bis-p-nitrophenylphosphate, and DTNB. The CLint value of AcMPAG formation from MPA, which was catalyzed by human UGT2B7, in HLH was increased by 1.8-fold in the presence of PMSF. Thus, human ABHD10 would affect the formation of AcMPAG, the immunotoxic metabolite. PMID:22294686

Iwamura, Atsushi; Fukami, Tatsuki; Higuchi, Ryota; Nakajima, Miki; Yokoi, Tsuyoshi

2012-01-01

225

Isolation and characterization of a ?-glucuronide of hydroxylated SARM S1 produced using a combination of biotransformation and chemical oxidation.  

PubMed

In this study, using mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy, it has been confirmed that biotransformation with the fungus Cunninghamella elegans combined with chemical oxidation with the free radical tetramethylpiperidinyl-1-oxy (TEMPO) can produce drug glucuronides of ?-configuration. Glucuronic acid conjugates are a common type of metabolites formed by the human body. The detection of such conjugates in doping control and other kinds of forensic analysis would be beneficial owing to a decrease in analysis time as hydrolysis can be omitted. However the commercial availability of reference standards for drug glucuronides is poor. The selective androgen receptor modulator (SARM) SARM S1 was incubated with the fungus C. elegans. The sample was treated with the free radical TEMPO oxidizing agent and was thereafter purified by SPE. A glucuronic acid conjugate was isolated using a fraction collector connected to an ultra high performance liquid chromatographic (UHPLC) system. The isolated compound was characterized by NMR spectroscopy and mass spectrometry and its structure was confirmed as a glucuronic acid ?-conjugate of hydroxylated SARM S1 bearing the glucuronide moiety on carbon C-10. PMID:24879518

Rydevik, Axel; Lagojda, Andreas; Thevis, Mario; Bondesson, Ulf; Hedeland, Mikael

2014-09-01

226

Pallidol hexa­acetate ethyl acetate monosolvate  

PubMed Central

The entire mol­ecule of pallidol hexa­acetate {systematic name: (±)-(4bR,5R,9bR,10R)-5,10-bis­[4-(acet­yloxy)phen­yl]-4b,5,9b,10-tetra­hydro­indeno­[2,1-a]indene-1,3,6,8-tetrayl tetra­acetate} is completed by the application of twofold rotational symmetry in the title ethyl acetate solvate, C40H34O12·C4H8O2. The ethyl acetate mol­ecule was highly disordered and was treated with the SQUEEZE routine [Spek (2009 ?). Acta Cryst. D65, 148–155]; the crystallographic data take into account the presence of the solvent. In pallidol hexa­acetate, the dihedral angle between the fused five-membered rings (r.m.s. deviation = 0.100?Å) is 54.73?(6)°, indicating a significant fold in the mol­ecule. Significant twists between residues are also evident as seen in the dihedral angle of 80.70?(5)° between the five-membered ring and the pendent benzene ring to which it is attached. Similarly, the acetate residues are twisted with respect to the benzene ring to which they are attached [C—O(carb­oxy)—C—C torsion angles = ?70.24?(14), ?114.43?(10) and ?72.54?(13)°]. In the crystal, a three-dimensional architecture is sustained by C—H?O inter­actions which encompass channels in which the disordered ethyl acetate mol­ecules reside. PMID:24046702

Mao, Qinyong; Taylor, Dennis K.; Ng, Seik Weng; Tiekink, Edward R. T.

2013-01-01

227

Optimization of ethyl ester production assisted by ultrasonic irradiation.  

PubMed

This study presents the optimization of the continuous flow potassium hydroxide-catalyzed synthesis of ethyl ester from palm oil with ultrasonic assistance. The process was optimized by application of factorial design and response surface methodology. The independent variables considered were ethanol to oil molar ratio, catalyst concentration, reaction temperature and ultrasonic amplitude; and the response was ethyl ester yield. The results show that ethanol to oil molar ratio, catalyst concentration, and ultrasonic amplitude have positive effect on ethyl ester yield, whereas reaction temperature has negative influence on ethyl ester yield. Second-order models were developed to predict the responses analyzed as a function of these three variables, and the developed models predicts the results in the experimental ranges studied adequately. This study shows that ultrasonic irradiation improved the ethyl ester production process to achieve ethyl ester yields above 92%. PMID:25116594

Noipin, K; Kumar, S

2015-01-01

228

Identification of brain-targeted bioactive dietary quercetin-3-O-glucuronide as a novel intervention for Alzheimer's disease  

PubMed Central

Epidemiological and preclinical studies indicate that polyphenol intake from moderate consumption of red wines may lower the relative risk for developing Alzheimer's disease (AD) dementia. There is limited information regarding the specific biological activities and cellular and molecular mechanisms by which wine polyphenolic components might modulate AD. We assessed accumulations of polyphenols in the rat brain following oral dosage with a Cabernet Sauvignon red wine and tested brain-targeted polyphenols for potential beneficial AD disease-modifying activities. We identified accumulations of select polyphenolic metabolites in the brain. We demonstrated that, in comparison to vehicle-control treatment, one of the brain-targeted polyphenol metabolites, quercetin-3-O-glucuronide, significantly reduced the generation of ?-amyloid (A?) peptides by primary neuron cultures generated from the Tg2576 AD mouse model. Another brain-targeted metabolite, malvidin-3-O-glucoside, had no detectable effect on A? generation. Moreover, in an in vitro analysis using the photo-induced cross-linking of unmodified proteins (PICUP) technique, we found that quercetin-3-O-glucuronide is also capable of interfering with the initial protein-protein interaction of A?1–40 and A?1–42 that is necessary for the formation of neurotoxic oligomeric A? species. Lastly, we found that quercetin-3-O-glucuronide treatment, compared to vehicle-control treatment, significantly improved AD-type deficits in hippocampal formation basal synaptic transmission and long-term potentiation, possibly through mechanisms involving the activation of the c-Jun N-terminal kinases and the mitogen-activated protein kinase signaling pathways. Brain-targeted quercetin-3-O-glucuronide may simultaneously modulate multiple independent AD disease-modifying mechanisms and, as such, may contribute to the benefits of dietary supplementation with red wines as an effective intervention for AD.—Ho, L., Ferruzzi, M. G., Janle, E. M., Wang, J., Gong, B., Chen, T.-Y., Lobo, J., Cooper, B., Wu, Q. L., Talcott, S. T., Percival, S. S., Simon, J. E., Pasinetti, G. M. Identification of brain-targeted bioactive dietary quercetin-3-O-glucuronide as a novel intervention for Alzheimer's disease. PMID:23097297

Ho, Lap; Ferruzzi, Mario G.; Janle, Elsa M.; Wang, Jun; Gong, Bing; Chen, Tzu-Ying; Lobo, Jessica; Cooper, Bruce; Wu, Qing Li; Talcott, Stephen T.; Percival, Susan S.; Simon, James E.; Pasinetti, Giulio Maria

2013-01-01

229

Nasal administration of morphine-6-glucuronide in sheep--a pharmacokinetic study.  

PubMed

The pharmacokinetics of morphine-6-glucuronide (M6G) after both intravenous dosing and nasal administration were studied in sheep. The nasal formulation consisted of M6G in combination with an absorption promoting delivery system in the form of chitosan. The mean half-life of M6G after intravenous administration was 51.0 +/- 8.2 min and that after intranasal dosing was 45.0 +/- 5.5 min. M6G clearance and volume of distribution were 5.4 +/- 1.5 mL min-1 kg-1 and 0.4 +/- 0.1 L kg-1 respectively. The plasma profile after nasal administration demonstrated rapid absorption of M6G. The bioavailability of M6G in the chitosan formulation was found to be 31.4%. These results suggest that M6G administered in combination with the chitosan delivery system may be considered as a suitable non-parenteral means of administering this analgesic. PMID:8950049

Illum, L; Davis, S S; Pawula, M; Fisher, A N; Barrett, D A; Farraj, N F; Shaw, P N

1996-11-01

230

Quercetin-3-O-glucuronide induces ABCA1 expression by LXR? activation in murine macrophages  

SciTech Connect

Highlights: •The major circulating quercetin metabolite (Q3GA) activated LXR?. •Q3GA induced ABCA1 via LXR? activation in macrophages. •Nelumbo nucifera leaf extracts contained quercetin glycosides. •N. nucifera leaf extract feeding elevated HDLC in mice. -- Abstract: Reverse cholesterol transport (RCT) removes excess cholesterol from macrophages to prevent atherosclerosis. ATP-binding cassette, subfamily A, member 1 (ABCA1) is a crucial cholesterol transporter involved in RCT to produce high density lipoprotein-cholesterol (HDLC), and is transcriptionally regulated by liver X receptor alpha (LXR?), a nuclear receptor. Quercetin is a widely distributed flavonoid in edible plants which prevented atherosclerosis in an animal model. We found that quercetin-3-O-glucuronide (Q3GA), a major quercetin metabolite after absorption from the digestive tract, enhanced ABCA1 expression, in vitro, via LXR? in macrophages. In addition, leaf extracts of a traditional Asian edible plant, Nelumbo nucifera (NNE), which contained abundant amounts of quercetin glycosides, significantly elevated plasma HDLC in mice. We are the first to present experimental evidence that Q3GA induced ABCA1 in macrophages, and to provide an alternative explanation to previous studies on arteriosclerosis prevention by quercetin.

Ohara, Kazuaki, E-mail: Kazuaki_Ohara@kirin.co.jp [Research Laboratories for Health Science and Food Technologies, Kirin Company Limited, 1-13-5 Fukuura, Kanazawa-ku, Yokohama 236-0004 (Japan)] [Research Laboratories for Health Science and Food Technologies, Kirin Company Limited, 1-13-5 Fukuura, Kanazawa-ku, Yokohama 236-0004 (Japan); Wakabayashi, Hideyuki [Laboratory for New Product Development, Kirin Beverage Company Limited, 1-17-1 Namamugi, Tsurumi-ku, Yokohama 230-8628 (Japan)] [Laboratory for New Product Development, Kirin Beverage Company Limited, 1-17-1 Namamugi, Tsurumi-ku, Yokohama 230-8628 (Japan); Taniguchi, Yoshimasa [Research Laboratories for Health Science and Food Technologies, Kirin Company Limited, 1-13-5 Fukuura, Kanazawa-ku, Yokohama 236-0004 (Japan)] [Research Laboratories for Health Science and Food Technologies, Kirin Company Limited, 1-13-5 Fukuura, Kanazawa-ku, Yokohama 236-0004 (Japan); Shindo, Kazutoshi [Department of Food and Nutrition, Japan Women’s University, 2-8-1 Mejirodai, Bunkyo-ku, Tokyo 112-8681 (Japan)] [Department of Food and Nutrition, Japan Women’s University, 2-8-1 Mejirodai, Bunkyo-ku, Tokyo 112-8681 (Japan); Yajima, Hiroaki [Research Laboratories for Health Science and Food Technologies, Kirin Company Limited, 1-13-5 Fukuura, Kanazawa-ku, Yokohama 236-0004 (Japan)] [Research Laboratories for Health Science and Food Technologies, Kirin Company Limited, 1-13-5 Fukuura, Kanazawa-ku, Yokohama 236-0004 (Japan); Yoshida, Aruto [Central Laboratories for Key Technologies, Kirin Company Limited, 1-13-5 Fukuura, Kanazawa-ku, Yokohama 236-0004 (Japan)] [Central Laboratories for Key Technologies, Kirin Company Limited, 1-13-5 Fukuura, Kanazawa-ku, Yokohama 236-0004 (Japan)

2013-11-29

231

Interaction of Ethyl Alcohol Vapor with Sulfuric Acid Solutions  

NASA Technical Reports Server (NTRS)

We investigated the uptake of ethyl alcohol (ethanol) vapor by sulfuric acid solutions over the range approx.40 to approx.80 wt % H2SO4 and temperatures of 193-273 K. Laboratory studies used a fast flow-tube reactor coupled to an electron-impact ionization mass spectrometer for detection of ethanol and reaction products. The uptake coefficients ((gamma)) were measured and found to vary from 0.019 to 0.072, depending upon the acid composition and temperature. At concentrations greater than approx.70 wt % and in dilute solutions colder than 220 K, the values approached approx.0.07. We also determined the effective solubility constant of ethanol in approx.40 wt % H2SO4 in the temperature range 203-223 K. The potential implications to the budget of ethanol in the global troposphere are briefly discussed.

Leu, Ming-Taun

2006-01-01

232

Morphine glucuronidation and glucosidation represent complementary metabolic pathways that are both catalyzed by UDP-glucuronosyltransferase 2B7: kinetic, inhibition, and molecular modeling studies.  

PubMed

Morphine 3-?-D-glucuronide (M3G) and morphine 6-?-D-glucuronide (M6G) are the major metabolites of morphine in humans. More recently, morphine-3-?-d-glucoside (M-3-glucoside) was identified in the urine of patients treated with morphine. Kinetic and inhibition studies using human liver microsomes (HLM) and recombinant UGTs as enzyme sources along with molecular modeling were used here to characterize the relationship between morphine glucuronidation and glucosidation. The M3G to M6G intrinsic clearance (C(Lint)) ratio (?5.5) from HLM supplemented with UDP-glucuronic acid (UDP-GlcUA) alone was consistent with the relative formation of these metabolites in humans. The mean C(Lint) values observed for M-3-glucoside by incubations of HLM with UDP-glucose (UDP-Glc) as cofactor were approximately twice those for M6G formation. However, although the M3G-to-M6G C(Lint) ratio remained close to 5.5 when human liver microsomal kinetic studies were performed in the presence of a 1:1 mixture of cofactors, the mean C(Lint) value for M-3-glucoside formation was less than that of M6G. Studies with UGT enzyme-selective inhibitors and recombinant UGT enzymes, along with effects of BSA on morphine glycosidation kinetics, were consistent with a major role of UGT2B7 in both morphine glucuronidation and glucosidation. Molecular modeling identified key amino acids involved in the binding of UDP-GlcUA and UDP-Glc to UGT2B7. Mutagenesis of these residues abolished morphine glucuronidation and glucosidation. Overall, the data indicate that morphine glucuronidation and glucosidation occur as complementary metabolic pathways catalyzed by a common enzyme (UGT2B7). Glucuronidation is the dominant metabolic pathway because the binding affinity of UDP-GlcUA to UGT2B7 is higher than that of UDP-Glc. PMID:24459244

Chau, Nuy; Elliot, David J; Lewis, Benjamin C; Burns, Kushari; Johnston, Martin R; Mackenzie, Peter I; Miners, John O

2014-04-01

233

Phase II metabolism in human skin: skin explants show full coverage for glucuronidation, sulfation, N-acetylation, catechol methylation, and glutathione conjugation.  

PubMed

Although skin is the largest organ of the human body, cutaneous drug metabolism is often overlooked, and existing experimental models are insufficiently validated. This proof-of-concept study investigated phase II biotransformation of 11 test substrates in fresh full-thickness human skin explants, a model containing all skin cell types. Results show that skin explants have significant capacity for glucuronidation, sulfation, N-acetylation, catechol methylation, and glutathione conjugation. Novel skin metabolites were identified, including acyl glucuronides of indomethacin and diclofenac, glucuronides of 17?-estradiol, N-acetylprocainamide, and methoxy derivatives of 4-nitrocatechol and 2,3-dihydroxynaphthalene. Measured activities for 10 ?M substrate incubations spanned a 1000-fold: from the highest 4.758 pmol·mg skin(-1)·h(-1) for p-toluidine N-acetylation to the lowest 0.006 pmol·mg skin(-1)·h(-1) for 17?-estradiol 17-glucuronidation. Interindividual variability was 1.4- to 13.0-fold, the highest being 4-methylumbelliferone and diclofenac glucuronidation. Reaction rates were generally linear up to 4 hours, although 24-hour incubations enabled detection of metabolites in trace amounts. All reactions were unaffected by the inclusion of cosubstrates, and freezing of the fresh skin led to loss of glucuronidation activity. The predicted whole-skin intrinsic metabolic clearances were significantly lower compared with corresponding whole-liver intrinsic clearances, suggesting a relatively limited contribution of the skin to the body's total systemic phase II enzyme-mediated metabolic clearance. Nevertheless, the fresh full-thickness skin explants represent a suitable model to study cutaneous phase II metabolism not only in drug elimination but also in toxicity, as formation of acyl glucuronides and sulfate conjugates could play a role in skin adverse reactions. PMID:25339109

Manevski, Nenad; Swart, Piet; Balavenkatraman, Kamal Kumar; Bertschi, Barbara; Camenisch, Gian; Kretz, Olivier; Schiller, Hilmar; Walles, Markus; Ling, Barbara; Wettstein, Reto; Schaefer, Dirk J; Itin, Peter; Ashton-Chess, Joanna; Pognan, Francois; Wolf, Armin; Litherland, Karine

2015-01-01

234

Glucuronidation of the oxidative cytochrome P450-mediated phenolic metabolites of the endocrine disruptor pesticide: methoxychlor by human hepatic UDP-glucuronosyl transferases.  

PubMed

Methoxychlor, a currently used pesticide, is a proestrogen exhibiting estrogenic activity in mammals in vivo. Methoxychlor undergoes oxidative metabolism by cytochromes P450, yielding 1,1,1-trichloro-2-(4-hydroxyphenyl)-2-(4-methoxyphenyl)ethane (mono-OH-M) and 1,1,1-trichloro-2,2-bis(4-hydroxyphenyl)ethane (bis-OH-M) as main metabolites. Since humans may be exposed to these estrogenic metabolites, which are potential substrates of UDP-glucuronosyltransferases (UGTs), their glucuronide conjugation was investigated with human liver preparations and individual UGTs. Incubation of both mono-OH-M and bis-OH-M with human liver microsomes formed monoglucuronides. The structures of the glucuronides were identified by liquid chromatography/tandem mass spectometry. Examination of cDNA-expressed recombinant human hepatic UGTs revealed that several catalyze glucuronidation of both compounds. Among the cDNA-expressed UGT1A enzymes, UGT1A9 seemed to be the main catalyst of formation of mono-OH-M-glucuronide, whereas UGT1A3 seemed to be the most active in bis-OH-M-glucuronide formation. Furthermore, the chiral selectivity of mono-OH-M glucuronidation was examined. The results of the incubation of single enantiomers generally agreed with the chiral analyses of mono-OH-M derived from the glucuronidase digestion of the glucuronides of the racemic mono-OH-M. There was a relatively slight but consistent enantioselective preference of individual UGT1A1, UGT1A3, UGT1A9, and UGT2B15 enzymes for glucuronidation of the S- over the R-mono-OH-M, whereas in human liver microsomes differences were observed among donors in generating the respective R/S-mono-OH-M ratio. Since it was previously shown that human liver microsomes demethylate methoxychlor mainly into S-mono-OH-M, the observation that UGT1A isoforms preferentially glucuronidate the S-mono-OH-M suggests a suitable mechanism for eliminating this major enantiomer. This enantiomeric preference, however, is not extended to all samples of human liver microsomes that we tested. PMID:15205390

Hazai, Eszter; Gagne, Peter V; Kupfer, David

2004-07-01

235

Signal enhancement of glucuronide conjugates in LC-MS/MS by derivatization with the phosphonium propylamine cation tris(trimethoxyphenyl) phosphonium propylamine, for forensic purposes.  

PubMed

Although chemical derivatization for signal enhancement in drug testing is most often associated with gas chromatography, it also has the potential to improve the detection of analytes poorly ionized by atmospheric pressure ionization techniques, such as electrospray ionization used in liquid chromatography-mass spectrometry. A number of acidic compounds, namely drug glucuronides (e.g. conjugates of temazepam, oxazepam, lorazepam, morphine, testosterone, epitestosterone, 5-?-dihydrotestosterone, androsterone, p-nitrophenol, and paracetamol) were successfully derivatized with tris(trimethoxyphenyl) phosphoniumpropylamine to introduce a quaternary cation functionality to the analytes. Benzodiazepine glucuronides were more specifically investigated, and following positive mode electrospray ionization mass spectrometry, average improvements to peak areas as a result of derivatization were 67-, 6-, and 7- fold for temazepam, oxazepam, and lorazepam glucuronides. Average improvements to the signal-to-noise ratios for temazepam, oxazepam, and lorazepam glucuronides were 1336-, 371- and 217-fold, respectively. The values obtained for the derivatized conjugate were also typically higher than those for the underivatized parent drug. Urine containing benzodiazepine glucuronides was also successfully derivatized. The data indicates potential for the use of charge derivatization to improve the detection of molecules with acidic functionalities by liquid chromatography-mass spectrometry (LC-MS) techniques in certain scenarios. PMID:24753456

Turfus, Sophie C; Halket, John M; Parkin, Mark C; Cowan, David A; Braithwaite, Robin A; Kicman, Andrew T

2014-05-01

236

Ethyl acetate extract from black tea prevents neuromuscular blockade by botulinum neurotoxin type A in vitro.  

PubMed

Botulinum neurotoxin produced by Clostridium botulinum is the strongest neurotoxin and causes botulism in mammals. The current study aimed to find an inactivator for botulinum neurotoxin in black, oolong, roasted, and green teas. The ability of the four teas to inactivate the neuromuscular blocking action of botulinum neurotoxin was determined. Water extracts from black, oolong, and roasted teas protected against the toxicity of botulinum neurotoxin type A in mouse phrenic nerve-diaphragm preparations. The order of potency of the water extracts was black tea > oolong tea > roasted tea > green tea (no effect). The effects of several organic solvent extracts of black tea water extract were examined, and the order of potency was ethyl acetate extract > butanol extract = remaining extract > chloroform extract (no effect). Ethyl acetate extracts from oolong, roasted, and green tea water extracts also exhibited a stronger protecting effect than chloroform, butanol, and remaining extracts from these teas, but they had weaker protective effect than ethyl acetate extract from black tea water extract. These protective effects occurred only when each extract was pre-mixed with the toxin before the assay, and they were not modified by mixing each extract with bovine serum albumin (BSA) before adding the toxin. These results indicate that ethyl acetate extract from black tea is the best source for searching for tea-derived inactivating substance(s) of botulinum neurotoxin. PMID:16638658

Satoh, Eiki

2005-12-01

237

The effects of two internal rotations in the microwave spectrum of ethyl methyl ketone  

NASA Astrophysics Data System (ADS)

The rotational spectra of ethyl methyl ketone, CH3CH2COCH3, were measured in the microwave region from 2 to 40 GHz using two molecular beam Fourier transform microwave spectrometers. Splittings due to internal rotations of both, the acetyl methyl group -COCH3 and the ethyl methyl group CH3CH2CO-, could be completely resolved. All measured transitions were fitted using two different codes, XIAM and BELGI-Cs-2Tops. Molecular parameters like the rotational constants and the centrifugal distortion constants were determined with very high accuracy. The barrier to internal rotation of the acetyl methyl group was fitted to 181.502(98) cm-1, much lower than the value of 763.87(65) cm-1 found for the ethyl methyl group. The splittings in the spectrum due to internal rotation of the acetyl methyl group are accordingly much larger, up to 1.2 GHz, whereas for the ethyl methyl group only splittings from a few hundreds of kHz up to 4 MHz were observed.

Nguyen, Ha Vinh Lam; Van, Vinh; Stahl, Wolfgang; Kleiner, Isabelle

2014-06-01

238

Morphine-6-glucuronide: analgesic effects and receptor binding profile in rats  

SciTech Connect

The antinociceptive effects of morphine-6-glucuronide (M6G) were examined in two animal models of pain, the tail immersion test (reflex withdrawal to noxious heat) and the formalin test (behavioral response to minor tissue injury). In the tail immersion test, M6G produced and increase in withdrawal latency that rose rapidly between 0.01 and 0.025 ug ICV or 1 and 2 mg/kg SC. A further increase occurred at doses greater than 0.2 ug ICV or 4 mg/kg SC and was associated with marked catelepsy and cyanosis. Naloxone, 0.1 mg/kg SC, shifted the lower component of the dose-effect relation by a factor of 24. In the formalin test, 0.01 ug M6G ICV produced hyperalgesia, while between 0.05 and 0.2 ug ICV, antinociception increased rapidly without toxicity. The dose effect relations for hyperalgesia and antinociception were shifted to the right by factors of 20- and 3-fold, respectively. By comparison, ICV morphine was 60 (formalin test) to 145-200 (tail immersion test) times less potent than M6G. At sub-nanomolar concentrations, M6G enhanced the binding of (/sup 3/H)-etorphine, (/sup 3/H)-dihydromorphine and (/sup 3/H)-naloxone to rat brain membrane receptors by 20-40%. At higher concentrations, M6G displaced each ligand from binding sites, with K/sub i/ values of about 30 nM, as compared to morphine K/sub i/ values of about 3 nM.

Abbott, F.V.; Palmour, R.M.

1988-01-01

239

Rapid methods to enumerate Escherichia coli in foods using 4-methylumbelliferyl-beta-D-glucuronide.  

