Effects of repeated administration of the monoamine oxidase inhibitor phenelzine on the discriminability of d-lysergic acid diethylamide (LSD) and 1-(m-trifluoromethylphenyl) piperazine (TFMPP).

PubMed

Cunningham, K A; Carroll, B A; Appel, J B

1986-01-01

Rats trained to discriminate d-lysergic acid diethylamide (LSD; 0.08 mg/kg) or 1-(m-trifluoromethylphenyl) piperazine (TFMPP; 0.8 mg/kg) were treated with the monoamine oxidase inhibitor (MAOI) phenelzine (10 mg/kg/day) for 7 days. After a 24 h "washout" period, they were challenged with the training drug (and dose) or saline, during extinction test sessions. Following 0.08 mg/kg LSD, LSD-trained rats responded primarily on the saline lever (29% drug-appropriate responding) while, after TFMPP (0.8 mg/kg), TFMPP-trained animals responded on the drug lever (75% drug-appropriate responding). These preliminary data suggest that, if serotonin receptors are involved in the behavioral effects of TFMPP, these receptors differ from those involved in the effects of LSD.

Modification of 5-methoxy-N,N-dimethyltryptamine-induced hyperactivity by monoamine oxidase A inhibitor harmaline in mice and the underlying serotonergic mechanisms.

PubMed

Jiang, Xi-Ling; Shen, Hong-Wu; Yu, Ai-Ming

2016-06-01

5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and harmaline are indolealkylamine (IAA) drugs often abused together. Our recent studies have revealed the significant effects of co-administered harmaline, a monoamine oxidase inhibitor (MAOI), on 5-MeO-DMT pharmacokinetics and thermoregulation. This study was to delineate the impact of harmaline and 5-MeO-DMT on home-cage activity in mouse models, as well as the contribution of serotonin (5-HT) receptors. Home-cage activities of individual animals were monitored automatically in the home cages following implantation of telemetry transmitters and administration of various doses of IAA drugs and 5-HT receptor antagonists. Area under the effect curve (AUEC) of mouse activity values were calculated by trapezoidal rule. High dose of harmaline (15mg/kg, ip) alone caused an early-phase (0-45min) hypoactivity in mice that was fully attenuated by 5-HT1A receptor antagonist WAY-100635, whereas a late-phase (45-180min) hyperactivity that was reduced by 5-HT2A receptor antagonist MDL-100907. 5-MeO-DMT (10 and 20mg/kg, ip) alone induced biphasic effects, an early-phase (0-45min) hypoactivity that was completely attenuated by WAY-100635, and a late-phase (45-180min) hyperactivity that was fully suppressed by MDL-100907. Interestingly, co-administration of MAOI harmaline (2-15mg/kg) with a subthreshold dose of 5-MeO-DMT (2mg/kg) induced excessive hyperactivities at late phase (45-180min) that could be abolished by either WAY-100635 or MDL-100907. Co-administration of MAOI with 5-MeO-DMT provokes excessive late-phase hyperactivity, which involves the activation of both 5-HT1A and 5-HT2A receptors. Copyright © 2016 Institute of Pharmacology, Polish Academy of Sciences. Published by Elsevier Urban & Partner Sp. z o.o. All rights reserved.

Modification of 5-methoxy-N,N-dimethyltryptamine-induced hyperactivity by monoamine oxidase A inhibitor harmaline in mice and the underlying serotonergic mechanisms

PubMed Central

Jiang, Xi-Ling; Shen, Hong-Wu; Yu, Ai-Ming

2016-01-01

Background 5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) and harmaline are indolealkylamine (IAA) drugs often abused together. Our recent studies have revealed the significant effects of co-administered harmaline, a monoamine oxidase inhibitor (MAOI), on 5-MeO-DMT pharmacokinetics and thermoregulation. This study was to delineate the impact of harmaline and 5-MeO-DMT on home-cage activity in mouse models, as well as the contribution of serotonin (5-HT) receptors. Methods Home-cage activities of individual animals were monitored automatically in the home cages following implantation of telemetry transmitters and administration of various doses of IAA drugs and 5-HT receptor antagonists. Area under the effect curve (AUEC) of mouse activity values were calculated by trapezoidal rule. Results High dose of harmaline (15 mg/kg, ip) alone caused an early-phase (0–45 min) hypoactivity in mice that was fully attenuated by 5-HT1A receptor antagonist WAY-100635, whereas a late-phase (45–180 min) hyperactivity that was reduced by 5-HT2A receptor antagonist MDL-100907. 5-MeO-DMT (10 and 20 mg/kg, ip) alone induced biphasic effects, an early-phase (0–45 min) hypoactivity that was completely attenuated by WAY-100635, and a late-phase (45–180 min) hyperactivity that was fully suppressed by MDL-100907. Interestingly, co-administration of MAOI harmaline (2–15 mg/kg) with a subthreshold dose of 5-MeO-DMT (2 mg/kg) induced excessive hyperactivities at late phase (45–180 min) that could be abolished by either WAY-100635 or MDL-100907. Conclusions Co-administration of MAOI with 5-MeO-DMT provokes excessive late-phase hyperactivity, which involves the activation of both 5-HT1A and 5-HT2A receptors. PMID:26977821

Monoamine Oxidase-A Occupancy by Moclobemide and Phenelzine: Implications for the Development of Monoamine Oxidase Inhibitors.

PubMed

Chiuccariello, Lina; Cooke, Robert G; Miler, Laura; Levitan, Robert D; Baker, Glen B; Kish, Stephen J; Kolla, Nathan J; Rusjan, Pablo M; Houle, Sylvain; Wilson, Alan A; Meyer, Jeffrey H

2015-08-27

Monoamine oxidase inhibitors (MAOIs) are being developed for major depressive disorder, Alzheimer's, and Parkinson's Disease. Newer MAOIs have minimal sensitivity to tyramine, but a key limitation for optimizing their development is that standards for in vivo monoamine oxidase-A (MAO-A) occupancy in humans are not well established. The objectives were to determine the dose-occupancy relationship of moclobemide and the occupancy of phenelzine at typical clinical dosing. Major depressive episode (MDE) subjects underwent [(11)C]harmine positron emission tomography scanning prior to and following 6 weeks of treatment with moclobemide or phenelzine. Mean brain MAO-A occupancies were 74.23±8.32% for moclobemide at 300-600 mg daily (n = 11), 83.75±5.52% for moclobemide at 900-1200 mg daily (n = 9), and 86.82±6.89% for phenelzine at 45-60 mg daily (n = 4). The regional dose-occupancy relationship of moclobemide fit a hyperbolic function [F(x) = a(x/[b + x]); F(1,18) = 5.57 to 13.32, p = 0.002 to 0.03, mean 'a': 88.62±2.38%, mean 'b': 69.88±4.36 mg]. Multivariate analyses of variance showed significantly greater occupancy of phenelzine (45-60mg) and higher-dose moclobemide (900-1200 mg) compared to lower-dose moclobemide [300-600 mg; F(7,16) = 3.94, p = 0.01]. These findings suggest that for first-line MDE treatment, daily moclobemide doses of 300-600mg correspond to a MAO-A occupancy of 74%, whereas for treatment-resistant MDE, either phenelzine or higher doses of moclobemide correspond to a MAO-A occupancy of at least 84%. Therefore, novel MAO inhibitor development should aim for similar thresholds. The findings provide a rationale in treatment algorithm design to raise moclobemide doses to inhibit more MAO-A sites, but suggest switching from high-dose moclobemide to phenelzine is best justified by binding to additional targets. © The Author 2015. Published by Oxford University Press on behalf of the American Association for Public Opinion Research.

Monoamine Oxidase-A Occupancy by Moclobemide and Phenelzine: Implications for the Development of Monoamine Oxidase Inhibitors

PubMed Central

Chiuccariello, Lina; Cooke, Robert G; Miler, Laura; Levitan, Robert D; Baker, Glen B; Kish, Stephen J; Kolla, Nathan J; Rusjan, Pablo M; Houle, Sylvain; Wilson, Alan A

2016-01-01

Background: Monoamine oxidase inhibitors (MAOIs) are being developed for major depressive disorder, Alzheimer’s, and Parkinson’s Disease. Newer MAOIs have minimal sensitivity to tyramine, but a key limitation for optimizing their development is that standards for in vivo monoamine oxidase-A (MAO-A) occupancy in humans are not well established. The objectives were to determine the dose-occupancy relationship of moclobemide and the occupancy of phenelzine at typical clinical dosing. Methods: Major depressive episode (MDE) subjects underwent [11C]harmine positron emission tomography scanning prior to and following 6 weeks of treatment with moclobemide or phenelzine. Results: Mean brain MAO-A occupancies were 74.23±8.32% for moclobemide at 300–600mg daily (n = 11), 83.75±5.52% for moclobemide at 900–1200mg daily (n = 9), and 86.82±6.89% for phenelzine at 45–60mg daily (n = 4). The regional dose-occupancy relationship of moclobemide fit a hyperbolic function [F(x) = a(x/[b + x]); F(1,18) = 5.57 to 13.32, p = 0.002 to 0.03, mean ‘a’: 88.62±2.38%, mean ‘b’: 69.88±4.36 mg]. Multivariate analyses of variance showed significantly greater occupancy of phenelzine (45–60mg) and higher-dose moclobemide (900–1200mg) compared to lower-dose moclobemide [300–600mg; F(7,16) = 3.94, p = 0.01]. Conclusions: These findings suggest that for first-line MDE treatment, daily moclobemide doses of 300–600mg correspond to a MAO-A occupancy of 74%, whereas for treatment-resistant MDE, either phenelzine or higher doses of moclobemide correspond to a MAO-A occupancy of at least 84%. Therefore, novel MAO inhibitor development should aim for similar thresholds. The findings provide a rationale in treatment algorithm design to raise moclobemide doses to inhibit more MAO-A sites, but suggest switching from high-dose moclobemide to phenelzine is best justified by binding to additional targets. PMID:26316187

Effects of monoamine oxidase inhibitor and cytochrome P450 2D6 status on 5-Methoxy-N,N-dimethyltryptamine Metabolism and Pharmacokinetics

PubMed Central

Shen, Hong-Wu; Wu, Chao; Jiang, Xi-Ling; Yu, Ai-Ming

2010-01-01

5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a natural psychoactive indolealkylamine drug that has been used for recreational purpose. Our previous study revealed that polymorphic cytochrome P450 2D6 (CYP2D6) catalyzed 5-MeO-DMT O-demethylation to produce active metabolite bufotenine, while 5-MeO-DMT is mainly inactivated through deamination pathway mediated by monoamine oxidase (MAO). This study, therefore, aimed to investigate the impact of CYP2D6 genotype/phenotype status and MAO inhibitor (MAOI) on 5-MeO-DMT metabolism and pharmacokinetics. Enzyme kinetic studies using recombinant CYP2D6 allelic isozymes showed that CYP2D6.2 and CYP2D6.10 exhibited 2.6- and 40-fold lower catalytic efficiency (Vmax/Km), respectively, in producing bufotenine from 5-MeO-DMT, compared with wild-type CYP2D6.1. When co-incubated with MAOI pargyline, 5-MeO-DMT O-demethylation in 10 human liver microsomes showed significantly strong correlation with bufuralol 1’-hydroxylase activities (R² = 0.98; p < 0.0001) and CYP2D6 contents (R² = 0.77; p = 0.0007), whereas no appreciable correlations with enzymatic activities of other P450 enzymes. Furthermore, concurrent MAOI harmaline sharply reduced 5-MeO-DMT depletion and increased bufotenine formation in human CYP2D6 extensive metabolizer hepatocytes. In vivo studies in wild-type and CYP2D6-humanized (Tg-CYP2D6) mouse models showed that Tg-CYP2D6 mice receiving the same dose of 5-MeO-DMT (20 mg/kg, i.p.) had 60% higher systemic exposure to metabolite bufotenine. In addition, pre-treatment of harmaline (5 mg/kg, i.p.) led to 3.6- and 4.4-fold higher systemic exposure to 5-MeO-DMT (2 mg/kg, i.p.), and 9.9- and 6.1-fold higher systemic exposure to bufotenine in Tg-CYP2D6 and wild-type mice, respectively. These findings indicate that MAOI largely affects 5-MeO-DMT metabolism and pharmacokinetics, as well as bufotenine formation that is mediated by CYP2D6. PMID:20206139

Effects of monoamine oxidase inhibitor and cytochrome P450 2D6 status on 5-methoxy-N,N-dimethyltryptamine metabolism and pharmacokinetics.

PubMed

Shen, Hong-Wu; Wu, Chao; Jiang, Xi-Ling; Yu, Ai-Ming

2010-07-01

5-Methoxy-N,N-dimethyltryptamine (5-MeO-DMT) is a natural psychoactive indolealkylamine drug that has been used for recreational purpose. Our previous study revealed that polymorphic cytochrome P450 2D6 (CYP2D6) catalyzed 5-MeO-DMT O-demethylation to produce active metabolite bufotenine, while 5-MeO-DMT is mainly inactivated through deamination pathway mediated by monoamine oxidase (MAO). This study, therefore, aimed to investigate the impact of CYP2D6 genotype/phenotype status and MAO inhibitor (MAOI) on 5-MeO-DMT metabolism and pharmacokinetics. Enzyme kinetic studies using recombinant CYP2D6 allelic isozymes showed that CYP2D6.2 and CYP2D6.10 exhibited 2.6- and 40-fold lower catalytic efficiency (V(max)/K(m)), respectively, in producing bufotenine from 5-MeO-DMT, compared with wild-type CYP2D6.1. When co-incubated with MAOI pargyline, 5-MeO-DMT O-demethylation in 10 human liver microsomes showed significantly strong correlation with bufuralol 1'-hydroxylase activities (R(2)=0.98; P<0.0001) and CYP2D6 contents (R(2)=0.77; P=0.0007), whereas no appreciable correlations with enzymatic activities of other P450 enzymes. Furthermore, concurrent MAOI harmaline sharply reduced 5-MeO-DMT depletion and increased bufotenine formation in human CYP2D6 extensive metabolizer hepatocytes. In vivo studies in wild-type and CYP2D6-humanized (Tg-CYP2D6) mouse models showed that Tg-CYP2D6 mice receiving the same dose of 5-MeO-DMT (20mg/kg, i.p.) had 60% higher systemic exposure to metabolite bufotenine. In addition, pretreatment of harmaline (5mg/kg, i.p.) led to 3.6- and 4.4-fold higher systemic exposure to 5-MeO-DMT (2mg/kg, i.p.), and 9.9- and 6.1-fold higher systemic exposure to bufotenine in Tg-CYP2D6 and wild-type mice, respectively. These findings indicate that MAOI largely affects 5-MeO-DMT metabolism and pharmacokinetics, as well as bufotenine formation that is mediated by CYP2D6. (c) 2010 Elsevier Inc. All rights reserved.

Efficacy of citalopram and moclobemide in patients with social phobia: some preliminary findings.

PubMed

Atmaca, Murad; Kuloglu, Murat; Tezcan, Ertan; Unal, Ahmet

2002-12-01

The efficacy of irreversible and reversible monoamine oxidase inhibitors (MAOIs) in the treatment of social phobia (SP) is well established. Recently, selective serotonin reuptake inhibitors (SSRIs) have been used more frequently. In the present study, the efficacy and side-effect profile of citalopram, an SSRI, and moclobemide, the only MAOI used in Turkey, were compared. The 71 patients diagnosed with SP according to DSM-III-R were randomly assigned to two subgroups; citalopram (n = 36) or moclobemide (n = 35). The study was an 8-week, randomized, open-label, rater-blinded, parallel-group trial. All patients were assessed by Hamilton anxiety rating (HAM-A), Liebowitz social anxiety (LSAS), clinical global impression-severity of illness (CGI-SI) and clinical global impression-improvement (CGI-I) scales. There was a similar percentage of responders (citalopram 75%, n = 27 and moclobemide 74.3%, n = 26), with a >50% or greater reduction in LSAS total score and ratings of "very much" or "much improved" on the CGI-I. None of the patients withdrew from the study. The results of the present study suggest that citalopram has shown promising results in patients with SP. Copyright 2002 John Wiley & Sons, Ltd.

Tramadol and another atypical opioid meperidine have exaggerated serotonin syndrome behavioral effects, but decreased analgesic effects, in genetically-deficient serotonin transporter (SERT) mice

PubMed Central

Fox, Meredith A.; Jensen, Catherine L.; Murphy, Dennis L.

2009-01-01

The serotonin syndrome is a potential side effect of serotonin-enhancing drugs, including antidepressants such as selective serotonin reuptake inhibitors (SSRIs) and monoamine oxidase inhibitors (MAOIs). We recently reported a genetic mouse model for the serotonin syndrome, as serotonin transporter (SERT)-deficient mice have exaggerated serotonin syndrome behavioral responses to the MAOI tranylcypromine and the serotonin precursor 5-hydroxy-L-tryptophan (5-HTP). As numerous case reports implicate the atypical opioids tramadol and meperidine in the development of the human serotonin syndrome, we examined tramadol and meperidine as possible causative drugs in the rodent model of the serotonin syndrome in SERT wildtype (+/+), heterozygous (+/−) and knockout (−/−) mice. Comparisons were made to SERT mice treated with either vehicle or morphine, an opioid not implicated in the serotonin syndrome in humans. Here we show that tramadol and meperidine, but not morphine, induce serotonin syndrome-like behaviors in mice, and we show that this response is exaggerated in mice lacking one or two copies of SERT. The exaggerated response to tramadol in SERT −/− mice was blocked by pretreatment with the 5-HT1A antagonist WAY 100635. Further, we show that morphine-, meperidine- and tramadol-induced analgesia is markedly decreased in SERT −/− mice. These studies suggest that caution seems warranted in prescribing or not warning patients receiving SSRIs or MAOIs, that dangerous side effects may occur during concurrent use of tramadol and similar agents. These findings suggest that it is conceivable that there might be increased vulnerability in individuals with SERT polymorphisms that may reduce SERT by more than 50%, the level in SERT +/− mice. PMID:19275775

Developments in harmine pharmacology--implications for ayahuasca use and drug-dependence treatment.

PubMed

Brierley, Daniel I; Davidson, Colin

2012-12-03

Ayahuasca is a hallucinogenic botanical mixture originating in the Amazon area where it is used ritually, but is now being taken globally. The 2 main constituents of ayahuasca are N,N-dimethyltryptamine (DMT), a hallucinogen, and harmine, a monoamine oxidase inhibitor (MAOI) which attenuates the breakdown of DMT, which would otherwise be broken down very quickly after oral consumption. Recent developments in ayahuasca use include the sale of these compounds on the internet and the substitution of related botanical (anahuasca) or synthetic (pharmahuasca) compounds to achieve the same desired hallucinogenic effects. One intriguing result of ayahuasca use appears to be improved mental health and a reduction in recidivism to alternate (alcohol, cocaine) drug use. In this review we discuss the pharmacology of ayahuasca, with a focus on harmine, and suggest pharmacological mechanisms for the putative reduction in recidivism to alcohol and cocaine misuse. These pharmacological mechanisms include MAOI, effects at 5-HT(2A) and imidazoline receptors and inhibition of dual-specificity tyrosine-phosphorylation regulated kinase 1A (DYRK1A) and the dopamine transporter. We also speculate on the therapeutic potential of harmine in other CNS conditions. Copyright © 2012 Elsevier Inc. All rights reserved.

Drug interactions between hormonal contraceptives and psychotropic drugs: a systematic review.

PubMed

Berry-Bibee, Erin N; Kim, Myong-Jin; Simmons, Katharine B; Tepper, Naomi K; Riley, Halley E M; Pagano, H Pamela; Curtis, Kathryn M

2016-12-01

To examine whether the co-administration of hormonal contraceptives (HC) and psychotropic drugs commonly used to treat anxiety and/or depression results in safety or efficacy concerns for either drug. We searched PubMed and Cochrane libraries for clinical or pharmacokinetic (PK) studies that examined co-administration of any HC with psychotropic drugs [selective serotonin reuptake inhibitors (SSRIs), serotonin-norepinephrine reuptake inhibitors (SNRIs), tricyclic antidepressants (TCAs), oral benzodiazepines, bupropion, mirtazapine, trazadone, buspirone, hydroxyzine, monoamine oxidase inhibitors (MAOIs), or atypical antipsychotics] in reproductive aged women. Of 555 articles identified, 22 articles (18 studies) met inclusion criteria. We identified 5 studies on SSRIs, four on TCAs, one on bupropion, three on atypical antipsychotics and five on oral benzodiazepines. No articles met inclusion criteria for SNRIs, mirtazapine, trazadone, buspirone, hydroxyzine or MAOIs. Overall, clinical studies did not demonstrate differences in unintended pregnancy rates when HCs were administered with and without psychotropic drugs or in psychotropic drug treatment outcomes when psychotropic drugs were administered with and without HCs. PK studies did not demonstrate changes in drug exposure related to contraceptive safety, contraceptive effectiveness or psychotropic drug effectiveness for most classes of psychotropic drugs. However, limited PK data raise concern for HCs increasing systemic exposure of amitriptyline and imipramine (both TCAs), theoretically posing safety concerns. Limited quality and quantity evidence on use of psychotropic drugs and HCs suggests low concern for clinically significant interactions, though no data exist specifically for non-oral formulations of HC. Given the high frequency of use for both HCs and psychotropic drugs among reproductive-age women in the US, this review highlights a need for further research in this area. Copyright © 2016 Elsevier Inc. All rights reserved.

Ionization pattern obtained in electrospray ionization or atmospheric pressure chemical ionization interfaces for authorized antidepressants in Romania

NASA Astrophysics Data System (ADS)

Grecu, Iulia; Ionicǎ, Mihai; Vlǎdescu, Marian; Truţǎ, Elena; Sultan, Carmen; Viscol, Oana; Horhotǎ, Luminiţa; Radu, Simona

2016-12-01

Antidepressants were found in 1950. In the 1990s there was a new generation of antidepressants. They act on the level of certain neurotransmitters extrasinpatic by its growth. After their mode of action antidepressants may be: SSRIs (Selective Serotonin Reuptake Inhibitors); (Serotonin-Norepinephrine Reuptake Inhibitors); SARIs (Serotonin Antagonist Reuptake Inhibitors); NRIs (Norepinephrine Reuptake Inhibitors); NDRIs (Norepinephrine-Dopamine Reuptake Inhibitors) NDRAs (Norepinephrine-Dopamine Releasing Agents); TCAs (Tricyclic Antidepressants); TeCAs (Tetracyclic Antidepressants); MAOIs (Monoamine Oxidase Inhibitors); agonist receptor 5-HT1A (5- hydroxytryptamine); antagonist receptor 5-HT2; SSREs (Selective Serotonin Reuptake Enhancers) and Sigma agonist receptor. To determine the presence of antidepressants in biological products, it has been used a system HPLC-MS (High Performance Liquid Chromatography - Mass Spectrometry) Varian 12001. The system is equipped with APCI (Atmospheric Pressure Chemical Ionization) or ESI (ElectroSpray Ionization) interface. To find antidepressants in unknown samples is necessary to recognize them after mass spectrum. Because the mass spectrum it is dependent on obtaining private parameters work of HPLC-MS system, and control interfaces, the mass spectra library was filled with the mass spectra of all approved antidepressants in Romania. The paper shows the mass spectra obtained in the HPLCMS system.

Social phobia: diagnosis and epidemiology, neurobiology and pharmacology, comorbidity and treatment.

PubMed

Brunello, N; den Boer, J A; Judd, L L; Kasper, S; Kelsey, J E; Lader, M; Lecrubier, Y; Lepine, J P; Lydiard, R B; Mendlewicz, J; Montgomery, S A; Racagni, G; Stein, M B; Wittchen, H U

2000-10-01

Social phobia is a common disorder associated with significant psychosocial impairment, representing a substantial public health problem largely determined by the high prevalence, and the lifelong chronicity. Social phobia starts in early childhood or adolescence and is often comorbid with depression, other anxiety disorders, alcohol and substance abuse or eating disorders. This cascade of comorbidity, usually secondary to social phobia, increases the disability associated with the condition. The possibility that social phobia may be a trigger for later developing comorbid disorders directs attention to the need for early effective treatment as a preventive measure. The most recent drug class to be investigated for the psychopharmacological treatment of social phobia is the SSRI group for which there is growing support. The other drug classes that have been evaluated are monoamine oxidase inhibitors (MAOIs), benzodiazepines, and beta-blockers. The SSRIs represent a new and attractive therapeutic choice for patients with generalized social phobia. Recently the first, large scale, placebo-controlled study to assess the efficacy of drug treatment in generalized social phobia has been completed with paroxetine. Paroxetine was more effective in reducing the symptoms than placebo and was well tolerated. Many now regard SSRIs as the drugs of choice in social phobia because of their effectiveness and because they avoid the problems of treatment with benzodiazepines or classical MAOIs.

Association of MAOA gene functional promoter polymorphism with CSF dopamine turnover and atypical depression.

PubMed

Aklillu, Eleni; Karlsson, Sara; Zachrisson, Olof O; Ozdemir, Vural; Agren, Hans

2009-04-01

Monoamine oxidase-A (MAO-A) is a key mitochondrial enzyme that metabolizes biogenic amine neurotransmitters such as dopamine and serotonin. Individuals with atypical depression (AD) are particularly responsive to treatment with MAO inhibitors (MAOIs). Biomarker tests are essential for prompt diagnosis of AD, and to identify those with an altered brain neurotransmitter metabolism who may selectively respond to MAOI therapy. In a sample of 118 Scandinavian patients with treatment-resistant depression who are naive to MAOI therapy, we investigated the associations between a common MAOA functional promoter polymorphism (MAOA-uVNTR), cerebrospinal fluid (CSF) neurotransmitter metabolites, and AD susceptibility. The metabolites for dopamine (homovanillic acid, HVA), serotonin (5-hydroxyindoleacetic acid) and noradrenaline (3-methoxy-4-hydroxyphenylglycol) were measured in the CSF. AD was associated with the female sex and a higher HVA in CSF (P=0.008). The carriers of the MAOA-uVNTR short allele were significantly overrepresented among women with AD (P=0.005; odds ratio=4.76; 95% confidence interval=1.5-13.1; statistical power=80.0%). Moreover, the MAOA-uVNTR genotype significantly influenced the HVA concentration (P=0.01) and showed a strong trend in relation to 5-hydroxyindoleacetic acid concentration (P=0.057) in women. The mediational statistical analyses showed the CSF-HVA concentration as a key driver of the relationship between MAOA-uVNTR genotype and AD. The association of the MAOA-uVNTR with both susceptibility to AD and dopamine metabolite (HVA) concentration lends further biological plausibility for high MAO-A enzyme activity as a mechanistic factor for genetic predisposition to AD through altered dopamine turnover. Our observations provide new evidence on the in-vivo functional significance of the MAOA-uVNTR short allele as a high activity variant.

Clinical and physiological consequences of rapid tryptophan depletion.

PubMed

Moore, P; Landolt, H P; Seifritz, E; Clark, C; Bhatti, T; Kelsoe, J; Rapaport, M; Gillin, J C

2000-12-01

We review here the rapid tryptophan depletion (RTD) methodology and its controversial association with depressive relapse. RTD has been used over the past decade to deplete serotonin (5-hydroxy-tryptamine, or 5-HT) in humans and to probe the role of the central serotonin system in a variety of psychiatric conditions. Its current popularity was stimulated by reports that RTD reversed the antidepressant effects of selective serotonin reuptake inhibitors (SSRIs) and monoamine oxidase inhibitors (MAOIs) in remitted patients with a history of depression but not in patients treated with antidepressants which promote catecholaminergic rather than serotonergic neurotransmission (such as tricyclic antidepressants or buproprion). However, RTD has inconsistent effects in terms of full clinical relapse in depressed patients. Pooling the data from all published reports, patients who are either unmedicated and/or fully remitted are much less likely to experience relapse (7 of 61, or approximately 9%) than patients who are recently medicated and partially remitted (63 of 133, or approximately 47%; although, the numbers here may reflect patient overlap between reports). Recently remitted patients who have been treated with non-pharmacological therapies such as total sleep deprivation, electroconvulsive therapy, or bright light therapy also do not commonly show full clinical relapse with RTD. We briefly review RTD effects in other psychiatric disorders, many of which are treated with SSRIs. There is accumulating evidence to suggest that RTD affects central serotonergic neurotransmission. Nevertheless, many questions remain about the ability of RTD to reverse the beneficial effects of SSRIs or MAOIs, or to induce symptoms in unmedicated symptomatic or asymptomatic patients.

Hypothesis: The Psychedelic Ayahuasca Heals Traumatic Memories via a Sigma 1 Receptor-Mediated Epigenetic-Mnemonic Process.

PubMed

Inserra, Antonio

2018-01-01

Ayahuasca ingestion modulates brain activity, neurotransmission, gene expression and epigenetic regulation. N,N -Dimethyltryptamine (DMT, one of the alkaloids in Ayahuasca) activates sigma 1 receptor (SIGMAR1) and others. SIGMAR1 is a multi-faceted stress-responsive receptor which promotes cell survival, neuroprotection, neuroplasticity, and neuroimmunomodulation. Simultaneously, monoamine oxidase inhibitors (MAOIs) also present in Ayahuasca prevent the degradation of DMT. One peculiarity of SIGMAR1 activation and MAOI activity is the reversal of mnemonic deficits in pre-clinical models. Since traumatic memories in post-traumatic stress disorder (PTSD) are often characterised by "repression" and PTSD patients ingesting Ayahuasca report the retrieval of such memories, it cannot be excluded that DMT-mediated SIGMAR1 activation and the concomitant MAOIs effects during Ayahuasca ingestion might mediate such "anti-amnesic" process. Here I hypothesise that Ayahuasca, via hyperactivation of trauma and emotional memory-related centres, and via its concomitant SIGMAR1- and MAOIs- induced anti-amnesic effects, facilitates the retrieval of traumatic memories, in turn making them labile (destabilised). As Ayahuasca alkaloids enhance synaptic plasticity, increase neurogenesis and boost dopaminergic neurotransmission, and those processes are involved in memory reconsolidation and fear extinction, the fear response triggered by the memory can be reprogramed and/or extinguished. Subsequently, the memory is stored with this updated significance. To date, it is unclear if new memories replace, co-exist with or bypass old ones. Although the mechanisms involved in memory are still debated, they seem to require the involvement of cellular and molecular events, such as reorganisation of homo and heteroreceptor complexes at the synapse, synaptic plasticity, and epigenetic re-modulation of gene expression. Since SIGMAR1 mobilises synaptic receptor, boosts synaptic plasticity and modulates epigenetic processes, such effects might be involved in the reported healing of traumatic memories in PTSD patients. If this theory proves to be true, Ayahuasca could come to represent the only standing pharmacological treatment which targets traumatic memories in PTSD. Lastly, since SIGMAR1 activation triggers both epigenetic and immunomodulatory programmes, the mechanism here presented could help understanding and treating other conditions in which the cellular memory is dysregulated, such as cancer, diabetes, autoimmune and neurodegenerative pathologies and substance addiction.

Harmane inhibits serotonergic dorsal raphe neurons in the rat.

PubMed

Touiki, Khalid; Rat, Pascal; Molimard, Robert; Chait, Abderrahman; de Beaurepaire, Renaud

2005-11-01

Harmane and norharmane (two beta-carbolines) are tobacco components or products. The effects of harmane and norharmane on serotonergic raphe neurons remain unknown. Harmane and norharmane are inhibitors of the monoamine oxidases A (MAO-A) and B (MAO-B), respectively. To study the effects of harmane, norharmane, befloxatone (MAOI-A), and selegiline (MAOI-B) on the firing of serotonergic neurons. To compare the effects of these compounds to those of nicotine (whose inhibitory action on serotonergic neurons has been previously described). The effects of cotinine, a metabolite of nicotine known to interact with serotonergic systems, are also tested. In vivo electrophysiological recordings of serotonergic dorsal raphe neurons in the anaesthetized rat. Nicotine, harmane, and befloxatone inhibited serotonergic dorsal raphe neurons. The other compounds had no effects. The inhibitory effect of harmane (rapid and long-lasting inhibition) differed from that of nicotine (short and rapidly reversed inhibition) and from that of befloxatone (slow, progressive, and long-lasting inhibition). The inhibitory effects of harmane and befloxatone were reversed by the 5-HT1A antagonist WAY 100 635. Pretreatment of animals with p-chlorophenylalanine abolished the inhibitory effect of befloxatone, but not that of harmane. Nicotine, harmane, and befloxatone inhibit the activity of raphe serotonergic neurons. Therefore, at least two tobacco compounds, nicotine and harmane, inhibit the activity of serotonergic neurons. The mechanism by which harmane inhibits serotonergic dorsal raphe neurons is likely unrelated to a MAO-A inhibitory effect.

Hypothesis: The Psychedelic Ayahuasca Heals Traumatic Memories via a Sigma 1 Receptor-Mediated Epigenetic-Mnemonic Process

PubMed Central

Inserra, Antonio

2018-01-01

Ayahuasca ingestion modulates brain activity, neurotransmission, gene expression and epigenetic regulation. N,N-Dimethyltryptamine (DMT, one of the alkaloids in Ayahuasca) activates sigma 1 receptor (SIGMAR1) and others. SIGMAR1 is a multi-faceted stress-responsive receptor which promotes cell survival, neuroprotection, neuroplasticity, and neuroimmunomodulation. Simultaneously, monoamine oxidase inhibitors (MAOIs) also present in Ayahuasca prevent the degradation of DMT. One peculiarity of SIGMAR1 activation and MAOI activity is the reversal of mnemonic deficits in pre-clinical models. Since traumatic memories in post-traumatic stress disorder (PTSD) are often characterised by “repression” and PTSD patients ingesting Ayahuasca report the retrieval of such memories, it cannot be excluded that DMT-mediated SIGMAR1 activation and the concomitant MAOIs effects during Ayahuasca ingestion might mediate such “anti-amnesic” process. Here I hypothesise that Ayahuasca, via hyperactivation of trauma and emotional memory-related centres, and via its concomitant SIGMAR1- and MAOIs- induced anti-amnesic effects, facilitates the retrieval of traumatic memories, in turn making them labile (destabilised). As Ayahuasca alkaloids enhance synaptic plasticity, increase neurogenesis and boost dopaminergic neurotransmission, and those processes are involved in memory reconsolidation and fear extinction, the fear response triggered by the memory can be reprogramed and/or extinguished. Subsequently, the memory is stored with this updated significance. To date, it is unclear if new memories replace, co-exist with or bypass old ones. Although the mechanisms involved in memory are still debated, they seem to require the involvement of cellular and molecular events, such as reorganisation of homo and heteroreceptor complexes at the synapse, synaptic plasticity, and epigenetic re-modulation of gene expression. Since SIGMAR1 mobilises synaptic receptor, boosts synaptic plasticity and modulates epigenetic processes, such effects might be involved in the reported healing of traumatic memories in PTSD patients. If this theory proves to be true, Ayahuasca could come to represent the only standing pharmacological treatment which targets traumatic memories in PTSD. Lastly, since SIGMAR1 activation triggers both epigenetic and immunomodulatory programmes, the mechanism here presented could help understanding and treating other conditions in which the cellular memory is dysregulated, such as cancer, diabetes, autoimmune and neurodegenerative pathologies and substance addiction. PMID:29674970

Death following acute poisoning by moclobemide.

PubMed

Giroud, Christian; Horisberger, Beat; Eap, Chin; Augsburger, Marc; Ménétrey, Annick; Baumann, Pierre; Mangin, Patrice

2004-02-10

A fatality due to ingestion of a reversible inhibitor of monoamine-oxidase A (MAO-A) is reported. Moclobemide is generally considered as a safe drug far less toxic than tricyclic anti-depressants. However, severe intoxications may result from interactions with other drugs and food such as selective serotonin reuptake inhibitors (SSRIs), anti-Parkinsonians of the MAOI-type (e.g. selegiline) or tyramine from ripe cheese or other sources. In the present case, high levels of moclobemide were measured in peripheral blood exceeding toxic values reported so far in the scientific literature. The body fluid concentrations of moclobemide were of 498 mg/l in peripheral whole blood, 96.3 mg/l in urine while an amount of approximately 33 g could be recovered from gastric contents. The other xenobiotics were considered of little toxicological relevance. The victim (male, 48-year-old) had a past history of depression and committed one suicide attempt 2 years before death. Autopsy revealed no evidence of significant natural disease or injury. It was concluded that the manner of death was suicide and that the unique cause of death was massive ingestion of moclobemide.

Pharmacotherapy for social anxiety disorder (SAnD).

PubMed

Williams, Taryn; Hattingh, Coenraad J; Kariuki, Catherine M; Tromp, Sean A; van Balkom, Anton J; Ipser, Jonathan C; Stein, Dan J

2017-10-19

Recognition is growing that social anxiety disorder (SAnD) is a chronic and disabling disorder, and data from early trials demonstrate that medication may be effective in its treatment. This systematic review is an update of an earlier review of pharmacotherapy of SAnD. To assess the effects of pharmacotherapy for social anxiety disorder in adults and identify which factors (methodological or clinical) predict response to treatment. We searched the Cochrane Common Mental Disorders Controlled Trials Register (CCMDCTR-Studies and CCMDCTR-References) to 17 August 2015. The CCMDCTR contains reports of relevant RCTs from MEDLINE (1950-), Embase (1974-), PsycINFO (1967-) and CENTRAL (all years). We scanned the reference lists of articles for additional studies. We updated the search in August 2017 and placed additional studies in Awaiting Classification, these will be incorporated in the next version of the review, as appropriate. We restricted studies to randomised controlled trials (RCTs) of pharmacotherapy versus placebo in the treatment of SAnD in adults. Two authors (TW and JI) assessed trials for eligibility and inclusion for this review update. We extracted descriptive, methodological and outcome information from each trial, contacting investigators for missing information where necessary. We calculated summary statistics for continuous and dichotomous variables (if provided) and undertook subgroup and sensitivity analyses. We included 66 RCTs in the review (> 24 weeks; 11,597 participants; age range 18 to 70 years) and 63 in the meta-analysis. For the primary outcome of treatment response, we found very low-quality evidence of treatment response for selective serotonin reuptake inhibitors (SSRIs) compared with placebo (number of studies (k) = 24, risk ratio (RR) 1.65; 95% confidence interval (CI) 1.48 to 1.85, N = 4984). On this outcome there was also evidence of benefit for monoamine oxidase inhibitors (MAOIs) (k = 4, RR 2.36; 95% CI 1.48 to 3.75, N = 235), reversible inhibitors of monoamine oxidase A (RIMAs) (k = 8, RR 1.83; 95% CI 1.32 to 2.55, N = 1270), and the benzodiazepines (k = 2, RR 4.03; 95% CI 2.45 to 6.65, N = 132), although the evidence was low quality. We also found clinical response for the anticonvulsants with gamma-amino butyric acid (GABA) analogues (k = 3, RR 1.60; 95% CI 1.16 to 2.20, N = 532; moderate-quality evidence). The SSRIs were the only medication proving effective in reducing relapse based on moderate-quality evidence. We assessed tolerability of SSRIs and the serotonin and norepinephrine reuptake inhibitor (SNRI) venlafaxine on the basis of treatment withdrawal; this was higher for medication than placebo (SSRIs: k = 24, RR 2.59; 95% CI 1.97 to 3.39, N = 5131, low-quality evidence; venlafaxine: k = 4, RR 3.23; 95% CI 2.15 to 4.86, N = 1213, moderate-quality evidence), but there were low absolute rates of withdrawal for both these medications classes compared to placebo. We did not find evidence of a benefit for the rest of the medications compared to placebo.For the secondary outcome of SAnD symptom severity, there was benefit for the SSRIs, the SNRI venlafaxine, MAOIs, RIMAs, benzodiazepines, the antipsychotic olanzapine, and the noradrenergic and specific serotonergic antidepressant (NaSSA) atomoxetine in the reduction of SAnD symptoms, but most of the evidence was of very low quality. Treatment with SSRIs and RIMAs was also associated with a reduction in depression symptoms. The SSRIs were the only medication class that demonstrated evidence of reduction in disability across a number of domains.We observed a response to long-term treatment with medication for the SSRIs (low-quality evidence), for the MAOIs (very low-quality evidence) and for the RIMAs (moderate-quality evidence). We found evidence of treatment efficacy for the SSRIs, but it is based on very low- to moderate-quality evidence. Tolerability of SSRIs was lower than placebo, but absolute withdrawal rates were low.While a small number of trials did report treatment efficacy for benzodiazepines, anticonvulsants, MAOIs, and RIMAs, readers should consider this finding in the context of potential for abuse or unfavourable side effects.

Pharmacological causes of hyperprolactinemia

PubMed Central

Torre, Daria La; Falorni, Alberto

2007-01-01

Hyperprolactinemia is a common endocrinological disorder that may be caused by several physiological and pathological conditions. Several drugs may determine a significant increase in prolactin serum concentration that is frequently associated with symptoms. The so-called typical antipsychotics are frequently responsible for drug-related hyperprolactinemia. Risperidone is one of the atypical neuroleptics most likely to induce hyperprolactinemia, while other atypical drugs are unfrequenlty and only transiently associated with increase of prolactin levels. Women are more sensitive than men to the hyperprolactinemic effect of antipsychotics. Classical and risperidone-induced hyperprolactinemia may be revert when a gradual antipsychotic drug discontinuation is combined with olanzapine or clozapine initiation. Antidepressant drugs with serotoninergic activity, including selective serotonin reuptake inhibitors (SSRI), monoamine oxidase inhibitors (MAO-I) and some tricyclics, can cause hyperprolactinemia. A long list of other compounds may determine an increase in prolactin levels, including prokinetics, opiates, estrogens, anti-androgens, anti-hypertensive drugs, H2-receptor antagonists, anti-convulsivants and cholinomimetics. Finally, hyperprolactinemia has also been documented during conditioning and after autologous blood stem-cell transplantation and during chemotherapy, even though disturbances of prolactin seem to occur less frequently than impairments of the hypothalamus-pituitary-gonad/thyroid axis after intensive treatment and blood marrow transplantation. PMID:18473017

Pharmacological Management of Anxiety Disorders in the Elderly

PubMed Central

Crocco, Elizabeth A.; Jaramillo, Sindy; Cruz-Ortiz, Caroline; Camfield, Katherine

2017-01-01

Opinion Statement Anxiety disorders are common in the elderly. Additionally, anxiety symptoms often accompany co-morbid psychiatric, medical, as well as neurodegenerative diseases in the older population. Anxiety in the elderly, often accompanied by depression, can lead to worsening physical, cognitive and functional impairments in this vulnerable population. Antidepressants are considered first line treatment. Both SSRIs and SNRIs are efficacious and well-tolerated in the elderly. Some SSRIs are strong inhibitors of the cytochrome P450 hepatic pathway whereas others have less potential for drug interaction. Those antidepressants with more favorable pharmacokinetic profiles should be considered first-line in the treatment of anxiety. Mirtazapine and vortioxetine are also considered safe treatment options. Buspirone may have benefit, but lacks studies in elderly populations. Although tricyclic/tetracyclic antidepressants (TCAs) and monoamine oxidase inhibitors (MAOIs) may be effective in the elderly, their side effect and safety profiles are suboptimal and thus are not recommended in late-life. Benzodiazepines and beta blockers should generally be avoided when treating anxiety in the elderly. There is not enough evidence to support the use of antipsychotics or mood stabilizers given their risk of problems in both the long and short term. In addition, antipsychotics have a black box warning for increased mortality in elderly patients with dementia. PMID:28948135

Changing epidemiology of intentional antidepressant drug overdose in Victoria, Australia.

PubMed

Wong, Anselm; Taylor, David McD; Ashby, Karen; Robinson, Jeff

2010-08-01

To determine the epidemiology of intentional antidepressant drug overdose (OD), over an extended time period, in Victoria, Australia. Retrospective epidemiological study of all cases reported to the Victorian Emergency Minimum Dataset (VEMD) January 1998 to December 2007 and calls to the Victorian Poisons Information Centre (VPIC) June 2005 to September 2008. 5467 VEMD cases were analysed. 3169 (57.9%) cases involved selective serotonin reuptake inhibitors (SSRIs) and 1149 (21%) involved tricyclic antidepressants (TCAs). Sertraline (1252, 22.9% cases) was the most common drug. During 2001, the peak year of OD, there were 8.8 OD/100 000 population in the SSRI group and 3.8 OD/100 000 population in the TCA group. Trends over the study period showed increasing SSRI and 'other' newer antidepressant prescription rates and decreases for TCA and monoamine oxidase inhibitors (MAOI). However, the risks of OD in all drug classes were similar and OD/100 000 prescriptions trended downwards for all drug classes over time. 1833 VPIC calls were analysed. Calls relating to SSRIs were the most common yet SSRI OD was associated with significantly fewer symptoms (p < 0.001) and fewer patients with Poisoning Severity Score classifications of moderate or severe (p < 0.01). Antidepressant OD patterns are changing. Antidepressant OD incidence is following prescribing trends. The risk of OD is similar for all drug classes. Absolute numbers of OD and OD/100 000 prescriptions are decreasing for all drug classes.

The predictive validity of atypical neurovegetative depressive symptoms identified by the first principal component in the DUAG trial of moclobemide versus clomipramine.

PubMed

Bech, P; Stage, K B; Larsen, J K; Vestergaard, P; Gram, L F

2012-11-01

To investigate to what extent the primary depression subtype atypical depression can predict differential outcome of the mono-amino-oxidase inhibitor (MAO-I) moclobemide and the tricyclic antidepressant clomipramine in the Danish University Antidepressant Group Study (DUAG). In a randomised, double blind trial, a total of 117 patients with major depression were treated over 6 weeks with either 400 mg moclobemide or 150 mg clomipramine. A baseline principal component analysis (PCA) was performed to identify atypical symptoms on the combined depression scales (Hamilton Depression Scale (HAM-D(17)) and the Quantitative Scale for Atypical Depression (QSAD)). The primary outcome scale was the subscale HAM-D(6) which contains the pure items of depression. PCA identified two items with loadings opposite to the other depression items within HAM-D(17) and QSAD, namely increased duration of sleep and increased appetite (atypical neurovegetative symptoms). Patients with a positive score at baseline on these items were classified as having atypical depression. In total 13 patients were classified as having atypical depression. Within this group of patients 8 received clomipramine and 5 patients received moclobemide. At endpoint the moclobemide treated patients had a significantly better response than the clomipramine treated (P=0.036), effect size 1.42, when using HAM-D(6) as outcome. However, in the 104 patients classified as having typical depression clomipramine was superior to moclobemide (P=0.034), effect size 0.47. The number of patients with atypical neurovegetative symptoms was very small and no placebo arm was included. It is very important to screen for atypical depression (increased duration of sleep/increased appetite) in the acute therapy of patients with major depression. Our results add to the body of evidence that monoamine oxidase inhibitors are superior to tricyclic antidepressants in this sub-group of patients. Copyright © 2012 Elsevier B.V. All rights reserved.

The use of medication in selective mutism: a systematic review.

PubMed

Manassis, Katharina; Oerbeck, Beate; Overgaard, Kristin Romvig

2016-06-01

Despite limited evidence, selective serotonin reuptake inhibitors (SSRIs) and monoamine oxidase inhibitors (MAOIs) are used to reduce symptoms of selective mutism (SM) in children unresponsive to psychosocial interventions. We review existing evidence for the efficacy of these medications, limitations of the literature, and resulting treatment considerations. Bibliographic searches were conducted in Medline, Embase, PsycInfo, Web of Science and Cochrane up to June 2015. Two reviewers independently sought studies of children with SM as primary psychiatric diagnosis, which reported response to medication treatment. Abstracts were limited to those reporting original data. Two reviewers independently assessed the ten papers reporting on >2 subjects regarding study design, key results, and limitations. Heterogeneity of designs mandated a descriptive summary. Symptomatic improvement was found for 66/79 children treated with SSRIs and 4/4 children treated with phenelzine. Only 3/10 studies had unmedicated comparison groups and only two were double-blinded. This review may be affected by publication bias, missed studies, and variability of outcome measures in included studies. Although there is some evidence for symptomatic improvement in SM with medication, especially SSRIs, it is limited by small numbers, lack of comparative trials, lack of consistent measures, and lack of consistent reporting on tolerability. The clinician must weigh this paucity of evidence against the highly debilitating nature of SM, and its adverse effects on the development of those children whose progress with psychosocial interventions is limited or very slow. Studies of optimal dosage and timing of medications in relation to psychosocial treatments are also needed.

N-propargylbenzylamine, a major metabolite of pargyline, is a potent inhibitor of monoamine oxidase type B in rats in vivo: a comparison with deprenyl.

PubMed Central

Karoum, F.

1987-01-01

In an effort to explore the contribution of the metabolites of pargyline towards the in vivo inhibition of monoamine oxidase (MAO), the effects of pargyline and its major metabolites on the production and metabolism of a number of biogenic amines were studied in rats. The administration of pargyline gave rise to three major ethyl acetate extractable metabolites: benzylamine, N-methylbenzylamine and N-propargylbenzylamine (NPB). Only NPB demonstrated in vivo monoamine oxidase inhibitory properties at an acute dose of 30 mg kg-1. The acute effects of pargyline, NPB, and deprenyl on urine and brain concentrations of a number of biogenic amines (phenylethylamine (PEA), m- and p-tyramine, noradrenaline (NA), dopamine, and 5-hydroxytryptamine (5-HT) and their metabolites were evaluated. Increased urine and brain concentrations of PEA were considered to represent in vivo inhibition of type B MAO while decreased concentrations of NA and 5-HT metabolites were regarded as indicators of an in vivo inhibition of MAO type A. NPB, like deprenyl and pargyline, significantly increased urine and brain PEA while only pargyline reduced 5-HT metabolism, suggesting that the metabolism of pargyline to NPB may contribute towards the MAO type B inhibitory effects of pargyline in vivo. Since the therapeutic benefits of MAO inhibitors in clinical practice usually require some period of chronic treatment, the chronic effects of repeated 14 daily doses of the above MAO inhibitors on central and peripheral biogenic amines were evaluated at the following times: during treatment, one day and five days after termination of treatment. The biochemical changes observed during the course of chronic NPB, pargyline and deprenyl treatments generally follow the expected in vitro characteristics of these drugs, but the detailed changes observed suggest clear differences. For example, the in vivo effect of pargyline on urine 5-hydroxyindoleacetic acid excretion was considerably weaker than its effect on the excretion of NA and dopamine metabolites. These changes are opposite to the in vitro effects of pargyline on 5-HT, dopamine and NA oxidative deamination. Inhibitions of the metabolism of all the amines studied were clearly observed during chronic MAOI treatments, but these effects were less evident five days after the end of treatment, suggesting an almost normal metabolism of biogenic amines. It is concluded that while MAO inhibitors may be the primary compound responsible for MAO inhibition, the effects of their metabolites in some cases may also play equally important roles in the regulation of monoamines both in the periphery and the brain.(ABSTRACT TRUNCATED AT 400 WORDS) PMID:3103805

Characterization of the discriminable stimulus produced by 2-BFI: effects of imidazoline I2-site ligands, MAOIs, β-carbolines, agmatine and ibogaine

PubMed Central

MacInnes, Nicholas; Handley, Sheila L

2002-01-01

The molecular nature and functions of the I2 subtype of imidazoline binding sites are unknown but evidence suggests an association with monoamine oxidase (MAO). Rats can distinguish the selective imidazoline I2-site ligand 2-BFI from vehicle in drug discrimination, indicating functional consequences of occupation of these sites. We have used drug discrimination to investigate the nature of the discriminable stimulus, especially in relation to MAO inhibition. Following training to distinguish 2-BFI 7 mg kg−1 i.p. from saline vehicle in two-lever operant-chambers, male Hooded Lister rats underwent sessions where test substances were given instead and the proportion of lever presses on the 2-BFI-associated lever (substitution) recorded. 2-BFI; its cogeners BU216, BU224, BU226 and LSL60101; the reversible MAO-A inhibitors moclobemide and RO41-1049; the β-carbolines harmane, norharmane and harmaline which also reversibly inhibit MAO-A, and the anti-addictive substance ibogaine exhibited potent, dose-dependent substitution for 2-BFI. Agmatine, and LSL60125 substituted at one dose only. The reversible MAO-B inhibitors lazabemide and RO16-1649; the σ2-site ligand SKF10,047 and the I2A-site ligand, amiloride, failed to substitute. The irreversible inhibitor of MAO, deprenyl, substituted for 2-BFI while clorgyline did not. These results suggest imidazoline I2 site ligands produce a common discriminable stimulus that appears associated with reversible inhibition of MAO-A rather than MAO-B, possibly through increases in extracellular concentration of one or more monoamines. Ibogaine exhibits a commonality in its subjective effects with those of I2-site ligands. PMID:11877331

Characterization of the discriminable stimulus produced by 2-BFI: effects of imidazoline I(2)-site ligands, MAOIs, beta-carbolines, agmatine and ibogaine.

PubMed

MacInnes, Nicholas; Handley, Sheila L

2002-03-01

1. The molecular nature and functions of the I(2) subtype of imidazoline binding sites are unknown but evidence suggests an association with monoamine oxidase (MAO). Rats can distinguish the selective imidazoline I(2)-site ligand 2-BFI from vehicle in drug discrimination, indicating functional consequences of occupation of these sites. We have used drug discrimination to investigate the nature of the discriminable stimulus, especially in relation to MAO inhibition. 2. Following training to distinguish 2-BFI 7 mg kg(-1) i.p. from saline vehicle in two-lever operant-chambers, male Hooded Lister rats underwent sessions where test substances were given instead and the proportion of lever presses on the 2-BFI-associated lever (substitution) recorded. 3. 2-BFI; its cogeners BU216, BU224, BU226 and LSL60101; the reversible MAO-A inhibitors moclobemide and RO41-1049; the beta-carbolines harmane, norharmane and harmaline which also reversibly inhibit MAO-A, and the anti-addictive substance ibogaine exhibited potent, dose-dependent substitution for 2-BFI. 4. Agmatine, and LSL60125 substituted at one dose only. The reversible MAO-B inhibitors lazabemide and RO16-1649; the sigma(2)-site ligand SKF10,047 and the I(2A)-site ligand, amiloride, failed to substitute. The irreversible inhibitor of MAO, deprenyl, substituted for 2-BFI while clorgyline did not. 5. These results suggest imidazoline I(2) site ligands produce a common discriminable stimulus that appears associated with reversible inhibition of MAO-A rather than MAO-B, possibly through increases in extracellular concentration of one or more monoamines. Ibogaine exhibits a commonality in its subjective effects with those of I(2)-site ligands.

NADPH oxidase inhibitors: a patent review.

PubMed

Kim, Jung-Ae; Neupane, Ganesh Prasad; Lee, Eung Seok; Jeong, Byeong-Seon; Park, Byung Chul; Thapa, Pritam

2011-08-01

NADPH oxidases, a family of multi-subunit enzyme complexes, catalyze the production of reactive oxygen species (ROS), which may contribute to the pathogenesis of a variety of diseases. In addition to the first NADPH oxidase found in phagocytes, four non-phagocytic NADPH oxidase isoforms have been identified, which all differ in their catalytic subunit (Nox1-5) and tissue distribution. This paper provides a comprehensive review of the patent literature on NADPH oxidase inhibitors, small molecule Nox inhibitors, peptides and siRNAs. Since each member of the NADPH oxidase family has great potential as a therapeutic target, several different compounds have been registered as NADPH oxidase inhibitors in the patent literature. As yet, none have gone through clinical trials, and some have not completed preclinical trials, including safety and specificity evaluation. Recently, small molecule pyrazolopyridine and triazolopyrimidine derivatives have been submitted as potent NADPH oxidase inhibitors and reported as first-in-class inhibitors for idiopathic pulmonary fibrosis and acute stroke, respectively. Further clinical efficacy and safety data are warranted to prove their actual clinical utility.

[Drug treatment of early-stage (de novo and "honeymoon") Parkinson disease].

PubMed

Cesaro, P; Defebvre, L

2014-04-01

In this article, we discuss the management of motor symptoms during the early phases of Parkinson's disease, excluding that of any other clinical manifestation. We relied primarily upon recently published data and do not describe older publications relating to anticholinergic drugs or amantadine. The initial pharmacological treatment of idiopathic Parkinson's disease (IPD) is symptomatic and remains based upon dopaminergic drugs. However, the development of new drugs has broadened the range of strategic options and improved overall patient management. Announcing the diagnosis is a critical moment, as pointed out by patients' associations. Patients should be advised to maintain personal, professional, social and physical activities as long as possible. The potential benefit of early pharmacological treatment should be explained, focusing on the possible disease-modifying effect of drugs such as rasagiline. According to current guidelines, L-Dopa is preferred in patients above 65years of age, while those below 65 should be treated with dopamine agonists. Like monoamine oxidase inhibitors B (MAOI-B), synthetic dopamine agonists exhibit several advantages: easy-to-use treatment with a once-daily administration, delayed L-Dopa initiation, significant efficacy on motor symptoms (although lower than that of L-Dopa). MOAI can be prescribed in association with L-Dopa or dopamine agonists. Rasagiline also delays L-Dopa initiation, and consequently motor complications. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

The increasing role of monoamine oxidase type B inhibitors in Parkinson's disease therapy.

PubMed

Elmer, Lawrence W; Bertoni, John M

2008-11-01

The role of monoamine oxidase type B inhibitors in the treatment of Parkinson's disease has expanded with the new monoamine oxidase B inhibitor rasagiline and a new formulation, selegiline oral disintegrating tablets. As primary therapy in early disease monoamine oxidase B inhibitors reduce motor disability and delay the need for levodopa. In more advanced disease requiring levodopa, adjunctive monoamine oxidase B inhibitors reduce 'off' time and may improve gait and freezing. Rasagiline and selegiline oral disintegrating tablets may reduce the safety risks associated with the amfetamine and methamfetamine metabolites of conventional oral selegiline while retaining or improving therapeutic efficacy. Articles were identified by searches of PubMed and searches on the Internet and reviewed. All articles and other referenced materials were retrieved using the keywords 'Parkinson's disease', 'treatment' and 'monoamine oxidase B inhibitor' and were published between 1960 and 2007, with older references selected for historical significance. Only papers published in English were reviewed. Accumulating data support the use of monoamine oxidase B inhibitors as monotherapy for early and mild Parkinson's disease and as adjunctive therapy for more advanced Parkinson's disease with levodopa-associated motor fluctuations. The recently released monoamine oxidase B inhibitor rasagiline and a new formulation, selegiline oral disintegrating tablets, have potential advantages over conventional oral selegiline.

Bulimia nervosa.

PubMed

Hay, Phillipa J; Bacaltchuk, Josue

2008-06-12

Up to 1% of young women may have bulimia nervosa, characterised by an intense preoccupation with body weight, uncontrolled binge-eating episodes, and use of extreme measures to counteract the feared effects of overeating. People with bulimia nervosa may be of normal weight, making it difficult to diagnose. After ten years, about half of people with bulimia nervosa will have recovered fully, a third will have made a partial recovery, and 10-20% will still have symptoms. We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments for bulimia nervosa in adults? What are the effects of discontinuing treatment in people with bulimia nervosa in remission? We searched: Medline, Embase, The Cochrane Library and other important databases up to June 2007 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). We found 26 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. In this systematic review we present information relating to the effectiveness and safety of the following interventions: cognitive behavioural therapy (alone or plus exposure response prevention enhancement); cognitive orientation therapy; dialectical behavioural therapy; discontinuing fluoxetine in people with remission; guided self-help cognitive behavioural therapy; hypnobehavioural therapy; interpersonal psychotherapy; mirtazapine; monoamine oxidase inhibitors (MAOIs); motivational enhancement therapy; pharmacotherapy plus psychotherapy; pure or unguided self-help cognitive behavioural therapy (CBT); reboxetine; selective serotonin reuptake inhibitors (SSRIs); topiramate; tricyclic antidepressants (TCAs); and venlafaxine.

Bulimia nervosa

PubMed Central

2010-01-01

Introduction Up to 1% of young women may have bulimia nervosa, characterised by an intense preoccupation with body weight, uncontrolled binge-eating episodes, and use of extreme measures to counteract the feared effects of overeating. People with bulimia nervosa may be of normal weight, making it difficult to diagnose. After 10 years, about half of people with bulimia nervosa will have recovered fully, one third will have made a partial recovery, and 10% to 20% will still have symptoms. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments for bulimia nervosa in adults? What are the effects of discontinuing treatment in people with bulimia nervosa in remission? We searched: Medline, Embase, The Cochrane Library, and other important databases up to January 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 27 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: cognitive behavioural therapy (CBT; alone or plus exposure/response prevention enhancement), cognitive orientation therapy, dialectical behavioural therapy, discontinuing fluoxetine in people with remission, guided self-help cognitive behavioural therapy, hypnobehavioural therapy, interpersonal psychotherapy, mirtazapine, monoamine oxidase inhibitors (MAOIs), motivational enhancement therapy, pharmacotherapy plus psychotherapy, pure or unguided self-help cognitive behavioural therapy, reboxetine, selective serotonin reuptake inhibitors (SSRIs), topiramate, tricyclic antidepressants (TCAs), and venlafaxine. PMID:21418667

Bulimia nervosa

PubMed Central

2008-01-01

Introduction Up to 1% of young women may have bulimia nervosa, characterised by an intense preoccupation with body weight, uncontrolled binge-eating episodes, and use of extreme measures to counteract the feared effects of overeating. People with bulimia nervosa may be of normal weight, making it difficult to diagnose. After ten years, about half of people with bulimia nervosa will have recovered fully, a third will have made a partial recovery, and 10-20% will still have symptoms. Methods and outcomes We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments for bulimia nervosa in adults? What are the effects of discontinuing treatment in people with bulimia nervosa in remission? We searched: Medline, Embase, The Cochrane Library and other important databases up to June 2007 (BMJ Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). Results We found 26 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. Conclusions In this systematic review we present information relating to the effectiveness and safety of the following interventions: cognitive behavioural therapy (alone or plus exposure response prevention enhancement); cognitive orientation therapy; dialectical behavioural therapy; discontinuing fluoxetine in people with remission; guided self-help cognitive behavioural therapy; hypnobehavioural therapy; interpersonal psychotherapy; mirtazapine; monoamine oxidase inhibitors (MAOIs); motivational enhancement therapy; pharmacotherapy plus psychotherapy; pure or unguided self-help cognitive behavioural therapy (CBT); reboxetine; selective serotonin reuptake inhibitors (SSRIs); topiramate; tricyclic antidepressants (TCAs); and venlafaxine. PMID:19450294

Bulimia nervosa.

PubMed

Hay, Phillipa J; Claudino, Angélica Medeiros

2010-07-19

Up to 1% of young women may have bulimia nervosa, characterised by an intense preoccupation with body weight, uncontrolled binge-eating episodes, and use of extreme measures to counteract the feared effects of overeating. People with bulimia nervosa may be of normal weight, making it difficult to diagnose. After 10 years, about half of people with bulimia nervosa will have recovered fully, one third will have made a partial recovery, and 10% to 20% will still have symptoms. We conducted a systematic review and aimed to answer the following clinical questions: What are the effects of treatments for bulimia nervosa in adults? What are the effects of discontinuing treatment in people with bulimia nervosa in remission? We searched: Medline, Embase, The Cochrane Library, and other important databases up to January 2010 (Clinical Evidence reviews are updated periodically, please check our website for the most up-to-date version of this review). We included harms alerts from relevant organisations such as the US Food and Drug Administration (FDA) and the UK Medicines and Healthcare products Regulatory Agency (MHRA). We found 27 systematic reviews, RCTs, or observational studies that met our inclusion criteria. We performed a GRADE evaluation of the quality of evidence for interventions. In this systematic review we present information relating to the effectiveness and safety of the following interventions: cognitive behavioural therapy (CBT; alone or plus exposure/response prevention enhancement), cognitive orientation therapy, dialectical behavioural therapy, discontinuing fluoxetine in people with remission, guided self-help cognitive behavioural therapy, hypnobehavioural therapy, interpersonal psychotherapy, mirtazapine, monoamine oxidase inhibitors (MAOIs), motivational enhancement therapy, pharmacotherapy plus psychotherapy, pure or unguided self-help cognitive behavioural therapy, reboxetine, selective serotonin reuptake inhibitors (SSRIs), topiramate, tricyclic antidepressants (TCAs), and venlafaxine.

Study on the activity of non-purine xanthine oxidase inhibitor by 3D-QSAR modeling and molecular docking

NASA Astrophysics Data System (ADS)

Li, Peizhen; Tian, Yueli; Zhai, Honglin; Deng, Fangfang; Xie, Meihong; Zhang, Xiaoyun

2013-11-01

Non-purine derivatives have been shown to be promising novel drug candidates as xanthine oxidase inhibitors. Based on three-dimensional quantitative structure-activity relationship (3D-QSAR) methods including comparative molecular field analysis (CoMFA) and comparative molecular similarity indices analysis (CoMSIA), two 3D-QSAR models for a series of non-purine xanthine oxidase (XO) inhibitors were established, and their reliability was supported by statistical parameters. Combined 3D-QSAR modeling and the results of molecular docking between non-purine xanthine oxidase inhibitors and XO, the main factors that influenced activity of inhibitors were investigated, and the obtained results could explain known experimental facts. Furthermore, several new potential inhibitors with higher activity predicted were designed, which based on our analyses, and were supported by the simulation of molecular docking. This study provided some useful information for the development of non-purine xanthine oxidase inhibitors with novel structures.

Determination of Monoamine Oxidase A and B Activity in Long-Term Treated Patients With Parkinson Disease.

PubMed

Müller, Thomas; Riederer, Peter; Grünblatt, Edna

Biogenic amines and monoamine oxidase inhibitors influence peripheral monoamine oxidase enzyme activity in chronic levodopa/dopa decarboxylase inhibitor-treated patients with Parkinson disease. Rasagiline is an irreversible inhibitor of monoamine oxidase B. Safinamide blocks this isoenzyme in a reversible fashion. The aim of this study was to determine monoamine oxidase A (plasma) and B (platelets) enzyme activity in long-term levodopa-treated patients without and with additional oral intake of 50- or 100-mg safinamide or 1-mg rasagiline or first-time intake of rasagiline. Monoamine oxidase A enzyme activity did not differ between all groups. Patients on rasagiline or safinamide showed lower monoamine oxidase-B enzyme activity compared with patients without monoamine oxidase B inhibitor intake. No impact of the number of previous oral levodopa intakes was found. Rasagiline and safinamide did not essentially differ in terms of inhibition of monoamine oxidase B despite their different pharmacology regarding reversibility of monoamine oxidase B inhibition. In view of the observed, considerable heterogeneity of enzyme activities, we suggest to determine activities of monoamine oxidase A and B to reduce the risk for tyramine-induced hypertension and the serotonergic syndrome during chronic therapy with rasagiline or safinamide.

Proposed structural basis of interaction of piperine and related compounds with monoamine oxidases.

PubMed

Rahman, Taufiq; Rahmatullah, Mohammed

2010-01-15

Several studies have revealed piperine and a few related compounds as potent inhibitors of monoamine oxidases without delineating the underlying mechanism. Using in silico modelling, we propose a structural basis of such activity by showing that these compounds can successfully dock into the inhibitor binding pockets of human monoamine oxidase isoforms with predicted affinities comparable to some known inhibitors. The results therefore suggest that piperine can be a promising lead for developing novel monoamine oxidase inhibitors. Copyright 2009 Elsevier Ltd. All rights reserved.

Design, synthesis and biological evaluation of novel xanthine oxidase inhibitors bearing a 2-arylbenzo[b]furan scaffold.

PubMed

Tang, Hong-Jin; Li, Wei; Zhou, Mei; Peng, Li-Ying; Wang, Jin-Xin; Li, Jia-Huang; Chen, Jun

2018-05-10

Xanthine oxidase, which catalyzes the oxidative reaction of hypoxanthine and xanthine into uric acid, is a key enzyme to the pathogenesis of hyperuricemia and gout. In this study, for the purpose of discovering novel xanthine oxidase (XO) inhibitors, a series of 2-arylbenzo[b]furan derivatives (3a-3d, 4a-4o and 6a-6d) were designed and synthesized. All these compounds were evaluated their xanthine oxidase inhibitory and antioxidant activities by using in vitro enzymatic assay and cellular model. The results showed that a majority of the designed compounds exhibited potent xanthine oxidase inhibitory effects and antioxidant activities, and compound 4a emerged as the most potent xanthine oxidase inhibitor (IC 50  = 4.45 μM). Steady-state kinetic measurements of the inhibitor 4a with the bovine milk xanthine oxidase indicated a mixed type inhibition with 3.52 μM K i and 13.14 μM K is , respectively. The structure-activity relationship analyses have also been presented. Compound 4a exhibited the potent hypouricemic effect in the potassium oxonate-induced hyperuricemic mice model. A molecular docking study of compound 4a was performed to gain an insight into its binding mode with xanthine oxidase. These results highlight the identification of a new class of xanthine oxidase inhibitors that have potential to be more efficacious in treatment of gout. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Screening, separation, and evaluation of xanthine oxidase inhibitors from Paeonia lactiflora using chromatography combined with a multi-mode microplate reader.

PubMed

Wang, Jing; Shi, Dongfang; Zheng, Meizhu; Ma, Bing; Cui, Jing; Liu, Chunming; Liu, Chengyu

2017-11-01

Natural products have become one of the most important resources for discovering novel xanthine oxidase inhibitors, which are commonly employed in the treatment of hyperuricemia and gout. However, to date, few reports exist regarding the use of monoterpene glycosides as xanthine oxidase inhibitors. Thus, we herein report the use of ultrafiltration coupled with liquid chromatography in the screening of monoterpene glycoside xanthine oxidase inhibitors from the extract of Paeonia lactiflora (P. lactiflora), and both high-performance counter-current chromatography and medium-pressure liquid chromatography were employed to separate the main constituents. Furthermore, the xanthine oxidase inhibitory activities and the mechanisms of inhibition of the isolated compounds were evaluated using a multi-mode microplate reader by Molecular Devices. As a result, three monoterpene glycosides were separated by combined high-performance counter-current chromatography and medium-pressure liquid chromatography in purities of 90.4, 98.0, and 86.3%, as determined by liquid chromatography. These three compounds were identified as albiflorin, paeoniflorin, and 1-O-β-ᴅ-glucopyranosyl-8-O-benzoylpaeonisuffrone by electrospray ionization tandem mass spectrometry, and albiflorin and paeoniflorin were screened as potential xanthine oxidase inhibitors by ultrafiltration with liquid chromatography. The evaluation results of xanthine oxidase inhibitory activity corresponded with the screening results, as only albiflorin and paeoniflorin exhibited xanthine oxidase inhibitory activity. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

An updated patent review: xanthine oxidase inhibitors for the treatment of hyperuricemia and gout (2011-2015).