PubMed

Three methods to enumerate Escherichia coli in food were compared. They were based on AOAC methods using lauryl tryptose broth (LST) medium, LST-4-methylumbelliferyl-beta-D-glucuronide (MUG) medium, and a proposed method using regular LST in combination with E. coli (EC)-MUG medium. An efficacious and cost-effective method is needed that can detect E. coli and does not produce false presumptive positives. We tested 170 cheeses, 40 frozen processed seafood samples, 210 tree nuts, and 40 other samples. The method of choice for enumerating E. coli depends on the commodity itself. For a product, such as hard cheese or processed seafood, with a history of being negative for E. coli and other lactose-fermenting organisms, the proposed method using regular LST/EC-MUG is a good choice. These samples were seldom presumptive positive in the primary LST medium. If gas was produced, EC-MUG was an effective secondary medium. No false positives (fluorescence) or negatives were detected in EC-MUG medium. For a product with a history of being positive for E. coli and/or other lactose fermenting organisms, such as tree nutmeats or cheeses that are ripened by bacteria or mold, the method using LST-MUG is the method of choice. A presumptive positive in the LST-MUG medium was highly correlative with the biochemical tests that confirmed a sample contain E. coli. For samples spiked with E. coli, the results from each of these 3 methods were identical, and were consistent in enumerating E. coli. PMID:11324605

Ekholm, D F; Hirshfield, I N

2001-01-01

240

KEY COMPARISON: Final report on CCQM-K69 key comparison: Testosterone glucuronide in human urine  

NASA Astrophysics Data System (ADS)

The CCQM-K69 key comparison of testosterone glucuronide in human urine was organized under the auspices of the CCQM Organic Analysis Working Group (OAWG). The National Measurement Institute Australia (NMIA) acted as the coordinating laboratory for the comparison. The samples distributed for the key comparison were prepared at NMIA with funding from the World Anti-Doping Agency (WADA). WADA granted the approval for this material to be used for the intercomparison provided the distribution and handling of the material were strictly controlled. Three national metrology institutes (NMIs)/designated institutes (DIs) developed reference methods and submitted data for the key comparison along with two other laboratories who participated in the parallel pilot study. A good selection of analytical methods and sample workup procedures was displayed in the results submitted considering the complexities of the matrix involved. The comparability of measurement results was successfully demonstrated by the participating NMIs. Only the key comparison data were used to estimate the key comparison reference value (KCRV), using the arithmetic mean approach. The reported expanded uncertainties for results ranged from 3.7% to 6.7% at the 95% level of confidence and all results agreed within the expanded uncertainty of the KCRV. Main text. To reach the main text of this paper, click on Final Report. Note that this text is that which appears in Appendix B of the BIPM key comparison database kcdb.bipm.org/. The final report has been peer-reviewed and approved for publication by the CCQM, according to the provisions of the CIPM Mutual Recognition Arrangement (MRA).

Liu, Fong-Ha; Mackay, Lindsey; Murby, John

2010-01-01

241

FATAL MYOCARDITIS IN CHOLINE DEFICIENT RATS FED ETHYL LAURATE 1  

Microsoft Academic Search

In the course of a study of the relationship of chain length of dietary fatty acids to fatty liver (Stetten and Salcedo,'45), an unexpected mortality was encountered when rats on a choline-free diet were fed the ethyl ester of lauric acid. It was observed that of a total of sixteen rats on a synthetic diet containing 35% of ethyl laurate,

HOMER D. KE; JUAN SALCEDO; DEWITT STETTEN

242

IRIS TOXICOLOGICAL REVIEW OF METHYL ETHYL KETONE (2003 Final)  

EPA Science Inventory

EPA is announcing the release of the final report, "Toxicological Review of Methyl Ethyl Ketone: in support of the Integrated Risk Information System (IRIS)". The updated Summary for Methyl Ethyl Ketone and accompanying Quickview have also been added to the IRIS Database. ...

243

Metabolism of ethyl tiglate in apple fruits leads to the formation of small amounts of (R)-ethyl 2-methylbutanoate.  

PubMed

(S)-Ethyl 2-methylbutanoate is an important aroma compound in apples and serves as an indicator for genuineness of apple products due to its high optical purity of greater than 98% enantiomeric excess [T. Koenig and P. Schreier, Zeitsch. Lebensm.-Unters. Forsch. A, 1999, 208, 130-133; K. Schumacher et al., J. Agric. Food Chem., 1998, 46, 4496-4500]. The origin of minor amounts of (R)-ethyl 2-methylbutanoate is unknown as naturally occurring (+)-isoleucine, the proposed precursor of (S)-ethyl 2-methylbutanoate is enantiomerically pure. Since ethyl (E)-2-methyl-2-butenoate (ethyl tiglate) was recently discovered as a natural apple constituent and hydrogenation activity in apples was demonstrated we proposed ethyl tiglate as a precursor of (R)-ethyl 2-methylbutanoate. D4-3,4,4,4-ethyl tiglate was synthesized and was injected into ripe apple fruits (cv. Golden Delicious, Red Delicious and Granny Smith). After 3, 6, and 12 days apple volatiles were isolated by solid phase extraction on XAD-2 and the metabolites formed from D4-3,4,4,4-ethyl tiglate were analyzed by capillary gas chromatography-mass spectrometry (GC-MS). Ethyl 2-methylbutanoate, 2-methylbutyl acetate, 2-methylbutanol, and 2-methylbutanoic acid were identified as major transformation products. Chiral evaluation of the metabolites by multidimensional GC-MS revealed enantiomeric excesses ranging from 43% (S) to 30% (R) depending on the apple cultivar, sampling date and metabolite. The data show for the first time that the natural apple constituent ethyl tiglate can serve as a source for (R)-2-methylbutanol derivatives. PMID:11143814

Hauck, T; Weckerle, B; Schwab, W

2000-01-01

244

The gelation of oil using ethyl cellulose.  

PubMed

The characterization of the thermo-gelation mechanism and properties of ethyl cellulose/canola oil oleogels was performed using rheology and thermal analysis. Thermal analysis detected no evidence for thermal transitions contributed to secondary conformational changes, suggesting a gelation mechanism that does not involve secondary ordered structure formation. Rheological analysis demonstrated a relationship between the polymer molecular weight and the final gel strength, the cross-over behavior as well as the gel point temperature. Increasing polymer molecular weight led to an increase in final gel strength, the modulus at cross-over, and the gel point temperature. Cooling/heating rates affect gel modulus only for the low molecular weight samples. A decrease in gel strength with increasing cooling rate was detected. The cross-over temperature was not affected by the cooling/heating rates. Cooling rate also affected the gelation setting time where slow cooling rates produced a stable gel faster. PMID:25498711

Davidovich-Pinhas, M; Barbut, S; Marangoni, A G

2015-03-01

245

Effect of urinary pH on the pharmacokinetics of salicylic acid, with its glycine and glucuronide conjugates in human.  

PubMed

We studied the effects of urinary pH on the kinetics of salicylic acid (SA) with its metabolites and assessed the contribution of alkaline hydrolysis of salicylic acid acyl glucuronide to the renal clearance of salicylic acid. Hydrolysis of SAAG in alkaline urine contributes marginally to the high renal clearance and excretion of salicylic acid, validating alkalinization of a patient with SA overdose. Under acidic urine conditions, salicylic acid (SA) had a terminal plasma t1/2 value of 3.29 +/- 0.52 hours while under alkaline urine conditions this t1/2 was significantly reduced to 2.50 +/- 0.41 hours (p = 0.0156). The total oral body clearance of salicylic acid under acidic conditions (1.38 +/- 0.43 l/h) is significantly lower than under alkaline urine conditions (2.27 +/- 0.83 l/h; p = 0.0410). The Km and Vmax values of SA, and its conjugates salicylic acid phenolic glucuronide (SAPG), salicyluric acid (SU) and salicyluric acid phenolic glucuronide (SUPG) did not differ statistically under acidic and alkaline urine conditions. The protein binding of SA was 93.8 +/- 1.0% and that of SU was 89.7 +/- 2.2% in vivo and in vitro. SUPG had a protein binding of 84.8 +/- 1.8%, while SAPG showed no protein binding at all. The renal excretion of salicylic acid depends strongly on the urinary pH. The percentage of the dose excreted unchanged increased from 2.3 +/- 1.5% under acidic conditions to 30.5 +/- 9.1% under alkaline conditions (p = 0.0006). Alkaline urine lowered by 50% the percentage of the dose excreted as SU (p = 0.0028), SAAG (p = 0.0013), and SUPG (p = 0.0296), while SAPG is only marginally lowered (p = 0.0589).(ABSTRACT TRUNCATED AT 250 WORDS) PMID:7834163

Vree, T B; Van Ewijk-Beneken Kolmer, E W; Verwey-Van Wissen, C P; Hekster, Y A

1994-10-01

246

19 CFR 10.99 - Importation of ethyl alcohol for nonbeverage purposes.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 false Importation of ethyl alcohol for nonbeverage purposes. 10.99 Section...REDUCED RATE, ETC. General Provisions Ethyl Alcohol § 10.99 Importation of ethyl alcohol for nonbeverage purposes. (a)...

2011-04-01

247

19 CFR 10.99 - Importation of ethyl alcohol for nonbeverage purposes.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 false Importation of ethyl alcohol for nonbeverage purposes. 10.99 Section...REDUCED RATE, ETC. General Provisions Ethyl Alcohol § 10.99 Importation of ethyl alcohol for nonbeverage purposes. (a)...

2013-04-01

248

19 CFR 10.99 - Importation of ethyl alcohol for nonbeverage purposes.  

Code of Federal Regulations, 2010 CFR

...2010-04-01 false Importation of ethyl alcohol for nonbeverage purposes. 10.99 Section...REDUCED RATE, ETC. General Provisions Ethyl Alcohol § 10.99 Importation of ethyl alcohol for nonbeverage purposes. (a)...

2010-04-01

249

19 CFR 10.99 - Importation of ethyl alcohol for nonbeverage purposes.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 false Importation of ethyl alcohol for nonbeverage purposes. 10.99 Section...REDUCED RATE, ETC. General Provisions Ethyl Alcohol § 10.99 Importation of ethyl alcohol for nonbeverage purposes. (a)...

2012-04-01

250

40 CFR 180.430 - Fenoxaprop-ethyl; tolerances for residues.  

Code of Federal Regulations, 2014 CFR

...Tolerances are established for residues of the herbicide fenoxaprop-ethyl, including...tolerances are established for residues of the herbicide fenoxaprop-ethyl...are established for residues of the herbicide fenoxaprop-ethyl,...

2014-07-01

251

40 CFR 721.7290 - Propanoic acid, 2-(trimethoxysilyl)-, ethyl ester.  

Code of Federal Regulations, 2010 CFR

...acid, 2-(trimethoxysilyl)-, ethyl ester. 721.7290 Section 721.7290 ...acid, 2-(trimethoxysilyl)-, ethyl ester. (a) Chemical substance and significant...acid, 2-(trimethoxysilyl)-, ethyl ester (PMN P-01-22; CAS No....

2010-07-01

252

Parameters Affecting Ethyl Ester Production by Saccharomyces cerevisiae during Fermentation?  

PubMed Central

Volatile esters are responsible for the fruity character of fermented beverages and thus constitute a vital group of aromatic compounds in beer and wine. Many fermentation parameters are known to affect volatile ester production. In order to obtain insight into the production of ethyl esters during fermentation, we investigated the influence of several fermentation variables. A higher level of unsaturated fatty acids in the fermentation medium resulted in a general decrease in ethyl ester production. On the other hand, a higher fermentation temperature resulted in greater ethyl octanoate and decanoate production, while a higher carbon or nitrogen content of the fermentation medium resulted in only moderate changes in ethyl ester production. Analysis of the expression of the ethyl ester biosynthesis genes EEB1 and EHT1 after addition of medium-chain fatty acid precursors suggested that the expression level is not the limiting factor for ethyl ester production, as opposed to acetate ester production. Together with the previous demonstration that provision of medium-chain fatty acids, which are the substrates for ethyl ester formation, to the fermentation medium causes a strong increase in the formation of the corresponding ethyl esters, this result further supports the hypothesis that precursor availability has an important role in ethyl ester production. We concluded that, at least in our fermentation conditions and with our yeast strain, the fatty acid precursor level rather than the activity of the biosynthetic enzymes is the major limiting factor for ethyl ester production. The expression level and activity of the fatty acid biosynthetic enzymes therefore appear to be prime targets for flavor modification by alteration of process parameters or through strain selection. PMID:17993562

Saerens, S. M. G.; Delvaux, F.; Verstrepen, K. J.; Van Dijck, P.; Thevelein, J. M.; Delvaux, F. R.

2008-01-01

253

Mechanistic insight into alkylation of the ethyl acetoacetate anion with different ethyl halides  

NASA Astrophysics Data System (ADS)

The alkylation reactions of the ambident ethyl acetoacetate anion with C2H5X (X = F, Cl, Br, and I) in the O2, C3, and O4 positions of the anion were investigated at the B3LYP/6-311+G( d,p) level of theory. It was found that the ethylation reaction does not occur in the position O4, as well as with ethyl fluoride in any position of the anion, due to very high activation energies and thermodynamic instability of the hypothetic products. The activation energies for the reactions in the position O2 are lower in comparison to the position C3, but the products of the reactions in the C3 position are more stable than those in the position O4, implying that the C/O products ratio is controlled by both thermodynamic and kinetic factors, leading to the O2-product with the chloride, and C3-product with the iodide as leaving group.

Markovi?, S.; ?ur?evi?, J.; Vukosavljevi?, M.; Petrovi?, Z.

2013-12-01

254

Simultaneous quantification of atomoxetine as well as its primary oxidative and O-glucuronide metabolites in human plasma and urine using liquid chromatography tandem mass spectrometry (LC/MS/MS).  

PubMed

A sensitive and selective liquid chromatography tandem mass spectrometry (LC/MS/MS) method for the determination of atomoxetine and its metabolites (4-hydroxyatomoxetine, N-des-methylatomoxetine, and 4-hydroxyatomoxetine-O-glucuronide) has been developed for human plasma and urine. Using stable-labeled internal standards, the method proved to be accurate and precise for the analytes in all species, resulting in inter-batch accuracy (percent relative error, %RE) within 100+/-13% and inter-batch precision (relative standard deviation, %RSD) within 11%. Stability was demonstrated for the analytes in neat solutions and the reconstitution solvent, as well as plasma and urine (with or without the deconjugation reagent). The method was simple, robust (utilized for the analysis of several hundred clinical study samples), and amenable to high sample throughput. PMID:15967301

Mullen, John H; Shugert, Richard L; Ponsler, George D; Li, Qimin; Sundaram, Bhaskar; Coales, Heather L; Yakupkovic, Joseph E; Lelacheur, Richard M; Wheeler, William J; Belas, Frank J; Sauer, John-Michael

2005-07-15

255

Retention of ethyl butyrate by gellan gels in the presence of potassium ions  

Microsoft Academic Search

The air\\/biopolymer partition coefficient (K) and percentage of retention (R%) of ethyl butyrate (400ppm) added to gellan gels were determined, using static headspace gas chromatography. Potassium chloride (40–120mM) was used to induce gellan gelation. When 5g of sample were left to equilibrate at 37°C for 2 and 24h, the coefficient values initially decreased with salt concentration to a certain value

Vasiliki Evageliou; Panagiota Galanaki; Chryssavgi Gardeli; Michael Komaitis

2011-01-01

256

Microwave Spectrum, Structural Parameters and Quadrupole Coupling for Azaborine and 1-ETHYL-AZABORINE  

Microsoft Academic Search

The first microwave spectra for the unusual and elusive aromatic molecules, 1,2-dihydro-1,2-azaborine (azaborine) and 1-ethyl-azaborine have been measured, in the 7-18 GHz range, providing accurate rotational constants, nitrogen and boron quadrupole coupling strengths, important bond lengths and other structural parameters. Azaborine (BNC_4H_6)is an aromatic, B-N substituted analog of benzene, the quintessential aromatic molecule. The experimental bond lengths determined for azaborine

Adam Daly; Stephen G. Kukolich; Chakree Tanjaroon; Adam J. V. Marwitz; Shih-Yuan Liu

2010-01-01

257

Effect of ethyl esterification of phenolic acids on low-density lipoprotein oxidation  

Microsoft Academic Search

Inhibition of copper-induced low-density lipoprotein (LDL) oxidation by phenolic acids and their ethyl esters was investigated. LDL oxidation was evaluated by the hydroperoxide concentration and the chromatographic pattern of apoprotein fractions after fast protein liquid chromatography (FPLC). Antiradical properties against 1,1-diphenyl-2-picryl hydrazyl (DPPH) radical and 2,2’-azobis(2-amidinopropane)dihydrochloride (AAPH) were also investigated, and lipophilicity determined by thin-layer chromatography.Caffeic acid at 5 ?M and

J. Chalas; C. Claise; M. Edeas; C. Messaoudi; L. Vergnes; A. Abella; A. Lindenbaum

2001-01-01

258

Sequence analysis of N-ethyl-N-nitrosourea-induced vermilion mutations in Drosophila melanogaster  

Microsoft Academic Search

The mutational specificity of N-ethyl-N-nitrosourea (ENU) was determined in Drosophila melanogaster using the vermilion locus as a target gene. 25 mutants (16 F⁠and 9 Fâ mutants) were cloned and sequenced. Only base-pair changes were observed; three of the mutants represented double base substitutions. Transition mutations were the most prominent sequence change: 61% were GC â AT and 18% AT

Albert Pastink; Cees Vreeken; Madeleine J. M. Nivard; E. W. Vogel; L. L. Searles

1989-01-01

259

Start of oral morphine to cancer patients: effective serum morphine concentrations and contribution from morphine-6-glucuronide to the analgesia produced by morphine  

Microsoft Academic Search

Objective: To investigate the serum concentrations of morphine, morphine-3-glucuronide (M3G) and morphine-6-glucuronide (M6G) and the\\u000a relationships between serum concentrations and clinical effects associated with start of morphine treatment in cancer patients.\\u000a \\u000a \\u000a \\u000a Methods: Forty patients with malignant disease and intolerable pain on weak opioids (codeine\\/dextropropoxyphen) were included. After\\u000a a wash-out period, titration with immediate-release (IR) morphine was started. When a stable

P. Klepstad; S. Kaasa; P. C. Borchgrevink

2000-01-01

260

Protective Effect of Ethyl Acetate Fraction of Stereospermum Suaveolens Against Hepatic Oxidative Stress in STZ Diabetic Rats  

PubMed Central

Stereospermum suaveolens is a folk remedy for the treatment of diabetes and liver disorders in southern parts of India. In the present study, the protective effect of the ethyl acetate fraction of ethanol extract from S. suaveolens against hepatic oxidative stress was evaluated in streptozotocin (STZ)-induced diabetic rats for 14 days. The ethyl acetate fraction was administered orally to the STZ diabetic rats at the doses of 200 and 400 mg/kg. Blood glucose level was measured according to glucose oxidase method. In order to determine hepatoprotective activity, changes in the levels of serum biomarker enzymes such as aspartate transaminase (AST), alanine transaminase (ALT), and serum alkaline phosphatase (SALP) were assessed in the ethyl acetate fraction treated diabetic rats and were compared with the levels in diabetic control rats. In addition, the antioxidant activity of ethyl acetate fraction was evaluated using various hepatic parameters such as thiobarbituric acid reactive substances (TBARS), reduced glutathione (GSH), superoxide dismutase (SOD), and catalase (CAT). It was found that administration of ethyl acetate fraction (200 and 400 mg/kg) produced a significant (P < 0.001) fall in fasting blood glucose level, TBARS, bilirubin, AST, ALT, and SALP, while elevating the GSH levels, and SOD and CAT activities in diabetic rats. Histopathologic studies also revealed the protective effect of ethyl acetate fraction on the liver tissues of diabetic rats. It was concluded from this study that the ethyl acetate fraction from ethanol extract of S. suaveolens modulates the activity of enzymatic and nonenzymatic antioxidants and enhances the defense against hepatic oxidative stress in STZ-induced diabetic rats. PMID:24716175

Balasubramanian, Thirumalaiswamy; Senthilkumar, G. P; Karthikeyan, M.; Chatterjee, Tapan Kumar

2013-01-01

261

Excess molar enthalpies of eight binary mixtures containing 1,2-epoxybutane + ethyl alkanoates at 298.15 K  

Microsoft Academic Search

Excess molar enthalpies, HEm, have been measured using a flow microcalorimeter at 298.15K and at atmospheric pressure for the eight mixtures containing 1,2-epoxybutane with ethyl acetate, ethyl propanoate, ethyl butyrate, ethyl pentanoate, ethyl hexanoate, ethyl heptanoate, ethyl octanoate and ethyl decanoate. Excess heats of mixing, HEm, are positive for all the mixtures and increase with the chain length of the

Fabio Comelli; Romolo Francesconi

1998-01-01

262

Metabolic engineering of Escherichia coli for the biosynthesis of flavonoid-O-glucuronides and flavonoid-O-galactoside.  

PubMed

Most flavonoids are glycosylated and the nature of the attached sugar can strongly affect their physiological properties. Although many flavonoid glycosides have been synthesized in Escherichia coli, most of them are glucosylated. In order to synthesize flavonoids attached to alternate sugars such as glucuronic acid and galactoside, E. coli was genetically modified to express a uridine diphosphate (UDP)-dependent glycosyltransferase (UGT) specific for UDP-glucuronic acid (AmUGT10 from Antirrhinum majus or VvUGT from Vitis vinifera) and UDP-galactoside (PhUGT from Petunia hybrid) along with the appropriate nucleotide biosynthetic genes to enable simultaneous production of their substrates, UDP-glucuronic acid and UDP-galactose. To engineer UDP-glucuronic acid biosynthesis, the araA gene encoding UDP-4-deoxy-4-formamido-L-arabinose formyltransferase/UDP-glucuronic acid C-4? decarboxylase, which also used UDP-glucuronic acid as a substrate, was deleted in E. coli, and UDP-glucose dehydrogenase (ugd) gene was overexpressed to increase biosynthesis of UDP-glucuronic acid. Using these strategies, luteolin-7-O-glucuronide and quercetin-3-O-glucuronide were biosynthesized to levels of 300 and 687 mg/L, respectively. For the synthesis of quercetin 3-O-galactoside, UGE (encoding UDP-glucose epimerase from Oryza sativa) was overexpressed along with a glycosyltransferase specific for quercetin and UDP-galactose. Using this approach, quercetin 3-O-galactoside was successfully synthesized to a level of 280 mg/L. PMID:25515812

Kim, So Yeon; Lee, Hye Rin; Park, Kwang-Su; Kim, Bong-Gyu; Ahn, Joong-Hoon

2015-03-01

263

Methods for determination of conjugated bilirubin in rat faeces.  

PubMed

Conjugated bilirubin was prepared from the faeces of germ-free (GF) rats by three different preparative methods. The bilirubin conjugate preparations were coupled with diazotized ethyl anthranilate and the formed ethyl anthranilate azopigments were quantified spectrophotometrically and separated by thin-layer chromatography (tlc). The most polar azopigment was purified by tlc and subjected to ammonolysis followed by tlc of the released saccaride. As a result of this procedure, only glucuronic acid was detected as the conjugating saccaride thus indicating that the most polar azopigment prepared from GF rat faeces was the delta ethyl anthranilate azopigment. Reference azopigments were prepared from GF rat small intestinal contents and subjected to separation by tlc. The azopigment pattern was very similar to the pattern obtained with the faecal azopigment preparations and a maximum of ten separated azopigment spots were detected. The findings indicated that, in addition to bilirubin glucuronides, other bilirubin conjugates with unknown structure are excreted with the faeces of GF rats. One of the preparative methods used for the preparation of conjugated bilirubin from GF rat faeces was tested on faeces from conventional (CONV) rats. From these preparations, no ethyl anthranilate azopigments were formed, thus indicating that faeces from CONV rats is devoid of conjugated bilirubin. PMID:6484491

Saxerholt, H; Midtvedt, T; Gustafsson, B E

1984-10-01

264

Identification and determination of carboxylic acids in food samples using 2-(2-(anthracen-10-yl)-1 H-phenanthro[9,10- d]imidazol-1-yl)ethyl 4-methylbenzenesulfonate (APIETS) as labeling reagent by HPLC with FLD and APCI\\/MS  

Microsoft Academic Search

A new labeling reagent for carboxylic acids, 2-(2-(anthracen-10-yl)-1H-phenanthro[9,10-d]imidazol-1-yl)ethyl 4-methylbenzenesulfonate (APIETS) has been designed and synthesized. It was used to label eight fatty acids (lauric acid, myristic acid, palmitic acid, stearic acid, arachidic acid, oleic acid, linoleic acid and linolenic acid) and four hydroxy pentacyclic triterpene acids (oleanolic acid, ursolic acid, betulinic acid and maslinic acid), successfully. APIETS could easily and

Zhiwei Sun; Jinmao You; Cuihua Song; Lian Xia

2011-01-01

265

Studies on molecular interactions and fluid structure of anisole with 2-ethyl-1-hexanol and decyl alcohol  

Microsoft Academic Search

The dielectric studies of a liquid can give information on its structure and interaction. Dielectric study of anisole has been carried out by mixing it with alcohols namely 1) 2-ethyl-l-hexanol and 2) decyl alcohol at different temperatures. The Kirkwood correlation factor, the excess dielectric permittivity, Bruggeman parameter and the thermodynamic properties of the mixtures have been determined and the results

G. Parthipan; T. Thenappan

2007-01-01

266

In Vitro Germination and Dormancy Responses of Hydrangea macrophylla and Hydrangea paniculata Seeds to Ethyl Methane Sulfonate and Cold Treatment  

Technology Transfer Automated Retrieval System (TEKTRAN)

In order to determine the optimal conditions for mutagenesis of Hydrangea macrophylla and Hydrangea paniculata, stratified and non-stratified seeds from representative cultivars were treated with 0.5%, 2.5%, and 5% ethyl methanesulfonate (EMS). In the M1 generation, most non-stratified H macrophylla...

267

46 CFR 151.50-42 - Ethyl ether.  

Code of Federal Regulations, 2011 CFR

...subpart 111.105 of this chapter. (f) Copper, silver, mercury and magnesium or other acetylide forming metals and their...liquid. (g) Precautions shall be taken to prevent the contamination of ethyl ether by strong oxidizing agents. (h) The...

2011-10-01

268

46 CFR 151.50-42 - Ethyl ether.  

Code of Federal Regulations, 2013 CFR

...subpart 111.105 of this chapter. (f) Copper, silver, mercury and magnesium or other acetylide forming metals and their...liquid. (g) Precautions shall be taken to prevent the contamination of ethyl ether by strong oxidizing agents. (h) The...

2013-10-01

269

46 CFR 151.50-42 - Ethyl ether.  

Code of Federal Regulations, 2012 CFR

...subpart 111.105 of this chapter. (f) Copper, silver, mercury and magnesium or other acetylide forming metals and their...liquid. (g) Precautions shall be taken to prevent the contamination of ethyl ether by strong oxidizing agents. (h) The...

2012-10-01

270

46 CFR 151.50-42 - Ethyl ether.  

Code of Federal Regulations, 2014 CFR

...subpart 111.105 of this chapter. (f) Copper, silver, mercury and magnesium or other acetylide forming metals and their...liquid. (g) Precautions shall be taken to prevent the contamination of ethyl ether by strong oxidizing agents. (h) The...

2014-10-01

271

Extending the detection window of diazepam by directly analyzing its glucuronide metabolites in human urine using liquid chromatography-tandem mass spectrometry.  

PubMed

A method for the simultaneous direct analysis of diazepam oxazepam glucuronide, temazepam glucuronide, oxazepam, nordiazepam, and temazepam in human urine was developed and validated. Urine sample was purified by solid phase extraction (SPE), and the analysis was achieved using a liquid chromatography-tandem mass spectrometry (LC-MS/MS) system equipped with an electrospray ionization source (ESI). Multiple reaction monitoring (MRM) mode was used to analyze the target compounds. Extraction recoveries were 65-122% for all the analytes. The method showed acceptable intra-assay and inter-assay precision (both relative standard deviation (RSD)?11.2%) for quality control (QC) samples. The limits of detections (LODs) were in the range of 0.1-2 ng/mL. The present assay was applied to analyze the urine obtained from three volunteers after oral administration of a single dose 5mg of diazepam. The results showed that, the detection periods of oxazepam glucuronide and temazepam glucuronide were much longer than diazepam and other metabolites. PMID:23122274

Wang, Xin; Wang, Rong; Zhang, Yurong; Liang, Chen; Ye, Haiying; Cao, Fangqi; Rao, Yulan

2012-12-14

272

Ethyl Carbamate in Foods and Beverages – A Review  

Microsoft Academic Search

\\u000a Foods and beverages contain many toxic chemicals that raise health concerns. Ethyl carbamate (EC) or urethane is the ethyl\\u000a ester of carbamic acid. It occurs at low levels, from ng\\/L to mg\\/L, in many fermented foods and beverages. EC is genotoxic\\u000a and carcinogenic for a number of species such as mice, rats, hamsters and monkeys. It has been classified as

J. V. Weber; V. I. Sharypov

273

Molecular interactions in alcohol–ethyl methacrylate mixtures  

Microsoft Academic Search

Molecular interaction between alcohols (1-propanol, 1-butanol, s-butanol, t-butanol, 1-pentanol, 1-heptanol, 1-octanol and 1-decanol) with ethyl methacrylate has been studied in n-heptane, CCl4 and benzene at 298K using FTIR spectroscopic and dielectric methods. The result obtained from both the methods indicates only the existence of most likely 1:1 complex formation between the alcohol and ethyl methacrylate in these systems. The alkyl

K. Dharmalingam; K. Ramachandran; P. Sivagurunathan; G. M. Kalamse

2008-01-01

274

Gauche Ethyl Alcohol: Laboratory Assignments and Interstellar Identification  

NASA Technical Reports Server (NTRS)

Ethyl alcohol (ethanol) is known to possess a pair of closely spaced excited torsional substates (gauche+, gauche-) at an energy of approximately 57 K above the ground (trans) torsional substate. We report an extended analysis of some gauche - gauche+ Q-branch ((Delta)J = 0) transitions with a three-substate fixed frame axis method (FFAM) Hamiltonian. Our approach accounts for complex trans-gauche interactions for the first time. In addition, we are able to obtain intensities for perturbed rotational transitions, and to determine the trans to gauche+ separation to be 1185399.1 MHz. A complete ground state rotational-torsional partition function accounting for the previously neglected gauche substates is presented. Based on our analysis, a total of 14 U lines obtained towards Orion KL can now be assigned to gauche substates of ethanol. Analysis of these lines yields a rotational temperature of 223 K and a total (trans + gauche) column density of 7.0 x 10(exp 15)/sq cm. The column density is in reasonable agreement with the recent value of 2-3 x 10(exp 15)/sq cm based on observations of trans-ethanol by Ohishi et al., although there is some disparity in the rotational temperatures. Eight additional U lines in the literature are assigned to transitions of gauche ethanol.

Pearson, J. C.; Sastry, K. V. L. N.; Herbst, Eric; DeLucia, Frank C.

1997-01-01

275

Quantification of free mycophenolic acid and its glucuronide metabolite in human plasma by liquid-chromatography using mass spectrometric and ultraviolet absorbance detection.  

PubMed

The immunosuppressant drug mycophenolic acid (MPA) and its major metabolite, mycophenolic acid glucuronide (MPAG), are highly bound to albumin. An HPLC-tandem-MS (HPLC/MS/MS) and an HPLC-UV assay were developed to measure free (unbound) concentrations of MPA and MPAG, respectively. Ultrafiltrate was prepared from plasma (500 microl) by ultrafiltration at 3000 x g for 20 min (20 degrees C). Both MPA and MPAG were isolated from ultrafiltrate (100 microl) by acidification and C18 solid-phase extraction. Free MPA was measured by electrospray tandem mass spectrometry using selected reactant monitoring (MPA: m/z 338.2--> 206.9) in positive ionisation mode. Chromatography was performed on a PFPP column (50 mm x 2 mm, 5 microm). Total analysis time was 7 min. The assay was linear over the range 1-200 microg/l with a limit of quantification of 1 microg/l. The inter-day accuracy and imprecision of quality controls (7.5, 40, 150 microg/l) were 94-99% and < 7%, respectively. Free MPAG was chromatographed on a C18 Nova-Pak column (150 mm x 3.9 mm, 5 microm) using a binary gradient over 20 min. The eluent was monitored at 254 nm. The assay was linear over the range 1-50 mg/l with the limit of quantification at 2.5 mg/l. The inter-day accuracy and imprecision of quality controls (5, 20, 45 mg/l) was 101-107% and < 8% (n = 4), respectively. For both methods no interfering substances were found in ultrafiltrate from patients not receiving MPA. The methods described have a suitable dynamic linear range to facilitate the investigation of free MPA and MPAG pharmacokinetics in transplant patients. Further, this is the first reported HPLC-UV method to determine free MPAG concentrations. PMID:14659448

Atcheson, Bronwyn; Taylor, Paul J; Mudge, David W; Johnson, David W; Pillans, Peter I; Tett, Susan E

2004-01-01

276

In vitro protection of biological macromolecules against oxidative stress and in vivo toxicity evaluation of Acacia nilotica (L.) and ethyl gallate in rats  

PubMed Central

Background Recently, enormous research has been focused on natural bioactive compounds possessing potential antioxidant and anticancer properties using cell lines and animal models. Acacia nilotica (L.) is widely distributed in Asia, Africa, Australia and Kenya. The plant is traditionally used to treat mouth, ear and bone cancer. However, reports on Acacia nilotica (L.) Wild. Ex. Delile subsp. indica (Benth.) Brenan regarding its toxicity profile is limited. Hence in this study, we investigated the antioxidant capacity and acute toxicity of ethyl gallate, a phenolic antioxidant present in the A. nilotica (L.) leaf extract. Methods The antioxidant activity of ethyl gallate against Fenton’s system (Fe3+/H2O2/ascorbic acid) generated oxidative damage to pBR322 DNA and BSA was investigated. We also studied the interaction of ethyl gallate to CT-DNA by wave scan and FTIR analysis. The amount of ethyl gallate present in the A. nilotica (L.) leaf extract was calculated using HPLC and represented in gram equivalence of ethyl gallate. The acute toxicity profile of ethyl gallate in the A. nilotica (L.) leaf extract was analyzed in albino Wistar rats. Measurement of liver and kidney function markers, total proteins and glucose were determined in the serum. Statistical analysis was done using statistical package for social sciences (SPSS) tool version 16.0. Results Ethyl gallate was found to be effective at 100 ?g/mL concentration by inhibiting the free radical mediated damage to BSA and pBR322 DNA. We also found that the interaction of ethyl gallate and A. nilotica (L.) leaf extract to CT-DNA occurs through intercalation. One gram of A. nilotica (L.) leaf extract was found to be equivalent to 20 mg of ethyl gallate through HPLC analysis. Based on the acute toxicity results, A. nilotica (L.) leaf extract and ethyl gallate as well was found to be non-toxic and safe. Conclusions Results revealed no mortality or abnormal biochemical changes in vivo and the protective effect of A. nilotica (L.) leaf extract and ethyl gallate on DNA and protein against oxidative stress in vitro. Hence, A. nilotica (L.) leaf extract or ethyl gallate could be used as potential antioxidants with safe therapeutic application in cancer chemotherapy. PMID:25043389

2014-01-01

277

Pharmacokinetic role of protein binding of mycophenolic acid and its glucuronide metabolite in renal transplant recipients.  

PubMed

Mycophenolic acid (MPA), the active compound of mycophenolate mofetil (MMF), is used to prevent graft rejection in renal transplant recipients. MPA is glucuronidated to the metabolite MPAG, which exhibits enterohepatic recirculation (EHC). MPA binds for 97% and MPAG binds for 82% to plasma proteins. Low plasma albumin concentrations, impaired renal function and coadministration of cyclosporine have been reported to be associated with increased clearance of MPA. The aim of the study was to develop a population pharmacokinetic model describing the relationship between MMF dose and total MPA (tMPA), unbound MPA (fMPA), total MPAG (tMPAG) and unbound MPAG (fMPAG). In this model the correlation between pharmacokinetic parameters and renal function, plasma albumin concentrations and cotreatment with cyclosporine was quantified. tMPA, fMPA, tMPAG and fMPAG concentration-time profiles of renal transplant recipients cotreated with cyclosporine (n = 48) and tacrolimus (n = 45) were analyzed using NONMEM. A 2- and 1-compartment model were used to describe the pharmacokinetics of fMPA and fMPAG. The central compartments of fMPA and fMPAG were connected with an albumin compartment allowing competitive binding (bMPA and bMPAG). tMPA and tMPAG were modeled as the sum of the bound and unbound concentrations. EHC was modeled by transport of fMPAG to a separate gallbladder compartment. This transport was decreased in case of cyclosporine cotreatment (P < 0.001). In the model, clearance of fMPAG decreased when creatinine clearance (CrCL) was reduced (P < 0.001), and albumin concentration was correlated with the maximum number of binding sites available for MPA and MPAG (P < 0.001). In patients with impaired renal function cotreated with cyclosporine the model adequately described that increasing fMPAG concentrations decreased tMPA AUC due to displacement of MPA from its binding sites. The accumulated MPAG could also be reconverted to MPA by the EHC, which caused increased tMPA AUC in patients cotreated with tacrolimus. Changes in CrCL had hardly any effect on fMPA exposure. A decrease in plasma albumin concentration from 0.6 to 0.4 mmol/l resulted in ca. 38% reduction of tMPA AUC, whereas no reduction in fMPA AUC was seen. In conclusion, a pharmacokinetic model has been developed which describes the relationship between dose and both total and free MPA exposure. The model adequately describes the influence of renal function, plasma albumin and cyclosporine co-medication on MPA exposure. Changes in protein binding due to altered renal function or plasma albumin concentrations influence tMPA exposure, whereas fMPA exposure is hardly affected. PMID:19904584

de Winter, Brenda C M; van Gelder, Teun; Sombogaard, Ferdi; Shaw, Leslie M; van Hest, Reinier M; Mathot, Ron A A

2009-12-01

278

Urinary levels of the tobacco-specific carcinogen N?-nitrosonornicotine and its glucuronide are strongly associated with esophageal cancer risk in smokers  

PubMed Central

N?-Nitrosonornicotine (NNN) and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK) are tobacco-specific nitrosamines. NNN and NNK can induce cancers of the esophagus and lung, respectively, in laboratory animals, but data on human esophageal cancer are lacking. The association between levels of NNN and 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNAL), an NNK metabolite, in urine samples collected before diagnosis and risk of esophageal cancer was examined in 77 patients with esophageal cancer and 223 individually matched controls, all current smokers, from a cohort of 18244 Chinese men in Shanghai, China, followed from 1986 to 2008. Urinary total NNN (free NNN plus NNN-N-glucuronide) was significantly higher, whereas the percentage of its detoxification product NNN-N-glucuronide was significantly lower in cases than controls. Odds ratios (95% confidence intervals) of esophageal cancer for the second and third tertiles of total NNN were 3.99 (1.25–12.7) and 17.0 (3.99–72.8), respectively, compared with the first tertile after adjustment for urinary total NNAL and total cotinine and smoking intensity and duration (Ptrend < 0.001). The corresponding figures for the percentage of NNN-N-glucuronides were 0.37 (0.17–0.80) and 0.27 (0.11–0.62) (Ptrend = 0.001). Urinary total NNN and the percentage of NNN-N-glucuronides almost completely accounted for the observed association for urinary total NNAL (free NNAL plus its glucuronides), urinary total cotinine and smoking intensity with esophageal cancer risk. These findings along with results of previous studies in laboratory animals support a significant and unique role of NNN in esophageal carcinogenesis in humans. PMID:21734256

Yuan, Jian-Min; Knezevich, Aleksandar D.; Wang, Renwei; Gao, Yu-Tang; Hecht, Stephen S.; Stepanov, Irina

2011-01-01

279

Subchronic Toxicity Study in Rats of Two New Ethyl-Carbamates with Ixodicidal Activity  

PubMed Central

Female and male Wistar rats were used to determine the subchronic oral toxicities of two new ethyl-carbamates with ixodicidal activities (ethyl-4-bromphenyl-carbamate and ethyl-4-chlorphenyl-carbamate). The evaluated carbamates were administered in the drinking water (12.5, 25 and 50?mg/kg/day) for 90 days. Exposure to the evaluated carbamates did not cause mortality or clinical signs and did not affect food consumption or weight gain. However, exposure to these carbamates produced alterations in water consumption, hematocrit, percentages of reticulocytes, plasma proteins, some biochemical parameters (aspartate aminotransferase, gamma-glutamyl transpeptidase, cholinesterase, and creatinine activities), thiobarbituric acid reactive substances, and the relative weight of the spleen. Histologically, slight pathological alterations were found in the liver that were consistent with the observed biochemical alterations. The nonobserved adverse effect levels (NOAELs) of the evaluated carbamates were 12.5?mg/kg/day for both the female and male rats. The low severity and reversibility of the majority of the observed alterations suggest that the evaluated carbamates have low subchronic toxicity. PMID:24818142

Prado-Ochoa, María Guadalupe; Abrego-Reyes, Víctor Hugo; Velázquez-Sánchez, Ana María; Muñoz-Guzmán, Marco Antonio; Ramírez-Noguera, Patricia; Angeles, Enrique; Alba-Hurtado, Fernando

2014-01-01

280

Chemodynamics of methyl parathion and ethyl parathion: adsorption models for sustainable agriculture.  

PubMed

The toxicity of organophosphate insecticides for nontarget organism has been the subject of extensive research for sustainable agriculture. Pakistan has banned the use of methyl/ethyl parathions, but they are still illegally used. The present study is an attempt to estimate the residual concentration and to suggest remedial solution of adsorption by different types of soils collected and characterized for physicochemical parameters. Sorption of pesticides in soil or other porous media is an important process regulating pesticide transport and degradation. The percentage removal of methyl parathion and ethyl parathion was determined through UV-Visible spectrophotometer at 276 nm and 277 nm, respectively. The results indicate that agricultural soil as compared to barren soil is more efficient adsorbent for both insecticides, at optimum batch condition of pH 7. The equilibrium between adsorbate and adsorbent was attained in 12 hours. Methyl parathion is removed more efficiently (by seven orders of magnitude) than ethyl parathion. It may be attributed to more available binding sites and less steric hindrance of methyl parathion. Adsorption kinetics indicates that a good correlation exists between distribution coefficient (Kd) and soil organic carbon. A general increase in Kd is noted with increase in induced concentration due to the formation of bound or aged residue. PMID:24689059

Tabassum, Noshabah; Rafique, Uzaira; Balkhair, Khaled S; Ashraf, Muhammad Aqeel

2014-01-01

281

Chemodynamics of Methyl Parathion and Ethyl Parathion: Adsorption Models for Sustainable Agriculture  

PubMed Central

The toxicity of organophosphate insecticides for nontarget organism has been the subject of extensive research for sustainable agriculture. Pakistan has banned the use of methyl/ethyl parathions, but they are still illegally used. The present study is an attempt to estimate the residual concentration and to suggest remedial solution of adsorption by different types of soils collected and characterized for physicochemical parameters. Sorption of pesticides in soil or other porous media is an important process regulating pesticide transport and degradation. The percentage removal of methyl parathion and ethyl parathion was determined through UV-Visible spectrophotometer at 276?nm and 277?nm, respectively. The results indicate that agricultural soil as compared to barren soil is more efficient adsorbent for both insecticides, at optimum batch condition of pH 7. The equilibrium between adsorbate and adsorbent was attained in 12 hours. Methyl parathion is removed more efficiently (by seven orders of magnitude) than ethyl parathion. It may be attributed to more available binding sites and less steric hindrance of methyl parathion. Adsorption kinetics indicates that a good correlation exists between distribution coefficient (Kd) and soil organic carbon. A general increase in Kd is noted with increase in induced concentration due to the formation of bound or aged residue. PMID:24689059

Rafique, Uzaira; Balkhair, Khaled S.; Ashraf, Muhammad Aqeel

2014-01-01

282

In vitro evaluation of transdermal patches of flurbiprofen with ethyl cellulose.  

PubMed

This study was aimed to determine effects of penetration enhancers and plasticizers on drug release from rationally designed formulations of flurbiprofen based transdermal drug delivery system. Matrix type transdermal patches were formulated with ethyl cellulose (EC) as a polymer by using plate casting method. The plasticizers such as propylene glycol (PG) and dibutyl phthalate (DBP), and enhancers such as Span 20, Tween 20, sodium lauryl sulfate (SLS), isopropyl myristate (IPM) and ethanol (EtOH) were formulated in different concentrations in the patches. Such different combinations of polymer with various enhancers and plasticizers in patches were evaluated for their effect on the physicochemical properties and drug release behavior of flurbiprofen. The drug release study was carried out by the paddle-over-disk method and permeation of drug was performed by Franz diffusion cell using rabbit skin. Patches having ethanol with ethyl cellulose showed more uniformity in the physical properties while the smoothness and clarity of patches containing sodium lauryl sulfate were not satisfactory. The drug release from patches followed Higuchi and Korsmeyer-Pappas model while maximum drug release was obtained by isopropyl myristate (903 microg). It was concluded that the patches having ethyl cellulose with isopropyl myristate and propylene glycol are more useful for transdermal patches of flurbiprofen. PMID:25272649

Idrees, Arfat; Rahman, Nisar Ur; Javaid, Zeeshan; Kashif, Muhammad; Aslam, Irfan; Abbas, Khizar; Hussain, Talib

2014-01-01

283

Species differences in sinusoidal and canalicular efflux transport of mycophenolic acid 7-O-glucuronide in sandwich-cultured hepatocytes  

PubMed Central

Metabolism and sinusoidal/canalicular efflux of mycophenolic acid (MPA) was investigated using sandwich-cultured hepatocytes (SCHs). After applying MPA to SCHs from humans, wild-type rats, and multidrug resistance-associated protein (Mrp) 2-deficient rats, the MPA metabolites 7-O-glucuronide (MPAG) and acyl glucuronide (AcMPAG) were detected in the intracellular compartment of the SCHs. Sinusoidal efflux of MPAG was detected in all SCH preparations including Mrp2-deficient rat SCHs, whereas canalicular efflux of MPAG was observed in wild-type rat and human SCHs but not in Mrp2-deficient rat SCHs. The ratio of canalicular efflux to net (canalicular plus sinusoidal) efflux was 37 ± 8% in wild-type rat SCHs, while the ratio in human SCHs was significantly lower (20 ± 2%, P < 0.05), indicating species differences in the direction of hepatic MPAG transport. This 20% ratio in human SCHs corresponds to a high sinusoidal MPAG efflux (80%) that can in part account for the urine-dominated recovery of MPAG in humans. Both sinusoidal and canalicular MPAG efflux in rat SCHs shows a good correspondence to urinary and biliary recovery of MPAG after MPA dosing. The sinusoidal efflux of AcMPAG in human SCHs was detected from one out of three donors, suggesting donor-to-donor variation. In conclusion, this study demonstrates the predictive value of SCHs for elucidating the interplay of metabolism and efflux transport, in addition to demonstrating a species difference between rat and human in sinusoidal and canalicular efflux of MPAG. PMID:25505584

Tetsuka, Kazuhiro; Gerst, Nicolas; Tamura, Kouichi; Masters, Jeffrey N

2014-01-01

284

Pregnane-X-Receptor Controls Hepatic Glucuronidation During Pregnancy and Neonatal Development in Humanized UGT1 Mice  

PubMed Central

In humanized UDP glucuronosyltransferase-1 (hUGT1) mice that express the entire UGT1 locus, the maternal hepatic UGT1A genes are dramatically induced 12-14 days after conception. Steroid induction of the UGT1A1 gene indicates that xenobiotic sensors, such as the pregnane X receptor (PXR) and constitutive androstane receptor (CAR), may underlie the induction process. In contrast, neonatal hUGT1 mice display severe hyperbilirubinemia, with limited expression of the UGT1A genes. This study identifies PXR as both a positive and negative regulator of the UGT1A1 gene. Pregnancy hormones, in particular the glucocorticoids, target PXR as a positive regulator of human glucuronidation. Employing reverse genetics, where PXR has been genetically deleted, hUGT1/Pxr?/? mice show limited induction of the liver UGT1A genes during pregnancy, whereas the exact opposite occurs in newborn mice. Neonatal hUGT1 mice show delayed expression of hepatic UGT1A1 and are severely hyperbilirubinemic. However, in hUGT1/Pxr?/? mice, hyperbilirubinemia is greatly reduced due to induction of hepatic UGT1A1. Thus, PXR serves to repress UGT1A1 gene expression during development. Transcriptional silencing of the UGT1A1 gene was relieved in neonatal hUGT1 hepatocytes through interruption of PXR by small interfering RNA. Conclusion: PXR is a key regulator of pregnancy induced glucuronidation capacity in addition to modulating the severity of neonatal jaundice. (Hepatology 2012;56:658–667) PMID:22371261

Chen, Shujuan; Yueh, Mei-Fei; Evans, Ronald M; Tukey, Robert H

2012-01-01

285

40 CFR 721.3152 - Ethanaminium, N-ethyl-2-hydroxy-N,N-bis(2-hydroxyethyl)-, diester with C12-18 fatty acids, ethyl...  

Code of Federal Regulations, 2013 CFR

...C12-18 fatty acids, ethyl sulfates (salts). 721.3152 Section 721.3152...C12-18 fatty acids, ethyl sulfates (salts). (a) Chemical substance and significant...C12-18 fatty acids, ethyl sulfates (salts) (P-94-24) is subject to...

2013-07-01

286

Production of monoclonal antibody to herbicide fenoxaprop-ethyl.  

PubMed

Fenoxaprop-ethyl is a selective aryloxyphenoxypropionate herbicide used widely to control annual and perennial grasses. A monoclonal antibody (MAb) against fenoxaprop-ethyl (FE), designated as 3E6B9C, was produced and had very low cross-reactivity with some of its structural analogs, such as clodinafop-propargyl, diclofop-methyl, lactofen, and quizalofop-p-ethyl. An indirect competitive enzyme-linked immunosorbent assay (icELISA) was developed. The concentration of R-(+)-fenoxaprop-ethyl (R-FE) producing 50% of inhibition (IC(50)) and the working range of icELISA were 3.1?ng/mL and 0.6-29?ng/mL, respectively. This assay is also sensitive to R-fenoxaprop, S-(-)-fenoxaprop-ethyl, and metamifop with IC(50) of 3.4, 2.7, and 3.5?ng/mL, respectively. The recoveries of R-FE in soil samples with the icELISA were 86-102%. PMID:22008074

Cui, Yongliang; Nan, Tiegui; Tan, Guiyu; Li, Qing X; Wang, Baomin; Liu, Shangzhong

2011-10-01

287

Phosphate-solubilizing and plant-growth-promoting Pseudomonas aeruginosa PS1 improves greengram performance in quizalafop-p-ethyl and clodinafop amended soil.  

PubMed

The quizalafop-p-ethyl- and clodinafop-tolerant phosphate-solubilizing and plant-growth-promoting Pseudomonas aeruginosa PS1 isolated from the rhizospheric soils of mustard was used to determine its phosphate-solubilizing activity and other plant-growth-promoting traits both in the presence and absence of technical grade quizalafop-p-ethyl and clodinafop under in vitro conditions. Quizalafop-p-ethyl (at 40, 80, and 120 ppb) and clodinafop (at 400, 800, and 1200 ppb) reduced the P-solubilizing activity, synthesis of indole-3-acetic acid, and siderophores progressively with increasing concentrations of each herbicide. Hydrogen cyanide and ammonia synthesisized by this strain, however, did not change. Furthermore, the effects of three concentrations each of quizalafop-p-ethyl [40 (recommended dose), 80, and 120 ppb] and clodinafop [400 (recommended dose), 800, and 1200 ppb] were evaluated on plant-growth-promoting Pseudomonas aeruginosa strain PS1 inoculated greengram plants, grown in sandy clay loam soil. Generally, all of the concentrations of both quizalafop-p-ethyl and clodinafop showed phytotoxicity and severely affected the growth, symbiosis, grain yield, and nutrient uptake by greengram plants. The toxicity of quizalafop-p-ethyl and clodinafop enhanced gradually with the increase in the dose rate of herbicides. Quizalafop-p-ethyl was more toxic than clodinafop. In contrast, herbicide-tolerant P. aeruginosa strain PS1 when used with herbicides increased the measured parameters at all concentrations. Both quizalafop-p-ethyl at 120 ppb and clodinafop at 400 ppb increased total chlorophyll content, leghemoglobin, root N, shoot N, root P, shoot P, seed yield, and seed protein, relative to the uninoculated control. The study suggests that the phytotoxicity of herbicides to legumes could be reduced by applying the growth-promoting herbicide-tolerant strain of Pseudomonas aeruginosa PS1. PMID:19756846

Ahemad, Munees; Khan, Mohammad Saghir

2010-02-01

288

Carboxylic acid drug-induced DNA nicking in HEK293 cells expressing human UDP-glucuronosyltransferases: role of acyl glucuronide metabolites and glycation pathways.  