PubMed

Ojha, Ritu; Singh, Jagjeet; Ojha, Anu; Singh, Harbinder; Sharma, Sahil; Nepali, Kunal

2017-03-01

Xanthine oxidase (XO) is a versatile molybdoflavoprotein, widely distributed, occurring in milk, kidney, lung, heart, and vascular endothelium. Catalysis by XO to produce uric acid and reactive oxygen species leads to many diseases. Anti hyperuricemic therapy by xanthine oxidase inhibitors has been mainly employed for the treatment of gout. Area covered: This review covers the patent literature (2011-2015) and also presents the interesting strategies/rational approaches employed for the design of xanthine oxidase inhibitors reported recently. Expert opinion: Recent literature indicates that various non purine scaffolds have been extensively investigated for xanthine oxidase inhibition. The significant potential endowed by heteroaryl based compounds, in particularly fused heterocycles clearly highlights their clinical promise and the need for detailed investigation. Studies by various research groups have also revealed that the flavone framework is open for isosteric replacements and structural modifications for yielding potent non purine xanthine oxidase inhibitors. In addition, various plant extracts recently reported to possess significant xanthine oxidase inhibitory potential presents enough promise to initiate a screening program for the identification of other plant extracts and phytoconstituents possessing inhibitory potential towards the enzyme.

Metabolism of 2-phenylethylamine and phenylacetaldehyde by precision-cut guinea pig fresh liver slices.

PubMed

Panoutsopoulos, Georgios I; Kouretas, Demetrios; Gounaris, Elias G; Beedham, Christine

2004-01-01

2-Phenylethylamine is an endogenous constituent of human brain and is implicated in cerebral transmission. It is also found in certain foodstuffs and may cause toxic side-effects in susceptible individuals. Metabolism of 2-phenylethylamine to phenylacetaldehyde is catalyzed by monoamine oxidase and the oxidation of the reactive aldehyde to its acid derivative is catalyzed mainly by aldehyde dehydrogenase and perhaps aldehyde oxidase, with xanthine oxidase having minimal transformation. The present investigation examines the metabolism of 2-phenylethylamine to phenylacetaldehyde in liver slices and compares the relative contribution of aldehyde oxidase, xanthine oxidase and aldehyde dehydrogenase activity in the oxidation of phenylacetaldehyde with precision-cut fresh liver slices in the presence/absence of specific inhibitors of each enzyme. In liver slices, phenylacetaldehyde was rapidly converted to phenylacetic acid. Phenylacetic acid was the main metabolite of 2-phenylethylamine, via the intermediate phenylacetaldehyde. Phenylacetic acid formation was completely inhibited by disulfiram (specific inhibitor of aldehyde dehydrogenase), whereas isovanillin (specific inhibitor of aldehyde oxidase) inhibited acid formation to a lesser extent and allopurinol (specific inhibitor of xanthine oxidase) had little or no effect. Therefore, in liver slices, phenylacetaldehyde is rapidly oxidized by aldehyde dehydrogenase and aldehyde oxidase with little or no contribution from xanthine oxidase.

Design, synthesis and molecular modeling of aloe-emodin derivatives as potent xanthine oxidase inhibitors.

PubMed

Shi, Da-Hua; Huang, Wei; Li, Chao; Liu, Yu-Wei; Wang, Shi-Fan

2014-03-21

A series of aloe-emodin derivatives were synthesized and evaluated as xanthine oxidase inhibitors. Among them, four aloe-emodin derivatives showed significant inhibitory activities against xanthine oxidase. The compound 4,5-dihydroxy-9,10-dioxo-9,10-dihydroanthracene-2-carbaldehyde (A1) possessed the best xanthine oxidase inhibitory activity with IC50 of 2.79 μM. Lineweaver-Burk plot analysis revealed that A1 acted as a mixed-type inhibitor for xanthine oxidase. The docking study revealed that the molecule A1 had strong interactions with the active site of xanthine oxidase and this result was in agreement with kinetic study. Consequently, compound A1 is a new-type candidate for further development for the treatment of gout. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Current status of NADPH oxidase research in cardiovascular pharmacology.

PubMed

Rodiño-Janeiro, Bruno K; Paradela-Dobarro, Beatriz; Castiñeiras-Landeira, María Isabel; Raposeiras-Roubín, Sergio; González-Juanatey, José R; Alvarez, Ezequiel

2013-01-01

The implications of reactive oxygen species in cardiovascular disease have been known for some decades. Rationally, therapeutic antioxidant strategies combating oxidative stress have been developed, but the results of clinical trials have not been as good as expected. Therefore, to move forward in the design of new therapeutic strategies for cardiovascular disease based on prevention of production of reactive oxygen species, steps must be taken on two fronts, ie, comprehension of reduction-oxidation signaling pathways and the pathophysiologic roles of reactive oxygen species, and development of new, less toxic, and more selective nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitors, to clarify both the role of each NADPH oxidase isoform and their utility in clinical practice. In this review, we analyze the value of NADPH oxidase as a therapeutic target for cardiovascular disease and the old and new pharmacologic agents or strategies to prevent NADPH oxidase activity. Some inhibitors and different direct or indirect approaches are available. Regarding direct NADPH oxidase inhibition, the specificity of NADPH oxidase is the focus of current investigations, whereas the chemical structure-activity relationship studies of known inhibitors have provided pharmacophore models with which to search for new molecules. From a general point of view, small-molecule inhibitors are preferred because of their hydrosolubility and oral bioavailability. However, other possibilities are not closed, with peptide inhibitors or monoclonal antibodies against NADPH oxidase isoforms continuing to be under investigation as well as the ongoing search for naturally occurring compounds. Likewise, some different approaches include inhibition of assembly of the NADPH oxidase complex, subcellular translocation, post-transductional modifications, calcium entry/release, electron transfer, and genetic expression. High-throughput screens for any of these activities could provide new inhibitors. All this knowledge and the research presently underway will likely result in development of new drugs for inhibition of NADPH oxidase and application of therapeutic approaches based on their action, for the treatment of cardiovascular disease in the next few years.

Current status of NADPH oxidase research in cardiovascular pharmacology

PubMed Central

Rodiño-Janeiro, Bruno K; Paradela-Dobarro, Beatriz; Castiñeiras-Landeira, María Isabel; Raposeiras-Roubín, Sergio; González-Juanatey, José R; Álvarez, Ezequiel

2013-01-01

The implications of reactive oxygen species in cardiovascular disease have been known for some decades. Rationally, therapeutic antioxidant strategies combating oxidative stress have been developed, but the results of clinical trials have not been as good as expected. Therefore, to move forward in the design of new therapeutic strategies for cardiovascular disease based on prevention of production of reactive oxygen species, steps must be taken on two fronts, ie, comprehension of reduction-oxidation signaling pathways and the pathophysiologic roles of reactive oxygen species, and development of new, less toxic, and more selective nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitors, to clarify both the role of each NADPH oxidase isoform and their utility in clinical practice. In this review, we analyze the value of NADPH oxidase as a therapeutic target for cardiovascular disease and the old and new pharmacologic agents or strategies to prevent NADPH oxidase activity. Some inhibitors and different direct or indirect approaches are available. Regarding direct NADPH oxidase inhibition, the specificity of NADPH oxidase is the focus of current investigations, whereas the chemical structure-activity relationship studies of known inhibitors have provided pharmacophore models with which to search for new molecules. From a general point of view, small-molecule inhibitors are preferred because of their hydrosolubility and oral bioavailability. However, other possibilities are not closed, with peptide inhibitors or monoclonal antibodies against NADPH oxidase isoforms continuing to be under investigation as well as the ongoing search for naturally occurring compounds. Likewise, some different approaches include inhibition of assembly of the NADPH oxidase complex, subcellular translocation, post-transductional modifications, calcium entry/release, electron transfer, and genetic expression. High-throughput screens for any of these activities could provide new inhibitors. All this knowledge and the research presently underway will likely result in development of new drugs for inhibition of NADPH oxidase and application of therapeutic approaches based on their action, for the treatment of cardiovascular disease in the next few years. PMID:23983473

MAOIs and transdermal delivery.

PubMed

Vandenberg, Chad M

2012-09-01

Although not currently considered a first-line treatment for depression due to safety and tolerability concerns, MAOIs are effective antidepressants, particularly for atypical or treatment-resistant depression. FDA-approved oral MAOIs inhibit both MAO-A and MAO-B; inhibition of MAO-A in the brain is required for an antidepressant effect, but inhibition in the intestinal tract can allow excessive absorption of tyramine, which can lead to hypertensive crisis. A transdermal formulation of selegiline delivers the medication directly into the circulatory system, bypassing the first-pass metabolism of the GI system and substantially reducing the risk for tyramine-related adverse events. The skin patch allows for a lower dose of the drug to achieve an antidepressant effect, maintains a steady dose of the medication over 24 hours, and avoids the need for dietary restrictions at the minimum effective dose of 6 mg/24 hours. MAOIs are useful treatment options for patients who have not responded to first-line treatments, and understanding their mechanism of action can help clinicians to accurately and safely prescribe these medications. © Copyright 2012 Physicians Postgraduate Press, Inc.

(/sup 11/C)clorgyline and (/sup 11/C)-L-deprenyl and their use in measuring functional monoamine oxidase activity in the brain using positron emission tomography

DOEpatents

Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.

1986-04-17

This invention involves a new strategy for imaging the activity of the enzyme monoamine oxidase in the living body by using /sup 11/C-labeled enzyme inhibitors which bind irreversibly to an enzyme as a result of catalysis. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography. 2 figs.

Metabolism of 2-phenylethylamine to phenylacetic acid, via the intermediate phenylacetaldehyde, by freshly prepared and cryopreserved guinea pig liver slices.

PubMed

Panoutsopoulos, Georgios I

2004-01-01

2-Phenylethylamine is an endogenous amine, which acts as a neuromodulator of dopaminergic responses. Exogenous 2-phenylethylamine is found in certain foodstuffs and may cause toxic side-effects in susceptible individuals. The present investigation examined the metabolism of 2-phenylethylamine to phenylacetic acid, via phenylacetaldehyde, in freshly prepared and cryopreserved liver slices. Additionally, it compared the relative contribution of aldehyde oxidase, xanthine oxidase and aldehyde dehydrogenase by using specific inhibitors for each oxidizing enzyme. In freshly prepared and cryopreserved liver slices, phenylacetic acid was the main metabolite of 2-phenylethalamine. In freshly prepared liver slices, phenylacetic acid was completely inhibited by disulfiram (inhibitor of aldehyde dehydrogenase), whereas isovanillin (inhibitor of aldehyde oxidase) inhibited acid formation to a lesser extent and allopurinol (inhibitor of xanthine oxidase) had no effect. In cryopreserved liver slices, isovanillin inhibited phenylacetic acid by 85%, whereas disulfiram inhibited acid formation to a lesser extent and allopurinol had no effect. In liver slices, 2-phenylethylamine is rapidly oxidized to phenylacetic acid, via phenylacetaldehyde, by aldehyde dehydrogenase and aldehyde oxidase with no contribution from xanthine oxidase.

Targeting NADPH oxidases in vascular pharmacology

PubMed Central

Schramm, Agata; Matusik, Paweł; Osmenda, Grzegorz; Guzik, Tomasz J

2012-01-01

Oxidative stress is a molecular dysregulation in reactive oxygen species (ROS) metabolism, which plays a key role in the pathogenesis of atherosclerosis, vascular inflammation and endothelial dysfunction. It is characterized by a loss of nitric oxide (NO) bioavailability. Large clinical trials such as HOPE and HPS have not shown a clinical benefit of antioxidant vitamin C or vitamin E treatment, putting into question the role of oxidative stress in cardiovascular disease. A change in the understanding of the molecular nature of oxidative stress has been driven by the results of these trials. Oxidative stress is no longer perceived as a simple imbalance between the production and scavenging of ROS, but as a dysfunction of enzymes involved in ROS production. NADPH oxidases are at the center of these events, underlying the dysfunction of other oxidases including eNOS uncoupling, xanthine oxidase and mitochondrial dysfunction. Thus NADPH oxidases are important therapeutic targets. Indeed, HMG-CoA reductase inhibitors (statins) as well as drugs interfering with the renin-angiotensin-aldosterone system inhibit NADPH oxidase activation and expression. Angiotensin-converting enzyme (ACE) inhibitors, AT1 receptor antagonists (sartans) and aliskiren, as well as spironolactone or eplerenone, have been discussed. Molecular aspects of NADPH oxidase regulation must be considered, while thinking about novel pharmacological targeting of this family of enzymes consisting of several homologs Nox1, Nox2, Nox3, Nox4 and Nox5 in humans. In order to properly design trials of antioxidant therapies, we must develop reliable techniques for the assessment of local and systemic oxidative stress. Classical antioxidants could be combined with novel oxidase inhibitors. In this review, we discuss NADPH oxidase inhibitors such as VAS2870, VAS3947, GK-136901, S17834 or plumbagin. Therefore, our efforts must focus on generating small molecular weight inhibitors of NADPH oxidases, allowing the selective inhibition of dysfunctional NADPH oxidase homologs. This appears to be the most reasonable approach, potentially much more efficient than non-selective scavenging of all ROS by the administration of antioxidants. PMID:22405985

Positron emitter labeled enzyme inhibitors

DOEpatents

Fowler, Joanna S.; MacGregor, Robert R.; Wolf, Alfred P.; Langstrom, Bengt

1990-01-01

This invention involves a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide inactivators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography.

Effects of Long-Term Ayahuasca Administration on Memory and Anxiety in Rats

PubMed Central

Favaro, Vanessa Manchim; Yonamine, Maurício; Soares, Juliana Carlota Kramer; Oliveira, Maria Gabriela Menezes

2015-01-01

Ayahuasca is a hallucinogenic beverage that combines the action of the 5-HT2A/2C agonist N,N-dimethyltryptamine (DMT) from Psychotria viridis with the monoamine oxidase inhibitors (MAOIs) induced by beta-carbonyls from Banisteriopsis caapi. Previous investigations have highlighted the involvement of ayahuasca with the activation of brain regions known to be involved with episodic memory, contextual associations and emotional processing after ayahuasca ingestion. Moreover long term users show better performance in neuropsychological tests when tested in off-drug condition. This study evaluated the effects of long-term administration of ayahuasca on Morris water maze (MWM), fear conditioning and elevated plus maze (EPM) performance in rats. Behavior tests started 48h after the end of treatment. Freeze-dried ayahuasca doses of 120, 240 and 480 mg/kg were used, with water as the control. Long-term administration consisted of a daily oral dose for 30 days by gavage. The behavioral data indicated that long-term ayahuasca administration did not affect the performance of animals in MWM and EPM tasks. However the dose of 120 mg/kg increased the contextual conditioned fear response for both background and foreground fear conditioning. The tone conditioned response was not affected after long-term administration. In addition, the increase in the contextual fear response was maintained during the repeated sessions several weeks after training. Taken together, these data showed that long-term ayahuasca administration in rats can interfere with the contextual association of emotional events, which is in agreement with the fact that the beverage activates brain areas related to these processes. PMID:26716991

Effects of Long-Term Ayahuasca Administration on Memory and Anxiety in Rats.

PubMed

Favaro, Vanessa Manchim; Yonamine, Maurício; Soares, Juliana Carlota Kramer; Oliveira, Maria Gabriela Menezes

2015-01-01

Ayahuasca is a hallucinogenic beverage that combines the action of the 5-HT2A/2C agonist N,N-dimethyltryptamine (DMT) from Psychotria viridis with the monoamine oxidase inhibitors (MAOIs) induced by beta-carbonyls from Banisteriopsis caapi. Previous investigations have highlighted the involvement of ayahuasca with the activation of brain regions known to be involved with episodic memory, contextual associations and emotional processing after ayahuasca ingestion. Moreover long term users show better performance in neuropsychological tests when tested in off-drug condition. This study evaluated the effects of long-term administration of ayahuasca on Morris water maze (MWM), fear conditioning and elevated plus maze (EPM) performance in rats. Behavior tests started 48h after the end of treatment. Freeze-dried ayahuasca doses of 120, 240 and 480 mg/kg were used, with water as the control. Long-term administration consisted of a daily oral dose for 30 days by gavage. The behavioral data indicated that long-term ayahuasca administration did not affect the performance of animals in MWM and EPM tasks. However the dose of 120 mg/kg increased the contextual conditioned fear response for both background and foreground fear conditioning. The tone conditioned response was not affected after long-term administration. In addition, the increase in the contextual fear response was maintained during the repeated sessions several weeks after training. Taken together, these data showed that long-term ayahuasca administration in rats can interfere with the contextual association of emotional events, which is in agreement with the fact that the beverage activates brain areas related to these processes.

Hallucinogens and dissociative agents naturally growing in the United States.

PubMed

Halpern, John H

2004-05-01

It is usually believed that drugs of abuse are smuggled into the United States or are clandestinely produced for illicit distribution. Less well known is that many hallucinogens and dissociative agents can be obtained from plants and fungi growing wild or in gardens. Some of these botanical sources can be located throughout the United States; others have a more narrow distribution. This article reviews plants containing N,N-dimethyltryptamine, reversible type A monoamine oxidase inhibitors (MAOI), lysergic acid amide, the anticholinergic drugs atropine and scopolamine, or the diterpene salvinorin-A (Salvia divinorum). Also reviewed are mescaline-containing cacti, psilocybin/psilocin-containing mushrooms, and the Amanita muscaria and Amanita pantherina mushrooms that contain muscimol and ibotenic acid. Dangerous misidentification is most common with the mushrooms, but even a novice forager can quickly learn how to properly identify and prepare for ingestion many of these plants. Moreover, through the ever-expanding dissemination of information via the Internet, this knowledge is being obtained and acted upon by more and more individuals. This general overview includes information on the geographical range, drug content, preparation, intoxication, and the special health risks associated with some of these plants. Information is also offered on the unique issue of when bona fide religions use such plants as sacraments in the United States. In addition to the Native American Church's (NAC) longstanding right to peyote, two religions of Brazilian origin, the Santo Daime and the Uniao do Vegetal (UDV), are seeking legal protection in the United States for their use of sacramental dimethyltryptamine-containing "ayahuasca."

[Antidepressant and tolerance: Determinants and management of major side effects].

PubMed

David, D J; Gourion, D

2016-12-01

Antidepressant therapy aims to reach remission of depressive symptoms while reducing the complications and risks of relapse. Even though they have proven their efficacy, it takes several weeks for antidepressants to demonstrate full effectiveness, and adverse effects occur more quickly or (quicker) which can be a source of poor compliance. This latest aspect often leads to dose reduction and/or change of molecule that have the effect of delaying remission. This review attempts to present, from the pharmacological properties of the major classes of antidepressants (monoamine oxidase inhibitor [MAOI], tricyclic antidepressants [TCA], selective serotonin reuptake inhibitor [SSRI] and serotonin and noradrenaline reuptake inhibitor [SNRI]), to the pharmacological mechanisms involved in adverse effects by focusing on sexual dysfunction, nausea/vomiting, and weight changes and sleep disruption. If the activation of dopamine D 1/2  or norepinephrine receptors through the autonomic nervous system controls and facilitates sexual desire, increasing serotoninergic transmission through 5-HT 1B/2A/2C receptors activation inhibits this process. The pharmacological properties of drugs inducing nausea/vomiting activate opiate receptors μ, increase dopaminergic and serotoninergic transmission activating the dopamine D 2  and serotonin 5-HT 3  receptors, respectively. Among the causes responsible for weight gain under antidepressant therapy, monoamine neurotransmission still plays an important role. The blockade of serotonin 5-HT 2C or histamine H 1  receptors is directly responsible for weight gain. Finally, the activation of 5-HT 1A/1B/3/7 serotoninergique receptors modulates wakefulness, raid eyes movement or sleep duration. In conclusion, if antidepressant activity of SERT or MAO inhibitors is an indirect consequence of postsynaptic 5-HT, DA, NA receptor activation, it is also responsible for side effects, causes of poor compliance and hence therapeutic failures. Finally, we need to take into account the key role of the nocebo effect in the occurrence of adverse effects. The next generation of antidepressant would aim to have a rapid efficacy in patients unresponsive or resistant to drugs currently available while improving certain effects of tolerance through an optimization of their psychopharmacological properties leading to a reduction of their side effects. Copyright © 2016 L’Encéphale, Paris. Published by Elsevier Masson SAS. All rights reserved.

Evolution of NADPH Oxidase Inhibitors: Selectivity and Mechanisms for Target Engagement.

PubMed

Altenhöfer, Sebastian; Radermacher, Kim A; Kleikers, Pamela W M; Wingler, Kirstin; Schmidt, Harald H H W

2015-08-10

Oxidative stress, an excess of reactive oxygen species (ROS) production versus consumption, may be involved in the pathogenesis of different diseases. The only known enzymes solely dedicated to ROS generation are nicotinamide adenine dinucleotide phosphate (NADPH) oxidases with their catalytic subunits (NOX). After the clinical failure of most antioxidant trials, NOX inhibitors are the most promising therapeutic option for diseases associated with oxidative stress. Historical NADPH oxidase inhibitors, apocynin and diphenylene iodonium, are un-specific and not isoform selective. Novel NOX inhibitors stemming from rational drug discovery approaches, for example, GKT137831, ML171, and VAS2870, show improved specificity for NADPH oxidases and moderate NOX isoform selectivity. Along with NOX2 docking sequence (NOX2ds)-tat, a peptide-based inhibitor, the use of these novel small molecules in animal models has provided preliminary in vivo evidence for a pathophysiological role of specific NOX isoforms. Here, we discuss whether novel NOX inhibitors enable reliable validation of NOX isoforms' pathological roles and whether this knowledge supports translation into pharmacological applications. Modern NOX inhibitors have increased the evidence for pathophysiological roles of NADPH oxidases. However, in comparison to knockout mouse models, NOX inhibitors have limited isoform selectivity. Thus, their use does not enable clear statements on the involvement of individual NOX isoforms in a given disease. The development of isoform-selective NOX inhibitors and biologicals will enable reliable validation of specific NOX isoforms in disease models other than the mouse. Finally, GKT137831, the first NOX inhibitor in clinical development, is poised to provide proof of principle for the clinical potential of NOX inhibition.

Positron emitter labeled enzyme inhibitors

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

Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.

This invention involves a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide inactivators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline andmore » L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography.« less

Positron emitter labeled enzyme inhibitors

DOEpatents

Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.

1987-05-22

This invention involved a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide in activators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgyline and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography. 2 figs.

Positron emitter labeled enzyme inhibitors

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

Fowler, J.S.; MacGregor, R.R.; Wolf, A.P.

This invention involved a new strategy for imaging and mapping enzyme activity in the living human and animal body using positron emitter-labeled suicide enzyme inactivators or inhibitors which become covalently bound to the enzyme as a result of enzymatic catalysis. Two such suicide in activators for monoamine oxidase have been labeled with carbon-11 and used to map the enzyme subtypes in the living human and animal body using PET. By using positron emission tomography to image the distribution of radioactivity produced by the body penetrating radiation emitted by carbon-11, a map of functionally active monoamine oxidase activity is obtained. Clorgylinemore » and L-deprenyl are suicide enzyme inhibitors and irreversibly inhibit monoamine oxidase. When these inhibitors are labeled with carbon-11 they provide selective probes for monoamine oxidase localization and reactivity in vivo using positron emission tomography. 2 figs.« less

Hydroxychavicol: a potent xanthine oxidase inhibitor obtained from the leaves of betel, Piper betle.

PubMed

Murata, Kazuya; Nakao, Kikuyo; Hirata, Noriko; Namba, Kensuke; Nomi, Takao; Kitamura, Yoshihisa; Moriyama, Kenzo; Shintani, Takahiro; Iinuma, Munekazu; Matsuda, Hideaki

2009-07-01

The screening of Piperaceous plants for xanthine oxidase inhibitory activity revealed that the extract of the leaves of Piper betle possesses potent activity. Activity-guided purification led us to obtain hydroxychavicol as an active principle. Hydroxychavicol is a more potent xanthine oxidase inhibitor than allopurinol, which is clinically used for the treatment of hyperuricemia.

Recent advances in Parkinson's disease therapy: use of monoamine oxidase inhibitors.

PubMed

Henchcliffe, Claire; Schumacher, H Christian; Burgut, F Tuna

2005-11-01

Monoamine oxidase inhibitors inhibit dopamine metabolism and are therefore effective in treating Parkinson's disease, a condition associated with progressive striatal dopamine deficiency secondary to degeneration of dopaminergic neurons in the substantia nigra. Selegiline is currently the most widely used monoamine oxidase-B inhibitor for Parkinson's disease, but has a low and variable bioavailability, and is metabolized to L-methamphetamine and L-amphetamine that carry a risk for potential neurotoxicity. There are two new approaches that circumvent these potential disadvantages. First, selegiline orally disintegrating tablets provide a novel delivery form of selegiline, avoiding first pass metabolism by rapid absorption through the oral mucosa, thus leading to significantly lower plasma concentrations of L-metamphetamine and L-amphetamine. Selegiline orally disintegrating tablets prove to be clinically effective and safe in patients with moderately advanced Parkinson's disease. Second, rasagiline is a new monoamine oxidase inhibitor, without known neurotoxic metabolites. In large clinical trials, rasagiline proves effective as monotherapy in early Parkinson's disease, as well as adjunctive therapy to levodopa in advanced disease. Clinical data suggest, in addition, a disease-modifying effect of rasagiline that may correlate with neuroprotective activity of monoamine oxidase-B inhibitors in animal models of Parkinson's disease.

Contribution of aldehyde oxidizing enzymes on the metabolism of 3,4-dimethoxy-2-phenylethylamine to 3,4-dimethoxyphenylacetic acid by guinea pig liver slices.

PubMed

Panoutsopoulos, Georgios I

2006-01-01

3,4-Dimethoxy-2-phenylethylamine is catalyzed to its aldehyde derivative by monoamine oxidase B, but the subsequent oxidation into the corresponding acid has not yet been studied. Oxidation of aromatic aldehydes is catalyzed mainly by aldehyde dehydrogenase and aldehyde oxidase. The present study examines the metabolism of 3,4-dimethoxy-2-phenylethylamine in vitro and in freshly prepared and cryopreserved guinea pig liver slices and the relative contribution of different aldehyde-oxidizing enzymes was estimated by pharmacological means. 3,4-Dimethoxy-2- phenylethylamine was converted into the corresponding aldehyde when incubated with monoamine oxidase and further oxidized into the acid when incubated with both, monoamine oxidase and aldehyde oxidase. In freshly prepared and cryopreserved liver slices, 3,4-dimethoxyphenylacetic acid was the main metabolite of 3,4-dimethoxy-2- phenylethylamine. 3,4-Dimethoxyphenylacetic acid formation was inhibited by 85% from disulfiram (aldehyde dehydrogenase inhibitor) and by 75-80% from isovanillin (aldehyde oxidase inhibitor), whereas allopurinol (xanthine oxidase inhibitor) inhibited acid formation by only 25-30%. 3,4- Dimethoxy-2-phenylethylamine is oxidized mainly to its acid, via 3,4-dimethoxyphenylacetaldehyde, by aldehyde dehydrogenase and aldehyde oxidase with a lower contribution from xanthine oxidase.

Selective Rac1 inhibition protects renal tubular epithelial cells from oxalate-induced NADPH oxidase-mediated oxidative cell injury

PubMed Central

Thamilselvan, Vijayalakshmi; Menon, Mani

2013-01-01

Oxalate-induced oxidative cell injury is one of the major mechanisms implicated in calcium oxalate nucleation, aggregation and growth of kidney stones. We previously demonstrated that oxalate-induced NADPH oxidase-derived free radicals play a significant role in renal injury. Since NADPH oxidase activation requires several regulatory proteins, the primary goal of this study was to characterize the role of Rac GTPase in oxalate-induced NADPH oxidase-mediated oxidative injury in renal epithelial cells. Our results show that oxalate significantly increased membrane translocation of Rac1 and NADPH oxidase activity of renal epithelial cells in a time-dependent manner. We found that NSC23766, a selective inhibitor of Rac1, blocked oxalate-induced membrane translocation of Rac1 and NADPH oxidase activity. In the absence of Rac1 inhibitor, oxalate exposure significantly increased hydrogen peroxide formation and LDH release in renal epithelial cells. In contrast, Rac1 inhibitor pretreatment, significantly decreased oxalate-induced hydrogen peroxide production and LDH release. Furthermore, PKC α and δ inhibitor, oxalate exposure did not increase Rac1 protein translocation, suggesting that PKC resides upstream from Rac1 in the pathway that regulates NADPH oxidase. In conclusion, our data demonstrate for the first time that Rac1-dependent activation of NADPH oxidase might be a crucial mechanism responsible for oxalate-induced oxidative renal cell injury. These findings suggest that Rac1 signaling plays a key role in oxalate-induced renal injury, and may serve as a potential therapeutic target to prevent calcium oxalate crystal deposition in stone formers and reduce recurrence. PMID:21814770

Regular Consumption of Sauerkraut and Its Effect on Human Health: A Bibliometric Analysis

PubMed Central

Ostermann, Thomas; Boehm, Katja; Molsberger, Friedrich

2014-01-01

Background: Sauerkraut is one of the most common and oldest forms of preserving cabbage and can be traced back as a food source to the 4th century BC. It contains a large quantity of lactic acid and tyramines, as well as vitamins and minerals, and has few calories. Objective: We aimed to provide an overview regarding the evidence of the effects of sauerkraut on human health by means of a bibliometric analysis. Methodology: Electronic databases (Medline, AMED, CamBase, CamQuest, the Cochrane Central Register of Controlled Trials, the Database of Abstracts of Reviews of Effects, the Cochrane Database of Systematic Reviews, EMBASE, the Karger-Publisher and the Thieme-Publisher databases) were searched from their inception until September 2012. Results: The search revealed 139 publications ranging over a 90-year period from 1921 to 2012. The majority of publications originated from Europe (48.6%), followed by the United States (30.7%) and Asia (10%). More than half of the research (56.8%) focused on food analysis, and 23.7% evaluated the impact of sauerkraut on health, including risk factors or digestive well-being. Direct research in humans was almost constant over time at about 11.5%. The studies found that sauerkraut induced inflammation locally, but repeated intake may result in diarrhea. Some studies pointed out anticarcinogenic effects of sauerkraut, while others concentrated on the interaction with monoamine oxidase inhibitors (MAOIs). Discussion: Sauerkraut, one of the oldest traditional foods, has a variety of beneficial effects on human health. However, unwanted effects such as intolerance reactions must be considered when dealing with sauerkraut as a functional food. PMID:25568828

A rapid and simple method for the determination of psychoactive alkaloids by CE-UV: application to Peganum Harmala seed infusions.

PubMed

Tascón, Marcos; Benavente, Fernando; Vizioli, Nora M; Gagliardi, Leonardo G

2017-04-01

The β-carboline alkaloids of the harmala (HAlks) group are compounds widely spread in many natural sources, but found at relatively high levels in some specific plants like Peganum harmala (Syrian rue) or Banisteriopsis caapi. HAlks are a reversible Mono Amino Oxidase type A Inhibitor (MAOI) and, as a consequence, these plants or their extracts can be used to produce psychotropic effects when are combined with psychotropic drugs based on amino groups. Since the occurrence and the levels of the HAlks in natural sources are subject to significant variability, more widespread use is not clinical but recreational or ritual, for example B. caapi is a known part of the Ayahuasca ritual mixture. The lack of simple methods to control the variable levels of these compounds in natural sources restricts the possibilities to dose in strict quantities and, as a consequence, limits its use with pharmacological or clinical purposes. In this work, we present a fast, simple, and robust method of quantifying simultaneously the six HAlks more frequently found in plants, i.e., harmine, harmaline, harmol, harmalol, harmane, and norharmane, by capillary electrophoresis instruments equipped with the more common detector UV. The method is applied to analyze these HAlks in P. Harmala seeds infusion which is a frequent intake form for these HAlks. The method is validated in three different instruments in order to evaluate the transferability and to compare the performances between them. In this case, harmaline, harmine, and harmol were found in the infusion samples. Copyright © 2016 John Wiley & Sons, Ltd. Copyright © 2016 John Wiley & Sons, Ltd.

Soma, food of the immortals according to the Bower Manuscript (Kashmir, 6th century A.D.).

PubMed

Leonti, Marco; Casu, Laura

2014-08-08

Food is medicine and vice versa. In Hindu and Ayurvedic medicine, and among human cultures of the Indian subcontinent in general, the perception of the food-medicine continuum is especially well established. The preparation of the exhilarating, gold-coloured Soma, Amrita or Ambrosia, the elixir and food of the 'immortals'-the Hindu pantheon-by the ancient Indo-Aryans, is described in the Rigveda in poetic hymns. Different theories regarding the botanical identity of Soma circulate, but no pharmacologically and historically convincing theory exists to date. We intend to contribute to the botanical, chemical and pharmacological characterisation of Soma through an analysis of two historical Amrita recipes recorded in the Bower Manuscript. The recipes are referred therein as panaceas (clarified butter) and also as a medicine to treat nervous diseases (oil), while no exhilarating properties are mentioned. Notwithstanding this, we hypothesise, that these recipes are related to the ca. 1800 years older Rigvedic Soma. We suppose that the psychoactive Soma ingredient(s) are among the components, possibly in smaller proportions, of the Amrita recipes preserved in the Bower Manuscript. The Bower Manuscript is a medical treatise recorded in the 6th century A.D. in Sanskrit on birch bark leaves, probably by Buddhist monks, and unearthed towards the end of the 19th century in Chinese Turkestan. We analysed two Amrita recipes from the Bower Manuscript, which was translated by Rudolf Hoernle into English during the early 20th century. A database search with the updated Latin binomials of the herbal ingredients was used to gather quantitative phytochemical and pharmacological information. Together, both Amrita recipes contain around 100 herbal ingredients. Psychoactive alkaloid containing species still important in Ayurvedic, Chinese and Thai medicine and mentioned in the recipe for 'Amrita-Prâsa clarified butter' and 'Amrita Oil' are: Tinospora cordifolia (Amrita, Guduchi), three Sida spp., Mucuna pruriens, Nelumbo nucifera, Desmodium gangeticum, and Tabernaemontana divaricata. These species contain several notorious and potential psychoactive and psychedelic alkaloids, namely: tryptamines, 2-phenylethylamine, ephedrine, aporphines, ibogaine, and L-DOPA. Furthermore, protoberberine alkaloids, tetrahydro-β-carbolines, and tetrahydroisoquinolines with monoamine oxidase inhibitor (MAO-I) activity but also neurotoxic properties are reported. We propose that Soma was a combination of a protoberberine alkaloids containing Tinospora cordifolia juice with MAO-I properties mixed together with a tryptamine rich Desmodium gangeticum extract or a blending of Tinospora cordifolia with an ephedrine and phenylethylamine-rich Sida spp. extract. Tinospora cordifolia combined with Desmodium gangeticum might provide a psychedelic experience with visual effects, while a combination of Tinospora cordifolia with Sida spp. might lead to more euphoric and amphetamine-like experiences. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

Dual inhibitors of cholinesterases and monoamine oxidases for Alzheimer's disease.

PubMed

Knez, Damijan; Sova, Matej; Košak, Urban; Gobec, Stanislav

2017-05-01

Accumulating evidence indicates a solid relationship between several enzymes and Alzheimer's disease. Cholinesterases and monoamine oxidases are closely associated with the disease symptomatology and progression and have been tackled simultaneously using several multifunctional ligands. This design strategy offers great chances to alter the course of Alzheimer's disease, in addition to alleviation of the symptoms. More than 15 years of research has led to the identification of various dual cholinesterase/monoamine oxidase inhibitors, while some showing positive outcomes in clinical trials, thus giving rise to additional research efforts in the field. The aim of this review is to provide an update on the novel dual inhibitors identified recently and to shed light on their therapeutic potential.

The dual actions of Paederia scandens extract as a hypouricemic agent: xanthine oxidase inhibitory activity and uricosuric effect.

PubMed

Yan, Haiyan; Ma, Ying; Liu, Mei; Zhou, Lanlan

2008-09-01

Hyperuricemia is associated with a number of pathological conditions, such as gout. Lowering of elevated uric acid levels in the blood could be achieved by xanthine oxidase inhibitors and inhibitors of renal urate reabsorption. Some natural compounds isolated from herbs used in traditional Chinese medicine have been previously demonstrated to act as xanthine oxidase inhibitors. In the present investigation, Paederia scandens (Lour.) Merrill (Rubiaceae) extract (PSE; 4.5, 2.25, and 1.125 g/kg) orally for 14 days was demonstrated to possess in vivo potent hypouricemic activity in hyperuricemic rats pretreated with potassium oxonate. In addition, PSE was also demonstrated to be an inhibitor of xanthine oxidase. Lineweaver-Burk analysis of the enzyme kinetics indicated that the inhibition of PSE was of a mixed type. Using an oxonate-induced hyperuricemic rat model, PSE was indeed shown to exhibit uricosuric action in vivo, which could explain, at least in part, the observed hypouricemic effect of PSE in these rats. The potential application of this compound in the treatment of conditions associated with hyperuricemia is discussed.

NADPH oxidases as novel pharmacologic targets against influenza A virus infection.

PubMed

Vlahos, Ross; Selemidis, Stavros

2014-12-01

Influenza A viruses represent a major global health care challenge, with imminent pandemics, emerging antiviral resistance, and long lag times for vaccine development, raising a pressing need for novel pharmacologic strategies that ideally target the pathology irrespective of the infecting strain. Reactive oxygen species (ROS) pervade all facets of cell biology with both detrimental and protective properties. Indeed, there is compelling evidence that activation of the NADPH oxidase 2 (NOX2) isoform of the NADPH oxidase family of ROS-producing enzymes promotes lung oxidative stress, inflammation, injury, and dysfunction resulting from influenza A viruses of low to high pathogenicity, as well as impeding virus clearance. By contrast, the dual oxidase isoforms produce ROS that provide vital protective antiviral effects for the host. In this review, we propose that inhibitors of NOX2 are better alternatives than broad-spectrum antioxidant approaches for treatment of influenza pathologies, for which clinical efficacy may have been limited owing to poor bioavailability and inadvertent removal of beneficial ROS. Finally, we briefly describe the current suite of NADPH oxidase inhibitors and the molecular features of the NADPH oxidase enzymes that could be exploited by drug discovery for development of more specific and novel inhibitors to prevent or treat disease caused by influenza. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

Isolation and characterization of a monoamine oxidase B selective inhibitor from tobacco smoke.

PubMed

Khalil, Ashraf A; Davies, Bruce; Castagnoli, Neal

2006-05-15

It is well established that tobacco smokers have reduced levels of monoamine oxidase activities both in the brain and peripheral organs. Furthermore, extensive evidence suggests that smokers are less prone to develop Parkinson's disease. These facts, plus the observation that inhibition of monoamine oxidase B protects against the parkinsonian inducing effects of the nigrostriatal neurotoxin 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine, have prompted studies to identify monoamine oxidase inhibitors in the tobacco plant and tobacco cigarette smoke. Our previous efforts on cured tobacco leaf extracts have led to the characterization of 2,3,6-trimethyl-1,4-naphthoquinone, a non-selective monoamine oxidase inhibitor, and farnesylacetone, a selective monoamine oxidase B inhibitor. We now have extended these studies to tobacco smoke constituents. Fractionation of the smoke extracts has confirmed and extended the qualitative results of an earlier report [J. Korean Soc. Tob. Sci.1997, 19, 136] demonstrating the inhibitory activity of the terpene trans,trans-farnesol on rat brain MAO-B. In the present study, K(i) values for the inhibition of human, baboon, monkey, dog, rat, and mouse liver MAO-B have been determined. Noteworthy is the absence of inhibitory effects on human placental MAO-A and beef liver MAO-B. A limited structure-activity relationship study of analogs of trans,trans-farnesol is reported. Although the health hazards associated with the use of tobacco products preclude any therapeutic opportunities linked to smoking, these results suggest the possibility of identifying novel structures of compounds that could lead to the development of neuroprotective agents.

Phosphatidylinositol 3-Kinase Plays a Vital Role in Regulation of Rice Seed Vigor via Altering NADPH Oxidase Activity

PubMed Central

Liu, Jian; Zhou, Jun; Xing, Da

2012-01-01

Phosphatidylinositol 3-kinase (PI3K) has been reported to be important in normal plant growth and stress responses. In this study, it was verified that PI3K played a vital role in rice seed germination through regulating NADPH oxidase activity. Suppression of PI3K activity by inhibitors wortmannin or LY294002 could abate the reactive oxygen species (ROS) formation, which resulted in disturbance to the seed germination. And then, the signal cascades that PI3K promoted the ROS liberation was also evaluated. Diphenylene iodonium (DPI), an NADPH oxidase inhibitor, suppressed most of ROS generation in rice seed germination, which suggested that NADPH oxidase was the main source of ROS in this process. Pharmacological experiment and RT-PCR demonstrated that PI3K promoted the expression of Os rboh9. Moreover, functional analysis by native PAGE and the measurement of the 2, 3-bis-(2-methoxy-4-nitro-5-sulfophenyl)-2H-tetrazo-lium-5- carboxanilide (XTT) formazan concentration both showed that PI3K promoted the activity of NADPH oxidase. Furthermore, the western blot analysis of OsRac-1 demonstrated that the translocation of Rac-1 from cytoplasm to plasma membrane, which was known as a key factor in the assembly of NADPH oxidase, was suppressed by treatment with PI3K inhibitors, resulting in the decreased activity of NADPH oxidase. Taken together, these data favored the novel conclusion that PI3K regulated NADPH oxidase activity through modulating the recruitment of Rac-1 to plasma membrane and accelerated the process of rice seed germination. PMID:22448275

Design and synthesis of novel 2-(indol-5-yl)thiazole derivatives as xanthine oxidase inhibitors.

PubMed

Song, Jeong Uk; Choi, Sung Pil; Kim, Tae Hun; Jung, Cheol-Kyu; Lee, Joo-Youn; Jung, Sang-Hun; Kim, Geun Tae

2015-03-15

Xanthine oxidase (XO) inhibitors have been widely used for the treatment of gout. Indole rings are frequently used as active scaffold in designing inhibitors for enzymes. Herein, we describe the structure-activity relationship for novel xanthine oxidase inhibitors based on indole scaffold. A series of novel tri-substituted 2-(indol-5-yl)thiazole derivatives were synthesized, and their in vitro inhibitory activities against xanthine oxidase and in vivo efficacy lowering uric acid level in blood were measured. Among them, 2-(3-cyano-2-isopropylindol-5-yl)-4-methylthiazole-5-carboxylic acid exhibits the most potent XO inhibitory activity (IC50 value: 3.5nM) and the excellent plasma uric acid lowering activity. Study of structure activity relationship indicated that hydrophobic moiety (e.g., isopropyl) at 1-position and electron withdrawing group (e.g., CN) at 3-position of indole ring and small hydrophobic group (CH3) at 4-position of the thiazole ring enhanced the XO inhibitory activity. Hydrophobic substitution such as isopropyl at 1-position of the indole moiety without any substitution at 2-position has an essential role for enhancing bioavailability and therefore for high in vivo efficacy. Copyright © 2015 Elsevier Ltd. All rights reserved.

The hemibiotrophic cacao pathogen Moniliophthora perniciosa depends on a mitochondrial alternative oxidase for biotrophic development

USDA-ARS?s Scientific Manuscript database

The mitochondrial alternative oxidase (AOX) is a non-energy conserving ubiquinol oxidase found in most fungal genomes studied to date. With the development of fungicides containing cytochrome-dependent respiratory chain (CRC) inhibitors, a strong interest in studying AOX functions in phytopathogenic...

Discovery of a novel class of potent coumarin monoamine oxidase B inhibitors: development and biopharmacological profiling of 7-[(3-chlorobenzyl)oxy]-4-[(methylamino)methyl]-2H-chromen-2-one methanesulfonate (NW-1772) as a highly potent, selective, reversible, and orally active monoamine oxidase B inhibitor.

PubMed

Pisani, Leonardo; Muncipinto, Giovanni; Miscioscia, Teresa Fabiola; Nicolotti, Orazio; Leonetti, Francesco; Catto, Marco; Caccia, Carla; Salvati, Patricia; Soto-Otero, Ramon; Mendez-Alvarez, Estefania; Passeleu, Celine; Carotti, Angelo

2009-11-12

In an effort to discover novel selective monoamine oxidase (MAO) B inhibitors with favorable physicochemical and pharmacokinetic profiles, 7-[(m-halogeno)benzyloxy]coumarins bearing properly selected polar substituents at position 4 were designed, synthesized, and evaluated as MAO inhibitors. Several compounds with MAO-B inhibitory activity in the nanomolar range and excellent MAO-B selectivity (selectivity index SI > 400) were identified. Structure-affinity relationships and docking simulations provided valuable insights into the enzyme-inhibitor binding interactions at position 4, which has been poorly explored. Furthermore, computational and experimental studies led to the identification and biopharmacological characterization of 7-[(3-chlorobenzyl)oxy]-4-[(methylamino)methyl]-2H-chromen-2-one methanesulfonate 22b (NW-1772) as an in vitro and in vivo potent and selective MAO-B inhibitor, with rapid blood-brain barrier penetration, short-acting and reversible inhibitory activity, slight inhibition of selected cytochrome P450s, and low in vitro toxicity. On the basis of this preliminary preclinical profile, inhibitor 22b might be viewed as a promising clinical candidate for the treatment of neurodegenerative diseases.

Phytochemical investigation of some traditional chinese medicines and endophyte cultures.

PubMed

Tan, R X; Meng, J C; Hostettmann, K

2000-01-01

For many social and environmental reasons, over the last few decades, there has been an increase in chronic and life-threatening diseases including mycoses, hyperuricemia-related disorders and some mental illnesses such as depression, anxiety and Parkinson's disease. In order to fight these diseases, compounds acting on various biological targets, including enzymes such as xanthine oxidase or monoamine oxidase, have to be screened. The enzyme xanthine oxidase catalyses the oxidation of hypoxanthine to xanthine and then to uric acid, which plays a crucial role in hyperuricemiarelated disorders such as gout and renal stones. One of the therapeutic approaches to treat these diseases is the use of xanthine oxidase inhibitors that block the production of uric acid. Monoamine oxidases (E.C.1.4.3.4) A and B catalyse the oxidative deamination of monoamines in the central nervous system and peripheral tissues. Inhibitors of MAO A are clinically useful to treat anxiety and depression since they are expected to increase both noradrenalin and serotonin levels in the brain. On the other hand, inhibition of MAO B appears to be an effective approach for the prevention and adjunct treatment of Parkinson's disease. In traditional Chinese medical practice, many medicinal herbs have been used to treat chronic diseases such as fungal infections, hyperuricemia-based disorders and mental illnesses. This usage is indicative for the presumable presence of antifungal phytochemicals and inhibitors of xanthine and monoamine oxidases. Plants do not represent the only source for interesting natural products; some endophytes ('special' microorganisms living inside the healthy host plant) are also known to produce secondary metabolites of promising pharmaceutical and/or agricultural potential. The above observations prompted us to search for natural antifungal compounds and inhibitors of xanthine and monoamine oxidases in different Chinese plants and endophyte cultures. The active constituents isolated were mainly mono-, sesqui-, di-, and triterpenes, sterols, coumarins, flavonoids, phenylethanoids, stilbenoids, alkaloids and alcohols.

Structural insights into xenobiotic and inhibitor binding to human aldehyde oxidase.

PubMed

Coelho, Catarina; Foti, Alessandro; Hartmann, Tobias; Santos-Silva, Teresa; Leimkühler, Silke; Romão, Maria João

2015-10-01

Aldehyde oxidase (AOX) is a xanthine oxidase (XO)-related enzyme with emerging importance due to its role in the metabolism of drugs and xenobiotics. We report the first crystal structures of human AOX1, substrate free (2.6-Å resolution) and in complex with the substrate phthalazine and the inhibitor thioridazine (2.7-Å resolution). Analysis of the protein active site combined with steady-state kinetic studies highlight the unique features, including binding and substrate orientation at the active site, that characterize human AOX1 as an important drug-metabolizing enzyme. Structural analysis of the complex with the noncompetitive inhibitor thioridazine revealed a new, unexpected and fully occupied inhibitor-binding site that is structurally conserved among mammalian AOXs and XO. The new structural insights into the catalytic and inhibition mechanisms of human AOX that we now report will be of great value for the rational analysis of clinical drug interactions involving inhibition of AOX1 and for the prediction and design of AOX-stable putative drugs.

[Substrate-inhibitory analysis of monoamine oxidase from hepatopancreas of the octopus Bathypolypus arcticus].

PubMed

Basova, I N; Iagodina, O V

2012-01-01

Study of the substrate-inhibitory specificity of mitochondrial monoamine oxidase (MAO) of hepatopancreas of the octopus Bathypolypus arcticus revealed distinctive peculiarities of catalytic properties of this enzyme. The studied enzyme, on one hand, like the classic MAO of homoiothermal animals, is able to deaminate tyramine, serotonin, benzylamine, tryptamine, beta-phenylethylamine, while, on the other hand, deaminates histamine and does not deaminate putrescine--classic substrates of diamine oxidase (DAO). Results of the substrate-inhibitory analysis with use of chlorgiline and deprenyl are indirect proofs of the existence in the octopus hepatopancreas of one molecular MAO form. Semicarbazide and pyronine G turned out to be weak irreversible inhibitors, four derivatives of acridine--irreversible inhibitors of the intermediate effectiveness with respect to the octopus hepatopancreas MAO; specificity of action of inhibitors at deamination of different substrates was equal.

The NADPH oxidase inhibitor diphenyleneiodonium is also a potent inhibitor of cholinesterases and the internal Ca2+ pump

PubMed Central

Tazzeo, T; Worek, F; Janssen, LJ

2009-01-01

Background and purpose: Diphenyleneiodonium (DPI) is often used as an NADPH oxidase inhibitor, but is increasingly being found to have unrelated side effects. We investigated its effects on smooth muscle contractions and the related mechanisms. Experimental approach: We studied isometric contractions in smooth muscle strips from bovine trachea. Cholinesterase activity was measured using a spectrophotometric assay; internal Ca2+ pump activity was assessed by Ca2+ uptake into smooth muscle microsomes. Key results: Contractions to acetylcholine were markedly enhanced by DPI (10−4 M), whereas those to carbachol (CCh) were not, suggesting a possible inhibition of cholinesterase. DPI markedly suppressed contractions evoked by CCh, KCl and 5-HT, and also unmasked phasic activity in otherwise sustained responses. Direct biochemical assays confirmed that DPI was a potent inhibitor of acetylcholinesterase and butyrylcholinesterase (IC50∼8 × 10−6 M and 6 × 10−7 M, respectively), following a readily reversible, mixed non-competitive type of inhibition. The inhibitory effects of DPI on CCh contractions were not mimicked by another NADPH oxidase inhibitor (apocynin), nor the Src inhibitors PP1 or PP2, ruling out an action through the NADPH oxidase signalling pathway. Several features of the DPI-mediated suppression of agonist-evoked responses (i.e. suppression of peak magnitudes and unmasking of phasic activity) are similar to those of cyclopiazonic acid, an inhibitor of the internal Ca2+ pump. Direct measurement of microsomal Ca2+ uptake revealed that DPI modestly inhibits the internal Ca2+ pump. Conclusions and implications: DPI inhibits cholinesterase activity and the internal Ca2+ pump in tracheal smooth muscle. PMID:19788497

Monoamine oxidase inhibitors from Gentiana lutea.

PubMed

Haraguchi, Hiroyuki; Tanaka, Yasumasa; Kabbash, Amal; Fujioka, Toshihiro; Ishizu, Takashi; Yagi, Akira

2004-08-01

Three monoamine oxidase (MAO) inhibitors were isolated from Gentiana lutea. Their structures were elucidated to be 3-3''linked-(2'-hydroxy-4-O-isoprenylchalcone)-(2'''-hydroxy-4''-O-isoprenyldihydrochalcone) (1), 2-methoxy-3-(1,1'-dimethylallyl)-6a,10a-dihydrobenzo(1,2-c)chroman-6-one and 5-hydroxyflavanone. These compounds, and the hydrolysis product of 1, displayed competitive inhibitory properties against MAO-B which was more effective than MAO-A.

Pre-clinical evaluation of small molecule LOXL2 inhibitors in breast cancer

PubMed Central

Chang, Joan; Lucas, Morghan C.; Leonte, Lidia E.; Garcia-Montolio, Marc; Singh, Lukram Babloo; Findlay, Alison D.; Deodhar, Mandar; Foot, Jonathan S.; Jarolimek, Wolfgang; Timpson, Paul; Erler, Janine T.; Cox, Thomas R.

2017-01-01

Lysyl Oxidase-like 2 (LOXL2), a member of the lysyl oxidase family of amine oxidases is known to be important in normal tissue development and homeostasis, as well as the onset and progression of solid tumors. Here we tested the anti-tumor properties of two generations of novel small molecule LOXL2 inhibitor in the MDA-MB-231 human model of breast cancer. We confirmed a functional role for LOXL2 activity in the progression of primary breast cancer. Inhibition of LOXL2 activity inhibited the growth of primary tumors and reduced primary tumor angiogenesis. Dual inhibition of LOXL2 and LOX showed a greater effect and also led to a lower overall metastatic burden in the lung and liver. Our data provides the first evidence to support a role for LOXL2 specific small molecule inhibitors as a potential therapy in breast cancer. PMID:28199967

Inhibition of the NADPH oxidase regulates HO-1 expression in chronic myeloid leukemia

PubMed Central

Singh, Melissa M.; Irwin, Mary E.; Gao, Yin; Ban, Kechen; Shi, Ping; Arlinghaus, Ralph B.; Amin, Hesham M.; Chandra, Joya

2011-01-01

Background Patients with blast crisis phase chronic myelogeneous leukemia (CML) have poor response to tyrosine kinase inhibitors designed to inhibit the BCR-ABL1 oncogene. Recent work has shown that heme oxygenase 1 (HO-1) expression is increased in BCR-ABL1 expressing cells and that inhibition of HO-1 in CML leads to reduced cellular growth suggesting HO-1 may be a plausible target for therapy. Here we sought to clarify the mechanism of HO-1 overexpression and the role of the NADPH oxidase as a contributor to this mechanism in CML. Methods HO-1 expression was evaluated in CML bone marrow specimens from patients in various stages of disease, in a transplant based model for CML and in CML cell lines. Chemical and genetic inhibition of the NADPH oxidase was carried out in CML cells. Results Blast crisis CML patient specimens displayed higher levels of HO-1 staining than chronic or accelerated phase. HO-1 upregulation in BCR-ABL1 expressing cells was suppressed by diphenyliodonium (DPI), a chemical inhibitor of the NADPH oxidase. Targeting the NADPH oxidase through RNAi to Rac1, a dominant negative Rac1 construct or an inhibitor of Rac1 activity also blunted HO-1 protein expression. Moreover, inhibition of the NADPH oxidase by RNAi directed towards p47phox similarly abrogated HO-1 levels. Conclusion BCR-ABL1 expression upregulates HO-1, a survival factor for CML cells. This upregulation is more pronounced in blast crisis CML relative to early stage disease and is mediated by the NADPH oxidase components Rac1 and p47phox. Expression of p47phox is increased in BCR-ABL1 expressing cells. PMID:22139798

The structure and inhibition of human diamine oxidase†,‡

PubMed Central

McGrath, Aaron P; Hilmer, Kimberly M; Collyer, Charles A; Shepard, Eric M; Elmore, Bradley O.; Brown, Doreen E; Dooley, David M; Guss, J Mitchell

2009-01-01

Humans have three functioning genes that code for copper-containing amine oxidases. The product of the AOC1 gene is a so-called diamine oxidase (hDAO), named for its substrate preference for diamines, particularly histamine. hDAO has been cloned and expressed in insect cells and the structure of the native enzyme determined by X-ray crystallography to a resolution of 1.8 Å. The homodimeric structure has the archetypal amine oxidase fold. Two active sites, one in each subunit, are characterized by the presence of a copper ion and a topaquinone residue formed by the post-translational modification of a tyrosine. Although hDAO shares 37.9 % sequence identity with another human copper amine oxidase, semicarbazide sensitive amine oxidase or vascular adhesion protein-1, its substrate binding pocket and entry channel are distinctly different in accord with the different substrate specificities. The structures of two inhibitor complexes of hDAO, berenil and pentamidine, have been refined to resolutions of 2.1 Å and 2.2 Å, respectively. They bind non-covalently in the active site channel. The inhibitor binding suggests that an aspartic acid residue, conserved in all diamine oxidases but absent from other amine oxidases, is responsible for the diamine specificity by interacting with the second amino group of preferred diamine substrates. PMID:19764817

BK channels in innate immune functions of neutrophils and macrophages

PubMed Central

Essin, Kirill; Gollasch, Maik; Rolle, Susanne; Weissgerber, Patrick; Sausbier, Matthias; Bohn, Erwin; Autenrieth, Ingo B.; Ruth, Peter; Luft, Friedrich C.; Kettritz, Ralph

2009-01-01

Oxygen-dependent antimicrobial activity of human polymorphonuclear leukocytes (PMNs) relies on the phagocyte nicotinamide adenine dinucleotide phosphate (NADPH) oxidase to generate oxidants. As the oxidase transfers electrons from NADPH the membrane will depolarize and concomitantly terminate oxidase activity, unless there is charge translocation to compensate. Most experimental data implicate proton channels as the effectors of this charge compensation, although large-conductance Ca2+-activated K+ (BK) channels have been suggested to be essential for normal PMN antimicrobial activity. To test this latter notion, we directly assessed the role of BK channels in phagocyte function, including the NADPH oxidase. PMNs genetically lacking BK channels (BK−/−) had normal intracellular and extracellular NADPH oxidase activity in response to both receptor-independent and phagocytic challenges. Furthermore, NADPH oxidase activity of human PMNs and macrophages was normal after treatment with BK channel inhibitors. Although BK channel inhibitors suppressed endotoxin-mediated tumor necrosis factor-α secretion by bone marrow-derived macrophages (BMDMs), BMDMs of BK−/− and wild-type mice responded identically and exhibited the same ERK, PI3K/Akt, and nuclear factor-κB activation. Based on these data, we conclude that the BK channel is not required for NADPH oxidase activity in PMNs or macrophages or for endotoxin-triggered tumor necrosis factor-α release and signal transduction BMDMs. PMID:19074007

Structure-Activity Relationship Analysis of 3-phenylcoumarin-Based Monoamine Oxidase B Inhibitors

NASA Astrophysics Data System (ADS)

Rauhamäki, Sanna; Postila, Pekka A.; Niinivehmas, Sanna; Kortet, Sami; Schildt, Emmi; Pasanen, Mira; Manivannan, Elangovan; Ahinko, Mira; Koskimies, Pasi; Nyberg, Niina; Huuskonen, Pasi; Multamäki, Elina; Pasanen, Markku; Juvonen, Risto O.; Raunio, Hannu; Huuskonen, Juhani; Pentikäinen, Olli T.

2018-03-01

Monoamine oxidase B (MAO-B) catalyzes deamination of monoamines such as neurotransmitters dopamine and norepinephrine. Accordingly, small-molecule MAO-B inhibitors potentially alleviate the symptoms of dopamine-linked neuropathologies such as depression or Parkinson’s disease. Coumarin with a functionalized 3-phenyl ring system is a promising scaffold for building potent MAO-B inhibitors. Here, a vast set of 3-phenylcoumarin derivatives was designed using virtual combinatorial chemistry or rationally de novo and synthesized using microwave chemistry. The derivatives inhibited the MAO-B at 100 nM - 1 µM. The IC50 value of the most potent derivative 1 was 56 nM. A docking-based structure-activity relationship analysis summarizes the atom-level determinants of the MAO-B inhibition by the derivatives. Finally, the cross-reactivity of the derivatives was tested against monoamine oxidase A and a specific subset of enzymes linked to estradiol metabolism, known to have coumarin-based inhibitors. Overall, the results indicate that the 3-phenylcoumarins, especially derivative 1, present unique pharmacological features worth considering in future drug development.

Reactive Oxygen Species and Inhibitors of Inflammatory Enzymes, NADPH Oxidase, and iNOS in Experimental Models of Parkinson's Disease

PubMed Central

Koppula, Sushruta; Kumar, Hemant; Kim, In Su; Choi, Dong-Kug

2012-01-01

Reactive oxygen species (ROSs) are emerging as important players in the etiology of neurodegenerative disorders including Parkinson's disease (PD). Out of several ROS-generating systems, the inflammatory enzymes nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and inducible nitric oxide synthase (iNOS) were believed to play major roles. Mounting evidence suggests that activation of NADPH oxidase and the expression of iNOS are directly linked to the generation of highly reactive ROS which affects various cellular components and preferentially damage midbrain dopaminergic neurons in PD. Therefore, appropriate management or inhibition of ROS generated by these enzymes may represent a therapeutic target to reduce neuronal degeneration seen in PD. Here, we have summarized recently developed agents and patents claimed as inhibitors of NADPH oxidase and iNOS enzymes in experimental models of PD. PMID:22577256

Probing mammalian spermine oxidase enzyme-substrate complex through molecular modeling, site-directed mutagenesis and biochemical characterization.

PubMed

Tavladoraki, Paraskevi; Cervelli, Manuela; Antonangeli, Fabrizio; Minervini, Giovanni; Stano, Pasquale; Federico, Rodolfo; Mariottini, Paolo; Polticelli, Fabio

2011-04-01

Spermine oxidase (SMO) and acetylpolyamine oxidase (APAO) are FAD-dependent enzymes that are involved in the highly regulated pathways of polyamine biosynthesis and degradation. Polyamine content is strictly related to cell growth, and dysfunctions in polyamine metabolism have been linked with cancer. Specific inhibitors of SMO and APAO would allow analyzing the precise role of these enzymes in polyamine metabolism and related pathologies. However, none of the available polyamine oxidase inhibitors displays the desired characteristics of selective affinity and specificity. In addition, repeated efforts to obtain structural details at the atomic level on these two enzymes have all failed. In the present study, in an effort to better understand structure-function relationships, SMO enzyme-substrate complex has been probed through a combination of molecular modeling, site-directed mutagenesis and biochemical studies. Results obtained indicate that SMO binds spermine in a similar conformation as that observed in the yeast polyamine oxidase FMS1-spermine complex and demonstrate a major role for residues His82 and Lys367 in substrate binding and catalysis. In addition, the SMO enzyme-substrate complex highlights the presence of an active site pocket with highly polar characteristics, which may explain the different substrate specificity of SMO with respect to APAO and provide the basis for the design of specific inhibitors for SMO and APAO.

Specific Inhibition of the Cyanide-insensitive Respiratory Pathway in Plant Mitochondria by Hydroxamic Acids

PubMed Central

Schonbaum, Gregory R.; Bonner, Walter D.; Storey, Bayard T.; Bahr, James T.

1971-01-01

Hydroxamic acids, R-CONHOH, are inhibitors specific to the respiratory pathway through the alternate, cyanide-insensitive terminal oxidase of plant mitochondria. The nature of the R group in these compounds affects the concentration at which the hydroxamic acids are effective, but it appears that all hydroxamic acids inhibit if high enough concentrations are used. The benzhydroxamic acids are effective at relatively low concentrations; of these, the most effective are m-chlorobenzhydroxamic acid and m-iodobenzhydroxamic acid. The concentrations required for half-maximal inhibition of the alternate oxidase pathway in mung bean (Phaseolus aureus) mitochondria are 0.03 mm for m-chlorobenzhydroxamic acid and 0.02 mm for m-iodobenzhydroxamic acid. With skunk cabbage (Symplocarpus foetidus) mitochondria, the required concentrations are 0.16 for m-chlorobenzhydroxamic acid and 0.05 for m-iodobenzhydroxamic acid. At concentrations which inhibit completely the alternate oxidase pathway, these two compounds have no discernible effect on either the respiratory pathway through cytochrome oxidase, or on the energy coupling reactions of these mitochondria. These inhibitors make it possible to isolate the two respiratory pathways and study their mode of action separately. These inhibitors also enhance an electron paramagnetic resonance signal near g = 2 in anaerobic, submitochondrial particles from skunk cabbage, which appears to be specific to the alternate oxidase and thus provides a means for its assay. PMID:5543780

A Peroxidase-linked Spectrophotometric Assay for the Detection of Monoamine Oxidase Inhibitors

PubMed Central

Zhi, Kangkang; Yang, Zhongduo; Sheng, Jie; Shu, Zongmei; Shi, Yin

2016-01-01

To develop a new more accurate spectrophotometric method for detecting monoamine oxidase inhibitors from plant extracts, a series of amine substrates were selected and their ability to be oxidized by monoamine oxidase was evaluated by the HPLC method and a new substrate was used to develop a peroxidase-linked spectrophotometric assay. 4-(Trifluoromethyl) benzylamine (11) was proved to be an excellent substrate for peroxidase-linked spectrophotometric assay. Therefore, a new peroxidase-linked spectrophotometric assay was set up. The principle of the method is that the MAO converts 11 into aldehyde, ammonia and hydrogen peroxide. In the presence of peroxidase, the hydrogen peroxide will oxidize 4-aminoantipyrine into oxidised 4-aminoantipyrine which can condense with vanillic acid to give a red quinoneimine dye. The production of the quinoneimine dye was detected at 490 nm by a microplate reader. The ⊿OD value between the blank group and blank negative control group in this new method is twice as much as that in Holt’s method, which enables the procedure to be more accurate and avoids the produce of false positive results. The new method will be helpful for researchers to screening monoamine oxidase inhibitors from deep-color plant extracts. PMID:27610153

A Peroxidase-linked Spectrophotometric Assay for the Detection of Monoamine Oxidase Inhibitors.

PubMed

Zhi, Kangkang; Yang, Zhongduo; Sheng, Jie; Shu, Zongmei; Shi, Yin

2016-01-01

To develop a new more accurate spectrophotometric method for detecting monoamine oxidase inhibitors from plant extracts, a series of amine substrates were selected and their ability to be oxidized by monoamine oxidase was evaluated by the HPLC method and a new substrate was used to develop a peroxidase-linked spectrophotometric assay. 4-(Trifluoromethyl) benzylamine (11) was proved to be an excellent substrate for peroxidase-linked spectrophotometric assay. Therefore, a new peroxidase-linked spectrophotometric assay was set up. The principle of the method is that the MAO converts 11 into aldehyde, ammonia and hydrogen peroxide. In the presence of peroxidase, the hydrogen peroxide will oxidize 4-aminoantipyrine into oxidised 4-aminoantipyrine which can condense with vanillic acid to give a red quinoneimine dye. The production of the quinoneimine dye was detected at 490 nm by a microplate reader. The ⊿OD value between the blank group and blank negative control group in this new method is twice as much as that in Holt's method, which enables the procedure to be more accurate and avoids the produce of false positive results. The new method will be helpful for researchers to screening monoamine oxidase inhibitors from deep-color plant extracts.

Amperometric biosensor based on prussian blue and nafion modified screen-printed electrode for screening of potential xanthine oxidase inhibitors from medicinal plants.

PubMed

El Harrad, Loubna; Amine, Aziz

2016-04-01

A simple and sensitive amperometric biosensor was developed for the screening of potential xanthine oxidase inhibitors from medicinal plants. This biosensor was prepared by immobilization of xanthine oxidase on the surface of prussian blue modified screen-printed electrodes using nafion and glutaraldehyde. The developed biosensor showed a linear amperometric response at an applied potential of +0.05 V toward the detection of hypoxanthine from 5 μM to 45 μM with a detection limit of 0.4 μM (S/N=3) and its sensitivity was found to be 600 mA M(-1) cm(-2). In addition, the biosensor exhibited a good storage stability. The inhibition of xanthine oxidase by allopurinol was studied under the optimized conditions. The linear range of allopurinol concentration is obtained up to 2.5 μM with an estimated 50% of inhibitionI50=1.8 μM. The developed biosensor was successfully applied to the screening of xanthine oxidase inhibitors from 13 medicinal plants belonging to different families. Indeed, Moroccan people traditionally use these plants as infusion for the treatment of gout and its related symptoms. For this purpose, water extracts obtained from the infusion of these plants were used for the experiments. In this work, 13 extracts were assayed and several of them demonstrated xanthine oxidase inhibitory effect, with an inhibition greater than 50% compared to spectrophotometry measurements that only few extracts showed an inhibition greater than 50%. Copyright © 2016 Elsevier Inc. All rights reserved.

Reactive oxygen species are involved in regulating alpha1-adrenoceptor-activated vascular smooth muscle contraction.

PubMed

Tsai, Ming-Ho; Jiang, Meei Jyh

2010-08-23

Reactive oxygen species (ROS) were shown to mediate aberrant contractility in hypertension, yet the physiological roles of ROS in vascular smooth muscle contraction have remained elusive. This study aimed to examine whether ROS regulate alpha1-adrenoceptor-activated contraction by altering myosin phosphatase activities. Using endothelium-denuded rat tail artery (RTA) strips, effects of anti-oxidants on isometric force, ROS production, phosphorylation of the 20-kDa myosin light chain (MLC20), and myosin phosphatase stimulated by alpha1-adrenoceptor agonist phenylephrine were examined. An antioxidant, N-acetyl-L-cysteine (NAC), and two NADPH oxidase inhibitors, apocynin and VAS2870, dose-dependently inhibited contraction activated by phenylephrine. Phenylephrine stimulated superoxide anion production that was diminished by the pretreatment of apocynin, VAS2870, superoxide scavenger tiron or mitochondria inhibitor rotenone, but not by xanthine oxidase inhibitor allopurinol or cyclooxygenase inhibitor indomethacin. Concurrently, NADPH oxidase activity in RTA homogenates increased within 1 min upon phenylephrine stimulation, sustained for 10 min, and was abolished by the co-treatment with apocynin, but not allopurinol or rotenone. Phenylephrine-induced MLC20 phosphorylation was dose-dependently decreased by apocynin. Furthermore, apocynin inhibited phenylephrine-stimulated RhoA translocation to plasma membrane and phosphorylation of both myosin phosphatase regulatory subunit MYPT1Thr855 and myosin phosphatase inhibitor CPI-17Thr38. ROS, probably derived from NADPH oxidase and mitochondria, partially regulate alpha1-adrenoceptor-activated smooth muscle contraction by altering myosin phosphatase-mediated MLC20 phosphorylation through both RhoA/Rho kinase- and CPI-17-dependent pathways.

Correlation Between Monoamine Oxidase Inhibitors and Anticonvulsants

PubMed Central

Dwivedi, Chandradhar; Misra, Radhey S.; Chaudhari, Anshumali; Parmar, Surendra S.

1980-01-01

Monoamine oxidase inhibitory and anticonvulsant properties of 2-substituted styryl-6-bromo-3-(4-ethylbenzoate/4 benzhydrazide)-4-quinazoles are studied. All styryl quinazolone esters except compound number 9 exhibited monoamine oxidase inhibitory properties during oxidative deamination of kynuramine. Corresponding hydrazides were found to have relatively higher activity. All these quinazolones were able to protect against pentylenetetrazol induced seizures. These observations in general do not prove that monoamine oxidase inhibitory properties represent the biochemical basis for the anticonvulsant activity of these compounds. PMID:7420438

Polyphenol oxidase inhibitor(s) from German cockroach (Blattella germanica) extract

USDA-ARS?s Scientific Manuscript database

An extract from German cockroach appears effective in inhibiting browning on apples and potatoes. Successful identification of inhibitor(s) of PPO from German cockroach would be useful to the fruit and vegetable segments of the food industry, due to the losses they incur from enzymatic browning. Ide...

Structures of human monoamine oxidase B complexes with selective noncovalent inhibitors: safinamide and coumarin analogs.

PubMed

Binda, Claudia; Wang, Jin; Pisani, Leonardo; Caccia, Carla; Carotti, Angelo; Salvati, Patricia; Edmondson, Dale E; Mattevi, Andrea

2007-11-15

Structures of human monoamine oxidase B (MAO B) in complex with safinamide and two coumarin derivatives, all sharing a common benzyloxy substituent, were determined by X-ray crystallography. These compounds competitively inhibit MAO B with Ki values in the 0.1-0.5 microM range that are 30-700-fold lower than those observed with MAO A. The inhibitors bind noncovalently to MAO B, occupying both the entrance and the substrate cavities and showing a similarly oriented benzyloxy substituent.

The inhibition of amine oxidase and the central stimulating action of the stereoisomeric amphetamines and 1-phenylethylamines

PubMed Central

Grana, E.; Lilla, L.

1959-01-01

The stereoisomers of amphetamine and 1-phenylethylamine have been studied in the rat both as central stimulants and as inhibitors of amine oxidase from brain, liver, and kidney. There was no correlation between these two effects; thus it is unlikely that the central stimulating action of amphetamine is due to inhibition of amine oxidase. PMID:13828860

Novel arylalkenylpropargylamines as neuroprotective, potent, and selective monoamine oxidase B inhibitors for the treatment of Parkinson's disease.

PubMed

Huleatt, Paul B; Khoo, Mui Ling; Chua, Yi Yuan; Tan, Tiong Wei; Liew, Rou Shen; Balogh, Balázs; Deme, Ruth; Gölöncsér, Flóra; Magyar, Kalman; Sheela, David P; Ho, Han Kiat; Sperlágh, Beáta; Mátyus, Péter; Chai, Christina L L

2015-02-12

To develop novel neuroprotective agents, a library of novel arylalkenylpropargylamines was synthesized and tested for inhibitory activities against monoamine oxidases. From this, a number of highly potent and selective monoamine oxidase B inhibitors were identified. Selected compounds were also tested for neuroprotection in in vitro studies with PC-12 cells treated with 6-OHDA and rotenone, respectively. It was observed that some of the compounds tested yielded a marked increase in survival in PC-12 cells treated with the neurotoxins. This indicates that these propargylamines are able to confer protection against the effects of the toxins and may also be considered as novel disease-modifying anti-Parkinsonian agents, which are much needed for the therapy of Parkinson's disease.

Role of diamine oxidase during the treatment of tumour-bearing mice with combinations of polyamine anti-metabolites.

PubMed Central

Kallio, A; Jänne, J

1983-01-01

Treatment of mice bearing L1210 leukaemia with 2-difluoromethylornithine, a specific inhibitor of ornithine decarboxylase (EC 4.1.1.17), produced a profound depletion of putrescine and spermidine in the tumour cells. Sequential combination of methylglyoxal bis(guanylhydrazone), an inhibitor of adenosylmethionine decarboxylase (EC 4.1.1.50), with difluoromethylornithine largely reversed the polyamine depletion and led to a marked accumulation of cadaverine in the tumour cells. Experiments carried out with the combination of difluoromethylornithine and aminoguanidine, a potent inhibitor of diamine oxidase (EC 1.4.3.6), indicated that the methylglyoxal bis(guanylhydrazone)-induced reversal of polyamine depletion was mediated by the known inhibition of diamine oxidase by the diguanidine. In spite of the normalization of the tumour cell polyamine pattern upon administration of methylglyoxal bis(guanylhydrazone) to difluoromethylornithine-treated animals, the combination of these two drugs produced a growth-inhibitory effect not achievable with either of the compounds alone. PMID:6411077

Lesinurad

MedlinePlus

... oxidase inhibitor to treat hyperuricemia (high levels of uric acid) in people with gout (sudden attacks of redness, ... is in a class of medications called selective uric acid reabsorption inhibitors. It works by helping the kidneys ...

Serotonin produces monoamine oxidase-dependent oxidative stress in human heart valves.

PubMed

Peña-Silva, Ricardo A; Miller, Jordan D; Chu, Yi; Heistad, Donald D

2009-10-01

Heart valve disease and pulmonary hypertension, in patients with carcinoid tumors and people who used the fenfluramine-phentermine combination for weight control, have been associated with high levels of serotonin in blood. The mechanism by which serotonin induces valvular changes is not well understood. We recently reported that increased oxidative stress is associated with valvular changes in aortic valve stenosis in humans and mice. In this study, we tested the hypothesis that serotonin induces oxidative stress in human heart valves, and examined mechanisms by which serotonin may increase reactive oxygen species. Superoxide (O2*.-) was measured in heart valves from explanted human hearts that were not used for transplantation. (O2*.-) levels (lucigenin-enhanced chemoluminescence) were increased in homogenates of cardiac valves and blood vessels after incubation with serotonin. A nonspecific inhibitor of flavin-oxidases (diphenyliodonium), or inhibitors of monoamine oxidase [MAO (tranylcypromine and clorgyline)], prevented the serotonin-induced increase in (O2*.-). Dopamine, another MAO substrate that is increased in patients with carcinoid syndrome, also increased (O2*.-) levels in heart valves, and this effect was attenuated by clorgyline. Apocynin [an inhibitor of NAD(P)H oxidase] did not prevent increases in (O2*.-) during serotonin treatment. Addition of serotonin to recombinant human MAO-A generated (O2*.-), and this effect was prevented by an MAO inhibitor. In conclusion, we have identified a novel mechanism whereby MAO-A can contribute to increased oxidative stress in human heart valves and pulmonary artery exposed to serotonin and dopamine.

The opposite effect of isotype-selective monoamine oxidase inhibitors on adipogenesis in human bone marrow mesenchymal stem cells.

PubMed

Byun, Youngjoo; Park, Jongho; Hong, Soo Hyun; Han, Mi Hwa; Park, Suzie; Jung, Hyo-Il; Noh, Minsoo

2013-06-01

Adiponectin production during adipocyte differentiation of human bone marrow mesenchymal stem cells (hBM-MSCs) can be used to evaluate the pharmacological activity of anti-diabetic drugs to improve insulin sensitivity. Monoamine oxidase (MAO) inhibitors such as phenelzine and pargyline inhibit adipogenesis in murine pre-adipocytes. In this study, however, we found that selective MAO-A inhibitors, moclobemide and Ro41-1049, and a selective MAO-B inhibitor, selegiline, promoted adiponectin production during adipocyte differentiation in hBM-MSCs, which suggested the anti-diabetic potential of these drugs. In contrast, non-selective MAO inhibitors, phenelzine and tranylcypromine, inhibited adipocyte differentiation of hBM-MSCs. Concomitant treatments of MAO-A and MAO-B selective inhibitors did not change the stimulatory effect on adiponectin production in hBM-MSCs. Taken together, the opposite effects of isotype-selective MAO inhibitors on adiponectin production during adipogenesis in hBM-MSCs may not be directly associated with the inhibitory effects of MAO, suggested that the structure of MAO inhibitors may contain a novel anti-diabetic pharmacophore. Copyright © 2013 Elsevier Ltd. All rights reserved.

Regulation of the nitric oxide oxidase activity of myeloperoxidase by pharmacological agents.

PubMed

Maiocchi, Sophie L; Morris, Jonathan C; Rees, Martin D; Thomas, Shane R

2017-07-01

The leukocyte-derived heme enzyme myeloperoxidase (MPO) is released extracellularly during inflammation and impairs nitric oxide (NO) bioavailability by directly oxidizing NO or producing NO-consuming substrate radicals. Here, structurally diverse pharmacological agents with activities as MPO substrates/inhibitors or antioxidants were screened for their effects on MPO NO oxidase activity in human plasma and physiological model systems containing endogenous MPO substrates/antioxidants (tyrosine, urate, ascorbate). Hydrazide-based irreversible/reversible MPO inhibitors (4-ABAH, isoniazid) or the sickle cell anaemia drug, hydroxyurea, all promoted MPO NO oxidase activity. This involved the capacity of NO to antagonize MPO inhibition by hydrazide-derived radicals and/or the ability of drug-derived radicals to stimulate MPO turnover thereby increasing NO consumption by MPO redox intermediates or NO-consuming radicals. In contrast, the mechanism-based irreversible MPO inhibitor 2-thioxanthine, potently inhibited MPO turnover and NO consumption. Although the phenolics acetaminophen and resveratrol initially increased MPO turnover and NO consumption, they limited the overall extent of NO loss by rapidly depleting H 2 O 2 and promoting the formation of ascorbyl radicals, which inefficiently consume NO. The vitamin E analogue trolox inhibited MPO NO oxidase activity in ascorbate-depleted fluids by scavenging NO-consuming tyrosyl and urate radicals. Tempol and related nitroxides decreased NO consumption in ascorbate-replete fluids by scavenging MPO-derived ascorbyl radicals. Indoles or apocynin yielded marginal effects. Kinetic analyses rationalized differences in drug activities and identified criteria for the improved inhibition of MPO NO oxidase activity. This study reveals that widely used agents have important implications for MPO NO oxidase activity under physiological conditions, highlighting new pharmacological strategies for preserving NO bioavailability during inflammation. Copyright © 2017 Elsevier Inc. All rights reserved.

Efficacy, safety, and patient preference of monoamine oxidase B inhibitors in the treatment of Parkinson’s disease

PubMed Central

Robottom, Bradley J

2011-01-01

Parkinson’s disease (PD) is the second most common neurodegenerative disease and the most treatable. Treatment of PD is symptomatic and generally focuses on the replacement or augmentation of levodopa. A number of options are available for treatment, both in monotherapy of early PD and to treat complications of advanced PD. This review focuses on rasagiline and selegiline, two medications that belong to a class of antiparkinsonian drugs called monoamine oxidase B (MAO-B) inhibitors. Topics covered in the review include mechanism of action, efficacy in early and advanced PD, effects on disability, the controversy regarding disease modification, safety, and patient preference for MAO-B inhibitors. PMID:21423589

Efficacy, safety, and patient preference of monoamine oxidase B inhibitors in the treatment of Parkinson's disease.

PubMed

Robottom, Bradley J

2011-01-20

Parkinson's disease (PD) is the second most common neurodegenerative disease and the most treatable. Treatment of PD is symptomatic and generally focuses on the replacement or augmentation of levodopa. A number of options are available for treatment, both in monotherapy of early PD and to treat complications of advanced PD. This review focuses on rasagiline and selegiline, two medications that belong to a class of antiparkinsonian drugs called monoamine oxidase B (MAO-B) inhibitors. Topics covered in the review include mechanism of action, efficacy in early and advanced PD, effects on disability, the controversy regarding disease modification, safety, and patient preference for MAO-B inhibitors.

The amine oxidase inhibitor phenelzine limits lipogenesis in adipocytes without inhibiting insulin action on glucose uptake.

PubMed

Carpéné, Christian; Grès, Sandra; Rascalou, Simon

2013-06-01

The antidepressant phenelzine is a monoamine oxidase inhibitor known to inhibit various other enzymes, among them semicarbazide-sensitive amine oxidase (currently named primary amine oxidase: SSAO/PrAO), absent from neurones but abundant in adipocytes. It has been reported that phenelzine inhibits adipocyte differentiation of cultured preadipocytes. To further explore the involved mechanisms, our aim was to study in vitro the acute effects of phenelzine on de novo lipogenesis in mature fat cells. Therefore, glucose uptake and incorporation into lipid were measured in mouse adipocytes in response to phenelzine, other hydrazine-based SSAO/PrAO-inhibitors, and reference agents. None of the inhibitors was able to impair the sevenfold activation of 2-deoxyglucose uptake induced by insulin. Phenelzine did not hamper the effect of lower doses of insulin. However, insulin-stimulated glucose incorporation into lipids was dose-dependently inhibited by phenelzine and pentamidine, but not by semicarbazide or BTT2052. In contrast, all these SSAO/PrAO inhibitors abolished the transport and lipogenesis stimulation induced by benzylamine. These data indicate that phenelzine does not inhibit glucose transport, the first step of lipogenesis, but inhibits at 100 μM the intracellular triacylglycerol assembly, consistently with its long-term anti-adipogenic effect and such rapid action was not found with all the hydrazine derivatives tested. Therefore, the alterations of body weight control consecutive to the use of this antidepressant drug might be not only related to central effects on food intake/energy expenditure, but could also depend on its direct action in adipocytes. Nonetheless, phenelzine antilipogenic action is not merely dependent on SSAO/PrAO inhibition.

Discovery of isatin and 1H-indazol-3-ol derivatives as d-amino acid oxidase (DAAO) inhibitors.

PubMed

Szilágyi, Bence; Kovács, Péter; Ferenczy, György G; Rácz, Anita; Németh, Krisztina; Visy, Júlia; Szabó, Pál; Ilas, Janez; Balogh, György T; Monostory, Katalin; Vincze, István; Tábi, Tamás; Szökő, Éva; Keserű, György M

2018-05-01

d-Amino acid oxidase (DAAO) is a potential target in the treatment of schizophrenia as its inhibition increases brain d-serine level and thus contributes to NMDA receptor activation. Inhibitors of DAAO were sought testing [6+5] type heterocycles and identified isatin derivatives as micromolar DAAO inhibitors. A pharmacophore and structure-activity relationship analysis of isatins and reported DAAO inhibitors led us to investigate 1H-indazol-3-ol derivatives and nanomolar inhibitors were identified. The series was further characterized by pK a and isothermal titration calorimetry measurements. Representative compounds exhibited beneficial properties in in vitro metabolic stability and PAMPA assays. 6-fluoro-1H-indazol-3-ol (37) significantly increased plasma d-serine level in an in vivo study on mice. These results show that the 1H-indazol-3-ol series represents a novel class of DAAO inhibitors with the potential to develop drug candidates. Copyright © 2018 Elsevier Ltd. All rights reserved.

Defining the Role of the Monoamine Oxidase-B Inhibitors for Parkinson's Disease.

PubMed

Robakis, Daphne; Fahn, Stanley

2015-06-01

Inhibitors of monoamine oxidase-B (MAO-B) occupy an important place in the treatment of Parkinson's disease. Selegiline was the first MAO-B to be used therapeutically, while rasagiline is a second-generation drug with higher potency and selectivity. Safinamide is an investigational MAO-B inhibitor with non-dopaminergic properties that may provide advantages over its predecessors. As a class, MAO-B inhibitors are safe and well tolerated and provide symptomatic benefit both as monotherapy and in combination with other antiparkinsonian medications from early to late stages of disease. In combination with levodopa, MAO-B inhibitors may improve motor fluctuations and allow for lower total doses of levodopa. Patient characteristics and preferences can be important factors in deciding between agents. As a class, MAO-B inhibitors have shown promise as disease-modifying agents, but the clinical trial evidence to date has not been strong enough to afford them such a label. Future research may help further elucidate their relative merits and clarify their role in altering disease progression.

Design and synthesis of chalcone derivatives as potential non-purine xanthine oxidase inhibitors.

PubMed

Bui, Trung Huu; Nguyen, Nhan Trung; Dang, Phu Hoang; Nguyen, Hai Xuan; Nguyen, Mai Thanh Thi

2016-01-01

Based on some previous research, the chalcone derivatives exhibited potent xanthine oxidase inhibitory activity, e.g. sappanchalcone ( 7 ), with IC 50 value of 3.9 μM, was isolated from Caesalpinia sappan . Therefore, objectives of this research are design and synthesis of 7 and other chalcone derivatives by Claisen-Schmidt condensation and then evaluate their XO inhibitory activity. Fifteen chalcone derivatives were synthesized by Claisen-Schmidt condensation, and were evaluated for XO inhibitory activity. Nine out of 15 synthetic chalcones showed inhibitory activity ( 3 ; 5 - 8 ; 10 - 13 ). Sappanchalcone derivatives ( 11 ) (IC 50 , 2.5 μM) and a novel chalcone ( 13 ) (IC 50 , 2.4 μM) displayed strong xanthine oxidase inhibitory activity that is comparable to allopurinol (IC 50 , 2.5 μM). The structure-activity relationship of these chalcone derivatives was also presented. It is the first research on synthesis sappanchalcone ( 7 ) by Claisen-Schmidt condensation. The overall yield of this procedure was 6.6 %, higher than that of reported procedure (4 %). Design, synthesis, and evaluation of chalcone derivatives were carried out. This result suggests that the chalcone derivative can be used as potential non-purine XO inhibitors.Graphical abstractThe chalcone derivatives as potential non-purine xanthine oxidase inhibitors.

Role of catechins on ET-1 induced stimulation of PLD and NADPH oxidase activities in pulmonary smooth muscle cells: Determination of the probable mechanism by molecular docking studies.

PubMed

Chakraborti, Sajal; Sarkar, Jaganmay; Bhuyan, Rajabrata; Chakraborti, Tapati

2017-12-05

Treatment of human pulmonary artery smooth muscle cells with ET-1 stimulated PLD and NADPH oxidase activities, which were inhibited upon pretreatment with bosentan (ET-1 receptor antagonist), FIPI (PLD inhibitor), apocynin (NADPH oxidase inhibitor) and EGCG & ECG (catechins having galloyl group), but not EGC & EC (catechins devoid of galloyl group). Herein, we determined the probable mechanism by which the galloyl group containing catechins inhibit ET-1 induced stimulation of PLD activity by molecular docking analyses based on our biochemical studies. ET-1 induced stimulation of PLD activity was inhibited by SecinH3 (inhibitor of cytohesin). Arf-6 and cytohesin-1 were associated in the cell membrane, which was not inhibited by the catechins during ET-1 treatment to the cells. However, EGCG and ECG inhibited binding of GTPγS with Arf-6 even in presence of cytohesin-1. The molecular docking analyses revealed that the galloyl group containing catechins (EGCG/ECG) with cytohesin1-Arf6GDP, but not the non-galloyl-containing catechins (EGC and EC), prevents GDP/GTP exchange in Arf-6 which seems to be an important mechanism for inhibition of ET-1 induced activation of PLD and subsequently increase in NADPH oxidase activities.

A point mutation of valine-311 to methionine in Bacillus subtilis protoporphyrinogen oxidase does not greatly increase resistance to the diphenyl ether herbicide oxyfluorfen.

PubMed

Jeong, Eunjoo; Houn, Thavrak; Kuk, Yongin; Kim, Eun-Seon; Chandru, Hema Kumar; Baik, Myunggi; Back, Kyoungwhan; Guh, Ja-Ock; Han, Oksoo

2003-10-01

In an effort to asses the effect of Val311Met point mutation of Bacillus subtilis protoporphyrinogen oxidase on the resistance to diphenyl ether herbicides, a Val311Met point mutant of B. subtilis protoporphyrinogen oxidase was prepared, heterologously expressed in Escherichia coli, and the purified recombinant Val311Met mutant protoporphyrinogen oxidase was kinetically characterized. The mutant protoporphyrinogen oxidase showed very similar kinetic patterns to wild type protoporphyrinogen oxidase, with slightly decreased activity dependent on pH and the concentrations of NaCl, Tween 20, and imidazole. When oxyfluorfen was used as a competitive inhibitor, the Val311Met mutant protoporphyrinogen oxidase showed an increased inhibition constant about 1.5 times that of wild type protoporphyrinogen oxidase. The marginal increase of the inhibition constant indicates that the Val311Met point mutation in B. subtilis protoporphyrinogen oxidase may not be an important determinant in the mechanism that protects protoporphyrinogen oxidase against diphenyl ether herbicides.

Calcium mobilization and Rac1 activation are required for VCAM-1 (vascular cell adhesion molecule-1) stimulation of NADPH oxidase activity.

PubMed Central

Cook-Mills, Joan M; Johnson, Jacob D; Deem, Tracy L; Ochi, Atsuo; Wang, Lei; Zheng, Yi

2004-01-01

VCAM-1 (vascular cell adhesion molecule-1) plays an important role in the regulation of inflammation in atherosclerosis, asthma, inflammatory bowel disease and transplantation. VCAM-1 activates endothelial cell NADPH oxidase, and this oxidase activity is required for VCAM-1-dependent lymphocyte migration. We reported previously that a mouse microvascular endothelial cell line promotes lymphocyte migration that is dependent on VCAM-1, but not on other known adhesion molecules. Here we have investigated the signalling mechanisms underlying VCAM-1 function. Lymphocyte binding to VCAM-1 on the endothelial cell surface activated an endothelial cell calcium flux that could be inhibited with anti-alpha4-integrin and mimicked by anti-VCAM-1-coated beads. VCAM-1 stimulation of calcium responses could be blocked by an inhibitor of intracellular calcium mobilization, a calcium channel inhibitor or a calcium chelator, resulting in the inhibition of NADPH oxidase activity. Addition of ionomycin overcame the calcium channel blocker suppression of VCAM-1-stimulated NADPH oxidase activity, but could not reverse the inhibitory effect imposed by intracellular calcium blockage, indicating that both intracellular and extracellular calcium mobilization are required for VCAM-1-mediated activation of NADPH oxidase. Furthermore, VCAM-1 specifically activated the Rho-family GTPase Rac1, and VCAM-1 activation of NADPH oxidase was blocked by a dominant negative Rac1. Thus VCAM-1 stimulates the mobilization of intracellular and extracellular calcium and Rac1 activity that are required for the activation of NADPH oxidase. PMID:14594451

Neovascularization in an arterio-venous loop-containing tissue engineering chamber: role of NADPH oxidase

PubMed Central

Jiang, F; Zhang, G; Hashimoto, I; Kumar, B S; Bortolotto, S; Morrison, W A; Dusting, G J

2008-01-01

Using an in vivo arterio-venous loop-containing tissue-engineering chamber, we have created a variety of vascularized tissue blocks, including functional myocardium. The viability of the transplanted cells is limited by the rate of neovascularization in the chamber. A Nox2-containing nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is thought to have a critical role in ischaemic angiogenesis. In this study we investigated whether NADPH oxidase is involved in the neovascularization process in the tissue-engineering chamber. New blood vessels originating from the venous and the arterial ends of the loop could be identified after 3 days, and the vessel density (by lectin staining) peaked after 7 days and was maintained for at least 14 days. This was accompanied by granulation tissue formation and concomitant increase in the mRNA level of Nox4 NADPH oxidase. Although the total level of Nox2 mRNA in the chamber tissue decreased from day 3 to day 7, immunohistochemistry identified a strong expression of Nox2 in the endothelial cells of the new vessels. In human microvascular endothelial cells, the NADPH oxidase inhibitor apocynin reduced NADPH oxidase activity and inhibited the angiogenic responses in vitro. Local treatment with the NADPH oxidase inhibitors apocynin or gp91ds-tat peptide significantly suppressed the vessel growth in the chamber. In conclusion, NADPH oxidase-dependent redox signalling is important for neovascularization in this novel tissue-engineering chamber in vivo, and boosting this signalling might be a new approach to extending vascularization and tissue growth. PMID:19012731

Indanones as high-potency reversible inhibitors of monoamine oxidase.

PubMed

Mostert, Samantha; Petzer, Anél; Petzer, Jacobus P

2015-05-01

Recent reports document that α-tetralone (3,4-dihydro-2H-naphthalen-1-one) is an appropriate scaffold for the design of high-potency monoamine oxidase (MAO) inhibitors. Based on the structural similarity between α-tetralone and 1-indanone, the present study involved synthesis of 34 1-indanone and related indane derivatives as potential inhibitors of recombinant human MAO-A and MAO-B. The results show that C6-substituted indanones are particularly potent and selective MAO-B inhibitors, with IC50 values ranging from 0.001 to 0.030 μM. C5-Substituted indanone and indane derivatives are comparatively weaker MAO-B inhibitors. Although the 1-indanone and indane derivatives are selective inhibitors of the MAO-B isoform, a number of homologues are also potent MAO-A inhibitors, with three homologues possessing IC50 values <0.1 μM. Dialysis of enzyme-inhibitor mixtures further established a selected 1-indanone as a reversible MAO inhibitor with a competitive mode of inhibition. It may be concluded that 1-indanones are promising leads for the design of therapies for neurodegenerative and neuropsychiatric disorders such as Parkinson's disease and depression. © 2015 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Quinolinic Carboxylic Acid Derivatives as Potential Multi-target Compounds for Neurodegeneration: Monoamine Oxidase and Cholinesterase Inhibition.

PubMed

Khan, Nehal A; Khan, Imtiaz; Abid, Syed M A; Zaib, Sumera; Ibrar, Aliya; Andleeb, Hina; Hameed, Shahid; Iqbal, Jamshed

2018-01-01

Parkinson's disease (PD), a debilitating and progressive disorder, is among the most challenging and devastating neurodegenerative diseases predominantly affecting the people over 60 years of age. To confront PD, an advanced and operational strategy is to design single chemical functionality able to control more than one target instantaneously. In this endeavor, for the exploration of new and efficient inhibitors of Parkinson's disease, we synthesized a series of quinoline carboxylic acids (3a-j) and evaluated their in vitro monoamine oxidase and cholinesterase inhibitory activities. The molecular docking and in silico studies of the most potent inhibitors were performed to identify the probable binding modes in the active site of the monoamine oxidase enzymes. Moreover, molecular properties were calculated to evaluate the druglikeness of the compounds. The biological evaluation results revealed that the tested compounds were highly potent against monoamine oxidase (A & B), 3c targeted both the isoforms of MAO with IC50 values of 0.51 ± 0.12 and 0.51 ± 0.03 µM, respectively. The tested compounds also demonstrated high and completely selective inhibitory action against acetylcholinesterase (AChE) with IC50 values ranging from 4.36 to 89.24 µM. Among the examined derivatives, 3i was recognized as the most potent inhibitor of AChE with an IC50 value of 4.36 ± 0.12 ±µM. The compounds appear to be promising inhibitors and could be used for the future development of drugs targeting neurodegenerative disorders. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Enhanced central serotonin release from slices of rat hypothalamus following repeated nialamide administration: evidence supporting the overactive serotonin receptor theory of depression

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

Offord, S.J.

1986-01-01

Researchers are suggesting unipolar affective disorders may be related to an abnormality in biogenic amine receptor-sensitivity. This abnormality may be a result of a dysfunction in central serotonin (5-HT) release mechanisms. 5-HT neurotransmission is modulated by presynaptic autoreceptors, which are members of the 5-HT/sub 1/ receptor subtype. The autoreceptor is thought to play an important role in the homeostasis of the central 5-HT synapse and could be a site at which some antidepressants mediate their therapeutic effect. The number of 5-HT/sub 1/ type receptor binding sites are reduced and behavior mediated by this receptor is abolished following repeated injections ofmore » monoamine oxidase inhibitor type antidepressants. These changes did not occur following a single injection. It was hypothesized that repeated treatment with a monoamine oxidase inhibitor would reduce the sensitivity of 5-HT autoreceptors and enhance 5-HT release. Rats were pretreated with single or repeated (twice daily for 7 days) intraperitoneal injections of nialamide (40 mg/kg) or chlorimipramine (10 mg/kg) and the ability of the autoreceptor agonist to inhibit potassium-induced /sup 3/H-5-HT release was evaluated using an in vitro superfusion system. These changes in 5-HT autoreceptor activity are consistent with other reports evaluating monoamine oxidase inhibitors on 5-HT/sub 1/ type receptors. It is hypothesized that the changes in 5-HT neurotransmission are related to the antidepressant mechanism of monoamine oxidase inhibitors.« less

Cross-talk between NADPH oxidase-PKCα-p(38)MAPK and NF-κB-MT1MMP in activating proMMP-2 by ET-1 in pulmonary artery smooth muscle cells.

PubMed

Sarkar, Jaganmay; Chowdhury, Animesh; Chakraborti, Tapati; Chakraborti, Sajal

2016-04-01

Treatment of bovine pulmonary artery smooth muscle cells with endothelin-1 (ET-1) caused an increase in the expression and activation of proMMP-2 in the cells. The present study was undertaken to determine the underlying mechanisms involved in this scenario. We demonstrated that (i) pretreatment with NADPH oxidase inhibitor, apocynin; PKC-α inhibitor, Go6976; p(38)MAPK inhibitor SB203580 and NF-κB inhibitor, Bay11-7082 inhibited the expression and activation of proMMP-2 induced by ET-1; (ii) ET-1 treatment to the cells stimulated NADPH oxidase and PKCα activity, p(38)MAPK phosphorylation as well as NF-κB activation by translocation of NF-κBp65 subunit from cytosol to the nucleus, and subsequently by increasing its DNA-binding activity; (iii) ET-1 increases MT1-MMP expression, which was inhibited upon pretreatment with apocynin, Go6976, SB293580, and Bay 11-7082; (iv) ET-1 treatment to the cells downregulated TIMP-2 level. Although apocynin and Go6976 pretreatment reversed ET-1 effect on TIMP-2 level, yet pretreatment of the cells with SB203580 and Bay 11-7082 did not show any discernible change in TIMP-2 level by ET-1. Overall, our results suggest that ET-1-induced activation of proMMP-2 is mediated via cross-talk between NADPH oxidase-PKCα-p(38)MAPK and NFκB-MT1MMP signaling pathways along with a marked decrease in TIMP-2 expression in the cells.

NADPH oxidase activation contributes to native low-density lipoprotein-induced proliferation of human aortic smooth muscle cells.

PubMed

Park, Il Hwan; Hwang, Hye Mi; Jeon, Byeong Hwa; Kwon, Hyung-Joo; Hoe, Kwang Lae; Kim, Young Myeong; Ryoo, Sungwoo

2015-06-12

Elevated plasma concentration of native low-density lipoprotein (nLDL) is associated with vascular smooth muscle cell (VSMC) activation and cardiovascular disease. We investigated the mechanisms of superoxide generation and its contribution to pathophysiological cell proliferation in response to nLDL stimulation. Lucigenin-induced chemiluminescence was used to measure nLDL-induced superoxide production in human aortic smooth muscle cells (hAoSMCs). Superoxide production was increased by nicotinamide adenine dinucleotide phosphate (NADPH) and decreased by NADPH oxidase inhibitors in nLDL-stimulated hAoSMC and hAoSMC homogenates, as well as in prepared membrane fractions. Extracellular signal-regulated kinase 1/2 (Erk1/2), protein kinase C-θ (PKCθ) and protein kinase C-β (PKCβ) were phosphorylated and maximally activated within 3 min of nLDL stimulation. Phosphorylated Erk1/2 mitogen-activated protein kinase, PKCθ and PKCβ stimulated interactions between p47phox and p22phox; these interactions were prevented by MEK and PKC inhibitors (PD98059 and calphostin C, respectively). These inhibitors decreased nLDL-dependent superoxide production and blocked translocation of p47phox to the membrane, as shown by epifluorescence imaging and cellular fractionation experiments. Proliferation assays showed that a small interfering RNA against p47phox, as well as superoxide scavenger and NADPH oxidase inhibitors, blocked nLDL-induced hAoSMC proliferation. The nLDL stimulation in deendothelialized aortic rings from C57BL/6J mice increased dihydroethidine fluorescence and induced p47phox translocation that was blocked by PD98059 or calphostin C. Isolated aortic SMCs from p47phox(-/-) mice (mAoSMCs) did not respond to nLDL stimulation. Furthermore, NADPH oxidase 1 (Nox1) was responsible for superoxide generation and cell proliferation in nLDL-stimulated hAoSMCs. These data demonstrated that NADPH oxidase activation contributed to cell proliferation in nLDL-stimulated hAoSMCs.

Molecular Insights into Human Monoamine Oxidase B Inhibition by the Glitazone Antidiabetes Drugs

PubMed Central

2011-01-01

The widely employed antidiabetic drug pioglitazone (Actos) is shown to be a specific and reversible inhibitor of human monoamine oxidase B (MAO B). The crystal structure of the enzyme–inhibitor complex shows that the R-enantiomer is bound with the thiazolidinedione ring near the flavin. The molecule occupies both substrate and entrance cavities of the active site, establishing noncovalent interactions with the surrounding amino acids. These binding properties differentiate pioglitazone from the clinically used MAO inhibitors, which act through covalent inhibition mechanisms and do not exhibit a high degree of MAO A versus B selectivity. Rosiglitazone (Avandia) and troglitazone, other members of the glitazone class, are less selective in that they are weaker inhibitors of both MAO A and MAO B. These results suggest that pioglitazone may have utility as a “repurposed” neuroprotectant drug in retarding the progression of disease in Parkinson's patients. They also provide new insights for the development of reversible isoenzyme-specific MAO inhibitors. PMID:22282722

Lipid-derived free radical production in superantigen-induced interstitial pneumonia

PubMed Central

Miyakawa, Hisako; Mason, Ronald P.; Jiang, JinJie; Kadiiska, Maria B.

2009-01-01

We studied the free radical generation involved in the development of interstitial pneumonia (IP) in an animal model of autoimmune disease. We observed an electron spin resonance (ESR) spectrum of α-(4-pyridyl-1-oxide)-N-tert-butylnitrone (POBN) radical adducts detected in the lipid extract of lungs in autoimmune-prone mice after intratracheal instillation of staphylococcal enterotoxin B. The POBN adducts detected by ESR were paralleled by infiltration of macrophages and neutrophils in the bronchoalveolar lavage fluid. To further investigate the mechanism of free radical generation, mice were pretreated with the macrophage toxicant gadolinium chloride, which significantly suppressed the radical generation. Free radical generation was also decreased by pretreatment with the xanthine oxidase (XO) inhibitor allopurinol, the iron chelator Desferal, and the inducible nitric oxide synthase (iNOS) inhibitor 1400W. Histopathologically, these drugs significantly reduced both the cell infiltration to alveolar septal walls and the synthesis of pulmonary collagen fibers. Experiments with NADPH oxidase knockout mice showed that NADPH oxidase did not contribute to lipid radical generation. These results suggest that lipid-derived carbon-centered free radical production is important in the manifestation of IP and that a macrophage toxicant, an XO inhibitor, an iron chelator, and an iNOS inhibitor protect against both radical generation and the manifestation of IP. PMID:19376221

Therapeutic Effects of Xanthine Oxidase Inhibitors: Renaissance Half a Century after the Discovery of Allopurinol

PubMed Central

PACHER, PÁL; NIVOROZHKIN, ALEX; SZABÓ, CSABA

2008-01-01

The prototypical xanthine oxidase (XO) inhibitor allopurinol, has been the cornerstone of the clinical management of gout and conditions associated with hyperuricemia for several decades. More recent data indicate that XO also plays an important role in various forms of ischemic and other types of tissue and vascular injuries, inflammatory diseases, and chronic heart failure. Allopurinol and its active metabolite oxypurinol showed considerable promise in the treatment of these conditions both in experimental animals and in small-scale human clinical trials. Although some of the beneficial effects of these compounds may be unrelated to the inhibition of the XO, the encouraging findings rekindled significant interest in the development of additional, novel series of XO inhibitors for various therapeutic indications. Here we present a critical overview of the effects of XO inhibitors in various pathophysiological conditions and also review the various emerging therapeutic strategies offered by this approach. PMID:16507884

Serotonin syndrome

MedlinePlus

... medicine). Drugs of abuse, such as ecstasy, LSD , cocaine , and amphetamines have also been associated with SS. ... can mimic those due to an overdose of cocaine, lithium, or an MAOI. If a person has ...

Identification and characterization of a novel flavin-containing spermine oxidase of mammalian cell origin.

PubMed Central

Vujcic, Slavoljub; Diegelman, Paula; Bacchi, Cyrus J; Kramer, Debora L; Porter, Carl W

2002-01-01

During polyamine catabolism, spermine and spermidine are first acetylated by spermidine/spermine N(1)-acetyltransferase (SSAT) and subsequently oxidized by polyamine oxidase (PAO) to produce spermidine and putrescine, respectively. In attempting to clone the PAO involved in this back-conversion pathway, we encountered an oxidase that preferentially cleaves spermine in the absence of prior acetylation by SSAT. A BLAST search using maize PAO sequences identified homologous mammalian cDNAs derived from human hepatoma and mouse mammary carcinoma: the encoded proteins differed by 20 amino acids. When either cDNA was transiently transfected into HEK-293 cells, intracellular spermine pools decreased by 75% while spermidine and N (1)-acetylspermidine pools increased, suggesting that spermine was selectively and directly oxidized by the enzyme. Substrate specificity using lysates of oxidase-transfected HEK-293 cells revealed that the newly identified oxidase strongly favoured spermine over N (1)-acetylspermine and that it failed to act on N (1)-acetylspermidine, spermidine or the preferred PAO substrate, N (1), N (12)-diacetylspermine. The PAO inhibitor, MDL-72,527, only partially blocked oxidation of spermine while a previously reported PAO substrate, N (1)-( n -octanesulphonyl)spermine, potently inhibited the reaction. Overall, the data indicate that the enzyme represents a novel mammalian oxidase which, on the basis of substrate specificity, we have designated spermine oxidase in order to distinguish it from the PAO involved in polyamine back-conversion. The identification of an enzyme capable of directly oxidizing spermine to spermidine has important implications for understanding polyamine homoeostasis and for interpreting metabolic and cellular responses to clinically relevant polyamine analogues and inhibitors. PMID:12141946

High resolution crystal structure of rat long chain hydroxy acid oxidase in complex with the inhibitor 4-carboxy-5-[(4-chlorophenyl)sulfanyl]-1, 2, 3-thiadiazole. Implications for inhibitor specificity and drug design.

PubMed

Chen, Zhi-wei; Vignaud, Caroline; Jaafar, Adil; Lévy, Bernard; Guéritte, Françoise; Guénard, Daniel; Lederer, Florence; Mathews, F Scott

2012-05-01

Long chain hydroxy acid oxidase (LCHAO) is responsible for the formation of methylguanidine, a toxic compound with elevated serum levels in patients with chronic renal failure. Its isozyme glycolate oxidase (GOX), has a role in the formation of oxalate, which can lead to pathological deposits of calcium oxalate, in particular in the disease primary hyperoxaluria. Inhibitors of these two enzymes may have therapeutic value. These enzymes are the only human members of the family of FMN-dependent l-2-hydroxy acid-oxidizing enzymes, with yeast flavocytochrome b(2) (Fcb2) among its well studied members. We screened a chemical library for inhibitors, using in parallel rat LCHAO, human GOX and the Fcb2 flavodehydrogenase domain (FDH). Among the hits was an inhibitor, CCPST, with an IC(50) in the micromolar range for all three enzymes. We report here the crystal structure of a complex between this compound and LCHAO at 1.3 Å resolution. In comparison with a lower resolution structure of this enzyme, binding of the inhibitor induces a conformational change in part of the TIM barrel loop 4, as well as protonation of the active site histidine. The CCPST interactions are compared with those it forms with human GOX and those formed by two other inhibitors with human GOX and spinach GOX. These compounds differ from CCPST in having the sulfur replaced with a nitrogen in the five-membered ring as well as different hydrophobic substituents. The possible reason for the ∼100-fold difference in affinity between these two series of inhibitors is discussed. The present results indicate that specificity is an issue in the quest for therapeutic inhibitors of either LCHAO or GOX, but they may give leads for this quest. Copyright © 2012 Elsevier Masson SAS. All rights reserved.

Calpain activation induced by glucose deprivation is mediated by oxidative stress and contributes to neuronal damage.

PubMed

Páramo, Blanca; Montiel, Teresa; Hernández-Espinosa, Diego R; Rivera-Martínez, Marlene; Morán, Julio; Massieu, Lourdes

2013-11-01

The mechanisms leading to neuronal death during glucose deprivation have not been fully elucidated, but a role of oxidative stress has been suggested. In the present study we have investigated whether the production of reactive oxygen species during glucose deprivation, contributes to the activation of calpain, a calcium-dependent protease involved in neuronal injury associated with brain ischemia and cerebral trauma. We have observed a rapid activation of calpain, as monitored by the cleavage of the cytoskeletal protein α-spectrin, after glucose withdrawal, which is reduced by inhibitors of xanthine oxidase, phospholipase A2 and NADPH oxidase. Results suggest that phospholipase A2 and NADPH oxidase contribute to the early activation of calpain after glucose deprivation. In particular NOX2, a member of the NADPH oxidase family is involved, since reduced stimulation of calpain activity is observed after glucose deprivation in hippocampal slices from transgenic mice lacking a functional NOX2. We observed an additive effect of the inhibitors of xanthine oxidase and phospholipase A2 on both ROS production and calpain activity, suggesting a synergistic action of these two enzymes. The present results provide new evidence showing that reactive oxygen species stimulate calpain activation during glucose deprivation and that this mechanism is involved in neuronal death. Copyright © 2013 Elsevier Ltd. All rights reserved.

In vitro study of 6-mercaptopurine oxidation catalysed by aldehyde oxidase and xanthine oxidase.

PubMed

Rashidi, Mohammad-Reza; Beedham, Christine; Smith, John S; Davaran, Soodabeh

2007-08-01

In spite of over 40 years of clinical use of 6-mercaptopurine, many aspects of complex pharmacology and metabolism of this drug remain unclear. It is thought that 6-mercaptopurine is oxidized to 6-thiouric acid through 6-thioxanthine or 8-oxo-6-mercaptopurine by one of two molybdenum hydroxylases, xanthine oxidase (XO), however, the role of other molybdenum hydroxylase, aldehyde oxidase (AO), in the oxidation of 6-mercaptopurine and possible interactions of AO substrates and inhibitors has not been investigated in more details. In the present study, the role of AO and XO in the oxidation of 6- mercaptopurine has been investigated. 6-mercaptopurine was incubated with bovine milk xanthine oxidase or partially purified guinea pig liver molybdenum hydroxylase fractions in the absence and presence of XO and AO inhibitor/substrates, and the reactions were monitored by spectrophotometric and HPLC methods. According to the results obtained from the inhibition studies, it is more likely that 6- mercaptopurine is oxidized to 6-thiouric acid via 6-thioxanthine rather than 8-oxo-6-mercaptopurine. The first step which is the rate limiting step is catalyzed solely by XO, whereas both XO and AO are involved in the oxidation of 6-thioxanthine to 6-thiouric acid.

In vitro xanthine oxidase inhibitory and in vivo hypouricemic activity of herbal coded formulation (Gouticin).

PubMed

Akram, Muhammad; Usmanghani, Khan; Ahmed, Iqbal; Azhar, Iqbal; Hamid, Abdul

2014-05-01

Currently, natural products have been used in treating gouty arthritis and are recognized as xanthine oxidase inhibitors. Current study was designed to evaluate in vitro xanthine oxidase inhibitory potential of Gouticin and its ingredients extracts and in vivo hypouricemic activity of gouticin tablet 500 mg twice daily. Ethanol extracts of Gouticin and its ingredients were evaluated in vitro, at 200, 100, 50, 25 μ g/ml concentrations for xanthine oxidase inhibitory activity. IC(50) values of Gouticin and its ingredients were estimated. Further, in vivo therapeutic effect of Gouticin was investigated in comparison with allopathic medicine (Allopurinol) to treat gout. Total patients were 200 that were divided into test and control group. Herbal coded medicine (Gouticin) was given to test group and allopathic medicine allopurinol was administered to control group. In vitro, Gouticin has the highest percent inhibition at 96% followed by Allopurinol with 93% inhibition. In vivo study, mean serum uric acid level of patients was 4.62 mg/dl and 5.21mg/dl by use of Gouticin and Allopurinol at end of therapy. The study showed that herbal coded formulation gouticin and its ingredients are potential sources of natural xanthine oxidase inhibitors. Gouticin 500 mg twice daily is more effective than the allopurinol 300mg once daily in the management of gout.

Rosuvastatin prevents angiotensin II-induced vascular changes by inhibition of NAD(P)H oxidase and COX-1

PubMed Central

Colucci, Rocchina; Fornai, Matteo; Duranti, Emiliano; Antonioli, Luca; Rugani, Ilaria; Aydinoglu, Fatma; Ippolito, Chiara; Segnani, Cristina; Bernardini, Nunzia; Taddei, Stefano; Blandizzi, Corrado; Virdis, Agostino

2013-01-01

Background and Purpose NAD(P)H oxidase and COX-1 participate in vascular damage induced by angiotensin II. We investigated the effect of rosuvastatin on endothelial dysfunction, vascular remodelling, changes in extracellular matrix components and mechanical properties of small mesenteric arteries from angiotensin II-infused rats. Experimental Approach Male rats received angiotensin II (120 ng·kg−1·min−1, subcutaneously) for 14 days with or without rosuvastatin (10 mg·kg−1·day−1, oral gavage) or vehicle. Vascular functions and morphological parameters were assessed by pressurized myography. Key Results In angiotensin II-infused rats, ACh-induced relaxation was attenuated compared with controls, less sensitive to L-NAME, enhanced by SC-560 (COX-1 inhibitor) or SQ-29548 (prostanoid TP receptor antagonist), and normalized by the antioxidant ascorbic acid or NAD(P)H oxidase inhibitors. After rosuvastatin, relaxations to ACh were normalized, fully sensitive to L-NAME, and no longer affected by SC-560, SQ-29548 or NAD(P)H oxidase inhibitors. Angiotensin II enhanced intravascular superoxide generation, eutrophic remodelling, collagen and fibronectin depositions, and decreased elastin content, resulting in increased vessel stiffness. All these changes were prevented by rosuvastatin. Angiotensin II increased phosphorylation of NAD(P)H oxidase subunit p47phox and its binding to subunit p67phox, effects inhibited by rosuvastatin. Rosuvastatin down-regulated vascular Nox4/NAD(P)H isoform and COX-1 expression, attenuated the vascular release of 6-keto-PGF1α, and enhanced copper/zinc-superoxide dismutase expression. Conclusion and Implications Rosuvastatin prevents angiotensin II-induced alterations in resistance arteries in terms of function, structure, mechanics and composition. These effects depend on restoration of NO availability, prevention of NAD(P)H oxidase-derived oxidant excess, reversal of COX-1 induction and its prostanoid production, and stimulation of endogenous vascular antioxidant defences. PMID:22817606

Importance of NADPH oxidase-mediated redox signaling in the detrimental effect of CRP on pancreatic insulin secretion.

PubMed

Chan, Pei-Chi; Wang, Ya-Chin; Chen, Yi-Ling; Hsu, Wan-Ning; Tian, Yu-Feng; Hsieh, Po-Shiuan

2017-11-01

Elevations in C-reactive protein (CRP) levels are positively correlated with the progress of type 2 diabetes mellitus. However, the effect of CRP on pancreatic insulin secretion is unknown. Here, we showed that purified human CRP impaired insulin secretion in isolated mouse islets and NIT-1 insulin-secreting cells in dose- and time-dependent manners. CRP increased NADPH oxidase-mediated ROS (reactive oxygen species) production, which simultaneously promoted the production of nitrotyrosine (an indicator of RNS, reactive nitrogen species) and TNFα, to diminish cell viability, insulin secretion in islets and insulin-secreting cells. These CRP-mediated detrimental effects on cell viability and insulin secretion were significantly reversed by adding NAC (a potent antioxidant), apocynin (a selective NADPH oxidase inhibitor), L-NAME (a non-selective nitric oxide synthase (NOS) inhibitor), aminoguanidine (a selective iNOS inhibitor), PDTC (a selective NFκB inhibitor) or Enbrel (an anti-TNFα fusion protein). However, CRP-induced ROS production failed to change after adding L-NAME, aminoguanidine or PDTC. In isolated islets and NIT-1 cells, the elevated nitrotyrosine contents by CRP pretreatment were significantly suppressed by adding L-NAME but not PDTC. Conversely, CRP-induced increases in TNF-α production were significantly reversed by administration of PDTC but not L-NAME. In addition, wild-type mice treated with purified human CRP showed significant decreases in the insulin secretion index (HOMA-β cells) and the insulin stimulation index in isolated islets that were reversed by the addition of L-NAME, aminoguanidine or NAC. It is suggested that CRP-activated NADPH-oxidase redox signaling triggers iNOS-mediated RNS and NFκB-mediated proinflammatory cytokine production to cause β cell damage in state of inflammation. Copyright © 2017 Elsevier Inc. All rights reserved.

Spermidine-mediated hydrogen peroxide signaling enhances the antioxidant capacity of salt-stressed cucumber roots.

PubMed

Wu, Jianqiang; Shu, Sheng; Li, Chengcheng; Sun, Jin; Guo, Shirong

2018-07-01

Hydrogen peroxide (H 2 O 2 ) is a key signaling molecule that mediates a variety of physiological processes and defense responses against abiotic stress in higher plants. In this study, our aims are to clarify the role of H 2 O 2 accumulation induced by the exogenous application of spermidine (Spd) to cucumber (Cucumis sativus) seedlings in regulating the antioxidant capacity of roots under salt stress. The results showed that Spd caused a significant increase in endogenous polyamines and H 2 O 2 levels, and peaked at 2 h after salt stress. Spd-induced H 2 O 2 accumulation was blocked under salt stress by pretreatment with a H 2 O 2 scavenger and respective inhibitors of cell wall peroxidase (CWPOD; EC: 1.11.1.7), polyamine oxidase (PAO; EC: 1.5.3.11) and NADPH oxidase (NOX; EC: 1.6.3.1); among these three inhibitors, the largest decrease was found in response to the addition of the inhibitor of polyamine oxidase. In addition, we observed that exogenous Spd could increase the activities of the enzymes superoxide dismutase (SOD; EC: 1.15.1.1), peroxidase (POD; EC: 1.11.1.7) and catalase (CAT; EC: 1.11.1.6) as well as the expression of their genes in salt-stressed roots, and the effects were inhibited by H 2 O 2 scavengers and polyamine oxidase inhibitors. These results suggested that, by regulating endogenous PAs-mediated H 2 O 2 signaling in roots, Spd could enhance antioxidant enzyme activities and reduce oxidative damage; the main source of H 2 O 2 was polyamine oxidation, which was associated with improved tolerance and root growth recovery of cucumber under salt stress. Copyright © 2018 Elsevier Masson SAS. All rights reserved.

Anti-inflammatory effects of LJP 1586 [Z-3-fluoro-2-(4-methoxybenzyl)allylamine hydrochloride], an amine-based inhibitor of semicarbazide-sensitive amine oxidase activity.

PubMed

O'Rourke, Anne M; Wang, Eric Y; Miller, Andrew; Podar, Erika M; Scheyhing, Kelly; Huang, Li; Kessler, Christina; Gao, Hongfeng; Ton-Nu, Huong-Thu; Macdonald, Mary T; Jones, David S; Linnik, Matthew D

2008-02-01

Semicarbazide-sensitive amine oxidase (SSAO, amine oxidase, copper-containing 3, and vascular adhesion protein-1) is a copper-containing enzyme that catalyzes the oxidative deamination of primary amines to an aldehyde, ammonia, and hydrogen peroxide. SSAO is also involved in leukocyte migration to sites of inflammation, and the enzymatic activity of SSAO is essential to this role. Thus, inhibition of SSAO enzyme activity represents a target for the development of small molecule anti-inflammatory compounds. Here, we have characterized the novel SSAO inhibitor, Z-3-fluoro-2-(4-methoxybenzyl)allylamine hydrochloride (LJP 1586), and assessed its anti-inflammatory activity. LJP 1586 is a potent inhibitor of rodent and human SSAO activity, with IC(50) values between 4 and 43 nM. The selectivity of LJP 1586 was confirmed with a broad panel of receptors and enzymes that included the monoamine oxidases A and B. Oral administration of LJP 1586 resulted in complete inhibition of rat lung SSAO, with an ED(50) between 0.1 and 1 mg/kg, and a pharmacodynamic half-life of greater than 24 h. In a mouse model of inflammatory leukocyte trafficking oral dosing with LJP 1586 resulted in significant dose-dependent inhibition of neutrophil accumulation, with an effect comparable to that of anti-leukocyte function-associated antigen-1 antibody. In a rat model of LPS-induced lung inflammation, administration of 10 mg/kg LJP 1586 resulted in a 55% significant reduction in transmigrated cells recovered by bronchoalveolar lavage. The results demonstrate that a selective, orally active small molecule inhibitor of SSAO is an effective anti-inflammatory compound in vivo and provide further support for SSAO as a therapeutic anti-inflammatory target.

Reactive oxygen species generation mediated by NADPH oxidase and PI3K/Akt pathways contribute to invasion of Streptococcus agalactiae in human endothelial cells.

PubMed

Oliveira, Jessica Silva Santos de; Santos, Gabriela da Silva; Moraes, João Alfredo; Saliba, Alessandra Mattos; Barja-Fidalgo, Thereza Christina; Mattos-Guaraldi, Ana Luíza; Nagao, Prescilla Emy

2018-01-01

BACKGROUND Streptococcus agalactiae can causes sepsis, pneumonia, and meningitis in neonates, the elderly, and immunocompromised patients. Although the virulence properties of S. agalactiae have been partially elucidated, the molecular mechanisms related to reactive oxygen species (ROS) generation in infected human endothelial cells need further investigation. OBJECTIVES This study aimed to evaluate the influence of oxidative stress in human umbilical vein endothelial cells (HUVECs) during S. agalactiae infection. METHODS ROS production during S. agalactiae-HUVEC infection was detected using the probe CM-H2DCFDA. Microfilaments labelled with phalloidin-FITC and p47phox-Alexa 546 conjugated were analysed by immunofluorescence. mRNA levels of p47phox (NADPH oxidase subunit) were assessed using Real Time qRT-PCR. The adherence and intracellular viability of S. agalactiae in HUVECs with or without pre-treatment of DPI, apocynin (NADPH oxidase inhibitors), and LY294002 (PI3K inhibitor) were evaluated by penicillin/gentamicin exclusion. Phosphorylation of p47phox and Akt activation by S. agalactiae were evaluated by immunoblotting analysis. FINDINGS Data showed increased ROS production 15 min after HUVEC infection. Real-Time qRT-PCR and western blotting performed in HUVEC infected with S. agalactiae detected alterations in mRNA levels and activation of p47phox. Pre-treatment of endothelial cells with NADPH oxidase (DPI and apocynin) and PI3K/Akt pathway (LY294002) inhibitors reduced ROS production, bacterial intracellular viability, and generation of actin stress fibres in HUVECs infected with S. agalactiae. CONCLUSIONS ROS generation via the NADPH oxidase pathway contributes to invasion of S. agalactiae in human endothelial cells accompanied by cytoskeletal reorganisation through the PI3K/Akt pathway, which provides novel evidence for the involvement of oxidative stress in S. agalactiae pathogenesis.

Role of VPO1, a newly identified heme-containing peroxidase, in ox-LDL induced endothelial cell apoptosis

PubMed Central

Bai, Yong-Ping; Hu, Chang-Ping; Yuan, Qiong; Peng, Jun; Shi, Rui-Zheng; Yang, Tian-Lun; Cao, Ze-Hong; Li, Yuan-Jian; Cheng, Guangjie; Zhang, Guo-Gang

2013-01-01

Myeloperoxidase (MPO) is an important enzyme involved in the genesis and development of atherosclerosis. Vascular peroxidase 1 (VPO1) is a newly discovered member of the peroxidase family that is mainly expressed in vascular endothelial cells and smooth muscle cells and has structural characteristics and biological activity similar to those of MPO. Our specific aims were to explore the effects of VPO1 on endothelial cell apoptosis induced by oxidized low-density lipoprotein (ox-LDL) and the underlying mechanisms. The results showed that ox-LDL induced endothelial cell apoptosis and the expression of VPO1 in endothelial cells in a concentration- and time-dependent manner concomitant with increased intracellular reactive oxygen species (ROS) and hypochlorous acid (HOCl) generation, and up-regulated protein expression of the NADPH oxidase gp91phox subunit and phosphorylation of p38 MAPK. All these effects of ox-LDL were inhibited by VPO1 gene silencing and NADPH oxidase gp91phox subunit gene silencing or by pretreatment with the NADPH oxidase inhibitor apocynin or diphenyliodonium. The p38 MAPK inhibitor SB203580 or the caspase-3 inhibitor DEVD-CHO significantly inhibited ox-LDL-induced endothelial cell apoptosis, but had no effect on intracellular ROS and HOCl generation or the expression of NADPH oxidase gp91phox subunit or VPO1. Collectively, these findings suggest for the first time that VPO1 plays a critical role in ox-LDL-induced endothelial cell apoptosis and that there is a positive feedback loop between VPO1/HOCl and the now-accepted dogma that the NADPH oxidase/ROS/p38 MAPK/caspase-3 pathway is involved in ox-LDL-induced endothelial cell apoptosis. PMID:21820048

MAOIs and Diet: Is It Necessary to Restrict Tyramine?

MedlinePlus

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Kinetics of intraventricularly injected trace amines and their deuterated isotopomers

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

Durden, D.A.; Nguyen, T.V.; Boulton, A.A.

Intraventricular injection into the rat brain of four trace amines and a catecholamine resulted in rapid exponential loss of the amines in the first 30 minutes after injection. The half-lives were: phenylethylamine 3.8 min, para-tyramine 5.1 min, meta-tyramine 7.4 min and dopamine 8.0 min. Tryptamine showed a biphasic loss with half-lives of 4.7 min (over the 5 to 10 min period) and 14.1 min (10 to 30 min). The half-lives were substantially increased by deuterium labeling at the alpha carbon position: phenylethylamine 4.8 min, para-tyramine 8.8 min, meta-tyramine 14.1 min, dopamine 13.0 min and tryptamine 6.0 min (5 to 10more » min period) and 28.7 min (10 to 20 min). The loss of the amines was reduced by monoamine oxidase inhibition by pargyline hydrochloride and the deuterium isotope effect was abolished. It is noteworthy that the half-life of dopamine was similar to those of the trace amines in this time period and that the trace amine half-lives after i.v. injection was longer than those obtained from measurements of increases of concentrations of endogenous amines after MAOI in vivo and that of dopamine shorter than values calculated from turnover measurements.« less

Novel human D-amino acid oxidase inhibitors stabilize an active-site lid-open conformation

PubMed Central

Terry-Lorenzo, Ryan T.; Chun, Lawrence E.; Brown, Scott P.; Heffernan, Michele L. R.; Fang, Q. Kevin; Orsini, Michael A.; Pollegioni, Loredano; Hardy, Larry W.; Spear, Kerry L.; Large, Thomas H.

2014-01-01

The NMDAR (N-methyl-D-aspartate receptor) is a central regulator of synaptic plasticity and learning and memory. hDAAO (human D-amino acid oxidase) indirectly reduces NMDAR activity by degrading the NMDAR co-agonist D-serine. Since NMDAR hypofunction is thought to be a foundational defect in schizophrenia, hDAAO inhibitors have potential as treatments for schizophrenia and other nervous system disorders. Here, we sought to identify novel chemicals that inhibit hDAAO activity. We used computational tools to design a focused, purchasable library of compounds. After screening this library for hDAAO inhibition, we identified the structurally novel compound, ‘compound 2’ [3-(7-hydroxy-2-oxo-4-phenyl-2H-chromen-6-yl)propanoic acid], which displayed low nM hDAAO inhibitory potency (Ki=7 nM). Although the library was expected to enrich for compounds that were competitive for both D-serine and FAD, compound 2 actually was FAD uncompetitive, much like canonical hDAAO inhibitors such as benzoic acid. Compound 2 and an analog were independently co-crystalized with hDAAO. These compounds stabilized a novel conformation of hDAAO in which the active-site lid was in an open position. These results confirm previous hypotheses regarding active-site lid flexibility of mammalian D-amino acid oxidases and could assist in the design of the next generation of hDAAO inhibitors. PMID:25001371

Rho-kinase inhibitor and nicotinamide adenine dinucleotide phosphate oxidase inhibitor prevent impairment of endothelium-dependent cerebral vasodilation by acute cigarette smoking in rats.

PubMed

Iida, Hiroki; Iida, Mami; Takenaka, Motoyasu; Fukuoka, Naokazu; Dohi, Shuji

2008-06-01

We previously reported that acute cigarette smoking can cause a dysfunction of endothelium-dependent vasodilation in cerebral vessels, and that blocking the angiotensin II (Ang II) type 1 (AT1) receptor with valsartan prevented this impairment. Our aim was to investigate the effects of a Rho-kinase inhibitor (fasudil) and a Nicotinamide Adenine Dinucleotide PHosphate (NADPH) oxidase inhibitor (apocynin) on smoking-induced endothelial dysfunction in cerebral arterioles. In Sprague-Dawley rats, we used a closed cranial window preparation to measure changes in pial vessel diameters following topical acetylcholine (ACh) before smoking. After one-minute smoking, we again examined the arteriolar responses to ACh. Finally, after intravenous fasudil or apocynin pre-treatment we re-examined the vasodilator responses to topical ACh (before and after cigarette smoking). Under control conditions, cerebral arterioles were dose-dependently dilated by topical ACh (10(-6) M and 10(-5) M). One hour after a one-minute smoking (1 mg-nicotine cigarette), 10(-5) M ACh constricted cerebral arterioles. However, one hour after a one-minute smoking, 10(-5) M ACh dilated cerebral pial arteries both in the fasudil pre-treatment and the apocynin pre-treatment groups, responses that were significantly different from those obtained without fasudil or apocynin pre-treatment. Thus, inhibition of Rho-kinase and NADPH oxidase activities may prevent the above smoking-induced impairment of endothelium-dependent vasodilation.

NADPH Oxidase Activation Contributes to Heavy Ion Irradiation–Induced Cell Death

PubMed Central

Wang, Yupei; Liu, Qing; Zhao, Weiping; Zhou, Xin; Miao, Guoying; Sun, Chao

2017-01-01

Increased oxidative stress plays an important role in heavy ion radiation–induced cell death. The mechanism involved in the generation of elevated reactive oxygen species (ROS) is not fully illustrated. Here we show that NADPH oxidase activation is closely related to heavy ion radiation–induced cell death via excessive ROS generation. Cell death and cellular ROS can be greatly reduced in irradiated cancer cells with the preincubation of diphenyleneiodium, an inhibitor of NADPH oxidase. Most of the NADPH oxidase (NOX) family proteins (NOX1, NOX2, NOX3, NOX4, and NOX5) showed increased expression after heavy ion irradiation. Meanwhile, the cytoplasmic subunit p47phox was translocated to the cell membrane and localized with NOX2 to form reactive NADPH oxidase. Our data suggest for the first time that ROS generation, as mediated by NADPH oxidase activation, could be an important contributor to heavy ion irradiation–induced cell death. PMID:28473742

Enzymatic properties of the membrane-bound NADH oxidase system in the aerobic respiratory chain of Bacillus cereus.

PubMed

Kim, Man Suk; Kim, Young Jae

2004-11-30

Membranes prepared from Bacillus cereus KCTC 3674, grown aerobically on a complex medium, oxidized NADH exclusively, whereas deamino-NADH was little oxidized. The respiratory chain-linked NADH oxidase exhibited an apparent K(m) value of approximately 65 microM for NADH. The maximum activity of the NADH oxidase was obtained at about pH 8.5 in the presence of 0.1 M KCl (or NaCl). Respiratory chain inhibitor 2-heptyl-4-hydroxyquinoline-N-oxide (HQNO) inhibited the activity of the NADH oxidase by about 90% at a concentration of 40 microM. Interestingly, rotenone and capsaicin inhibited the activity of the NADH oxidase by about 60% at a concentration of 40 microM and the activity was also highly sensitive to Ag(+).

Inhibition of Human Vascular NADPH Oxidase by Apocynin Derived Oligophenols

PubMed Central

Mora-Pale, Mauricio; Weïwer, Michel; Yu, Jingjing; Linhardt, Robert J.; Dordick, Jonathan S.

2009-01-01

Enzymatic oxidation of apocynin, which may mimic in vivo metabolism, affords a large number of oligomers (apocynin oxidation products, AOP) that inhibit vascular NADPH oxidase. In vitro studies of NADPH oxidase activity were performed to identify active inhibitors, resulting in a trimer hydroxylated quinone (IIIHyQ) that inhibited NADPH oxidase with an IC50 = 31 nM. Apocynin itself possessed minimal inhibitory activity. NADPH oxidase is believed to be inhibited through prevention of the interaction between two NADPH oxidase subunits, p47phox and p22phox. To that end, while apocynin was unable to block the interaction of his-tagged p47phox with a surface immobilized biotinalyted p22phox peptide, the IIIHyQ product strongly interfered with this interaction (apparent IC50 = 1.6 μM). These results provide evidence that peroxidase-catalyzed AOP, which consist of oligomeric phenols and quinones, inhibit critical interactions that are involved in the assembly and activation of human vascular NADPH oxidase. PMID:19523836

High-performance liquid chromatography coupled with post-column dual-bioactivity assay for simultaneous screening of xanthine oxidase inhibitors and free radical scavengers from complex mixture.

PubMed

Li, D Q; Zhao, J; Li, S P

2014-06-06

Xanthine oxidase (XO) can catalyze hypoxanthine and xanthine to generate uric acid and reactive oxygen species (ROS), including superoxide anion radical (O₂(•-)) and hydrogen peroxide. XO inhibitors and free radical scavengers are beneficial to the treatment of gout and many related diseases. In the present study, an on-line high-performance liquid chromatography (HPLC) coupled with post-column dual-bioactivity assay was established and successfully applied to simultaneously screening of XO inhibitors and free radical scavengers from a complex mixture, Oroxylum indicum extract. The integrated system of HPLC separation, bioactivity screening and mass spectrometry identification was proved to be simple and effective for rapid and sensitive screening of individual bioactive compounds in complex mixtures. Copyright © 2014 Elsevier B.V. All rights reserved.

On the use of L-012, a luminol-based chemiluminescent probe, for detecting superoxide and identifying inhibitors of NADPH oxidase: A re-evaluation

PubMed Central

Zielonka, Jacek; Lambeth, J. David; Kalyanaraman, Balaraman

2014-01-01

L-012, a luminol-based chemiluminescent (CL) probe, is widely used in vitro and in vivo to detect NADPH oxidase (Nox)-derived superoxide (O2·−) and identify Nox inhibitors. Yet understanding of the free radical chemistry of L-012 probe is still lacking. We report that peroxidase and H2O2 induce superoxide dismutase (SOD)-sensitive, L-012-derived CL in the presence of oxygen. O2·− alone does not react with L-012 to emit luminescence. Self-generated O2·− during oxidation of L-012 and luminol-analogs artifactually induce CL inhibitable by SOD. These aspects make assays based on luminol analogs less than ideal for specific detection and identification of O2·− and NOX inhibitors. PMID:24080119

Synthesis and evaluation of biaryl derivatives for structural characterization of selective monoamine oxidase B inhibitors toward Parkinson's disease therapy.

PubMed

Yeon, Seul Ki; Choi, Ji Won; Park, Jong-Hyun; Lee, Ye Rim; Kim, Hyeon Jeong; Shin, Su Jeong; Jang, Bo Ko; Kim, Siwon; Bahn, Yong-Sun; Han, Gyoonhee; Lee, Yong Sup; Pae, Ae Nim; Park, Ki Duk

2018-01-01

Benzyloxyphenyl moiety is a common structure of highly potent, selective and reversible inhibitors of monoamine oxidase B (MAO-B), safinamide and sembragiline. We synthesized 4-(benzyloxy)phenyl and biphenyl-4-yl derivatives including halogen substituents on the terminal aryl unit. In addition, we modified the carbon linker between amine group and the biaryl linked unit. Among synthesized compounds, 12c exhibited the most potent and selective MAO-B inhibitory effect (hMAO-B IC 50 : 8.9 nM; >10,000-fold selectivity over MAO-A) as a competitive inhibitor. In addition, 12c showed greater MAO-B inhibitory activity and selectivity compared to well-known MAO-B inhibitors such as selegiline, safinamide and sembragiline. In the MPTP-induced mouse model of Parkinson's disease (PD), 12c significantly protected the tyrosine hydroxylase (TH)-immunopositive DAergic neurons and attenuated the PD-associated behavioral deficits. This study suggests characteristic structures as a MAO-B inhibitor that may provide a good insight for the development of therapeutic agents for PD. Copyright © 2017 Elsevier Ltd. All rights reserved.

SIRT1 inhibits NADPH oxidase activation and protects endothelial function in the rat aorta: implications for vascular aging.

PubMed

Zarzuelo, María José; López-Sepúlveda, Rocío; Sánchez, Manuel; Romero, Miguel; Gómez-Guzmán, Manuel; Ungvary, Zoltan; Pérez-Vizcaíno, Francisco; Jiménez, Rosario; Duarte, Juan

2013-05-01

Vascular aging is characterized by up-regulation of NADPH oxidase, oxidative stress and endothelial dysfunction. Previous studies demonstrate that the activity of the evolutionarily conserved NAD(+)-dependent deacetylase SIRT1 declines with age and that pharmacological activators of SIRT1 confer significant anti-aging cardiovascular effects. To determine whether dysregulation of SIRT1 promotes NADPH oxidase-dependent production of reactive oxygen species (ROS) and impairs endothelial function we assessed the effects of three structurally different inhibitors of SIRT1 (nicotinamide, sirtinol, EX527) in aorta segments isolated from young Wistar rats. Inhibition of SIRT1 induced endothelial dysfunction, as shown by the significantly reduced relaxation to the endothelium-dependent vasodilators acetylcholine and the calcium ionophore A23187. Endothelial dysfunction induced by SIRT1 inhibition was prevented by treatment of the vessels with the NADPH oxidase inhibitor apocynin or superoxide dismutase. Inhibition of SIRT1 significantly increased vascular superoxide production, enhanced NADPH oxidase activity, and mRNA expression of its subunits p22(phox) and NOX4, which were prevented by resveratrol. Peroxisome proliferator-activated receptor-α (PPARα) activation mimicked the effects of resveratrol while PPARα inhibition prevented the effects of this SIRT1 activator. SIRT1 co-precipitated with PPARα and nicotinamide increased the acetylation of the PPARα coactivator PGC-1α, which was suppressed by resveratrol. In conclusion, impaired activity of SIRT1 induces endothelial dysfunction and up-regulates NADPH oxidase-derived ROS production in the vascular wall, mimicking the vascular aging phenotype. Moreover, a new mechanism for controlling endothelial function after SIRT1 activation involves a decreased PGC-1α acetylation and the subsequent PPARα activation, resulting in both decreased NADPH oxidase-driven ROS production and NO inactivation. Copyright © 2013 Elsevier Inc. All rights reserved.

Effects of phenylated compounds of methylglyoxal bis(guanylhydrazone) on diamine oxidase activity from rat small intestine.