PubMed

Glucuronidation of carboxylic-acid-containing drugs can yield reactive acyl (ester-linked) glucuronide metabolites that are able to modify endogenous macromolecules. Previous research has shown that several carboxylic acid drugs are genotoxic in isolated mouse hepatocytes, and that DNA damage is prevented by the glucuronidation inhibitor, borneol. Whether these species induce comparable genetic damage in human cells is unknown. In this study, we investigated the mechanisms of clofibric acid-induced genotoxicity in HEK293 cells expressing the human UDP-glucuronosyltransferases UGT1A3, UGT1A9, or UGT2B7, and screened three other carboxylic acid drugs for UGT-dependent genotoxicity. DNA damage was detected using the alkaline version of the comet assay. HEK293 cells were incubated for 18 h with vehicle (2.5 mM NaOH), 0.1-2.5 mM clofibric acid or 0.1-1.0 mM benoxaprofen, bezafibrate, or probenecid. To identify mechanisms underlying any observed genotoxicity, we treated UGT2B7 transfectants with 10 mM aminoguanidine, 1 mM borneol, or 2 mM desferrioxamine mesylate prior to co-incubation with 1 mM clofibric acid for 18 h. Compared to vehicle, clofibric acid, benoxaprofen, and probenecid produced significant DNA damage in all three UGT-transfected HEK293 cell lines, detectable from the lowest concentration tested. Bezafibrate caused DNA damage only at higher concentrations (1.0 mM) in UGT2B7- and UGT1A9-, but not UGT1A3-transfected cells. No drug-induced DNA damage was detected in untransfected cells, consistent with the limited glucuronidation capacity of these cells. The glycation/glycoxidation inhibitor aminoguanidine and the glucuronidation inhibitor borneol significantly decreased clofibric-acid-mediated DNA damage in UGT2B7 transfected cells by 73.5 and 94.8%, respectively. The inhibitor of transition-metal-catalyzed oxidation, desferrioxamine mesylate, had no significant effect on DNA damage. This study demonstrates the substrate-dependent role of human UGTs in the bioactivation of carboxylic acid drugs to genotoxic acyl glucuronide metabolites that are able to damage nuclear DNA via glycation and/or glycoxidation mechanisms. PMID:17880178

Southwood, Hamish T; DeGraaf, Yvette C; Mackenzie, Peter I; Miners, John O; Burcham, Philip C; Sallustio, Benedetta C

2007-10-01

289

Fragrance material review on 2-(p-tolyloxy)ethyl acetate.  

PubMed

A toxicologic and dermatologic review of 2-(p-tolyloxy)ethyl acetate when used as a fragrance ingredient is presented. 2-(p-tolyloxy)ethyl acetate is a member of the fragrance structural group aryl alkyl alcohol simple acid esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for 2-(p-tolyloxy)ethyl acetate were evaluated, then summarized, and includes physical properties data. A safety assessment of the entire AAASAE will be published simultaneously with this document. Please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22414652

McGinty, D; Letizia, C S; Api, A M

2012-09-01

290

Deuterium kinetic isotopic study for hydrogenolysis of ethyl butyrate  

Microsoft Academic Search

The hydrogenation of ethyl butyrate, n-butyric acid, and n-butyraldehyde to their corresponding alcohol(s) has been studied over a ?-Al2O3-supported cobalt catalyst using a high-pressure fixed-bed reactor in the temperature range of 473–493K. H2–D2–H2 switching experiments show that ethyl butyrate and n-butyric acid follow an inverse kinetic isotope effect (KIE) (i.e. rH\\/rD=0.50–0.54), whereas n-butyraldehyde did not display any KIE (i.e. rH\\/rD=0.98).

Muthu Kumaran Gnanamani; Gary Jacobs; Robert A. Keogh; Burtron H. Davis

2011-01-01

291

Rotational spectrum of ethyl cyanoacetylene (C2H5C?C-C?N), a compound of potential astrochemical interest  

NASA Astrophysics Data System (ADS)

Context. New radiotelescopes, such as the very sensitive ALMA, will enable the detection of interstellar molecules in much lower concentrations than previously possible. A successful identification of an interstellar molecule requires that laboratory microwave and millimeter-wave spectra are investigated. Several cyanopolyynes and alkynylcarbonitriles have already been detected in the interstellar medium (ISM). Cyanoacetylene (HC?C-C?N) is abundant in the ISM and its methyl derivative, 2-butynenitrile (CH3C?C-C?N), is also present. The next derivative, ethyl cyanoacetylene, (2-pentynenitrile C2H5C?C-C?N) may also be present in interstellar space. Aims: We report the rotational spectrum of the ethyl cyanoacetylene (C2H5C?C-C?N). This is hoped to facilitate identifying gaseous ethyl cyanoacetylene in the ISM. Methods: We studied the rotational spectrum of C2H5C?C-C?N between 13 and 116 GHz with the microwave spectrometer of the University of Oslo. The spectroscopic study was augmented by high-level quantum-chemical calculations at B3LYP/cc-pVTZ and CCSD/cc-pVTZ levels of theory. Results: We present for the first time the rotational spectrum of the ethyl cyanoacetylene (C2H5C?C-C?N). We assigned 342 transitions of the vibrational ground state, accurate values were obtained for rotational and centrifugal distortion constants, and the dipole moment was determined as well.

Carles, S.; Møllendal, H.; Guillemin, J.-C.

2013-10-01

292

Communication: Substrate induced dehydrogenation: Transformation of octa-ethyl-porphyrin into tetra-benzo-porphyrin  

NASA Astrophysics Data System (ADS)

Individual molecules of octa-ethyl-porhphyrin-iron(III)-chloride adsorbed on a Cu(111) surface are studied by scanning tunneling microscopy. Upon moderate heating the molecules are found to transform into Fe-tetra-benzo-porphyrin at a surprisingly low temperature of 380 K. If the annealing is interrupted, the different steps of the transformation can be imaged. By evaluating the ratio of transformed molecules as function of annealing temperature, an approximate activation energy of 1.2 eV ± 0.1 eV could be determined.

van Vörden, D.; Lange, M.; Schmuck, M.; Schaffert, J.; Cottin, M. C.; Bobisch, C. A.; Möller, R.

2013-06-01

293

Evaluation of in situ generated valproyl 1-O-?-acyl glucuronide in valproic acid toxicity in sandwich-cultured rat hepatocytes.  

PubMed

Acyl glucuronides are reactive electrophilic metabolites implicated in the toxicity of carboxylic acid drugs. Valproyl 1-O-?-acyl glucuronide (VPA-G), which is a major metabolite of valproic acid (VPA), has been linked to the development of oxidative stress in VPA-treated rats. However, relatively little is known about the toxicity of in situ generated VPA-G and its contribution to VPA hepatotoxicity. Therefore, we investigated the effects of modulating the in situ formation of VPA-G on lactate dehydrogenase (LDH) release (a marker of necrosis), BODIPY 558/568 C12 accumulation (a marker of steatosis), and cellular glutathione (GSH) content in VPA-treated sandwich-cultured rat hepatocytes. VPA increased LDH release and BODIPY 558/568 C12 accumulation, whereas it had little or no effect on total GSH content. Among the various uridine 5'-diphospho-glucuronosyltransferase inducers evaluated, ?-naphthoflavone produced the greatest increase in VPA-G formation. This was accompanied by an attenuation of the increase in BODIPY 558/568 C12 accumulation, but did not affect the change in LDH release or total GSH content in VPA-treated hepatocytes. Inhibition of in situ formation of VPA-G by borneol was not accompanied by substantive changes in the effects of VPA on any of the toxicity markers. In a comparative study, in situ generated diclofenac glucuronide was not toxic to rat hepatocytes, as assessed using the same chemical modulators, thereby demonstrating the utility of the sandwich-cultured rat hepatocyte model. Overall, in situ generated VPA-G was not toxic to sandwich-cultured rat hepatocytes, suggesting that VPA glucuronidation per se is not expected to be a contributing mechanism for VPA hepatotoxicity. PMID:25147275

Surendradoss, Jayakumar; Chang, Thomas K H; Abbott, Frank S

2014-11-01

294

Interaction and transport characteristics of mycophenolic acid and its glucuronide via human organic anion transporters hOAT1 and hOAT3  

Microsoft Academic Search

The immunosuppressant mycophenolate mofetil (MMF) is frequently administered with calcineurin inhibitors and corticosteroids to recipients of organ transplantations. However, the renal handling of the active metabolite mycophenolic acid (MPA) and 7-O-MPA-glucuronide (MPAG) has been unclear. The purpose of the present study was to assess the interaction of MPA and MPAG with the human renal organic anion transporters hOAT1 (SLC22A6) and

Yuichi Uwai; Hideyuki Motohashi; Yoshie Tsuji; Harumasa Ueo; Toshiya Katsura; Ken-ichi Inui

2007-01-01

295

Quantification of glucuronidated and sulfated steroids in human urine by ultra-high pressure liquid chromatography quadrupole time-of-flight mass spectrometry  

Microsoft Academic Search

The urinary steroid profile is constituted by anabolic androgenic steroids, including testosterone and its relatives, that\\u000a are extensively metabolized into phase II sulfated or glucuronidated steroids. The use of liquid chromatography coupled to\\u000a mass spectrometry (LC-MS) is an issue for the direct analysis of conjugated steroids, which can be used as urinary markers\\u000a of exogenous steroid administration in doping analysis,

Flavia Badoud; Elia Grata; Julien Boccard; Davy Guillarme; Jean-Luc Veuthey; Serge Rudaz; Martial Saugy

2011-01-01

296

Quantification of phenolic acids and their methylates, glucuronides, sulfates and lactones metabolites in human plasma by LC-MS/MS after oral ingestion of soluble coffee.  

PubMed

Chlorogenic acids and derivatives like phenolic acids are potentially bioactive phenolics, which are commonly found in many foods. Once absorbed, chlorogenic and phenolic acids are highly metabolized by the intestine and the liver, producing glucuronidated and/or sulphated compounds. These metabolites were analyzed in human plasma using a validated liquid chromatography-electrospray ionization-tandem mass spectrometry (LC-ESI-MS/MS) method. After protein precipitation, phenolic acids and their metabolites were extracted by using ethanol and chromatographic separation was achieved by reversed-phase using an Acquity UPLC BEH C18 column combined with a gradient elution system using 1% acetic acid aqueous solution and 1% acetic acid with 100% acetonitrile. The method was able to quantify 56 different compounds including 24 phenolic acids, 4 lactones, 15 sulfates and 13 glucuronides metabolites between 5 and 1000nM in plasma for most of them, except for m-dihydrocoumaric acid, 5-ferulloylquinic-glucuronide, 4-methoxycinnamic acid, 3-phenylpropionic acid, 3-(4-methoxyphenyl)propionic acid (25 to 1000nM) and p-dihydrocoumaric acid (50-1000nM). Values of repeatability and intermediate reproducibility were below 15% of deviation in general, and maximum 20% for the lowest concentrations. The validated method was successfully applied to quantify phenolic acids and their metabolites in plasma obtained after oral ingestion of soluble coffee. In conclusion, the developed and validated method is proved to be very sensitive, accurate and precise for the quantification of these possible dietary phenols. PMID:24216280

Marmet, Cynthia; Actis-Goretta, Lucas; Renouf, Mathieu; Giuffrida, Francesca

2014-01-01

297

Comparison of pharmacokinetics of mycophenolic acid and its glucuronide between patients with lupus nephritis and with kidney transplantation.  

PubMed

The pharmacokinetics of mycophenolic acid (MPA) and its glucuronide (mycophenolic acid phenolic glucuronide, MPAG) in lupus nephritis (LN) have not been fully characterized. The aim of this study was to evaluate the pharmacokinetics of MPA and MPAG in LN patients by comparing the pharmacokinetics with those of kidney transplant (KT) recipients. Six LN patients (World Health Organization class IV and V) and 24 KT recipients [8 recipients treated with tacrolimus (Tac) and 16 with cyclosporine (CyA)] during the early posttransplantation period were enrolled. Pharmacokinetic parameters of MPA and MPAG were compared between LN patients and Tac-treated or CyA-treated KT recipients. The area under the concentration-time curve (AUC0-12) of MPA normalized to mycophenolate mofetil (MMF) dose (mg/kg) was significantly lower in LN patients and CyA-treated KT recipients than in Tac-treated KT recipients [median (range), 2.19 (0.87-4.23), 2.36 (1.13-5.74), and 4.86 (3.25-6.75) microg x h/mL per mg/kg, P < 0.05 and P < 0.01, respectively]. Dose-normalized MPAG AUC0-12 was significantly lower in LN patients and slightly lower in Tac-treated KT recipients than in CyA-treated KT recipients [median (range), 35.0 (8.34-69.8), 51.6 (34.4-94.8), and 84.1 (34.7-152) microg x h/mL per mg/kg, P < 0.05 and P = 0.13, respectively]. The ratio of MPA AUC5-12 to AUC0-12, an estimate of MPA enterohepatic recirculation, was slightly higher in LN patients and Tac-treated KT recipients than in CyA-treated KT recipients [median (range), 0.44 (0.35-0.56), 0.45 (0.42-0.61), and 0.34 (0.22-0.55), P = 0.29 and P = 0.10, respectively]. Serum creatinine was significantly lower in LN patients than in Tac-treated and CyA-treated KT recipients. In conclusion, the pharmacokinetics of MPA in LN patients is characterized by high MPA clearance and in CyA-treated KT recipients. Despite this higher clearance of MPA, MPAG AUC0-12 was lower in LN patients most likely due to better renal function in LN patients. PMID:18978521

Mino, Yasuaki; Naito, Takafumi; Matsushita, Tomomi; Otsuka, Atsushi; Ushiyama, Tomomi; Ozono, Seiichiro; Hishida, Akira; Kagawa, Yoshiyuki; Kawakami, Junichi

2008-12-01

298

40 CFR 721.10243 - Phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-, bis(2-chloroethyl) ester.  

Code of Federal Regulations, 2013 CFR

...false Phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-, bis...10243 Phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-, bis...identified as phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-,...

2013-07-01

299

40 CFR 721.10243 - Phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-, bis(2-chloroethyl) ester.  

Code of Federal Regulations, 2012 CFR

...false Phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-, bis...10243 Phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-, bis...identified as phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-,...

2012-07-01

300

40 CFR 721.10243 - Phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-, bis(2-chloroethyl) ester.  

Code of Federal Regulations, 2014 CFR

...false Phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-, bis...10243 Phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-, bis...identified as phosphonic acid, P-[2-[bis(2-hydroxyethyl)amino]ethyl]-,...

2014-07-01

301

Dissociation of the Ethyl Radical: An Exercise in Computational Chemistry  

ERIC Educational Resources Information Center

A set of exercises for use in a typical physical chemistry laboratory course are described, modeling the unimolecular dissociation of the ethyl radical to form ethylene and atomic hydrogen. Students analyze the computational results both qualitatively and quantitatively. Qualitative structural changes are compared to approximate predicted values…

Nassabeh, Nahal; Tran, Mark; Fleming, Patrick E.

2014-01-01

302

Synthesis and degradation behavior of poly(ethyl cyanoacrylate)  

Technology Transfer Automated Retrieval System (TEKTRAN)

Poly(ethyl cyanoacrylate) was synthesized using N, N'-dimethyl-p-toulidine (DMPT) as an initiator through anionic/zwitterionic pathway. The degradability and the degradation mechanism of the prepared polymers were carefully examined from various points of views. It was found that the polymers were...

303

Ethyl Methane Sulfonate Induces Morphological Mutations in Capsicum annuum  

Microsoft Academic Search

The present study was carried out to induce morphological mutations in Capsicum annuum cultivar Longhi. Seeds were subjected to different treatment levels of ethyl methane sulfonate (EMS). The treated and untreated plants were self-fertilized for two generations to observe different morphological characters in M3 generation. Several unique and interesting mutants were isolated in this investigation. These independent mutants have different

NYLA JABEEN; BUSHRA MIRZA

304

HEALTH AND ENVIRONMENTAL EFFECTS PROFILE FOR METHYL ETHYL BENZENES  

EPA Science Inventory

The Health and Environmental Effects Profile for Methyl Ethyl Benzenes was prepared by the Office of Health and Environmental Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH for the Office of Solid Waste to support listings of hazardous constituents of a ...

305

HEALTH AND ENVIRONMENTAL EFFECTS PROFILE FOR METHYL ETHYL KETONE  

EPA Science Inventory

The Health and Environmental Effects Profile for methyl ethyl ketone was prepared by the Office of Health and Environmental Assessment, Environmental Criteria and Assessment Office, Cincinnati, OH for the Office of Solid Waste and Emergency Response to support listings of hazardo...

306

40 CFR 180.441 - Quizalofop ethyl; tolerances for residues.  

Code of Federal Regulations, 2011 CFR

...established for the combined residues of the herbicide quizalofop (2-[4-(6-chloroquinoxalin-2-yl...established for the combined residues of the herbicide quizalofop (2-[4-(6-chloroquinoxalin-2-yl...established for the combined residues of the herbicide quizalofop-p ethyl ester...

2011-07-01

307

Kinetics of Ethyl Acetate Synthesis Catalyzed by Acidic Resins  

ERIC Educational Resources Information Center

A low-cost experiment to carry out the second-order reversible reaction of acetic acid esterification with ethanol to produce ethyl acetate is presented to illustrate concepts of kinetics and reactor modeling. The reaction is performed in a batch reactor, and the acetic acid concentration is measured by acid-base titration versus time. The…

Antunes, Bruno M.; Cardoso, Simao P.; Silva, Carlos M.; Portugal, Ines

2011-01-01

308

Recycling Solvent Mixtures of Ethyl Acetate and Hexanes  

NASA Astrophysics Data System (ADS)

A method to recycle ethyl acetate-hexanes mixtures from thin-layer or column chromatography experiments is described. The procedure consists of co-distillation of the mixture followed by estimation of the composition by reference to an Rf vs percent composite graph. The mixture is then diluted with the appropriate solvent to achieve the desired composition.

Wilkinson, Timothy J.

1998-12-01

309

Synthesis of Ethyl Nalidixate: A Medicinal Chemistry Experiment  

ERIC Educational Resources Information Center

A series of laboratory experiments that complement a medicinal chemistry lecture course in drug design and development have been developed. The synthesis of ethyl nalidixate covers three separate experimental procedures, all of which can be completed in three, standard three-hour lab classes and incorporate aspects of green chemistry such as…

Leslie, Ray; Leeb, Elaine; Smith, Robert B.

2012-01-01

310

The antiestrogen [2-(4-benzyl-phenoxy)ethyl]diethylammonium  

E-print Network

)ethyl]diethylammonium chloride, (I), is a diphenylmethane analogue of the antiestrogen tamoxifen which antagonizes the binding). A chemopotentiating effect of the drug in patients with early metastatic breast cancer has also been observed (Brandes & Bracken, 1998), and growth-inhibitory effects on human ovarian cancer cells when combined with cisplatin

311

46 CFR 151.50-40 - Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether.  

Code of Federal Regulations, 2013 CFR

...2013-10-01 false Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether. 151.50-40 Section...Requirements § 151.50-40 Additional requirements for carbon disulfide (carbon bisulfide) and ethyl...

2013-10-01

312

46 CFR 151.50-40 - Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether.  

Code of Federal Regulations, 2014 CFR

...2014-10-01 false Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether. 151.50-40 Section...Requirements § 151.50-40 Additional requirements for carbon disulfide (carbon bisulfide) and ethyl...

2014-10-01

313

46 CFR 151.50-40 - Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether.  

Code of Federal Regulations, 2012 CFR

...2012-10-01 false Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether. 151.50-40 Section...Requirements § 151.50-40 Additional requirements for carbon disulfide (carbon bisulfide) and ethyl...

2012-10-01

314

40 CFR 721.10109 - Hexanoic acid, 2-ethyl-, mixed triesters with benzoic acid and trimethylolpropane.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Hexanoic acid, 2-ethyl-, mixed triesters with benzoic acid and trimethylolpropane. 721.10109 Section...Chemical Substances § 721.10109 Hexanoic acid, 2-ethyl-, mixed triesters with...

2011-07-01

315

40 CFR 180.595 - Flufenpyr-ethyl; tolerances for residues.  

Code of Federal Regulations, 2013 CFR

...General. (1) Tolerances are established for residues of the herbicide, flufenpyr-ethyl; acetic acid, [2-chloro-4-fluoro-5...01 (2) Tolerances are established for residues of the herbicide flufenpyr-ethyl; acetic acid,...

2013-07-01

316

40 CFR 180.430 - Fenoxaprop-ethyl; tolerances for residues.  

Code of Federal Regulations, 2012 CFR

...General. Tolerances are established for residues of the herbicide fenoxaprop-ethyl, including its metabolites and...Time-limited tolerances are established for residues of the herbicide fenoxaprop-ethyl, including its...

2012-07-01

317

40 CFR 180.595 - Flufenpyr-ethyl; tolerances for residues.  

Code of Federal Regulations, 2012 CFR

...General. (1) Tolerances are established for residues of the herbicide, flufenpyr-ethyl; acetic acid, [2-chloro-4-fluoro-5...01 (2) Tolerances are established for residues of the herbicide flufenpyr-ethyl; acetic acid,...

2012-07-01

318

40 CFR 180.430 - Fenoxaprop-ethyl; tolerances for residues.  

Code of Federal Regulations, 2011 CFR

...General. Tolerances are established for residues of the herbicide fenoxaprop-ethyl, including its metabolites and...Time-limited tolerances are established for residues of the herbicide fenoxaprop-ethyl, including its...

2011-07-01

319

40 CFR 180.430 - Fenoxaprop-ethyl; tolerances for residues.  

Code of Federal Regulations, 2013 CFR

...General. Tolerances are established for residues of the herbicide fenoxaprop-ethyl, including its metabolites and...Time-limited tolerances are established for residues of the herbicide fenoxaprop-ethyl, including its...

2013-07-01

320

40 CFR 180.595 - Flufenpyr-ethyl; tolerances for residues.  

Code of Federal Regulations, 2011 CFR

...General. (1) Tolerances are established for residues of the herbicide, flufenpyr-ethyl; acetic acid, [2-chloro-4-fluoro-5...01 (2) Tolerances are established for residues of the herbicide flufenpyr-ethyl; acetic acid,...

2011-07-01

321

40 CFR 180.515 - Carfentrazone-ethyl; tolerances for residues.  

Code of Federal Regulations, 2012 CFR

...515 Carfentrazone-ethyl; tolerances for residues. (a) General. Tolerances are established for residues of the herbicide carfentrazone-ethyl, including its metabolites and degradates, in or on the commodities listed in the following...

2012-07-01

322

40 CFR 180.595 - Flufenpyr-ethyl; tolerances for residues.  

Code of Federal Regulations, 2014 CFR

...General. (1) Tolerances are established for residues of the herbicide, flufenpyr-ethyl; acetic acid, [2-chloro-4-fluoro-5...01 (2) Tolerances are established for residues of the herbicide flufenpyr-ethyl; acetic acid,...

2014-07-01

323

40 CFR 180.595 - Flufenpyr-ethyl; tolerances for residues.  

Code of Federal Regulations, 2010 CFR

...General. (1) Tolerances are established for residues of the herbicide, flufenpyr-ethyl; acetic acid, [2-chloro-4-fluoro-5...01 (2) Tolerances are established for residues of the herbicide flufenpyr-ethyl; acetic acid,...

2010-07-01

324

40 CFR 721.10109 - Hexanoic acid, 2-ethyl-, mixed triesters with benzoic acid and trimethylolpropane.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Hexanoic acid, 2-ethyl-, mixed triesters with benzoic acid and trimethylolpropane. 721.10109 Section...Chemical Substances § 721.10109 Hexanoic acid, 2-ethyl-, mixed triesters with...

2010-07-01

325

46 CFR 151.50-40 - Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether.  

Code of Federal Regulations, 2011 CFR

...2011-10-01 false Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether. 151.50-40 Section...Requirements § 151.50-40 Additional requirements for carbon disulfide (carbon bisulfide) and ethyl...

2011-10-01

326

46 CFR 151.50-40 - Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether.  

Code of Federal Regulations, 2010 CFR

...2010-10-01 false Additional requirements for carbon disulfide (carbon bisulfide) and ethyl ether. 151.50-40 Section...Requirements § 151.50-40 Additional requirements for carbon disulfide (carbon bisulfide) and ethyl...

2010-10-01

327

40 CFR 721.9514 - Ethyl silicate, reaction products with modified alkoxysilane salt (generic).  

Code of Federal Regulations, 2013 CFR

...New Uses for Specific Chemical Substances § 721.9514 Ethyl silicate, reaction products with modified...generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...as Ethyl silicate, reaction products with...

2013-07-01

328

40 CFR 721.9514 - Ethyl silicate, reaction products with modified alkoxysilane salt (generic).  

Code of Federal Regulations, 2011 CFR

...New Uses for Specific Chemical Substances § 721.9514 Ethyl silicate, reaction products with modified...generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...as Ethyl silicate, reaction products with...

2011-07-01

329

40 CFR 721.9514 - Ethyl silicate, reaction products with modified alkoxysilane salt (generic).  

Code of Federal Regulations, 2012 CFR

...New Uses for Specific Chemical Substances § 721.9514 Ethyl silicate, reaction products with modified...generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...as Ethyl silicate, reaction products with...

2012-07-01

330

40 CFR 721.9514 - Ethyl silicate, reaction products with modified alkoxysilane salt (generic).  

Code of Federal Regulations, 2010 CFR

...New Uses for Specific Chemical Substances § 721.9514 Ethyl silicate, reaction products with modified...generic). (a) Chemical substance and significant...reporting. (1) The chemical substance identified...as Ethyl silicate, reaction products with...

2010-07-01

331

Determinants  

NSDL National Science Digital Library

Created by Lewis Blake and Stephanie Fitchett of the Connected Curriculum Project, the purposes of this module are to explore the properties of determinants of matrices and to develop an important theoretical formula. This is part of a larger collection of material hosted by Duke University.