PubMed

Balaña-Fouce, R; Pulido, T G; Escudero, D O; Sanz-Sanchez, F

1986-01-01

Two phenylated compounds of methylglyoxal bis(guanylhydrazone), potentially inhibitors of diamine oxidase activity, have been synthesized: phenylglyoxal bis(guanylhydrazone) and diphenylglyoxal bis(guanylhydrazone). Their inhibitory capacity was tested: while PGBG was able to reduce the enzyme activity by 50% at 1.3 microM, DPGBG was only able to reduce diamine oxidase activity by less than 2% at a concentration 1000-fold higher. The inhibition of PGBG was non-competitive and the Ki calculated by a Dixon plot was estimated as 1.7 microM.

Discovery of d-amino acid oxidase inhibitors based on virtual screening against the lid-open enzyme conformation.

PubMed

Szilágyi, Bence; Skok, Žiga; Rácz, Anita; Frlan, Rok; Ferenczy, György G; Ilaš, Janez; Keserű, György M

2018-06-01

d-Amino acid oxidase (DAAO) inhibitors are typically small polar compounds with often suboptimal pharmacokinetic properties. Features of the native binding site limit the operational freedom of further medicinal chemistry efforts. We therefore initiated a structure based virtual screening campaign based on the X-ray structures of DAAO complexes where larger ligands shifted the loop (lid opening) covering the native binding site. The virtual screening of our in-house collection followed by the in vitro test of the best ranked compounds led to the identification of a new scaffold with micromolar IC 50 . Subsequent SAR explorations enabled us to identify submicromolar inhibitors. Docking studies supported by in vitro activity measurements suggest that compounds bind to the active site with a salt-bridge characteristic to DAAO inhibitor binding. In addition, displacement of and interaction with the loop covering the active site contributes significantly to the activity of the most potent compounds. Copyright © 2018 Elsevier Ltd. All rights reserved.

Inhibition of in vivo histamine metabolism in rats by foodborne and pharmacologic inhibitors of diamine oxidase, histamine N-methyltransferase, and monoamine oxidase

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

Hui, J.Y.; Taylor, S.L.

When (/sup 14/C)histamine was administered orally to rats, an average of 80% of the administered radioactivity was recovered in the urine at the end of 24 hr. About 10% of the total dose was excreted via the feces. Analysis of 4-hr urine samples found imidazoleacetic acid to be the predominant metabolite (60.6%), with N tau-methylimidazoleacetic acid (8.6%), N tau-methylhistamine (7.3%), and N-acetylhistamine (4.5%) to be the minor metabolites. Histamine metabolism was inhibited by simultaneous oral administration of aminoguanidine, isoniazid, quinacrine, cadaverine, putrescine, tyramine, and beta-phenylethylamine. The administration of inhibitors resulted in an increased amount of unmetabolized histamine and a decreasedmore » amount of metabolites reaching the urine. Pharmacologic inhibitors were found to be more potent and have a longer duration of action than foodborne ones. The inhibitors could potentiate food poisoning caused by histamine by inhibiting its metabolism.« less

2-acetylphenol analogs as potent reversible monoamine oxidase inhibitors.

PubMed

Legoabe, Lesetja J; Petzer, Anél; Petzer, Jacobus P

2015-01-01

Based on a previous report that substituted 2-acetylphenols may be promising leads for the design of novel monoamine oxidase (MAO) inhibitors, a series of C5-substituted 2-acetylphenol analogs (15) and related compounds (two) were synthesized and evaluated as inhibitors of human MAO-A and MAO-B. Generally, the study compounds exhibited inhibitory activities against both MAO-A and MAO-B, with selectivity for the B isoform. Among the compounds evaluated, seven compounds exhibited IC50 values <0.01 µM for MAO-B inhibition, with the most selective compound being 17,000-fold selective for MAO-B over the MAO-A isoform. Analyses of the structure-activity relationships for MAO inhibition show that substitution on the C5 position of the 2-acetylphenol moiety is a requirement for MAO-B inhibition, and the benzyloxy substituent is particularly favorable in this regard. This study concludes that C5-substituted 2-acetylphenol analogs are potent and selective MAO-B inhibitors, appropriate for the design of therapies for neurodegenerative disorders such as Parkinson's disease.

Monoamine oxidase inhibitory activity in tobacco particulate matter: Are harman and norharman the only physiologically relevant inhibitors?

PubMed

Truman, Penelope; Grounds, Peter; Brennan, Katharine A

2017-03-01

Monoamine oxidase inhibition is significant in smokers, but it is still unclear how the inhibition that is seen in the brains and bodies of smokers is brought about. Our aim was to test the contribution of the harman and norharman in tobacco smoke to MAO-A inhibition from tobacco smoke preparations, as part of a re-examination of harman and norharman as the cause of the inhibition of MAO-A inhibition in the brain. Tobacco smoke particulate matter and cigarette smoke particulate matter were prepared and the amounts of harman and norharman measured. The results were compared with the total monoamine oxidase-A inhibitory activity. At a nicotine concentration of 0.6μM (a "physiological" concentration in blood) the total monoamine oxidase-A inhibitory activity measured in these samples was sufficient to inhibit the enzyme by approximately 10%. Of this inhibitory activity, only a small proportion of the total was found to be due to harman and norharman. These results show that harman and norharman provide only a moderate contribution to the total monoamine oxidase-A inhibitory activity of tobacco smoke, perhaps under 10%. This suggests that other inhibitors (either known or unknown) may be more significant contributors to total inhibitory activity than has yet been established, and deserve closer examination. Copyright © 2017 Elsevier B.V. All rights reserved.

Monoamine oxidase A inhibitor occupancy during treatment of major depressive episodes with moclobemide or St. John's wort: an [11C]-harmine PET study.

PubMed

Sacher, Julia; Houle, Sylvain; Parkes, Jun; Rusjan, Pablo; Sagrati, Sandra; Wilson, Alan A; Meyer, Jeffrey H

2011-11-01

Monoamine oxidase A (MAO-A) inhibitor antidepressants raise levels of multiple monoamines, whereas the selective serotonin reuptake inhibitors (SSRIs) only raise extracellular serotonin. Despite this advantage of MAO-A inhibitors, there is much less frequent development of MAO inhibitors compared with SSRIs. We sought to measure brain MAO-A occupancy after 6 weeks of treatment in depressed patients with a clinically effective dose of a selective MAO-A inhibitor and measure MAO-A occupancy after repeated administration of St. John's wort, an herb purported to have MAO-A inhibitor properties. Participants underwent 2 [(11)C]-harmine positron emission tomography scans. Healthy controls completed a test-retest condition, and depressed patients were scanned before and after repeated administration of moclobemide or St. John's wort for 6 weeks at the assigned dose. We measured MAO-A VT, an index of MAO-A density, in the prefrontal, anterior cingulate and anterior temporal cortices, putamen, thalamus, midbrain and hippocampus. We included 23 participants (10 controls and 13 patients with major depressive disorder [MDD]) in our study. Monoamine oxidase A VT decreased significantly throughout all regions after moclobemide treatment in patients with MDD compared with controls (repeated-measures analysis of variance, F1,15 = 71.08-130.06, p < 0.001 for all regions, mean occupancy 74% [standard deviation 6%]). Treatment with St. John's wort did not significantly alter MAO-A VT. The occupancy estimates are limited by the sample size of each treatment group; hence, our estimate for the overall moclobemide occupancy of 74% has a 95% confidence interval of 70%-78%, and we can estimate with 95% certainty that the occupancy of St. John's wort is less than 5%. For new MAO-A inhibitors, about 74% occupancy at steady-state dosing is desirable. Consistent with this, St. John's wort should not be classified as an MAO-A inhibitor. The magnitude of MAO-A blockade during moclobemide treatment exceeds the elevation of MAO-A binding during illness by at least 30%, suggesting that the treatment effect should exceed the disease effect when designing selective antidepressants for this target. © 2011 Canadian Medical Association

9-Benzoyl 9-deazaguanines as potent xanthine oxidase inhibitors.

PubMed

Rodrigues, Marili V N; Barbosa, Alexandre F; da Silva, Júlia F; dos Santos, Deborah A; Vanzolini, Kenia L; de Moraes, Marcela C; Corrêa, Arlene G; Cass, Quezia B

2016-01-15

A novel potent xanthine oxidase inhibitor, 3-nitrobenzoyl 9-deazaguanine (LSPN451), was selected from a series of 10 synthetic derivatives. The enzymatic assays were carried out using an on-flow bidimensional liquid chromatography (2D LC) system, which allowed the screening¸ the measurement of the kinetic inhibition constant and the characterization of the inhibition mode. This compound showed a non-competitive inhibition mechanism with more affinity for the enzyme-substrate complex than for the free enzyme, and inhibition constant of 55.1±9.80 nM, about thirty times more potent than allopurinol. Further details of synthesis and enzymatic studies are presented herein. Copyright © 2015 Elsevier Ltd. All rights reserved.

Cytological evaluation of the effect of azoxystrobin and alternative oxidase inhibitors in Botrytis cinerea.

PubMed

Inoue, Kanako; Tsurumi, Tomohiro; Ishii, Hideo; Park, Pyoyun; Ikeda, Kenichi

2012-01-01

Azoxystrobin (AZ), a strobilurin-derived fungicide, is known to inhibit mitochondrial respiration in fungi by blocking the electron transport chain in the inner mitochondrial membrane. Germination was strongly inhibited when Botrytis cinerea spore suspension was treated with AZ and the alternative oxidase (AOX) inhibitors, salicylhydroxamic acid (SHAM) and n-propyl gallate. However, chemical death indicators trypan blue and propidium iodide showed that those spores were still alive. When the spore suspension in the AZ and SHAM solution was replaced with distilled water, the germination rate almost recovered, at least during the first 2 days of incubation with AZ and SHAM solution. No morphological alteration was detected in the cells treated with AZ and SHAM, especially in mitochondria, using transmission electron microscopy. Therefore, simultaneous application of AZ and AOX inhibitors has a fungistatic, rather than a fungicidal, action. © 2011 Federation of European Microbiological Societies. Published by Blackwell Publishing Ltd. All rights reserved.

New isoxazolidinone and 3,4-dehydro-β-proline derivatives as antibacterial agents and MAO-inhibitors: A complex balance between two activities.

PubMed

Ferrazzano, Lucia; Viola, Angelo; Lonati, Elena; Bulbarelli, Alessandra; Musumeci, Rosario; Cocuzza, Clementina; Lombardo, Marco; Tolomelli, Alessandra

2016-11-29

Among the different classes of antibiotics, oxazolidinone derivatives represent important drugs, since their unique mechanism of action overcomes commonly diffused multidrug-resistant bacteria. Anyway, the structural similarity of these molecules to monoamino oxidase (MAO) inhibitors, like toloxatone and blefoxatone, induces in many cases loss of selectivity as a major concern. A small library of compounds based on isoxazolidinone and dehydro-β-proline scaffold was designed with the aim to obtain antibacterial agents, evaluating at the same time the potential effects of structural features on MAO inhibitory behaviour. The structural modification introduced in the backbone, starting from Linezolid model, lead to a significant loss in antibiotic activity, while a promising inhibitory effect could be observed on monoamino oxidases. These interesting results are also in agreement with docking experiments suggesting a good binding pose of the synthesized compounds into the pocket of the oxidase enzymes, in particular of MAO-B. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

The dual actions of morin (3,5,7,2',4'-pentahydroxyflavone) as a hypouricemic agent: uricosuric effect and xanthine oxidase inhibitory activity.

PubMed

Yu, Zhifeng; Fong, Wing Ping; Cheng, Christopher H K

2006-01-01

Hyperuricemia is associated with a number of pathological conditions such as gout. Lowering of elevated uric acid level in the blood could be achieved by xanthine oxidase inhibitors and inhibitors of renal urate reabsorption. Some natural compounds isolated from herbs used in traditional Chinese medicine have been previously demonstrated to possess xanthine oxidase inhibitory activities. In the present investigation, morin (3,5,7,2',4'-pentahydroxyflavone), which occurs in the twigs of Morus alba L. documented in traditional Chinese medicinal literature to treat conditions akin to gout, was demonstrated to exert potent inhibitory action on urate uptake in rat renal brush-border membrane vesicles, indicating that this compound acts on the kidney to inhibit urate reabsorption. Lineweaver-Burk transformation of the inhibition kinetics data demonstrated that the inhibition of urate uptake was of a competitive type, with a K(i) value of 17.4 microM. In addition, morin was also demonstrated to be an inhibitor of xanthine oxidase. Lineweaver-Burk analysis of the enzyme kinetics indicated that the mode of inhibition was of a mixed type, with K(i) and K(ies) values being 7.9 and 35.1 microM, respectively. Using an oxonate-induced hyperuricemic rat model, morin was indeed shown to exhibit an in vivo uricosuric action, which could explain, in part at least, the observed hypouricemic effect of morin in these rats. The potential application of this compound in the treatment of conditions associated with hyperuricemia was discussed.

Impact of socio-demographic factors on the mitigating actions for climate change: a path analysis with mediating effects of attitudinal variables.

PubMed

Masud, Muhammad Mehedi; Akhatr, Rulia; Nasrin, Shamima; Adamu, Ibrahim Mohammed

2017-12-01

Socio-demographic factors play a significant role in increasing the individual's climate change awareness and in setting a favorable individual attitude towards its mitigation. To better understand how the adversative effects of climate change can be mitigated, this study attempts to investigate the impact of socio-demographic factors on the mitigating actions of the individuals (MAOI) on climate change. Qualitative data were collected from a face-to-face survey of 360 respondents in the Kuala Lumpur region of Malaysia through a close-ended questionnaire. Analysis was conducted on the mediating effects of attitudinal variables through the path model by using the SEM. Findings indicate that the socio-demographic factors such as gender, age, education, income, and ethnicity can greatly influence the individual's awareness, attitude, risk perception, and knowledge of climate change issues. The results drawn from this study also revealed that the attitudinal factors act as a mediating effect between the socio-demographic factors and the MAOI, thereby, indicating that both the socio-demographic factors and the attitudinal factors have significant effects on the MAOI towards climate change. The outcome of this study can help policy makers and other private organizations to decide on the appropriate actions to take in managing climate change effects. These actions which encompass improving basic climate change education and making the public more aware of the local dimensions of climate change are important for harnessing public engagement and support that can also stimulate climate change awareness and promote mitigating actions to n protect the environment from the impact of climate change.

Interactions of Monoamine Oxidases with the Antiepileptic Drug Zonisamide: Specificity of Inhibition and Structure of the Human Monoamine oxidase B Complex

PubMed Central

Binda, Claudia; Aldeco, Milagros; Mattevi, Andrea; Edmondson, Dale E.

2010-01-01

The binding of zonisamide to purified, recombinant monoamine oxidases (MAOs) has been investigated. It is a competitive inhibitor of human MAO B (Ki = 3.1 ± 0.3 μM), of rat MAO B (Ki = 2.9 ± 0.5 μM), and of zebrafish MAO (Ki = 30.8 ± 5.3 μM). No inhibition is observed with purified human or rat MAO A. The 1.8 Å structure of the MAO B complex demonstrates that it binds within the substrate cavity. PMID:21175212

A Conserved Steroid Binding Site in Cytochrome c Oxidase

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

Qin, Ling; Mills, Denise A.; Buhrow, Leann

2010-09-02

Micromolar concentrations of the bile salt deoxycholate are shown to rescue the activity of an inactive mutant, E101A, in the K proton pathway of Rhodobacter sphaeroides cytochrome c oxidase. A crystal structure of the wild-type enzyme reveals, as predicted, deoxycholate bound with its carboxyl group at the entrance of the K path. Since cholate is a known potent inhibitor of bovine oxidase and is seen in a similar position in the bovine structure, the crystallographically defined, conserved steroid binding site could reveal a regulatory site for steroids or structurally related molecules that act on the essential K proton path.

NADPH oxidase inhibitor, diphenyleneiodonium prevents necroptosis in HK-2 cells.

PubMed

Dong, Wei; Li, Zhilian; Chen, Yuanhan; Zhang, Li; Ye, Zhiming; Liang, Huaban; Li, Ruizhao; Xu, Lixia; Zhang, Bin; Liu, Shuangxin; Wang, Weidong; Li, Chunling; Luo, Jialun; Shi, Wei; Liang, Xinling

2017-09-01

The aim of the present study was to investigate the protective effect of the NADPH oxidase inhibitor, diphenyleneiodonium (DPI) against necroptosis in renal tubular epithelial cells. A necroptosis model of HK-2 cells was established using tumor necrosis factor-α, benzyloxycarbonyl-Val-Ala-Asp-fluoromethylketone and antimycin A (collectively termed TZA), as in our previous research. The necroptosis inhibitor, necrostatin-1 (Nec-1) or the NADPH oxidase inhibitor, DPI were administered to the necroptosis model. Production of reactive oxygen species (ROS) was detected by dichlorodihydrofluorescein diacetate in the different groups, and the manner of cell death was identified by flow cytometry. Western blot analysis was used to determine the levels of phosphorylation of receptor-interacting protein kinase 3 (RIP-3) and mixed lineage kinase domain-like (MLKL), which are essential to necroptosis. The results revealed that TZA increased the percentages of propidium iodide-positive HK-2 cells from 1.22±0.69 to 8.98±0.73% (P<0.001), and augmented the phosphorylation of RIP-3 and MLKL. ROS levels were increased in the TZA group compared with the control group (27.74±1.60×10 4 vs. 18.51±1.10×10 4 , respectively; P<0.001), and could be inhibited by Nec-1 (TZA + Nec-1 group, 22.90±2.22×10 4 vs. TZA group, 27.74±1.60×10 4 ; P=0.01). DPI decreased ROS production (TZA + DPI group, 22.13±1.86×10 4 vs. TZA group, 27.74±1.60×10 4 ; P<0.001) and also reduced the proportions of necrosis in the necroptosis model (TZA + DPI group, 4.40±1.51% vs. TZA group, 8.98±0.73%; P<0.001). Phosphorylated RIP-3 and MLKL were also decreased by DPI treatment. The results indicate that ROS production increases in HK-2 cells undergoing necroptosis, and that the NADPH oxidase inhibitor, DPI may protect HK-2 cells from necroptosis via inhibition of ROS production.

Lesinurad for the treatment of hyperuricaemia in people with gout.

PubMed

Robinson, Philip C; Dalbeth, Nicola

2017-12-01

Gout is a common form of inflammatory arthritis caused by deposition of monosodium urate crystals. The central strategy for effective long-term management of gout is serum urate lowering. Current urate-lowering drugs include both xanthine oxidase inhibitors and uricosuric agents. Lesinurad is a URAT1 inhibitor that selectively inhibits urate rebsorption at the proximal renal tubule. Lesinurad 200mg daily in combination with a xanthine oxidase is approved for urate-lowering therapy in patients with gout. Areas covered: The published literature was searched using Pubmed and additional information was obtained from publically available regulatory documents. Pre-clinical data and clinical trials of lesinurad are described. Serum urate-lowering efficacy and effects on other clinical endpoints are discussed. Adverse event data, focusing on renal safety are also presented. Expert opinion: Lesinurad is an effective urate-lowering drug that has a generally acceptable safety profile when used at 200mg daily dosing in combination with a xanthine oxidase inhibitor. The recent approval of fixed dose combination pills of lesinurad with allopurinol is an important step in improving adherence and reducing risk of renal adverse events. It remains to be seen if this therapy will provide additional benefit for gout management above improved use of widely available generic therapies.

Glutamate release from activated microglia requires the oxidative burst and lipid peroxidation.

PubMed

Barger, Steven W; Goodwin, Mary E; Porter, Mandy M; Beggs, Marjorie L

2007-06-01

When activated by proinflammatory stimuli, microglia release substantial levels of glutamate, and mounting evidence suggests this contributes to neuronal damage during neuroinflammation. Prior studies indicated a role for the Xc exchange system, an amino acid transporter that antiports glutamate for cystine. Because cystine is used for synthesis of glutathione (GSH) synthesis, we hypothesized that glutamate release is an indirect consequence of GSH depletion by the respiratory burst, which produces superoxide from NADPH oxidase. Microglial glutamate release triggered by lipopolysaccharide was blocked by diphenylene iodonium chloride and apocynin, inhibitors of NADPH oxidase. This glutamate release was also blocked by vitamin E and elicited by lipid peroxidation products 4-hydroxynonenal and acrolein, suggesting that lipid peroxidation makes crucial demands on GSH. Although NADPH oxidase inhibitors also suppressed nitrite accumulation, vitamin E did not; moreover, glutamate release was largely unaffected by nitric oxide donors, inhibitors of nitric oxide synthase, or changes in gene expression. These findings indicate that a considerable degree of the neurodegenerative consequences of neuroinflammation may result from conversion of oxidative stress to excitotoxic stress. This phenomenon entails a biochemical chain of events initiated by a programmed oxidative stress and resultant mass-action amino acid transport. Indeed, some of the neuroprotective effects of antioxidants may be due to interference with these events rather than direct protection against neuronal oxidation.

The hemibiotrophic cacao pathogen Moniliophthora perniciosa depends on a mitochondrial alternative oxidase for biotrophic development

PubMed Central

Thomazella, Daniela P T; Teixeira, Paulo José P L; Oliveira, Halley C; Saviani, Elzira E; Rincones, Johana; Toni, Isabella M; Reis, Osvaldo; Garcia, Odalys; Meinhardt, Lyndel W; Salgado, Ione; Pereira, Gonçalo A G

2012-01-01

The tropical pathogen Moniliophthora perniciosa causes witches’ broom disease in cacao. As a hemibiotrophic fungus, it initially colonizes the living host tissues (biotrophic phase), and later grows over the dead plant (necrotrophic phase). Little is known about the mechanisms that promote these distinct fungal phases or mediate the transition between them. An alternative oxidase gene (Mp-aox) was identified in the M. perniciosa genome and its expression was analyzed througout the fungal life cycle. In addition, the effects of inhibitors of the cytochrome-dependent respiratory chain (CRC) and alternative oxidase (AOX) were evaluated on the in vitro development of M. perniciosa. Larger numbers of Mp-aox transcripts were observed in the biotrophic hyphae, which accordingly showed elevated sensitivity to AOX inhibitors. More importantly, the inhibition of CRC prevented the transition from the biotrophic to the necrotrophic phase, and the combined use of a CRC and AOX inhibitor completely halted fungal growth. On the basis of these results, a novel mechanism is presented in which AOX plays a role in the biotrophic development of M. perniciosa and regulates the transition to its necrotrophic stage. Strikingly, this model correlates well with the infection strategy of animal pathogens, particularly Trypanosoma brucei, which uses AOX as a strategy for pathogenicity. PMID:22443281

Antidepressant-like effects of the xanthine oxidase enzyme inhibitor allopurinol in rats. A comparison with fluoxetine.

PubMed

Gürbüz Özgür, Börte; Aksu, Hatice; Birincioğlu, Mustafa; Dost, Turhan

2015-11-01

Allopurinol is a xanthine oxidase enzyme inhibitor that is widely used for the treatment of hyperuricemia and gout. The activity of tryptophan 2,3-dioxygenase, which metabolizes tryptophan (TRP), is decreased by xanthine oxidase inhibitors, causing TRP levels in the body to be increased. Increases in TRP levels in the brain might have antidepressant effects. The purpose of this study is to evaluate the antidepressant effects of allopurinol compared to those of fluoxetine, which is a proven antidepressant. Thirty-two Wistar albino male rats were divided into four groups (control, 10mg/kg fluoxetine, 50mg/kg allopurinol, 50mg/kg allopurinol+10 mg/kg fluoxetine; n=8 per group), and forced swimming tests were performed before and after 14days of drug administration. Serotonin, 5-hydroxyindolacetic acid and uric acid levels were measured in blood samples after the final treatment. When allopurinol and fluoxetine were administered separately, a decrease in the duration of immobility and an increased duration of swimming were observed in the forced swimming test. The results showed similar antidepressant efficacies between allopurinol and fluoxetine. However, we found no statistically significant difference in the antidepressant effect of the combined therapy versus single drug therapy. Copyright © 2015 Elsevier Inc. All rights reserved.

Photoaffinity labeling of protoporphyrinogen oxidase, the molecular target of diphenylether-type herbicides.

PubMed

Camadro, J M; Matringe, M; Thome, F; Brouillet, N; Mornet, R; Labbe, P

1995-05-01

Diphenylether-type herbicides are extremely potent inhibitors of protoporphyrinogen oxidase, a membrane-bound enzyme involved in the heme and chlorophyll biosynthesis pathways. Tritiated acifluorfen and a diazoketone derivative of tritiated acifluorfen were specifically bound to a single class of high-affinity binding sites on yeast mitochondrial membranes with apparent dissociation constants of 7 nM and 12.5 nM, respectively. The maximum density of specific binding sites, determined by Scatchard analysis, was 3 pmol.mg-1 protein. Protoporphyrinogen oxidase specific activity was estimated to be 2500 nmol protoporphyrinogen oxidized h-1.mol-1 enzyme. The diazoketone derivative of tritiated acifluorfen was used to specifically photolabel yeast protoporphyrinogen oxidase. The specifically labeled polypeptide in wild-type mitochondrial membranes had an apparent molecular mass of 55 kDa, identical to the molecular mass of the purified enzyme. This photolabeled polypeptide was not detected in a protoporphyrinogen-oxidase-deficient yeast strain, but the membranes contained an equivalent amount of inactive immunoreactive protoporphyrinogen oxidase protein.

Identification in Marinomonas mediterranea of a novel quinoprotein with glycine oxidase activity.

PubMed

Campillo-Brocal, Jonatan Cristian; Lucas-Elio, Patricia; Sanchez-Amat, Antonio

2013-08-01

A novel enzyme with lysine-epsilon oxidase activity was previously described in the marine bacterium Marinomonas mediterranea. This enzyme differs from other l-amino acid oxidases in not being a flavoprotein but containing a quinone cofactor. It is encoded by an operon with two genes lodA and lodB. The first one codes for the oxidase, while the second one encodes a protein required for the expression of the former. Genome sequencing of M. mediterranea has revealed that it contains two additional operons encoding proteins with sequence similarity to LodA. In this study, it is shown that the product of one of such genes, Marme_1655, encodes a protein with glycine oxidase activity. This activity shows important differences in terms of substrate range and sensitivity to inhibitors to other glycine oxidases previously described which are flavoproteins synthesized by Bacillus. The results presented in this study indicate that the products of the genes with different degrees of similarity to lodA detected in bacterial genomes could constitute a reservoir of different oxidases. © 2013 The Authors. Microbiology Open published by John Wiley & Sons Ltd.

NADPH Oxidase versus Mitochondria-Derived ROS in Glucose-Induced Apoptosis of Pericytes in Early Diabetic Retinopathy

PubMed Central

Mustapha, Nik M.; Tarr, Joanna M.; Kohner, Eva M.; Chibber, Rakesh

2010-01-01

Objectives. Using apocynin (inhibitor of NADPH oxidase), and Mitoquinol 10 nitrate (MitoQ; mitochondrial-targeted antioxidant), we addressed the importance of mitochondria versus NADPH oxidase-derived ROS in glucose-induced apoptosis of pericytes. Methods. NADPH oxidase was localised using Western blot analysis and cytochrome C reduction assay. Apoptosis was detected by measuring caspase-3 activity. Intracellular glucose concentration, ROS formation and Nε-(carboxymethyl) lysine (CML) content were measured using Amplex Red assay kit, dihydroethidium (DHE), and competitive immunoabsorbant enzyme-linked assay (ELISA), respectively. Results. NADPH oxidase was localised in the cytoplasm of pericytes suggesting ROS production within intracellular compartments. High glucose (25 mM) significantly increased apoptosis, intracellular glucose concentration, and CML content. Apoptosis was associated with increased gp91phox expression, activity of NADPH oxidase, and intracellular ROS production. Apocynin and not MitoQ significantly blunted the generation of ROS, formation of intracellular CML and apoptosis. Conclusions. NADPH oxidase and not mitochondria-derived ROS is responsible for the accelerated apoptosis of pericytes in diabetic retinopathy. PMID:20652059

Nox4 NADPH oxidase mediates oxidative stress and apoptosis caused by TNF-α in cerebral vascular endothelial cells

PubMed Central

Basuroy, Shyamali; Bhattacharya, Sujoy; Leffler, Charles W.; Parfenova, Helena

2009-01-01

Inflammatory brain disease may damage cerebral vascular endothelium leading to cerebral blood flow dysregulation. The proinflammatory cytokine TNF-α causes oxidative stress and apoptosis in cerebral microvascular endothelial cells (CMVEC) from newborn pigs. We investigated contribution of major cellular sources of reactive oxygen species to endothelial inflammatory response. Nitric oxide synthase and xanthine oxidase inhibitors (Nω-nitro-l-arginine and allopurinol) had no effect, while mitochondrial electron transport inhibitors (CCCP, 2-thenoyltrifluoroacetone, and rotenone) attenuated TNF-α-induced superoxide (O2•−) and apoptosis. NADPH oxidase inhibitors (diphenylene iodonium and apocynin) greatly reduced TNF-α-evoked O2•− generation and apoptosis. TNF-α rapidly increased NADPH oxidase activity in CMVEC. Nox4, the cell-specific catalytic subunit of NADPH oxidase, is highly expressed in CMVEC, contributes to basal O2•− production, and accounts for a burst of oxidative stress in response to TNF-α. Nox4 small interfering RNA, but not Nox2, knockdown prevented oxidative stress and apoptosis caused by TNF-α in CMVEC. Nox4 is colocalized with HO-2, the constitutive isoform of heme oxygenase (HO), which is critical for endothelial protection against TNF-α toxicity. The products of HO activity, bilirubin and carbon monoxide (CO, as a CO-releasing molecule, CORM-A1), inhibited Nox4-generated O2•− and apoptosis caused by TNF-α stimulation. We conclude that Nox4 is the primary source of inflammation- and TNF-α-induced oxidative stress leading to apoptosis in brain endothelial cells. The ability of CO and bilirubin to combat TNF-α-induced oxidative stress by inhibiting Nox4 activity and/or by O2•− scavenging, taken together with close intracellular compartmentalization of HO-2 and Nox4 in cerebral vascular endothelium, may contribute to HO-2 cytoprotection against inflammatory cerebrovascular disease. PMID:19118162

Sildenafil Promotes eNOS Activation and Inhibits NADPH Oxidase in the Transgenic Sickle Cell Mouse Penis

PubMed Central

Musicki, Biljana; Bivalacqua, Trinity J.; Champion, Hunter C.; Burnett, Arthur L.

2014-01-01

Introduction Sickle cell disease (SCD)-associated vasculopathy in the penis is characterized by aberrant nitric oxide and phosphodiesterase (PDE) 5 signaling, and by increased oxidative stress. Preliminary clinical trials show that continuous treatment with PDE5 inhibitor sildenafil unassociated with sexual activity decreases priapic activity in patients with SCD. However, the mechanism of its vasculoprotective effect in the penis remains unclear. Aims We evaluated whether continuous administration of PDE5 inhibitor sildenafil promotes eNOS function at posttranslational levels and decreases superoxide-producing enzyme NADPH oxidase activity in the sickle cell mouse penis. Methods SCD transgenic mice were used as an animal model of SCD. WT mice served as controls. Mice received treatment with the PDE5 inhibitor sildenafil (100 mg/kg/day) or vehicle for 3 weeks. eNOS phosphorylation on Ser-1177 (positive regulatory site), eNOS interactions with heat-shock protein 90 (HSP90) (positive regulator), phosphorylated AKT (upstream mediator of eNOS phosphorylation on Ser-1177), an NADPH oxidase catalytic subunit gp91(phox), and a marker of oxidative stress (4-hydroxy-2-nonenal [HNE]) were measured by Western blot. Main Outcome Measures Effect of continuous sildenafil treatment on eNOS posttranslational activation, NADPH oxidase catalytic subunit, and oxidative stress in the penis of the sickle cell mouse. Results Continuous treatment with sildenafil reversed (P < 0.05) the abnormalities in protein expressions of P-eNOS (Ser-1177), eNOS/HSP90 interaction, P-AKT, protein expression of gp91(phox), and 4-HNE, in the sickle cell mouse penis. Sildenafil treatment of WT mice did not affect any of these parameters. Conclusion Our findings that sildenafil enhances eNOS activation and inhibits NADPH oxidase function in the sickle cell mouse penis offers a vasculoprotective molecular basis for the therapeutic effect of sildenafil in the penis in association with SCD. PMID:24251665

Sildenafil promotes eNOS activation and inhibits NADPH oxidase in the transgenic sickle cell mouse penis.

PubMed

Musicki, Biljana; Bivalacqua, Trinity J; Champion, Hunter C; Burnett, Arthur L

2014-02-01

Sickle cell disease (SCD)-associated vasculopathy in the penis is characterized by aberrant nitric oxide and phosphodiesterase (PDE) 5 signaling, and by increased oxidative stress. Preliminary clinical trials show that continuous treatment with PDE5 inhibitor sildenafil unassociated with sexual activity decreases priapic activity in patients with SCD. However, the mechanism of its vasculoprotective effect in the penis remains unclear. We evaluated whether continuous administration of PDE5 inhibitor sildenafil promotes eNOS function at posttranslational levels and decreases superoxide-producing enzyme NADPH oxidase activity in the sickle cell mouse penis. SCD transgenic mice were used as an animal model of SCD. WT mice served as controls. Mice received treatment with the PDE5 inhibitor sildenafil (100 mg/kg/day) or vehicle for 3 weeks. eNOS phosphorylation on Ser-1177 (positive regulatory site), eNOS interactions with heat-shock protein 90 (HSP90) (positive regulator), phosphorylated AKT (upstream mediator of eNOS phosphorylation on Ser-1177), an NADPH oxidase catalytic subunit gp91(phox), and a marker of oxidative stress (4-hydroxy-2-nonenal [HNE]) were measured by Western blot. Effect of continuous sildenafil treatment on eNOS posttranslational activation, NADPH oxidase catalytic subunit, and oxidative stress in the penis of the sickle cell mouse. Continuous treatment with sildenafil reversed (P < 0.05) the abnormalities in protein expressions of P-eNOS (Ser-1177), eNOS/HSP90 interaction, P-AKT, protein expression of gp91(phox), and 4-HNE, in the sickle cell mouse penis. Sildenafil treatment of WT mice did not affect any of these parameters. Our findings that sildenafil enhances eNOS activation and inhibits NADPH oxidase function in the sickle cell mouse penis offers a vasculoprotective molecular basis for the therapeutic effect of sildenafil in the penis in association with SCD. © 2013 International Society for Sexual Medicine.

Reactive oxygen species generation mediated by NADPH oxidase and PI3K/Akt pathways contribute to invasion of Streptococcus agalactiae in human endothelial cells

PubMed Central

de Oliveira, Jessica Silva Santos; Santos, Gabriela da Silva; Moraes, João Alfredo; Saliba, Alessandra Mattos; Barja-Fidalgo, Thereza Christina; Mattos-Guaraldi, Ana Luíza; Nagao, Prescilla Emy

2018-01-01

BACKGROUND Streptococcus agalactiae can causes sepsis, pneumonia, and meningitis in neonates, the elderly, and immunocompromised patients. Although the virulence properties of S. agalactiae have been partially elucidated, the molecular mechanisms related to reactive oxygen species (ROS) generation in infected human endothelial cells need further investigation. OBJECTIVES This study aimed to evaluate the influence of oxidative stress in human umbilical vein endothelial cells (HUVECs) during S. agalactiae infection. METHODS ROS production during S. agalactiae-HUVEC infection was detected using the probe CM-H2DCFDA. Microfilaments labelled with phalloidin-FITC and p47phox-Alexa 546 conjugated were analysed by immunofluorescence. mRNA levels of p47phox (NADPH oxidase subunit) were assessed using Real Time qRT-PCR. The adherence and intracellular viability of S. agalactiae in HUVECs with or without pre-treatment of DPI, apocynin (NADPH oxidase inhibitors), and LY294002 (PI3K inhibitor) were evaluated by penicillin/gentamicin exclusion. Phosphorylation of p47phox and Akt activation by S. agalactiae were evaluated by immunoblotting analysis. FINDINGS Data showed increased ROS production 15 min after HUVEC infection. Real-Time qRT-PCR and western blotting performed in HUVEC infected with S. agalactiae detected alterations in mRNA levels and activation of p47phox. Pre-treatment of endothelial cells with NADPH oxidase (DPI and apocynin) and PI3K/Akt pathway (LY294002) inhibitors reduced ROS production, bacterial intracellular viability, and generation of actin stress fibres in HUVECs infected with S. agalactiae. CONCLUSIONS ROS generation via the NADPH oxidase pathway contributes to invasion of S. agalactiae in human endothelial cells accompanied by cytoskeletal reorganisation through the PI3K/Akt pathway, which provides novel evidence for the involvement of oxidative stress in S. agalactiae pathogenesis. PMID:29641644

A commercial mixture of the brominated flame retardant pentabrominated diphenyl ether (DE-71) induces respiratory burst in human neutrophil granulocytes in vitro.

PubMed

Reistad, Trine; Mariussen, Espen

2005-09-01

Polybrominated diphenyl ethers (PBDEs) are widely used brominated flame retardants (BFRs), which have become ubiquitous in the environment. This study investigates the effects of the pentabrominated diphenyl ether mixture, DE-71, on human neutrophil granulocytes in vitro. DE-71 enhanced production of reactive oxygen species (ROS) in a concentration-dependent manner measured as lucigenin-amplified chemiluminescence. Octabrominated diphenyl ether (OBDE), decabrominated diphenyl ether (DBDE), and the non-brominated diphenyl ether did not induce ROS formation at the concentrations tested. DPI (4 microM), an inhibitor of the NADPH oxidase completely inhibited DE-71 induced ROS formation, highlighting a role for NADPH oxidase activation. The protein kinase C inhibitor BIM (0.25 microM) and the selective chelator of intracellular calcium, BAPTA-AM (5 microM), also inhibited NADPH oxidase activation, indicating a calcium-dependent activation of PKC. ROS formation was also inhibited by the tyrosine kinase inhibitor tyrphostin (1 microM), the phospholipase C inhibitor ET-18-OCH3 (5 microM), and the phosphatidylinositol-3 kinase inhibitor LY294002 (25 microM). Alterations in intracellular calcium were measured using fura-2/AM, and a significant increase was measured after exposure to DE-71 both with and without extracellular calcium. The tetra brominated compound BDE-47 also enhanced ROS formation in a concentration dependent manner. The combination of DE-71 with the bacteria-derived N-formyl peptide fMLP and PCB153 induced an additive effect in the lucigenin assay. We suggest that tyrosine kinase mediated activation of PI3K could result in enhanced activation of calcium-dependent PKC by enhanced PLC activity, followed by intracellular calcium release leading to ROS formation in neutrophil granulocytes.

Polyamine oxidase activity in rats treated with mitoguazone: specific and permanent decrease in thymus.

PubMed

Ferioli, M E; Armanni, A

2003-01-01

To extend the knowledge on the role of polyamine oxidase in thymus physiology, we evaluated the in vivo effect of the polyamine biosynthetic pathway inhibitor mitoguazone. The drug markedly and permanently decreased the enzyme activity in the organ, in which the level of putrescine also decreased at the later times observed. A byproduct of the reaction catalyzed by polyamine oxidase is hydrogen peroxide, a well known inducer of apoptosis. The decrease in polyamine oxidase activity, with the consequent decrease in hydrogen peroxide production, is correlated with a positive effect on thymus physiology. Since mitoguazone has been successfully employed in patients with AIDS-related diseases, in which the reconstitution of the immune function is a favorable prognostic index, we hypothesized that mitoguazone may have the thymus as target organ, and that the decrease in polyamine oxidase activity may have a role in the positive effect of the drug.

Benzyloxynitrostyrene analogues - A novel class of selective and highly potent inhibitors of monoamine oxidase B.

PubMed

Van der Walt, Mietha M; Terre'Blanche, Gisella; Petzer, Jacobus P; Petzer, Anél

2017-01-05

This study examines a series of novel 3-benzyloxy-β-nitrostyrene analogues as a novel class of inhibitors of the monoamine oxidase (MAO) enzymes. MAO inhibitors are considered useful for the treatment of depression and Parkinson's disease, and have recently attracted attention as potential therapeutic agents for a range of disorders including Alzheimer's disease, prostate cancer and certain cardiomyopathies. This study shows that the 3-benzyloxy-β-nitrostyrene analogues are potent inhibitors of the MAO-B isoform with IC 50 values in the nanomolar range (39-565 nM). Significantly, effectiveness towards MAO-B inhibition seems to be governed by the introduction of a 4″-fluoro-substituent on the benzyloxy ring, with compound 2b exhibiting the highest degree of MAO-B inhibition potency (IC 50  = 0.039 μM) and selectivity (SI = 166) among the compounds investigated. Since some of the 3-benzyloxy-β-nitrostyrene analogues possess potencies that are comparable to that of the reversible inhibitor, safinamide (IC 50  = 0.080 μM), it may be concluded that this class may be promising leads for the development of reversible and selective MAO-B inhibitors, that may be useful for the management of Parkinson's disease. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

Mechanism and characteristics of stimuli-dependent ROS generation in undifferentiated HL-60 cells.

PubMed

Muranaka, Shikibu; Fujita, Hirofumi; Fujiwara, Takuzo; Ogino, Tetsuya; Sato, Eisuke F; Akiyama, Jitsuo; Imada, Isuke; Inoue, Masayasu; Utsumi, Kozo

2005-01-01

It has been widely believed that undifferentiated human promyelocytic leukemia cells (HL-60) have no ability to generate reactive oxygen species (ROS) responding to stimuli. We report here that undifferentiated HL-60 cells possess NADPH oxidase and that generation of superoxide can be measured using a highly sensitive chemiluminescence dye, L-012. Five subunits of NADPH oxidase, namely, gp91(phox), p22(phox), p67(phox), p47(phox), and Rac 2, were detected in undifferentiated HL-60 cells by immunoblotting analysis. The contents of these NADPH oxidase components in the cells were increased with the differentiation induced by phorbol myristate acetate (PMA), except for p22(phox). Messenger RNAs of these subunits were also detected by the RT-PCR method, and their expressions increased except that of p22(phox) with the differentiation induced by PMA. Kinetic analysis using L-012 revealed that HL-60 cells generated substantial amounts of ROS by various stimulants, including formylmethionyl-leucyl-phenylalanine, PMA, myristic acid, and a Ca2+ ionophore, A23187. Both diphenyleneiodonium (an inhibitor of FAD-dependent oxidase) and apocynin (a specific inhibitor of NADPH oxidase) suppressed this stimuli-dependent ROS generation. Genistein, staurosporine, uric acid, and sodium azide inhibited the ROS generation in undifferentiated HL-60 cells in a similar way to that in undifferentiated neutrophils. These results suggested that the mechanism of ROS generation in undifferentiated HL-60 cells is the same as that in primed neutrophils.

A novel multi-hyphenated analytical method to simultaneously determine xanthine oxidase inhibitors and superoxide anion scavengers in natural products.

PubMed

Qi, Jin; Sun, Li-Qiong; Qian, Steven Y; Yu, Bo-Yang

2017-09-01

Natural products, such as rosmarinic acid and apigenin, can act as xanthine oxidase inhibitors (XOIs) as well as superoxide anion scavengers, and have potential for treatment of diseases associated with high uric acid levels and oxidative stress. However, efficient simultaneous screening of these two bioactivities in natural products has been challenging. We have developed a novel method by assembling a multi-hyphenated high performance liquid chromatography (HPLC) system that combines a photo-diode array, chemiluminescence detector and a HPLC system with a variable wavelength detector, to simultaneously detect components that act as both XOIs and superoxide anion scavengers in natural products. Superoxide anion scavenging activity in the analyte was measured by on-line chemiluminescence chromatography based on pyrogallol-luminol oxidation, while xanthine oxidase inhibitory activity was determined by semi-on-line HPLC analysis. After optimizing multiple elements, including chromatographic conditions (e.g., organic solvent concentration and mobile phase pH), concentrations of xanthine/xanthine oxidase and reaction temperature, our validated analytical method was capable of mixed sample analysis. The final results from our method are presented in an easily understood visual format including comprehensive bioactivity data of natural products. Copyright © 2017. Published by Elsevier B.V.

Pro-inflammatory effects of interleukin-17A on vascular smooth muscle cells involve NAD(P)H- oxidase derived reactive oxygen species.

PubMed

Pietrowski, Eweline; Bender, Bianca; Huppert, Jula; White, Robin; Luhmann, Heiko J; Kuhlmann, Christoph R W

2011-01-01

T cells are known for their contribution to the inflammatory element of atherosclerosis. Recently, it has been demonstrated that the Th17 derived cytokine IL-17 is involved in the pro-inflammatory response of vascular smooth muscle cells (VSMC). The aim of the present study was to examine whether reactive oxygen species (ROS) might be involved in this context. The effect of IL-17A on ROS generation was examined using the fluorescent dye 2'7'-dichlorodihydrofluorescein (H(2)DCF) in primary murine VSMC. IL-17A induced an increase in H(2)DCF fluorescence in VSMC, and this effect was blocked by the NAD(P)H-oxidase inhibitor apocynin and siRNA targeting Nox2. The p38-MAPK inhibitors SB203580 and SB202190 dose-dependently reduced the IL-17A induced ROS production. The IL-17A induced release of the pro-inflammatory cytokines IL-6, G-CSF, GM-CSF and MCP-1 from VSMC, as detected by the Luminex technology, was completely abolished by NAD(P)H-oxidase inhibition. Taken together, our data indicate that IL-17A causes the NAD(P)H-oxidase dependent generation of ROS leading to a pro-inflammatory activation of VSMC. Copyright © 2010 S. Karger AG, Basel.

Monoamine oxidase A (MAO A) inhibitors decrease glioma progression.

PubMed

Kushal, Swati; Wang, Weijun; Vaikari, Vijaya Pooja; Kota, Rajesh; Chen, Kevin; Yeh, Tzu-Shao; Jhaveri, Niyati; Groshen, Susan L; Olenyuk, Bogdan Z; Chen, Thomas C; Hofman, Florence M; Shih, Jean C

2016-03-22

Glioblastoma (GBM) is an aggressive brain tumor which is currently treated with temozolomide (TMZ). Tumors usually become resistant to TMZ and recur; no effective therapy is then available. Monoamine Oxidase A (MAO A) oxidizes monoamine neurotransmitters resulting in reactive oxygen species which cause cancer. This study shows that MAO A expression is increased in human glioma tissues and cell lines. MAO A inhibitors, clorgyline or the near-infrared-dye MHI-148 conjugated to clorgyline (NMI), were cytotoxic for glioma and decreased invasion in vitro. Using the intracranial TMZ-resistant glioma model, clorgyline or NMI alone or in combination with low-dose TMZ reduced tumor growth and increased animal survival. NMI was localized specifically to the tumor. Immunocytochemistry studies showed that the MAO A inhibitor reduced proliferation, microvessel density and invasion, and increased macrophage infiltration. In conclusion, we have identified MAO A inhibitors as potential novel stand-alone drugs or as combination therapy with low dose TMZ for drug-resistant gliomas. NMI can also be used as a non-invasive imaging tool. Thus has a dual function for both therapy and diagnosis.

Novel 2H-chromen-2-one derivatives of resveratrol: Design, synthesis, modeling and use as human monoamine oxidase inhibitors.

PubMed

Ruan, Ban-Feng; Cheng, Hui-Jie; Ren, Jing; Li, Hong-Lin; Guo, Lu-Lu; Zhang, Xing-Xing; Liao, Chenzhong

2015-10-20

Using a fragment-based drug design strategy, two biomedical interesting fragments, resveratrol and coumarin were linked to design a series of novel human monoamine oxidase (hMAO) inhibitors with a scaffold of 3-((E)-3-(2-((E)-styryl)phenyl)acryloyl)-2H-chromen-2-one, which demonstrated a very interesting selectivity profile against hMAO-A and hMAO-B: some compounds with this scaffold are selective hMAO-A inhibitors, whereas some are selective hMAO-B inhibitors. The small changes in the substituents of the coumarin moiety led to this interesting selectivity profile. The most potent selective hMAO-B inhibitor D7 has a selectivity ratio of 20.93, with an IC₅₀ value of 2.78 μM, similar or better than selegiline (IC₅₀ = 2.89 μM), a selective hMAO-B inhibitor currently in the market for the treatment of Parkinson's disease. Our modeling study indicates that Tyr 326 of hMAO-B (or corresponded Ile 335 of hMAO-A) may be the determinant for the specificity of these compounds. The selectivity profile of compounds reported herein suggests that we can further develop both selective hMAO-A and hMAO-B inhibitors based on this novel scaffold. Copyright © 2015 Elsevier Masson SAS. All rights reserved.

Monoamine oxidase-B (MAO-B) inhibitors: implications for disease-modification in Parkinson’s disease

PubMed Central

2013-01-01

There is a substantial amount of evidence from experimental parkinsonian models to show the neuroprotective effects of monoamine oxidase-B (MAOB) inhibitors. They have been studied for their potential disease-modifying effects in Parkinson’s disease (PD) for over 20 years in various clinical trials. This review provides a summary of the clinical trials and discusses the implications of their results in the context of disease-modification in PD. Earlier clinical trials on selegiline were confounded by symptomatic effects of this drug. Later clinical trials on rasagiline using delayed-start design provide newer insights in disease-modification in PD but success in achieving the aims of this strategy remain elusive due to obstacles, some of which may be insurmountable. PMID:24011391

Rationale and design of a multicenter randomized study for evaluating vascular function under uric acid control using the xanthine oxidase inhibitor, febuxostat: the PRIZE study.

PubMed

Oyama, Jun-Ichi; Tanaka, Atsushi; Sato, Yasunori; Tomiyama, Hirofumi; Sata, Masataka; Ishizu, Tomoko; Taguchi, Isao; Kuroyanagi, Takanori; Teragawa, Hiroki; Ishizaka, Nobukazu; Kanzaki, Yumiko; Ohishi, Mitsuru; Eguchi, Kazuo; Higashi, Yukihito; Yamada, Hirotsugu; Maemura, Koji; Ako, Junya; Bando, Yasuko K; Ueda, Shinichiro; Inoue, Teruo; Murohara, Toyoaki; Node, Koichi

2016-06-18

Xanthine oxidase inhibitors are anti-hyperuricemic drugs that decrease serum uric acid levels by inhibiting its synthesis. Xanthine oxidase is also recognized as a pivotal enzyme in the production of oxidative stress. Excess oxidative stress induces endothelial dysfunction and inflammatory reactions in vascular systems, leading to atherosclerosis. Many experimental studies have suggested that xanthine oxidase inhibitors have anti-atherosclerotic effects by decreasing in vitro and in vivo oxidative stress. However, there is only limited evidence on the clinical implications of xanthine oxidase inhibitors on atherosclerotic cardiovascular disease in patients with hyperuricemia. We designed the PRIZE study to evaluate the effects of febuxostat on a surrogate marker of cardiovascular disease risk, ultrasonography-based intima-media thickness of the carotid artery in patients with hyperuricemia. The study is a multicenter, prospective, randomized, open-label and blinded-endpoint evaluation (PROBE) design. A total of 500 patients with asymptomatic hyperuricemia (uric acid >7.0 mg/dL) and carotid intima-media thickness ≥1.1 mm will be randomized centrally to receive either febuxostat (10-60 mg/day) or non-pharmacological treatment. Randomization is carried out using the dynamic allocation method stratified according to age (<65, ≥65 year), gender, presence or absence of diabetes mellitus, serum uric acid (<8.0, ≥8.0 mg/dL), and carotid intima-media thickness (<1.3, ≥1.3 mm). In addition to administering the study drug, we will also direct lifestyle modification in all participants, including advice on control of body weight, sleep, exercise and healthy diet. Carotid intima-media thickness will be evaluated using ultrasonography performed by skilled technicians at a central laboratory. Follow-up will be continued for 24 months. The primary endpoint is percentage change in mean intima-media thickness of the common carotid artery 24 months after baseline, measured by carotid ultrasound imaging. PRIZE will be the first study to provide important data on the effects of febuxostat on atherosclerosis in patients with asymptomatic hyperuricemia. Trial Registration Unique trial Number, UMIN000012911 ( https://upload.umin.ac.jp/cgi-open-bin/ctr/ctr.cgi?function=brows&action=brows&type=summary&recptno=R000015081&language=E ).

Polyphenol oxidase inhibitor from blue mussel (Mytilus edulis) extract.

PubMed

Schulbach, Kurt F; Johnson, Jodie V; Simonne, Amarat H; Kim, Jeong-Mok; Jeong, Yoonhwa; Yagiz, Yavuz; Marshall, Maurice R

2013-03-01

Enzymatic browning remains a problem for the fruit and vegetable industry, especially new emerging markets like pre-cuts. A crude inhibitor from blue mussel (Mytilus edulis) showed broad inhibition for apple (58%), mushroom (32%), and potato (44%) polyphenol oxidase (PPO) and was further characterized. Inhibition increased as the concentration of inhibitor increased in the reaction mixture eventually leveling off at a maximum inhibition of 92% for apple PPO. The inhibitor was capable of bleaching the brown color formed in the reaction mixture with apple PPO. Identification of the inhibitor by mass spectrometry and high-performance liquid chromatography revealed it to be hypotaurine (C2 H7 NO2 S). Hypotaurine and other sulfinic acid analogs (methane and benzene sulfinic acids) showed very good inhibition for apple PPO at various concentrations with the highest inhibition occurring at 500 μM for hypotaurine (89%), methane sulfinic acid (100%), and benzene sulfinic acid (100%). An inhibitor found in the expressed liquid from blue mussel shows very good inhibition on enzymatic browning. Since this enzyme is responsible for losses to the fruit and vegetable industry, natural inhibitors that prevent browning would be valuable. Finding alternative chemistries that inhibit browning and understanding their mode of action would be beneficial to the fruit and vegetable industries and their segments such as pre-cuts, juices, and so on. Inhibitors from products ingested by consumers are more acceptable as natural ingredients. © 2013 Institute of Food Technologists®

Synthesis and evaluation of 2-benzylidene-1-tetralone derivatives for monoamine oxidase inhibitory activity.

PubMed

Amakali, Klaudia T; Legoabe, Lesetja Jan; Petzer, Anel; Petzer, Jacobus P

2018-05-01

Chalcone has been identified as a promising lead for the design of monoamine oxidase (MAO) inhibitors. This study attempted to discover potent and selective chalcone-derived MAO inhibitors by synthesising a series consisting of various cyclic chalcone derivatives. The cyclic chalcones were selected based on the possibility that their restricted structures would confer a higher degree of MAO isoform selectivity, and included the following chemical classes: 1-indanone, 1-tetralone, 1-benzosuberone, chromone, thiochromone, 4-chromanone and 4-thiochromanone. The results showed that the cyclic chalcones are in general good potency, and in most instances specific inhibitors of the human MAO-B isoform. Among these compounds, the 4-chromanone derivative was the most potent MAO-B inhibitor with an IC50 value of 0.156 µM. To further investigate the MAO inhibition of cyclic chalcones, a series of twenty-three 2-benzylidene-1-tetralone derivatives were synthesised and evaluated as MAO inhibitors. Most 2-benzylidene-1-tetralones possess good inhibitory activity and specificity for MAO-B with the most potent inhibitor displaying an IC50 value of 0.0064 µM, while the most potent MAO-A inhibitor possessed an IC50 value of 0.754 µM. This study thus shows that certain cyclic chalcones are human MAO-B inhibitors, compounds that could be suitable for the treatment of neurodegenerative disorders such as Parkinson's disease. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Formation and implications of alpha-synuclein radical in Maneb- and paraquat-induced models of Parkinson’s disease

PubMed Central

Kumar, Ashutosh; Leinisch, Fabian; Kadiiska, Maria B.; Corbett, Jean; Mason, Ronald P.

2015-01-01

Parkinson’s disease (PD) is a debilitating, progressive, neurodegenerative disorder characterized by progressive loss of dopaminergic neurons and motor deficits. Alpha-synuclein-containing aggregates represent a feature of a variety of neurodegenerative disorders, including PD; however, the mechanism that initiates and promotes intraneuronal alpha-synuclein aggregation remains unknown. We hypothesized protein radical formation as an initiating mechanism for alpha-synuclein aggregation. Therefore, we used the highly sensitive immuno-spin trapping technique to investigate protein radical formation as a possible mechanism of alpha-synuclein aggregation as well as to investigate the source of protein radical formation in the midbrains of Maneb and paraquat coexposed mice. Coexposure to Maneb and paraquat for 6 weeks resulted in active microgliosis, NADPH oxidase activation, and inducible nitric oxide synthase (iNOS) induction, which culminated in protein radical formation in the midbrains of mice. Results obtained with immuno-spin trapping and immunoprecipitation experiments confirmed formation of alpha-synuclein radicals in dopaminergic neurons of exposed mice. Free radical formation requires NADPH oxidase and iNOS, as indicated by decreased protein radical formation in knockout mice (P47phox−/− and iNOS−/−) and in mice treated with inhibitors such as FeTPPS (a peroxynitrite decomposition catalyst), 1400W (an iNOS inhibitor), or apocynin (a NADPH oxidase inhibitor). Concurrence of protein radical formation with dopaminergic neuronal death indicated a link between protein radicals and disease progression. Taken together, these results show for the first time the formation and detection of the alpha-synuclein radical and suggest that NADPH oxidase and iNOS play roles in peroxynitrite-mediated protein radical formation and subsequent neuronal death in the midbrains of Maneb and paraquat coexposed mice. PMID:25952542

Effects of co-administration of dietary sodium arsenite and an NADPH oxidase inhibitor on the rat bladder epithelium.

PubMed

Suzuki, Shugo; Arnold, Lora L; Pennington, Karen L; Kakiuchi-Kiyota, Satoko; Cohen, Samuel M

2009-06-30

Arsenite (As(III)), an inorganic arsenical, is a known human carcinogen, inducing tumors of the skin, urinary bladder and lung. It is metabolized to organic methylated arsenicals. Oxidative stress has been suggested as a mechanism for arsenic-induced carcinogenesis. Reactive oxygen species (ROS) can be important factors for carcinogenesis and tumor progression. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase is known to produce intracellular ROS, therefore, we investigated the ability of apocynin (acetovanillone), an NADPH oxidase inhibitor, to inhibit the cytotoxicity and regenerative cell proliferation of arsenic in vitro and in vivo. Apocynin had similar effects in reducing the cytotoxicity of As(III) and dimethylarsinous acid (DMA(III)) in rat urothelial cells in vitro. When tested at the same concentrations as apocynin, other antioxidants, such as l-ascorbate and N-acetylcysteine, did not inhibit As(III)-induced cytotoxicity but they were more effective at inhibiting DMA(III)-induced cytotoxicity compared with apocynin. In vivo, female rats were treated for 3 weeks with 100ppm As(III). Immunohistochemical staining for 8-hydroxy-2'-deoxyguanosine (8-OHdG) showed that apocynin reduced oxidative stress partially induced by As(III) treatment on rat urothelium, and significantly reduced the cytotoxicity of superficial cells detected by scanning electron microscopy (SEM). However, based on the incidence of simple hyperplasia and the bromodeoxyuridine (BrdU) labeling index, apocynin did not inhibit As(III)-induced urothelial cell proliferation. These data suggest that the NADPH oxidase inhibitor, apocynin, may have the ability to partially inhibit arsenic-induced oxidative stress and cytotoxicity of the rat bladder epithelium in vitro and in vivo. However, apocynin did not inhibit the regenerative cell proliferation induced by arsenite in a short-term study.

Differential involvement of various sources of reactive oxygen species in thyroxin-induced hemodynamic changes and contractile dysfunction of the heart and diaphragm muscles

PubMed Central

Elnakish, Mohammad T.; Schultz, Eric J.; Gearinger, Rachel L.; Saad, Nancy S.; Rastogi, Neha; Ahmed, Amany A.E.; Mohler, Peter J.; Janssen, Paul M.L.

2015-01-01

Thyroid hormones are key regulators of basal metabolic state and oxidative metabolism. Hyperthyroidism has been reported to cause significant alterations in hemodynamics, and in cardiac and diaphragm muscle function, all of which have been linked to increased oxidative stress. However, the definite source of increased reactive oxygen species (ROS) in each of these phenotypes is still unknown. The goal of the current study was to test the hypothesis that thyroxin (T4) may produce distinct hemodynamic, cardiac, and diaphragm muscle abnormalities by differentially affecting various sources of ROS. Wild-type and T4 mice with and without 2-week treatments with allopurinol (xanthine oxidase inhibitor), apocynin (NADPH oxidase inhibitor), L-NIO (nitric oxide synthase inhibitor), or MitoTEMPO (mitochondria-targeted antioxidant) were studied. Blood pressure and echocardiography were noninvasively evaluated, followed by ex vivo assessments of isolated heart and diaphragm muscle functions. Treatment with L-NIO attenuated the T4-induced hypertension in mice. However, apocynin improved the left-ventricular (LV) dysfunction without preventing the cardiac hypertrophy in these mice. Both allopurinol and MitoTEMPO reduced the T4-induced fatigability of the diaphragm muscles. In conclusion, we show here for the first time that T4 exerts differential effects on various sources of ROS to induce distinct cardiovascular and skeletal muscle phenotypes. Additionally, we find that T4-induced LV dysfunction is independent of cardiac hypertrophy and NADPH oxidase is a key player in this process. Furthermore, we prove the significance of both xanthine oxidase and mitochondrial ROS pathways in T4-induced fatigability of diaphragm muscles. Finally, we confirm the importance of the nitric oxide pathway in T4-induced hypertension. PMID:25795514

A preliminary neutron diffraction study of rasburicase, a recombinant urate oxidase enzyme, complexed with 8-azaxanthin

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

Budayova-Spano, Monika, E-mail: spano@embl-grenoble.fr; Institut Laue-Langevin, 6 Rue Jules Horowitz, BP 156, 38042 Grenoble; Bonneté, Françoise

2006-03-01

Neutron diffraction data of hydrogenated recombinant urate oxidase enzyme (Rasburicase), complexed with a purine-type inhibitor 8-azaxanthin, was collected to 2.1 Å resolution from a crystal grown in D{sub 2}O by careful control and optimization of crystallization conditions via knowledge of the phase diagram. Deuterium atoms were clearly seen in the neutron-scattering density map. Crystallization and preliminary neutron diffraction measurements of rasburicase, a recombinant urate oxidase enzyme expressed by a genetically modified Saccharomyces cerevisiae strain, complexed with a purine-type inhibitor (8-azaxanthin) are reported. Neutron Laue diffraction data were collected to 2.1 Å resolution using the LADI instrument from a crystal (grownmore » in D{sub 2}O) with volume 1.8 mm{sup 3}. The aim of this neutron diffraction study is to determine the protonation states of the inhibitor and residues within the active site. This will lead to improved comprehension of the enzymatic mechanism of this important enzyme, which is used as a protein drug to reduce toxic uric acid accumulation during chemotherapy. This paper illustrates the high quality of the neutron diffraction data collected, which are suitable for high-resolution structural analysis. In comparison with other neutron protein crystallography studies to date in which a hydrogenated protein has been used, the volume of the crystal was relatively small and yet the data still extend to high resolution. Furthermore, urate oxidase has one of the largest primitive unit-cell volumes (space group I222, unit-cell parameters a = 80, b = 96, c = 106 Å) and molecular weights (135 kDa for the homotetramer) so far successfully studied with neutrons.« less

The mitochondrial-targeted antioxidant MitoQ ameliorates metabolic syndrome features in obesogenic diet-fed rats better than Apocynin or Allopurinol.

PubMed

Feillet-Coudray, Christine; Fouret, Gillen; Ebabe Elle, Raymond; Rieusset, Jennifer; Bonafos, Beatrice; Chabi, Beatrice; Crouzier, David; Zarkovic, Kamelija; Zarkovic, Neven; Ramos, Jeanne; Badia, Eric; Murphy, Michael P; Cristol, Jean Paul; Coudray, Charles

2014-10-01

The prevalence of metabolic syndrome (MetS) components including obesity, dyslipidemia, insulin resistance (IR), and hepatic steatosis is rapidly increasing in wealthy societies. It is accepted that inflammation/oxidative stress are involved in the initiation/evolution of the MetS features. The present work was designed to evaluate the effects of three major cellular ROS production systems on obesity, glucose tolerance, and hepatic steatosis development and on oxidative stress onset. To do so, 40 young male Sprague-Dawley rats were divided into 5 groups: 1-control group, 2-high fat (HF) group (60% energy from fat), 3-HF+ MitoQ (mitochondrial ROS scavenger), 4-HF+ Apocynin (NADPH oxidase inhibitor), 5-HF+ Allopurinol (xanthine oxidase inhibitor). After 8 weeks of these treatments, surrogate MetS, mitochondrial function, and oxidative stress markers were measured in blood and liver. As expected, rats that were fed the HF diet exhibited increased body weight, glucose intolerance, overt hepatic steatosis, and increased hepatic oxidative stress. The impacts of the studied ROS inhibitors on these aspects of the MetS were markedly different. MitoQ showed the most clinically relevant effects, attenuating body weight gain and glucose intolerance provoked by the HF diet. Both Apocynin and Allopurinol showed limited effects suggesting secondary roles of xanthine oxidase (XO) or NADPH oxidase-dependent ROS production in the onset of oxidative stress-dependent obesity, glucose intolerance, and hepatic steatosis process. Thus, MitoQ revealed the central role of mitochondrial oxidative stress in the development of MetS and suggested that mitochondria-targeted antioxidants may be worth considering as potentially helpful therapies for MetS features.

Monoamine Oxidase B Inhibitors in Parkinson's Disease.

PubMed

Dezsi, Livia; Vecsei, Laszlo

2017-01-01

Parkinson's disease (PD) is a neurodegenerative disorder with a prevalence increasing with age. Oxidative stress and glutamate toxicity are involved in its pathomechanism. There are still many unmet needs of PD patients, including the alleviation of motor fluctuations and dyskinesias, and the development of therapies with neuroprotective potential. To give an overview of the pharmacological properties, the efficacy and safety of the monoamine oxidase B (MAO-B) inhibitors in the treatment of PD, with special focus on the results of randomized clinical trials. A literature search was conducted in PubMed for 'PD treatment', 'MAO-B inhibitors', 'selegiline', 'rasagiline', 'safinamide' and 'clinical trials' with 'MAO-B inhibitors' in 'Parkinson' disease'. MAO-B inhibitors have a favorable pharmacokinetic profile, improve the dopamine deficient state and may have neuroprotective properties. Safinamide exhibits an anti-glutamatergic effect as well. When applied as monotherapy, MAO-B inhibitors provide a modest, but significant improvement of motor function and delay the need for levodopa. Rasagiline and safinamide were proven safe and effective when added to a dopamine agonist in early PD. As add-on to levodopa, MAO-B inhibitors significantly reduced off-time and were comparable in efficacy to COMT inhibitors. Improvements were achieved as regards certain non-motor symptoms as well. Due to the efficacy shown in clinical trials and their favorable side-effect profile, MAO-B inhibitors are valuable drugs in the treatment of PD. They are recommended as monotherapy in the early stages of the disease and as add-on therapy to levodopa in advanced PD. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org.

Design, synthesis and evaluation of coumarin-pargyline hybrids as novel dual inhibitors of monoamine oxidases and amyloid-β aggregation for the treatment of Alzheimer's disease.

PubMed

Yang, Hua-Li; Cai, Pei; Liu, Qiao-Hong; Yang, Xue-Lian; Li, Fan; Wang, Jin; Wu, Jia-Jia; Wang, Xiao-Bing; Kong, Ling-Yi

2017-09-29

A series of coumarin-pargyline hybrids (4a-x) have been designed, synthesized and evaluated as novel dual inhibitors of Alzheimer's disease (AD). Most of the compounds exhibited a potent ability to inhibit amyloid-β (Aβ) aggregation and monoamine oxidases. In particular, compound 4x exhibited remarkable inhibitory activities against monoamine oxidases (IC 50 , 0.027 ± 0.004 μM for MAO-B; 3.275 ± 0.040 μM for MAO-A) and Aβ 1-42 aggregation (54.0 ± 1.1%, 25 μM). Moreover, compound 4x showed low toxicity according to in vitro cell toxicity test. The results of the parallel artificial membrane permeability assay for blood-brain barrier indicated that compound 4x would be potent to cross the blood-brain barrier. Collectively, these findings demonstrate that compound 4x was an effective and promising candidate for AD therapy. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Ascorbate protects endothelial barrier function during septic insult: Role of protein phosphatase type 2A.

PubMed

Han, Min; Pendem, Suresh; Teh, Suet Ling; Sukumaran, Dinesh K; Wu, Feng; Wilson, John X

2010-01-01

Endothelial barrier dysfunction contributes to morbidity in sepsis. We tested the hypothesis that raising the intracellular ascorbate concentration protects the endothelial barrier from septic insult by inhibiting protein phosphatase type 2A. Monolayer cultures of microvascular endothelial cells were incubated with ascorbate, dehydroascorbic acid (DHAA), the NADPH oxidase inhibitors apocynin and diphenyliodonium, or the PP2A inhibitor okadaic acid and then were exposed to septic insult (lipopolysaccharide and interferon-gamma). Under standard culture conditions that depleted intracellular ascorbate, septic insult stimulated oxidant production and PP2A activity, dephosphorylated phosphoserine and phosphothreonine residues in the tight junction-associated protein occludin, decreased the abundance of occludin at cell borders, and increased monolayer permeability to albumin. NADPH oxidase inhibitors prevented PP2A activation and monolayer leak, showing that these changes required reactive oxygen species. Okadaic acid, at a concentration that inhibited PP2A activity and monolayer leak, prevented occludin dephosphorylation and redistribution, implicating PP2A in the response of occludin to septic insult. Incubation with ascorbate or DHAA raised intracellular ascorbate concentrations and mitigated the effects of septic insult. In conclusion, ascorbate acts within microvascular endothelial cells to inhibit septic stimulation of oxidant production by NADPH oxidase and thereby prevents PP2A activation, PP2A-dependent dephosphorylation and redistribution of occludin, and disruption of the endothelial barrier. Copyright 2009 Elsevier Inc. All rights reserved.

Monoamine oxidase A inhibitor occupancy during treatment of major depressive episodes with moclobemide or St. John’s wort: an [11C]-harmine PET study

PubMed Central

Sacher, Julia; Houle, Sylvain; Parkes, Jun; Rusjan, Pablo; Sagrati, Sandra; Wilson, Alan A.; Meyer, Jeffrey H.