Blake, Lewis

332

Homo- and hetero-dimerization of human UDP-glucuronosyltransferase 2B7 (UGT2B7) wild type and its allelic variants affect zidovudine glucuronidation activity.  

PubMed

Most human UDP-glucuronosyltransferase (UGT; EC 2.4.1.17) genes contain non-synonymous single nucleotide polymorphisms (nsSNPs) which cause amino acid substitutions. Allelic variants caused by nsSNPs may exhibit absent or reduced enzyme activity. UGT2B7 is one of the most important UGTs that glucuronidates abundant endobiotics and xenobiotics, such as estriol, morphine, and anticancer drugs. Three nsSNPs, UGT2B7*71S (211G>T), UGT2B7*2 (802C>T) and UGT2B7*5 (1192G>A) are observed in the UGT2B7 gene, and they code for allozymes UGT2B7*71S (A71S), UGT2B7*2 (H268Y), and UGT2B7*5 (D398N). UGT2B7 has been observed to form oligomers that affect its enzymatic activity and in this study, we investigated protein-protein interactions among UGT2B7 allozymes wild type (WT), A71S, H268Y and D398N, by performing a systematic quantitative fluorescence resonance energy transfer (FRET) analysis in combination with co-immunoprecipitation assay. Quantitative FRET analysis revealed that UGT2B7 allozymes formed homo- and hetero-dimers and showed distinct features in donor-acceptor distances. Both codon 71 and codon 268 in the N-terminal domain were involved in the dimeric interaction. Co-immunoprecipitation experiments also proved that UGT2B7 allozymes formed stable dimers. The glucuronidation activities of homo- and hetero-dimers were further tested with zidovudine as the substrate. An increase in activity was observed when WT hetero-dimerized with A71S compared with homo-dimers, while both H268Y and D398N impaired the activity of WT and A71S by forming hetero-dimers. In addition, zidovudine glucuronidation activity is associated with FRET distance. These findings provide insights into the consequences of amino acid substitution in UGT2B7 on zidovudine glucuronidation and the association between protein-protein interaction and glucuronidation activity. PMID:25770680

Yuan, Lingmin; Qian, Sainan; Xiao, Yongsheng; Sun, Hongying; Zeng, Su

2015-05-01

333

Activity coefficients at infinite dilution of organic solutes in the ionic liquid 1-ethyl-3-methylimidazolium methanesulfonate  

Microsoft Academic Search

Infinite dilution activity coefficients ?1? and gas–liquid partition coefficients KL of 30 selected hydrocarbons, alcohols, ketones, ethers, esters, haloalkanes, nitrogen- and sulphur-containing compounds in the ionic liquid (IL) 1-ethyl-3-methylimidazolium methanesulfonate [EMIM][MeSO3] were determined by gas–liquid chromatography at five temperatures in the range from 318.15 to 353.15K. Relative contribution of adsorption at gas–liquid interphase to the overall solute retention, as examined

Aleš Blahut; Marek Sobota; Vladimír Dohnal; Pavel Vrbka

2010-01-01

334

Detection of Benzene, Toluene, Ethyl Benzene, and Xylenes (BTEX) Using Toluene Dioxygenase-Peroxidase Coupling Reactions  

E-print Network

Detection of Benzene, Toluene, Ethyl Benzene, and Xylenes (BTEX) Using Toluene Dioxygenase, whole-cell bioassay for the detection of bioavailable benzene, toluene, ethyl benzene, and xylenes (BTEX of the response obtained from the blank) of 10, 10, 20, and 50 µM was observed for benzene, toluene, ethyl benzene

Chen, Wilfred

335

Direct Catalytic Asymmetric Aldol-Type Reaction of Aldehydes with Ethyl  

E-print Network

Direct Catalytic Asymmetric Aldol-Type Reaction of Aldehydes with Ethyl Diazoacetate Wengang Yao of aldehydes with ethyl diazoacetate catalyzed by the chiral complex of BINOL derivatives-Zr(OtBu)4 gave developed.2 We have recently developed a DBU-catalyzed aldol-type condensation of aldehydes with ethyl

Wang, Jianbo

336

40 CFR 721.10064 - 2-Propenoic acid, 2-[2-(ethenyloxy)ethoxy]ethyl ester.  

Code of Federal Regulations, 2010 CFR

...2-[2-(ethenyloxy)ethoxy]ethyl ester. 721.10064 Section 721.10064...2-[2-(ethenyloxy)ethoxy]ethyl ester. (a) Chemical substance and significant...2-[2-(ethenyloxy)ethoxy]ethyl ester (PMN P-04-909; CAS No....

2010-07-01

337

p-Terphenyl O-?-glucuronides, DNA topoisomerase inhibitors from Streptomyces sp. LZ35?gdmAI.  

PubMed

The analysis of genome sequence indicated that Streptomyces sp. LZ35 has the potential of producing many types of secondary metabolites, including p-terphenyls and geldanamycins. The fermentation of LZ35 in laboratory produces geldanamycins as the major components, which hampers the isolation of minor compounds. To clean the background of geldanamycins, the mutant strain LZ35?gdmAI of Streptomyces sp. LZ35 was constructed by disrupting the first PKS module of geldanamycin gene cluster (gdm). From this mutant, five novel p-terphenyls bearing glucuronic acid moiety, namely echosides A-E (1-5), were isolated with the aid of chromophore-guided fractionation. The structures of 1-5 were elucidated by the analysis of their HR-ESI-MS and NMR spectroscopic data. DNA relaxation assay indicated that compound 1 had evident inhibitory activity against topoisomerase I. Moreover, the inhibitory activity of compound 3 against topoisomerase II? is approximately equal to VP16, indicating that p-terphenyl O-?-glucuronides are promising leads for the development of novel inhibitors of topoisomerases. PMID:24507923

Deng, Jingjing; Lu, Chunhua; Li, Shanren; Hao, Huilin; Li, Zhenyu; Zhu, Jing; Li, Yaoyao; Shen, Yuemao

2014-03-01

338

Derivatization followed by gas chromatography-mass spectrometry for quantification of ethyl carbamate in alcoholic beverages.  

PubMed

A sensitive and rapid analytical methodology based on derivatization followed by gas chromatography-mass spectrometry (GC-MS) was developed for the quantitative determination of the toxic contaminant ethyl carbamate (EC, urethane, C(2)H(5)OCONH(2)) in alcoholic samples. EC was extracted using liquid-liquid extraction technique, and then silylated with bis-(trimethylsilyl)trifluoroacetamide, analysed finally by GC-MS. The isopropyl carbamate was used as the internal standard for quantitative analysis of EC in alcoholic samples. In this work, the sample extraction and derivatization reaction conditions were investigated, and the optimal extraction conditions obtained were: pH 9 and solvent of ethyl acetate, and the derivatization conditions were: derivatization reaction temperature of 80°C and time duration of 30 min. With the optimal conditions, the method validations were also studied. In the validation studies, EC exhibited good linearity with a regression coefficient of 0.9999. The limit of detection and limit of quantification were 0.30 and 5.0 ?g/kg, respectively. The precision was less than 8.4%. Finally, the proposed technique was successfully applied to the analysis of EC in 35 kinds of alcoholic samples. The experimental results have demonstrated that the proposed technique is a fast, reliable and low-cost method for determination of EC in alcoholic samples. PMID:22383421

Xu, Xuejiao; Gao, Yihan; Cao, Xiujun; Wang, Xiang; Song, Guoxin; Zhao, Jianfeng; Hu, Yaoming

2012-04-01

339

A rapid and sensitive assay to quantify valproyl 1-O-acyl glucuronide in supernatants of sandwich-cultured rat hepatocytes using ultra-high performance liquid chromatography-tandem mass spectrometry.  

PubMed

A rapid and sensitive ultra-high performance liquid chromatography-tandem mass spectrometry (UHPLC-MS/MS) method was developed and validated for the determination of valproyl-1-O-acyl glucuronide (VPA-G) levels in hepatocyte culture medium. Chromatographic separation was achieved using a Waters Acquity UPLC(®) BEH C18 column (1.7?m, 2.1mm×50mm) with gradient elution and a total run time of 4min. [(2)H6]-VPA-G was used as internal standard (IS). Quantification was performed in the multiple reaction monitoring (MRM) mode using the total ion current of the MRM transition pairs m/z 319.1?142.7 and m/z 319.1?175.2 for VPA-G, and m/z 325.1?149.3 and m/z 325.1?174.9 for the IS under negative electrospray ionization mode. The assay was linear over the VPA-G concentrations of 0.5-500ng/mL, with a r(2) value of 0.995±0.002 (mean±SD). The intra- and inter-day accuracy (% deviation) ranged from -10.2% to 11.1%, whereas the intra- and inter-day precision (% RSD) were ?7.43%. The method was applied successfully to the quantification of VPA-G levels in culture supernatants of sandwich-cultured rat hepatocytes treated with valproic acid (VPA). No significant difference in the levels of VPA-G over a culture period of 6 days was observed in an experiment that investigated the effect of the age of hepatocyte culture on the extent of VPA glucuronidation. The method presented here for the direct quantification of VPA-G is an improvement of existing methods in the literature and offers a shorter run time and greater sensitivity that enables the use of small volumes of sample. To the best of our knowledge, this is the first validated UHPLC-MS/MS method applied to the quantification of VPA-G in cell culture supernatants. PMID:23827518

Surendradoss, Jayakumar; Szeitz, András; Teng, Xiao Wei; Chang, Thomas K H; Abbott, Frank S

2013-08-01

340

Detailed chemical kinetic mechanisms of ethyl methyl, methyl tert-butyl and ethyl tert-butyl ethers: The importance of uni-molecular elimination reactions  

Microsoft Academic Search

A reaction mechanism of ethyl methyl ether (EME), methyl tert-butyl ether (MTBE) and ethyl tert-butyl ether (ETBE) for pyrolysis and oxidation have been constructed using the same method applied to di-ethyl ether (DEE) in our recent work [1]. The mechanism, comprising of 1051 reactions involving 215 species, was tested against the experimental data obtained using shock tubes with good agreement.

K. Yasunaga; J. M. Simmie; H. J. Curran; T. Koike; O. Takahashi; Y. Kuraguchi; Y. Hidaka

2011-01-01

341

1,3-Diferuloyl-sn-glycerol from the biocatalytic transesterification of ethyl 4-hydroxy-3-methoxy cinnamic acid (ethyl ferulate) and soybean oil.  

PubMed

1,3-Diferuloyl-sn-glycerol is found ubiquitously throughout the plant kingdom, possessing ultraviolet adsorbing and antioxidant properties. Diferuloyl glycerol was synthesized and isolated as a byproduct in up to 5% yield from a pilot plant scale packed-bed, biocatalytic transesterification of ethyl ferulate with soybean oil or mono- and diacylglycerols from soybean oil. The yield of the diferuloyl glycerol byproduct was directly proportional to the overall water concentration of the bioreactor. The isolated diferuloyl glycerol exhibited good ultraviolet adsorbing properties, 280-360 nm with a lambda(max) 322 nm, and compared well to the efficacy of commercial sunscreen active ingredients. The antioxidant capacity of diferuloyl glycerol (0.25-2.5 mM) was determined by its ability to scavenge 2,2-diphenyl-1-picrylhydrazyl radicals and was comparable to that of ferulic acid. At current pilot plant scale production capacity, 120 kg diferuloyl glycerol byproduct could be isolated per year. PMID:19238329

Compton, David L; Laszlo, Joseph A

2009-06-01

342

Theoretical and kinetic study of the hydrogen atom abstraction reactions of ethyl esters with hydrogen radicals  

NASA Astrophysics Data System (ADS)

Ab initio and chemical kinetic study of the hydrogen abstraction reactions by the hydrogen radical on ethyl formate, ethyl acetate, ethyl propanoate, and ethyl butanoate have been performed at the CCSD(T)/CBS//B3LYP/6-311G(d, p) level of theory. High-pressure limit rate constants at temperatures from 300 to 2500 K have been calculated for all of the reaction channels using transition state theory with Eckart tunneling corrections, and the data are fitted to the modified three parameters Arrhenius expression using least-squares regression. A branching ratio analysis for each reaction site has also been investigated for all of the ethyl esters.

Wang, Quan-De; Wang, Xing-Jian; Liu, Zi-Wu; Kang, Guo-Jun

2014-11-01

343

Spectroscopic Characterization and Detection of Ethyl Mercaptan in Orion  

NASA Astrophysics Data System (ADS)

New laboratory data of ethyl mercaptan, CH3CH2SH, in the millimeter- and submillimeter-wave domains (up to 880 GHz) provided very precise values of the spectroscopic constants that allowed the detection of gauche-CH3CH2SH toward Orion KL. This identification is supported by 77 unblended or slightly blended lines plus no missing transitions in the range 80-280 GHz. A detection of methyl mercaptan, CH3SH, in the spectral survey of Orion KL is reported as well. Our column density results indicate that methyl mercaptan is sime 5 times more abundant than ethyl mercaptan in the hot core of Orion KL. This work was based on observations carried out with the IRAM 30 m telescope. IRAM is supported by INSU/CNRS (France), MPG (Germany), and IGN (Spain).

Kolesniková, L.; Tercero, B.; Cernicharo, J.; Alonso, J. L.; Daly, A. M.; Gordon, B. P.; Shipman, S. T.

2014-03-01

344

Immune functions in methyl and ethyl carbamate treated mice.  

PubMed Central

Female B6C3F1 hybrid mice (5-7 weeks of age) were given methyl or ethyl carbamate over a 2 week period and subsequently examined for alterations in various immunological parameters. Exposure to methyl carbamate, a non-carcinogen, did not cause any alterations in the parameters examined. In contrast, exposure to the multipotential carcinogen, ethyl carbamate (urethan) at tumourigenic dosages caused severe myelotoxicity at all dosage levels. Related to the myelotoxicity was a marked depression of natural killer cell activity. Other parameters including susceptibility to tumour cell challenge, humoral immunity, cellular immunity and macrophage function were less affected. These studies indicate that non-toxic, but carcinogenic dosages of urethan, have profound but selective effects on the immune system which can be related to alterations in bone marrow functions. PMID:6983408

Luster, M I; Dean, J H; Boorman, G A; Dieter, M P; Hayes, H T

1982-01-01

345

Elevated plasma creatinine due to creatine ethyl ester use.  

PubMed

Creatine is a nutritional supplement widely used in sport, physical fitness training and bodybuilding. It is claimed to enhance performance. We describe a case in which serum creatinine is elevated due to the use of creatine ethyl esther. One week after withdrawal, the plasma creatinine had normalised. There are two types of creatine products available: creatine ethyl esther (CEE) and creatine monohydrate (CM). Plasma creatinine is not elevated in all creatine-using subjects. CEE , but not CM, is converted into creatinine in the gastrointestinal tract. As a result the use of CEE may be associated with elevated plasma creatinine levels. Since plasma creatinine is a widely used marker for renal function, the use of CEE may lead to a false assumption of renal failure. PMID:21411845

Velema, M S; de Ronde, W

2011-02-01

346

Preparation of ethyl magnesium bromide for regiospecific analysis of triacylglycerols.  

PubMed

This paper presents a procedure for preparation of a Grignard reagent, ethyl magnesium bromide, used for partial deacylation of triacylglycerols (TAG) in their regiospecific analysis. Magnesium turnings were reacted with ethereal solution of bromoethane in a screw-capped test tube to synthesize 2 mL of 1 M ethyl magnesium bromide. Continuously stirred with a vortex mixer, the reaction smoothly proceeded at room temperature. Regiospecific analysis of 1,3-distearoyl-2-oleoylglycerol using this product showed that fatty acid compositions of the sn-1(3) and sn-2 positions were contaminated by less than 2 mol% of fatty acids migrated from isomeric positions. The analyses of lard and cod liver/mackerel oil TAG showed typical distribution patterns of 16:0, 22:5n-3 and 22:6n-3 in pig and fish depot TAG. These results confirmed the view that the freshly prepared reagent is usable for regiospecific analysis of TAG. PMID:18622130

Ando, Yasuhiro; Tomita, Yuki; Haba, Yusuke

2008-01-01

347

The effects of pH on the enzymatic formation of ?-glucuronides of various retinoids by induced and noninduced microsomal UDPGA-glucuronosyltransferases of several rat tissues in vitro 1 1 Abbreviations used: acitretin, 9-(2?,3?,6? trimethyl, 4?methoxybenzyl1?) 3,7 dimethyl, nona-2,4,6,8 tetraenoic acid; acitretin-G, acitretin-glucuronide; BHT, butylated hydroxytoluene; CD367, tetramethyl, tetrahydro-anthracenyl-benzoic acid; CD367-G, CD367 glucuronide; HPLC, high-performance liquid chromatography; 3MC, 3-methylcholanthrene; MES, 2-[N-morpholino]ethanesulfonic acid; NEM, N-ethylmaleimide; 4-oxo-RA, 4-oxoretinoic acid; 4-oxo-RAG, 4-oxoretinoyl ?-glucuronide; RA, retinoic acid; RAG, retinoyl ?-glucuronide; RAR, retinoic acid receptor; ROL, retinol; RXR, retinoid X receptor; Tris, tris [hydroxymethyl] aminomethane; TTNPB, tetramethyl, tetrahydronaphthenyl-propenyl-benzoic acid; TTNPB-G, TTNPB glucuronide; UDPGA, UDP-glucuronic acid; UGT, UDPGA-glucuronosyl transferase  

Microsoft Academic Search

All-trans retinoyl-?-glucuronide, a prominent water-soluble metabolite of all-trans retinoic acid (RA) in animals, is formed by the enzymic transfer of the glucuronyl moiety of uridine diphosphoglucuronic acid to RA. Uridine diphosphoglucuronic acid glucuronosyl transferases (UGTs) of microsomal preparations catalyze this reaction. In noninduced rat liver microsomes, maximal activity was observed in the physiologic range (pH 6.9–7.5) for all-trans-RA, 9-cis-RA, all-trans-4-oxo-RA,

Giuseppe Genchi; Arun B Barua; Wei Wang; Wayne R Bidlack; James A Olson

1998-01-01

348

Hydrolysis of ethyl acetate:a pervaporation study  

Microsoft Academic Search

The influence of temperature on the separation factor, diffusion process, permeation rate, and permeability coefficient (k) for hydrolysis of ethyl acetate using a standard poly(vinyl alcohol) (PVA) membrane by pervaporation was investigated. The preliminary data presented in this work was obtained using a simple pervaporation technique built in-house. The experiments were conducted at 80, 65, 50 and 35°C. The initial

Habib I. Shaban

1998-01-01

349

Ethyl carbamate levels resulting from azodicarbonamide use in bread  

Microsoft Academic Search

Azodicarbonamide (ADA), a dough conditioner, is an additive approved in the US up to a maximum of 45 mg\\/kg in flour. The addition of 45 mg\\/kg of ADA was investigated and found to increase the ethyl carbamate (EC) content of commercially prepared breads by 1–3 ?g\\/kg. A similar increase in EC was observed in breads baked in the laboratory with

Benjamin J. Cañas; Gregory W. Diachenko; Patricia J. Nyman

1997-01-01

350

Enantioselective hydrogenation of ethyl acetoacetate on asymmetric Raney Ni catalysts  

SciTech Connect

The properties of Raney nickel catalysts modified by (+)-tartaric acid and active in enantioselective hydrogenation of ethyl acetoacetate depend on the chemical and phase compositions of the starting Ni-Al alloys. A decrease of the Ni content in the Ni-Al alloy specimens which corresponds to an increase of the fraction of the NiAl/sub 3/ intermetallic compound in them contributes to an increase of the catalytic activity and enantioselectivity of the action of the obtained catalysts.

Zubareva, N.D.; Chernysheva, V.V.; Grigor'ev, Yu.A.; Klabunovskii, E.I.

1987-09-10

351

Development of a hybrid fermentation-enzymatic bioprocess for the production of ethyl lactate from dairy waste.  

PubMed

This work explores the potential for the development of a hybrid fermentation-enzymatic process for the production of ethyl lactate from dairy waste. Cheese whey was used in Kluyveromyces marxianus and Lactobacillus bulgaricus batch cultures to produce ethanol and lactic acid respectively. Subsequently, the fermentation products were transferred into an organic phase through liquid-liquid extraction and ethyl lactate was formed in an esterification reaction catalyzed by lipases. The production of ethanol and lactic acid achieved under different conditions was 23gL(-1) and 29gL(-1), respectively. Furthermore, the efficiency of various organic solvents for the esterification reaction was evaluated and toluene was chosen for application in the process. The effect of water content was determined aiming to maximize the product yield and 40mgml(-1) was the optimal enzyme concentration. The bioprocess achieved maximum conversion of 33% constituting a valuable alternative to the application of energy demanding chemically derived methods. PMID:24785788

Koutinas, Michalis; Menelaou, Maria; Nicolaou, Evrydiki N

2014-08-01

352

Fragrance material review on ethyl phenyl carbinyl acetate.  

PubMed

A toxicologic and dermatologic review of ethyl phenyl carbinyl acetate when used as a fragrance ingredient is presented. Ethyl phenyl carbinyl acetate is a member of the fragrance structural group Aryl Alkyl Alcohol Simple Acid Esters (AAASAE). The AAASAE fragrance ingredients are prepared by reacting an aryl alkyl alcohol with a simple carboxylic acid (a chain of 1-4 carbons) to generate formate, acetate, propionate, butyrate, isobutyrate and carbonate esters. This review contains a detailed summary of all available toxicology and dermatology papers that are related to this individual fragrance ingredient and is not intended as a stand-alone document. Available data for ethyl phenyl carbinyl acetate were evaluated, then summarized, and includes: physical properties; acute toxicity; skin irritation; and skin sensitization data. A safety assessment of the entire AAASAE will be published simultaneously with this document; please refer to Belsito et al. (2012) for an overall assessment of the safe use of this material and all AAASAE in fragrances. PMID:22433983

McGinty, D; Letizia, C S; Api, A M

2012-09-01

353

FATTY ACID ETHYL ESTERS: QUANTITATIVE BIOMARKERS FOR MATERNAL ALCOHOL CONSUMPTION  

PubMed Central

Objective To develop a laboratory marker to identify newborns exposed to alcohol. Study design Meconium was collected from 30 infants from Jordan who were unexposed and from 248 Cleveland study infants of varying exposure status. Retrospective maternal alcohol histories were obtained. Fatty acid ethyl esters (FAEEs) were quantified with gas chromatography/flame ionization and compared between abstainers and non-abstainers to identify FAEEs of interest. The area under the receiver operating characteristic curve, sensitivity, specificity, and positive and negative predictive values were calculated by using definitions of drinking obtained from a graphical representation. Results Six of 7 FAEEs were significantly different between the non-abstainers and at least 1 of 2 of the abstaining groups. FAEEs best predicted drinks per drinking day, and ethyl linoleate had the greatest area under the curve (76%), with a sensitivity rate of 88%, a specificity rate of 64%, a positive predictive value of 9%, and a negative predictive value of 99%. No combination of FAEEs was better than a single ester for identifying drinkers. Conclusion Ethyl linoleate in meconium is a useful biological marker for identifying infants not exposed in utero to high levels of alcohol in a high-risk, substance-abusing, clinic-based sample. PMID:15973326

Bearer, Cynthia F.; Santiago, Luis Manuel; O’Riordan, Mary Ann; Buck, Kevin; Lee, Siemay C.; Singer, Lynn T.

2014-01-01

354

Sensory reception of the primer pheromone ethyl oleate  

NASA Astrophysics Data System (ADS)

Social work force distribution in honeybee colonies critically depends on subtle adjustments of an age-related polyethism. Pheromones play a crucial role in adjusting physiological and behavioral maturation of nurse bees to foragers. In addition to primer effects of brood pheromone and queen mandibular pheromone—both were shown to influence onset of foraging—direct worker-worker interactions influence adult behavioral maturation. These interactions were narrowed down to the primer pheromone ethyl oleate, which is present at high concentrations in foragers, almost absent in young bees and was shown to delay the onset of foraging. Based on chemical analyses, physiological recordings from the antenna (electroantennograms) and the antennal lobe (calcium imaging), and behavioral assays (associative conditioning of the proboscis extension response), we present evidence that ethyl oleate is most abundant on the cuticle, received by olfactory receptors on the antenna, processed in glomeruli of the antennal lobe, and learned in olfactory centers of the brain. The results are highly suggestive that the primer pheromone ethyl oleate is transmitted and perceived between individuals via olfaction at close range.

Muenz, Thomas S.; Maisonnasse, Alban; Plettner, Erika; Le Conte, Yves; Rössler, Wolfgang

2012-05-01

355

Microsomal metabolism of N-benzyl-N-ethylaniline and N-benzyl-N-ethyl-p-toluidine.  