2011-01-01

Background Monoamine oxidase A (MAO-A) inhibitor antidepressants raise levels of multiple monoamines, whereas the selective serotonin reuptake inhibitors (SSRIs) only raise extracellular serotonin. Despite this advantage of MAO-A inhibitors, there is much less frequent development of MAO inhibitors compared with SSRIs. We sought to measure brain MAO-A occupancy after 6 weeks of treatment in depressed patients with a clinically effective dose of a selective MAO-A inhibitor and measure MAO-A occupancy after repeated administration of St. John’s wort, an herb purported to have MAO-A inhibitor properties. Methods Participants underwent 2 [11C]-harmine positron emission tomography scans. Healthy controls completed a test–retest condition, and depressed patients were scanned before and after repeated administration of moclobemide or St. John’s wort for 6 weeks at the assigned dose. We measured MAO-A VT, an index of MAO-A density, in the prefrontal, anterior cingulate and anterior temporal cortices, putamen, thalamus, midbrain and hippocampus. Results We included 23 participants (10 controls and 13 patients with major depressive disorder [MDD]) in our study. Monoamine oxidase A VT decreased significantly throughout all regions after moclobemide treatment in patients with MDD compared with controls (repeated-measures analysis of variance, F1,15 = 71.08–130.06, p < 0.001 for all regions, mean occupancy 74% [standard deviation 6%]). Treatment with St. John’s wort did not significantly alter MAO-A VT. Limitations The occupancy estimates are limited by the sample size of each treatment group; hence, our estimate for the overall moclobemide occupancy of 74% has a 95% confidence interval of 70%–78%, and we can estimate with 95% certainty that the occupancy of St. John’s wort is less than 5%. Conclusion For new MAO-A inhibitors, about 74% occupancy at steady-state dosing is desirable. Consistent with this, St. John’s wort should not be classified as an MAO-A inhibitor. The magnitude of MAO-A blockade during moclobemide treatment exceeds the elevation of MAO-A binding during illness by at least 30%, suggesting that the treatment effect should exceed the disease effect when designing selective anti-depressants for this target. PMID:21463543

Putting together a plasma membrane NADH oxidase: a tale of three laboratories.

PubMed

Löw, Hans; Crane, Frederick L; Morré, D James

2012-11-01

The observation that high cellular concentrations of NADH were associated with low adenylate cyclase activity led to a search for the mechanism of the effect. Since cyclase is in the plasma membrane, we considered the membrane might have a site for NADH action, and that NADH might be oxidized at that site. A test for NADH oxidase showed very low activity, which could be increased by adding growth factors. The plasma membrane oxidase was not inhibited by inhibitors of mitochondrial NADH oxidase such as cyanide, rotenone or antimycin. Stimulation of the plasma membrane oxidase by iso-proterenol or triiodothyronine was different from lack of stimulation in endoplasmic reticulum. After 25 years of research, three components of a trans membrane NADH oxidase have been discovered. Flavoprotein NADH coenzyme Q reductases (NADH cytochrome b reductase) on the inside, coenzyme Q in the middle, and a coenzyme Q oxidase on the outside as a terminal oxidase. The external oxidase segment is a copper protein with unique properties in timekeeping, protein disulfide isomerase and endogenous NADH oxidase activity, which affords a mechanism for control of cell growth by the overall NADH oxidase and the remarkable inhibition of oxidase activity and growth of cancer cells by a wide range of anti-tumor drugs. A second trans plasma membrane electron transport system has been found in voltage dependent anion channel (VDAC), which has NADH ferricyanide reductase activity. This activity must be considered in relation to ferricyanide stimulation of growth and increased VDAC antibodies in patients with autism. Copyright © 2012 Elsevier Ltd. All rights reserved.

Time-dependent slowly-reversible inhibition of monoamine oxidase A by N-substituted 1,2,3,6-tetrahydropyridines.

PubMed

Wichitnithad, Wisut; O'Callaghan, James P; Miller, Diane B; Train, Brian C; Callery, Patrick S

2011-12-15

A novel class of N-substituted tetrahydropyridine derivatives was found to have multiple kinetic mechanisms of monoamine oxidase A inhibition. Eleven structurally similar tetrahydropyridine derivatives were synthesized and evaluated as inhibitors of MAO-A and MAO-B. The most potent MAO-A inhibitor in the series, 2,4-dichlorophenoxypropyl analog 12, displayed time-dependent mixed noncompetitive inhibition. The inhibition was reversed by dialysis, indicating reversible enzyme inhibition. Evidence that the slow-binding inhibition of MAO-A with 12 involves a covalent bond was gained from stabilizing a covalent reversible intermediate product by reduction with sodium borohydride. The reduced enzyme complex was not reversible by dialysis. The results are consistent with slowly reversible, mechanism-based inhibition. Two tetrahydropyridine analogs that selectively inhibited MAO-A were characterized by kinetic mechanisms differing from the kinetic mechanism of 12. As reversible inhibitors of MAO-A, tetrahydropyridine analogs are at low risk of having an adverse effect of tyramine-induced hypertension. Copyright © 2011 Elsevier Ltd. All rights reserved.

NADPH Oxidase as a Therapeutic Target for Oxalate Induced Injury in Kidneys

PubMed Central

Peck, Ammon B.; Khan, Saeed R.

2013-01-01

A major role of the nicotinamide adenine dinucleotide phosphate (NADPH) oxidase family of enzymes is to catalyze the production of superoxides and other reactive oxygen species (ROS). These ROS, in turn, play a key role as messengers in cell signal transduction and cell cycling, but when they are produced in excess they can lead to oxidative stress (OS). Oxidative stress in the kidneys is now considered a major cause of renal injury and inflammation, giving rise to a variety of pathological disorders. In this review, we discuss the putative role of oxalate in producing oxidative stress via the production of reactive oxygen species by isoforms of NADPH oxidases expressed in different cellular locations of the kidneys. Most renal cells produce ROS, and recent data indicate a direct correlation between upregulated gene expressions of NADPH oxidase, ROS, and inflammation. Renal tissue expression of multiple NADPH oxidase isoforms most likely will impact the future use of different antioxidants and NADPH oxidase inhibitors to minimize OS and renal tissue injury in hyperoxaluria-induced kidney stone disease. PMID:23840917

Mammalian monoamine-oxidizing enzymes, with special reference to benzylamine oxidase in human tissues.

PubMed

Lewinsohn, R

1984-01-01

A review is presented of the monoamine-oxidizing enzymes with special reference to the activity of benzylamine oxidase (BzAO) in human tissues. Methods of study of amine oxidases, properties (chiefly of BzAO) and some problems concerning substrate and inhibitor specificity and multiple forms of monoamine oxidase (MAO) are surveyed. The substrate specificity of human plasma BzAO is compared with that of amine-oxidizing enzymes in plasma or serum of other species. Correlations of plasma BzAO and platelet MAO activity with clinical findings are discussed. The distribution of amine oxidase activities in solid human tissues is reviewed, in particular BzAO in blood vessels and richly-vascularized tissues, as well as kinetic constants and altered patterns of activity of BzAO in human atherosclerosis. Activities of the amine oxidases in non-vascular smooth muscle, in cultured cells, and in various tissues related to human gestation, are discussed. The present knowledge of BzAO is discussed in terms of its possible clinical relevance to several human disease states, and the importance of the enzyme in the human body.

An Updated Review of Tyrosinase Inhibitors

PubMed Central

Chang, Te-Sheng

2009-01-01

Tyrosinase is a multifunctional, glycosylated, and copper-containing oxidase, which catalyzes the first two steps in mammalian melanogenesis and is responsible for enzymatic browning reactions in damaged fruits during post-harvest handling and processing. Neither hyperpigmentation in human skin nor enzymatic browning in fruits are desirable. These phenomena have encouraged researchers to seek new potent tyrosinase inhibitors for use in foods and cosmetics. This article surveys tyrosinase inhibitors newly discovered from natural and synthetic sources. The inhibitory strength is compared with that of a standard inhibitor, kojic acid, and their inhibitory mechanisms are discussed. PMID:19582213

2-Heteroarylidene-1-indanone derivatives as inhibitors of monoamine oxidase.

PubMed

Nel, Magdalena S; Petzer, Anél; Petzer, Jacobus P; Legoabe, Lesetja J

2016-12-01

In the present study a series of fifteen 2-heteroarylidene-1-indanone derivatives were synthesised and evaluated as inhibitors of recombinant human monoamine oxidase (MAO) A and B. These compounds are structurally related to series of heterocyclic chalcone derivatives which have previously been shown to act as MAO-B specific inhibitors. The results document that the 2-heteroarylidene-1-indanones are in vitro inhibitors of MAO-B, displaying IC 50 values of 0.0044-1.53μM. Although with lower potencies, the derivatives also inhibit the MAO-A isoform with IC 50 values as low as 0.061μM. An analysis of the structure-activity relationships for MAO-B inhibition indicates that substitution with the methoxy group on the A-ring leads to a significant enhancement in MAO-B inhibition compared to the unsubstituted homologues while the effect of the heteroaromatic substituent on activity, in decreasing order is: 5-bromo-2-furan>5-methyl-2-furan>2-pyridine≈2-thiophene>cyclohexyl>3-pyridine≈2-furan. It may therefore be concluded that 2-heteroarylidene-1-indanone derivatives are promising leads for the design of MAO inhibitors for the treatment of Parkinson's disease and possibly other neurodegenerative disorders. Copyright © 2016 Elsevier Inc. All rights reserved.

Chromenylchalcones with inhibitory effects on monoamine oxidase B.

PubMed

Jo, Geunhyeong; Ahn, Seunghyun; Kim, Bong-Gyu; Park, Hye Ri; Kim, Young Hwa; Choo, Hyun Ah; Koh, Dongsoo; Chong, Youhoon; Ahn, Joong-Hoon; Lim, Yoongho

2013-12-15

Structure-activity relationship (SAR) calculations were used to find monoamine oxidase-B (MAO-B) inhibitors by identifying pharmacophores exhibiting high inhibitory activities. Several such chromenylchalcones were designed and synthesized accordingly. Their inhibitory effects on MAO-B were determined using an HPLC-based method and an MAO-B enzyme assay kit. (E)-3-(6-Methoxy-2H-chromen-3-yl)-1-(2-methoxyphenyl)prop-2-en-1-one exhibited a half-maximal inhibitory concentration of 320 nM. Its molecular-level binding mode with the three-dimensional structure of MAO-B was elucidated using an in silico docking study. The chromenylchalcone scaffold, which is derived from natural products including isoflavonoids and chalcones, had not been previously reported as an MAO-B inhibitor. Copyright © 2013 Elsevier Ltd. All rights reserved.

Comparison of Monoamine Oxidase Inhibitors in Decreasing Production of the Autotoxic Dopamine Metabolite 3,4-Dihydroxyphenylacetaldehyde in PC12 Cells

PubMed Central

Jinsmaa, Yunden; Sullivan, Patti; Holmes, Courtney; Kopin, Irwin J.; Sharabi, Yehonatan

2016-01-01

According to the catecholaldehyde hypothesis, the toxic dopamine metabolite 3,4-dihydroxyphenylacetaldehyde (DOPAL) contributes to the loss of nigrostriatal dopaminergic neurons in Parkinson’s disease. Monoamine oxidase-A (MAO-A) catalyzes the conversion of intraneuronal dopamine to DOPAL and may serve as a therapeutic target. The “cheese effect”—paroxysmal hypertension evoked by tyramine-containing foodstuffs—limits clinical use of irreversible MAO-A inhibitors. Combined MAO-A/B inhibition decreases DOPAL production in rat pheochromocytoma PC12 cells, but whether reversible MAO-A inhibitors or MAO-B inhibitors decrease endogenous DOPAL production is unknown. We compared the potencies of MAO inhibitors in attenuating DOPAL production and examined possible secondary effects on dopamine storage, constitutive release, synthesis, and auto-oxidation. Catechol concentrations were measured in cells and medium after incubation with the irreversible MAO-A inhibitor clorgyline, three reversible MAO-A inhibitors, or the MAO-B inhibitors selegiline or rasagiline for 180 minutes. Reversible MAO-A inhibitors were generally ineffective, whereas clorgyline (1 nM), rasagiline (500 nM), and selegiline (500 nM) decreased DOPAL levels in the cells and medium. All three drugs also increased dopamine and norepinephrine, decreased 3,4-dihydroxyphenylalanine, and increased cysteinyl-dopamine concentrations in the medium, suggesting increased vesicular uptake and constitutive release, decreased dopamine synthesis, and increased dopamine spontaneous oxidation. In conclusion, clorgyline, rasagiline, and selegiline decrease production of endogenous DOPAL. At relatively high concentrations, the latter drugs probably lose their selectivity for MAO-B. Possibly offsetting increased formation of potentially toxic oxidation products and decreased formation of DOPAL might account for the failure of large clinical trials of MAO-B inhibitors to demonstrate slowing of neurodegeneration in Parkinson’s disease. PMID:26574516

A multiple treatment comparison meta-analysis of monoamine oxidase type B inhibitors for Parkinson's disease.

PubMed

Binde, C D; Tvete, I F; Gåsemyr, J; Natvig, B; Klemp, M

2018-05-30

To the best of our knowledge, there are no systematic reviews or meta-analyses that compare rasagiline, selegiline and safinamide. Therefore, we aimed to perform a drug class review comparing all available monoamine oxidase type B (MAO-B) inhibitors in a multiple treatment comparison. We performed a systematic literature search to identify randomized controlled trials assessing the efficacy of MAO-B inhibitors in patients with Parkinson's disease. MAO-B inhibitors were evaluated either as monotherapy or in combination with levodopa or dopamine agonists. Endpoints of interest were change in the Unified Parkinson's Disease Rating Scale (UPDRS) score and serious adverse events. We estimated the relative effect of each MAO-B inhibitor versus the comparator drug by creating three networks of direct and indirect comparisons. For each of the networks, we considered a joint model. The systematic literature search and study selection process identified 27 publications eligible for our three network analyses. We found the relative effects of rasagiline, safinamide and selegiline treatment given alone and compared to placebo in a model without explanatory variables to be 1.560 (1.409, 1.734), 1.449 (0.873, 2.413) and 1.532 (1.337, 1.757) respectively. We also found all MAO-B inhibitors to be efficient when given together with levodopa. When ranking the MAO-B inhibitors given in combination with levodopa, selegiline was the most effective and rasagiline was the second best. All of the included MAO-B inhibitors were effective compared to placebo when given as monotherapy. Combination therapy with MAO-B inhibitors and levodopa showed that all three MAO-B inhibitors were effective compared to placebo, but selegiline was the most effective drug. © 2018 The British Pharmacological Society.

Resveratrol protects vascular endothelial cells from high glucose-induced apoptosis through inhibition of NADPH oxidase activation-driven oxidative stress.

PubMed

Chen, Feng; Qian, Li-Hua; Deng, Bo; Liu, Zhi-Min; Zhao, Ying; Le, Ying-Ying

2013-09-01

Hyperglycemia-induced oxidative stress has been implicated in diabetic vascular complications in which NADPH oxidase is a major source of reactive oxygen species (ROS) generation. Resveratrol is a naturally occurring polyphenol, which has vasoprotective effects in diabetic animal models and inhibits high glucose (HG)-induced oxidative stress in endothelial cells. We aimed to examine whether HG-induced NADPH oxidase activation and ROS production contribute to glucotoxicity to endothelial cells and the effect of resveratrol on glucotoxicity. Using a murine brain microvascular endothelial cell line bEnd3, we found that NADPH oxidase inhibitor (apocynin) and resveratrol both inhibited HG-induced endothelial cell apoptosis. HG-induced elevation of NADPH oxidase activity and production of ROS were inhibited by apocynin, suggesting that HG induces endothelial cell apoptosis through NADPH oxidase-mediated ROS production. Mechanistic studies revealed that HG upregulated NADPH oxidase subunit Nox1 but not Nox2, Nox4, and p22(phox) expression through NF-κB activation, which resulted in elevation of NADPH oxidase activity and consequent ROS production. Resveratrol prevented HG-induced endothelial cell apoptosis through inhibiting HG-induced NF-κB activation, NADPH oxidase activity elevation, and ROS production. HG induces endothelial cell apoptosis through NF-κB/NADPH oxidase/ROS pathway, which was inhibited by resveratrol. Our findings provide new potential therapeutic targets against brain vascular complications of diabetes. © 2013 John Wiley & Sons Ltd.

Chlorella Induces Stomatal Closure via NADPH Oxidase-Dependent ROS Production and Its Effects on Instantaneous Water Use Efficiency in Vicia faba

PubMed Central

Li, Yan; Xu, Shan-Shan; Gao, Jing; Pan, Sha; Wang, Gen-Xuan

2014-01-01

Reactive oxygen species (ROS) have been established to participate in stomatal closure induced by live microbes and microbe-associated molecular patterns (MAMPs). Chlorella as a beneficial microorganism can be expected to trigger stomatal closure via ROS production. Here, we reported that Chlorella induced stomatal closure in a dose-and time-dependent manner in epidermal peels of Vicia faba. Using pharmacological methods in this work, we found that the Chlorella-induced stomatal closure was almost completely abolished by a hydrogen peroxide (H2O2) scavenger, catalase (CAT), significantly suppressed by an NADPH oxidase inhibitor, diphenylene iodonium chloride (DPI), and slightly affected by a peroxidase inhibitor, salicylhydroxamic acid (SHAM), suggesting that ROS production involved in Chlorella-induced stomatal closure is mainly mediated by DPI-sensitive NADPH oxidase. Additionally, Exogenous application of optimal concentrations of Chlorella suspension improved instantaneous water use efficiency (WUEi) in Vicia faba via a reduction in leaf transpiration rate (E) without a parallel reduction in net photosynthetic rate (Pn) assessed by gas-exchange measurements. The chlorophyll fluorescence and content analysis further demonstrated that short-term use of Chlorella did not influence plant photosynthetic reactions center. These results preliminarily reveal that Chlorella can trigger stomatal closure via NADPH oxidase-dependent ROS production in epidermal strips and improve WUEi in leave levels. PMID:24687099

Chlorella induces stomatal closure via NADPH oxidase-dependent ROS production and its effects on instantaneous water use efficiency in Vicia faba.

PubMed

Li, Yan; Xu, Shan-Shan; Gao, Jing; Pan, Sha; Wang, Gen-Xuan

2014-01-01

Reactive oxygen species (ROS) have been established to participate in stomatal closure induced by live microbes and microbe-associated molecular patterns (MAMPs). Chlorella as a beneficial microorganism can be expected to trigger stomatal closure via ROS production. Here, we reported that Chlorella induced stomatal closure in a dose-and time-dependent manner in epidermal peels of Vicia faba. Using pharmacological methods in this work, we found that the Chlorella-induced stomatal closure was almost completely abolished by a hydrogen peroxide (H2O2) scavenger, catalase (CAT), significantly suppressed by an NADPH oxidase inhibitor, diphenylene iodonium chloride (DPI), and slightly affected by a peroxidase inhibitor, salicylhydroxamic acid (SHAM), suggesting that ROS production involved in Chlorella-induced stomatal closure is mainly mediated by DPI-sensitive NADPH oxidase. Additionally, Exogenous application of optimal concentrations of Chlorella suspension improved instantaneous water use efficiency (WUEi) in Vicia faba via a reduction in leaf transpiration rate (E) without a parallel reduction in net photosynthetic rate (Pn) assessed by gas-exchange measurements. The chlorophyll fluorescence and content analysis further demonstrated that short-term use of Chlorella did not influence plant photosynthetic reactions center. These results preliminarily reveal that Chlorella can trigger stomatal closure via NADPH oxidase-dependent ROS production in epidermal strips and improve WUEi in leave levels.

Activation of Akt by Advanced Glycation End Products (AGEs): Involvement of IGF-1 Receptor and Caveolin-1

PubMed Central

Yang, Su-Jung; Chen, Chen-Yu; Chang, Geen-Dong; Wen, Hui-Chin; Chen, Ching-Yu; Chang, Shi-Chuan; Liao, Jyh-Fei; Chang, Chung-Ho

2013-01-01

Diabetes is characterized by chronic hyperglycemia, which in turn facilitates the formation of advanced glycation end products (AGEs). AGEs activate signaling proteins such as Src, Akt and ERK1/2. However, the mechanisms by which AGEs activate these kinases remain unclear. We examined the effect of AGEs on Akt activation in 3T3-L1 preadipocytes. Addition of AGEs to 3T3-L1 cells activated Akt in a dose- and time-dependent manner. The AGEs-stimulated Akt activation was blocked by a PI3-kinase inhibitor LY 294002, Src inhibitor PP2, an antioxidant NAC, superoxide scavenger Tiron, or nicotinamide adenine dinucleotide phosphate (NAD(P)H) oxidase inhibitor DPI, suggesting the involvement of Src and NAD(P)H oxidase in the activation of PI3-kinase-Akt pathway by AGEs. AGEs-stimulated Src tyrosine phosphorylation was inhibited by NAC, suggesting that Src is downstream of NAD(P)H oxidase. The AGEs-stimulated Akt activity was sensitive to Insulin-like growth factor 1 receptor (IGF-1R) kinase inhibitor AG1024. Furthermore, AGEs induced phosphorylation of IGF-1 receptorβsubunit (IGF-1Rβ) on Tyr1135/1136, which was sensitive to PP2, indicating that AGEs stimulate Akt activity by transactivating IGF-1 receptor. In addition, the AGEs-stimulated Akt activation was attenuated by β-methylcyclodextrin that abolishes the structure of caveolae, and by lowering caveolin-1 (Cav-1) levels with siRNAs. Furthermore, addition of AGEs enhanced the interaction of phospho-Cav-1 with IGF-1Rβ and transfection of 3T3-L1 cells with Cav-1 Y14F mutants inhibited the activation of Akt by AGEs. These results suggest that AGEs activate NAD(P)H oxidase and Src which in turn phosphorylates IGF-1 receptor and Cav-1 leading to activation of IGF-1 receptor and the downstream Akt in 3T3-L1 cells. AGEs treatment promoted the differentiation of 3T3-L1 preadipocytes and addition of AG1024, LY 294002 or Akt inhibitor attenuated the promoting effect of AGEs on adipogenesis, suggesting that IGF-1 receptor, PI3-Kinase and Akt are involved in the facilitation of adipogenesis by AGEs. PMID:23472139

Sildenafil citrate and sildenafil nitrate (NCX 911) are potent inhibitors of superoxide formation and gp91phox expression in porcine pulmonary artery endothelial cells.

PubMed

Muzaffar, Saima; Shukla, Nilima; Srivastava, Amit; Angelini, Gianni D; Jeremy, Jamie Y

2005-09-01

Acute respiratory distress syndrome (ARDS) is associated with increased superoxide (O(2)(*-)) formation in the pulmonary vasculature and negation of the bioavailability of nitric oxide (NO). Since NO inhibits NADPH oxidase expression through a cyclic GMP-mediated mechanism, sildenafil, a type V phosphodiesterase inhibitor, may be therapeutically effective in ARDS through an augmentation of NO-mediated inhibition of NADPH oxidase. Therefore, the effect of sildenafil citrate and NO-donating sildenafil (NCX 911) on O(2)(*-) formation and gp91(phox) (active catalytic subunit of NADPH oxidase) expression was investigated in cultured porcine pulmonary artery endothelial cells (PAECs). PAECs were incubated with 10 nM TXA(2) analogue, 9,11-dideoxy-9alpha,11alpha-methanoepoxy-prostaglandin F(2alpha) (U46619) (+/-sildenafil or NCX 911), for 16 h and O(2)(*-) formation measured spectrophometrically and gp91(phox) using Western blotting. The role of the NO-cGMP axis was studied using morpholinosydnonimine hydrochloride (SIN-1), the diethylamine/NO complex (DETA-NONOate), the guanylyl cyclase inhibitor, 1H-{1,2,4}oxadiazolo{4,3-a}quinoxalin-1-one (ODQ), and the protein kinase G inhibitor, 8-bromoguanosine-3',5'-cyclic monophosphorothioate, Rp-isomer (Rp-8-Br-cGMPS). NO release was studied using a fluorescence assay and O(2)(*-)-NO interactions by measuring nitrites. After a 16-h incubation with 10 nM U46619, both NCX 911 and sildenafil elicited a concentration-dependent inhibition of O(2)(*-) formation and gp91(phox) expression, NCX 911 being more potent (IC(50); 0.26 nM) than sildenafil citrate (IC(50); 1.85 nM). These inhibitory effects were reversed by 1 microM ODQ and 10 microM Rp-8-Br-cGMPS. NCX 911 stimulated the formation of cGMP in PAECs and generated NO in a cell-free system to a greater degree than sildenafil citrate. The inhibitory effect of sildenafil was augmented by 1 muM SIN-1 and blocked partially by the eNOS inhibitor 10 microM N(5)-(1-iminoethyl)-ornithine (L-NIO). Acutely, sildenafil and NCX 911 also inhibited O(2)(*-) formation, again blocked by 1 microM ODQ. NCX 911 reacted with O(2)(*-) generated by xanthine oxidase, an effect that was inhibited by superoxide dismutase (500 U ml(-1)). Since O(2)(*-) formation plays contributory role in ARDS, both sildenafil citrate and NCX 911 may be indicated for treating ARDS through suppression of NADPH oxidase expression and therefore of O(2)(*-) formation and preservation of NO bioavailability.

Crystal structures of monoamine oxidase B in complex with four inhibitors of the N-propargylaminoindan class.

PubMed

Binda, Claudia; Hubálek, Frantisek; Li, Min; Herzig, Yaacov; Sterling, Jeffrey; Edmondson, Dale E; Mattevi, Andrea

2004-03-25

Monoamine oxidase B (MAO B) is an outer mitochondrial membrane enzyme that catalyzes the oxidation of arylalkylamine neurotransmitters. The crystal structures of MAO B in complex with four of the N-propargylaminoindan class of MAO covalent inhibitors (rasagiline, N-propargyl-1(S)-aminoindan, 6-hydroxy-N-propargyl-1(R)-aminoindan, and N-methyl-N-propargyl-1(R)-aminoindan) have been determined at a resolution of better than 2.1 A. Rasagiline, 6-hydroxy-N-propargyl-1(R)-aminoindan, and N-methyl-N-propargyl-1(R)-aminoindan adopt essentially the same conformation with the extended propargyl chain covalently bound to the flavin and the indan ring located in the rear of the substrate cavity. N-Propargyl-1(S)-aminoindan binds with the indan ring in a flipped conformation with respect to the other inhibitors, which causes a slight movement of the Tyr326 side chain. Four ordered water molecules are an integral part of the active site and establish H-bond interactions to the inhibitor atoms. These structural studies may guide future drug design to improve selectivity and efficacy by introducing appropriate substituents on the rasagiline molecular scaffold.

Activation of TRPM2 and TRPV1 Channels in Dorsal Root Ganglion by NADPH Oxidase and Protein Kinase C Molecular Pathways: a Patch Clamp Study.

PubMed

Nazıroğlu, Mustafa

2017-03-01

Despite considerable research, the mechanisms of neuropathic pain induced by excessive oxidative stress production and overload calcium ion (Ca 2+ ) entry in dorsal root ganglion (DRG) remain substantially unidentified. The transient receptor potential melastatin 2 (TRPM2) and vanilloid 1 (TRPV1) channels are activated with different stimuli including oxidative stress. TRPM2 and TRPV1 have been shown to be involved in induction of neuropathic pain. However, the activation mechanisms of TRPM2 and TRPV1 via NADPH oxidase and protein kinase C (PKC) pathways are poorly understood. In this study, I investigated the roles of NADPH oxidase and PKC on Ca 2+ entry through TRPM2 and TRPV1 channels in in vitro DRG neurons of rats. Rat DRG neurons were used in whole-cell patch clamp experiments. The H 2 O 2 -induced TRPM2 current densities were decreased by N-(p-amylcinnamoyl)anthranilic acid (ACA), and dose-dependent capsaicin (CAP) and H 2 O 2 -induced TRPV1 currents were inhibited by capsazepine (CPZ). The TRPV1 channel is activated in the DRG neurons by 0.01 mM capsaicin but not 0.001 mM or 0.05 mM capsaicin. TRPM2 and TRPV1 currents were increased by the PKC activator, phorbol myristate acetate (PMA), although the currents were decreased by ACA, CPZ, and the PKC inhibitor, bisindolylmaleimide I (BIM). Both channel currents were further increased by PMA + H 2 O 2 as compared to H 2 O 2 only. In the combined presence of PMA + BIM, no TRPM2 or TRPV1 currents were observed. The CAP and H 2 O 2 -induced TRPM2 current densities were also decreased by the NADPH oxidase inhibitors apocynin and N-Acetylcysteine. In conclusion, these results demonstrate a protective role for NADPH oxidase and PKC inhibitors on Ca 2+ entry through TRPM2 and TRPV1 channels in DRG neurons. Since excessive oxidative stress production and Ca 2+ entry are implicated in the pathophysiology of neuropathic pain, the findings may be relevant to the etiology and treatment of neuropathology in DRG neurons.

Identification of crypto- and neochlorogenic lactones as potent xanthine oxidase inhibitors in roasted coffee beans.

PubMed

Honda, Sari; Miura, Yukari; Masuda, Akiko; Masuda, Toshiya

2014-01-01

Xanthine oxidase (XO) inhibitory activity has been found in boiling water extracts from roasted coffee beans. Therefore, assay-guided purification of the extracts was performed using size-exclusion column chromatography, and subsequently with reversed phase HPLC to afford lactone derivatives of chlorogenic acids. Among the tested lactones, crypto- and neochlorogenic lactones showed potent XO inhibitory activities compared with three major chlorogenic acids found in coffee beans. These XO inhibitory lactones may ameliorate gout and hyperuricemia in humans who drink coffee.

Survival Signaling in Prostate Cancer: Role of Androgen Receptor and Integrins in Regulating Survival

DTIC Science & Technology

2010-01-01

basal cells with the monoamine oxidase A inhibitor clorgyline, 1,25-dihydroxyvitamin D3, all-trans retinoic acid and TGF-1 induced AR expression and...41, 85-97. Zhao, H., Nolley, R., Chen, Z., Reese, S. W. and Peehl, D. M. (2008). Inhibition of monoamine oxidase A promotes secretory differentiation...Confluent primary human prostate epithelial cell cultures were treated with KGF and androgen (DHT). After two weeks, a suprabasal cell layer formed in

The first mammalian aldehyde oxidase crystal structure: insights into substrate specificity.

PubMed

Coelho, Catarina; Mahro, Martin; Trincão, José; Carvalho, Alexandra T P; Ramos, Maria João; Terao, Mineko; Garattini, Enrico; Leimkühler, Silke; Romão, Maria João

2012-11-23

Aldehyde oxidases have pharmacological relevance, and AOX3 is the major drug-metabolizing enzyme in rodents. The crystal structure of mouse AOX3 with kinetics and molecular docking studies provides insights into its enzymatic characteristics. Differences in substrate and inhibitor specificities can be rationalized by comparing the AOX3 and xanthine oxidase structures. The first aldehyde oxidase structure represents a major advance for drug design and mechanistic studies. Aldehyde oxidases (AOXs) are homodimeric proteins belonging to the xanthine oxidase family of molybdenum-containing enzymes. Each 150-kDa monomer contains a FAD redox cofactor, two spectroscopically distinct [2Fe-2S] clusters, and a molybdenum cofactor located within the protein active site. AOXs are characterized by broad range substrate specificity, oxidizing different aldehydes and aromatic N-heterocycles. Despite increasing recognition of its role in the metabolism of drugs and xenobiotics, the physiological function of the protein is still largely unknown. We have crystallized and solved the crystal structure of mouse liver aldehyde oxidase 3 to 2.9 Å. This is the first mammalian AOX whose structure has been solved. The structure provides important insights into the protein active center and further evidence on the catalytic differences characterizing AOX and xanthine oxidoreductase. The mouse liver aldehyde oxidase 3 three-dimensional structure combined with kinetic, mutagenesis data, molecular docking, and molecular dynamics studies make a decisive contribution to understand the molecular basis of its rather broad substrate specificity.

Rac1 Is Required for Cardiomyocyte Apoptosis During Hyperglycemia

PubMed Central

Shen, E.; Li, Yanwen; Li, Ying; Shan, Limei; Zhu, Huaqing; Feng, Qingping; Arnold, J. Malcolm O.; Peng, Tianqing

2009-01-01

OBJECTIVE Hyperglycemia induces reactive oxygen species (ROS) and apoptosis in cardiomyocytes, which contributes to diabetic cardiomyopathy. The present study was to investigate the role of Rac1 in ROS production and cardiomyocyte apoptosis during hyperglycemia. RESEARCH DESIGN AND METHODS Mice with cardiomyocyte-specific Rac1 knockout (Rac1-ko) were generated. Hyperglycemia was induced in Rac1-ko mice and their wild-type littermates by injection of streptozotocin (STZ). In cultured adult rat cardiomyocytes, apoptosis was induced by high glucose. RESULTS The results showed a mouse model of STZ-induced diabetes, 7 days of hyperglycemia-upregulated Rac1 and NADPH oxidase activation, elevated ROS production, and induced apoptosis in the heart. These effects of hyperglycemia were significantly decreased in Rac1-ko mice or wild-type mice treated with apocynin. Interestingly, deficiency of Rac1 or apocynin treatment significantly reduced hyperglycemia-induced mitochondrial ROS production in the heart. Deficiency of Rac1 also attenuated myocardial dysfunction after 2 months of STZ injection. In cultured cardiomyocytes, high glucose upregulated Rac1 and NADPH oxidase activity and induced apoptotic cell death, which were blocked by overexpression of a dominant negative mutant of Rac1, knockdown of gp91phox or p47phox, or NADPH oxidase inhibitor. In type 2 diabetic db/db mice, administration of Rac1 inhibitor, NSC23766, significantly inhibited NADPH oxidase activity and apoptosis and slightly improved myocardial function. CONCLUSIONS Rac1 is pivotal in hyperglycemia-induced apoptosis in cardiomyocytes. The role of Rac1 is mediated through NADPH oxidase activation and associated with mitochondrial ROS generation. Our study suggests that Rac1 may serve as a potential therapeutic target for cardiac complications of diabetes. PMID:19592621

Controlling of N-alkylpolyamine analogue metabolism by selective deuteration.

PubMed

Ucal, Sebahat; Häkkinen, Merja R; Alanne, Aino-Liisa; Alhonen, Leena; Vepsäläinen, Jouko; Keinänen, Tuomo A; Hyvönen, Mervi T

2018-02-14

Replacing protium with deuterium is an efficient method to modulate drug metabolism. N -alkylated polyamine analogues are polyamine antimetabolites with proven anticancer efficacy. We have characterized earlier the preferred metabolic routes of N 1 , N 12 -diethylspermine (DESpm), N 1 -benzyl- N 12 -ethylspermine (BnEtSpm) and N 1 , N 12 -dibenzylspermine (DBSpm) by human recombinant spermine oxidase (SMOX) and acetylpolyamine oxidase (APAO). Here, we studied the above analogues, their variably deuterated counterparts and their metabolites as substrates and inhibitors of APAO, SMOX, semicarbazide-sensitive amine oxidase (SSAO), diamine oxidase (DAO) and monoamine oxidases. We found that targeted deuteration efficiently redirected the preferable cleavage site and suppressed reaction rate by APAO and SMOX in vitro We found a three- to six-fold decline in V max with moderate variable effect on K m when deuterium was located at the preferred hydrogen abstraction site of the analogue. We also found some of the metabolites to be potent inhibitors of DAO and SSAO. Surprisingly, analogue deuteration did not markedly alter the anti-proliferative efficacy of the drugs in DU145 prostate cancer cells, while in mouse embryonic fibroblasts, which had higher basal APAO and SMOX activities, moderate effect was observed. Interestingly, the anti-proliferative efficacy of the analogues did not correlate with their ability to suppress polyamine biosynthetic enzymes, induce spermidine/spermine- N 1 -acetyltransferase or deplete intracellular polyamine levels, but correlated with their ability to induce SMOX. Our data show that selective deuteration of N -alkyl polyamine analogues enables metabolic switching, offering the means for selective generation of bioactive metabolites inhibiting, e.g. SSAO and DAO, thus setting a novel basis for in vivo studies of this class of analogues. © 2018 The Author(s). Published by Portland Press Limited on behalf of the Biochemical Society.

The Role of Aldehyde Oxidase and Xanthine Oxidase in the Biotransformation of a Novel Negative Allosteric Modulator of Metabotropic Glutamate Receptor Subtype 5

PubMed Central

Morrison, Ryan D.; Blobaum, Anna L.; Byers, Frank W.; Santomango, Tammy S.; Bridges, Thomas M.; Stec, Donald; Brewer, Katrina A.; Sanchez-Ponce, Raymundo; Corlew, Melany M.; Rush, Roger; Felts, Andrew S.; Manka, Jason; Bates, Brittney S.; Venable, Daryl F.; Rodriguez, Alice L.; Jones, Carrie K.; Niswender, Colleen M.; Conn, P. Jeffrey; Lindsley, Craig W.; Emmitte, Kyle A.

2012-01-01

Negative allosteric modulation (NAM) of metabotropic glutamate receptor subtype 5 (mGlu5) represents a therapeutic strategy for the treatment of childhood developmental disorders, such as fragile X syndrome and autism. VU0409106 emerged as a lead compound within a biaryl ether series, displaying potent and selective inhibition of mGlu5. Despite its high clearance and short half-life, VU0409106 demonstrated efficacy in rodent models of anxiety after extravascular administration. However, lack of a consistent correlation in rat between in vitro hepatic clearance and in vivo plasma clearance for the biaryl ether series prompted an investigation into the biotransformation of VU0409106 using hepatic subcellular fractions. An in vitro appraisal in rat, monkey, and human liver S9 fractions indicated that the principal pathway was NADPH-independent oxidation to metabolite M1 (+16 Da). Both raloxifene (aldehyde oxidase inhibitor) and allopurinol (xanthine oxidase inhibitor) attenuated the formation of M1, thus implicating the contribution of both molybdenum hydroxylases in the biotransformation of VU0409106. The use of 18O-labeled water in the S9 experiments confirmed the hydroxylase mechanism proposed, because 18O was incorporated into M1 (+18 Da) as well as in a secondary metabolite (M2; +36 Da), the formation of which was exclusively xanthine oxidase-mediated. This unusual dual and sequential hydroxylase metabolism was confirmed in liver S9 and hepatocytes of multiple species and correlated with in vivo data because M1 and M2 were the principal metabolites detected in rats administered VU0409106. An in vitro-in vivo correlation of predicted hepatic and plasma clearance was subsequently established for VU0409106 in rats and nonhuman primates. PMID:22711749

Glitazones inhibit human monoamine oxidase but their anti-inflammatory actions are not mediated by VAP-1/semicarbazide-sensitive amine oxidase inhibition.

PubMed

Carpéné, Christian; Bizou, Mathilde; Tréguer, Karine; Hasnaoui, Mounia; Grès, Sandra

2015-09-01

Glitazones are peroxisome proliferator-activated receptor gamma (PPARγ) agonists widely used as antidiabetic drugs also known as thiazolidinediones. Most of them exert other effects such as anti-inflammatory actions via mechanisms supposed to be independent from PPARγ activation (e.g., decreased plasma monocyte chemoattractant protein-1 (MCP-1) levels). Recently, pioglitazone has been shown to inhibit the B form of monoamine oxidase (MAO) in mouse, while rosiglitazone and troglitazone were described as non-covalent inhibitors of both human MAO A and MAO B. Since molecules interacting with MAO might also inhibit semicarbazide-sensitive amine oxidase (SSAO), known as vascular adhesion protein-1 (VAP-1), and since VAP-1/SSAO inhibitors exhibit anti-inflammatory activity, our aim was to elucidate whether VAP-1/SSAO inhibition could be a mechanism involved in the anti-inflammatory behaviour of glitazones. To this aim, MAO and SSAO activities were measured in human subcutaneous adipose tissue biopsies obtained from overweight women undergoing plastic surgery. The production of hydrogen peroxide, an end-product of amine oxidase activity, was determined in tissue homogenates using a fluorometric method. The oxidation of 1 mM tyramine was inhibited by pargyline and almost resistant to semicarbazide, therefore predominantly MAO-dependent. Rosiglitazone was more potent than pioglitazone in inhibiting tyramine oxidation. By contrast, benzylamine oxidation was only abolished by semicarbazide: hence SSAO-mediated. Pioglitazone hampered SSAO activity only when tested at 1 mM while rosiglitazone was inefficient. However, rosiglitazone exhibited anti-inflammatory activity in human adipocytes by limiting MCP-1 expression. Our observations rule out any involvement of VAP-1/SSAO inhibition and subsequent limitation of leukocyte extravasation in the anti-inflammatory action of glitazones.

Silica-Immobilized Enzyme Reactors (Postprint)

DTIC Science & Technology

2007-09-01

mode of action of drugs such as aspirin and ibuprofen .[61] Serotonin reuptake inhibitors and monoamine oxidase inhibitors can function as...immobilizing PGA onto chromatography supports and using the enantiomeric selectivity of the enzyme to resolve racemic mixtures.[100] Immobilization onto...column. J. Chroma- togr. B. Biomed. Sci. Appl. 2001, 753, 375–383. 37. Jadaud, P.; Wainer, I.W. The stereochemical resolution of the enantiomers of

Cloning and Analysis of the Alternative Oxidase Gene of Neurospora Crassa

PubMed Central

Li, Q.; Ritzel, R. G.; McLean, LLT.; McIntosh, L.; Ko, T.; Bertrand, H.; Nargang, F. E.

1996-01-01

Mitochondria of Neurospora crassa contain a cyanide-resistant alternative respiratory pathway in addition to the cytochrome pathway. The alternative oxidase is present only when electron flow through the cytochrome chain is restricted. Both genomic and cDNA copies for the alternative oxidase gene have been isolated and analyzed. The sequence of the predicted protein is homologous to that of other species. The mRNA for the alternative oxidase is scarce in wild-type cultures grown under normal conditions, but it is abundant in cultures grown in the presence of chloramphenicol, an inhibitor of mitochondrial protein synthesis, or in mutants deficient in mitochondrial cytochromes. Thus, induction of alternative oxidase appears to be at the transcriptional level. Restriction fragment length polymorphism mapping of the isolated gene demonstrated that it is located in a position corresponding to the aod-1 locus. Sequence analysis of mutant aod-1 alleles reveals mutations affecting the coding sequence of the alternative oxidase. The level of aod-1 mRNA in an aod-2 mutant strain that had been grown in the presence of chloramphenicol was reduced several fold relative to wild-type, supporting the hypothesis that the product of aod-2 is required for optimal expression of aod-1. PMID:8770590

Validation of tautomeric and protomeric binding modes by free energy calculations. A case study for the structure based optimization of D-amino acid oxidase inhibitors.

PubMed

Orgován, Zoltán; Ferenczy, György G; Steinbrecher, Thomas; Szilágyi, Bence; Bajusz, Dávid; Keserű, György M

2018-02-01

Optimization of fragment size D-amino acid oxidase (DAAO) inhibitors was investigated using a combination of computational and experimental methods. Retrospective free energy perturbation (FEP) calculations were performed for benzo[d]isoxazole derivatives, a series of known inhibitors with two potential binding modes derived from X-ray structures of other DAAO inhibitors. The good agreement between experimental and computed binding free energies in only one of the hypothesized binding modes strongly support this bioactive conformation. Then, a series of 1-H-indazol-3-ol derivatives formerly not described as DAAO inhibitors was investigated. Binding geometries could be reliably identified by structural similarity to benzo[d]isoxazole and other well characterized series and FEP calculations were performed for several tautomers of the deprotonated and protonated compounds since all these forms are potentially present owing to the experimental pKa values of representative compounds in the series. Deprotonated compounds are proposed to be the most important bound species owing to the significantly better agreement between their calculated and measured affinities compared to the protonated forms. FEP calculations were also used for the prediction of the affinities of compounds not previously tested as DAAO inhibitors and for a comparative structure-activity relationship study of the benzo[d]isoxazole and indazole series. Selected indazole derivatives were synthesized and their measured binding affinity towards DAAO was in good agreement with FEP predictions.

Validation of tautomeric and protomeric binding modes by free energy calculations. A case study for the structure based optimization of d-amino acid oxidase inhibitors

NASA Astrophysics Data System (ADS)

Orgován, Zoltán; Ferenczy, György G.; Steinbrecher, Thomas; Szilágyi, Bence; Bajusz, Dávid; Keserű, György M.

2018-02-01

Optimization of fragment size d-amino acid oxidase (DAAO) inhibitors was investigated using a combination of computational and experimental methods. Retrospective free energy perturbation (FEP) calculations were performed for benzo[d]isoxazole derivatives, a series of known inhibitors with two potential binding modes derived from X-ray structures of other DAAO inhibitors. The good agreement between experimental and computed binding free energies in only one of the hypothesized binding modes strongly support this bioactive conformation. Then, a series of 1-H-indazol-3-ol derivatives formerly not described as DAAO inhibitors was investigated. Binding geometries could be reliably identified by structural similarity to benzo[d]isoxazole and other well characterized series and FEP calculations were performed for several tautomers of the deprotonated and protonated compounds since all these forms are potentially present owing to the experimental pKa values of representative compounds in the series. Deprotonated compounds are proposed to be the most important bound species owing to the significantly better agreement between their calculated and measured affinities compared to the protonated forms. FEP calculations were also used for the prediction of the affinities of compounds not previously tested as DAAO inhibitors and for a comparative structure-activity relationship study of the benzo[d]isoxazole and indazole series. Selected indazole derivatives were synthesized and their measured binding affinity towards DAAO was in good agreement with FEP predictions.

Monoamine oxidase inhibitory activities of heterocyclic chalcones.

PubMed

Minders, Corné; Petzer, Jacobus P; Petzer, Anél; Lourens, Anna C U

2015-11-15

Studies have shown that natural and synthetic chalcones (1,3-diphenyl-2-propen-1-ones) possess monoamine oxidase (MAO) inhibition activities. Of particular importance to the present study is a report that a series of furanochalcones acts as MAO-B selective inhibitors. Since the effect of heterocyclic substitution, other than furan (and more recently thiophene, piperidine and quinoline) on the MAO inhibitory properties of the chalcone scaffold remains unexplored, the aim of this study was to synthesise and evaluate further heterocyclic chalcone analogues as inhibitors of the human MAOs. For this purpose, heterocyclic chalcone analogues that incorporate pyrrole, 5-methylthiophene, 5-chlorothiophene and 6-methoxypyridine substitution were examined. Seven of the nine synthesised compounds exhibited IC50 values <1 μM for the inhibition of MAO-B, with all compounds exhibiting higher affinities for MAO-B compared to the MAO-A isoform. The most potent MAO-B inhibitor (4h) displays an IC50 value of 0.067 μM while the most potent MAO-A inhibitor (4e) exhibits an IC50 value of 3.81 μM. It was further established that selected heterocyclic chalcones are reversible and competitive MAO inhibitors. 4h, however, may exhibit tight-binding to MAO-B, a property linked to its thiophene moiety. We conclude that high potency chalcones such as 4h represent suitable leads for the development of MAO-B inhibitors for the treatment of Parkinson's disease and possibly other neurodegenerative disorders. Copyright © 2015 Elsevier Ltd. All rights reserved.

Monoamine oxidase: isoforms and inhibitors in Parkinson's disease and depressive illness

PubMed Central

Youdim, Moussa B H; Bakhle, Y S

2006-01-01

A few years after the foundation of the British Pharmacological Society, monoamine oxidase (MAO) was recognized as an enzyme of crucial interest to pharmacologists because it catalyzed the major inactivation pathway for the catecholamine neurotransmitters, noradrenaline, adrenaline and dopamine (and, later, 5-hydroxytryptamine, as well). Within the next decade, the therapeutic value of inhibitors of MAO in the treatment of depressive illness was established. Although this first clinical use exposed serious side effects, pharmacological interest in, and investigation of, MAO continued, resulting in the characterization of two isoforms, MAO-A and -B, and isoform-selective inhibitors. Selective inhibitors of MAO-B have found a therapeutic role in the treatment of Parkinson's disease and further developments have provided reversible inhibitors of MAO-A, which offer antidepressant activity without the serious side effects of the earlier inhibitors. Clinical observation and subsequent pharmacological analysis have also generated the concept of neuroprotection, reflecting the possibility of slowing, halting and maybe reversing, neurodegeneration in Parkinson's or Alzheimer's diseases. Increased levels of oxidative stress in the brain may be critical for the initiation and progress of neurodegeneration and selective inhibition of brain MAO could contribute importantly to lowering such stress. There are complex interactions between free iron levels in brain and MAO, which may have practical outcomes for depressive disorders. These aspects of MAO and its inhibition and some indication of how this important area of pharmacology and therapeutics might develop in the future are summarized in this review. PMID:16402116

8-Aryl- and alkyloxycaffeine analogues as inhibitors of monoamine oxidase.

PubMed

Strydom, Belinda; Bergh, Jacobus J; Petzer, Jacobus P

2011-08-01

Recently it was reported that a series of 8-benzyloxycaffeine analogues are potent reversible inhibitors of human monoamine oxidase (MAO) A and B. In an attempt to discover additional C8 oxy substituents of caffeine that lead to potent MAO inhibition, a series of related 8-aryl- and alkyloxycaffeine analogues were synthesized and their MAO-A and -B inhibition potencies were compared to those of the 8-benzyloxycaffeines. The results document that while the 8-substituted-oxycaffeine analogues inhibited both human MAO isoforms, they displayed a high degree of selectivity for MAO-B. 8-(3-Phenylpropoxy)caffeine, 8-(2-phenoxyethoxy)caffeine and 8-[(5-methylhexyl)oxy]caffeine were found to be the especially potent MAO-B inhibitors with IC(50) values ranging from 0.38 to 0.62 μM. These inhibitors are therefore 2.5-4.6 fold more potent MAO-B inhibitors than is 8-benzyloxycaffeine (IC(50) = 1.77 μM). It is also demonstrated that, analogous to 8-benzyloxycaffeine, halogen substitution on the phenyl ring of the C8 substituent significantly enhances MAO binding affinity. For example, the most potent MAO-B inhibitor of the present series is 8-[2-(4-bromophenoxy)ethoxy]caffeine with an IC(50) value of 0.166 μM. This study also reports possible binding orientations of selected oxy caffeines within the active site cavities of MAO-A and MAO-B. Copyright © 2011 Elsevier Masson SAS. All rights reserved.

Solid-phase synthesis and insights into structure-activity relationships of safinamide analogues as potent and selective inhibitors of type B monoamine oxidase.

PubMed

Leonetti, Francesco; Capaldi, Carmelida; Pisani, Leonardo; Nicolotti, Orazio; Muncipinto, Giovanni; Stefanachi, Angela; Cellamare, Saverio; Caccia, Carla; Carotti, Angelo

2007-10-04

Safinamide, (S)-N2-{4-[(3-fluorobenzyl)oxy]benzyl}alaninamide methanesulfonate, which is in phase III clinical trials as an anti-Parkinson drug, and a library of alkanamidic analogues were prepared through an expeditious solid-phase synthesis and evaluated for their monoamine oxidase B (MAO-B) and monoamine oxidase A (MAO-A) inhibitory activity and selectivity. (S)-3-Chlorobenzyloxyalaninamide (8) and (S)-3-chlorobenzyloxyserinamide (13) derivatives proved to be more potent MAO-B inhibitors than safinamide (IC50 = 33 and 43 nM, respectively, vs 98 nM) but with a lower MAO-B selectivity (SI = 3455 and 1967, respectively, vs 5918). The highest MAO-B inhibitory potency (IC50 = 17 nM) and a good selectivity (SI = 2941) were displayed by (R)-21, a tetrahydroisoquinoline analogue of safinamide. Structure-affinity relationships and docking simulations pointed out strong negative steric effects of alpha-aminoamide side chains and para substituents of the benzyloxy groups and favorable hydrophobic interactions of meta substituents. The significantly diverse MAO-B affinities of a number of R and S alpha-aminoamide enantiomers, including the two rigid analogues (21) of safinamide, indicated likely enantioselective interactions at the enzymatic binding sites.

Structure-activity relationships of diphenyl-ether as protoporphyrinogen oxidase inhibitors: insights from computational simulations

NASA Astrophysics Data System (ADS)

Hao, Ge-Fei; Tan, Ying; Yu, Ning-Xi; Yang, Guang-Fu

2011-03-01

Protoporphyrinogen oxidase (PPO, EC 1.3.3.4), which has been identified as a significant target for a great family of herbicides with diverse chemical structures, is the last common enzyme responsible for the seventh step in the biosynthetic pathway to heme and chlorophyll. Among the existing PPO inhibitors, diphenyl-ether is the first commercial family of PPO inhibitors and used as agriculture herbicides for decades. Most importantly, diphenyl-ether inhibitors have been found recently to possess the potential in Photodynamic therapy (PDT) to treat cancer. Herein, molecular dynamics simulations, approximate free energy calculations and hydrogen bond energy calculations were integrated together to uncover the structure-activity relationships of this type of PPO inhibitors. The calculated binding free energies are correlated very well with the values derived from the experimental k i data. According to the established computational models and the results of approximate free energy calculation, the substitution effects at different position were rationalized from the view of binding free energy. Some outlier ( e.g. LS) in traditional QSAR study can also be explained reasonably. In addition, the hydrogen bond energy calculation and interaction analysis results indicated that the carbonyl oxygen on position-9 and the NO2 group at position-8 are both vital for the electrostatic interaction with Arg98, which made a great contribution to the binding free energy. These insights from computational simulations are not only helpful for understanding the molecular mechanism of PPO-inhibitor interactions, but also beneficial to the future rational design of novel promising PPO inhibitors.

Xanthine oxidase inhibitors beyond allopurinol and febuxostat; an overview and selection of potential leads based on in silico calculated physico-chemical properties, predicted pharmacokinetics and toxicity.

PubMed

Šmelcerović, Andrija; Tomović, Katarina; Šmelcerović, Žaklina; Petronijević, Živomir; Kocić, Gordana; Tomašič, Tihomir; Jakopin, Žiga; Anderluh, Marko

2017-07-28

Xanthine oxidase (XO), a versatile metalloflavoprotein enzyme, catalyzes the oxidative hydroxylation of hypoxanthine and xanthine to uric acid in purine catabolism while simultaneously producing reactive oxygen species. Both lead to the gout-causing hyperuricemia and oxidative damage of the tissues where overactivity of XO is present. Over the past years, significant progress and efforts towards the discovery and development of new XO inhibitors have been made and we believe that not only experts in the field, but also general readership would benefit from a review that addresses this topic. Accordingly, the aim of this article was to overview and select the most potent recently reported XO inhibitors and to compare their structures, mechanisms of action, potency and effectiveness of their inhibitory activity, in silico calculated physico-chemical properties as well as predicted pharmacokinetics and toxicity. Derivatives of imidazole, 1,3-thiazole and pyrimidine proved to be more potent than febuxostat while also displaying/possessing favorable predicted physico-chemical, pharmacokinetic and toxicological properties. Although being structurally similar to febuxostat, these optimized inhibitors bear some structural freshness and could be adopted as hits for hit-to-lead development and further evaluation by in vivo studies towards novel drug candidates, and represent valuable model structures for design of novel XO inhibitors. Copyright © 2017 Elsevier Masson SAS. All rights reserved.

Exploring the structural basis of the selective inhibition of monoamine oxidase A by dicarbonitrile aminoheterocycles: role of Asn181 and Ile335 validated by spectroscopic and computational studies.

PubMed

Juárez-Jiménez, Jordi; Mendes, Eduarda; Galdeano, Carles; Martins, Carla; Silva, Daniel B; Marco-Contelles, José; do Carmo Carreiras, Maria; Luque, F Javier; Ramsay, Rona R

2014-02-01

Since cyanide potentiates the inhibitory activity of several monoamine oxidase (MAO) inhibitors, a series of carbonitrile-containing aminoheterocycles was examined to explore the role of nitriles in determining the inhibitory activity against MAO. Dicarbonitrile aminofurans were found to be potent, selective inhibitors against MAO A. The origin of the MAO A selectivity was identified by combining spectroscopic and computational methods. Spectroscopic changes induced in MAO A by mono- and dicarbonitrile inhibitors were different, providing experimental evidence for distinct binding modes to the enzyme. Similar differences were also found between the binding of dicarbonitrile compounds to MAO A and to MAO B. Stabilization of the flavin anionic semiquinone by monocarbonitrile compounds, but destabilization by dicarbonitriles, provided further support to the distinct binding modes of these compounds and their interaction with the flavin ring. Molecular modeling studies supported the role played by the nitrile and amino groups in anchoring the inhibitor to the binding cavity. In particular, the results highlight the role of Asn181 and Ile335 in assisting the interaction of the nitrile-containing aminofuran ring. The network of interactions afforded by the specific attachment of these functional groups provides useful guidelines for the design of selective, reversible MAO A inhibitors. Copyright © 2013 Elsevier B.V. All rights reserved.

3,4-Dihydroxyphenylethanol (Hydroxytyrosol) Mitigates the Increase in Spontaneous Oxidation of Dopamine during Monoamine Oxidase Inhibition in PC12 Cells

PubMed Central

Goldstein, David S.; Jinsmaa, Yunden; Sullivan, Patti; Holmes, Courtney; Kopin, Irwin J.; Sharabi, Yehonatan

2016-01-01

The catecholaldehyde hypothesis predicts that monoamine oxidase (MAO) inhibition should slow the progression of Parkinson’s disease, by decreasing production of the autotoxic dopamine metabolite 3,4-dihydroxyphenylacetaldehyde (DOPAL). Inhibiting MAO, however, diverts the fate of cytoplasmic dopamine toward potentially harmful spontaneous oxidation products, indicated by increased 5-S-cysteinyl-dopamine (Cys-DA) levels. 3,4-Dihydroxyphenylethanol (hydroxytyrosol) is an abundant anti-oxidant phenol in constituents of the Mediterranean diet. Whether hydroxytyrosol alters enzymatic or spontaneous oxidation of dopamine has been unknown. Rat pheochromocytoma PC12 cells were incubated with hydroxytyrosol (10 μM, 180 minutes) alone or with the MAO-A inhibitor clorgyline (1 nM) or the MAO-B inhibitors rasagiline or selegiline (0.5 μM). Hydroxytyrosol decreased levels of DOPAL by 30% and Cys-DA by 49% (p<0.0001 each). Co-incubation with hydroxytyrosol prevented the increases in Cys-DA seen with all 3 MAO inhibitors. Hydroxytyrosol therefore inhibits both enzymatic and spontaneous oxidation of endogenous dopamine and mitigates the increase in spontaneous oxidation during MAO inhibition. PMID:27220335

4,6-Diaryl/heteroarylpyrimidin-2(1H)-ones as a new class of xanthine oxidase inhibitors.

PubMed

Shukla, Shiwani; Kumar, Dinesh; Ojha, Ritu; Gupta, Manish K; Nepali, Kunal; Bedi, Preet M S

2014-07-01

A series of 4,6-diaryl/heteroarylpyrimidones was synthesized employing silica-supported fluoroboric acid under solvent-free conditions in a microwave reactor. The catalytic influence of HBF4-SiO2 was investigated in detail to optimize the reaction conditions. The synthesized compounds were evaluated for in vitro xanthine oxidase (XO) inhibitory activity for the first time. Structure-activity relationship analyses are also presented. Among the synthesized compounds, VA-5, -9, -10, -12, -22, -23, and -25 were the active inhibitors with IC50 values ranging from 6.45 to 13.46 µM. Compound VA-25 with a pyridinyl ring as ring A and a thiophenyl ring as ring B emerged as the most potent XO inhibitor (IC50 = 6.45 µM) in comparison to allopurinol (IC50 = 12.24 µM). Some of the important interactions of VA-25 with the amino acid residues of the active site of XO were figured out by molecular modeling studies. © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Structure-Based Design and Optimization of Multitarget-Directed 2H-Chromen-2-one Derivatives as Potent Inhibitors of Monoamine Oxidase B and Cholinesterases.

PubMed

Farina, Roberta; Pisani, Leonardo; Catto, Marco; Nicolotti, Orazio; Gadaleta, Domenico; Denora, Nunzio; Soto-Otero, Ramon; Mendez-Alvarez, Estefania; Passos, Carolina S; Muncipinto, Giovanni; Altomare, Cosimo D; Nurisso, Alessandra; Carrupt, Pierre-Alain; Carotti, Angelo

2015-07-23

The multifactorial nature of Alzheimer's disease calls for the development of multitarget agents addressing key pathogenic processes. To this end, by following a docking-assisted hybridization strategy, a number of aminocoumarins were designed, prepared, and tested as monoamine oxidases (MAOs) and acetyl- and butyryl-cholinesterase (AChE and BChE) inhibitors. Highly flexible N-benzyl-N-alkyloxy coumarins 2-12 showed good inhibitory activities at MAO-B, AChE, and BChE but low selectivity. More rigid inhibitors, bearing meta- and para-xylyl linkers, displayed good inhibitory activities and high MAO-B selectivity. Compounds 21, 24, 37, and 39, the last two featuring an improved hydrophilic/lipophilic balance, exhibited excellent activity profiles with nanomolar inhibitory potency toward hMAO-B, high hMAO-B over hMAO-A selectivity and submicromolar potency at hAChE. Cell-based assays of BBB permeation, neurotoxicity, and neuroprotection supported the potential of compound 37 as a BBB-permeant neuroprotective agent against H2O2-induced oxidative stress with poor interaction as P-gp substrate and very low cytotoxicity.

The angiotensin II-AT1 receptor stimulates reactive oxygen species within the cell nucleus

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

Pendergrass, Karl D.; Gwathmey, TanYa M.; Michalek, Ryan D.

2009-06-26

We and others have reported significant expression of the Ang II Type 1 receptor (AT1R) on renal nuclei; thus, the present study assessed the functional pathways and distribution of the intracellular AT1R on isolated nuclei. Ang II (1 nM) stimulated DCF fluorescence, an intranuclear indicator of reactive oxygen species (ROS), while the AT1R antagonist losartan or the NADPH oxidase (NOX) inhibitor DPI abolished the increase in ROS. Dual labeling of nuclei with antibodies against nucleoporin 62 (Nup62) and AT1R or the NADPH oxidase isoform NOX4 revealed complete overlap of the Nup62 and AT1R (99%) by flow cytometry, while NOX4 wasmore » present on 65% of nuclei. Treatment of nuclei with a PKC agonist increased ROS while the PKC inhibitor GF109203X or PI3 kinase inhibitor LY294002 abolished Ang II stimulation of ROS. We conclude that the Ang II-AT1R-PKC axis may directly influence nuclear function within the kidney through a redox sensitive pathway.« less

Oligoamine analogues in combination with 2-difluoromethylornithine synergistically induce re-expression of aberrantly silenced tumour-suppressor genes

PubMed Central

Wu, Yu; Steinbergs, Nora; Murray-Stewart, Tracy; Marton, Laurence J.; Casero, Robert A.

2011-01-01

Epigenetic gene silencing is an important mechanism in the initiation and progression of cancer. Abnormal DNA CpG island hypermethylation and histone modifications are involved in aberrant silencing of tumour-suppressor genes. LSD1 (lysine-specific demethylase 1) was the first enzyme identified to specifically demethylate H3K4 (Lys4 of histone H3). Methylated H3K4 is an important mark associated with transcriptional activation. The flavin adenine dinucleotide-binding amine oxidase domain of LSD1 is homologous with two polyamine oxidases, SMO (spermine oxidase) and APAO (N1-acetylpolyamine oxidase). We have demonstrated previously that long-chain polyamine analogues, the oligoamines, are inhibitors of LSD1. In the present paper we report the synergistic effects of specific oligoamines in combination with DFMO (2-difluoromethylornithine), an inhibitor of ornithine decarboxylase, in human colorectal cancer cells. DFMO treatment depletes natural polyamines and increases the uptake of exogenous polyamines. The combination of oligoamines and DFMO results in a synergistic re-expression of aberrantly silenced tumour-suppressor genes, including SFRP2 (secreted frizzled-related protein 2), which encodes a Wnt signalling pathway antagonist and plays an anti-tumorigenic role in colorectal cancer. The treatment-induced re-expression of SFRP2 is associated with increased H3K4me2 (di-methyl H3K4) in the gene promoter. The combination of LSD1-inhibiting oligoamines and DFMO represents a novel approach to epigenetic therapy of cancer. PMID:22132744

The effects of monoamine oxidase inhibitors on the ejaculatory response induced by 5-methoxy-N,N-dimethyltryptamine in the rat.

PubMed Central

Rényi, L.

1986-01-01

The ejaculatory response and other components of the 5-hydroxytryptamine (5-HT) behavioural syndrome induced by 5-methoxy-N,N-dimethyltryptamine (5-MeODMT) (3 mg kg-1, i.p.) were studied following single and repeated treatment of rats with eight different monoamine oxidase (MAO) inhibitors. Single and repeated treatment with the 5-HT agonist 5-MeODMT, and with low doses of the potent releaser of 5-HT, p-chloroamphetamine (PCA) were also included in the study. Repeated but not single treatment with 5-MeODMT reduced strongly but reversibly the ejaculatory response and the behavioural responses. Repeated but not single treatment with the nonselective and irreversible MAO inhibitors nialamide and pargyline reduced markedly the ejaculatory response but only slightly the 5-HT behavioural responses. Repeated treatment with the irreversible MAO-B inhibitor (-)-deprenyl, with the irreversible MAO-A inhibitor, clorgyline, with the reversible MAO-A inhibitor moclobemide, and with low doses of PCA did not affect either of the responses. Repeated but not single combined treatment with clorgyline plus PCA caused an almost complete blockade of all the four responses. The selective and reversible MAO-A inhibitors (as well as 5-HT releasers) amiflamine, alpha-ethyltryptamine, and alpha-methyltryptamine reduced markedly the ejaculatory response after both single and repeated treatments. The behavioural responses were blocked only after repeated treatment. It is concluded that single and repeated treatments of rats with different MAO inhibitors do not produce a common alteration in 5-HT2 receptor functions. Repeated treatment with 5-MeODMT caused a blockade of 75-95% of the ejaculatory response and 5-HT behavioural responses.(ABSTRACT TRUNCATED AT 250 WORDS) PMID:3091132

Generation of reactive oxygen species (ROS) is a key factor for stimulation of macrophage proliferation by ceramide 1-phosphate

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

Arana, Lide; Gangoiti, Patricia; Ouro, Alberto

2012-02-15

We previously demonstrated that ceramide 1-phosphate (C1P) is mitogenic for fibroblasts and macrophages. However, the mechanisms involved in this action were only partially described. Here, we demonstrate that C1P stimulates reactive oxygen species (ROS) formation in primary bone marrow-derived macrophages, and that ROS are required for the mitogenic effect of C1P. ROS production was dependent upon prior activation of NADPH oxidase by C1P, which was determined by measuring phosphorylation of the p40phox subunit and translocation of p47phox from the cytosol to the plasma membrane. In addition, C1P activated cytosolic calcium-dependent phospholipase A{sub 2} and protein kinase C-{alpha}, and NADPH oxidasemore » activation was blocked by selective inhibitors of these enzymes. These inhibitors, and inhibitors of ROS production, blocked the mitogenic effect of C1P. By using BHNB-C1P (a photolabile caged-C1P analog), we demonstrate that all of these C1P actions are caused by intracellular C1P. It can be concluded that the enzyme responsible for C1P-stimulated ROS generation in bone marrow-derived macrophages is NADPH oxidase, and that this enzyme is downstream of PKC-{alpha} and cPLA{sub 2}-{alpha} in this pathway. -- Highlights: Black-Right-Pointing-Pointer Ceramide 1-phosphate (C1P) stimulates reactive oxygen species (ROS) formation. Black-Right-Pointing-Pointer The enzyme responsible for ROS generation by C1P in macrophages is NADPH oxidase. Black-Right-Pointing-Pointer NADPH oxidase lies downstream of cPLA{sub 2}-{alpha} and PKC-{alpha} in this pathway. Black-Right-Pointing-Pointer ROS generation is essential for the stimulation of macrophage proliferation by C1P.« less

Mitochondrial terminal alternative oxidase and its enhancement by thermal stress in the coral symbiont Symbiodinium

NASA Astrophysics Data System (ADS)

Oakley, Clinton A.; Hopkinson, Brian M.; Schmidt, Gregory W.

2014-06-01

A terminal electron acceptor alternative to mitochondrial cytochrome c oxidase (COX), mitochondrial alternative oxidase (AOX), is ubiquitous in higher plants and represented in nearly every algal taxon but is poorly documented in dinoflagellates. AOX competes for electrons with the conventional COX and has been hypothesized to function as a means of reducing oxidative stress in mitochondria, as well as a potential mechanism for ameliorating thermal and other physiological stressors. Here, the presence of an active AOX in cultured Symbiodinium was assayed by the response of oxygen consumption to the AOX inhibitor salicylhydroxamic acid (SHAM) and the COX inhibitor cyanide (CN). CN-insensitive, SHAM-sensitive oxygen consumption was found to account for a large portion (26 %) of Symbiodinium dark respiration and is consistent with high levels of AOX activity. This experimental evidence of the existence of a previously unreported terminal oxidase was further corroborated by analysis of publicly available Symbiodinium transcriptome data. The potential for enhanced AOX expression to play a compensatory role in mediating thermal stress was supported by inhibitor assays of cultured Symbiodinium at low (18 °C), moderate (26 °C), and high (32 °C) temperature conditions. Maximum capacity of the putative AOX pathway as a proportion of total dark oxygen consumption was found to increase from 26 % at 26 °C to 45 % and 53 % at 18 °C and 32 °C, respectively, when cells were acclimated to the treatment temperatures. Cells assayed at 18 and 32 °C without acclimation exhibited either the same or lower AOX capacity as controls, suggesting that the AOX protein is upregulated under temperature stress. The physiological implications for the presence of AOX in the coral/algal symbiosis and its potential role in response to many forms of biotic and abiotic stress, particularly oxidative stress, are discussed.

Solubilization of Leonardite by an Extracellular Fraction from Coriolus versicolor

PubMed Central

Pyne, John W.; Stewart, Dorothy L.; Fredrickson, James; Wilson, Bary W.

1987-01-01

Coriolus versicolor has previously been shown to degrade leonardite, an oxidized form of lignite. An extracellular fraction containing protein purified from a C. versicolor culture solubilized leonardite in vitro. Expression of the activity did not require the presence of leonardite and appeared during idiophase. During ion-exchange and gel filtration column chromatography, leonardite-biosolubilizing activity eluted with syringaldazine oxidase activity and with protein, as measured by A280 and the biuret protein assay. Syringaldazine is a substrate of the polyphenol oxidase formed by C. versicolor. Comparison of leonardite-biosolubilizing activity with the effects of chelators and surface-active agents on leonardite showed that biosolubilization was not due to either surfactant or chelating ability. Heat treatment of the preparation at 60°C for 30 min significantly reduced both syringaldazine oxidase and leonardite-biosolubilizing activities. Cyanide, azide, and thioglycolate, which are known inhibitors of syringaldazine oxidase activity of C. versicolor, also inhibited leonardite biosolubilization. From these data, we conclude that the purified protein fraction from C. versicolor contains a syringaldazine oxidase activity that participates in leonardite biosolubilization by enzymatic action. PMID:16347501

Effect of mitoguazone on polyamine oxidase activity in rat liver.

PubMed

Ferioli, Maria Elena; Berselli, Debora; Caimi, Samuela

2004-12-01

Mitoguazone is a known inhibitor of polyamine biosynthesis through competitive inhibition of S-adenosylmethionine decarboxylase. A recent renewed interest in mitoguazone as an antineoplastic agent prompted us to investigate the effect of the drug on polyamine catabolism in rat liver, since the organ plays an important role in detoxification mechanisms. Thus, the purpose of this work was to evaluate the effect of in vivo mitoguazone administration on polyamine catabolic enzymes. In particular, our interest was directed to the changes in polyamine oxidase activity, since this enzyme has been recently confirmed to exert important functions that until now were underestimated. Mitoguazone administration induced hepatic polyamine oxidase activity starting at 4 h after administration, and the enzyme returned to basal levels 96 h after treatment. The changes in enzyme activity were accompanied by changes in putrescine concentrations, which increased starting at 4 h until 72 h after treatment. We also evaluated the activity of the newly identified spermine oxidase, which was not significantly changed by mitoguazone treatment. Therefore, we hypothesized that the enzyme involved in mitoguazone response of the liver is the polyamine oxidase, which acts on acetylated polyamines as substrate.

Solubilization of leonardite by an extracellular fraction from Coriolus versicolor

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

Pyne, J.W. Jr.; Stewart, D.L.; Fredrickson, J.

1987-12-01

Coriolus versicolor has previously been shown to degrade leonardite, an oxidized form of lignite. An extracellular fraction containing protein purified from a C. versicolor culture solubilized leonardite in vitro. Expression of the activity did not require the presence of leonardite and appeared during idiophase. During ion-exchange and gel filtration column chromatography, leonardite-biosolubilizing activity eluted with syringaldazine oxidase activity and with protein, as measured by A//sub 280/ and the biuret protein assay. Syringaldazine is a substrate of the polyphenol oxidase formed by C. versicolor. Comparison of leonardite-biosolubilizing activity with the effects of chelators and surface-active agents on leonardite showed that biosolubilizationmore » was not due to either surfactant or chelating ability. Heat treatment of the preparation at 60/sup 0/C for 30 min significantly reduced both syringaldazine oxidase and leonardite-biosolubilizing activities. Cyanide, azide, and thioglycolate, which are know inhibitors of syringaldazine oxidase activity of C. versicolor, also inhibited leonardite biosolubilization. From these data, we conclude that the purified protein fraction from C. versicolor contains a syringaldazine oxidase activity that participates in leonardite biosolubilization by enzymatic action.« less

[Combination of tricyclic antidepressants and MAOI in the depressions].

PubMed

Abdala, E N

1975-03-01

This study was aimed at the assessment of therapeutic and side effects of simultaneous administration of tricyclic antidepressants and MAOI. The sample consisted of 122 patients with depressive syndromes, treated at the "Centro de Psicología Médica San Martín de Tours" (period 1970/1973), with Isocarboxazide and Trimiprimine. All patients received both drugs three times a day. The average daily dose was 20 mg of Isocarboxazide together with 125 mg of Trimiprimine. The average treatment was 70 days long. The study lead to the following conclusions: 1. There were no serious side effects. 2. The scarce side effects registered were not very different from those of the other anti-depressants. 3. The therapeutic doses were lower than those required when each drug is used alone. 4. The speed of action was higher than for each drug separately. 5. The overall percentage of improvement in patients was higher than the percentage obtained for each drug alone. 6. The lack of side effects for a theoretically risky combination of drugs is likely to be attributed to the neuroleptic action of Trimipramine.

Sildenafil citrate and sildenafil nitrate (NCX 911) are potent inhibitors of superoxide formation and gp91phox expression in porcine pulmonary artery endothelial cells

PubMed Central

Muzaffar, Saima; Shukla, Nilima; Srivastava, Amit; Angelini, Gianni D; Jeremy, Jamie Y

2005-01-01

Acute respiratory distress syndrome (ARDS) is associated with increased superoxide (O2•−) formation in the pulmonary vasculature and negation of the bioavailability of nitric oxide (NO). Since NO inhibits NADPH oxidase expression through a cyclic GMP-mediated mechanism, sildenafil, a type V phosphodiesterase inhibitor, may be therapeutically effective in ARDS through an augmentation of NO-mediated inhibition of NADPH oxidase. Therefore, the effect of sildenafil citrate and NO-donating sildenafil (NCX 911) on O2•− formation and gp91phox (active catalytic subunit of NADPH oxidase) expression was investigated in cultured porcine pulmonary artery endothelial cells (PAECs). PAECs were incubated with 10 nM TXA2 analogue, 9,11-dideoxy-9α,11α-methanoepoxy-prostaglandin F2α (U46619) (±sildenafil or NCX 911), for 16 h and O2•− formation measured spectrophometrically and gp91phox using Western blotting. The role of the NO-cGMP axis was studied using morpholinosydnonimine hydrochloride (SIN-1), the diethylamine/NO complex (DETA-NONOate), the guanylyl cyclase inhibitor, 1H-{1,2,4}oxadiazolo{4,3-a}quinoxalin-1-one (ODQ), and the protein kinase G inhibitor, 8-bromoguanosine-3′,5′-cyclic monophosphorothioate, Rp-isomer (Rp-8-Br-cGMPS). NO release was studied using a fluorescence assay and O2•−–NO interactions by measuring nitrites. After a 16-h incubation with 10 nM U46619, both NCX 911 and sildenafil elicited a concentration-dependent inhibition of O2•− formation and gp91phox expression, NCX 911 being more potent (IC50; 0.26 nM) than sildenafil citrate (IC50; 1.85 nM). These inhibitory effects were reversed by 1 μM ODQ and 10 μM Rp-8-Br-cGMPS. NCX 911 stimulated the formation of cGMP in PAECs and generated NO in a cell-free system to a greater degree than sildenafil citrate. The inhibitory effect of sildenafil was augmented by 1 μM SIN-1 and blocked partially by the eNOS inhibitor 10 μM N5-(1-iminoethyl)-ornithine (L-NIO). Acutely, sildenafil and NCX 911 also inhibited O2•− formation, again blocked by 1 μM ODQ. NCX 911 reacted with O2•− generated by xanthine oxidase, an effect that was inhibited by superoxide dismutase (500 U ml−1). Since O2•− formation plays contributory role in ARDS, both sildenafil citrate and NCX 911 may be indicated for treating ARDS through suppression of NADPH oxidase expression and therefore of O2•− formation and preservation of NO bioavailability. PMID:15980872

Construction of a D-amino acid oxidase reactor based on magnetic nanoparticles modified by a reactive polymer and its application in screening enzyme inhibitors.

PubMed

Mu, Xiaoyu; Qiao, Juan; Qi, Li; Liu, Ying; Ma, Huimin

2014-08-13

Developing facile and high-throughput methods for exploring pharmacological inhibitors of D-amino acid oxidase (DAAO) has triggered increasing interest. In this work, DAAO was immobilized on the magnetic nanoparticles, which were modified by a biocompatible reactive polymer, poly(glycidyl methacrylate) (PGMA) via an atom transfer radical polymerization technique. Interestingly, the enzyme immobilization process was greatly promoted with the assistance of a lithium perchlorate catalyst. Meanwhile, a new amino acid ionic liquid (AAIL) was successfully synthesized and employed as the efficient chiral ligand in a chiral ligand exchange capillary electrophoresis (CLE-CE) system for chiral separation of amino acids (AAs) and quantitation of methionine, which was selected as the substrate of DAAO. Then, the apparent Michaelis-Menten constants in the enzyme system were determined with the proposed CLE-CE method. The prepared DAAO-PGMA-Fe3O4 nanoparticles exhibited excellent reusability and good stability. Moreover, the enzyme reactor was successfully applied in screening DAAO inhibitors. These results demonstrated that the enzyme could be efficiently immobilized on the polymer-grafted magnetic nanoparticles and that the obtained enzyme reactor has great potential in screening enzyme inhibitors, further offering new insight into monitoring the relevant diseases.

The properties of B-form monoamine oxidase in mitochondria from monkey platelet.

PubMed

Obata, Toshio; Aomine, Masahiro

The present study was examined the effect of the properties of monkey platelet monoamine oxidase (MAO) based on inhibitor sensitivity. Monkey platelet showed a high MAO activity with beta-phenylethylamine (beta-PEA) as substrate and a very low A-form MAO activity with 5 hydroxytryptamine (5-HT) as substrate. Moreover, monkey platelet MAO was sensitive to the drugs deprenyl as B-form MAO inhibitor and less sensitive to clorgyline and harmaline as A form MAO inhibitor with beta-PEA as the B-form MAO substrate. B-form MAO from monkey platelet was more stable against heat treatment at 55 degrees C than B-form MAO in brain. After digestion with trypsin at 37 degrees C for 4 hrs, it was found that MAO from platelet was inhibited about 70% with beta-PEA as substrate with brain. The tricyclic antidepressant imipramine and nortriptyline inhibited B-form MAO activity more potency than B-form MAO in brain. However, when the noncyclic antidepressant nomifensine was used, monkey platelet B-form MAO activities were less potently inhibited. All these reagents were noncompetitive inhibitors of B form MAO in monkey platelet. The present studies demonstrated that monkey platelet MAO is a single of B-form MAO and sensitive to tricyclic antidepressants.

Attenuation of MPTP-induced dopaminergic neurotoxicity by TV3326, a cholinesterase-monoamine oxidase inhibitor.

PubMed

Sagi, Yotam; Weinstock, Marta; Youdim, Moussa B H

2003-07-01

(R)-[(N-propargyl-(3R) aminoindan-5-yl) ethyl methyl carbamate] (TV3326) is a novel cholinesterase and brain-selective monoamine oxidase (MAO)-A/-B inhibitor. It was developed for the treatment of dementia co-morbid with extra pyramidal disorders (parkinsonism), and depression. On chronic treatment in mice it attenuated striatal dopamine depletion induced by MPTP and prevented the reduction in striatal tyrosine hydroxylase activity, like selective B and non-selective MAO inhibitors. TV3326 preferentially inhibits MAO-B in the striatum and hippocampus, and the degree of MAO-B inhibition correlates with the prevention of MPTP-induced dopamine depletion. Complete inhibition of MAO-B is not necessary for full protection from MPTP neurotoxicity. Unlike that seen after treatment with other MAO-A and -B inhibitors, recovery of striatal and hippocampal MAO-A and -B activities from inhibition by TV3326 did not show first-order kinetics. This has been attributed to the generation of a number of metabolites by TV3326 that cause differential inhibition of these enzymes. Inhibition of brain MAO-A and -B by TV3326 resulted in significant elevations of dopamine, noradrenaline and serotonin in the striatum and hippocampus. This may explain its antidepressant-like activity, resembling that of moclobemide in the forced-swim test in rats.

NADPH oxidase-mediated generation of reactive oxygen species is critically required for survival of undifferentiated human promyelocytic leukemia cell line HL-60.

PubMed

Dong, Jing-Mei; Zhao, Sheng-Guo; Huang, Guo-Yin; Liu, Qing

2004-06-01

Nicotinamide adenine dinucleotide phosphate oxidase (NADPH oxidase) mediated generation of reactive oxygen species (ROS) was originally identified as the powerful host defense machinery against microorganism in phagocytes. But recent reports indicated that some non-phagocytic cells also have the NADPH oxidase activity, and the ROS produced by it may act as cell signal molecule. But as far as today, whether the NADPH oxidase also plays similar role in phagocyte has not been paid much attention. Utilizing the undifferentiated HL-60 promyelocytic leukemia cells as a model, the aim of the present study was to determine whether NADPH oxidase plays a role on ROS generation in undifferentiated HL-60, and the ROS mediated by it was essential for cell's survival. For the first time, we verified that the release of ROS in undifferentiated HL-60 was significantly increased by the stimulation with Calcium ionophore or opsonized zymosan, which are known to trigger respiration burst in phagocytes by NADPH oxidase pathway. Diphenylene iodonium (DPI) or apocynin (APO), two inhibitors of NADPH oxidase, significantly suppressed the increasing of ROS caused by opsonized zymosan. Cell survival assay and fluorescence double dyeing with acridine orange and ethidium bromide showed that DPI and APO, as well as superoxide dismutase (SOD) and catalase (CAT) concentration-dependently decreased the viability of undifferentiated HL-60 cells, whereas exogenous H2O2 can rescue the cells from death obviously. Our results suggested that the ROS, generated by NADPH oxidase play an essential role in the survival of undifferentiated HL-60 cells.

Two polymorphs of safinamide, a selective and reversible inhibitor of monoamine oxidase B.

PubMed

Ravikumar, Krishnan; Sridhar, Balasubramanian

2010-06-01

Two polymorphs of safinamide {systematic name: (2S)-2-[4-(3-fluorobenzyloxy)benzylamino]propionamide}, C(17)H(19)FN(2)O(2), a potent selective and reversible monoamine oxidase B (MAO-B) inhibitor, are described. Both forms are orthorhombic and regarded as conformational polymorphs due to the differences in the orientation of the 3-fluorobenzyloxy and propanamide groups. Both structures pack with layers in the ac plane. In polymorph (I), the layers have discrete wide and narrow regions which are complementary when located next to adjacent layers. In polymorph (II), the layer has long flanges protruding from each side, which interdigitate when packed with the adjacent layers. N-H...O hydrogen bonds are present in both structures, whereas N-H...F hydrogen bonding is seen in polymorph (I), while N-H...N hydrogen bonding is seen in polymorph (II).

Subnanomolar indazole-5-carboxamide inhibitors of monoamine oxidase B (MAO-B) continued: indications of iron binding, experimental evidence for optimised solubility and brain penetration.

PubMed

Tzvetkov, Nikolay T; Antonov, Liudmil

2017-12-01

Pharmacological and physicochemical studies of N-unsubstituted indazole-5-carboxamides (subclass I) and their structurally optimised N1-methylated analogues (subclass II), initially developed as drug and radioligand candidates for the treatment and diagnosis of Parkinson's disease (PD), are presented. The compounds are highly brain permeable, selective, reversible, and competitive monoamine oxidase B (MAO-B) inhibitors with improved water-solubility and subnanomolar potency (pIC 50  >8.8). Using a well-validated, combined X-ray/modelling technology platform, we performed a semi-quantitative analysis of the binding modes of all compounds and investigated the role of the indazole N1 position for their MAO-B inhibitory activity. Moreover, compounds NTZ-1006, 1032, and 1441 were investigated for their ability to bind Fe 2+ and Fe 3+ ions using UV-visible spectroscopy.

Involvement of polyamine oxidase in abscisic acid-induced cytosolic antioxidant defense in leaves of maize.

PubMed

Xue, Beibei; Zhang, Aying; Jiang, Mingyi

2009-03-01

Using pharmacological and biochemical approaches, the role of maize polyamine oxidase (MPAO) in abscisic acid (ABA)-induced antioxidant defense in leaves of maize (Zea mays L.) plants was investigated. Exogenous ABA treatment enhanced the expression of the MPAO gene and the activities of apoplastic MPAO. Pretreatment with two different inhibitors for apoplastic MPAO partly reduced hydrogen peroxide (H2O2) accumulation induced by ABA and blocked the ABA-induced expression of the antioxidant genes superoxide dismutase 4 and cytosolic ascorbate peroxidase and the activities of the cytosolic antioxidant enzymes. Treatment with spermidine, the optimum substrate of MPAO, also induced the expression and the activities of the antioxidant enzymes, and the upregulation of the antioxidant enzymes was prevented by two inhibitors of MPAO and two scavengers of H2O2. These results suggest that MPAO contributes to ABA-induced cytosolic antioxidant defense through H2O2, a Spd catabolic product.

Mitigation of NADPH Oxidase 2 Activity as a Strategy to Inhibit Peroxynitrite Formation*

PubMed Central

Zielonka, Jacek; Zielonka, Monika; VerPlank, Lynn; Cheng, Gang; Hardy, Micael; Ouari, Olivier; Ayhan, Mehmet Menaf; Podsiadły, Radosław; Sikora, Adam; Lambeth, J. David; Kalyanaraman, Balaraman

2016-01-01

Using high throughput screening-compatible assays for superoxide and hydrogen peroxide, we identified potential inhibitors of the NADPH oxidase (Nox2) isoform from a small library of bioactive compounds. By using multiple probes (hydroethidine, hydropropidine, Amplex Red, and coumarin boronate) with well defined redox chemistry that form highly diagnostic marker products upon reaction with superoxide (O2˙̄), hydrogen peroxide (H2O2), and peroxynitrite (ONOO−), the number of false positives was greatly decreased. Selected hits for Nox2 were further screened for their ability to inhibit ONOO− formation in activated macrophages. A new diagnostic marker product for ONOO− is reported. We conclude that the newly developed high throughput screening/reactive oxygen species assays could also be used to identify potential inhibitors of ONOO− formed from Nox2-derived O2˙̄ and nitric oxide synthase-derived nitric oxide. PMID:26839313

NADPH oxidase mediates depressive behavior induced by chronic stress in mice.

PubMed

Seo, Ji-Seon; Park, Jin-Young; Choi, Juli; Kim, Tae-Kyung; Shin, Joo-Hyun; Lee, Ja-Kyeong; Han, Pyung-Lim

2012-07-11

Stress is a potent risk factor for depression, yet the underlying mechanism is not clearly understood. In the present study, we explored the mechanism of development and maintenance of depression in a stress-induced animal model. Mice restrained for 2 h daily for 14 d showed distinct depressive behavior, and the altered behavior persisted for >3 months in the absence of intervention. Acute restraint induced a surge of oxidative stress in the brain, and stress-induced oxidative stress progressively increased with repetition of stress. In vitro, the stress hormone glucocorticoid generated superoxide via upregulation of NADPH oxidase. Consistently, repeated restraints increased the expression of the key subunits of NADPH oxidase, p47phox and p67phox, in the brain. Moreover, stressed brains markedly upregulated the expression of p47phox to weak restress evoked in the poststress period, and this molecular response was reminiscent of amplified ROS surge to restress. Pharmacological inhibition of NADPH oxidase by the NADPH oxidase inhibitor apocynin during the stress or poststress period completely blocked depressive behavior. Consistently, heterozygous p47phox knock-out mice (p47phox(+/-)) or molecular inhibition of p47phox with Lenti shRNA-p47phox in the hippocampus suppressed depressive behavior. These results suggest that repeated stress promotes depressive behavior through the upregulation of NADPH oxidase and the resultant metabolic oxidative stress, and that the inhibition of NADPH oxidase provides beneficial antidepression effects.

Involvement of alternative oxidase in the regulation of sensitivity of Sclerotinia sclerotiorum to the fungicides azoxystrobin and procymidone.

PubMed

Xu, Ting; Wang, Ya-Ting; Liang, Wu-Sheng; Yao, Fei; Li, Yong-Hong; Li, Dian-Rong; Wang, Hao; Wang, Zheng-Yi

2013-06-01

Sclerotinia sclerotiorum is a filamentous fungal pathogen that can infect many economically important crops and vegetables. Alternative oxidase is the terminal oxidase of the alternative respiratory pathway in fungal mitochondria. The function of alternative oxidase was investigated in the regulation of sensitivity of S. sclerotiorum to two commercial fungicides, azoxystrobin and procymidone which have different fungitoxic mechanisms. Two isolates of S. sclerotiorum were sensitive to both fungicides. Application of salicylhydroxamic acid, a specific inhibitor of alternative oxidase, significantly increased the values of effective concentration causing 50% mycelial growth inhibition (EC50) of azoxystrobin to both S. sclerotiorum isolates, whereas notably decreased the EC50 values of procymidone. In mycelial respiration assay azoxystrobin displayed immediate inhibitory effect on cytochrome pathway capacity, but had no immediate effect on alternative pathway capacity. In contrast, procymidone showed no immediate impact on capacities of both cytochrome and alternative pathways in the mycelia. However, alternative oxidase encoding gene (aox) transcript and protein levels, alternative respiration pathway capacity of the mycelia were obviously increased by pre-treatment for 24 h with both azoxystrobin and procymidone. These results indicate that alternative oxidase was involved in the regulation of sensitivity of S. sclerotiorum to the fungicides azoxystrobin and procymidone, and that both fungicides could affect aox gene expression and the alternative respiration pathway capacity development in mycelia of this fungal pathogen.

Inhibition of polyamine and spermine oxidases by polyamine analogues.

PubMed

Bianchi, Marzia; Polticelli, Fabio; Ascenzi, Paolo; Botta, Maurizio; Federico, Rodolfo; Mariottini, Paolo; Cona, Alessandra

2006-03-01

Polyamine oxidase (PAO) and spermine oxidase (SMO) are involved in the catabolism of polyamines--basic regulators of cell growth and proliferation. The discovery of selective inhibitors of PAO and SMO represents an important tool in studying the involvement of these enzymes in polyamine homeostasis and a starting point for the development of novel antineoplastic drugs. Here, a comparative study on murine PAO (mPAO) and SMO (mSMO) inhibition by the polyamine analogues 1,8-diaminooctane, 1,12-diaminododecane, N-prenylagmatine (G3), guazatine and N,N1-bis(2,3-butadienyl)-1,4-butanediamine (MDL72527) is reported. Interestingly, 1,12-Diaminododecane and G3 behave as specific inhibitors of mPAO, values of K(i) for mPAO inhibition being lower than those for mSMO inactivation by several orders of magnitude. The analysis of molecular models of mPAO and mSMO indicates a significant reduction of the hydrophobic pocket located in maize PAO (MPAO) at the wider catalytic tunnel opening. This observation provides a rationale to explain the lower affinity displayed by G3, guazatine and MDL72527 for mPAO and mSMO as compared to MPAO. The different behaviour displayed by 1,12-diaminododecane towards mPAO and mSMO reveals the occurrence of basic differences in the ligand binding mode of the two enzymes, the first enzyme interacting mainly with substrate secondary amino groups and the second one with substrate primary amino groups. Thus, the data reported here provide the basis for the development of novel and selective inhibitors able to discriminate between mammalian SMO and PAO activities.

Characterization of potent and selective iodonium-class inhibitors of NADPH oxidases.

PubMed

Lu, Jiamo; Risbood, Prabhakar; Kane, Charles T; Hossain, Md Tafazzal; Anderson, Larry; Hill, Kimberly; Monks, Anne; Wu, Yongzhong; Antony, Smitha; Juhasz, Agnes; Liu, Han; Jiang, Guojian; Harris, Erik; Roy, Krishnendu; Meitzler, Jennifer L; Konaté, Mariam; Doroshow, James H

2017-11-01

The NADPH oxidases (NOXs) play a recognized role in the development and progression of inflammation-associated disorders, as well as cancer. To date, several NOX inhibitors have been developed, through either high throughput screening or targeted disruption of NOX interaction partners, although only a few have reached clinical trials. To improve the efficacy and bioavailability of the iodonium class NOX inhibitor diphenylene iodonium (DPI), we synthesized 36 analogs of DPI, focusing on improved solubility and functionalization. The inhibitory activity of the analogs was interrogated through cell viability and clonogenic studies with a colon cancer cell line (HT-29) that depends on NOX for its proliferative potential. Lack of altered cellular respiration at relevant iodonium analog concentrations was also demonstrated. Additionally, inhibition of ROS generation was evaluated with a luminescence assay for superoxide, or by Amplex Red® assay for H 2 O 2 production, in cell models expressing specific NOX isoforms. DPI and four analogs (NSCs 740104, 751140, 734428, 737392) strongly inhibited HT-29 cell growth and ROS production with nanomolar potency in a concentration-dependent manner. NSC 737392 and 734428, which both feature nitro functional groups at the meta position, had >10-fold higher activity against ROS production by cells that overexpress dual oxidase 2 (DUOX2) than the other compounds examined (IC 50 ≈200-400nM). Based on these results, we synthesized and tested NSC 780521 with optimized potency against DUOX2. Iodonium analogs with anticancer activity, including the first generation of targeted agents with improved specificity against DUOX2, may provide a novel therapeutic approach to NOX-driven tumors. Published by Elsevier Inc.

Hypoglycemic neuronal death is triggered by glucose reperfusion and activation of neuronal NADPH oxidase

PubMed Central

Suh, Sang Won; Gum, Elizabeth T.; Hamby, Aaron M.; Chan, Pak H.; Swanson, Raymond A.

2007-01-01

Hypoglycemic coma and brain injury are potential complications of insulin therapy. Certain neurons in the hippocampus and cerebral cortex are uniquely vulnerable to hypoglycemic cell death, and oxidative stress is a key event in this cell death process. Here we show that hypoglycemia-induced oxidative stress and neuronal death are attributable primarily to the activation of neuronal NADPH oxidase during glucose reperfusion. Superoxide production and neuronal death were blocked by the NADPH oxidase inhibitor apocynin in both cell culture and in vivo models of insulin-induced hypoglycemia. Superoxide production and neuronal death were also blocked in studies using mice or cultured neurons deficient in the p47phox subunit of NADPH oxidase. Chelation of zinc with calcium disodium EDTA blocked both the assembly of the neuronal NADPH oxidase complex and superoxide production. Inhibition of the hexose monophosphate shunt, which utilizes glucose to regenerate NADPH, also prevented superoxide formation and neuronal death, suggesting a mechanism linking glucose reperfusion to superoxide formation. Moreover, the degree of superoxide production and neuronal death increased with increasing glucose concentrations during the reperfusion period. These results suggest that high blood glucose concentrations following hypoglycemic coma can initiate neuronal death by a mechanism involving extracellular zinc release and activation of neuronal NADPH oxidase. PMID:17404617

Controversies in neurology: why monoamine oxidase B inhibitors could be a good choice for the initial treatment of Parkinson's disease.

PubMed

Löhle, Matthias; Reichmann, Heinz

2011-09-22

Early initiation of pharmacotherapy in Parkinson's disease (PD) is nowadays widely advocated by experts since the delay of treatment has shown to be associated with a significant deterioration of health related quality of life in affected patients. Due to marked advances in PD treatment during the last decades, physicians are nowadays fortunately equipped with a variety of substances that can effectively ameliorate emerging motor symptoms of the disease, among them levodopa, dopamine agonists and monoamine oxidase type B (MAO-B) inhibitors. Despite numerous drug intervention trials in early PD, there is however still ongoing controversy among neurologists which substance to use for the initial treatment of the disease. In multiple studies, MAO-B inhibitors, such as selegiline and rasagiline, have shown to provide mild symptomatic effects, delay the need for levodopa, and to reduce the incidence of motor fluctuations. Although their symptomatic efficacy is inferior compared to dopamine agonists and levodopa, MAO-B inhibitors undoubtedly have fewer side effects and are easy to administer. In contrary to their competitors, MAO-B inhibitors may furthermore offer a chance for disease modification, which so far remains a major unmet need in the management of PD and eventually makes them ideal candidates for the early treatment of the disease. MAO-B inhibitors may constitute a preferable therapeutic option for early PD, mainly due to their favourable safety profile and their putative neuroprotective capabilities. Since the symptomatic effects of MAO-B inhibitors are comparatively mild, dopamine agonists and levodopa should however be considered for initial treatment in those PD patients, in whom robust and immediate symptomatic relief needs to be prioritized.

Demonstration of isoleucine 199 as a structural determinant for the selective inhibition of human monoamine oxidase B by specific reversible inhibitors.

PubMed

Hubálek, Frantisek; Binda, Claudia; Khalil, Ashraf; Li, Min; Mattevi, Andrea; Castagnoli, Neal; Edmondson, Dale E

2005-04-22

Several reversible inhibitors selective for human monoamine oxidase B (MAO B) that do not inhibit MAO A have been described in the literature. The following compounds: 8-(3-chlorostyryl)caffeine, 1,4-diphenyl-2-butene, and trans,trans-farnesol are shown to inhibit competitively human, horse, rat, and mouse MAO B with K(i) values in the low micromolar range but are without effect on either bovine or sheep MAO B or human MAO A. In contrast, the reversible competitive inhibitor isatin binds to all known MAO B and MAO A with similar affinities. Sequence alignments and the crystal structures of human MAO B in complex with 1,4-diphenyl-2-butene or with trans,trans-farnesol provide molecular insights into these specificities. These inhibitors span the substrate and entrance cavities with the side chain of Ile-199 rotated out of its normal conformation suggesting that Ile-199 is gating the substrate cavity. Ile-199 is conserved in all known MAO B sequences except bovine MAO B, which has Phe in this position (the sequence of sheep MAO B is unknown). Phe is conserved in the analogous position in MAO A sequences. The human MAO B I199F mutant protein of MAO B binds to isatin (K(i) = 3 microM) but not to the three inhibitors listed above. The crystal structure of this mutant demonstrates that the side chain of Phe-199 interferes with the binding of those compounds. This suggests that the Ile-199 "gate" is a determinant for the specificity of these MAO B inhibitors and provides a molecular basis for the development of MAO B-specific reversible inhibitors without interference with MAO A function in neurotransmitter metabolism.

Selegiline

MedlinePlus

... of time that levodopa/carbidopa will continue to control symptoms. Selegiline is in a group of medications called monoamine oxidase type B (MAO-B) inhibitors. It works by increasing the amount of dopamine (a natural substance that is needed to control movement) in the brain.

A Plastid Terminal Oxidase Associated with Carotenoid Desaturation during Chromoplast Differentiation1

PubMed Central

Josse, Eve-Marie; Simkin, Andrew J.; Gaffé, Joël; Labouré, Anne-Marie; Kuntz, Marcel; Carol, Pierre

2000-01-01

The Arabidopsis IMMUTANS gene encodes a plastid homolog of the mitochondrial alternative oxidase, which is associated with phytoene desaturation. Upon expression in Escherichia coli, this protein confers a detectable cyanide-resistant electron transport to isolated membranes. In this assay this activity is sensitive to n-propyl-gallate, an inhibitor of the alternative oxidase. This protein appears to be a plastid terminal oxidase (PTOX) that is functionally equivalent to a quinol:oxygen oxidoreductase. This protein was immunodetected in achlorophyllous pepper (Capsicum annuum) chromoplast membranes, and a corresponding cDNA was cloned from pepper and tomato (Lycopersicum esculentum) fruits. Genomic analysis suggests the presence of a single gene in these organisms, the expression of which parallels phytoene desaturase and ζ-carotene desaturase gene expression during fruit ripening. Furthermore, this PTOX gene is impaired in the tomato ghost mutant, which accumulates phytoene in leaves and fruits. These data show that PTOX also participates in carotenoid desaturation in chromoplasts in addition to its role during early chloroplast development. PMID:10938359

Exploration of chlorinated thienyl chalcones: A new class of monoamine oxidase-B inhibitors.

PubMed

Mathew, Bijo; Haridas, Abitha; Uçar, Gülberk; Baysal, Ipek; Adeniyi, Adebayo A; Soliman, Mahmoud E S; Joy, Monu; Mathew, Githa Elizabeth; Lakshmanan, Baskar; Jayaprakash, Venkatesan

2016-10-01

Chalcone has been reported to be a valid scaffold for the design of monoamine oxidase (MAO) inhibitors. This scenario has amplified the momentum for the discovery of heteroaryl based chalcone MAO inhibitors. In the present study, we have synthesized a series of eleven chlorinated thienyl chalcone derivatives substituted with a different functional groups at the para- position on the ring B and investigated for their ability to inhibit human MAO-A and -B. With the exception of compound (2E)-1-(4-chlorocyclopenta-1,3-dien-1-yl)-3-(4-nitrophenyl)prop-2-en-1-one (TC7), which was a selective MAO-A inhibitor, all the other derivatives inhibited hMAO-B potently and selectively with competitive mode of inhibition. The most potent compound (2E)-1-(4-chlorocyclopenta-1,3-dien-1-yl)-3-(4-ethylphenyl)prop-2-en-1-one (TC6) was found to be the best activity and higher selectivity towards hMAO-B with Ki and SI values of 0.31±0.02μM and 16.84, respectively. All the compounds presented in the current study are completely non-toxic with 74-88% viable cells to hepatic cells at 100μM concentration. Molecular docking and molecular dynamics simulation studies were carried out using Autodock-4.2 and Amber 14 to understand the molecular level interaction and energy relation of MAO isoforms with selective MAO-B inhibitor TC6. Copyright © 2016 Elsevier B.V. All rights reserved.

Endosomal NOX2 oxidase exacerbates virus pathogenicity and is a target for antiviral therapy.

PubMed

To, Eunice E; Vlahos, Ross; Luong, Raymond; Halls, Michelle L; Reading, Patrick C; King, Paul T; Chan, Christopher; Drummond, Grant R; Sobey, Christopher G; Broughton, Brad R S; Starkey, Malcolm R; van der Sluis, Renee; Lewin, Sharon R; Bozinovski, Steven; O'Neill, Luke A J; Quach, Tim; Porter, Christopher J H; Brooks, Doug A; O'Leary, John J; Selemidis, Stavros

2017-07-12

The imminent threat of viral epidemics and pandemics dictates a need for therapeutic approaches that target viral pathology irrespective of the infecting strain. Reactive oxygen species are ancient processes that protect plants, fungi and animals against invading pathogens including bacteria. However, in mammals reactive oxygen species production paradoxically promotes virus pathogenicity by mechanisms not yet defined. Here we identify that the primary enzymatic source of reactive oxygen species, NOX2 oxidase, is activated by single stranded RNA and DNA viruses in endocytic compartments resulting in endosomal hydrogen peroxide generation, which suppresses antiviral and humoral signaling networks via modification of a unique, highly conserved cysteine residue (Cys98) on Toll-like receptor-7. Accordingly, targeted inhibition of endosomal reactive oxygen species production abrogates influenza A virus pathogenicity. We conclude that endosomal reactive oxygen species promote fundamental molecular mechanisms of viral pathogenicity, and the specific targeting of this pathogenic process with endosomal-targeted reactive oxygen species inhibitors has implications for the treatment of viral disease.Production of reactive oxygen species is an ancient antimicrobial mechanism, but its role in antiviral defense in mammals is unclear. Here, To et al. show that virus infection activates endosomal NOX2 oxidase and restricts TLR7 signaling, and that an endosomal NOX2 inhibitor decreases viral pathogenicity.

Purification and characterization of polyphenol oxidase from cauliflower (Brassica oleracea L.).

PubMed

Rahman, Andi Nur Faidah; Ohta, Mayumi; Nakatani, Kazuya; Hayashi, Nobuyuki; Fujita, Shuji

2012-04-11

Polyphenol oxidase (PPO) of cauliflower was purified to 282-fold with a recovery rate of 8.1%, using phloroglucinol as a substrate. The enzyme appeared as a single band on sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The estimated molecular weight of the enzyme was 60 and 54 kDa by SDS-PAGE and gel filtration, respectively. The purified enzyme, called phloroglucinol oxidase (PhO), oxidized phloroglucinol (K(m) = 3.3 mM) and phloroglucinolcarboxylic acid. The enzyme also had peroxidase (POD) activity. At the final step, the activity of purified cauliflower POD was 110-fold with a recovery rate of 3.2%. The PhO and POD showed the highest activity at pH 8.0 and 4.0 and were stable in the pH range of 3.0-11.0 and 5.0-8.0 at 5 °C for 20 h, respectively. The optimum temperature was 55 °C for PhO and 20 °C for POD. The most effective inhibitor for PhO was sodium diethyldithiocarbamate at 10 mM (IC(50) = 0.64 and K(i) = 0.15 mM), and the most effective inhibitor for POD was potassium cyanide at 1.0 mM (IC(50) = 0.03 and K(i) = 29 μM).

Effect of Soy Sauce on Serum Uric Acid Levels in Hyperuricemic Rats and Identification of Flazin as a Potent Xanthine Oxidase Inhibitor.

PubMed

Li, Huipin; Zhao, Mouming; Su, Guowan; Lin, Lianzhu; Wang, Yong

2016-06-15

This is the first report on the ability of soy sauce to effectively reduce the serum uric acid levels and xanthine oxidase (XOD) activities of hyperuricemic rats. Soy sauce was partitioned sequentially into ethyl acetate and water fractions. The ethyl acetate fraction with strong XOD inhibition effect was purified further. On the basis of xanthine oxidase inhibitory (XOI) activity-guided purification, nine compounds including 3,4-dihydroxy ethyl cinnamate, diisobutyl terephthalate, harman, daidzein, flazin, catechol, thymine, genistein, and uracil were obtained. It was the first time that 3,4-dihydroxy ethyl cinnamate and diisobutyl terephthalate had been identified from soy sauce. Flazin with hydroxymethyl furan ketone group at C-1 and carboxyl at C-3 exhibited the strongest XOI activity (IC50 = 0.51 ± 0.05 mM). According to fluorescence quenching and molecular docking experiments, flazin could enter into the catalytic center of XOD to interact with Lys1045, Gln1194, and Arg912 mainly by hydrophobic forces and hydrogen bonds. Flazin, catechol, and genistein not only were potent XOD inhibitors but also held certain antioxidant activities. According to ADME (absorption, distribution, metabolism, and excretion) simulation in silico, flazin had good oral bioavailability in vivo.

Design, synthesis, and molecular docking studies of N-(9,10-anthraquinone-2-carbonyl)amino acid derivatives as xanthine oxidase inhibitors.

PubMed

Zhang, Ting-Jian; Li, Song-Ye; Yuan, Wei-Yan; Zhang, Yi; Meng, Fan-Hao

2018-04-01

A series of N-(9,10-anthraquinone-2-carbonyl)amino acid derivatives (1a-j) was designed and synthesized as novel xanthine oxidase inhibitors. Among them, the L/D-phenylalanine derivatives (1d and 1i) and the L/D-tryptophan derivatives (1e and 1j) were effective with micromolar level potency. In particular, the L-phenylalanine derivative 1d (IC 50  = 3.0 μm) and the D-phenylalanine derivative 1i (IC 50  = 2.9 μm) presented the highest potency and were both more potent than the positive control allopurinol (IC 50  = 8.1 μm). Preliminary SAR analysis pointed that an aromatic amino acid fragment, for example, phenylalanine or tryptophan, was essential for the inhibition; the D-amino acid derivative presented equal or greater potency compared to its L-enantiomer; and the 9,10-anthraquinone moiety was welcome for the inhibition. Molecular simulations provided rational binding models for compounds 1d and 1i in the xanthine oxidase active pocket. As a result, compounds 1d and 1i could be promising lead compounds for further investigation. © 2017 John Wiley & Sons A/S.

Congruence between PM H+-ATPase and NADPH oxidase during root growth: a necessary probability.

PubMed

Majumdar, Arkajo; Kar, Rup Kumar

2018-07-01

Plasma membrane (PM) H + -ATPase and NADPH oxidase (NOX) are two key enzymes responsible for cell wall relaxation during elongation growth through apoplastic acidification and production of ˙OH radical via O 2 ˙ - , respectively. Our experiments revealed a putative feed-forward loop between these enzymes in growing roots of Vigna radiata (L.) Wilczek seedlings. Thus, NOX activity was found to be dependent on proton gradient generated across PM by H + -ATPase as evident from pharmacological experiments using carbonyl cyanide m-chlorophenylhydrazone (CCCP; protonophore) and sodium ortho-vanadate (PM H + -ATPase inhibitor). Conversely, H + -ATPase activity retarded in response to different ROS scavengers [CuCl 2 , N, N' -dimethylthiourea (DMTU) and catalase] and NOX inhibitors [ZnCl 2 and diphenyleneiodonium (DPI)], while H 2 O 2 promoted PM H + -ATPase activity at lower concentrations. Repressing effects of Ca +2 antagonists (La +3 and EGTA) on the activity of both the enzymes indicate its possible mediation. Since, unlike animal NOX, the plant versions do not possess proton channel activity, harmonized functioning of PM H + -ATPase and NOX appears to be justified. Plasma membrane NADPH oxidase and H + -ATPase are functionally synchronized and they work cooperatively to maintain the membrane electrical balance while mediating plant cell growth through wall relaxation.

Treatment with polyamine oxidase inhibitor reduces microglial activation and limits vascular injury in ischemic retinopathy

PubMed Central

Patel, C.; Xu, Z.; Shosha, E.; Xing, J.; Lucas, R.; Caldwell, R.W.; Caldwell, R.B.; Narayanan, S.P.

2016-01-01

Retinal vascular injury is a major cause of vision impairment in ischemic retinopathies. Insults such as hyperoxia, oxidative stress and inflammation contribute to this pathology. Previously, we showed that hyperoxia-induced retinal neurodegeneration is associated with increased polyamine oxidation. Here, we are studying the involvement of polyamine oxidases in hyperoxia-induced injury and death of retinal vascular endothelial cells. Newborn C57BL6/J mice were exposed to hyperoxia (70% O2) from postnatal day (P) 7 to 12 and were treated with the polyamine oxidase inhibitor MDL 72527 or vehicle starting at P6. Mice were sacrificed after different durations of hyperoxia and their retinas were analyzed to determine the effects on vascular injury, microglial cell activation, and inflammatory cytokine profiling. The results of this analysis showed that MDL 72527 treatment significantly reduced hyperoxia-induced retinal vascular injury and enhanced vascular sprouting as compared with the vehicle controls. These protective effects were correlated with significant decreases in microglial activation as well as levels of inflammatory cytokines and chemokines. In order to model the effects of polyamine oxidation in causing microglial activation in vitro, studies were performed using rat brain microvascular endothelial cells treated with conditioned-medium from rat retinal microglia stimulated with hydrogen peroxide. Conditioned-medium from activated microglial cultures induced cell stress signals and cell death in microvascular endothelial cells. These studies demonstrate the involvement of polyamine oxidases in hyperoxia-induced retinal vascular injury and retinal inflammation in ischemic retinopathy, through mechanisms involving cross-talk between endothelial cells and resident retinal microglia. PMID:27239699

Novel multifunctional neuroprotective iron chelator-monoamine oxidase inhibitor drugs for neurodegenerative diseases: in vitro studies on antioxidant activity, prevention of lipid peroxide formation and monoamine oxidase inhibition.

PubMed

Zheng, Hailin; Gal, Shunit; Weiner, Lev M; Bar-Am, Orit; Warshawsky, Abraham; Fridkin, Mati; Youdim, Moussa B H

2005-10-01

Iron-dependent oxidative stress, elevated levels of iron and of monoamine oxidase (MAO)-B activity, and depletion of antioxidants in the brain may be major pathogenic factors in Parkinson's disease, Alzheimer's disease and related neurodegenerative diseases. Accordingly, iron chelators, antioxidants and MAO-B inhibitors have shown efficacy in a variety of cellular and animal models of CNS injury. In searching for novel antioxidant iron chelators with potential MAO-B inhibitory activity, a series of new iron chelators has been designed, synthesized and investigated. In this study, the novel chelators were further examined for their activity as antioxidants, MAO-B inhibitors and neuroprotective agents in vitro. Three of the selected chelators (M30, HLA20 and M32) were the most effective in inhibiting iron-dependent lipid peroxidation in rat brain homogenates with IC50 values (12-16 microM), which is comparable with that of desferal, a prototype iron chelator that is not has orally active. Their antioxidant activities were further confirmed using electron paramagnetic resonance spectroscopy. In PC12 cell culture, the three novel chelators at 0.1 microM were able to attenuate cell death induced by serum deprivation and by 6-hydroxydopamine. M30 possessing propargyl, the MAO inhibitory moiety of the anti-Parkinson drug rasagiline, displayed greater neuroprotective potency than that of rasagiline. In addition, in vitro, M30 was a highly potent non-selective MAO-A and MAO-B inhibitor (IC50 < 0.1 microM). However, HLA20 was more selective for MAO-B but had poor MAO inhibition, with an IC50 value of 64.2 microM. The data suggest that M30 and HLA20 might serve as leads in developing drugs with multifunctional activities for the treatment of various neurodegenerative disorders.

Activation of NADPH oxidase mediates increased endoplasmic reticulum stress and left ventricular remodeling after myocardial infarction in rabbits.

PubMed

Li, Bao; Tian, Jing; Sun, Yi; Xu, Tao-Rui; Chi, Rui-Fang; Zhang, Xiao-Li; Hu, Xin-Ling; Zhang, Yue-An; Qin, Fu-Zhong; Zhang, Wei-Fang

2015-05-01

Nicotinamide adenine dinucleotide 3-phosphate (NADPH) oxidase activity and endoplasmic reticulum (ER) stress are increased after myocardial infarction (MI). In this study, we proposed to test whether activation of the NADPH oxidase in the remote non-infarcted myocardium mediates ER stress and left ventricular (LV) remodeling after MI. Rabbits with MI or sham operation were randomly assigned to orally receive an NADPH oxidase inhibitor apocynin or placebo for 30 days. The agents were administered beginning at 1 week after surgery. MI rabbits exhibited decreases in LV fractional shortening, LV ejection fraction and the first derivative of the LV pressure rise, which were abolished by apocynin treatment. NADPH oxidase Nox2 protein and mRNA expressions were increased in the remote non-infarcted myocardium after MI. Immunolabeling further revealed that Nox2 was increased in cardiac myocytes in the remote myocardium. The apocynin treatment prevented increases in the Nox2 expression, NADPH oxidase activity, oxidative stress, myocyte apoptosis and GRP78, CHOP and cleaved caspase 12 protein expression in the remote myocardium. The apocynin treatment also attenuated increases in myocyte diameter and cardiac fibrosis. In cultured H9C2 cardiomyocytes exposed to angiotensin II, an important stimulus for post-MI remodeling, Nox2 knockdown with siRNA significantly inhibited angiotensin II-induced NADPH oxidase activation, reactive oxygen species and GRP78 and CHOP protein expression. We conclude that NADPH oxidase inhibition attenuates increased ER stress in the remote non-infarcted myocardium and LV remodeling late after MI in rabbits. These findings suggest that the activation of NADPH oxidase in the remote non-infarcted myocardium mediates increased ER stress, contributing to myocyte apoptosis and LV remodeling after MI. Copyright © 2015 Elsevier B.V. All rights reserved.

Membrane-bound oxygen reductases of the anaerobic sulfate-reducing Desulfovibrio vulgaris Hildenborough: roles in oxygen defence and electron link with periplasmic hydrogen oxidation.

PubMed

Ramel, F; Amrani, A; Pieulle, L; Lamrabet, O; Voordouw, G; Seddiki, N; Brèthes, D; Company, M; Dolla, A; Brasseur, G

2013-12-01

Cytoplasmic membranes of the strictly anaerobic sulfate-reducing bacterium Desulfovibrio vulgaris Hildenborough contain two terminal oxygen reductases, a bd quinol oxidase and a cc(b/o)o3 cytochrome oxidase (Cox). Viability assays pointed out that single Δbd, Δcox and double ΔbdΔcox deletion mutant strains were more sensitive to oxygen exposure than the WT strain, showing the involvement of these oxygen reductases in the detoxification of oxygen. The Δcox strain was slightly more sensitive than the Δbd strain, pointing to the importance of the cc(b/o)o3 cytochrome oxidase in oxygen protection. Decreased O2 reduction rates were measured in mutant cells and membranes using lactate, NADH, ubiquinol and menadiol as substrates. The affinity for oxygen measured with the bd quinol oxidase (Km, 300 nM) was higher than that of the cc(b/o)o3 cytochrome oxidase (Km, 620 nM). The total membrane activity of the bd quinol oxidase was higher than that of the cytochrome oxidase activity in line with the higher expression of the bd oxidase genes. In addition, analysis of the ΔbdΔcox mutant strain indicated the presence of at least one O2-scavenging membrane-bound system able to reduce O2 with menaquinol as electron donor with an O2 affinity that was two orders of magnitude lower than that of the bd quinol oxidase. The lower O2 reductase activity in mutant cells with hydrogen as electron donor and the use of specific inhibitors indicated an electron transfer link between periplasmic H2 oxidation and membrane-bound oxygen reduction via the menaquinol pool. This linkage is crucial in defence of the strictly anaerobic bacterium Desulfovibrio against oxygen stress.

Myeloperoxidase amplified high glucose-induced endothelial dysfunction in vasculature: Role of NADPH oxidase and hypochlorous acid.

PubMed

Tian, Rong; Ding, Yun; Peng, Yi-Yuan; Lu, Naihao

2017-03-11

Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase-derived reactive oxygen species (ROS) such as superoxide and hydrogen peroxide (H 2 O 2 ), have emerged as important molecules in the pathogenesis of diabetic endothelial dysfunction. Additionally, neutrophils-derived myeloperoxidase (MPO) and MPO-catalyzed hypochlorous acid (HOCl) play important roles in the vascular injury. However, it is unknown whether MPO can use vascular-derived ROS to induce diabetic endothelial dysfunction. In the present study, we demonstrated that NADPH oxidase was the main source of ROS formation in high glucose-cultured human umbilical vein endothelial cells (HUVECs), and played a critical role in high glucose-induced endothelial dysfunction such as cell apoptosis, loss of cell viability and reduction of nitric oxide (NO). However, the addition of MPO could amplify the high glucose-induced endothelial dysfunction which was inhibited by the presence of apocynin (NADPH oxidase inhibitor), catalase (H 2 O 2 scavenger), or methionine (HOCl scavenger), demonstrating the contribution of NADPH oxidase-H 2 O 2 -MPO-HOCl pathway in the MPO/high glucose-induced vascular injury. In high glucose-incubated rat aortas, MPO also exacerbated the NADPH oxidase-induced impairment of endothelium-dependent relaxation. Consistent with these in vitro data, in diabetic rat aortas, both MPO expresion and NADPH oxidase activity were increased while the endothelial function was simultaneously impaired. The results suggested that vascular-bound MPO could amplify high glucose-induced vascular injury in diabetes. MPO-NADPH oxidase-HOCl may represent an important pathogenic pathway in diabetic vascular diseases. Copyright © 2017 Elsevier Inc. All rights reserved.

Rotenone-sensitive mitochondrial potential in Phytomonas serpens: electrophoretic Ca(2+) accumulation.

PubMed

Moysés, Danuza Nogueira; Barrabin, Hector

2004-06-07

Phytomonas sp. are flagellated trypanosomatid plant parasites that cause diseases of economic importance in plantations of coffee, oil palm, cassava and coconuts. Here we investigated Ca(2+) uptake by the vanadate-insensitive compartments using permeabilized Phytomonas serpens promastigotes. This uptake occurs at a rate of 1.13+/-0.23 nmol Ca(2+) mg x protein(-1) min(-1). It is completely abolished by the H(+) ionophore FCCP and by valinomycin and nigericin. It is also inhibited by 2 microM ruthenium red, which, at this low concentration, is known to inhibit the mitochondrial calcium uniport. Furthermore, salicylhydroxamic acid (SHAM) and propylgallate, specific inhibitors of the alternative oxidase in plant and parasite mitochondria, are also effective as inhibitors of the Ca(2+) transport. These compounds abolish the membrane potential that is monitored with safranine O. Rotenone, an inhibitor of NADH-CoQ oxidoreductase, can also dissipate 100% of the membrane potential. It is suggested that the mitochondria of P. serpens can be energized via oxidation of NADH in a pathway involving the NADH-CoQ oxidoreductase and the alternative oxidase to regenerate the ubiquinone. The electrochemical H(+) gradient can be used to promote Ca(2+) uptake by the mitochondria.

In silico identification of novel and selective monoamine oxidase B inhibitors.

PubMed

Yelekçi, Kemal; Büyüktürk, Bora; Kayrak, Nurdan

2013-06-01

Monoamine oxidases (MAO) A and B are flavin adenine dinucleotides containing enzymes bound to the mitochondrial outer membranes of the cells of the brain, liver, intestine, and placenta, as well as platelets. Recently, selective MAO-B inhibitors have received increasing attention due to their neuroprotective properties and the multiple roles they can play in the therapy of neurodegenerative disorders. This study was based on 10 scaffolds that were selected from more than a million lead compounds in the ZINCv12 lead library for their structural and physicochemical properties which inhibit MAO-B. Utilizing ZINC and Accelrys 3.1 fragment-based libraries, which contain about 400 thousand fragments, we generated 200 potential candidates. GOLD, LibDock, and AutoDock 4.02 were used to identify the inhibition constants and their position in the active sites of both MAO isozymes. The dispositions of the candidate molecules within the organism were checked with ADMET PSA 2D (polar surface area) against ADMET AlogP98 (the logarithm of the partition coefficient between n-octanol and water). The MAO-B inhibition activities of the candidates were compared with the properties of rasagiline which is known to be a selective inhibitor of MAO-B.

3-Coumaranone derivatives as inhibitors of monoamine oxidase.

PubMed

Van Dyk, Adriaan S; Petzer, Jacobus P; Petzer, Anél; Legoabe, Lesetja J

2015-01-01

The present study examines the monoamine oxidase (MAO) inhibitory properties of a series of 20 3-coumaranone [benzofuran-3(2H)-one] derivatives. The 3-coumaranone derivatives are structurally related to series of α-tetralone and 1-indanone derivatives, which have recently been shown to potently inhibit MAO, with selectivity for MAO-B (in preference to the MAO-A isoform). 3-Coumaranones are similarly found to selectively inhibit human MAO-B with half-maximal inhibitory concentration (IC50) values of 0.004-1.05 µM. Nine compounds exhibited IC50<0.05 µM for the inhibition of MAO-B. For the inhibition of human MAO-A, IC50 values ranged from 0.586 to >100 µM, with only one compound possessing an IC50<1 µM. For selected 3-coumaranone derivatives, it is established that MAO-A and MAO-B inhibition are reversible since dialysis of enzyme-inhibitor mixtures almost completely restores enzyme activity. On the basis of the selectivity profiles and potent action, it may be concluded that the 3-coumaranone derivatives are suitable leads for the development of selective MAO-B inhibitors as potential treatment for disorders such as Parkinson's disease and Alzheimer's disease.

3-Coumaranone derivatives as inhibitors of monoamine oxidase

PubMed Central

Van Dyk, Adriaan S; Petzer, Jacobus P; Petzer, Anél; Legoabe, Lesetja J

2015-01-01

The present study examines the monoamine oxidase (MAO) inhibitory properties of a series of 20 3-coumaranone [benzofuran-3(2H)-one] derivatives. The 3-coumaranone derivatives are structurally related to series of α-tetralone and 1-indanone derivatives, which have recently been shown to potently inhibit MAO, with selectivity for MAO-B (in preference to the MAO-A isoform). 3-Coumaranones are similarly found to selectively inhibit human MAO-B with half-maximal inhibitory concentration (IC50) values of 0.004–1.05 µM. Nine compounds exhibited IC50<0.05 µM for the inhibition of MAO-B. For the inhibition of human MAO-A, IC50 values ranged from 0.586 to >100 µM, with only one compound possessing an IC50<1 µM. For selected 3-coumaranone derivatives, it is established that MAO-A and MAO-B inhibition are reversible since dialysis of enzyme–inhibitor mixtures almost completely restores enzyme activity. On the basis of the selectivity profiles and potent action, it may be concluded that the 3-coumaranone derivatives are suitable leads for the development of selective MAO-B inhibitors as potential treatment for disorders such as Parkinson’s disease and Alzheimer’s disease. PMID:26491258

Monoamine oxidase-dependent endoplasmic reticulum-mitochondria dysfunction and mast cell degranulation lead to adverse cardiac remodeling in diabetes.

PubMed

Deshwal, Soni; Forkink, Marleen; Hu, Chou-Hui; Buonincontri, Guido; Antonucci, Salvatore; Di Sante, Moises; Murphy, Michael P; Paolocci, Nazareno; Mochly-Rosen, Daria; Krieg, Thomas; Di Lisa, Fabio; Kaludercic, Nina

2018-02-19

Monoamine oxidase (MAO) inhibitors ameliorate contractile function in diabetic animals, but the mechanisms remain unknown. Equally elusive is the interplay between the cardiomyocyte alterations induced by hyperglycemia and the accompanying inflammation. Here we show that exposure of primary cardiomyocytes to high glucose and pro-inflammatory stimuli leads to MAO-dependent increase in reactive oxygen species that causes permeability transition pore opening and mitochondrial dysfunction. These events occur upstream of endoplasmic reticulum (ER) stress and are abolished by the MAO inhibitor pargyline, highlighting the role of these flavoenzymes in the ER/mitochondria cross-talk. In vivo, streptozotocin administration to mice induced oxidative changes and ER stress in the heart, events that were abolished by pargyline. Moreover, MAO inhibition prevented both mast cell degranulation and altered collagen deposition, thereby normalizing diastolic function. Taken together, these results elucidate the mechanisms underlying MAO-induced damage in diabetic cardiomyopathy and provide novel evidence for the role of MAOs in inflammation and inter-organelle communication. MAO inhibitors may be considered as a therapeutic option for diabetic complications as well as for other disorders in which mast cell degranulation is a dominant phenomenon.

[Research on the mechanism and regulation of overtraining-related the function of neutrophils by the inhibitor of NADPH oxidase and glutamine supplementation].

PubMed

Dong, Jing-Mei; Chen, Pei-Jie

2013-07-01

To investigate the method and mechanism for exercise-related immunosuppression via the inhibitor of NADPH oxidase diphenyleneiodonium(DPI) and glutamine supplementation and on the function of neutrophils after overtraining. Fifty male Wistar rats were randomly divided into five groups: a negative control group (C), an overtraining group (E), an overtraining + DPI intervention group (D), an overtraining+ glutamine supplementation group(G) and combined glutamine + DPI intervention group(DG). After 36 - 40 h from the last training, eight rats were randomly selected from each group, and blood was sampled from the orbital vein. ELISAs were used to measure serum cytokine levels and lipid peroxidation in blood plasma. Flow cytometry was used to measure neutrophil respiratory burst and phagocytosis. The activity of NADPH oxidase was assessed by chemiluminescence and the gene expression of gp91(phox) and p47(phox) of the NADPH-oxidase subunit was checked by Western blot. Compared with group C, the plasma concentrations of NO increased in group G, and the NO, cytokine-induced neutrophil chemoattractant (CINC) concentrations in group DG increased significantly. The respiratory burst and phagocytosis function of neutrophils were decreased in group E, but in group DG were increased when compared with those of group E. After overtraining the expression of gp91(phox) and p47(phox) was up regulated in group E. There were no significant changes in other groups except group DG, in which the expression of gp91(phox) was down regulated. Compared with group E, the expression of gp91(phox) and p47(phox) was up regulated in group D, group G and group DG. The activation of NADPH oxidase is responsible for the production of superoxide anions, which may be related to the decrease in neutrophil function after over training and is the mechanism of exercise-related immunosuppression. The DPI treatment combined glutamine supplementation can reverse the decrease neutrophils function after overtraining in vitro.

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

Saad, Fawzy A.; Harvard Medical School, Boston, MA 02115; Torres, Marie

LOX, the principal enzyme involved in crosslinking of collagen, was the first of several lysyl oxidase isotypes to be characterized. Its active form was believed to be exclusively extracellular. Active LOX was later reported to be present in cell nuclei; its function there is unknown. LOX expression opposes the effect of mutationally activated Ras, which is present in about 30% of human cancers. The mechanism of LOX in countering the action of Ras is also unknown. In the present work, assessment of nuclear protein for possible effects of lysyl oxidase activity led to the discovery that proliferating cells dramatically increasemore » their nuclear protein content when exposed to BAPN ({beta}-aminopropionitrile), a highly specific lysyl oxidase inhibitor that reportedly blocks LOX inhibition of Ras-induced oocyte maturation. In three cell types (PC12 cells, A7r5 smooth muscle cells, and NIH 3T3 fibroblasts), BAPN caused a 1.8-, 1.7-, and 2.1-fold increase in total nuclear protein per cell, respectively, affecting all major components in both nuclear matrix and chromatin fractions. Since nuclear size is correlated with proliferative status, enzyme activity restricting nuclear growth may be involved in the lysyl oxidase tumor suppressive effect. Evidence is also presented for the presence of apparent lysyl oxidase isotype(s) containing a highly conserved LOX active site sequence in the nuclei of PC12 cells, which do not manufacture extracellular lysyl oxidase substrates. Results reported here support the hypothesis that nuclear lysyl oxidase regulates nuclear growth, and thereby modulates cell proliferation.« less

Macrophage differentiation increases expression of the ascorbate transporter (SVCT2)

PubMed Central

Qiao, Huan; May, James M.

2013-01-01

To determine whether macrophage differentiation involves increased uptake of vitamin C, or ascorbic acid, we assessed the expression and function of its transporter SVCT2 during phorbol ester-induced differentiation of human-derived THP-1 monocytes. Induction of THP-1 monocyte differentiation by phorbol 12-myristate 13-acetate (PMA) markedly increased SVCT2 mRNA, protein, and function. When ascorbate was present during PMA-induced differentiation, the increase in SVCT2 protein expression was inhibited, but differentiation was enhanced. PMA-induced SVCT2 protein expression was blocked by inhibitors of protein kinase C (PKC), with most of the affect due to the PKCβI and βII isoforms. Activation of MEK/ERK was sustained up to 48 h after PMA treatment, and the inhibitors completely blocked PMA-stimulated SVCT2 protein expression, indicating an exclusive role for the classical MAP kinase pathway. However, inhibitors of NF-κB activation, NADPH oxidase inhibitors, and several antioxidants also partially prevented SVCT2 induction, suggesting diverse distal routes for control of SVCT2 transcription. Both known promoters for the SVCT2 were involved in these effects. In conclusion, PMA-induced monocyte-macrophage differentiation is enhanced by ascorbate and associated with increased expression and function of the SVCT2 protein through a pathway involving sustained activation of PKCβI/II, MAP kinase, NADPH oxidase, and NF-κB. PMID:19232538

Preferential inhibition of the plasma membrane NADH oxidase (NOX) activity by diphenyleneiodonium chloride with NADPH as donor

NASA Technical Reports Server (NTRS)

Morre, D. James

2002-01-01

The cell-surface NADH oxidase (NOX) protein of plant and animal cells will utilize both NADH and NADPH as reduced electron donors for activity. The two activities are distinguished by a differential inhibition by the redox inhibitor diphenyleneiodonium chloride (DPI). Using both plasma membranes and cells, activity with NADPH as donor was markedly inhibited by DPI at submicromolar concentrations, whereas with NADH as donor, DPI was much less effective or had no effect on the activity. The possibility of the inhibition being the result of two different enzymes was eliminated by the use of a recombinant NOX protein. The findings support the concept that NOX proteins serve as terminal oxidases for plasma membrane electron transport involving cytosolic reduced pyridine nucleotides as the natural electron donors and with molecular oxygen as the electron acceptor.

AUTONOMIC AND BEHAVIORAL THERMOREGULATION IN THE GOLDEN HAMSTER DURING SUBCHRONIC ADMINISTRATION OF CLORGYLINE

EPA Science Inventory

Chronic administration of clorgyline, a type-A monoamine oxidase inhibitor, leads to a decrease in peritoneal (i.e., core) temperature of golden hamsters. o better understand the mechanisms of clorgyline's thermoregulatory effects, autonomic and behavioral thermoregulatory effect...

Effect of sildenafil citrate and a nitric oxide donating sildenafil derivative, NCX 911, on cavernosal relaxation and superoxide formation in hypercholesterolaemic rabbits.

PubMed

Shukla, Nilima; Jones, Robert; Persad, Raj; Angelini, Gianni D; Jeremy, Jamie Y

2005-07-11

Hypercholesterolaemia promotes erectile dysfunction through increased superoxide formation and negation of nitric oxide (NO) bioactivity in cavernosal tissue. The source of superoxide has not been clearly defined, however. Sildenafil (Viagra), the standard therapy for erectile dysfunction, may also be rendered more effective by the presence of an NO donor. One drug that intrinsically fulfils this criterion is sildenafil nitrate (NCX 911), an NO donating derivative of sildenafil. The objective of this study, therefore, was to determine the source of superoxide and its effect on erectile function in corpus cavernosum from hypercholesterolaemic rabbits and to determine whether NCX 911 confers an improvement over sildenafil citrate in this model. Hypercholesterolaemia elicited an increase in superoxide formation by rabbit cavernosal tissue and a reduction of carbachol-stimulated relaxation both of which were reversed by diphenylene iodonium chloride and apocynin (NADPH oxidase inhibitors). In response to sodium nitroprusside, hypercholesterolaemia also caused an attenuation of cavernosal relaxation which was not reversed with NADPH oxidase inhibitors. Both sildenafil citrate and NCX 911 significantly reversed impaired carbachol-stimulated relaxation and inhibited superoxide formation by cavernosal tissue from hypercholesterolaemic rabbits, NCX 911 being more potent. NCX 911 also augmented cavernosal cGMP levels, an effect blocked by the guanylyl cyclase inhibitor, 1H-{1,2,4}oxadiazolo {4,3-a}quinoxalin-1-one (ODQ). These data demonstrate that hypercholesterolaemia promotes erectile dysfunction through an augmentation of superoxide derived from NADPH oxidase in cavernosal tissue. It also indicates that NO donating sildenafil may be therapeutically more beneficial than conventional sildenafil in treating erectile dysfunction with an oxidative stress-related aetiology.

Transtelephonic home blood pressure to assess the monoamine oxidase-B inhibitor rasagiline in Parkinson disease.

PubMed

White, William B; Salzman, Phyllis; Schwid, Steven R

2008-09-01

Monoamine oxidase inhibitors are associated with dietary tyramine interactions that can induce hypertensive crises. Rasagiline mesylate is a novel irreversible selective monoamine oxidase type B inhibitor for Parkinson disease that may have a low risk of interaction with dietary tyramine because of its selectivity. To study interactions of rasagiline with diets unrestricted in tyramine-containing foods, we incorporated transtelephonic, self-monitoring of the blood pressure (BP) into a randomized, placebo-controlled trial of rasagiline 0.5 and 1.0 mg daily in 414 levodopa-treated Parkinson patients with motor fluctuations. The proportion of patients with a systolic BP increase of >30 mm Hg was the primary BP end point. In 13 968 self-measured readings at baseline, the proportion of systolic BP values that increased by >30 mm Hg after a meal ranged from 9.5% to 12.9% in the 3 treatment groups. In 25 733 BPs obtained postrandomization, the proportion of values with a >30-mm Hg systolic postprandial increase was 15% in the placebo group, 15% in the rasagiline 0.5-mg group, and 11% in the rasagiline 1-mg group after 3 weeks of double-blind therapy and 13%, 14%, and 12%, respectively, after 26 weeks of treatment (P value was not significant for all of the comparisons among treatment groups). A postprandial increase in systolic BP to >180 mm Hg at any time after randomization was seen in 3.3%, 2.6%, and 2.9% of the placebo, 0.5-mg, and 1.0-mg rasagiline groups, respectively. These data demonstrate that rasagiline did not induce postprandial hypertension in patients with Parkinson disease who were on an unrestricted diet.

5-hydroxytryptamine actions in adipocytes: involvement of monoamine oxidase-dependent oxidation and subsequent PPARγ activation.

PubMed

Grès, Sandra; Gomez-Zorita, Saioa; Gomez-Ruiz, Ana; Carpéné, Christian

2013-06-01

Serotonin (5-HT) is a brain neurotransmitter instrumental for the antidepressant action of selective inhibitors of serotonin reuptake (SSRIs) while it also plays important roles in peripheral organs. Recently, the 5-HT oxidation products, 5-hydroxyindoleacetate and 5-methoxy-indoleacetate, have been shown to bind to peroxisome proliferator-activated receptor γ (PPARγ) and to enhance lipid accumulation in preadipocytes. Since we already reported that adipocytes exhibit elevated monoamine oxidase (MAO) and primary amine oxidase activities, we verified how adipocytes readily oxidize 5-HT, with the objective to determine whether such oxidation promotes PPARγ activation and lipid storage. To this aim, serotonin was tested on cultured 3T3 F442A preadipocytes and on human adipocytes. Results showed that 5-HT was oxidized by MAO in both models. Daily treatment of 3T3 F442A preadipocytes for 8 days with 100-500 μM 5-HT promoted triglyceride accumulation and emergence of adipogenesis markers. At 250 μM, 5-HT alone reproduced half of 50 nM insulin-induced adipogenesis, and exhibited an additive differentiating effect when combined with insulin. Moreover, the 5-HT-induced expression of PPARγ-responsive genes (PEPCK, aP2/FABP4) was blocked by GW 9662, a PPARγ-inhibitor, or by pargyline, a MAO-inhibitor. In human fat cells, 6-h exposure to 100 μM 5-HT increased PEPCK expression as did the PPARγ-agonist rosiglitazone. Since hydrogen peroxide, another amine oxidation product, did not reproduce such enhancement, we propose that serotonin can promote PPARγ activation in fat cells, via the indoleacetate produced during MAO-dependent oxidation. Such pathway could be involved in the adverse effects of several antidepressant SSRIs on body weight gain.

The “gating” residues Ile199 and Tyr326 in human monoamine oxidase B function in substrate and inhibitor recognition

PubMed Central

Milczek, Erika M.; Binda, Claudia; Rovida, Stefano; Mattevi, Andrea; Edmondson, Dale E.

2011-01-01

Summary The major structural difference between human monoamine oxidases A (MAO A) and B (MAO B) is that MAO A has a monopartite substrate cavity of ~550 Å3 volume and MAO B contains a dipartite cavity structure with volumes of ~290 Å3 (entrance cavity) and ~400 Å3 (substrate cavity). Ile199 and Tyr326 side chains separate these two cavities in MAO B. To probe the function of these gating residues, Ile199Ala and Ile199Ala Tyr326Ala mutant forms of MAO B were investigated. Structural data on the Ile199Ala MAO B mutant show no alterations in active site geometries compared to WT enzyme while the Ile199Ala-Tyr326Ala MAO B mutant exhibits alterations in residues 100–103 which are part of the loop gating the entrance to the active site. Both mutant enzymes exhibit catalytic properties with increased amine KM but unaltered kcat values. The altered KM values on mutation are attributed to the influence of the cavity structure in the binding and subsequent deprotonation of the amine substrate. Both mutant enzymes exhibit weaker binding affinities relative to WT enzyme for small reversible inhibitors. Ile199Ala MAO B exhibits an increase in binding affinity for reversible MAO B specific inhibitors which bridge both cavities. The Ile199Ala-Tyr326Ala double mutant exhibits inhibitor binding properties more similar to those of MAO A than to MAO B. These results demonstrate the bipartite cavity structure in MAO B plays an important role in substrate and inhibitor recognition to distinguish its specificities from those of MAO A and provides insights into specific reversible inhibitor design for these membrane-bound enzymes. PMID:21978362

The inhibition of monoamine oxidase by phenformin and pentamidine.

PubMed

Barkhuizen, M; Petzer, A; Petzer, J P

2014-09-01

A computational study has suggested that phenformin, an oral hypoglycaemic drug, may bind to the active sites of the monoamine oxidase (MAO) A and B enzymes. The present study therefore investigates the MAO inhibitory properties of phenformin. Pentamidine, a structurally related diamidine compound, has previously been reported to be a MAO inhibitor and was included in this study as a reference compound. Using recombinant human MAO-A and MAO-B, this study finds that phenformin acts as a moderately potent MAO-A selective inhibitor with an IC50 value of 41 µM. Pentamidine, on the other hand, potently inhibits both MAO-A and MAO-B with IC50 values of 0.61 μM and 0.22 μM, respectively. An examination of the recoveries of the enzymatic activities after dilution and dialysis of the enzyme-inhibitor complexes shows that both compounds interact reversibly with the MAO enzymes. A kinetic analysis suggests that pentamidine acts as a competitive inhibitor with estimated Ki values of 0.41 μM and 0.22 μM for the inhibition of MAO-A and MAO-B, respectively. Phenformin also exhibited a competitive mode of MAO-A inhibition with an estimated Ki value of 65 µM. This study concludes that biguanide and amidine functional groups are most likely important structural features for the inhibition of the MAOs by phenformin and pentamidine, and compounds containing these and closely related functional groups should be considered as potential MAO inhibitors. Furthermore, the biguanide and amidine functional groups may act as useful moieties in the future design of MAO inhibitors. © Georg Thieme Verlag KG Stuttgart · New York.