PubMed

The in vitro hepatic microsomal metabolism of two tertiary anilines, N-benzyl-N-ethylaniline (NBNEA) and N-benzyl-N-ethyl-p-toluidine (NBNEPT), was examined in order to determine whether these compounds produce amide derivatives (benzoyl or acetyl) in addition to N-dealkylation and N-oxidation products as metabolites. The preparation of these tertiary anilines and their corresponding potential metabolites was undertaken. The amines and metabolites were separated using TLC and HPLC. Incubations were performed using hamster microsomal preparations fortified with NADPH. The substrates and their potential metabolites were extracted into dichloromethane and examined by TLC and HPLC. The metabolic process of particular interest was the formation of amides from NBNEA and NBNEPT. The results from these experiments indicated that neither tertiary aniline (NBNEA and NBNEPT) produced amide (acetyl or benzoyl) or N-oxide metabolites. These substrates were dealkylated to the corresponding secondary amines via debenzylation and de-ethylation. Uncharacterised metabolites observed with substrates are proposed to be phenolic (for NBNEA) and hydroxymethyl (for NBNEPT). These findings support the concept that: nitrones are essential intermediates for the formation of amides from secondary aromatic amines (chemical rearrangement to amide via an oxaziridine intermediate); carbinolamines produced by NBNEA and NBNEPT are not stable enough to allow further oxidation to amides and therefore these intermediates are broken down to dealkylated products. The results are discussed in relation to the mechanism of metabolic amide formation from amines. PMID:9893739

Ulgen, M; Ozer, U; Kucukguzel, I; Gorrod, J W

1997-01-01

356

Effects of wildlife of ethyl and methyl parathion applied to California USA rice fields  

USGS Publications Warehouse

Selected rice fields on the Sacramento National Wildlife Refuge Complex were aerially sprayed one time during May or June 1982 with either ethyl (0.11 kg Al/ha) or methyl (0.84 kg AI/ha) parathion for control of tadpole shrimp, Triops longicaudatus. No sick or dead vertebrate wildlife were found or adjacent to the treated rice fields after spraying. Specimens of the following birds and mammals were assayed for brain cholinesterase (ChE) activity to determine exposure to either form of parathion; house mouse, Mus musculus; black-tailed jackrabbit, Lepus californicus; mallard, Anas platyrhynchos; ring-necked pheasant, Phasianus colchicus; American coot, Fulica americana; and red-winged blackbird, Agelaius phoeniceus. Both mice and pheasants from methyl parathion-treated fields had overall mean ChE activities that were significantly (P < 0.05) inhibited compared with controls, and 7, 40, 54 and 57% of individual blackbirds, pheasant, mice, and coots, respectively, had inhibited brain ChE activities (i.e., less than -2 SD of control mean). Although no overall species effect was detected for ethyl parathoid treatment, pheasants (43%), coots (33%), and mice (37%) had significantly inhibited brain ChE activities. Neither of the parathion treatment appeared acutely hazardous to wildlife in or adjacent to rice fields, but sufficient information on potential hazards was obtained to warrant caution in use of these chemicals, especially methyl parathion, in rice fields.

Custer, T.W.; Hill, E.F.; Ohlendorf, H.M.

1985-01-01

357

Effects on wildlife of ethyl and methyl parathion applied to California rice fields  

USGS Publications Warehouse

Selected rice fields on the Sacramento National Wildlife Refuge Complex were aerially sprayed one time during May or June 1982 with either ethyl (0.11 kg Al/ha) or methyl (0.84 kg AI/ha) parathion for control of tadpole shrimp, Triops longicaudatus. No sick or dead vertebrate wildlife were found or adjacent to the treated rice fields after spraying. Specimens of the following birds and mammals were assayed for brain cholinesterase (ChE) activity to determine exposure to either form of parathion; house mouse, Mus musculus; black-tailed jackrabbit, Lepus californicus; mallard, Anas platyrhynchos; ring-necked pheasant, Phasianus colchicus; American coot, Fulica americana; and red-winged blackbird, Agelaius phoeniceus. Both mice and pheasants from methyl parathion-treated fields had overall mean ChE activities that were significantly (P < 0.05) inhibited compared with controls, and 7, 40, 54 and 57% of individual blackbirds, pheasant, mice, and coots, respectively, had inhibited brain ChE activities (i.e., less than -2 SD of control mean). Although no overall species effect was detected for ethyl parathoid treatment, pheasants (43%), coots (33%), and mice (37%) had significantly inhibited brain ChE activities. Neither of the parathion treatment appeared acutely hazardous to wildlife in or adjacent to rice fields, but sufficient information on potential hazards was obtained to warrant caution in use of these chemicals, especially methyl parathion, in rice fields.

Custer, T.W.; Hill, E.F.; Ohlendorf, H.M.

1985-01-01

358

Rheological behaviors of cellulose in 1-ethyl-3-methylimidazolium chloride/dimethylsulfoxide.  

PubMed

Dynamic rheological behaviors of ?-cellulose 1-ethyl-3-methylimidazolium chloride ([Emim]Cl)/dimethylsulfoxide (DMSO) solutions were investigated in a large range of cellulose concentrations (0.1-10 wt%) at 25°C. The overlap concentration c* and the entanglement concentration ce for cellulose in [Emim]Cl/DMSO were determined to be 0.5 wt% and 2.0 wt% respectively, and the exponents of the specific viscosity ?sp versus cellulose concentration c were determined as 1.1, 2.1 and 4.7 for dilute, semidilute unentangled and entangled regimes respectively, which were in accordance with the scaling prediction for neutral polymer in ? solvent. Under the same cellulose concentration, the complex viscosity ?*, the reptation time ?rep and the relaxation time of a segment between entanglements ?e all decreased with increasing DMSO content in the solvent, while the number of entanglements of cellulose chains and the molar mass of an entanglement strand Me both remained unchanged. PMID:24906758

Wang, Lejun; Gao, Lei; Cheng, Bowen; Ji, Xiujie; Song, Jun; Lu, Fei

2014-09-22

359

Natural prenylated resveratrol analogs arachidin-1 and -3 demonstrate improved glucuronidation profiles and have affinity for cannabinoid receptors  

PubMed Central

1. Rationale The therapeutic promise of trans-resveratrol (tRes) is limited by poor bioavailability following rapid metabolism. We hypothesise that trans-arachidin-1 (tA1) and trans-arachidin-3 (tA3), peanut hairy root-derived isoprenylated analogs of tRes, will exhibit slower metabolism/enhanced bioavailability and retain biological activity via cannabinoid receptor (CBR) binding relative to their non-prenylated parent compounds trans-piceatannol (tPice) and tRes, respectively. 2. Results The activities of eight human UDP-glucuronosyltransferases (UGTs) toward these compounds were evaluated. The greatest activity was observed for extrahepatic UGTs 1A10 and 1A7, followed by hepatic UGTs 1A1 and 1A9. Importantly, an additional isoprenyl and/or hydroxyl group in tA1 and tA3 slowed overall glucuronidation. CBR binding studies demonstrated that all analogs bound to CB1Rs with similar affinities (5–18 µM); however, only tA1 and tA3 bound appreciably to CB2Rs. Molecular modelling studies confirmed that the isoprenyl moiety of tA1 and tA3 improved binding affinity to CB2Rs. Finally, although tA3 acted as a competitive CB1R antagonist, tA1 antagonised CB1R agonists by both competitive and non-competitive mechanisms. 3. Conclusions Prenylated stilbenoids may be preferable alternatives to tRes due to increased bioavailability via slowed metabolism. Similar structural analogs might be developed as novel CB therapeutics for obesity and/or drug dependency. PMID:21970716

Brents, Lisa K.; Medina-Bolivar, Fabricio; Seely, Kathryn A.; Nair, Vipin; Bratton, Stacie M.; Ñopo-Olazabal, Luis; Patel, Ronak Y.; Liu, Haining; Doerksen, Robert J.; Prather, Paul L.; Radominska-Pandya, Anna

2013-01-01

360

Glucuronidation and sulfonation, in vitro, of the major endocrine-active metabolites of methoxychlor in the channel catfish, Ictalurus punctatus, and induction following treatment with 3-methylcholanthrene.  

PubMed

The organochlorine pesticide, methoxychlor (MXC), is metabolized in animals to phenolic mono- and bis-demethylated metabolites (OH-MXC and HPTE, respectively) that interact with estrogen receptors and may be endocrine disruptors. The phase II detoxication of these compounds will influence the duration of action of the estrogenic metabolites, but has not been investigated extensively. In this study, the glucuronidation and sulfonation of OH-MXC and HPTE were investigated in subcellular fractions of liver and intestine from untreated, MXC-treated and 3-methylcholanthrene (3-MC)-treated channel catfish, Ictalurus punctatus. MXC-treated fish were given i.p. injections of 2mg MXC/kg daily for 6 days and sacrificed 24h after the last dose. The 3-MC treatment was a single 10mg/kg i.p. dose 5 days prior to sacrifice. In hepatic microsomes from control fish, the V(max) value (mean+/-S.D., n=4) for glucuronidation of OH-MXC was 270+/-50pmol/min/mg protein, higher than found for HPTE (110+/-20pmol/min/mg protein). For each substrate, the V(max) values observed in intestinal microsomes were approximately twice those found in the liver. The K(m) values for OH-MXC and HPTE glucuronidation in control liver were not significantly different and were 0.32+/-0.04mM for OH-MXC and 0.26+/-0.06mM for HPTE. The K(m) for the co-substrate, UDPGA, was higher in liver (0.28+/-0.09mM) than intestine (0.04+/-0.02mM). Treatment with 3-MC but not MXC increased the V(max) for glucuronidation in liver and intestine. Glucuronidation was a more efficient pathway than sulfonation for both substrates, in both tissues. The V(max) values for sulfonation of OH-MXC and HPTE, respectively, in liver cytosol were 7+/-3 and 17+/-4pmol/min/mg protein and in intestinal cytosol were 13+/-3 and 30+/-5pmol/min/mg protein. Treatment with 3-MC but not MXC increased rates of sulfonation of OH-MXC and HPTE and the model substrate, 3-hydroxy-benzo(a)pyrene in both intestine and liver. Comparison of the kinetics of the conjugation pathways with those published for the demethylation of MXC showed that formation of the endocrine-active metabolites was more efficient than either conjugation pathway. Residues of OH-MXC and HPTE were detected in extracts of liver microsomes from MXC-treated fish. This work showed that although OH-MXC and HPTE could be eliminated by glucuronidation and sulfonation, the phase II pathways were less efficient than the phase I pathway leading to formation of these endocrine-active metabolites. PMID:18078677

James, Margaret O; Stuchal, Leah D; Nyagode, Beatrice A

2008-01-31

361

Acetone, methyl ethyl ketone, ethyl acetate, acetonitrile and other polar aprotic solvents are strong inducers of aneuploidy in Saccharomyces cerevisiae.  

PubMed

A diploid yeast strain D61.M was used to study induction of mitotic chromosomal malsegregation, mitotic recombination and point mutation. Several ketones (including acetone and methyl ethyl ketone) and some organic acid esters (including the methyl, ethyl and 2-methoxyethyl esters of acetic acid) and acetonitrile strongly induced aneuploidy but not recombination or point mutation. Only diethyl ketone induced low levels of recombination and point mutation in addition to aneuploidy. Related compounds were weak inducers of aneuploidy: methyl n-propyl ketone, the methyl esters of propionic and butyric acid, acetic acid esters of n- and iso-propanol and ethyl propionate. No mutagenicity was found with n-butyl and isoamyl acetate, ethyl formate, acetyl acetone (2,5-dipentanone) and dioxane. Methyl isopropyl ketone induced only some recombination and point mutation but no aneuploidy. Efficient induction was only observed with a treatment protocol in which growing cells were exposed to the chemicals during a growth period of 4 h at 28 degrees C followed by incubation in ice for more than 90 min, usually overnight for 16-17 h. Aneuploid cells could be detected in such cultures during a subsequent incubation at growth temperature if the chemical was still present. Detailed analysis showed that there was a high incidence of multiple events of chromosomal malsegregation. It is proposed that the mutagenic agents act directly on tubulin during growth so that labile microtubules are formed which dissociate in the cold. When cells are brought back to temperatures above the level critical for reassembly of tubulin and allowed to grow, faulty microtubules are formed. PMID:3887145

Zimmermann, F K; Mayer, V W; Scheel, I; Resnick, M A

1985-05-01

362

Preparation of diastereomeric ?-d-glucuronides of the bronchodilator procaterol using immobilized rabbit liver microsomal enzymes  

Microsoft Academic Search

Summary  Liver microsomal pellets from a phénobarbital induced New Zealand white male rabbit were prepared, solubilized, and reacted\\u000a with cyanogen bromide activated Sepharose beads to form an immobilized microsomal enzyme preparation. Viability of bound enzymes\\u000a was determined using established methods. Racemic erythro-[3H]-procaterol hydrochloride was incubated with immobilized microsomal enzymes at room temperature in 0.1 M potassium phosphate\\u000a buffer (pH 7.4) together

T. F. Woolf; T. Chang

1989-01-01

363

Supercritical extraction and desulphurization of Beypazari lignite by ethyl alcohol/NaOH treatment; Effect of ethyl alcohol/coal ratio and NaOH  

SciTech Connect

The authors report an investigation of the solubilization and desulphurization of Beypazari lignite with supercritical ethyl alcohol/NaOH. Supercritical experiments of 60 minutes were done in microreactors of 15 ml at 245{sup 0}C by changing the ethyl alcohol/coal ratio from 3 to 20 under a nitrogen atmosphere. As the ethyl alcohol/coal ratio was increased the yield of solubilization and desulphurization also increased. Higher yields of extraction in the case of ethyl alcohol/NaOH experiments may be due to the fact that alcohols can transfer hydrogen more easily in the presence of bases. The average molecular weights of liquid products obtained in experiments with ethyl alcohol/coal ratios of 3, 6 and 20 were 430, 450 and 465, respectively. In experiments with ethyl alcohol/NaOH system as the ethyl alcohol/coal ratio was increased from 3 to 20 the sulphur content of the coal decreased to 0.75%. In experiments with greater ethyl alcohol/coal ratios mercaptane type sulphur chemicals have been extracted, disulphides were missing in these extracts.

Yurum, Y.; Tugluhan, A. (Hacettepe Univ., Dept. of Chemistry, Beytepe, Ankara (TK))

1990-02-01

364

Renal glucuronidation and multidrug resistance protein 2-/ multidrug resistance protein 4-mediated efflux of mycophenolic acid: interaction with cyclosporine and tacrolimus.  

PubMed

Mycophenolic acid (MPA) is an immunosuppressant used in transplant rejection, often in combination with cyclosporine (CsA) and tacrolimus (Tac). The drug is cleared predominantly via the kidneys, and 95% of the administered dose appears in urine as 7-hydroxy mycophenolic acid glucuronide (MPAG). The current study was designed to unravel the renal excretory pathway of MPA and MPAG, and their potential drug-drug interactions. The role of multidrug resistance protein (MRP) 2 and MRP4 in MPA disposition was studied using human embryonic kidney 293 (HEK293) cells overexpressing the human transporters, and in isolated, perfused kidneys of Mrp2-deficient rats and Mrp4-deficient mice. Using these models, we identified MPA as substrate of MRP2 and MRP4, whereas its MPAG appeared to be a substrate of MRP2 only. CsA inhibited MPAG transport via MRP2 for 50% at 8 ?M (P < 0.05), whereas Tac had no effect. This was confirmed by cell survival assays, showing a 10-fold increase in MPA cytotoxicity (50% reduction in cell survival changed from 12.2 ± 0.3 ?M to 1.33 ± 0.01 ?M by MPA + CsA; P < 0.001) and in perfused kidneys, showing a 50% reduction in MPAG excretion (P < 0.05). The latter effect was observed in Mrp2-deficient animals as well, supporting the importance of Mrp2 in MPAG excretion. CsA, but not Tac, inhibited MPA glucuronidation by rat kidney homogenate and human uridine 5'-diphospho-glucuronosyltransferase-glucuronosyltransferase 1A9 (P < 0.05 and P < 0.01, respectively). We conclude that MPA is a substrate of both MRP2 and MRP4, but MRP2 is the main transporter involved in renal MPAG excretion. In conclusion, CsA, but not Tac, influences MPA clearance by inhibiting renal MPA glucuronidation and MRP2-mediated MPAG secretion. PMID:24486136

El-Sheikh, Azza A K; Koenderink, Jan B; Wouterse, Alfons C; van den Broek, Petra H H; Verweij, Vivienne G M; Masereeuw, Rosalinde; Russel, Frans G M

2014-07-01

365

Investigation of morphine and morphine glucuronide levels and cytochrome P450 isoenzyme 2D6 genotype in codeine-related deaths.  

PubMed

Compared to morphine and morphine-6-glucuronide (M6G), codeine and its other major metabolites codeine-6-glucuronide and norcodeine have weak affinity to opioid ?-receptors. Analgesic effects of codeine are thus largely dependent on metabolic conversion to morphine by the polymorphic cytochrome P450 isoenzyme 2D6 (CYP2D6). How this relates to toxicity and post-mortem whole blood levels is not known. This paper presents a case series of codeine-related deaths where concentrations of morphine, M6G and morphine-3-glucuronide (M3G), as well as CYP2D6 genotype, are taken into account. Post-mortem toxicological specimens from a total of 1444 consecutive forensic autopsy cases in Central Norway were analyzed. Among these, 111 cases with detectable amounts of codeine in femoral blood were identified, of which 34 had femoral blood concentrations exceeding the TIAFT toxicity threshold of 0.3mg/L. Autopsy records of these 34 cases were retrieved and reviewed. In the 34 reviewed cases, there was a large variability in individual morphine to codeine concentration ratios (M/C ratios), and morphine levels could not be predicted from codeine concentrations, even when CYP2D6 genotype was known. 13 cases had codeine concentrations exceeding the TIAFT threshold for possibly lethal serum concentrations (1.6 mg/L). Among these, 8 individuals had morphine concentrations below the toxic threshold according to TIAFT (0.15 mg/L). In one case, morphine as well as M6G and M3G concentrations were below the limit of detection. A comprehensive investigation of codeine-related fatalities should, in addition to a detailed case history, include quantification of morphine and morphine metabolites. CYP2D6 genotyping may be of interest in cases with unexpectedly high or low M/C ratios. PMID:22285504

Frost, Joachim; Helland, Arne; Nordrum, Ivar S; Slørdal, Lars

2012-07-10

366

Distribution and organoleptic impact of ethyl 2-methylbutanoate enantiomers in wine.  

PubMed

The enantiomers of ethyl 2-methylbutanoate were assayed in several wines using chiral gas chromatography (?-cyclodextrin). Analyses of 37 commercial red wines from various vintages and origins revealed the almost exclusive presence of the S-enantiomeric form. The average concentration was ?50 ?g/L, but the oldest samples were found to contain higher ethyl 2-methylbutanoate levels than the youngest wines. The olfactory threshold of a racemic mixture of ethyl (2R)-2-methylbutanoate and ethyl (2S)-2-methylbutanoate (50:50, m/m) in dilute alcohol solution was 2.60 ?g/L, almost twice that of the S-form, which was 1.53 ?g/L. Ethyl (2S)-2-methylbutanoate and the racemic mixture of ethyl (2R)-2-methylbutanoate and ethyl (2S)-2-methylbutanoate had different aromatic nuances: the former was mainly defined by fruity descriptors, such as green apple (Granny Smith) and strawberry, whereas the latter had an unspecific, caustic, fruity, solvent odor. Sensory analysis revealed an enhancing effect of ethyl (2S)-2-methylbutanoate on the perception of fruity aromas in the matrices studied: the "olfactory threshold" of the fruity pool, consisting of esters found in red wines, in dilute alcohol solution alone was higher than that of the same mixture supplemented with 50 ?g/L ethyl (2S)-2-methylbutanoate. The sensory profiles of these aromatic reconstitutions highlighted the contribution of ethyl (2S)-2-methylbutanoate to black-berry-fruit descriptors. PMID:24844693

Lytra, Georgia; Tempere, Sophie; de Revel, Gilles; Barbe, Jean-Christophe

2014-06-01

367

Identification of diet-derived constituents as potent inhibitors of intestinal glucuronidation.  

PubMed

Drug-metabolizing enzymes within enterocytes constitute a key barrier to xenobiotic entry into the systemic circulation. Furanocoumarins in grapefruit juice are cornerstone examples of diet-derived xenobiotics that perpetrate interactions with drugs via mechanism-based inhibition of intestinal CYP3A4. Relative to intestinal CYP3A4-mediated inhibition, alternate mechanisms underlying dietary substance-drug interactions remain understudied. A working systematic framework was applied to a panel of structurally diverse diet-derived constituents/extracts (n = 15) as inhibitors of intestinal UDP-glucuronosyl transferases (UGTs) to identify and characterize additional perpetrators of dietary substance-drug interactions. Using a screening assay involving the nonspecific UGT probe substrate 4-methylumbelliferone, human intestinal microsomes, and human embryonic kidney cell lysates overexpressing gut-relevant UGT1A isoforms, 14 diet-derived constituents/extracts inhibited UGT activity by >50% in at least one enzyme source, prompting IC(50) determination. The IC(50) values of 13 constituents/extracts (?10 ?M with at least one enzyme source) were well below intestinal tissue concentrations or concentrations in relevant juices, suggesting that these diet-derived substances can inhibit intestinal UGTs at clinically achievable concentrations. Evaluation of the effect of inhibitor depletion on IC(50) determination demonstrated substantial impact (up to 2.8-fold shift) using silybin A and silybin B, two key flavonolignans from milk thistle (Silybum marianum) as exemplar inhibitors, highlighting an important consideration for interpretation of UGT inhibition in vitro. Results from this work will help refine a working systematic framework to identify dietary substance-drug interactions that warrant advanced modeling and simulation to inform clinical assessment. PMID:25008344

Gufford, Brandon T; Chen, Gang; Lazarus, Philip; Graf, Tyler N; Oberlies, Nicholas H; Paine, Mary F

2014-10-01

368

UDP-Glucuronosyltransferase 1A Determinates Intracellular Accumulation and Anti-Cancer Effect of ?-Lapachone in Human Colon Cancer Cells  

PubMed Central

?-lapachone (?-lap), an NAD(P)H:quinone oxidoreductase 1 (NQO1) targeting antitumor drug candidate in phase II clinical trials, is metabolically eliminated via NQO1 mediated quinone reduction and subsequent UDP-glucuronosyltransferases (UGTs) catalyzed glucuronidation. This study intends to explore the inner link between the cellular glucuronidation and pharmacokinetics of ?-lap and its apoptotic effect in human colon cancer cells. HT29 cells S9 fractions exhibited high glucuronidation activity towards ?-lap, which can be inhibited by UGT1A9 competitive inhibitor propofol. UGT1A siRNA treated HT29 cells S9 fractions displayed an apparent low glucuronidation activity. Intracellular accumulation of ?-lap in HCT116 cells was much higher than that in HT29 cells, correlated with the absence of UGT1A in HCT116 cells. The cytotoxic and apoptotic effect of ?-lap in HT29 cells were much lower than that in HCT116 cells; moreover, ?-lap triggered activation of SIRT1-FOXO1 apoptotic pathway was observed in HCT116 cells but not in HT29 cells. Pretreatment of HT29 cells with UGT1A siRNA or propofol significantly decreased ?-lap’s cytotoxic and apoptotic effects, due to the repression of glucuronidation and the resultant intracellular accumulation. In conclusion, UGT1A is an important determinant, via switching NQO1-triggered redox cycle to metabolic elimination, in the intracellular accumulation of ?-lap and thereafter its cytotoxicity in human colon cancer cells. Together with our previous works, we propose that UGTs determined cellular pharmacokinetics is an important determinant in the apoptotic effects of NQO1 targeting substrates serving as chemotherapeutic drugs. PMID:25692465

Liu, Huiying; Li, Qingran; Cheng, Xuefang; Wang, Hong; Wang, Guangji; Hao, Haiping

2015-01-01

369

Assessment of acute oral and dermal toxicity of 2 ethyl-carbamates with activity against Rhipicephalus microplus in rats.  

PubMed

The acute oral and dermal toxicity of two new ethyl-carbamates (ethyl-4-bromophenyl-carbamate and ethyl-4-chlorophenyl-carbamate) with ixodicide activity was determined in rats. The oral LD50 of each carbamate was 300 to 2000 mg/kg, and the dermal LD50 of each carbamate was >5000 mg/kg. Clinically, the surviving rats that had received oral doses of each carbamate showed decreased weight gain (P < 0.05) and had slight nervous system manifestations. These clinical signs were evident from the 300 mg/kg dose and were reversible, whereas the 2000 mg/kg dose caused severe damage and either caused their death or was motive for euthanasia. At necropsy, these rats had dilated stomachs and cecums with diffuse congestion, as well as moderate congestion of the liver. Histologically, the liver showed slight degenerative lesions, binucleated hepatocytes, focal coagulative necrosis, and congestion areas; the severity of the lesions increased with dosage. Furthermore, an slight increase in gamma-glutamyltransferase, lactate dehydrogenase, and creatinine was observed in the plasma. The dermal application of the maximum dose (5000 mg/kg) of each carbamate did not cause clinical manifestations or liver and skin alterations. This finding demonstrates that the carbamates under study have a low oral hazard and low acute dermal toxicity. PMID:24883331

Prado-Ochoa, María Guadalupe; Gutiérrez-Amezquita, Ricardo Alfonso; Abrego-Reyes, Víctor Hugo; Velázquez-Sánchez, Ana María; Muñoz-Guzmán, Marco Antonio; Ramírez-Noguera, Patricia; Angeles, Enrique; Alba-Hurtado, Fernando

2014-01-01

370

Assessment of Acute Oral and Dermal Toxicity of 2 Ethyl-Carbamates with Activity against Rhipicephalus microplus in Rats  

PubMed Central

The acute oral and dermal toxicity of two new ethyl-carbamates (ethyl-4-bromophenyl-carbamate and ethyl-4-chlorophenyl-carbamate) with ixodicide activity was determined in rats. The oral LD50 of each carbamate was 300 to 2000?mg/kg, and the dermal LD50 of each carbamate was >5000?mg/kg. Clinically, the surviving rats that had received oral doses of each carbamate showed decreased weight gain (P < 0.05) and had slight nervous system manifestations. These clinical signs were evident from the 300?mg/kg dose and were reversible, whereas the 2000?mg/kg dose caused severe damage and either caused their death or was motive for euthanasia. At necropsy, these rats had dilated stomachs and cecums with diffuse congestion, as well as moderate congestion of the liver. Histologically, the liver showed slight degenerative lesions, binucleated hepatocytes, focal coagulative necrosis, and congestion areas; the severity of the lesions increased with dosage. Furthermore, an slight increase in gamma-glutamyltransferase, lactate dehydrogenase, and creatinine was observed in the plasma. The dermal application of the maximum dose (5000?mg/kg) of each carbamate did not cause clinical manifestations or liver and skin alterations. This finding demonstrates that the carbamates under study have a low oral hazard and low acute dermal toxicity. PMID:24883331

Prado-Ochoa, María Guadalupe; Gutiérrez-Amezquita, Ricardo Alfonso; Abrego-Reyes, Víctor Hugo; Velázquez-Sánchez, Ana María; Muñoz-Guzmán, Marco Antonio; Ramírez-Noguera, Patricia; Angeles, Enrique; Alba-Hurtado, Fernando

2014-01-01

371

Cholestane as a digestibility marker in the absorption of polyunsaturated fatty acid ethyl esters in Atlantic salmon.  