Ethanol increases matrix metalloproteinase-12 expression via NADPH oxidase-dependent ROS production in macrophages

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

Kim, Mi Jin; Nepal, Saroj; Lee, Eung-Seok

2013-11-15

Matrix metalloproteinase-12 (MMP-12), an enzyme responsible for degradation of extracellular matrix, plays an important role in the progression of various diseases, including inflammation and fibrosis. Although most of those are pathogenic conditions induced by ethanol ingestion, the effect of ethanol on MMP-12 has not been explored. In the present study, we investigated the effect of ethanol on MMP-12 expression and its potential mechanisms in macrophages. Here, we demonstrated that ethanol treatment increased MMP-12 expression in primary murine peritoneal macrophages and RAW 264.7 macrophages at both mRNA and protein levels. Ethanol treatment also significantly increased the activity of nicotinamide adenine dinucleotidemore » (NADPH) oxidase and the expression of NADPH oxidase-2 (Nox2). Pretreatment with an anti-oxidant (N-acetyl cysteine) or a selective inhibitor of NADPH oxidase (diphenyleneiodonium chloride (DPI)) prevented ethanol-induced MMP-12 expression. Furthermore, knockdown of Nox2 by small interfering RNA (siRNA) prevented ethanol-induced ROS production and MMP-12 expression in RAW 264.7 macrophages, indicating a critical role for Nox2 in ethanol-induced intracellular ROS production and MMP-12 expression in macrophages. We also showed that ethanol-induced Nox2 expression was suppressed by transient transfection with dominant negative IκB-α plasmid or pretreatment with Bay 11-7082, a selective inhibitor of NF-κB, in RAW 264.7 macrophages. In addition, ethanol-induced Nox2 expression was also attenuated by treatment with a selective inhibitor of p38 MAPK, suggesting involvement of p38 MAPK/NF-κB pathway in ethanol-induced Nox2 expression. Taken together, these results demonstrate that ethanol treatment elicited increase in MMP-12 expression via increase in ROS production derived from Nox2 in macrophages. - Highlights: • Ethanol increases ROS production through up-regulation of Nox2 in macrophages. • Enhanced oxidative stress contributes to ethanol-induced MMP-12 expression. • p38 MAPK/NF-κB signaling pathway modulates ethanol-induced Nox2 expression.« less

Serine 1179 phosphorylation of endothelial nitric oxide synthase caused by 2,4,6-trinitrotoluene through PI3K/Akt signaling in endothelial cells

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

Sun Yang; Sumi, Daigo; Kumagai, Yoshito

2006-07-01

Although 2,4,6-trinitrotoluene (TNT) has been found to uncouple nitric oxide synthase (NOS), thereby leading to reactive oxygen species (ROS), cellular response against TNT still remains unclear. Exposure of bovine aortic endothelial cells (BAECs) to TNT (100 {mu}M) resulted in serine 1179 phosphorylation of endothelial NOS (eNOS). With specific inhibitors (wortmannin and LY294002), we found that PI3K/Akt signaling participated in the eNOS phosphorylation caused by TNT, whereas the ERK pathway did not. ROS were generated following exposure of BAECs to TNT. However, TNT-mediated phosphorylation of either eNOS or Akt was drastically blocked by NAC and PEG-CAT. Interestingly, pretreatment with apocynin, amore » specific inhibitor for NADPH oxidase, diminished the phosphorylation of eNOS and Akt. These results suggest that TNT affects NADPH oxidase, thereby generating hydrogen peroxide, which is capable of activating PI3K/Akt signaling associated with eNOS Ser 1179 phosphorylation.« less

Inhibition of the. beta. -carboxylation pathway of CO/sub 2/ fixation by bisulfite compounds. [Leaves of Sedum praealtum and Atriplex spongiosa were used

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

Osmond, C.B.; Avadhani, P.N.

1970-01-01

Bisulfite compounds are well known as inhibitors of glycolate oxidase in green tissues of higher plants. In an effort to understand the relation between low glycolate oxidase activity and high P-enolpyruvate carboxylase activity in plants with the C/sub 4/ dicarboxylic acid pathway of photosynthesis, the authors have treated leaves of related species of Atriplex with these compounds. In this photosynthetic process, as well as during dark CO/sub 2/ fixation leading to acidification of Sedum leaves, they have found bisulfite compounds to be effective inhibitors of the P-enolpyruvate carboxylation system. This report provides evidence in vivo for this inhibition and describesmore » the inhibition in vitro of P-enolpyruvate carboxylation system. This report provides evidence in vivo for this inhibition and describes the inhibition in vitro of P-enolpyruvate carboxylase and NADH malate dehydrogenase. 16 references, 4 figures, 1 table.« less

Structure-based design and biological evaluation of novel 2-(indol-2-yl) thiazole derivatives as xanthine oxidase inhibitors.

PubMed

Song, Jeong Uk; Jang, Jae Wan; Kim, Tae Hun; Park, Heuisul; Park, Wan Su; Jung, Sang-Hun; Kim, Geun Tae

2016-02-01

Inhibition of xanthine oxidase (XO) has obviously been a central concept for controlling hyperuricemia, which causes serious and painful inflammatory arthritis disease such as gout. We discovered a series of novel 2-(indol-2-yl)thiazole derivatives as XO inhibitors at the level of nanomolar activity. Structure-guided design using molecular modeling program (Accelrys Software program) provided an excellent basis for optimization of 2-(indol-2-yl)thiazole compounds. Structure-activity relationship indicated that hydrophobic alkoxy group (isopropoxy, cyclopentoxy) at 5-position and hydrogen binding acceptor (NO2, CN) at 7-position of indole ring appear as critical functional groups. Among the compounds, 2-(7-nitro-5-isopropoxy-indol-2-yl)-4-methylthiazole-5-carboxylic acid (9m) exhibits the most potent XO inhibitory activity (IC50 value: 5.1 nM) and the excellent uric acid lowering activity in potassium oxonate induced hyperuricemic rat model. Copyright © 2016. Published by Elsevier Ltd.

Postharvest Exogenous Application of Abscisic Acid Reduces Internal Browning in Pineapple.

PubMed

Zhang, Qin; Liu, Yulong; He, Congcong; Zhu, Shijiang

2015-06-10

Internal browning (IB) is a postharvest physiological disorder causing economic losses in pineapple, but there is no effective control measure. In this study, postharvest application of 380 μM abscisic acid (ABA) reduced IB incidence by 23.4-86.3% and maintained quality in pineapple fruit. ABA reduced phenolic contents and polyphenol oxidase and phenylalanine ammonia lyase activities; increased catalase and peroxidase activities; and decreased O2(·-), H2O2, and malondialdehyde levels. This suggests ABA could control IB through inhibiting phenolics biosynthesis and oxidation and enhancing antioxidant capability. Furthermore, the efficacy of IB control by ABA was not obviously affected by tungstate, ABA biosynthesis inhibitor, nor by diphenylene iodonium, NADPH oxidase inhibitor, nor by lanthanum chloride, calcium channel blocker, suggesting that ABA is sufficient for controlling IB. This process might not involve H2O2 generation, but could involve the Ca(2+) channels activation. These results provide potential for developing effective measures for controlling IB in pineapple.

Evidence for a Cyanine Link between Propargylamine Drugs and Monoamine Oxidase Clarifies the Inactivation Mechanism

NASA Astrophysics Data System (ADS)

Albreht, Alen; Vovk, Irena; Mavri, Janez; Marco-Contelles, Jose; Ramsay, Rona R.

2018-05-01

Successful propargylamine drugs such as deprenyl inactivate monoamine oxidase (MAO), a target in multi-faceted approaches to prevent neurodegeneration in the aging population, but the chemical structure and mechanism of the irreversible inhibition are still debated. We characterized the covalent cyanine structure linking the multi-target propargylamine inhibitor ASS234 and the flavin adenine dinucleotide in MAO-A using a combination of ultra-high performance liquid chromatography, spectroscopy, mass spectrometry, and computational methods. The partial double bond character of the cyanine chain gives rise to 4 interconverting geometric isomers of the adduct which were chromatographically separated at low temperatures. The configuration of the cyanine linker governs adduct stability with segments of much higher flexibility and rigidity than previously hypothesized. The findings indicate the importance of intramolecular electrostatic interactions in the MAO binding site and provide key information relevant to incorporation of the propargyl moiety into novel multi-target drugs. Based on the structure, we propose a mechanism of MAO inactivation applicable to all propargylamine inhibitors.

[Effect of inducers and inhibitors of mixed function oxidases on body resistance to endotoxins of gram-negative bacteria].

PubMed

Liniuchev, M N; Zubik, T M; Kovelenov, A Iu; Bulyko, V I; Sergeev, V V

1989-06-01

Experimental typhoid intoxication in white mice leads to the inhibition of microsomal oxidation in the liver, which is manifested by the prolongation of hexenal-induced sleep and a decrease in the toxic action of parathion. Phenobarbital, capable of inducing oxidases with mixed function (OMF), enhances the process of the detoxification of endotoxin injected into the animals, which is manifested by the increase of its LD50. Soluble levomycetin succinate, widely used for the treatment of typhoid-paratyphoid infections, is a powerful inhibitor of OMF (as shown by the hexenal test). Benzonal, the analog of phenobarbital, removes the inhibitory effect of the antibiotic. Experimental studies carried out in the course of this investigation make it possible to substantiate the clinical trial of these preparations (OMF inducers) used in the complex therapy of typhoid-paratyphoid infections for the stimulation of natural detoxification mechanisms of the body. Benzonal is the preparation of choice for use in clinical practice.

Identification of novel monoamine oxidase B inhibitors by structure-based virtual screening.

PubMed

Geldenhuys, Werner J; Darvesh, Altaf S; Funk, Max O; Van der Schyf, Cornelis J; Carroll, Richard T

2010-09-01

Parkinson's disease is a severe debilitating neurodegenerative disorder. Recently, it was shown that the peroxisome proliferating-activator receptor-gamma agonist pioglitazone protected mice from 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine neurotoxicity due to its ability to inhibit monoamine oxidase B (MAO-B). Docking studies were initiated to investigate pioglitazone's interactions within the substrate cavity of MAO-B. Modeling studies indicated that the thiazolidinedione (TZD) moiety was a likely candidate for its specificity to MAO-B. To explore this potential novel MAO-B scaffold, we performed a structure-based virtual screen to identify additional MAO-B inhibitors. Our search identified eight novel compounds containing the TZD-moiety that allowed for a limited study to identify structural requirements for binding to MAO-B. Inhibition assays identified two TZDs (A6355 and L136662) which were found to inhibit recombinant human MAO-B with IC(50) values of 82 and 195 nM, respectively. Copyright 2010 Elsevier Ltd. All rights reserved.

Sleep apneas are increased in mice lacking monoamine oxidase A.

PubMed

Real, Caroline; Popa, Daniela; Seif, Isabelle; Callebert, Jacques; Launay, Jean-Marie; Adrien, Joëlle; Escourrou, Pierre

2007-10-01

Alterations in the serotonin (5-HT) system have been suggested as a mechanism of sleep apnea in humans and rodents. The objective is to evaluate the contribution of 5-HT to this disorder. We studied sleep and breathing (whole-body plethysmography) in mutant mice that lack monoamine oxidase A (MAOA) and have increased concentrations of monoamines, including 5-HT. Compared to wild-type mice, the mutants showed similar amounts of slow wave sleep (SWS) and rapid eye movement sleep (REMS), but exhibited a 3-fold increase in SWS and REMS apnea indices. Acute administration of the MAOA inhibitor clorgyline decreased REMS amounts and increased the apnea index in wild-type but not mutant mice. Parachlorophenylalanine, a 5-HT synthesis inhibitor, reduced whole brain concentrations of 5-HT in both strains, and induced a decrease in apnea index in mutant but not wild-type mice. Our results show that MAOA deficiency is associated with increased sleep apnea in mice and suggest that an acute or chronic excess of 5-HT contributes to this phenotype.

Phosphorescent inner filter effect-based sensing of xanthine oxidase and its inhibitors with Mn-doped ZnS quantum dots.

PubMed

Tang, Dandan; Zhang, Jinyi; Zhou, Rongxin; Xie, Ya-Ni; Hou, Xiandeng; Xu, Kailai; Wu, Peng

2018-05-10

Overexpression and crystallization of uric acid have been recognized as the course of hyperuricemia and gout, which is produced via xanthine oxidase (XOD)-catalyzed oxidation of xanthine. Therefore, the medicinal therapy of hyperuricemia and gout is majorly based on the inhibition of the XOD enzymatic pathway. The spectroscopic nature of xanthine and uric acid, namely both absorption (near the ultraviolet region) and emission (non-fluorescent) characteristics, hinders optical assay development for XOD analysis. Therefore, the state-of-the-art analysis of XOD and the screening of XOD inhibitors are majorly based on chromatography. Here, we found the near ultraviolet absorption of uric acid overlapped well with the absorption of a large bandgap semiconductor quantum dots, ZnS. On the other hand, the intrinsic weak fluorescence of ZnS QDs can be substantially improved via transition metal ion doping. Therefore, herein, we developed an inner filter effect-based assay for XOD analysis and inhibitor screening with Mn-doped ZnS QDs. The phosphorescence of Mn-doped ZnS QDs could be quenched by uric acid generated from xanthine catabolism by XOD, leading to the phosphorescence turn-off detection of XOD with a limit of detection (3σ) of 0.02 U L-1. Furthermore, the existence of XOD inhibitors could inhibit the XOD enzymatic reaction, resulting in weakened phosphorescence quenching. Therefore, the proposed assay could also be explored for the facile screening analysis of XOD inhibitors, which is important for the potential medicinal therapy of hyperuricemia and gout.

Synthesis and in vitro Evaluation of 2-heteroarylidene-1-tetralone Derivatives as Monoamine Oxidase Inhibitors.

PubMed

Amakali, Klaudia T; Legoabe, Lesetja J; Petzer, Anél; Petzer, Jacobus P

2018-05-14

The present study investigates the human monoamine oxidase (MAO) inhibition properties of a series of twelve 2-heteroarylidene-1-tetralone derivatives. Also included are related cyclohexylmethylidene, cyclopentylmethylidene and benzylidene substituted 1-tetralones. These compounds are related to the 2-benzylidene-1-indanone class of compounds which has previously been shown to inhibit the MAOs, with specificity for the MAO-B isoform. The target compounds were synthesised by the Claisen-Schmidt condensation between 7-methoxy-1-tetralone or 1-tetralone, and various aldehydes, under acid (hydrochloric acid) or base (potassium hydroxide) catalysis. The results of the MAO inhibition studies showed that the 2-heteroarylidene-1-tetralone and related derivatives are in most instances more selective inhibitors of the MAO-B isoform compared to MAO-A. (2E)-2-Benzylidene-7-methoxy-3,4-dihydronaphthalen-1(2 H)-one (IC 50 =0.707 μM) was found to be the most potent MAO-B inhibitor, while the most potent MAO-A inhibitor was (2E)-2-[(2-chloropyridin-3-yl)methylidene]-7-methoxy-3,4-dihydronaphthalen-1(2 H)-one (IC 50 =1.37 μM). The effect of the heteroaromatic substituent on MAO-B inhibition activity, in decreasing order was found to be: cyclohexyl, phenyl>thiophene>pyridine, furane, pyrrole, cyclopentyl. This study concludes that, although some 2-heteroarylidene-1-tetralone derivatives are good potency MAO inhibitors, in general their inhibition potencies, particularly for MAO-B, are lower than structurally related chalcones and 1-indanone derivatives that were previously studied. © Georg Thieme Verlag KG Stuttgart · New York.

Genomic sequencing of uric acid metabolizing and clearing genes in relationship to xanthine oxidase inhibitor dose.

PubMed

Carroll, Matthew B; Smith, Derek M; Shaak, Thomas L

2017-03-01

It remains unclear why the dose of xanthine oxidase inhibitors (XOI) allopurinol or febuxostat varies among patients though they reach similar serum uric acid (SUA) goal. We pursued genomic sequencing of XOI metabolism and clearance genes to identify single-nucleotide polymorphisms (SNPs) relate to differences in XOI dose. Subjects with a diagnosis of Gout based on the 1977 American College of Rheumatology Classification Criteria for the disorder, who were on stable doses of a XOI, and who were at their goal SUA level, were enrolled. The primary outcome was relationship between SNPs in any of these genes to XOI dose. The secondary outcome was relationship between SNPs and change in pre- and post-treatment SUA. We enrolled 100 subjects. The average patient age was 68.6 ± 10.6 years old. Over 80% were men and 77% were Caucasian. One SNP was associated with a higher XOI dose: rs75995567 (p = 0.031). Two SNPs were associated with 300 mg daily of allopurinol: rs11678615 (p = 0.022) and rs3731722 on Aldehyde Oxidase (AO) (His1297Arg) (p = 0.001). Two SNPs were associated with a lower dose of allopurinol: rs1884725 (p = 0.033) and rs34650714 (p = 0.006). For the secondary outcome, rs13415401 was the only SNP related to a smaller mean SUA change. Ten SNPs were identified with a larger change in SUA. Though multiple SNPs were identified in the primary and secondary outcomes of this study, rs3731722 is known to alter catalytic function for some aldehyde oxidase substrates.

Recurrent/moderate hypoglycemia induces hippocampal dendritic injury, microglial activation, and cognitive impairment in diabetic rats

PubMed Central

2012-01-01

Background Recurrent/moderate (R/M) hypoglycemia is common in type 1 diabetes. Although mild or moderate hypoglycemia is not life-threatening, if recurrent, it may cause cognitive impairment. In the present study, we sought to determine whether R/M hypoglycemia leads to neuronal death, dendritic injury, or cognitive impairment. Methods The experiments were conducted in normal and in diabetic rats. Rats were subjected to moderate hypoglycemia by insulin without anesthesia. Oxidative stress was evaluated by 4-Hydroxy-2-nonenal immunostaining and neuronal death was determined by Fluoro-Jade B staining 7 days after R/M hypoglycemia. To test whether oxidative injury caused by NADPH oxidase activation, an NADPH oxidase inhibitor, apocynin, was used. Cognitive function was assessed by Barnes maze and open field tests at 6 weeks after R/M hypoglycemia. Results The present study found that oxidative injury was detected in the dendritic area of the hippocampus after R/M hypoglycemia. Sparse neuronal death was found in the cortex, but no neuronal death was detected in the hippocampus. Significant cognitive impairment and thinning of the CA1 dendritic region was detected 6 weeks after hypoglycemia. Oxidative injury, cognitive impairment, and hippocampal thinning after R/M hypoglycemia were more severe in diabetic rats than in non-diabetic rats. Oxidative damage in the hippocampal CA1 dendritic area and microglial activation were reduced by the NADPH oxidase inhibitor, apocynin. Conclusion The present study suggests that oxidative injury of the hippocampal CA1 dendritic region by R/M hypoglycemia is associated with chronic cognitive impairment in diabetic patients. The present study further suggests that NADPH oxidase inhibition may prevent R/M hypoglycemia-induced hippocampal dendritic injury. PMID:22830525

Mitochondrial complex I and NAD(P)H oxidase are major sources of exacerbated oxidative stress in pressure-overloaded ischemic-reperfused hearts.

PubMed

Mozaffari, Mahmood S; Baban, Babak; Liu, Jun Yao; Abebe, Worku; Sullivan, Jennifer C; El-Marakby, Ahmed

2011-03-01

We tested the hypothesis that pressure overload exacerbates oxidative stress associated with augmented mitochondrial permeability transition (MPT) pore opening and cell death in ischemic-reperfused hearts. Pressure overload decreased the level of reduced glutathione but increased nitrotyrosine and 8-hydroxydeoxyguanosine levels in ischemic-reperfused hearts. The activity of catalase, but not superoxide dismutase (SOD), was lower in ischemic-reperfused hearts perfused at higher pressure. Mitochondria from ischemic-reperfused hearts subjected to higher perfusion pressure displayed significantly greater [³H]-2-deoxyglucose-6-P entrapment suggestive of greater MPT pore opening and consistent with greater necrosis and apoptosis. Tempol (SOD mimetic) reduced infarct size in both groups but it remained greater in the higher pressure group. By contrast, uric acid (peroxynitrite scavenger) markedly reduced infarct size at higher pressure, effectively eliminating the differential between the two groups. Inhibition of xanthine oxidase, with allopurinol, reduced infarct size but did not eliminate the differential between the two groups. However, amobarbital (inhibitor of mitochondrial complex I) or apocynin [inhibitor of NAD(P)H oxidase] reduced infarct size at both pressures and also abrogated the differential between the two groups. Consistent with the effect of apocynin, pressure-overloaded hearts displayed significantly higher NAD(P)H oxidase activity. Furthermore, pressure-overloaded hearts displayed increased nitric oxide synthase activity which, along with increased propensity to superoxide generation, may underlie uric acid-induced cardioprotection. In conclusion, increased oxidative and nitrosative stress, coupled with lack of augmented SOD and catalase activities, contributes importantly to the exacerbating impact of pressure overload on MPT pore opening and cell death in ischemic-reperfused hearts.

Contrasting responses of photosynthesis to salt stress in the glycophyte Arabidopsis and the halophyte thellungiella: role of the plastid terminal oxidase as an alternative electron sink.

PubMed

Stepien, Piotr; Johnson, Giles N

2009-02-01

The effects of short-term salt stress on gas exchange and the regulation of photosynthetic electron transport were examined in Arabidopsis (Arabidopsis thaliana) and its salt-tolerant close relative Thellungiella (Thellungiella halophila). Plants cultivated on soil were challenged for 2 weeks with NaCl. Arabidopsis showed a much higher sensitivity to salt than Thellungiella; while Arabidopsis plants were unable to survive exposure to greater than 150 mM salt, Thellugiella could tolerate concentrations as high as 500 mM with only minimal effects on gas exchange. Exposure of Arabidopsis to sublethal salt concentrations resulted in stomatal closure and inhibition of CO2 fixation. This lead to an inhibition of electron transport though photosystem II (PSII), an increase in cyclic electron flow involving only PSI, and increased nonphotochemical quenching of chlorophyll fluorescence. In contrast, in Thellungiella, although gas exchange was marginally inhibited by high salt and PSI was unaffected, there was a large increase in electron flow involving PSII. This additional electron transport activity is oxygen dependent and sensitive to the alternative oxidase inhibitor n-propyl gallate. PSII electron transport in Thellungiella showed a reduced sensitivity to 2'-iodo-6-isopropyl-3-methyl-2',4,4'-trinitrodiphenylether, an inhibitor of the cytochrome b6f complex. At the same time, we observed a substantial up-regulation of a protein reacting with antibodies raised against the plastid terminal oxidase. No such up-regulation was seen in Arabidopsis. We conclude that in salt-stressed Thellungiella, plastid terminal oxidase acts as an alternative electron sink, accounting for up to 30% of total PSII electron flow.

Resveratrol prevents high glucose-induced epithelial-mesenchymal transition in renal tubular epithelial cells by inhibiting NADPH oxidase/ROS/ERK pathway.

PubMed

He, Ting; Guan, Xu; Wang, Song; Xiao, Tangli; Yang, Ke; Xu, Xinli; Wang, Junping; Zhao, Jinghong

2015-02-15

Resveratrol (RSV) is reported to have renoprotective activity against diabetic nephropathy, while the mechanisms underlying its function have not been fully elucidated. In this study, we investigate the effect and related mechanism of RSV against high glucose-induced epithelial to mesenchymal transition (EMT) in human tubular epithelial cells (HK-2). A typical EMT is induced by high glucose in HK-2 cells, accompanied by increased levels of reactive oxygen species (ROS). RSV exhibits a strong ability to inhibit high glucose-induced EMT by decreasing intracellular ROS levels via down-regulation of NADPH oxidase subunits NOX1 and NOX4. The activation of extracellular signal-regulated kinase (ERK1/2) is found to be involved in high glucose-induced EMT in HK-2 cells. RSV, like NADPH oxidase inhibitor diphenyleneiodonium, can block ERK1/2 activation induced by high glucose. Our results demonstrate that RSV is a potent agent against high glucose-induced EMT in renal tubular cells via inhibition of NADPH oxidase/ROS/ERK1/2 pathway. Copyright © 2014 Elsevier Ireland Ltd. All rights reserved.

[Panic disorder: clinical phenomena and treatment options].

PubMed

Sivolap, Yu P

2017-01-01

Panic disorder is a common mental disease with high psychiatric comorbidity. It is considered that a combination of genetic predisposition and a special psychic vulnerability plays a key role in the occurrence of panic disorder. Clinically proven efficacy in the treatment of panic disorder have benzodiazepines, tricyclic antidepressants, monoamine oxidase inhibitors, selective serotonin reuptake inhibitors and selective serotonin and norepinephrine reuptake inhibitors; antidepressants from other pharmaceutical groups are also used. Selective serotonin reuptake inhibitors are the first line medicines in the treatment of panic disorder. Atypical antipsychotics may be used for the therapy augmentation in addition to first line drugs. Psychotherapy is used along with medications, and a combination of pharmacotherapy and cognitive behavioral therapy is the best method of treatment.

The carbanion of nitroethane is an inhibitor of, and not a substrate for, flavocytochrome b2 [L-(+)-lactate dehydrogenase

PubMed Central

Genet, R; Lederer, F

1990-01-01

Although nitroethane does not bind to the active site of flavocytochrome b2, its anion, ethane nitronate, behaves as a competitive inhibitor, with a Ki of 2.2 mM. No electron transfer can be detected between the nitronate and the enzyme, in contrast with the observations of other workers on D-amino acid oxidase. Propionate is a competitive inhibitor, with a Ki of 28 mM. The significance of these results with respect to the proposed carbanion mechanism and the putative existence of a covalent enzyme-substrate intermediate is discussed. PMID:2178603

Role of the photosynthetic electron transfer chain in electrogenic activity of cyanobacteria.

PubMed

Pisciotta, John M; Zou, Yongjin; Baskakov, Ilia V

2011-07-01

Certain anaerobic bacteria, termed electrogens, produce an electric current when electrons from oxidized organic molecules are deposited to extracellular metal oxide acceptors. In these heterotrophic "metal breathers", the respiratory electron transport chain (R-ETC) works in concert with membrane-bound cytochrome oxidases to transfer electrons to the extracellular acceptors. The diversity of bacteria able to generate an electric current appears more widespread than previously thought, and aerobic phototrophs, including cyanobacteria, possess electrogenic activity. However, unlike heterotrophs, cyanobacteria electrogenic activity is light dependent, which suggests that a novel pathway could exist. To elucidate the electrogenic mechanism of cyanobacteria, the current studies used site-specific inhibitors to target components of the photosynthetic electron transport chain (P-ETC) and cytochrome oxidases. Here, we show that (1) P-ETC and, particularly, water photolysed by photosystem II (PSII) is the source of electrons discharged to the environment by illuminated cyanobacteria, and (2) water-derived electrons are transmitted from PSII to extracellular electron acceptors via plastoquinone and cytochrome bd quinol oxidase. Two cyanobacterial genera (Lyngbya and Nostoc) displayed very similar electrogenic responses when treated with P-ETC site-specific inhibitors, suggesting a conserved electrogenic pathway. We propose that in cyanobacteria, electrogenic activity may represent a form of overflow metabolism to protect cells under high-intensity light. This study offers insight into electron transfer between phototrophic microorganisms and the environment and expands our knowledge into biologically based mechanisms for harnessing solar energy.

Possible involvement of 12-lipoxygenase activation in glucose-deprivation/reload-treated neurons.

PubMed

Nagasawa, Kazuki; Kakuda, Taichi; Higashi, Youichirou; Fujimoto, Sadaki

2007-12-18

The aim of this study was to clarify whether 12-lipoxygenase (12-LOX) activation was involved in reactive oxygen species (ROS) generation, extensive poly(ADP-ribose) polymerase (PARP) activation and neuronal death induced by glucose-deprivation, followed by glucose-reload (GD/R). The decrease of neuronal viability and accumulation of poly(ADP-ribose) induced by GD/R were prevented 3-aminobenzamide, a representative PARP inhibitor, demonstrating this treatment protocol caused the same oxidative stress with the previously reported one. The PARP activation, ROS generation and decrease of neuron viability induced by GD/R treatment were almost completely abolished by an extracellular zinc chelator, CaEDTA. p47(phox), a cytosolic component of NADPH oxidase was translocated the membrane fraction by GD/R, indicating its activation, but it did not generate detectable ROS. Surprisingly, pharmacological inhibition of NADPH oxidase with apocynin and AEBSF further decreased the decreased neuron viability induced by GD/R. On the other hand, AA861, a 12-LOX inhibitor, prevented ROS generation and decrease of neuron viability caused by GD/R. Interestingly, an antioxidant, N-acetyl-l-cysteine rescued the neurons from GD/R-induced oxidative stress, implying effectiveness of antioxidant administration. These findings suggested that activation of 12-LOX, but not NADPH oxidase, following to zinc release might play an important role in ROS generation and decrease of viability in GD/R-treated neurons.

Mendelian randomization analysis associates increased serum urate, due to genetic variation in uric acid transporters, with improved renal function.

PubMed

Hughes, Kim; Flynn, Tanya; de Zoysa, Janak; Dalbeth, Nicola; Merriman, Tony R

2014-02-01

Increased serum urate predicts chronic kidney disease independent of other risk factors. The use of xanthine oxidase inhibitors coincides with improved renal function. Whether this is due to reduced serum urate or reduced production of oxidants by xanthine oxidase or another physiological mechanism remains unresolved. Here we applied Mendelian randomization, a statistical genetics approach allowing disentangling of cause and effect in the presence of potential confounding, to determine whether lowering of serum urate by genetic modulation of renal excretion benefits renal function using data from 7979 patients of the Atherosclerosis Risk in Communities and Framingham Heart studies. Mendelian randomization by the two-stage least squares method was done with serum urate as the exposure, a uric acid transporter genetic risk score as instrumental variable, and estimated glomerular filtration rate and serum creatinine as the outcomes. Increased genetic risk score was associated with significantly improved renal function in men but not in women. Analysis of individual genetic variants showed the effect size associated with serum urate did not correlate with that associated with renal function in the Mendelian randomization model. This is consistent with the possibility that the physiological action of these genetic variants in raising serum urate correlates directly with improved renal function. Further studies are required to understand the mechanism of the potential renal function protection mediated by xanthine oxidase inhibitors.

Granzyme B of cytotoxic T cells induces extramitochondrial reactive oxygen species production via caspase-dependent NADPH oxidase activation.

PubMed

Aguiló, Juan I; Anel, Alberto; Catalán, Elena; Sebastián, Alvaro; Acín-Pérez, Rebeca; Naval, Javier; Wallich, Reinhard; Simon, Markus M; Pardo, Julián

2010-07-01

Induction of reactive oxygen species (ROS) is a hallmark of granzyme B (gzmB)-mediated pro-apoptotic processes and target cell death. However, it is unclear to what extent the generated ROS derive from mitochondrial and/or extra-mitochondrial sources. To clarify this point, we have produced a mutant EL4 cell line, termed EL4-rho(0), which lacks mitochondrial DNA, associated with a decreased mitochondrial membrane potential and a defective ROS production through the electron transport chain of oxidative phosphorylation. When incubated with either recombinant gzmB plus streptolysin or ex vivo gzmB(+) cytotoxic T cells, EL4-rho(0) cells showed phosphatydylserine translocation, caspase 3 activation, Bak conformational change, cytochrome c release and apoptotic morphology comparable to EL4 cells. Moreover, EL4-rho(0) cells produced ROS at levels similar to EL4 under these conditions. GzmB-mediated ROS production was almost totally abolished in both cell lines by the pan-caspase inhibitor, Z-VAD-fmk. However, addition of apocynin, a specific inhibitor of nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, led to a significant reduction of ROS production and cell death only in EL4-rho(0) but not EL4 cells. These data suggest that gzmB-induced cell death is accompanied by a caspase-dependent pathway of extra-mitochondrial ROS production, most probably through activation of NADPH oxidase.

The trimethylammonium headgroup of choline is a major determinant for substrate binding and specificity in choline oxidase.

PubMed

Gadda, Giovanni; Powell, Nichole L N; Menon, Prashanthi

2004-10-15

Choline oxidase catalyzes the oxidation of choline to glycine betaine via two sequential flavin-linked transfers of hydride equivalents to molecular oxygen and formation of a betaine aldehyde intermediate. In the present study, choline and glycine betaine analogs were used as substrates and inhibitors for the enzyme to investigate the structural determinants that are relevant for substrate recognition and specificity. Competitive inhibition patterns with respect to choline were determined for a number of substituted amines at pH 6.5 and 25 degrees C. The Kis values for the carboxylate-containing ligands glycine betaine, N,N-dimethylglycine, and N-methylglycine increased monotonically with decreasing number of methyl groups, consistent with the trimethylammonium portion of the ligand being important for binding. In contrast, the acetate portion of glycine betaine did not contribute to binding, as suggested by lack of changes in the Kis values upon substituting glycine betaine with inhibitors containing methyl, ethyl, allyl, and 2-amino-ethyl side chains. In agreement with the inhibition data, the specificity of the enzyme for the organic substrate (kcat/Km value) decreased when N,N-dimethylethanolamine, N-methylethanolamine, and the isosteric substrate 3,3-dimethyl-1-butanol were used as substrate instead of choline; a contribution of approximately 7 kcal mol(-1) toward substrate discrimination was estimated for the interaction of the trimethylammonium portion of the substrate with the active site of choline oxidase.

Association analysis of the functional MAOA gene promoter and MAOB gene intron 13 polymorphisms in tension type headache patients.

PubMed

Edgnülü, Tuba G; Özge, Aynur; Erdal, Nurten; Kuru, Oktay; Erdal, Mehmet E

2014-01-01

Monoamine oxidase (MAO) enzymes play an important role in the etiology of many neurological diseases. Tension type headache (TTH) treatments contain inhibitors for selective re-uptake of serotonin and monoamine oxidase inhibitors. MAO (EC 1.4.3.4) has two isoenzymes known as MAOA and MAOB. A promoter polymorphism of a variable number of tandem repeats (VNTR) in the MAOA gene seems to affect MAOA transcriptional activity in vitro. Also, G/A polymorphism in intron 13 (rs1799836) of the MAOB gene have been previously found to be associated with the variability of MAOB enzyme activity. The aim of our study was to investigate a possible association of monoamine oxidase (MAOA and MAOB) gene polymorphisms in tension type headache. MAO gene polymorphisms were examined in a group of 120 TTH patients and in another 168 unrelated healthy volunteers (control group). MAOA promoter and MAOB intron 13 polymorphisms were genotyped using PCR-based methods. An overall comparison between the genotype of MAOA and MAOB genes and allele frequencies of the patients and the control group did not reveal any statistically significant difference between the patients and the control group (p=0.162). Factors like estrogen dosage, the limited number of male patients and other genes' neurotransmitters involved in the etiology of TTH could be responsible for our non-significant results.

The NADPH oxidase inhibitor apocynin induces nitric oxide synthesis via oxidative stress

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

Riganti, Chiara; Costamagna, Costanzo; Doublier, Sophie

We have recently shown that apocynin elicits an oxidative stress in N11 mouse glial cells and other cell types. Here we report that apocynin increased the accumulation of nitrite, the stable derivative of nitric oxide (NO), in the extracellular medium of N11 cell cultures, and the NO synthase (NOS) activity in cell lysates. The increased synthesis of NO was associated with increased expression of inducible NOS (iNOS) mRNA, increased nuclear translocation of the redox-sensitive transcription factor NF-{kappa}B and decreased intracellular level of its inhibitor IkB{alpha}. These effects, accompanied by increased production of H{sub 2}O{sub 2}, were very similar to thosemore » observed after incubation with bacterial lipopolysaccharide (LPS) and were inhibited by catalase. These results suggest that apocynin, similarly to LPS, induces increased NO synthesis by eliciting a generation of reactive oxygen species (ROS), which in turn causes NF-{kappa}B activation and increased expression of iNOS. Therefore, the increased bioavailability of NO reported in the literature after in vivo or in vitro treatments with apocynin might depend, at least partly, on the drug-elicited induction of iNOS, and not only on the inhibition of NADPH oxidase and the subsequent decreased scavenging of NO by oxidase-derived ROS, as it is often supposed.« less

Inhibitory effects of cardols and related compounds on superoxide anion generation by xanthine oxidase.

PubMed

Masuoka, Noriyoshi; Nihei, Ken-ichi; Maeta, Ayami; Yamagiwa, Yoshiro; Kubo, Isao

2015-01-01

5-Pentadecatrienylresorcinol, isolated from cashew nuts and commonly known as cardol (C₁₅:₃), prevented the generation of superoxide radicals catalysed by xanthine oxidase without the inhibition of uric acid formation. The inhibition kinetics did not follow the Michelis-Menten equation, but instead followed the Hill equation. Cardol (C₁₀:₀) also inhibited superoxide anion generation, but resorcinol and cardol (C₅:₀) did not inhibit superoxide anion generation. The related compounds 3,5-dihydroxyphenyl alkanoates and alkyl 2,4-dihydroxybenzoates, had more than a C9 chain, cooperatively inhibited but alkyl 3,5-dihydroxybenzoates, regardless of their alkyl chain length, did not inhibit the superoxide anion generation. These results suggested that specific inhibitors for superoxide anion generation catalysed by xanthine oxidase consisted of an electron-rich resorcinol group and an alkyl chain having longer than C9 chain. Copyright © 2014 Elsevier Ltd. All rights reserved.

[Hepatic allopurinol oxidizing enzyme in mice].

PubMed

Huh, K; Iwata, H; Yamamoto, I

1975-03-01

The relationship between allopurinol oxidizing enzyme and aldehyde oxidase was investaged in mice. The oxidation of both N-methylnicotinamide and allopurinol appears to be catalized by a single enzyme, aldehyde oxidase (aldehyde-oxygen oxidoreductase EC, 1.2.3.1.). This conclusion is based on the following evidence; The postnatal changes of allopurinol and N-methylnicotinamide oxidizing activities were similar during growth and the levels of both activities increased in a parallel fashion upon the attainment of sexual maturity. The rates of loss of the activities of both enzymes by heat denaturation as well as dexamethasone administration were similar. The inhibitors of allopurinol oxidizing enzyme also suppressed N-methylnicotinamide oxidation. Competition of N-methylnicotineamide and allopurinol for oxidation was demonstrated. The rate of increase of the activities in both enzymes was almost parallel during each step of the purification from mouse liver supernatant. It was ascertained that xanthine oxidase in the enzyme preparation does not influence allopurinol oxidation.

The neutron structure of urate oxidase resolves a long-standing mechanistic conundrum and reveals unexpected changes in protonation.

PubMed

Oksanen, Esko; Blakeley, Matthew P; El-Hajji, Mohamed; Ryde, Ulf; Budayova-Spano, Monika

2014-01-01

Urate oxidase transforms uric acid to 5-hydroxyisourate without the help of cofactors, but the catalytic mechanism has remained enigmatic, as the protonation state of the substrate could not be reliably deduced. We have determined the neutron structure of urate oxidase, providing unique information on the proton positions. A neutron crystal structure inhibited by a chloride anion at 2.3 Å resolution shows that the substrate is in fact 8-hydroxyxanthine, the enol tautomer of urate. We have also determined the neutron structure of the complex with the inhibitor 8-azaxanthine at 1.9 Å resolution, showing the protonation states of the K10-T57-H256 catalytic triad. Together with X-ray data and quantum chemical calculations, these structures allow us to identify the site of the initial substrate protonation and elucidate why the enzyme is inhibited by a chloride anion.

Inhibition of S-adenosylmethionine decarboxylase and diamine oxidase activities by analogues of methylglyoxal bis(guanylhydrazone) and their cellular uptake during lymphocyte activation.

PubMed Central

Jänne, J; Morris, D R

1984-01-01

Several congeners of methylglyoxal bis(guanylhydrazone) were tested for their ability to inhibit eukaryotic putrescine-activated S-adenosylmethionine decarboxylase (EC 4.1.1.50) and intestinal diamine oxidase (EC 1.4.3.6). All the compounds tested, namely methylglyoxal bis(guanylhydrazone), ethylglyoxal bis(guanylhydrazone), dimethylglyoxal bis(guanylhydrazone) and the di-N"-methyl derivative of methylglyoxal bis(guanylhydrazone), were strong inhibitors of both yeast and mouse liver adenosylmethionine decarboxylase activity in vitro. The enzyme from both sources was most powerfully inhibited by ethylglyoxal bis(guanylhydrazone). All the diguanidines likewise inhibited diamine oxidase activity in vitro. The maximum intracellular concentrations of the ethyl and dimethylated analogues achieved in activated lymphocytes were only about one-fifth of that of the parent compound. However, both derivatives appeared to utilize the polyamine-carrier system, as indicated by competition experiments with spermidine. PMID:6426466

Inhibition of S-adenosylmethionine decarboxylase and diamine oxidase activities by analogues of methylglyoxal bis(guanylhydrazone) and their cellular uptake during lymphocyte activation.

PubMed

Jänne, J; Morris, D R

1984-03-15

Several congeners of methylglyoxal bis(guanylhydrazone) were tested for their ability to inhibit eukaryotic putrescine-activated S-adenosylmethionine decarboxylase (EC 4.1.1.50) and intestinal diamine oxidase (EC 1.4.3.6). All the compounds tested, namely methylglyoxal bis(guanylhydrazone), ethylglyoxal bis(guanylhydrazone), dimethylglyoxal bis(guanylhydrazone) and the di-N"-methyl derivative of methylglyoxal bis(guanylhydrazone), were strong inhibitors of both yeast and mouse liver adenosylmethionine decarboxylase activity in vitro. The enzyme from both sources was most powerfully inhibited by ethylglyoxal bis(guanylhydrazone). All the diguanidines likewise inhibited diamine oxidase activity in vitro. The maximum intracellular concentrations of the ethyl and dimethylated analogues achieved in activated lymphocytes were only about one-fifth of that of the parent compound. However, both derivatives appeared to utilize the polyamine-carrier system, as indicated by competition experiments with spermidine.

Phenyl- and benzylurea cytokinins as competitive inhibitors of cytokinin oxidase/dehydrogenase: a structural study.

PubMed

Kopecný, David; Briozzo, Pierre; Popelková, Hana; Sebela, Marek; Koncitíková, Radka; Spíchal, Lukás; Nisler, Jaroslav; Madzak, Catherine; Frébort, Ivo; Laloue, Michel; Houba-Hérin, Nicole

2010-08-01

Cytokinin oxidase/dehydrogenase (CKO) is a flavoenzyme, which irreversibly degrades the plant hormones cytokinins and thereby participates in their homeostasis. Several synthetic cytokinins including urea derivatives are known CKO inhibitors but structural data explaining enzyme-inhibitor interactions are lacking. Thus, an inhibitory study with numerous urea derivatives was undertaken using the maize enzyme (ZmCKO1) and the crystal structure of ZmCKO1 in a complex with N-(2-chloro-pyridin-4-yl)-N'-phenylurea (CPPU) was solved. CPPU binds in a planar conformation and competes for the same binding site with natural substrates like N(6)-(2-isopentenyl)adenine (iP) and zeatin (Z). Nitrogens at the urea backbone are hydrogen bonded to the putative active site base Asp169. Subsequently, site-directed mutagenesis of L492 and E381 residues involved in the inhibitor binding was performed. The crystal structures of L492A mutant in a complex with CPPU and N-(2-chloro-pyridin-4-yl)-N'-benzylurea (CPBU) were solved and confirm the importance of a stacking interaction between the 2-chloro-4-pyridinyl ring of the inhibitor and the isoalloxazine ring of the FAD cofactor. Amino derivatives like N-(2-amino-pyridin-4-yl)-N'-phenylurea (APPU) inhibited ZmCKO1 more efficiently than CPPU, as opposed to the inhibition of E381A/S mutants, emphasizing the importance of this residue for inhibitor binding. As highly specific CKO inhibitors without undesired side effects are of major interest for physiological studies, all studied compounds were further analyzed for cytokinin activity in the Amaranthus bioassay and for binding to the Arabidopsis cytokinin receptors AHK3 and AHK4. By contrast to CPPU itself, APPU and several benzylureas bind only negligibly to the receptors and exhibit weak cytokinin activity. Copyright 2010 Elsevier Masson SAS. All rights reserved.

Cooperation of imipramine blue and tyrosine kinase blockade demonstrates activity against chronic myeloid leukemia

PubMed Central

Laidlaw, Kamilla M.E.; Berhan, Samuel; Liu, Suhu; Silvestri, Giovannino; Holyoake, Tessa L.; Frank, David A.; Aggarwal, Bharat; Bonner, Michael Y.; Perrotti, Danilo

2016-01-01

The use of tyrosine kinase inhibitors (TKI), including nilotinib, has revolutionized the treatment of chronic myeloid leukemia (CML). However current unmet clinical needs include combating activation of additional survival signaling pathways in persistent leukemia stem cells after long-term TKI therapy. A ubiquitous signaling alteration in cancer, including CML, is activation of reactive oxygen species (ROS) signaling, which may potentiate stem cell activity and mediate resistance to both conventional chemotherapy and targeted inhibitors. We have developed a novel nicotinamide adenine dinucleotide phosphate (NADPH) oxidase inhibitor, imipramine blue (IB) that targets ROS generation. ROS levels are known to be elevated in CML with respect to normal hematopoietic stem/progenitor cells and not corrected by TKI. We demonstrate that IB has additive benefit with nilotinib in inhibiting proliferation, viability, and clonogenic function of TKI-insensitive quiescent CD34+ CML chronic phase (CP) cells while normal CD34+ cells retained their clonogenic capacity in response to this combination therapy in vitro. Mechanistically, the pro-apoptotic activity of IB likely resides in part through its dual ability to block NF-κB and re-activate the tumor suppressor protein phosphatase 2A (PP2A). Combining BCR-ABL1 kinase inhibition with NADPH oxidase blockade may be beneficial in eradication of CML and worthy of further investigation. PMID:27438151

JNK and NADPH Oxidase Involved in Fluoride-Induced Oxidative Stress in BV-2 Microglia Cells

PubMed Central

Yan, Ling; Liu, Shengnan; Wang, Chen; Wang, Fei; Song, Yingli; Yan, Nan; Xi, Shuhua; Liu, Ziyou; Sun, Guifan

2013-01-01

Excessive fluoride may cause central nervous system (CNS) dysfunction, and oxidative stress is a recognized mode of action of fluoride toxicity. In CNS, activated microglial cells can release more reactive oxygen species (ROS), and NADPH oxidase (NOX) is the major enzyme for the production of extracellular superoxide in microglia. ROS have been characterized as an important secondary messenger and modulator for various mammalian intracellular signaling pathways, including the MAPK pathways. In this study we examined ROS production and TNF-α, IL-1β inflammatory cytokines releasing, and the expression of MAPKs in BV-2 microglia cells treated with fluoride. We found that fluoride increased JNK phosphorylation level of BV-2 cells and pretreatment with JNK inhibitor SP600125 markedly reduced the levels of intracellular O2 ·− and NO. NOX inhibitor apocynin and iNOS inhibitor SMT dramatically decreased NaF-induced ROS and NO generations, respectively. Antioxidant melatonin (MEL) resulted in a reduction in JNK phosphorylation in fluoride-stimulated BV-2 microglia. The results confirmed that NOX and iNOS played an important role in fluoride inducing oxidative stress and NO production and JNK took part in the oxidative stress induced by fluoride and meanwhile also could be activated by ROS in fluoride-treated BV-2 cells. PMID:24072958

Exploration of a Library of 3,4-(Methylenedioxy)aniline-Derived Semicarbazones as Dual Inhibitors of Monoamine Oxidase and Acetylcholinesterase: Design, Synthesis, and Evaluation.

PubMed

Tripathi, Rati K P; Rai, Gopal K; Ayyannan, Senthil R

2016-06-06

A library of 3,4-(methylenedioxy)aniline-derived semicarbazones was designed, synthesized, and evaluated as monoamine oxidase (MAO) and acetylcholinesterase (AChE) inhibitors for the treatment of neurodegenerative diseases. Most of the new compounds selectively inhibited MAO-B and AChE, with IC50 values in the micro- or nanomolar ranges. Compound 16, 1-(2,6-dichlorobenzylidene)-4-(benzo[1,3]dioxol-5-yl)semicarbazide presented a balanced multifunctional profile of MAO-A (IC50 =4.52±0.032 μm), MAO-B (IC50 =0.059±0.002 μm), and AChE (IC50 =0.0087±0.0002 μm) inhibition without neurotoxicity. Kinetic studies revealed that compound 16 exhibits competitive and reversible inhibition against MAO-A and MAO-B, and mixed-type inhibition against AChE. Molecular docking studies further revealed insight into the possible interactions within the enzyme-inhibitor complexes. The most active compounds were found to interact with the enzymes through hydrogen bonding and hydrophobic interactions. Additionally, in silico molecular properties and ADME properties of the synthesized compounds were calculated to explore their drug-like characteristics. © 2016 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Febuxostat, an Inhibitor of Xanthine Oxidase, Suppresses Lipopolysaccharide-Induced MCP-1 Production via MAPK Phosphatase-1-Mediated Inactivation of JNK

PubMed Central

Nomura, Johji; Busso, Nathalie; Ives, Annette; Tsujimoto, Syunsuke; Tamura, Mizuho; So, Alexander; Yamanaka, Yoshihiro

2013-01-01

Excess reactive oxygen species (ROS) formation can trigger various pathological conditions such as inflammation, in which xanthine oxidase (XO) is one major enzymatic source of ROS. Although XO has been reported to play essential roles in inflammatory conditions, the molecular mechanisms underlying the involvement of XO in inflammatory pathways remain unclear. Febuxostat, a selective and potent inhibitor of XO, effectively inhibits not only the generation of uric acid but also the formation of ROS. In this study, therefore, we examined the effects of febuxostat on lipopolysaccharide (LPS)-mediated inflammatory responses. Here we show that febuxostat suppresses LPS-induced MCP-1 production and mRNA expression via activating MAPK phosphatase-1 (MKP-1) which, in turn, leads to dephosphorylation and inactivation of JNK in macrophages. Moreover, these effects of febuxostat are mediated by inhibiting XO-mediated intracellular ROS production. Taken together, our data suggest that XO mediates LPS-induced phosphorylation of JNK through ROS production and MKP-1 inactivation, leading to MCP-1 production in macrophages. These studies may bring new insights into the novel role of XO in regulating inflammatory process through MAPK phosphatase, and demonstrate the potential use of XO inhibitor in modulating the inflammatory processes. PMID:24086554

Chemotherapy-Induced Monoamine Oxidase Expression in Prostate Carcinoma Functions as a Cytoprotective Resistance Enzyme and Associates with Clinical Outcomes

PubMed Central

Huang, Chung-Ying; Harris, William P.; Sim, Hong Gee; Lucas, Jared M.; Coleman, Ilsa; Higano, Celestia S.; Gulati, Roman; True, Lawrence D.; Vessella, Robert; Lange, Paul H.; Garzotto, Mark; Beer, Tomasz M.; Nelson, Peter S.

2014-01-01

To identify molecular alterations in prostate cancers associating with relapse following neoadjuvant chemotherapy and radical prostatectomy patients with high-risk localized prostate cancer were enrolled into a phase I-II clinical trial of neoadjuvant chemotherapy with docetaxel and mitoxantrone followed by prostatectomy. Pre-treatment prostate tissue was acquired by needle biopsy and post-treatment tissue was acquired by prostatectomy. Prostate cancer gene expression measurements were determined in 31 patients who completed 4 cycles of neoadjuvant chemotherapy. We identified 141 genes with significant transcript level alterations following chemotherapy that associated with subsequent biochemical relapse. This group included the transcript encoding monoamine oxidase A (MAOA). In vitro, cytotoxic chemotherapy induced the expression of MAOA and elevated MAOA levels enhanced cell survival following docetaxel exposure. MAOA activity increased the levels of reactive oxygen species and increased the expression and nuclear translocation of HIF1α. The suppression of MAOA activity using the irreversible inhibitor clorgyline augmented the apoptotic responses induced by docetaxel. In summary, we determined that the expression of MAOA is induced by exposure to cytotoxic chemotherapy, increases HIF1α, and contributes to docetaxel resistance. As MAOA inhibitors have been approved for human use, regimens combining MAOA inhibitors with docetaxel may improve clinical outcomes. PMID:25198178

Induction of defence gene expression by oligogalacturonic acid requires increases in both cytosolic calcium and hydrogen peroxide in Arabidopsis thaliana.

PubMed

Hu, Xiang Yang; Neill, Steven J; Cai, Wei Ming; Tang, Zhang Cheng

2004-06-01

Responses to oligogalacturonic acid (OGA) were determined in transgenic Arabidopsis thaliana seedlings expressing the calcium reporter protein aequorin. OGA stimulated a rapid, substantial and transient increase in the concentration of cytosolic calcium ([Ca2+]cyt) that peaked after ca. 15 s. This increase was dose-dependent, saturating at ca. 50 ug Gal equiv/ml of OGA. OGA also stimulated a rapid generation of H2O2. A small, rapid increase in H2O2 content was followed by a much larger oxidative burst, with H2O2 content peaking after ca. 60 min and declining thereafter. Induction of the oxidative burst by OGA was also dose-dependent, with a maximum response again being achieved at ca. 50 ug Gal equiv/mL. Inhibitors of calcium fluxes inhibited both increases in [Ca2+]cyt and [H2O2], whereas inhibitors of NADPH oxidase blocked only the oxidative burst. OGA increased strongly the expression of the defence-related genes CHS, GST, PAL and PR-1. This induction was suppressed by inhibitors of calcium flux or NADPH oxidase, indicating that increases in both cytosolic calcium and H2O2 are required for OGA-induced gene expression.

Chemotherapy-induced monoamine oxidase expression in prostate carcinoma functions as a cytoprotective resistance enzyme and associates with clinical outcomes.

PubMed

Gordon, Ryan R; Wu, Mengchu; Huang, Chung-Ying; Harris, William P; Sim, Hong Gee; Lucas, Jared M; Coleman, Ilsa; Higano, Celestia S; Gulati, Roman; True, Lawrence D; Vessella, Robert; Lange, Paul H; Garzotto, Mark; Beer, Tomasz M; Nelson, Peter S

2014-01-01

To identify molecular alterations in prostate cancers associating with relapse following neoadjuvant chemotherapy and radical prostatectomy patients with high-risk localized prostate cancer were enrolled into a phase I-II clinical trial of neoadjuvant chemotherapy with docetaxel and mitoxantrone followed by prostatectomy. Pre-treatment prostate tissue was acquired by needle biopsy and post-treatment tissue was acquired by prostatectomy. Prostate cancer gene expression measurements were determined in 31 patients who completed 4 cycles of neoadjuvant chemotherapy. We identified 141 genes with significant transcript level alterations following chemotherapy that associated with subsequent biochemical relapse. This group included the transcript encoding monoamine oxidase A (MAOA). In vitro, cytotoxic chemotherapy induced the expression of MAOA and elevated MAOA levels enhanced cell survival following docetaxel exposure. MAOA activity increased the levels of reactive oxygen species and increased the expression and nuclear translocation of HIF1α. The suppression of MAOA activity using the irreversible inhibitor clorgyline augmented the apoptotic responses induced by docetaxel. In summary, we determined that the expression of MAOA is induced by exposure to cytotoxic chemotherapy, increases HIF1α, and contributes to docetaxel resistance. As MAOA inhibitors have been approved for human use, regimens combining MAOA inhibitors with docetaxel may improve clinical outcomes.

Comparative toxicity of 20 herbicides to 5 periphytic algae and the relationship with mode of action.

PubMed

Nagai, Takashi; Taya, Kiyoshi; Yoda, Ikuko

2016-02-01

The authors used 5 species of periphytic algae to conduct toxicity assays of 20 herbicides. The 5 tested species represent riverine primary producers most likely to be affected by herbicides. A fluorescence microplate toxicity assay was used as an efficient and economical high-throughput assay. Toxicity characteristics were analyzed, focusing on their relationship to herbicide mode of action. The relative differences between 50% and 10% effect concentrations depended on herbicide mode of action, rather than tested species. Moreover, a clear relationship between sensitive species and herbicide mode of action was also observed. Green alga was most sensitive to herbicides of 2 mode of action groups: inhibitors of protoporphyrinogen oxidase and very long-chain fatty acid synthesis. Diatoms were most sensitive to herbicides of 1 mode of action group: 4-hydroxyphenyl-pyruvate-dioxygenase inhibitors. Cyanobacterium was most sensitive to herbicides of 1 mode of action group: inhibitors of acetolactate synthase. The species sensitivity distribution based on obtained data was also analyzed. The slopes of the species sensitivity distribution significantly differed among modes of action, suggesting that difference in species sensitivity is specific to the mode of action. In particular, differences in species sensitivity were markedly large for inhibitors of acetolactate synthase, protoporphyrinogen oxidase, and very long-chain fatty acid synthesis. The results clearly showed that a single algal species cannot represent the sensitivity of an algal assemblage. Therefore, multispecies algal toxicity data are essential for substances with specific modes of action. © 2015 SETAC.

Inhibitors of polyamine metabolism: review article.

PubMed

Wallace, H M; Fraser, A V

2004-07-01

The identification of increased polyamine concentrations in a variety of diseases from cancer and psoriasis to parasitic infections has led to the hypothesis that manipulation of polyamine metabolism is a realistic target for therapeutic or preventative intervention in the treatment of certain diseases. The early development of polyamine biosynthetic single enzyme inhibitors such as alpha-difluoromethylornithine (DFMO) and methylglyoxal bis(guanylhydrazone) showed some interesting early promise as anticancer drugs, but ultimately failed in vivo. Despite this, DFMO is currently in use as an effective anti-parasitic agent and has recently also been shown to have further potential as a chemopreventative agent in colorectal cancer. The initial promise in vitro led to the development and testing of other potential inhibitors of the pathway namely the polyamine analogues. The analogues have met with greater success than the single enzyme inhibitors possibly due to their multiple targets. These include down regulation of polyamine biosynthesis through inhibition of ornithine decarboxylase and S-adenosylmethionine decarboxylase and decreased polyamine uptake. This coupled with increased activity of the catabolic enzymes, polyamine oxidase and spermidine/spermine N1-acetyltransferase, and increased polyamine export has made the analogues more effective in depleting polyamine pools. Recently, the identification of a new oxidase (PAO-h1/SMO) in polyamine catabolism and evidence of induction of both PAO and PAO-h1/SMO in response to polyamine analogue treatment, suggests the analogues may become an important part of future chemotherapeutic and/or chemopreventative regimens.

Probing the ubiquinol-binding site of recombinant Sauromatum guttatum alternative oxidase expressed in E. coli membranes through site-directed mutagenesis.

PubMed

Young, Luke; May, Benjamin; Pendlebury-Watt, Alice; Shearman, Julia; Elliott, Catherine; Albury, Mary S; Shiba, Tomoo; Inaoka, Daniel Ken; Harada, Shigeharu; Kita, Kiyoshi; Moore, Anthony L

2014-07-01

In the present paper we have investigated the effect of mutagenesis of a number of highly conserved residues (R159, D163, L177 and L267) which we have recently shown to line the hydrophobic inhibitor/substrate cavity in the alternative oxidases (AOXs). Measurements of respiratory activity in rSgAOX expressed in Escherichia coli FN102 membranes indicate that all mutants result in a decrease in maximum activity of AOX and in some cases (D163 and L177) a decrease in the apparent Km (O2). Of particular importance was the finding that when the L177 and L267 residues, which appear to cause a bottleneck in the hydrophobic cavity, are mutated to alanine the sensitivity to AOX antagonists is reduced. When non-AOX anti-malarial inhibitors were also tested against these mutants widening the bottleneck through removal of isobutyl side chain allowed access of these bulkier inhibitors to the active-site and resulted in inhibition. Results are discussed in terms of how these mutations have altered the way in which the AOX's catalytic cycle is controlled and since maximum activity is decreased we predict that such mutations result in an increase in the steady state level of at least one O2-derived AOX intermediate. Such mutations should therefore prove to be useful in future stopped-flow and electron paramagnetic resonance experiments in attempts to understand the catalytic cycle of the alternative oxidase which may prove to be important in future rational drug design to treat diseases such as trypanosomiasis. Furthermore since single amino acid mutations in inhibitor/substrate pockets have been found to be the cause of multi-drug resistant strains of malaria, the decrease in sensitivity to main AOX antagonists observed in the L-mutants studied in this report suggests that an emergence of drug resistance to trypanosomiasis may also be possible. Therefore we suggest that the design of future AOX inhibitors should have structures that are less reliant on the orientation by the two-leucine residues. This article is part of a Special Issue entitled: 18th European Bioenergetic Conference. Copyright © 2014 Elsevier B.V. All rights reserved.

Development of 2-(Substituted Benzylamino)-4-Methyl-1, 3-Thiazole-5-Carboxylic Acid Derivatives as Xanthine Oxidase Inhibitors and Free Radical Scavengers.

PubMed

Ali, Md Rahmat; Kumar, Suresh; Afzal, Obaid; Shalmali, Nishtha; Sharma, Manju; Bawa, Sandhya

2016-04-01

A series of 2-(substituted benzylamino)-4-methylthiazole-5-carboxylic acid was designed and synthesized as structural analogue of febuxostat. A methylene amine spacer was incorporated between the phenyl ring and thiazole ring in contrast to febuxostat in which the phenyl ring was directly linked with the thiazole moiety. The purpose of incorporating methylene amine was to provide a heteroatom which is expected to favour hydrogen bonding within the active site residues of the enzyme xanthine oxidase. The structure of all the compounds was established by the combined use of FT-IR, NMR and MS spectral data. All the compounds were screened in vitro for their ability to inhibit the enzyme xanthine oxidase as per the reported procedure along with DPPH free radical scavenging assay. Compounds 5j, 5k and 5l demonstrated satisfactory potent xanthine oxidase inhibitory activities with IC50 values, 3.6, 8.1 and 9.9 μm, respectively, whereas compounds 5k, 5n and 5p demonstrated moderate antioxidant activities having IC50 15.3, 17.6 and 19.6 μm, respectively, along with xanthine oxidase inhibitory activity. Compound 5k showed moderate xanthine oxidase inhibitory activity as compared with febuxostat along with antioxidant activity. All the compounds were also studied for their binding affinity in active site of enzyme (PDB ID-1N5X). © 2015 John Wiley & Sons A/S.

Dual blockade of aldosterone and angiotensin II additively suppresses TGF-beta and NADPH oxidase in the hypertensive kidney.

PubMed

Onozato, Maristela Lika; Tojo, Akihiro; Kobayashi, Naohiko; Goto, Atsuo; Matsuoka, Hiroaki; Fujita, Toshiro

2007-05-01

Angiotensin II blockade and spironolactone effectively reduces proteinuria in humans. To clarify the mechanisms of the beneficial effect of blockade of both aldosterone and angiotensin II, we associated the aldosterone antagonist eplerenone to an angiotensin-converting enzyme inhibitor (ACEI) and examined the effect on renal transforming growth factor (TGF)-beta expression and oxidative stress by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in the Dahl salt-sensitive rat with heart failure (DSHF). Dahl salt-resistant control rats and DSHF rats were fed with 8% NaCl diet and at 11 weeks the DSHF rats were treated with vehicle, eplerenone (Epl), trandolapril or a combination of both drugs for 7 weeks. DSHF rats showed increased NADPH oxidase and decreased superoxide dismutase (SOD) resulting in increased oxidative stress. ACEI and Epl reduced NADPH oxidase showing an additive effect in their combination; ACEI increased manganese SOD (MnSOD) and Epl increased MnSOD, copper-zinc SOD and catalase, resulting in the lowest levels of oxidative stress with the combination therapy. Glomerulosclerosis and proteinuria were increased in the DSHF rats, and Epl suppressed them more effectively than ACEI to levels not different from the combination of both, showing a positive correlation with NADPH oxidase expression and TGF-beta. Renal TGF-beta was specifically suppressed with Epl The association of Epl to ACEI is beneficial due to further reduction of NADPH oxidase and specific inhibition of TGF-beta resulting in improvement of renal damage.

Multipotent cholinesterase/monoamine oxidase inhibitors for the treatment of Alzheimer's disease: design, synthesis, biochemical evaluation, ADMET, molecular modeling, and QSAR analysis of novel donepezil-pyridyl hybrids.

PubMed

Bautista-Aguilera, Oscar M; Esteban, Gerard; Chioua, Mourad; Nikolic, Katarina; Agbaba, Danica; Moraleda, Ignacio; Iriepa, Isabel; Soriano, Elena; Samadi, Abdelouahid; Unzeta, Mercedes; Marco-Contelles, José

2014-01-01

The design, synthesis, and biochemical evaluation of donepezil-pyridyl hybrids (DPHs) as multipotent cholinesterase (ChE) and monoamine oxidase (MAO) inhibitors for the potential treatment of Alzheimer's disease (AD) is reported. The 3D-quantitative structure-activity relationship study was used to define 3D-pharmacophores for inhibition of MAO A/B, acetylcholinesterase (AChE), and butyrylcholinesterase (BuChE) enzymes and to design DPHs as novel multi-target drug candidates with potential impact in the therapy of AD. DPH14 (Electrophorus electricus AChE [EeAChE]: half maximal inhibitory concentration [IC50] =1.1±0.3 nM; equine butyrylcholinesterase [eqBuChE]: IC50 =600±80 nM) was 318-fold more potent for the inhibition of AChE, and 1.3-fold less potent for the inhibition of BuChE than the reference compound ASS234. DPH14 is a potent human recombinant BuChE (hBuChE) inhibitor, in the same range as DPH12 or DPH16, but 13.1-fold less potent than DPH15 for the inhibition of human recombinant AChE (hAChE). Compared with donepezil, DPH14 is almost equipotent for the inhibition of hAChE, and 8.8-fold more potent for hBuChE. Concerning human monoamine oxidase (hMAO) A inhibition, only DPH9 and 5 proved active, compound DPH9 being the most potent (IC50 [MAO A] =5,700±2,100 nM). For hMAO B, only DPHs 13 and 14 were moderate inhibitors, and compound DPH14 was the most potent (IC50 [MAO B] =3,950±940 nM). Molecular modeling of inhibitor DPH14 within EeAChE showed a binding mode with an extended conformation, interacting simultaneously with both catalytic and peripheral sites of EeAChE thanks to a linker of appropriate length. Absortion, distribution, metabolism, excretion and toxicity analysis showed that structures lacking phenyl-substituent show better druglikeness profiles; in particular, DPHs13-15 showed the most suitable absortion, distribution, metabolism, excretion and toxicity properties. Novel donepezil-pyridyl hybrid DPH14 is a potent, moderately selective hAChE and selective irreversible hMAO B inhibitor which might be considered as a promising compound for further development for the treatment of AD.

Protection by mTOR Inhibition on Zymosan-Induced Systemic Inflammatory Response and Oxidative/Nitrosative Stress: Contribution of mTOR/MEK1/ERK1/2/IKKβ/IκB-α/NF-κB Signalling Pathway.

PubMed

Sahan-Firat, Seyhan; Temiz-Resitoglu, Meryem; Guden, Demet Sinem; Kucukkavruk, Sefika Pinar; Tunctan, Bahar; Sari, Ayse Nihal; Kocak, Zumrut; Malik, Kafait U

2018-02-01

Mammalian target of rapamycin (mTOR), a serine/threonine kinase regulate variety of cellular functions including cell growth, differentiation, cell survival, metabolism, and stress response, is now appreciated to be a central regulator of immune responses. Because mTOR inhibitors enhanced the anti-inflammatory activities of regulatory T cells and decreased the production of proinflammatory cytokines by macrophages, mTOR has been a pharmacological target for inflammatory diseases. In this study, we examined the role of mTOR in the production of proinflammatory and vasodilator mediators in zymosan-induced non-septic shock model in rats. To elucidate the mechanism by which mTOR contributes to non-septic shock, we have examined the activity of nicotinamide adenine dinucleotide phosphate (NADPH) oxidase system caused by mTOR/mitogen-activated protein kinase kinase (MEK1)/extracellular signal-regulated kinase (ERK1/2)/inhibitor κB kinase (IKKβ)/inhibitor of κB (IκB-α)/nuclear factor-κB (NF-κB) signalling pathway activation. After 1 h of zymosan (500 mg/kg, i.p.) administration to rats, mean arterial blood pressure (MAP) was decreased and heart rate (HR) was increased. These changes were associated with increased expression and/or activities of ribosomal protein S6, MEK1, ERK1/2, IKKβ, IκB-α and NF-κB p65, and NADPH oxidase system activity in cardiovascular and renal tissues. Rapamycin (1 mg/kg, i.p.), a selective mTOR inhibitor, reversed these zymosan-induced changes in these tissues. These observations suggest that activation of mTOR/MEK1/ERK1/2/IKKβ/IκB-α/NF-κB signalling pathway with proinflammatory and vasodilator mediator formation and NADPH oxidase system activity contributes to systemic inflammation in zymosan-induced non-septic shock. Thus, mTOR may be an optimal target for the treatment of the diseases characterized by the severe systemic inflammatory response.

NADPH oxidase 4-derived superoxide mediates flow-stimulated NKCC2 activity in thick ascending limbs.

PubMed

Saez, Fara; Hong, Nancy J; Garvin, Jeffrey L

2018-05-01

Luminal flow augments Na + reabsorption in the thick ascending limb more than can be explained by increased ion delivery. This segment reabsorbs 30% of the filtered load of Na + , playing a key role in its homeostasis. Whether flow elevations enhance Na + -K + -2Cl - cotransporter (NKCC2) activity and the second messenger involved are unknown. We hypothesized that raising luminal flow augments NKCC2 activity by enhancing superoxide ([Formula: see text]) production by NADPH oxidase 4 (NOX4). NKCC2 activity was measured in thick ascending limbs perfused at either 5 or 20 nl/min with and without inhibitors of [Formula: see text] production. Raising luminal flow from 5 to 20 nl/min enhanced NKCC2 activity from 4.8 ± 0.9 to 6.3 ± 1.2 arbitrary fluorescent units (AFU)/s. Maintaining flow at 5 nl/min did not alter NKCC2 activity. The superoxide dismutase mimetic manganese (III) tetrakis (4-benzoic acid) porphyrin chloride blunted NKCC2 activity from 3.5 ± 0.4 to 2.5 ± 0.2 AFU/s when flow was 20 nl/min but not 5 nl/min. When flow was 20 nl/min, NKCC2 activity showed no change with time. The selective NOX1/4 inhibitor GKT-137831 blunted NKCC2 activity when thick ascending limbs were perfused at 20 nl/min from 7.2 ± 1.1 to 4.5 ± 0.8 AFU/s but not at 5 nl/min. The inhibitor also prevented luminal flow from elevating [Formula: see text] production. Allopurinol, a xanthine oxidase inhibitor, had no effect on NKCC2 activity when flow was 20 nl/min. Tetanus toxin prevents flow-induced stimulation of NKCC2 activity. We conclude that elevations in luminal flow enhance NaCl reabsorption in thick ascending limbs by stimulating NKCC2 via NOX4 activation and increased [Formula: see text]. NKCC2 activation is primarily the result of insertion of new transporters in the membrane.