PubMed

Salmonid fish require long-chain n-3 fatty acids in their diet. The digestibility of different chemical forms of fish oil fatty acids, fed as triacylglycerols, free fatty acids or ethyl esters, was examined in 300 g farmed Atlantic salmon (Salmo salar) using cholestane as an indicator of fat absorption in lieu of the chromium oxide (Cr2O3) which is commonly used as a marker in digestibility studies. It was established that the two digestibility markers gave similar results. Conveniently, cholestane does not require a separate analysis if fatty acids are to be determined by appropriate gas-liquid chromatography. The long-chain polyunsaturated fatty acids were particularly well absorbed, the apparent digestibility being 90-98% when feeding triacylglycerols or free fatty acids. However, the digestibility of monounsaturated fatty acids (75-94%) was lower, and lower still for saturated fatty acids (50-80%). Ethyl esters of fatty acids were significantly less well absorbed (P less than 0.05) than were the corresponding fatty acids in free acid or triacylglycerol form. Irrespective of dietary fat type, only free fatty acids were identified in feces, indicating total hydrolysis of triacylglycerols and ethyl esters. PMID:1630276

Sigurgisladottir, S; Lall, S P; Parrish, C C; Ackman, R G

1992-06-01

372

Liquid chromatography-tandem mass spectrometry assay for the quantitation of plagiochin E and its main metabolite plagiochin E glucuronides in rat plasma.  

PubMed

Plagiochin E, a macrocyclic bisbibenzyl isolated from liverwort Marchantia polymorpha, was found to have antifungal activity. To evaluate the pharmacokinetics of plagiochin E in rats, a sensitive and specific liquid chromatography/tandem mass spectrometric (LC-MS/MS) method was developed and validated for the quantitation of plagiochin E and its total conjugated metabolites in rat plasma. For detection, a Sciex API 4000 LC-MS/MS with a TurboIonSpray ionization (ESI) inlet in the negative ion-multiple reaction monitoring (MRM) mode was used. The plasma samples were pretreated by a simple liquid-liquid extraction with ethyl acetate. The concentration of plagiochin E parent form was determined directly and the concentration of plagiochin E conjugated metabolites was assayed in the form of plagiochin E after treatment with beta-glucuronidase/sulfatase. The statistical evaluation for this method reveals excellent linearity, accuracy and precision for the range of concentrations 0.5-1000.0 ng/mL. The method had a lower limit of quantification (LLOQ) of 0.5 ng/mL for plagiochin E in 50 microL of plasma. The method was successfully applied to the characterization of the pharmacokinetic profile of plagiochin E in rats after an oral and an intravenous administration. PMID:18420369

Xing, Jie; Lv, Beibei; Xie, Chunfeng; Qu, Jianbo; Lou, Hongxiang

2008-08-01

373

Phytoene desaturase inhibition by O-(2-phenoxy)ethyl-N-aralkylcarbamates.  

PubMed

O-[1-Ethyl-2-(3-trifluoromethylphenoxy)]ethyl-N-benzylcarbamate exhibits a marked inhibition of carotenoid biosynthesis. Forty-one analogues were synthesized and assayed for plant-type phytoene desaturase (PDS) and zeta-carotene desaturase (ZDS) inhibition in a cell-free system using recombinant enzymes obtained from Escherichia coli transformants. The target enzyme of all carbamates synthesized in this study is PDS and not ZDS; no inhibition of ZDS was observed using a 10(-4) M inhibitor concentration. Four compounds, O-[1-ethyl-2-(3-trifluoromethylphenoxy)]ethyl-N-(2-phenylethyl)carbamate (23), O-[1-ethyl-2-(3-trifluoromethylphenoxy)]ethyl-N-(2-chlorobenzyl)carbamate (25), O-[1-ethyl-2-(3-trifluoromethylphenoxy)]ethyl-N-(2-chlorobenzyl)carbamate (26), and O-[1-methyl-2-(3-trifluoromethylphenoxy)]ethyl-N-benzylcarbamate (30), were the most potent PDS inhibitors. Their pI(50) values, the negative logarithms of the molar concentration that produces a 50% inhibition, were 7.5, representing the same inhibitory activity as norflurazon. With respect to a structure-activity relationship the oxygen atom of the phenoxy group and a carbamate structure in O-(1-ethyl-2-phenoxy)ethyl-N-aralkylcarbamates studied were found to be essential for strong PDS inhibitors. Also, introduction of an ethyl group at the alpha-position of the ethylene bridge between the phenoxy group and the carbamate was important for a strong PDS inhibitor. Substituents at the 2- and/or 3-position of the phenoxybenzene ring were found to be favorable to a strong PDS inhibition of the analogues. PMID:12720390

Ohki, Shinpei; Miller-Sulger, Roswitha; Wakabayashi, Ko; Pfleiderer, Wolfgang; Böger, Peter

2003-05-01

374

Fractionation of menhaden oil ethyl esters using supercritical fluid CO 2  

Microsoft Academic Search

Supercritical fluid CO2 was used to fractionate menhaden oil fatty acid ethyl esters to obtain concentrates of the esters of allcis-5,8,11,14,17-eicosapentaenoic acid (EPA) and allcis-4,7,10,13,16,19-docosahexaenoic acid (DHA). Separation of the ethyl esters was found to occur primarily by carbon number,\\u000a thus limiting the degree to which the ethyl esters of EPA and DHA could be concentrated. Urea fractionation of whole

W. B. Nilsson; E. J. Gauglitz; J. K. Hudson; V. F. Stout; J. Spinelli

1988-01-01

375

The effect of sugars on the retention of ethyl butyrate by gellan gels.  

PubMed

The effect of sucrose, glucose and fructose on the retention of ethyl butyrate by low acyl gellan gels was investigated by static headspace gas chromatography. The air/biopolymer partition coefficient (K) and percentage of retention (R%) were determined. When 5 g of sample were left to equilibrate at 37 °C for 24 h, the obtained results were explained in terms of gel rigidity, as increased rigidity resulted in increased aroma retention. Glucose showed the greatest aroma release among the sugars and resulted in either the same or increased aroma release with increasing concentration. Increasing concentrations of fructose and sucrose did not alter aroma release significantly. For 15 g of sample mass, sucrose exhibited the lowest partition coefficient values among the sugars. The two higher sucrose concentrations resulted in decreased coefficient values. For fructose and glucose, aroma retention decreased with increasing concentration. The percentage of retention values were positive for all sugars, throughout their concentration range and for both experiments. PMID:24679778

Evageliou, Vasiliki; Patsiakou, Anna

2014-08-15

376

Energy transfer of ethyl iodine studied by time-resolved photoelectron imaging  

NASA Astrophysics Data System (ADS)

Ultrafast dynamics of electronically excited states in ethyl iodine is studied using femtosecond time-resolved photoelectron imaging coupled with mass spectroscopy. The dissociation constant of the A band was measured to be about 57 fs. Upon two 400 nm photon excitation to the B band, the time evolution of the parent ion with consists of two components. The fast component with a time constant of 50 fs revealed the energy transfer from the higher Rydberg states to the B band. The slow one was determined to be 1.42 ps, which was due to predissociation relaxation from the B band to the repulsive A band.

Xu, Yanqi; Qiu, Xuejun; Abulimiti, Bumaliya; Wang, Yanmei; Tang, Ying; Zhang, Bing

2012-12-01

377

Bisphenol-A (BPA), BPA glucuronide, and BPA sulfate in mid-gestation umbilical cord serum in a Northern and Central California population  

PubMed Central

Bisphenol-A (BPA) is an endocrine disrupting chemical used in numerous consumer products, resulting in universal exposure in the United States. Prenatal exposure to BPA is associated with numerous reproductive and developmental effects in animals. However, little is known about human fetal exposure or metabolism of BPA during mid-gestation. In the present study, we present a new liquid chromatography-tandem mass spectrometry method to directly measure concentrations of BPA and two predominant metabolic conjugates – BPA glucuronide and BPA sulfate – in umbilical cord serum collected from elective 2nd trimester pregnancy terminations. We detected at least one form of BPA in all umbilical cord serum samples: BPA (GM 0.16; range glucuronide (GM 0.14; range

Gerona, Roy R.; Woodruff, Tracey J.; Dickenson, Carrie A.; Pan, Janet; Schwartz, Jackie M.; Sen, Saunak; Friesen, Matthew M.; Fujimoto, Victor Y.; Hunt, Patricia A.

2013-01-01

378

Hepatic disposition and biliary excretion of bilirubin and bilirubin glucuronides in intact rats. Differential processing of pigments derived from intra- and extrahepatic sources.  

PubMed Central

Mechanisms for transport of bilirubin and its conjugates in hepatocytes have not been defined. We investigated the hepatic processing of bilirubin glucuronides and their precursors, and characterized the disposition of bile pigments arising from intraversus extrahepatic sources. Tracer doses of purified radiolabeled biliverdin, bilirubin, bilirubin monoglucuronide (BMG) or diglucuronide (BDG) were administered intravenously to intact normal or jaundiced homozygous Gunn rats. Rapid sequential analysis of radiolabeled BMG and BDG in bile revealed comparable excretion patterns following biliverdin and bilirubin injection, with BDG as the major pigment. Biliary excretion of radiolabeled conjugates from injected BMG was more rapid, with BMG predominating. Excretion of injected BDG in normal rats and BMG or BDG in Gunn rats was virtually identical to that of unaltered BMG in normal rats. Model independent analysis by deconvolution provided objective comparison of the disposition of radiolabeled pigments from the different sources. These findings indicate that bilirubin glucuronides formed in the liver from endogenous (hepatic) and exogenous (extrahepatic) sources of bilirubin follow a similar excretory pathway. BMG formed endogenously is converted preferentially to BDG, whereas circulating BMG is excreted predominantly unchanged. Exogenous conjugated bilirubins are excreted more rapidly than those generated intrahepatically, by a transcellular pathway that is largely independent of the conjugation system. PMID:3558820

Crawford, J M; Ransil, B J; Potter, C S; Westmoreland, S V; Gollan, J L

1987-01-01

379

Impact of trans-resveratrol-sulfates and -glucuronides on endothelial nitric oxide synthase activity, nitric oxide release and intracellular reactive oxygen species.  

PubMed

Resveratrol (3,5,4'-trihydroxy-trans-stilbene) is a polyphenolic natural product mainly present in grape skin, berries and peanuts. In the vasculature resveratrol is thought to boost endothelial function by increasing endothelial nitric oxide synthase (eNOS) expression, by enhancing eNOS activity, and by reduction of reactive oxygen species (ROS) levels. Recent studies show that dietary resveratrol is metabolized in the liver and intestine into resveratrol-sulfate and -glucuronide derivatives questioning the relevance of multiple reported mechanistic in vitro data on resveratrol. In this study, we compare side by side different physiologically relevant resveratrol metabolites (resveratrol sulfates- and -glucuronides) and their parent compound in their influence on eNOS enzyme activity, endothelial NO release, and intracellular ROS levels. In contrast to resveratrol, none of the tested resveratrol metabolites elevated eNOS enzyme activity and endothelial NO release or affected intracellular ROS levels, leaving the possibility that not tested metabolites are active and able to explain in vivo findings. PMID:25329867

Ladurner, Angela; Schachner, Daniel; Schueller, Katharina; Pignitter, Marc; Heiss, Elke H; Somoza, Veronika; Dirsch, Verena M

2014-01-01

380

First chemical synthesis and in vitro characterization of the potential human metabolites 5-o-feruloylquinic acid 4'-sulfate and 4'-O-glucuronide.  

PubMed

Feruloylquinic acids are a major class of biologically active phenolic antioxidants in coffee beans, but their metabolic fate is poorly understood. The present study investigated the phase II metabolism of feruloylquinic acids with selected human sulfotransferases (SULT1A1 and SULT1E1) and uridine 5'-diphosphoglucuronosyltransferases (UGT1A1 and UGT1A9). For unequivocal metabolite identification, the chemical synthesis of two potential human metabolites of 5-O-feruloylquinic acid, the 4'-sulfated and 4'-O-glucuronidated conjugates, has been performed for the first time. Following incubation with human SULT1A1 or SULT1E1, formation of 5-O-feruloylquinic acid 4'-O-sulfate was confirmed by matching its HPLC and MS data with those of the authentic standard. On the other hand, no glucuronide conjugates were detected after incubation with human uridine 5'-diphosphoglucuronosyltransferases. These results suggest that sulfation can take place on the ferulic acid moiety of feruloylquinic acids and may be a major metabolic pathway for feruloylquinic acids in humans. PMID:21417257

Menozzi-Smarrito, Candice; Wong, Chi Chun; Meinl, Walter; Glatt, Hansruedi; Fumeaux, René; Munari, Caroline; Robert, Fabien; Williamson, Gary; Barron, Denis

2011-05-25

381

Ethyl-Substituted Stilbazolium Derivatives for Second-Order Nonlinear Optics  

NASA Astrophysics Data System (ADS)

1-Methyl-4-(2-(4-(dimethylamino)phenyl)ethenyl)pyridinium iodide and its three analogues with ethyl-substituted cations were prepared. The solubility in organic solvents was confirmed to increase by ethyl substitution. Counter anion exchange afforded several SHG active crystals even in ethyl-substituted derivatives, and 1-ethyl-4-(2-(4-(dimethylamino)phenyl)ethenyl)pyridinium p-nitrobenzenesulfonate was estimated to have an off-diagonal d component twice as larger as that of 1-methyl-4-(2-(4-(dimethylamino)phenyl)ethenyl)pyridinium p-toluenesulfonate (DAST).

Okada, Shuji; Nogi, Kyoko; , Anwa; Tsuji, Kyoko; Duan, Xuan-Ming; Oikawa, Hidetoshi; Matsuda, Hiro; Nakanishi, Hachiro

2003-02-01

382

Bioconversion of ethyl (R)-4-cyano-3-hydroxybutyate into (R)-ethyl-3-hydroxyglutarate via an indirect pathway by Rhodococcus boritolerans.  

PubMed

(R)-Ethyl-3-hydroxyglutarate, (R)-3, is an intermediate in the synthesis of the statin side chain. Here, a new two-step, indirect biotransformation pathway involving the formation of ethyl (R)-4-carbamoyl-3-hydroxybutanoate, (R)-2, as an intermediate for (R)-3 production was developed using Rhodococcus boritolerans with ethyl (R)-4-cyano-3-hydroxybutyate, (R)-1, as substrate. Maximum conversion was with 10 g (R)-1/l, 7 g cells/l (dry wt), pH 7.5 and 25°C. A yield of 98 ± 0.5% (w/w) was attained within 8 h. PMID:22261862

Yang, Ming-Jia; Wang, Xiang-Jing; Yang, Zhong-Yi; An, Jing; Xiang, Wen-Sheng; Zhang, Ji

2012-05-01

383

Application of tandem mass spectrometry combined with gas chromatography to the routine analysis of ethyl carbamate in stone-fruit spirits.  

PubMed

Gas chromatography (GC) coupled to mass spectrometry (MS) operated in selected ion monitoring (SIM) mode is currently the method of choice for the determination of the toxic contaminant ethyl carbamate in alcoholic beverages. However, even after extensive sample cleanup over diatomaceous earth columns, the identity of ethyl carbamate often cannot be ascertained with confidence, due to inconsistent ratios of the SIM ions m/z 62, 74 and 44 because the qualifier ions are highly susceptible to interferences. Therefore, a new method combining GC and tandem MS using a triple-quadrupole instrument is introduced to determine ethyl carbamate in stone-fruit spirits. For quantitative analysis the characteristic transitions of m/z 74 --> 44 and m/z 62 --> 44 for ethyl carbamate as well as m/z 64 --> 44 for the deuterated internal standard ethyl carbamate-d5 were monitored in the multiple reaction monitoring (MRM) mode. In the validation studies, ethyl carbamate exhibited good linearity with a regression coefficient of 1.000. The limits of detection and quantitation were 0.01 and 0.04 mg/L. The recovery of the method was 100.4 +/- 9.4%. The precision never exceeded 7.8% (intraday) and 10.1% (interday) and the trueness never exceeded 11.3% (intraday) and 12.2% (interday) at any of the concentrations examined, indicating good assay accuracy. A good agreement of analytical results between a previously developed GC/MS SIM method and the GC/MS/MS MRM procedure was found (R=0.987). Regarding the validation data, the procedure is sensitive, selective and reproducible. The applicability of the developed method was demonstrated by the investigation of 70 stone-fruit spirits from commercial trade. The ethyl carbamate concentration of the samples ranged between 0.07 and 7.70 mg/L (mean 1.21 mg/L). The main advantage of the developed GC/MS/MS method is the reliability of the results without the need for time-consuming confirmatory analyses. PMID:15593063

Lachenmeier, Dirk W; Frank, Willi; Kuballa, Thomas

2005-01-01

384

Regiospecific distribution of fatty acids in triacylglycerols of Artemia franciscana nauplii enriched with fatty acid ethyl esters  

Microsoft Academic Search

This paper reports the positional distribution of fatty acids in triacylglycerols (TAG) of Artemia franciscana nauplii enriched with each of palmitic (16:0), oleic (18:1n-9), linoleic (18:2n-6), linolenic (18:3n-3), eicosapentaenoic (20:5n-3), and docosahexaenoic (22:6n-3) acid ethyl esters. TAG extracted from the enriched and unenriched nauplii were subjected to regiospecific analysis to determine the fatty acid compositions of the sn-1(3) and sn-2

Yasuhiro Ando; Yoshiaki Oomi; Keiichi Narukawa

2002-01-01

385

Tetra­kis(?-4-ethyl­benzoato-?2 O:O?)­bis­[(4-ethyl­benzoic acid-?O)copper(II)  

PubMed Central

The molecule of the title compound, [Cu2(C9H9O2)4(C9H10O2)2], lies on a center of inversion. It consists of four bridging ethyl­benzoate ligands, forming a cage around two Cu atoms in a syn–syn configuration, and two monodentate ethyl­benzoic acid ligands bonded apically to the square-planar Cu atoms. The Cu?Cu distance is 2.6047?(5)?Å. PMID:21202792

Sunil, Abraham C.; Bezuidenhoudt, Barend C. B.; Janse van Rensburg, J. Marthinus

2008-01-01

386

Pharmacokinetics of mycophenolic acid and its glucuronide metabolites in stable adult liver transplant recipients with renal dysfunction on a low-dose calcineurin inhibitor regimen and mycophenolate mofetil.  

PubMed

Low-dose calcineurin inhibitors (CNIs) in combination with a fixed dose (2 g/d) of mycophenolate mofetil (MMF) are a strategy to minimize exposure to cyclosporine (CSA) or tacrolimus (TAC) and thus reduce CNI-related side effects. This study compared the pharmacokinetics (PK) of mycophenolic acid (MPA) and its glucuronide metabolites in stable adult liver transplant recipients with moderately impaired renal function converted from a standard to a low-dose CNI regimen in combination with a fixed dose of MMF. Full 12-hour PK profiles of MPA, free MPA, the aryl glucuronide (MPAG), and the acyl glucuronide (AcMPAG) were obtained from 30 stable liver transplant patients on low-dose CNI (CSA, n = 12; TAC, n = 18) therapy at least 3 months after initiation of low-dose therapy. Predose CSA and TAC concentrations (quantified by liquid chromatography-tandem mass spectrometry) ranged from 17 to 35 and 1.1 to 3.7 microg/L, respectively. The PK variables for MPA, MPAG, AcMPAG, and free MPA displayed wide interindividual variability. Of note was the observation that there were no significant differences in the exposure to MPA, MPAG, and free MPA between the CSA and TAC groups. MPA area under the concentration-time curves (AUCs) ranged from 31.8 to 102.1 (median: 52.9) mg.h(-1).L(-1) in the CSA group and from 22.9 to 144.8 (median: 55.9) mg.h(-1).L(-1) in the TAC group. The AcMPAG AUC on patients under low-dose CSA therapy was higher than that observed under patients on low-dose TAC therapy, although this did not quite reach statistical significance (P = 0.057). Patients receiving CSA had a significantly higher AcMPAG Cmax but not AcMPAG AUC, suggesting that only peak CSA concentrations on a low-dose CSA regimen are sufficient to impair the biliary excretion of AcMPAG. In summary, the influence of CSA on the exposure to MPA was attenuated in stable adult liver transplant recipients on a low-dose CNI therapy in combination with a fixed dose of MMF as compared with patients on a standard CNI therapy. Dose adjustment according to drug concentration measurements is recommended to optimize dosing of MMF and to maintain adequate immunosuppression in patients converted to low-dose CNI therapy. PMID:19307937

Beckebaum, Susanne; Armstrong, Victor W; Cicinnati, Vito Rosario; Streit, Frank; Klein, Christian Georg; Gerken, Guido; Paul, Andreas; Oellerich, Michael

2009-04-01

387

Characterizing the effect of UDP-glucuronosyltransferase (UGT) 2B7 and UGT1A9 genetic polymorphisms on enantioselective glucuronidation of flurbiprofen.  

PubMed

Flurbiprofen (FPF), available commercially as a racemic mixture, is a propionic acid derivative of non-steroidal anti-inflammatory drugs (NSAIDs) with known stereoselective glucuronidation. The major enzyme catalyzing this conjugation reaction is UDP-glucuronosyltransferase (UGT) 2B7, with minor contributions by UGT1A9. This study examines the role of the genetic variants of UGT2B7 and 1A9 enzymes involved in the formation of acyl glucuronides (FPFGs). Variants caused by three single nucleotide polymorphisms (SNPs) (A71S, 211G>T; H268Y, 802C>T; and D398N, 1192G>A) in UGT2B7 and three SNPs (C3Y, 8G>A; M33T, 98T>C; D256N, 766G>A) in UGT1A9 showed activity changes toward different substrates. However the functional impacts of these SNPs on chiral substrates were not examined. Upon stable expression in Bac-to-Bac system, UGT2B7*71S (A(71)S), UGT2B7*2 (H(268)Y) and UGT2B7*5 (D(398)N) were all associated with a decrease in the formation of FPFGs. Compared with UGT2B7*1 (wild-type), UGT2B7*71S exhibited a >2-fold lower intrinsic clearance mainly by altered capacities (V(max)). Furthermore, a >14-fold decreased intrinsic clearance of the *1 protein was produced by UGT2B7*2 and UGT2B7*5. However, no significantly stereoselective difference for the formation of (R)- and (S)-FPFG was found among these UGT2B7 allozymes. UGT1A9*2 (C(3)Y) exhibited a higher V(max) (3.2-fold), K(m) (2.1-fold) and intrinsic clearance (1.6-fold) toward (S)-FPF than UGT1A9*1 (wild-type). UGT1A9*3 (M(33)T) almost lost the catalytic activity to FPF. A significantly stereoselective difference on the glucuronidation of rac-FPF was seen between the two variants compared with the wild type of UGT1A9. PMID:21856293

Wang, Haina; Yuan, Lingmin; Zeng, Su

2011-12-01

388

The effect of benzoic acid or its ethyl ester on rumen fermentation parameters  

E-print Network

The effect of benzoic acid or its ethyl ester on rumen fermentation parameters J Nousiainen Valio be used as mould and yeast inhibitors in silage additives to improve the aerobic stability of silage response of BA or its ethyl ester (EB) on the rumen fermentation parameters in the continuous culture

Paris-Sud XI, Université de

389

Molecular Structure of 3-Ethyl-2-hydroxy-4-methylcyclopent-2-en-1-one  

NSDL National Science Digital Library

3-Ethyl-2-hydroxy-4-methylcyclopent-2-en-1-one is a flavoring agent for maple and caramel odors. It is a fat soluble molecule that is found in tobacco smoke. Compared to other compounds that give food a caramel or maple odor, 3-Ethyl-2-hydroxy-4-methylcyclopent-2-en-1-one has a more burnt quality.

2006-10-04

390

Combustion chemical kinetics of biodiesel and related compounds (methyl and ethyl esters): Experiments and  

E-print Network

1 Combustion chemical kinetics of biodiesel and related compounds (methyl and ethyl esters transportation fuel dedicated to the diesel engine, biodiesel, with an emphasis on ethyl esters because of biodiesel and related components, the main gaps in the field are highlighted to facilitate the convergence

Paris-Sud XI, Université de

391

40 CFR 180.117 - S-Ethyl dipropylthiocarba-mate; tolerances for residues.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false S-Ethyl dipropylthiocarba-mate; tolerances for residues. 180.117 Section 180.117...Specific Tolerances § 180.117 S-Ethyl dipropylthiocarba-mate; tolerances for residues. Tolerances are established...

2010-07-01

392

Characterization of fluoroglycofen ethyl degradation by strain Mycobacterium phocaicum MBWY-1.  

PubMed

A fluoroglycofen ethyl-degrading bacterium, MBWY-1, was isolated from the soil of an herbicide factory. This isolated strain was identified as Mycobacterium phocaicum based on analysis of its 16S rRNA gene sequence and its morphological, physiological, and biochemical properties. The strain was able to utilize fluoroglycofen ethyl as its sole source of carbon for growth and could degrade 100 mg l(-1) of fluoroglycofen ethyl to a non-detectable level within 72 h. The optimum temperature and pH for fluoroglycofen ethyl degradation by strain MBWY-1 were 30°C and 7.0, respectively. Five metabolites produced during the degradation of fluoroglycofen ethyl and were identified by mass spectrometry as {5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitrophenylacyl} hydroxyacetic acid, acifluorfen, 5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-nitrobenzoate, 5-[2-chloro-4-(trifluoromethyl) phenoxy]-2-hydroxyl, and 3-chloro-4-hydroxyl benzotrifluoride. Identification of the metabolites allowed to propose the degradation pathway of fluoroglycofen ethyl by strain MBWY-1. The inoculation of strain MBWY-1 into soil treated with fluoroglycofen ethyl resulted in a higher fluoroglycofen ethyl degradation rate than in uninoculated soil regardless of whether the soil was sterilized or nonsterilized. PMID:21424684

Chen, Liwei; Cai, Tianming; Wang, Qingling

2011-06-01

393

STRUCTURAL CHARACTERIZATION OF ASPHALTENES AND ETHYL ACETATE INSOLUBLE FRACTIONS OF PETROLEUM VACUUM RESIDUES  

Technology Transfer Automated Retrieval System (TEKTRAN)

Asphaltenes and insoluble fractions of vacuum residues (VRs) of two Indian crude oils (viz. Heera and Jodhpur) of different specific gravity were obtained by precipitation of VRs in n-hexane, n-heptane and ethyl acetate, and also by subsequent reprecipitation of n-heptane and ethyl acetate soluble f...

394

Control Study of Ethyl tert-Butyl Ether Reactive Distillation Muhammad A. Al-Arfaj  

E-print Network

Control Study of Ethyl tert-Butyl Ether Reactive Distillation Muhammad A. Al-Arfaj Department structures for ethyl tert-butyl ether (ETBE) reactive distillation columns are studied. Two process The use of reactive distillation has grown in recent years because it results in less expensive and more

Al-Arfaj, Muhammad A.

395

The mid-IR spectra of 9-ethyl guanine, guanosine, and 2-deoxyguanosine  

E-print Network

The mid-IR spectra of 9-ethyl guanine, guanosine, and 2- deoxyguanosine Ali Abo-riziq(a) , Bridgit for Complex Molecular Systems and Biomolecules, 166 10 Prague 6, Czech Republic Abstract We present the mid-IR (400-1800 cm-1 ) spectra of 9-ethyl guanine, guanosine, and 2- deoxyguanosine measured by IR-UV double

de Vries, Mattanjah S.

396

Ethyl carbamate (urethane) in alcoholic beverages and foods: a review.  

PubMed

This IUPAC review covers the earlier studies of the 1970s on the analysis, occurrence and formation of ethyl carbamate (EC) in foods and alcoholic beverages, as well as the more extensive publications that have appeared since the renewed interest in EC in early 1986. In these latter studies, updated analytical procedures, including solid-phase extraction, capillary gas chromatography and mass spectroscopic detection, have become commonplace. These analytical methods are employed for regulatory and data-gathering purposes and provide extensive information on the occurrence of EC, much of which is presented in review. Distinct theories on the sources of EC, mechanisms for its formation and steps required to reduce its levels in stone-fruit brandies, wines and whiskies are summarized. These studies suggest separate pathways of EC formation for each of the three commodities. PMID:2203651

Battaglia, R; Conacher, H B; Page, B D

1990-01-01

397

Fungal degradation of an acetolactate synthase (ALS) inhibitor pyrazosulfuron-ethyl in soil.  

PubMed

Owing to reported phytotoxicity of some sulfonylurea class of herbicides in number of sensitive crops and higher persistence in soil, present study was conducted to isolate and identify pyrazosulfuron-ethyl degrading fungi from soil of rice field. Penicillium chrysogenum and Aspergillus niger, were isolated and identified from rhizospere soil of rice field, as potent pyrazosulfuron-ethyl degrading fungi. Degradation of pyrazosulfuron-ethyl by P. chrysogenum and A. niger, yielded transformation products/metabolites which were identified and characterized by LC/MS/MS. The rate of dissipation of pyrazosulfuron-ethyl was found higher in soil of rice field and soil inoculated with P. chrysogenum. This showed important route of degradation of pyrazosulfuron-ethyl by microbes apart from chemical degradation. PMID:23993642

Sondhia, Shobha; Waseem, Uzma; Varma, R K

2013-11-01

398

New energetic materials: functionalized 1-ethyl-5-aminotetrazoles and 1-ethyl-5-nitriminotetrazoles.  

PubMed

Alkylation of 5-aminotetrazole (1) with 2-chloroethanol leads to a mixture of the N-1 and N-2 isomers of (2-hydroxyethyl)-5-aminotetrazole. Treatment of 1-(2-hydroxyethyl)-5-aminotetrazole (2) with SOCl(2) yielded 1-(2-chlorethyl)-5-aminotetrazole (3). 1-(2-Azidoethyl)-5-aminotetrazole (4) was generated by the reaction of 3 with sodium azide. Nitration of 2, 3, and 4 with HNO(3) (100%) yielded in the case of 2 and 3 1-(2-hydroxyethyl)-5-nitriminotetrazole (5) and 1-(2-chloroethyl)-5-nitriminotetrazole (6). In the case of 4, 1-(2-nitratoethyl)-5-nitriminotetrazole monohydrate (7) was obtained. 1-(2-Azidoethyl)-5-nitriminotetrazole (8) could be obtained by nitration of 4 with NO(2)BF(4) via the formation of potassium 1-(2-azidoethyl)-5-nitriminotetrazolate (9). The reaction of 6 with NaN(3) resulted in the formation of the salt sodium 1-(2-chloroethyl)-5-nitriminotetrazolate (10 a). The deprotonation reaction of 6 was further investigated by the formation of the ammonium salt (10 b). The protonation of 2 and 4 with dilute nitric acid led to 1-(2-hydroxyethyl)-5-aminotetrazolium nitrate (11) and 1-(2-azidoethyl)-5-aminotetrazolium nitrate (12), respectively. Similarly, protonation of 4 with perchloric acid led to 1-(2-azidoethyl)-5-aminotetrazolium perchlorate monohydrate (13). Since 5-nitrimino-tetrazoles can be used as bidentate ligands, the coordination abilities of 5, 6, and 8 were tested by the reaction with copper nitrate trihydrate, yielding the copper complexes trans-[diaquabis{1-(2-hydroxyethyl)-5-nitriminotetrazolato-kappa(2)N(4),O(5)}copper(II)] (14), trans-[diaquabis{1-(2-chloroethyl)-5-nitriminotetrazolato-kappa(2)N(4),O(5)}copper(II)] dihydrate (15), and [diaquabis{1-(2-azidoethyl)-5-nitriminotetrazolato-kappa(2)N(4),O(5)}copper(II)] (16). All compounds were characterized by low-temperature single-crystal X-ray diffraction. In addition, comprehensive characterization (IR, Raman, and multinuclear NMR spectroscopy ((1)H, (13)C), elemental analysis, mass spectrometry, DSC) was performed. The heats of formation of selected compounds were computed by using heats of combustion obtained by bomb calorimetry or calculated by the atomization method. With these values and the densities determined from X-ray crystallography, several detonation parameter were calculated by the EXPLO5 program. Finally, the sensitivities towards impact and friction were determined using a BAM drop hammer and friction tester. PMID:19373791

Stierstorfer, Jörg; Tarantik, Karina R; Klapötke, Thomas M

2009-06-01

399

Crystal structure of azilsartan methyl ester ethyl acetate hemisolvate  

PubMed Central

The title compound, C26H22N4O5 (systematic name: methyl 2-eth­oxy-1-{4-[2-(5-oxo-4,5-di­hydro-1,2,4-oxa­diazol-3-yl)phenyl]benz­yl}-1H-1,3-benzo­diazole-7-carboxyl­ate ethyl acetate hemisolvate), was obtained via cyclization of methyl (Z)-2-eth­oxy-1-{(2?-(N?-hy­droxy­carbamimido­yl)-[1,1?-biphen­yl]-4-yl)meth­yl}-1H-benzo[d]imidazole-7-carboxyl­ate with diphen­yl carbonate. There are two independent mol­ecules (A and B) with different conformations and an ethyl acetate solvent mol­ecule in the asymmetric unit. In mol­ecule A, the dihedral angle between the benzene ring and its attached oxa­diazole ring is 59.36?(17); the dihedral angle between the benzene rings is 43.89?(15) and that between the benzene ring and its attached imidazole ring system is 80.06?(11)°. The corres­ponding dihedral angles in mol­ecule B are 58.45?(18), 50.73?(16) and 85.37?(10)°, respectively. The C—O—C—Cm (m = meth­yl) torsion angles for the eth­oxy side chains attached to the imidazole rings in mol­ecules A and B are 93.9?(3) and ?174.6?(3)°, respectively. In the crystal, the components are linked by N—H?N and C—H?O hydrogen bonds, generating a three-dimensional network. Aromatic ?–? stacking inter­actions [shortest centroid–centroid separation = 3.536?(3)Å] are also observed.

Li, Zhengyi; Liu, Rong; Zhu, Meilan; Chen, Liang; Sun, Xiaoqiang

2015-01-01

400

Biomonitoring of N-ethyl-2-pyrrolidone in automobile varnishers.  

PubMed

N-alkyl-2-pyrrolidones are important organic solvents for varnishes in industry. This study investigates exposure to N-ethyl-2-pyrrolidone (NEP) in varnishing of hard plastic components in an automobile plant. Two specific biomarkers of exposure, 5-hydroxy-N-ethyl-2-pyrrolidone (5-HNEP) and 2-hydroxy-N-ethylsuccinimide (2-HESI), were analyzed in urine samples of 14 workers. For this purpose, pre-shift, post-shift and next day pre-shift urine samples were collected midweek. Twelve workers performed regular work tasks (loading, wiping and packing), whereas two workers performed special work tasks including cleaning the sprayer system with organic solvents containing N-alkyl-2-pyrrolidones. Spot urine samples of nine non-exposed persons of the same plant served as controls. Median post-shift urinary levels of workers with regular work tasks (5-HNEP: 0.15 mg/L; 2-HESI: 0.19 mg/L) were ?5-fold higher compared to the controls (0.03 mg/L each). Continuously increasing metabolite levels, from pre-shift via post-shift to pre-shift samples of the following day, were observed in particular for the two workers with the special working tasks. Maximum levels were 31.01 mg/L (5-HNEP) and 8.45 mg/L (2-HESI). No clear trend was evident for workers with regular working tasks. In summary, we were able to show that workers can be exposed to NEP during varnishing tasks in the automobile industry. PMID:25455446

Koslitz, Stephan; Meier, Swetlana; Schindler, Birgit Karin; Weiss, Tobias; Koch, Holger Martin; Brüning, Thomas; Käfferlein, Heiko Udo

2014-12-01

401

40 CFR 721.10111 - Hexanoic acid, 2-ethyl-, mixed diesters with benzoic acid and diethylene glycol.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Hexanoic acid, 2-ethyl-, mixed diesters with benzoic acid and diethylene glycol. 721.10111 Section...Chemical Substances § 721.10111 Hexanoic acid, 2-ethyl-, mixed diesters with...

2011-07-01

402

40 CFR 721.10110 - Hexanoic acid, 2-ethyl-, mixed diesters with benzoic acid and neopentlyl glycol.  

Code of Federal Regulations, 2011 CFR

...2011-07-01 2011-07-01 false Hexanoic acid, 2-ethyl-, mixed diesters with benzoic acid and neopentlyl glycol. 721.10110 Section...Chemical Substances § 721.10110 Hexanoic acid, 2-ethyl-, mixed diesters with...

2011-07-01

403

40 CFR 721.10111 - Hexanoic acid, 2-ethyl-, mixed diesters with benzoic acid and diethylene glycol.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Hexanoic acid, 2-ethyl-, mixed diesters with benzoic acid and diethylene glycol. 721.10111 Section...Chemical Substances § 721.10111 Hexanoic acid, 2-ethyl-, mixed diesters with...

2010-07-01

404

40 CFR 721.10110 - Hexanoic acid, 2-ethyl-, mixed diesters with benzoic acid and neopentlyl glycol.  

Code of Federal Regulations, 2010 CFR

...2010-07-01 2010-07-01 false Hexanoic acid, 2-ethyl-, mixed diesters with benzoic acid and neopentlyl glycol. 721.10110 Section...Chemical Substances § 721.10110 Hexanoic acid, 2-ethyl-, mixed diesters with...

2010-07-01

405

Slow O-demethylation of methyl triclosan to triclosan, which is rapidly glucuronidated and sulfonated in channel catfish liver and intestine.  

PubMed

The antibacterial personal care product triclosan is discharged in municipal waste, and converted in part by bacteria in sewage sludge and soil to its more lipid-soluble methyl ether, methyl triclosan. Triclosan and methyl triclosan have been detected in water, sediment, fish and invertebrates near sewage treatment facilities. Understanding the biotransformation of methyl triclosan and triclosan in a model food fish, the channel catfish, will be of value in assessing the likelihood that these compounds will bioaccumulate in exposed fish, and therefore potentially pass up the food chain. We hypothesize that cytochrome P450 will catalyze the O-demethylation of methyl triclosan to yield triclosan, which is likely to undergo glucuronidation or sulfonation of the phenolic hydroxyl group. Conversion of methyl triclosan to triclosan was measured by LC/MS/MS following aerobic incubation of varying concentrations of methyl triclosan with NADPH and hepatic and intestinal microsomes from untreated, 3-methylcholanthrene-treated (10 mg/kg, i.p.) or PCB-126-treated (0.1 mg/kg, i.p.) channel catfish (n=4 per treatment group). The K(m) values for methyl triclosan were similar for untreated, 3-methylcholanthrene-treated and PCB-126-treated catfish liver microsomes, ranging from 80 to 250 ?M. V(max) values for O-demethylation ranged from 30 to 150 pmol/min/mg protein, with no significant differences between controls, PCB-126-treated or 3-methylcholanthrene-treated fish, suggesting that methyl triclosan O-demethylation was not a CYP1-catalyzed reaction. Methyl triclosan O-demethylation activities in intestinal microsomes were similar to or lower than those found with liver microsomes. The calculated rate of O-demethylation of methyl triclosan in catfish liver at 1 ?M, a concentration reported in exposed fish, and 21°C, an early summer water temperature, is 0.10 pmol/min/mg protein. This slow rate of metabolism suggests that upon continued exposure, methyl triclosan may bioaccumulate in the channel catfish. Triclosan itself, however, was readily glucuronidated by hepatic and intestinal microsomes and sulfonated by hepatic and intestinal cytosol. Triclosan glucuronidation followed Michaelis-Menten kinetics when rates were measured across a concentration range of 5-1000 ?M, whereas triclosan sulfonation exhibited substrate inhibition at concentrations above 10-20 ?M in both intestinal and hepatic cytosol. Based on the enzyme kinetic constants measured in hepatic and intestinal fractions at 21°C, triclosan at 1 ?M could be glucuronidated at rates of 23 and 3.2 pmol/min/mg protein respectively in liver and intestine, and sulfonated at rates of 277 (liver) and 938 (intestine) pmol/min/mg protein. These rates are much higher than the rates of demethylation of methyl triclosan, and suggest that triclosan would be rapidly cleared and unlikely to bioaccumulate in catfish tissues. PMID:22926334

James, Margaret O; Marth, Christopher J; Rowland-Faux, Laura

2012-11-15

406

Postharvest control of western flower thrips (Thysanoptera: Thripidae) and California red scale (Hemiptera: Diaspididae) with ethyl formate and its impact on citrus fruit quality.  

PubMed

The postharvest control of arthropod pests is a challenge that the California citrus industry must overcome when exporting fruit overseas. Currently, methyl bromide fumigation is used to control postharvest pests on exported citrus, but it may soon be unavailable because of use restrictions and cost of this health-hazard ozone-depleting chemical. Ethyl formate is a natural plant volatile and possible alternative to methyl bromide in postharvest insect control. The objectives of this study were 1) to evaluate the mortality of third instar California red scale [Aonidiella aurantii (Maskell)] (Hemiptera: Diaspididae) and adult western flower thrips [Frankliniella occidentalis (Pergande)] (Thysanoptera: Thripidae) under a wide range of ethyl formate concentrations, 2) to determine the ethyl formate concentration required to reach a Probit 9 level of control for both pests, and 3) to test the effects of ethyl formate fumigation on the quality of navel oranges [Citrus sinensis (L.) Osbeck] and lemons [Citrus limon (L.) Burman f.] at 24 h after fumigation, and at different time periods to simulate shipping plus storage (5 wk at 5 degrees C), and shipping, storage, handling, and shelf-life (5 wk at 5 degrees C, plus 5 d at 15 degrees C, and 2 d at 20 degrees C). The results indicate that ethyl formate is a promising alternative to methyl bromide for the California citrus industry, because of successful control of adult western flower thips and third instar California red scale and no deleterious effect on fruit quality at any of the evaluated periods and quality parameters. PMID:24498732

Pupin, Francine; Bikoba, Veronique; Biasi, William B; Pedroso, Gabriel M; Ouyang, Yuling; Grafton-Cardwell, Elizabeth E; Mitcham, Elizabeth J

2013-12-01

407

Diffusion of 1-Ethyl-3-methyl-imidazolium Acetate in Glucose, Cellobiose, and Cellulose Solutions  

PubMed Central

Solutions of glucose, cellobiose and microcrystalline cellulose in the ionic liquid 1-ethyl-3-methyl-imidazolium ([C2mim][OAc]) have been examined using pulsed-field gradient 1H NMR. Diffusion coefficients of the cation and anion across the temperature range 20–70 °C have been determined for a range of concentrations (0–15% w/w) of each carbohydrate in [C2mim][OAc]. These systems behave as an “ideal mixture” of free ions and ions that are associated with the carbohydrate molecules. The molar ratio of carbohydrate OH groups to ionic liquid molecules, ?, is the key parameter in determining the diffusion coefficients of the ions. Master curves for the diffusion coefficients of cation, anion and their activation energies are generated upon which all our data collapses when plotted against ?. Diffusion coefficients are found to follow an Arrhenius type behavior and the difference in translational activation energy between free and associated ions is determined to be 9.3 ± 0.9 kJ/mol. PMID:24405090

2014-01-01

408

40 CFR 721.10326 - 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...  

Code of Federal Regulations, 2013 CFR

...2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...2-propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl...

2013-07-01

409

40 CFR 721.10326 - 2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...  

Code of Federal Regulations, 2014 CFR

...2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...2-Propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl 2-propenoate...2-propenoic acid, 2-methyl-, methyl ester, polymer with butyl 2-propenoate, ethyl...

2014-07-01

410

40 CFR 721.10138 - 3-Isoxazolecarboxylic acid, 4,5-dihydro-5,5-diphenyl-, ethyl ester.  

Code of Federal Regulations, 2010 CFR

...5-dihydro-5,5-diphenyl-, ethyl ester. 721.10138 Section 721.10138...5-dihydro-5,5-diphenyl-, ethyl ester. (a) Chemical substance and significant...5-dihydro-5,5-diphenyl-, ethyl ester (PMN P-05-336; CAS No....

2010-07-01

411

40 CFR 721.1950 - 2-Butenedioic acid (Z), mono(2-((1-oxopropenyloxy)ethyl) ester .  

Code of Federal Regulations, 2010 CFR

...mono(2-((1-oxopropenyloxy)ethyl) ester . 721.1950 Section 721.1950 ...mono(2-((1-oxopropenyloxy)ethyl) ester . (a) Chemical substances and significant...mono(2-((1-oxopropenyloxy)ethyl) ester (PMN P-85-543) is subject to...

2010-07-01

412

40 CFR 721.10074 - Acetic acid, 2-chloro-, 1-(3,3-dimethylcyclohexyl)ethyl ester.  

Code of Federal Regulations, 2010 CFR

...1-(3,3-dimethylcyclohexyl)ethyl ester. 721.10074 Section 721.10074...1-(3,3-dimethylcyclohexyl)ethyl ester. (a) Chemical substance and significant...1-(3,3-dimethylcyclohexyl)ethyl ester (PMN P-05-568; CAS No....

2010-07-01

413

21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.  

Code of Federal Regulations, 2012 CFR

...2012-04-01 2012-04-01 false Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane...Paper and Paperboard § 176.160 Chromium (Cr III) complex of N -ethyl-N...heptadecylfluoro-octane sulfonyl glycine. The chromium (Cr III) complex of N- ethyl -...

2012-04-01

414

21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.  

Code of Federal Regulations, 2011 CFR

...2011-04-01 2011-04-01 false Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane...Paper and Paperboard § 176.160 Chromium (Cr III) complex of N -ethyl-N...heptadecylfluoro-octane sulfonyl glycine. The chromium (Cr III) complex of N- ethyl -...

2011-04-01

415

21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.  

Code of Federal Regulations, 2013 CFR

...2013-04-01 2013-04-01 false Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane...Paper and Paperboard § 176.160 Chromium (Cr III) complex of N -ethyl-N...heptadecylfluoro-octane sulfonyl glycine. The chromium (Cr III) complex of N- ethyl -...

2013-04-01

416

21 CFR 176.160 - Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane sulfonyl glycine.  

Code of Federal Regulations, 2014 CFR

...2014-04-01 2014-04-01 false Chromium (Cr III) complex of N-ethyl-N-heptadecylfluoro-octane...Paper and Paperboard § 176.160 Chromium (Cr III) complex of N -ethyl-N...heptadecylfluoro-octane sulfonyl glycine. The chromium (Cr III) complex of N- ethyl -...

2014-04-01

417

Mucor circinelloides whole-cells as a biocatalyst for the production of ethyl esters based on babassu oil.  

PubMed

The intracellular lipase production by Mucor circinelloides URM 4182 was investigated through a step-by-step strategy to attain immobilized whole-cells with high lipase activity. Physicochemical parameters, such as carbon and nitrogen sources, inoculum size and aeration, were studied to determine the optimum conditions for both lipase production and immobilization in polyurethane support. Olive oil and soybean peptone were found to be the best carbon and nitrogen sources, respectively, to enhance the intracellular lipase activity. Low inoculum level and poor aeration rate also provided suitable conditions to attain high lipase activity (64.8 ± 0.8 U g(-1)). The transesterification activity of the immobilized whole- cells was assayed and optimal reaction conditions for the ethanolysis of babassu oil were determined by experimental design. Statistical analysis showed that M. circinelloides whole-cells were able to produce ethyl esters at all tested conditions, with the highest yield attained (98.1 %) at 35 °C using an 1:6 oil-to-ethanol molar ratio. The biocatalyst operational stability was also assayed in a continuous packed bed reactor (PBR) charged with glutaraldehyde (GA) and Aliquat-treated cells revealing half-life of 43.0 ± 0.5 and 20.0 ± 0.8 days, respectively. These results indicate the potential of immobilized M. circinelloides URM 4182 whole-cells as a low-cost alternative to conventional biocatalysts in the production of ethyl esters from babassu oil. PMID:24958521

Andrade, Grazielle S S; Carvalho, Ana K F; Romero, Cintia M; Oliveira, Pedro C; de Castro, Heizir F

2014-12-01

418

Ethyl benzene should be considered ototoxic at occupationally relevant exposure concentrations.  

PubMed

Organic solvents can produce ototoxic effects in both man and experimental animals. The objective of this study was to review the literature on the effects of low-level exposure to ethyl benzene on the auditory system and consider its relevance for the occupational settings. Both human and animal investigations were evaluated only for realistic exposure concentrations based on the permissible exposure limits. In Quebec, the Time-Weighed Average Exposure Value for 8A h (TWAEV) is 100A ppm (434A mg/m(3)) and the Short-Term Exposure Value for 15A min (STEV) is 125A ppm (543A mg/m(3)). In humans, the upper limit for considering ototoxicity data relevant to the occupational exposure situation was set at STEV. Animal data were evaluated only for exposure concentrations up to 100 times the TWAEV. In workers, there is no evidence of either ethyl benzene-induced hearing losses or ototoxic interaction after combined exposure to ethyl benzene and noise. In rats, ethyl benzene affects the auditory function mainly in the cochlear mid-frequency range and ototoxic interaction was observed after combined exposure to noise and ethyl benzene. Further studies with sufficient data on the ethyl benzene exposure of workers are necessary to make a definitive conclusion. Given the current evidence from animal studies, we recommend considering ethyl benzene as an ototoxic agent. PMID:19022877

Vyskocil, A; Leroux, T; Truchon, G; Lemay, F; Gendron, M; Gagnon, F; El Majidi, N; Viau, C

2008-05-01

419

DETERMINATION OF DISSOLVED KEPONE BY DIRECT ADDITION OF XAD-2 RESIN TO WATER  

EPA Science Inventory

Analytical procedures are described for the determination of Kepone in water, using benzene, toulene-ethyl acetate, or ethyl ether-hexane as solvents. The procedure is presently being used to quantify dissolved Kepone concentrations of less than 15 ng/l in the James River and thu...

420

Antioxidant and antimicrobial activities of ethyl acetate extract, fractions and compounds from stem bark of Albizia adianthifolia (Mimosoideae)  

PubMed Central

Background Albizia adianthifolia is used traditionally in Cameroon to treat several ailments, including infectious and associated diseases. This work was therefore designed to investigate the antioxidant and antimicrobial activities of ethyl acetate extract, fractions and compounds isolated from the stem bark of this plant. Methods The plant extract was prepared by maceration in ethyl acetate. Its fractionation was done by column chromatography and the structures of isolated compounds were elucidated using spectroscopic data in conjunction with literature data. The 1,1-diphenyl-2-picrylhydrazyl (DPPH) and trolox equivalent antioxidant capacity (TEAC) assays were used to detect the antioxidant activity. Broth micro-dilution method was used for antimicrobial test. Total phenol content was determined spectrophotometrically in the extracts by using Folin–Ciocalteu method. Results The fractionation of the extract afforded two known compounds: lupeol (1) and aurantiamide acetate (2) together with two mixtures of fatty acids: oleic acid and n-hexadecanoic acid (B1); n-hexadecanoic acid, octadecanoic acid and docosanoic acid (B2). Aurantiamide acetate was the most active compound. The total phenol concentration expressed as gallic acid equivalents (GAE) was found to vary from 1.50 to 13.49??g/ml in the extracts. The antioxidant activities were well correlated with the total phenol content (R2?=?0.946 for the TEAC method and R2?=?0.980 for the DPPH free-radical scavenging assay). Conclusions Our results clearly reveal that the ethyl acetate extract from the stem bark of A. adianthifolia possesses antioxidant and antimicrobial principles. The antioxidant activity of this extract as well as that of compound 2 are being reported herein for the first time. These results provide promising baseline information for the potential use of this plant as well as compound 2 in the treatment of oxidative damage and infections associated with the studied microorganisms. PMID:22809287

2012-01-01