NADPH oxidase 4 is involved in the triethylene glycol dimethacrylate-induced reactive oxygen species and apoptosis in human embryonic palatal mesenchymal and dental pulp cells.

PubMed

Yeh, Cheng-Chang; Chang, Jenny Zwei-Chieng; Yang, Wan-Hsien; Chang, Hao-Hueng; Lai, Eddie Hsiang-Hua; Kuo, Mark Yen-Ping

2015-07-01

Triethylene glycol dimethacrylate (TEGDMA) is a common component of resin-based dental composites and endodontic sealers. TEGDMA induces apoptosis in several types of cells. However, the mechanisms are not completely understood. The aim of this study was to investigate the mechanisms underlying TEGDMA-induced apoptosis in human embryonic palatal mesenchymal (HEPM) pre-osteoblasts and primary human dental pulp (HDP) cells. Cell viability was examined after TEGDMA treatment. Cell cycle progression was checked by flow cytometry. Apoptotic cells were evaluated using terminal deoxynucleotidyl transferase (TdT)-mediated dUTP nick end labeling assay and visualized by fluorescence microscopy. Western blot analyses were performed to determine expressions of apoptosis-related proteins. The production of reactive oxygen species (ROS) was detected using flow cytometry. NADPH oxidase 4 (NOX4) expression levels were investigated using real-time quantitative polymerase chain reaction and Western blot analyses. TEGDMA increased cytosol cytochrome c levels and activated caspase-9 in HEPM and HDP cells. TEGDMA decreased the expression of anti-apoptotic protein Bcl-XL. TEGDMA-induced apoptosis was inhibited by caspase-9-specific inhibitor, anti-oxidants, NOX inhibitor, NOX4 inhibitor, and NOX4 small interfering RNA (siRNA). TEGDMA increased ROS production and upregulated NOX4 mRNA and protein expression. TEGDMA-induced intracellular ROS production was inhibited by NOX inhibitor and NOX4 inhibitor. We demonstrate significant involvement of NOX4 in the TEGDMA-induced ROS. NOX4-derived ROS subsequently induces mitochondrial cytochrome c release leading to apoptosis through activation of the intrinsic apoptotic pathway. NOX4 may be a potential target for strategies to prevent or ameliorate the TEGDMA-induced toxicity in HEPM and HDP cells.

Monoamine oxidase inhibitory activity of methoxy-substituted chalcones.

PubMed

Mathew, Bijo; Mathew, Githa Elizabeth; Ucar, Gulberk; Joy, Monu; Nafna, E K; Lohidakshan, Krishnakumar K; Suresh, Jerad

2017-11-01

The MAO-B inhibitory activity of chalcone (1, 3- diphenyl-2-propen-1-one) based compounds arise from its structural similarity with 1, 4-diphenyl-2-butene, a known MAO-B inhibitor. Based on our previous report, the methoxy-substituted with fluorine containing chalcones are promising reversible MAO-B inhibitors, while in the present study, a series of methoxylated chalcones (C1-C9) bearing substitution on the para position of ring B was synthesized and evaluated for their human monoamine oxidase inhibitory activity. With the exception of (2E)-1-(4-methoxyphenyl)-3-(4-nitrophenyl) prop-2-en-1-one (C7), which is a nonselective inhibitor, the chalcones exhibited competitive, selective, and reversible inhibition of hMAO-B. The most potent compound, (2E)-3-[4-(dimethylamino) phenyl]-1-(4-methoxyphenyl) prop-2-en-1-one (C5), showed the best inhibitory activity towards hMAO-B (IC 50 =0.29±0.011μM;K i =0.14±0.001μM). The reversibility of MAO-B inhibition by compound C5 was demonstrated by the recovery of enzyme activity after dialysis of mixtures containing enzyme and inhibitor. The reversiblity of C5 was 25.38±1.40 and 92.00±3.87% before and after dialysis, respectively. PAMPA was carried out to evaluate the blood-brain barrier effects of the designated compounds. Moreover, the most potent MAO-B inhibitor, C5, was found to be nontoxic towards cultured hepatic cells at 5 and 25μM, with 97 and 90% viability. Molecular docking study was performed against hMAO-B to observe the binding site interactions of the lead compound. Copyright © 2017 Elsevier B.V. All rights reserved.

Cytochrome P4502E1 primes macrophages to increase TNF-alpha production in response to lipopolysaccharide.

PubMed

Cao, Qi; Mak, Ki M; Lieber, Charles S

2005-07-01

Kupffer cells become activated in response to elevated levels of LPS during ethanol feeding, but the role of ethanol in the molecular processes of activation remains unclear. Because cytochrome P4502E1 (CYP2E1) is upregulated in Kupffer cells after ethanol, we hypothesized that this effect primes Kupffer cells, sensitizing them to increase TNF-alpha production in response to LPS. However, cultured Kupffer cells rapidly lose their CYP2E1. This difficulty was overcome by transfecting CYP2E1 to RAW 264.7 macrophages. Macrophages with stable increased CYP2E1 expression (E2) displayed increased levels of CD14/Toll-like receptor 4, NADPH oxidase and H2O2, accompanied by activation of ERK1/2, p38, and NF-kappaB. These increases primed E2 cells, sensitizing them to LPS stimuli, with amplification of LPS signaling, resulting in increased TNF-alpha production. Diphenyleneiodonium, a NADPH oxidase inhibitor, and diallyl sulfide, a CYP2E1 inhibitor, decreased approximately equally H2O2 levels in E2 cells, suggesting that NADPH oxidase and CYP2E1 contribute equally to H2O2 generation. Because CYP2E1 expression also enhanced the levels of the membrane localized NADPH oxidase subunits p47phox and p67phox, thereby contributing to the oxidase activation, it may augment H2O2 generation via this mechanism. H2O2, derived in part from NADPH and CYP2E1, activated ERK1/2 and p38. ERK1/2 stimulated TNF-alpha production via activation of NF-kappaB, whereas p38 promoted TNF-alpha production by stabilizing TNF-alpha mRNA. Oxidant generation after CYP2E1 overexpression appears to be central to macrophage priming and their sensitization to LPS. Accordingly, CYP2E1 priming could explain the sensitization of Kupffer cells to LPS activation by ethanol, a critical early step in alcoholic liver disease.

Design and synthesis of novel chalcones as potent selective monoamine oxidase-B inhibitors.

PubMed

Hammuda, Arwa; Shalaby, Raed; Rovida, Stefano; Edmondson, Dale E; Binda, Claudia; Khalil, Ashraf

2016-05-23

A novel series of substituted chalcones were designed and synthesized to be evaluated as selective human MAO-B inhibitors. A combination of either methylsulfonyl or trifluoromethyl substituents on the aromatic ketone moiety with a benzodioxol ring on the other end of the chalcone scaffold was investigated. The compounds were tested for their inhibitory activities on both human MAO-A and B. All compounds appeared to be selective MAO-B inhibitors with Ki values in the micromolar to submicromolar range. Molecular modeling studies have been performed to get insight into the binding mode of the synthesized compounds to human MAO-B active site. Copyright © 2016 Elsevier Masson SAS. All rights reserved.

▼ Safinamide for Parkinson's disease.

PubMed

2018-05-01

▼ Safinamide (Xadago - Zambon S.p.A) is a monoamine-oxidase B (MAO-B) inhibitor licensed as add-on therapy for people with idiopathic Parkinson's disease who are experiencing motor fluctuations with levodopa. 1 Currently there is no cure for Parkinson's disease and drugs are used to reduce motor symptoms and improve daily activities. 2,3 Here, we review the evidence for this MAO-B inhibitor. Published by the BMJ Publishing Group Limited. For permission to use (where not already granted under a licence) please go to http://www.bmj.com/company/products-services/rights-and-licensing/.

Hypouricaemic action of mangiferin results from metabolite norathyriol via inhibiting xanthine oxidase activity.

PubMed

Niu, Yanfen; Liu, Jia; Liu, Hai-Yang; Gao, Li-Hui; Feng, Guo-Hua; Liu, Xu; Li, Ling

2016-09-01

Context Mangiferin has been reported to possess a potential hypouricaemic effect. However, the pharmacokinetic studies in rats showed that its oral bioavailability was only 1.2%, suggesting that mangiferin metabolites might exert the action. Objective The hypouricaemic effect and the xanthine oxidase inhibition of mangiferin and norathyriol, a mangiferin metabolite, were investigated. Inhibition of norathyriol analogues (compounds 3-9) toward xanthine oxidase was also evaluated. Materials and methods For a dose-dependent study, mangiferin (1.5-6.0 mg/kg) and norathyriol (0.92-3.7 mg/kg) were administered intragastrically to mice twice daily for five times. For a time-course study, mice received mangiferin and norathyriol both at a single dose of 7.1 μmol/kg. In vitro, inhibition of test compounds (2.4-2.4 mM) against xanthine oxidase activity was evaluated by the spectrophotometrical method. The inhibition type was identified from Lineweaver-Burk plots. Results Norathyriol (0.92, 1.85 and 3.7 mg/kg) dose dependently decreased the serum urate levels by 27.0, 33.6 and 37.4%, respectively. The action was more potent than that of mangiferin at the low dose, but was equivalent at the higher doses. Additionally, the hypouricaemic action of them exhibited a time dependence. In vitro, norathyriol markedly inhibited the xanthine oxidase activities, with the IC50 value of 44.6 μM, but mangiferin did not. The kinetic studies showed that norathyriol was an uncompetitive inhibitor by Lineweaver-Burk plots. The structure-activity relationships exhibited that three hydroxyl groups in norathyriol at the C-1, C-3 and C-6 positions were essential for maintaining xanthine oxidase inhibition. Discussion and conclusion Norathyriol was responsible for the hypouricaemic effect of mangiferin via inhibiting xanthine oxidase activity.

P2x7 Receptor-NADPH Oxidase-Axis Mediates Protein radical Formation And Kupffer Cell Activation in Carbon Tetrachloride-Mediated Steatohepatitis in Obese Mice

PubMed Central

Chatterjee, Saurabh; Rana, Ritu; Corbett, Jean; Kadiiska, Maria B.; Goldstein, Joyce; Mason, Ronald P.

2012-01-01

While some studies show that carbon tetrachloride-mediated metabolic oxidative stress exacerbates steatohepatitic-like lesions in obese mice, the redox mechanisms that trigger the innate immune system and accentuate the inflammatory cascade remain unclear. Here we have explored the role of the purinergic receptor P2X7-NADPH oxidase axis as a primary event in recognizing the heightened release of extracellular ATP from CCl4-treated hepatocytes and generating redoxmediated Kupffer cell activation in obese mice. We found that an underlying condition of obesity led to the formation of protein radicals and post-translational nitration, primarily in Kupffer cells, at 24 h post-CCl4 administration. The free radical-mediated oxidation of cellular macromolecules, which was NADPH oxidase- and P2X7 receptor-dependent, correlated well with the release of TNF- α and MCP-2 from Kupffer cells. The Kupffer cells in CCl4-treated mice exhibited increased expression of MHC Class II proteins and showed an activated phenotype. Increased expression of MHC Class II was inhibited by the NADPH oxidase inhibitor apocynin , P2X7 receptor antagonist A438709 hydrochloride, and genetic deletions of the NADPH oxidase p47 phox subunit or the P2X7 receptor. The P2X7 receptor acted upstream of NADPH oxidase activation by up-regulating the expression of the p47 phox subunit and p47 phox binding to the membrane subunit, gp91 phox. We conclude that the P2X7 receptor is a primary mediator of oxidative stress-induced exacerbation of inflammatory liver injury in obese mice via NADPH oxidase-dependent mechanisms. PMID:22343416

Effects of NADPH oxidase inhibitor on diabetic nephropathy in OLETF rats: the role of reducing oxidative stress in its protective property.

PubMed

Nam, Soo Min; Lee, Mi Young; Koh, Jang Hyun; Park, Jun Ho; Shin, Jang Yel; Shin, Young Goo; Koh, Sang Baek; Lee, Eun Young; Chung, Choon Hee

2009-02-01

Diabetic nephropathy is the most serious complication in diabetes mellitus. Oxidative stress via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and vascular endothelial growth factor (VEGF) pathway play critical roles in the development of diabetic nephropathy. We evaluated the effects of apocynin, NADPH oxidase inhibitor on diabetic nephropathy in a type 2 diabetic rat model. Sixteen Otsuka Long Evans Tokushima Fatty (OLETF) rats and 9 Long Evans Tokushima Otsuka (LETO) were divided into the following three groups: LETO rats (n=9), control OLETF rats (n=7) and apocynin-treated OLETF rats (n=9). We examined body weights, plasma glucose levels, urinary albumin-creatinine ratio (ACR) and protein-creatinine ratio (PCR). At 50 weeks, experimental rats were sacrificed and their kidneys were extracted for hematoxylin eosin stain, immunohistochemical VEGF stain and VEGF mRNA real-time RT-PCR. To examine oxidative stress, we checked 24h urinary 8-OHdG (8-hydroxy-2'-deoxyguanosine) and MDA (malondialdehyde). Urinary protein and albumin excretions were reduced after apocynin treatment, though apocynin could not significantly decrease serum glucose levels. There were improvements of glomerular and mesangial expansion in the apocynin-treated OLETF rats. Apocynin significantly decreased optical density of glomerular VEGF expression in immunohistochemical stain and reduced the concentration of 24h urinary 8-OHdG and MDA. From these results, it was suggested that apocynin may have the potential to protect against diabetic nephropathy via amelioration of oxidative stress.

Tyramine-induced noradrenaline release from rat brain slices: prevention by (-)-deprenyl.

PubMed Central

Glover, V.; Pycock, C. J.; Sandler, M.

1983-01-01

Clorgyline (1 and 10 microM) and (+)-deprenyl (10 microM) both significantly potentiated the tyramine (100 microM)-induced release of [3H]-noradrenaline from rat cerebral cortex slices. (-)-Deprenyl (50 microM) significantly reduced it, while lower concentrations had no effect on noradrenaline release. However, in combination, 1 microM (-)-deprenyl blocked the release-facilitating action of 1 microM clorgyline, and 10 microM (-)-deprenyl that of 10 microM (+)-deprenyl. Low concentrations of (+)- and (-)-deprenyl (1 and 10 microM), both selectively inhibited phenylethylamine oxidation by monoamine oxidase B. Higher concentrations of (-)-deprenyl (20 and 50 microM) also inhibited 5-hydroxytryptamine oxidation by monoamine oxidase A. Clorgyline (1 and 10 microM) inhibited both enzymes. Thus, the effects of these drugs on noradrenaline-release cannot be explained solely in terms of irreversible inhibition of monoamine oxidase A and B, and other possible mechanisms are discussed. If the brain-slice model faithfully mirrors the sequence of events manifesting peripherally as the tyramine hypertensive response ('cheese effect'), then it is possible that low doses of (-)-deprenyl, administered with antidepressant monoamine oxidase inhibitors, can prevent this adverse reaction. PMID:6418254

Identification of a Catalase-Phenol Oxidase in Betalain Biosynthesis in Red Amaranth (Amaranthus cruentus)

PubMed Central

Teng, Xiao-Lu; Chen, Ning; Xiao, Xing-Guo

2016-01-01

Betalains are a group of nitrogen-containing pigments that color plants in most families of Caryophyllales. Their biosynthesis has long been proposed to begin with hydroxylation of L-tyrosine to L-DOPA through monophenolase activity of tyrosinase, but biochemical evidence in vivo remains lacking. Here we report that a Group 4 catalase, catalase-phenol oxidase (named as AcCATPO), was identified, purified and characterized from leaves of Amaranthus cruentus, a betalain plant. The purified enzyme appeared to be a homotrimeric protein composed of subunits of about 58 kDa, and demonstrated not only the catalase activity toward H2O2, but also the monophenolase activity toward L-tyrosine and diphenolase activity toward L-DOPA. Its catalase and phenol oxidase activities were inhibited by common classic catalase and tyrosinase inhibitors, respectively. All its peptide fragments identified by nano-LC-MS/MS were targeted to catalases, and matched with a cDNA-encoded polypeptide which contains both classic catalase and phenol oxidase active sites. These sites were also present in catalases of non-betalain plants analyzed. AcCATPO transcript abundance was positively correlated with the ratio of betaxanthin to betacyanin in both green and red leaf sectors of A. tricolor. These data shows that the fourth group catalase, catalase-phenol oxidase, is present in plant, and might be involved in betaxanthin biosynthesis. PMID:26779247

A benzoxazine derivative induces vascular endothelial cell apoptosis in the presence of fibroblast growth factor-2 by elevating NADPH oxidase activity and reactive oxygen species levels.

PubMed

Zhao, Jing; He, Qiuxia; Cheng, Yizhe; Zhao, Baoxiang; Zhang, Yun; Zhang, Shangli; Miao, Junying

2009-09-01

Previously, we found that 6,8-dichloro-2,3-dihydro-3-hydroxymethyl-1,4-benzoxazine (DBO) promoted apoptosis of human umbilical vascular endothelial cells (HUVECs) deprived of growth factors. In this study, we aimed to investigate the effect of DBO and its mechanism of action on angiogenesis and apoptosis of HUVECs in the presence of fibroblast growth factor-2 (FGF-2), which promotes angiogenesis and inhibits apoptosis in vivo and in vitro. DBO significantly inhibited capillary-like tube formation by promoting apoptosis of HUVECs in the presence of FGF-2 in vitro. Furthermore, DBO elevated the levels of reactive oxygen species (ROS) and nitric oxide (NO) and increased the activity of NADPH oxidase and inducible nitric oxide synthase (iNOS) in promoting apoptosis under this condition. Moreover, when NADPH oxidase was inhibited by its specific inhibitor, dibenziodolium chloride (DPI), DBO could not elevate ROS and NO levels in HUVECs. The data suggest that DBO is a new modulator of apoptosis in vitro, and it might function by increasing the activity of NADPH oxidase and iNOS, subsequently elevating the levels of ROS and NO in HUVECs. The findings of this study provide a new small molecule for investigating the FGF-2/NADPH oxidase/iNOS signaling pathway in apoptosis.

Spermine oxidase promotes bile canalicular lumen formation through acrolein production.

PubMed

Uemura, Takeshi; Takasaka, Tomokazu; Igarashi, Kazuei; Ikegaya, Hiroshi

2017-11-01

Spermine oxidase (SMOX) catalyzes oxidation of spermine to generate spermidine, hydrogen peroxide (H 2 O 2 ) and 3-aminopropanal, which is spontaneously converted to acrolein. SMOX is induced by a variety of stimuli including bacterial infection, polyamine analogues and acetaldehyde exposure. However, the physiological functions of SMOX are not yet fully understood. We investigated the physiological role of SMOX in liver cells using human hepatocellular carcinoma cell line HepG2. SMOX localized to the bile canalicular lumen, as determined by F-actin staining. Knockdown of SMOX reduced the formation of bile canalicular lumen. We also found that phospho-Akt (phosphorylated protein kinase B) was localized to canalicular lumen. Treatment with Akt inhibitor significantly reduced the formation of bile canalicular lumen. Acrolein scavenger also inhibited the formation of bile canalicular lumen. PTEN, phosphatase and tensin homolog and an inhibitor of Akt, was alkylated in a SMOX-dependent manner. Our results suggest that SMOX plays a central role in the formation of bile canalicular lumen in liver cells by activating Akt pathway through acrolein production.

New pyrrole inhibitors of monoamine oxidase: synthesis, biological evaluation, and structural determinants of MAO-A and MAO-B selectivity.

PubMed

La Regina, Giuseppe; Silvestri, Romano; Artico, Marino; Lavecchia, Antonio; Novellino, Ettore; Befani, Olivia; Turini, Paola; Agostinelli, Enzo

2007-03-08

A series of new pyrrole derivatives have been synthesized and evaluated for their monoamine oxidase (MAO) A and B inhibitory activity and selectivity. N-Methyl,N-(benzyl),N-(pyrrol-2-ylmethyl)amine (7) and N-(2-benzyl),N-(1-methylpyrrol-2-ylmethyl)amine (18) were the most selective MAO-B (7, SI = 0.0057) and MAO-A (18, SI = 12500) inhibitors, respectively. Docking and molecular dynamics simulations gave structural insights into the MAO-A and MAO-B selectivity. Compound 18 forms an H-bond with Gln215 through its protonated amino group into the MAO-A binding site. This H-bond is absent in the 7/MAO-A complex. In contrast, compound 7 places its phenyl ring into an aromatic cage of the MAO-B binding pocket, where it forms charge-transfer interactions. The slightly different binding pose of 18 into the MAO-B active site seems to be forced by a bulkier Tyr residue, which replaces a smaller Ile residue present in MAO-A.

A Small Molecule Polyamine Oxidase Inhibitor Blocks Androgen-Induced Oxidative Stress and Delays Prostate Cancer Progression in the TRAMP Mouse Model

PubMed Central

Basu, Hirak S.; Thompson, Todd A.; Church, Dawn R.; Clower, Cynthia C.; Mehraein-Ghomi, Farideh; Amlong, Corey A.; Martin, Christopher T.; Woster, Patrick M.; Lindstrom, Mary J.; Wilding, George

2009-01-01

High levels of reactive oxygen species (ROS) present in human prostate epithelia are an important etiological factor in prostate cancer (CaP) occurrence, recurrence and progression. Androgen induces ROS production in the prostate by a yet unknown mechanism. Here, to the best of our knowledge, we report for the first time that androgen induces an overexpression of spermidine/spermine N1-acetyltransferase (SSAT), the rate-limiting enzyme in the polyamine oxidation pathway. As prostatic epithelia produce a large excess of polyamines, the androgen-induced polyamine oxidation that produces H2O2 could be a major reason for the high ROS levels in the prostate epithelia. A small molecule polyamine oxidase inhibitor N,N'-butanedienyl butanediamine (MDL 72,527 or CPC-200) effectively blocks androgen-induced ROS production in human CaP cells as well as significantly delays CaP progression and death in animals developing spontaneous CaP. These data demonstrate that polyamine oxidation is not only a major pathway for ROS production in prostate, but inhibiting this pathway also successfully delays prostate cancer progression. PMID:19773450

Enzymes and Inhibitors in Neonicotinoid Insecticide Metabolism

PubMed Central

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

2009-01-01

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

Characterization of polyphenol oxidase from blueberry (Vaccinium corymbosum L.).

PubMed

Siddiq, M; Dolan, K D

2017-03-01

Polyphenol oxidase (PPO) was extracted and characterized from high-bush blueberries. PPO showed an optimum activity at pH 6.1-6.3 and 35°C, with the enzyme showing significant activity over a wide temperature range (25-60°C). Catechol was the most readily oxidized substrate followed by 4-methylcatechol, DL-DOPA, and dopamine. Blueberry PPO showed a K m of 15mM and V max of 2.57 ΔA 420 nm/min×10 -1 , determined with catechol. PPO was completely inactivated in 20min at 85°C, however, after 30minat 75°C it showed about 10% residual activity. Thermal treatment at 55 and 65°C for 30min resulted in the partial inactivation of PPO. Ascorbic acid, sodium diethyldithiocarbamic acid, L-cysteine, and sodium metabisulfite were effective inhibitors of PPO at 1.0mM. Benzoic acid and cinnamic acid series inhibitors showed relatively weak inhibition of PPO (21.8-27.6%), even at as high as 2.0mM concentration. Copyright © 2016 Elsevier Ltd. All rights reserved.

Febuxostat for the treatment of gout.

PubMed

Bridgeman, Mary Barna; Chavez, Benjamin

2015-02-01

Gout is a rheumatologic condition associated with elevated serum uric acid levels and deposition of monosodium urate crystals in joints and soft tissues. The xanthine oxidase inhibitor, allopurinol, has historically been the principle agent utilized for reducing elevated uric acid levels and treating underlying cause of gout symptoms; the availability of febuxostat, a newer non-purine selective xanthine oxidase inhibitor, represents an alternative therapy for those patients with contraindications or intolerance to allopurinol. This article reviews the published literature on the pharmacologic characteristics and clinical safety and efficacy data on the use of febuxostat in the treatment of gout. A literature search of MEDLINE and MEDLINE In-Process & Other Non-Indexed Citations Databases (1996-November 2014) was conducted utilizing the key words 'febuxostat', 'allopurinol', and 'gout'. All published articles regarding febuxostat were evaluated. References of selected articles, data from poster presentations, and abstract publications were additionally reviewed. Febuxostat has shown benefit with respect to symptomatic relief and uric acid level reduction. The safety profile of this agent makes it an ideal alternative in those patients with contraindications to or who are intolerant of allopurinol.

The protective role of Bax Inhibitor-1 against chronic mild stress through the inhibition of monoamine oxidase A

PubMed Central

Lee, Hwa-Young; Lee, Geum-Hwa; Marahatta, Anu; Lin, Shun-Mei; Lee, Mi-Rin; Jang, Kyu Yun; Kim, Kyung Min; Lee, Hee Jae; Lee, Jae-Won; Bagalkot, Tarique Rajasaheb; Chung, Young-Chul; Lee, Yong-Chul; Kim, Hyung-Ryong; Chae, Han-Jung

2013-01-01

The anti-apoptotic protein Bax inhibitor-1 (BI-1) is a regulator of apoptosis linked to endoplasmic reticulum (ER) stress. It has been hypothesized that BI-1 protects against neuron degenerative diseases. In this study, BI-1−/− mice showed increased vulnerability to chronic mild stress accompanied by alterations in the size and morphology of the hippocampi, enhanced ROS accumulation and an ER stress response compared with BI-1+/+ mice. BI-1−/− mice exposed to chronic mild stress showed significant activation of monoamine oxidase A (MAO-A), but not MAO-B, compared with BI-1+/+ mice. To examine the involvement of BI-1 in the Ca2+-sensitive MAO activity, thapsigargin-induced Ca2+ release and MAO activity were analyzed in neuronal cells overexpressing BI-1. The in vitro study showed that BI-1 regulates Ca2+ release and related MAO-A activity. This study indicates an endogenous protective role of BI-1 under conditions of chronic mild stress that is primarily mediated through Ca2+-associated MAO-A regulation. PMID:24292328

Mechanism of action and interactions between xanthine oxidase inhibitors derived from natural sources of chlorogenic and ferulic acids.

PubMed

Gawlik-Dziki, Urszula; Dziki, Dariusz; Świeca, Michał; Nowak, Renata

2017-06-15

The aim of this study was to estimate the phenolic composition and xanthine oxidase (XO) inhibitory activity of green coffee beans (GCB) and wholemeal wheat flour (WF). Additionally, the type and strength of interaction (expressed as the combination index, CI) and mode of XO inhibition were analyzed. The major phenolic in GCB was 5-caffeoylquinic acid (39.92mg/g dw). The main phenolic acids in WF were trans- and cis-ferulic acids (257 and 165.57mg/100g dw, respectively). Both ferulic and chlorogenic acids individually inhibited XO, and for their combination moderate synergism was found. Buffer extractable compounds from GCB and WF demonstrated slight synergism (CI=0.92), while potentially bioaccessible and bioavailable compounds acted synergistically (CI=0.43 and 0.54, respectively). Buffer-extractable and potentially bioavailable phytochemicals from GCB acted uncompetitively, whereas potentially bioaccessible compounds acted as noncompetitive XO inhibitors. The addition of 3-5% of GCB to wheat bread significantly increased XO-inhibitory activity. Copyright © 2017 Elsevier Ltd. All rights reserved.

Absence of diamine oxidase activity from rabbit and rat lungs.

PubMed Central

Rao, S B; Rao, K S; Mehendale, H M

1986-01-01

To study the presence of diamine oxidase (DAO) activity in any tissue with putrescine as the substrate, it is necessary to use inhibitors to block all pathways that could further metabolize gamma-aminobutyraldehyde, which is the product of enzyme reaction. It is also necessary to inhibit any enzyme that may convert putrescine into higher polyamines. By this approach it was observed that lung tissue of both rat and rabbit exhibited no DAO activity. DAO activity was observed in the rat and rabbit intestine, the former showing 3 times as much activity as the latter. The other potential pathways of putrescine metabolism are of no consequence in the rat and rabbit intestine and lungs. PMID:3087348

The reaction pathway of membrane-bound rat liver mitochondrial monoamine oxidase

PubMed Central

Houslay, Miles D.; Tipton, Keith F.

1973-01-01

1. A preparation of a partly purified mitochondrial outer-membrane fraction suitable for kinetic investigations of monoamine oxidase is described. 2. An apparatus suitable for varying the O2 concentration in a spectrophotometer cuvette is described. 3. The reaction catalysed by the membrane-bound enzyme is shown to proceed by a double-displacement (Ping Pong) mechanism, and a formal mechanism is proposed. 4. KCN, NaN3, benzyl cyanide and 4-cyanophenol are shown to be reversible inhibitors of the enzyme. 5. The non-linear reciprocal plot obtained with impure preparations of benzylamine, which is typical of high substrate inhibition, is shown to be due to aldehyde contamination of the substrate. PMID:4778271

Development of a method to screen and isolate potential xanthine oxidase inhibitors from Panax japlcus var via ultrafiltration liquid chromatography combined with counter-current chromatography.

PubMed

Li, Sainan; Tang, Ying; Liu, Chunming; Li, Jing; Guo, Liping; Zhang, Yuchi

2015-03-01

Panax japlcus var is a typical Chinese herb with a large number of saponins existing in all parts of it. The common methods of screening and isolating saponins are mostly labor-intensive and time-consuming. In this study, a new assay based on ultrafiltration-liquid chromatography-mass spectrometry (UF-LC-MS) was developed for the rapid screening and identifying of the ligands for xanthine oxidase from the extract of P. japlcus. Six saponins were identified as xanthine oxidase inhibitors from the extract. Subsequently, the specific binding ligands, namely, 24 (R)-majoroside R1, chikusetsusaponin IVa, oleanolic acid-28-O-β-D-glucopyranoside, notoginsenoside Fe, ginsenoside Rb2 and ginsenoside Rd (the purities of them were 95.74%, 96.12%, 93.19%, 94.83%, 95.07% and 94.62%, respectively) were separated by high-speed counter-current chromatography (HSCCC). The component ratio of the solvent system of HSCCC was calculated with the help of a multiexponential function model was optimized. The partition coefficient (K) values of the target compounds and resolutions of peaks were employed as the research indicators, and exponential function and binomial formulas were used to optimize the solvent system and flow rate of the mobile phases in a two-stage separation. An optimized two-phase solvent system composed of ethyl acetate, isopropanol, 0.1% aqueous formic acid (1.9:1.0:1.3, v/v/v, for the first-stage) and that composed of methylene chloride, acetonitrile, isopropanol, 0.1% aqueous formic acid (5.6:1.0:2.4:5.2, v/v/v/v, for the second-stage) were used to isolate the six compounds from P. japlcus. The targeted compounds isolated, collected and purified by HSCCC were analyzed by high performance liquid chromatography (UPLC), and the chemical structures of all the six compounds were identified by UV, MS and NMR. The results demonstrate that UF-LC-MS combined with HSCCC might provide not only a powerful tool for screening and isolating xanthine oxidase inhibitors in complex samples but also a useful platform for discovering bioactive compounds for the prevention and treatment of gout. Copyright © 2014 Elsevier B.V. All rights reserved.

Inducible bilirubin oxidase: A novel function for the mouse cytochrome P450 2A5

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

Abu-Bakar, A'edah, E-mail: a.abubakar@uq.edu.au; Arthur, Dionne Maioha; Cooperative Research Centre for Contamination Assessment and Remediation of the Environment, Adelaide

2011-11-15

We have previously shown that bilirubin (BR), a breakdown product of haem, is a strong inhibitor and a high affinity substrate of the mouse cytochrome P450 2A5 (CYP2A5). The antioxidant BR, which is cytotoxic at high concentrations, is potentially useful in cellular protection against oxygen radicals if its intracellular levels can be strictly controlled. The mechanisms that regulate cellular BR levels are still obscure. In this paper we provide preliminary evidence for a novel function of CYP2A5 as hepatic 'BR oxidase'. A high-performance liquid chromatography/electrospray ionisation mass spectrometry screening showed that recombinant yeast microsomes expressing the CYP2A5 oxidise BR tomore » biliverdin, as the main metabolite, and to three other smaller products with m/z values of 301, 315 and 333. The metabolic profile is significantly different from that of chemical oxidation of BR. In chemical oxidation the smaller products were the main metabolites. This suggests that the enzymatic reaction is selective, towards biliverdin production. Bilirubin treatment of primary hepatocytes increased the CYP2A5 protein and activity levels with no effect on the corresponding mRNA. Co-treatment with cycloheximide (CHX), a protein synthesis inhibitor, resulted in increased half-life of the CYP2A5 compared to cells treated only with CHX. Collectively, the observations suggest that the CYP2A5 is potentially an inducible 'BR oxidase' where BR may accelerate its own metabolism through stabilization of the CYP2A5 protein. It is possible that this metabolic pathway is potentially part of the machinery controlling intracellular BR levels in transient oxidative stress situations, in which high amounts of BR are produced. -- Highlights: Black-Right-Pointing-Pointer CYP2A5 metabolizes bilirubin to biliverdin and dipyrroles. Black-Right-Pointing-Pointer Bilirubin increased the hepatic CYP2A5 protein and activity levels. Black-Right-Pointing-Pointer Bilirubin does not change the hepatic CYP2A5 mRNA levels. Black-Right-Pointing-Pointer Co-treatment with a protein synthesis inhibitor prolongs CYP2A5 half-life. Black-Right-Pointing-Pointer CYP2A5 is potentially an inducible bilirubin oxidase.« less

The monoamine oxidase inhibition properties of selected structural analogues of methylene blue

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

Delport, Anzelle

The thionine dye, methylene blue (MB), is a potent inhibitor of monoamine oxidase (MAO) A, a property that may, at least in part, mediate its antidepressant effects in humans and animals. The central inhibition of MAO-A by MB has also been linked to serotonin toxicity (ST) which may arise when MB is used in combination with serotonergic drugs. Structural analogues and the principal metabolite of MB, azure B, have also been reported to inhibit the MAO enzymes, with all compounds exhibiting specificity for the MAO-A isoform. To expand on the structure-activity relationships (SARs) of MAO inhibition by MB analogues, themore » present study investigates the human MAO inhibition properties of five MB analogues: neutral red, Nile blue, new methylene blue, cresyl violet and 1,9-dimethyl methylene blue. Similar to MB, these analogues also are specific MAO-A inhibitors with cresyl violet (IC{sub 50} = 0.0037 μM), Nile blue (IC{sub 50} = 0.0077 μM) and 1,9-dimethyl methylene blue (IC{sub 50} = 0.018 μM) exhibiting higher potency inhibition compared to MB (IC{sub 50} = 0.07 μM). Nile blue also represents a potent MAO-B inhibitor with an IC{sub 50} value of 0.012 μM. From the results it may be concluded that non-thionine MB analogues (e.g. cresyl violet and Nile blue) also may exhibit potent MAO inhibition, a property which should be considered when using these compounds in pharmacological studies. Benzophenoxazines such as cresyl violet and Nile blue are, similar to phenothiazines (e.g. MB), representative of high potency MAO-A inhibitors with a potential risk of ST. - Highlights: • MB analogues, cresyl violet and Nile blue, are high potency MAO-A inhibitors. • Nile blue also represents a potent MAO-B inhibitor. • Potent MAO-A inhibition should alert to potential serotonin toxicity.« less

Molecular insights into human monoamine oxidase (MAO) inhibition by 1,4-naphthoquinone: evidences for menadione (vitamin K3) acting as a competitive and reversible inhibitor of MAO.

PubMed

Coelho Cerqueira, Eduardo; Netz, Paulo Augusto; Diniz, Cristiane; Petry do Canto, Vanessa; Follmer, Cristian

2011-12-15

Monoamine oxidase (MAO) catalyzes the oxidative deamination of biogenic and exogenous amines and its inhibitors have therapeutic value for several conditions including affective disorders, stroke, neurodegenerative diseases and aging. The discovery of 2,3,6-trimethyl-1,4-naphthoquinone (TMN) as a nonselective and reversible inhibitor of MAO, has suggested 1,4-naphthoquinone (1,4-NQ) as a potential scaffold for designing new MAO inhibitors. Combining molecular modeling tools and biochemical assays we evaluate the kinetic and molecular details of the inhibition of human MAO by 1,4-NQ, comparing it with TMN and menadione. Menadione (2-methyl-1,4-naphthoquinone) is a multitarget drug that acts as a precursor of vitamin K and an inducer of mitochondrial permeability transition. Herein we show that MAO-B was inhibited competitively by 1,4-NQ (K(i)=1.4 μM) whereas MAO-A was inhibited by non-competitive mechanism (K(i)=7.7 μM). Contrasting with TMN and 1,4-NQ, menadione exhibited a 60-fold selectivity for MAO-B (K(i)=0.4 μM) in comparison with MAO-A (K(i)=26 μM), which makes it as selective as rasagiline. Fluorescence and molecular modeling data indicated that these inhibitors interact with the flavin moiety at the active site of the enzyme. Additionally, docking studies suggest the phenyl side groups of Tyr407 and Tyr444 (for MAO-A) or Tyr398 and Tyr435 (for MAO-B) play an important role in the interaction of the enzyme with 1,4-NQ scaffold through forces of dispersion as verified for menadione, TMN and 1,4-NQ. Taken together, our findings reveal the molecular details of MAO inhibition by 1,4-NQ scaffold and show for the first time that menadione acts as a competitive and reversible inhibitor of human MAO. Copyright © 2011 Elsevier Ltd. All rights reserved.

Hyperglycaemia promotes human brain microvascular endothelial cell apoptosis via induction of protein kinase C-ßI and prooxidant enzyme NADPH oxidase.

PubMed

Shao, Beili; Bayraktutan, Ulvi

2014-01-01

Blood-brain barrier disruption represents a key feature in hyperglycaemia-aggravated cerebral damage after an ischaemic stroke. Although the underlying mechanisms remain largely unknown, activation of protein kinase C (PKC) is thought to play a critical role. This study examined whether apoptosis of human brain microvascular endothelial cells (HBMEC) might contribute to hyperglycaemia-evoked barrier damage and assessed the specific role of PKC in this phenomenon. Treatments with hyperglycaemia (25 mM) or phorbol myristate acetate (PMA, a protein kinase C activator, 100 nM) significantly increased NADPH oxidase activity, O2 (•-) generation, proapoptotic protein Bax expression, TUNEL-positive staining and caspase-3/7 activities. Pharmacological inhibition of NADPH oxidase, PKC-a, PKC-ß or PKC-ßI via their specific inhibitors and neutralisation of O2 (•-) by a cell-permeable superoxide dismutase mimetic, MnTBAP normalised all the aforementioned increases induced by hyperglycaemia. Suppression of these PKC isoforms also negated the stimulatory effects of hyperglycaemia on the protein expression of NADPH oxidase membrane-bound components, Nox2 and p22-phox which determine the overall enzymatic activity. Silencing of PKC-ßI gene through use of specific siRNAs abolished the effects of both hyperglycaemia and PMA on endothelial cell NADPH oxidase activity, O2 (•-) production and apoptosis and consequently improved the integrity and function of an in vitro model of human cerebral barrier comprising HBMEC, astrocytes and pericytes. Hyperglycaemia-mediated apoptosis of HBMEC contributes to cerebral barrier dysfunction and is modulated by sequential activations of PKC-ßI and NADPH oxidase.

Seasonal superoxide overproduction and endothelial activation in guinea-pig heart; seasonal oxidative stress in rats and humans.

PubMed

Konior, Anna; Klemenska, Emilia; Brudek, Magdalena; Podolecka, Ewa; Czarnowska, Elżbieta; Beręsewicz, Andrzej

2011-04-01

Seasonality in endothelial dysfunction and oxidative stress was noted in humans and rats, suggesting it is a common phenomenon of a potential clinical relevance. We aimed at studying (i) seasonal variations in cardiac superoxide (O(2)(-)) production in rodents and in 8-isoprostane urinary excretion in humans, (ii) the mechanism of cardiac O(2)(-) overproduction occurring in late spring/summer months in rodents, (iii) whether this seasonal O(2)(-)-overproduction is associated with a pro-inflammatory endothelial activation, and (iv) how the summer-associated changes compare to those caused by diabetes, a classical cardiovascular risk factor. Langendorff-perfused guinea-pig and rat hearts generated ~100% more O(2)(-), and human subjects excreted 65% more 8-isoprostane in the summer vs. other seasons. Inhibitors of NADPH oxidase, xanthine oxidase, and NO synthase inhibited the seasonal O(2)(-)-overproduction. In the summer vs. other seasons, cardiac NADPH oxidase and xanthine oxidase activity, and protein expression were increased, the endothelial NO synthase and superoxide dismutases were downregulated, and, in guinea-pig hearts, adhesion molecules upregulation and the endothelial glycocalyx destruction associated these changes. In guinea-pig hearts, the summer and a streptozotocin-induced diabetes mediated similar changes, yet, more severe endothelial activation associated the diabetes. These findings suggest that the seasonal oxidative stress is a common phenomenon, associated, at least in guinea-pigs, with the endothelial activation. Nonetheless, its biological meaning (regulatory vs. deleterious) remains unclear. Upregulated NADPH oxidase and xanthine oxidase and uncoupled NO synthase are the sources of the seasonal O(2)(-)-overproduction. Copyright © 2010 Elsevier Ltd. All rights reserved.

Monoamine oxidases: the biochemistry of the proteins as targets in medicinal chemistry and drug discovery.

PubMed

Ramsay, Rona R

2012-01-01

Monoamine oxidase (MAO, EC.1.4.3.4) has been a drug target for 60 years, with the primary rationale of developing drugs to treat neuropsychiatric disorders. The biological importance of MAO is to regulate amine levels is the brain and to metabolize amines and drugs in the periphery. This review of the biochemistry of MAO A and MAO B describes the functional properties of the two enzymes integrated with knowledge of the structures of the many MAOinhibitor complexes published in the last 10 years. The analysis of activity, and the chemical and kinetic mechanisms are discussed. Inhibition studies on human MAO in vitro are now facilitated by assays using readily available materials but the kinetics of MAO involving alternative oxidative pathways and sensitivity to the oxygen concentration mean that careful analysis of the data is required as well as the good practice of determining mechanism of inhibition and kinetic constants. Kinetic constants can then be compared with thermodynamic calculations. Inhibitors bind to both the oxidized and reduced forms of MAO present during turnover so both forms should be considered when using molecular dynamics to facilitate drug design. Interaction of inhibitors with the active site can be detected as changes in the visible spectrum and these changes can provide clues about the flavin adduct formed for irreversible inhibitors or about the proximity to the flavin for reversible inhibitors. Developing areas (knock-out mice for behavior, the imidazoline binding site, and imaging to monitor the activity and the inhibition of MAO in the patient) are mentioned.

Monoamine Oxidase and Dopamine β-Hydroxylase Inhibitors from the Fruits of Gardenia jasminoides

PubMed Central

Kim, Ji Ho; Kim, Gun Hee; Hwang, Keum Hee

2012-01-01

This research was designed to determine what components of Gardenia jasminoides play a major role in inhibiting the enzymes related antidepressant activity of this plant. In our previous research, the ethyl acetate fraction of G. jasminosides fruits inhibited the activities of both monoamine oxidase-A (MAO-A) and monoamine oxidase-B (MAO-B), and oral administration of the ethanolic extract slightly increased serotonin concentrations in the brain tissues of rats and decreased MAO-B activity. In addition, we found through in vitro screening test that the ethyl acetate fraction showed modest inhibitory activity on dopamine-β hydroxylase (DBH). The bioassay-guided fractionation led to the isolation of five bio-active compounds, protocatechuic acid (1), geniposide (2), 6'-O-trans-p-coumaroylgeniposide (3), 3,5-d-ihydroxy-1,7-bis (4-hydroxyphenyl) heptanes (4), and ursolic acid (5), from the ethyl acetate fraction of G. jasminoides fruits. The isolated compounds showed different inhibitory potentials against MAO-A, -B, and DBH. Protocatechuic acid showed potent inhibition against MAO-B (IC50 300 μmol/L) and DBH (334 μmol/L), exhibiting weak MAO-A inhibition (2.41 mmol/L). Two iridoid glycosides, geniposide (223 μmol/L) and 6'-O-trans-p-coumaroylgeniposide (127μmol/L), were selective MAO-B inhibitor. Especially, 6'-O-trans-p-coumaroylgeniposide exhibited more selective MAO-B inhibition than deprenyl, well-known MAO-B inhibitor for the treatment of early-stage Parkinson’s disease. The inhibitory activity of 3,5-di-hydroxy-1,7-bis (4-hydroxyphenyl) heptane was strong for MAO-B (196 μmol/L), modest for MAO-A (400 μmol/L), and weak for DBH (941 μmol/L). Ursolic acid exhibited significant inhibition of DBH (214 μmol/L), weak inhibition of MAO-B (780 μmol/L), and no inhibition against MAO-A. Consequently, G. jasminoides fruits are considerable for development of biofunctional food materials for the combination treatment of depression and neurodegenerative disorders. PMID:24116298

New insights into Brunner syndrome and potential for targeted therapy.

PubMed

Palmer, E E; Leffler, M; Rogers, C; Shaw, M; Carroll, R; Earl, J; Cheung, N W; Champion, B; Hu, H; Haas, S A; Kalscheuer, V M; Gecz, J; Field, M

2016-01-01

We report two families with Brunner syndrome living in one state of Australia. The first family had a predicted protein-truncating variant of monoamine oxidase A (MAOA) (p.S251KfsX2). Affected males had mild intellectual disability (ID), obsessive behaviour, limited friendships and were introverted and placid during clinical interview. The family disclosed episodic explosive aggression after a diagnosis was made. The second family had a missense variant in MAOA (p.R45W). Affected males had borderline-mild ID, attention deficit disorder and limited friendships. One had a history of explosive aggression in childhood and episodic symptoms of flushing, headaches and diarrhoea. Their carrier mother had normal intelligence but similar episodic symptoms. Characteristic biochemical abnormalities included high serum serotonin and urinary metanephrines and low urinary 5-hydroxyindoleacetic acid (5-HIAA) and vanillylmandelic acid (VMA). Symptomatic individuals in the second family had particularly high serotonin levels, and treatment with a serotonin reuptake inhibitor and dietary modification resulted in reversal of biochemical abnormalities, reduction of 'serotonergic' symptoms and behavioural improvement. Brunner syndrome should be considered as a cause of mild ID with paroxysmal behavioural symptoms. It can be screened for with serum/urine metanephrine and serotonin measurement. Cautious treatment with a serotonin reuptake inhibitor, dietary modifications and avoidance of medications contraindicated in patients on monoamine oxidase inhibitors can improve symptoms. © 2015 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Monoamine oxidase-B inhibition in the treatment of Parkinson's disease.

PubMed

Fernandez, Hubert H; Chen, Jack J

2007-12-01

Inhibitors of monoamine oxidase (MAO) with selectivity and specificity for MAO type B prolong the activity of both endogenously and exogenously derived dopamine, making them an option either as monotherapy in early Parkinson's disease or as adjunctive therapy in patients treated with levodopa who are experiencing motor complications. In addition to symptomatic benefits, experimental data suggest that MAO-B inhibitors may be neuroprotective through MAO-B inhibition and other mechanisms that have yet to be clearly defined. The two available MAO-B inhibitors approved for use in the United States, rasagiline and selegiline, each provide symptomatic relief as monotherapy and as adjunctive therapy, and have shown potential disease-modifying effects in experimental models and clinical studies. Selegiline in a conventional tablet formulation is less bioavailable than rasagiline, resulting in limited potency. It also has amphetamine metabolites that may produce adverse effects and interfere with any putative disease-modifying effects. The oral disintegrating tablet formulation of selegiline allows pregastric absorption, minimizing first-pass metabolism, thereby increasing selegiline bioavailability and reducing the concentration of amphetamine metabolites. Rasagiline, more potent than selegiline, exhibits disease-modifying effects in experimental models and lacks amphetamine metabolites. Both the symptomatic and potential disease-modifying effects of rasagiline are under investigation. A third agent with MAO-B inhibition properties, safinamide, is in phase III development. Although not yet approved, safinamide may offer the added advantage of combined MAO-B and dopamine reuptake inhibition.

Phenelzine (monoamine oxidase inhibitor) increases production of nitric oxide and proinflammatory cytokines via the NF-κB pathway in lipopolysaccharide-activated microglia cells.

PubMed

Chung, Hwan-Suck; Kim, Hyunseong; Bae, Hyunsu

2012-10-01

Phenelzine is a potent monoamine oxidase inhibitor that is used in patients with depression. It is also well known that nitric oxide (NO) synthase inhibitors show preclinical antidepressant-like properties, which suggests that NO is involved in the pathogenesis of depression. The purpose of this study was to determine if phenelzine affects the production of NO and tumor necrosis factor-alpha (TNF-α) in activated microglia cells. BV-2 microglia cells and primary microglia cells were cultured in DMEM and DMEM/F12 and then cells were treated with LPS or LPS plus phenelzine for 24 h. The culture medium was collected for determination of NO, TNF-α, and IL-6 and cells were harvested by lysis buffer for Western blot analysis. Phenelzine increased the lipopolysaccharide (LPS)-induced expression of inducible nitric oxide synthase (iNOS), as well as the release of TNF-α and IL-6 in BV-2 microglia cells. It is also confirmed that phenelzine increased the levels of NO, TNF-α and IL-6 in LPS-activated primary microglia cells. Phenelzine increased nuclear translocation of NF-κB by phosphorylation of IκB-α in LPS-activated microglia cells. These findings suggest that high doses of phenelzine could aggravate inflammatory responses in microglia cells that are mediated by NO and TNF-α.

Electrophysiological effects of monoamine oxidase inhibition on rat midbrain dopaminergic neurones: an in vitro study.

PubMed Central

Mercuri, N. B.; Bonci, A.; Siniscalchi, A.; Stefani, A.; Calabresi, P.; Bernardi, G.

1996-01-01

1 The effects of the inhibition of monoamine oxidase (MAO) type A and B have been evaluated on the spontaneous firing activity of the dopaminergic (principal) neurones of the rat midbrain intracellularly recorded from a slice preparation. 2 The non-specific MAO inhibitor, pargyline, superfused at a concentration of 10-100 microM, decreased or abolished the spontaneous firing discharge of the principal neurons in the subtantia nigra pars compacta and ventral tegmental area. This effect had a slow onset and appeared to be sustained. 3 The administration of the dopamine D2/3 receptor antagonist, sulpiride (100-300 nM), antagonized the pargyline-induced effect, while the superfusion of the dopamine D1 receptor antagonist, SCH 23390 (1-3 microM) did not counteract the induced inhibition of the firing rate. 4 The inhibitor for the MAO A, clorgyline (30-100 microM), reduced the firing rate of the dopaminergic neurones. A similar depressant effect was also observed when a MAO B inhibitor, deprenyl (30-100 microM), was applied. Lower concentrations of both drugs (300 nM-10 microM) did not produce consistent effects on neuronal discharge. 5 Our data suggest that only the blockade of both types of MAO enzymes favours the inhibitory action of endogenous dopamine on somato-dendritic D2/3 autoreceptors. PMID:8821544

[Not Available].

PubMed

Charbonneau, Annie

2013-07-01

Methylene blue is used in medical practice for various reasons. Recent findings point to a potential interaction with serotonin reuptake inhibitors (SRIs) that could lead to serotonergic toxicity. To describe the risk of serotonergic toxicity associated with the interaction between methylene blue and SRIs. Relevant publications were searched systematically via MEDLINE (1946 to March 21, 2013) and Embase (1974 to 2013, week 11) with the following search terms: "methylene blue", "methylthioninium", "monoamine oxidase inhibitors", "serotonin reup-take inhibitors", and "serotonin syndrome". No restrictions were applied in relation to the indication for methylene blue or the language of publication. The reference lists of identified articles were also searched. Eighteen case reports and 2 case series were identified for inclusion. To date, no randomized controlled trials have been published. The first case report indicating suspicion of an interaction between methylene blue and SRIs was published in 2003. Seventeen other case reports describing the same type of interaction have been published since then. The 2 case series provided data from about 325 parathyroidectomies in which methylene blue was used for staining. The 17 patients who experienced central nervous system toxicity were all taking SRIs in the preoperative period. When administered in combination with SRIs, methylene blue may lead to serotonergic toxicity at doses as low as 0.7 mg/kg. Methylene blue would seem to have monoamine oxidase A inhibitory properties. Precautions should be taken to avoid this interaction. [Publisher's translation].

Evidence for glycosylation as a regulator of the pigmentary system: key roles of sialyl(α2-6)gal/GalNAc-terminated glycans in melanin synthesis and transfer.

PubMed

Diwakar, Ganesh; Klump, Vincent; Lazova, Rossitza; Pawelek, John

2015-08-01

The major regulators of melanogenesis are glycoproteins, however no role for glycosylation in the pathway has yet been described. We stained skin biopsies and melanocyte-keratinocyte co-cultures with a panel of 20 lectins as oligosaccharide markers. Notably, the Elderberry Bark Lectin (EBL/SNA) stained melanocytes in both systems. EBL binds the sequence Neu5Ac(α(2-6)Gal/GalNAc)- at the termini of some oligosaccharide antennae. We used inhibitors of synthesis and/or binding of this sequence to assess effects on pigmentation. Cell culture, lectin histochemistry, siRNA transfection, and assays for dopa oxidase and melanin were carried out by standard techniques. 6'-sialyllactose, a short homolog of the sequence in question, anti-sialyltransferase 6 (ST6) siRNA, and cytidine, a sialyltransferase (ST) inhibitor, each inhibited EBL binding, melanogenesis and melanosome transfer. Unexpectedly, 3'-sialyllactose and siRNA for ST3, chosen as a negative controls, also inhibited these processes. Though strong inhibitors of melanization, none of the agents affected tyrosinase/dopa oxidase activity, indicating previously unrecognized post-tyrosinase regulation of melanization. We report for the first time that Neu5Ac (α(2-6)Gal/GalNAc)- and possibly Neu5Ac(α(2-3)Gal/GalNAc)-terminated oligosaccharides play multiple roles in melanin synthesis and transfer.

Low-Dose Dextromethorphan, a NADPH Oxidase Inhibitor, Reduces Blood Pressure and Enhances Vascular Protection in Experimental Hypertension

PubMed Central

Wu, Tao-Cheng; Chao, Chih-Yu; Lin, Shing-Jong; Chen, Jaw-Wen

2012-01-01

Background Vascular oxidative stress may be increased with age and aggravate endothelial dysfunction and vascular injury in hypertension. This study aimed to investigate the effects of dextromethorphan (DM), a NADPH oxidase inhibitor, either alone or in combination treatment, on blood pressure (BP) and vascular protection in aged spontaneous hypertensive rats (SHRs). Methodology/Principal Findings Eighteen-week-old WKY rats and SHRs were housed for 2 weeks. SHRs were randomly assigned to one of the 12 groups: untreated; DM monotherapy with 1, 5 or 25 mg/kg/day; amlodipine (AM, a calcium channel blocker) monotherapy with 1 or 5 mg/kg/day; and combination therapy of DM 1, 5 or 25 mg/kg/day with AM 1 or 5 mg/kg/day individually for 4 weeks. The in vitro effects of DM were also examined. In SHRs, AM monotherapy dose-dependently reduced arterial systolic BP. DM in various doses significantly and similarly reduced arterial systolic BP. Combination of DM with AM gave additive effects on BP reduction. DM, either alone or in combination with AM, improved aortic endothelial function indicated by ex vivo acetylcholine-induced relaxation. The combination of low-dose DM with AM gave most significant inhibition on aortic wall thickness in SHRs. Plasma total antioxidant status was significantly increased by all the therapies except for the combination of high-dose DM with high-dose AM. Serum nitrite and nitrate level was significantly reduced by AM but not by DM or the combination of DM with AM. Furthermore, in vitro treatment with DM reduced angiotensin II-induced reactive oxygen species and NADPH oxidase activation in human aortic endothelial cells. Conclusions/Significance Treatment of DM reduced BP and enhanced vascular protection probably by inhibiting vascular NADPH oxidase in aged hypertensive animals with or without AM treatment. It provides the potential rationale to a novel combination treatment with low-dose DM and AM in clinical hypertension. PMID:23049937

EPA:DHA 6:1 prevents angiotensin II-induced hypertension and endothelial dysfunction in rats: role of NADPH oxidase- and COX-derived oxidative stress.

PubMed

Niazi, Zahid Rasul; Silva, Grazielle C; Ribeiro, Thais Porto; León-González, Antonio J; Kassem, Mohamad; Mirajkar, Abdur; Alvi, Azhar; Abbas, Malak; Zgheel, Faraj; Schini-Kerth, Valérie B; Auger, Cyril

2017-12-01

Eicosapentaenoic acid:docosahexaenoic acid (EPA:DHA) 6:1, an omega-3 polyunsaturated fatty acid formulation, has been shown to induce a sustained formation of endothelial nitric oxide (NO) synthase-derived NO, a major vasoprotective factor. This study examined whether chronic intake of EPA:DHA 6:1 prevents hypertension and endothelial dysfunction induced by angiotensin II (Ang II) in rats. Male Wister rats received orally corn oil or EPA:DHA 6:1 (500 mg kg -1 per day) before chronic infusion of Ang II (0.4 mg kg -1 per day). Systolic blood pressure was determined by tail cuff sphingomanometry, vascular reactivity using a myograph, oxidative stress using dihydroethidium and protein expression by immunofluorescence and western blot analysis. Ang II-induced hypertension was associated with reduced acetylcholine-induced relaxations of secondary branch mesenteric artery rings affecting the endothelium-dependent hyperpolarization (EDH)- and the NO-mediated relaxations, both of which were improved by the NADPH oxidase inhibitor VAS-2870. The Ang II treatment induced also endothelium-dependent contractile responses (EDCFs), which were abolished by the cyclooxygenase (COX) inhibitor indomethacin. An increased level of vascular oxidative stress and expression of NADPH oxidase subunits (p47 phox and p22 phox ), COX-1 and COX-2, endothelial NO synthase and Ang II type 1 receptors were observed in the Ang II group, whereas SK Ca and connexin 37 were downregulated. Intake of EPA:DHA 6:1 prevented the Ang II-induced hypertension and endothelial dysfunction by improving both the NO- and EDH-mediated relaxations, and by reducing EDCFs and the expression of target proteins. The present findings indicate that chronic intake of EPA:DHA 6:1 prevented the Ang II-induced hypertension and endothelial dysfunction in rats, most likely by preventing NADPH oxidase- and COX-derived oxidative stress.

Targeting NADPH oxidase decreases oxidative stress in the transgenic sickle cell mouse penis.

PubMed

Musicki, Biljana; Liu, Tongyun; Sezen, Sena F; Burnett, Arthur L

2012-08-01

Sickle cell disease (SCD) is a state of chronic vasculopathy characterized by endothelial dysfunction and increased oxidative stress, but the sources and mechanisms responsible for reactive oxygen species (ROS) production in the penis are unknown. We evaluated whether SCD activates NADPH oxidase, induces endothelial nitric oxide synthase (eNOS) uncoupling, and decreases antioxidants in the SCD mouse penis. We further tested the hypothesis that targeting NADPH oxidase decreases oxidative stress in the SCD mouse penis. SCD transgenic (sickle) mice were used as an animal model of SCD. Hemizygous (hemi) mice served as controls. Mice received an NADPH oxidase inhibitor apocynin (10 mM in drinking water) or vehicle. Penes were excised at baseline for molecular studies. Markers of oxidative stress (4-hydroxy-2-nonenal [HNE]), sources of ROS (eNOS uncoupling and NADPH oxidase subunits p67(phox) , p47(phox) , and gp91(phox) ), and enzymatic antioxidants (superoxide dismutase [SOD]1, SOD2, catalase, and glutathione peroxidase-1 [GPx1]) were measured by Western blot in penes. Sources of ROS, oxidative stress, and enzymatic antioxidants in the SCD penis. Relative to hemi mice, SCD increased (P<0.05) protein expression of NADPH oxidase subunits p67(phox) , p47(phox) , and gp91(phox) , 4-HNE-modified proteins, induced eNOS uncoupling, and reduced Gpx1 expression in the penis. Apocynin treatment of sickle mice reversed (P<0.05) the abnormalities in protein expressions of p47(phox) , gp91(phox) (but not p67(phox) ) and 4-HNE, but only slightly (P>0.05) prevented eNOS uncoupling in the penis. Apocynin treatment of hemi mice did not affect any of these parameters. NADPH oxidase and eNOS uncoupling are sources of oxidative stress in the SCD penis; decreased GPx1 further contributes to oxidative stress. Inhibition of NADPH oxidase upregulation decreases oxidative stress, implying a major role for NADPH oxidase as a ROS source and a potential target for improving vascular function in the SCD mouse penis. © 2012 International Society for Sexual Medicine.

Targeting NADPH Oxidase Decreases Oxidative Stress in the Transgenic Sickle Cell Mouse Penis

PubMed Central

Musicki, Biljana; Liu, Tongyun; Sezen, Sena F.; Burnett, Arthur L.

2012-01-01

Introduction Sickle cell disease (SCD) is a state of chronic vasculopathy characterized by endothelial dysfunction and increased oxidative stress, but the sources and mechanisms responsible for reactive oxygen species (ROS) production in the penis are unknown. Aims We evaluated whether SCD activates NADPH oxidase, induces endothelial nitric oxide synthase (eNOS) uncoupling, and decreases antioxidants in the SCD mouse penis. We further tested the hypothesis that targeting NADPH oxidase decreases oxidative stress in the SCD mouse penis. Methods SCD transgenic (sickle) mice were used as an animal model of SCD. Hemizygous (hemi) mice served as controls. Mice received an NADPH oxidase inhibitor apocynin (10 mM in drinking water) or vehicle. Penes were excised at baseline for molecular studies. Markers of oxidative stress (4-hydroxy-2-nonenal [HNE]), sources of ROS (eNOS uncoupling and NADPH oxidase subunits p67phox, p47phox, and gp91phox), and enzymatic antioxidants (superoxide dismutase [SOD]1, SOD2, catalase, and glutathione peroxidase-1 [GPx1]) were measured by Western blot in penes. Main Outcome Measures Sources of ROS, oxidative stress, and enzymatic antioxidants in the SCD penis. Results Relative to hemi mice, SCD increased (P < 0.05) protein expression of NADPH oxidase subunits p67phox, p47phox, and gp91phox, 4-HNE-modified proteins, induced eNOS uncoupling, and reduced Gpx1 expression in the penis. Apocynin treatment of sickle mice reversed (P < 0.05) the abnormalities in protein expressions of p47phox, gp91phox (but not p67phox) and 4-HNE, but only slightly (P > 0.05) prevented eNOS uncoupling in the penis. Apocynin treatment of hemi mice did not affect any of these parameters. Conclusion NADPH oxidase and eNOS uncoupling are sources of oxidative stress in the SCD penis; decreased GPx1 further contributes to oxidative stress. Inhibition of NADPH oxidase upregulation decreases oxidative stress, implying a major role for NADPH oxidase as a ROS source and a potential target for improving vascular function in the SCD mouse penis. PMID:22620981

MAO inhibitors and their wider applications: a patent review.

PubMed

Carradori, Simone; Secci, Daniela; Petzer, Jacques P

2018-03-01

Monoamine oxidase (MAO) inhibitors, after the initial 'golden age', are currently used as third-line antidepressants (selective MAO-A inhibitors) or clinically enrolled as co-adjuvants for neurodegenerative diseases (selective MAO-B inhibitors). However, the research within this field is always increasing due to their pivotal role in modulating synaptic functions and monoamines metabolism. Areas covered: In this paper, MAO inhibitors (2015-2017) are disclosed ordering all the patents according to their chemical scaffold. Structure-activity relationships (SARs) are extrapolated for the most investigated chemotypes (coumarins, pyrazole/oxazepinones, (hetero)arylamides). 108 Compounds are divided into two main groups: newly synthesized molecules and naturally-occurring metabolites. Finally, new therapeutic options are outlined to ensure a more complete view on the potential of these inhibitors. Expert opinion: New proposed MAO inhibitors are endowed with a marked isoform selectivity, with innovative therapeutic potential toward other targets (gliomas, inflammation, muscle dystrophies, migraine, chronic pain, pseudobulbar affect), and with a promising ability to address multi-faceted pathologies such as Alzheimer's disease. The increasing number of patents is analyzed collecting data from 2002 to 2017.

Characterization of 1-Aminobenzotriazole and Ketoconazole as Novel Inhibitors of Monoamine Oxidase (MAO): An In Vitro Investigation.

PubMed

Shaik, Abdul Naveed; LeDuc, Barbara W; Khan, Ansar A

2017-10-01

1-Aminobenzotriazole, a known time-dependent inhibitor of cytochrome P450 (CYP) enzymes, and ketoconazole, a strong inhibitor of the human CYP3A4 isozyme, are used as standard probe inhibitors to characterize the CYP and/or non-CYP-mediated metabolism of xenobiotics. In the present investigation, 1-Aminobenzotriazole and ketoconazole are characterized as potent monoamine oxidase (MAO) inhibitors in vitro using mouse, rat and human liver microsomes and S9 fractions. Inhibition potential of 1-aminobenzotriazole and ketoconazole was studied in mice, rat and human liver microsomes, S9 fractions, MAO-A and MAO-B expressed enzymes by monitoring the formation of 4-hydroxyquinoline (4-HQ) from kynuramine, a specific substrate of MAO by liquid chromatography-tandem mass spectrometry (LC-MS/MS). Mechanism of MAO inhibition was studied by incubating varying concentration of kynuramine with mouse, rat and human S9 fractions at varying concentration of 1-aminobenzatriazole and ketoconazole and monitoring the formation of 4-HQ. 1-aminobenzotriazole and ketoconazole inhibited both MAO isozymes (MAO-A and MAO-B) with more specificity towards MAO-B. Kynuramine substrate kinetics in mouse, rat and human S9 fractions with varying 1-aminobenzotriazole and ketoconazole concentrations showed decreased maximum rate (V max ) for 4-HQ formation without affecting the Michaelis-Menten constant (K m ). A non-competitive inhibition model was constructed and inhibition constants (K i ) for 1-aminobenzotriazole (7.87 ± 0.61, 8.61 ± 0.92, 65.2 ± 1.61 µM for mice, rat and humans, respectively) and ketoconazole (0.12 ± 0.01, 2.04 ± 0.08, 5.52 ± 0.47 µM for mice, rat and humans, respectively) were determined. 1-Aminobenzotriazole and ketoconazole are characterized as non-competitive inhibitors of mice, rat and human MAO in vitro and the extent of their MAO inhibition potential is species specific. 1-Aminobenzotriazole or ketoconazole can be used as a probe inhibitor in vitro for screening the involvement of MAO-dependent metabolism of new chemical entities (NCE) in early drug discovery.

Age-dependent redox status in the brain stem of NO-deficient hypertensive rats.

PubMed

Majzúnová, Miroslava; Pakanová, Zuzana; Kvasnička, Peter; Bališ, Peter; Čačányiová, Soňa; Dovinová, Ima

2017-09-11

The brain stem contains important nuclei that control cardiovascular function via the sympathetic nervous system (SNS), which is strongly influenced by nitric oxide. Its biological activity is also largely determined by oxygen free radicals. Despite many experimental studies, the role of AT1R-NAD(P)H oxidase-superoxide pathway in NO-deficiency is not yet sufficiently clarified. We determined changes in free radical signaling and antioxidant and detoxification response in the brain stem of young and adult Wistar rats during chronic administration of exogenous NO inhibitors. Young (4 weeks) and adult (10 weeks) Wistar rats were treated with 7-nitroindazole (7-NI group, 10 mg/kg/day), a specific nNOS inhibitor, with N G -nitro-L-arginine-methyl ester (L-NAME group, 50 mg/kg/day), a nonspecific NOS inhibitor, and with drinking water (Control group) during 6 weeks. Systolic blood pressure was measured by non-invasive plethysmography. Expression of genes (AT1R, AT2R, p22phox, SOD and NOS isoforms, HO-1, MDR1a, housekeeper GAPDH) was identified by real-time PCR. NOS activity was detected by conversion of [3H]-L-arginine to [3H]-L-citrulline and SOD activity was measured using UV VIS spectroscopy. We observed a blood pressure elevation and decrease in NOS activity only after L-NAME application in both age groups. Gene expression of nNOS (youngs) and eNOS (adults) in the brain stem decreased after both inhibitors. The radical signaling pathway triggered by AT1R and p22phox was elevated in L-NAME adults, but not in young rats. Moreover, L-NAME-induced NOS inhibition increased antioxidant response, as indicated by the observed elevation of mRNA SOD3, HO-1, AT2R and MDR1a in adult rats. 7-NI did not have a significant effect on AT1R-NADPH oxidase-superoxide pathway, yet it affected antioxidant response of mRNA expression of SOD1 and stimulated total activity of SOD in young rats and mRNA expression of AT2R in adult rats. Our results show that chronic NOS inhibition by two different NOS inhibitors has age-dependent effect on radical signaling and antioxidant/detoxificant response in Wistar rats. While 7-NI had neuroprotective effect in the brain stem of young Wistar rats, L-NAME- induced NOS inhibition evoked activation of AT1R-NAD(P)H oxidase pathway in adult Wistar rats. Triggering of the radical pathway was followed by activation of protective compensation mechanism at the gene expression level.

Design, synthesis and inhibitory activities of 8-(substituted styrol-formamido)phenyl-xanthine derivatives on monoamine oxidase B.

PubMed

Hu, Suwen; Nian, Siyun; Qin, Kuiyou; Xiao, Tong; Li, Lingna; Qi, Xiaolu; Ye, Faqing; Liang, Guang; Hu, Guoxin; He, Jincai; Yu, Yinfei; Song, Bo

2012-01-01

The design and synthesis of two series of 8-(substituted styrol-formamido)phenyl-xanthine derivatives are described. Their in vitro monoamine oxidase B (MAO-B) inhibition were tested and the effect of substituents on the N-7, phenyl and the substituted positions are discussed. It was observed that compound 9b displayed significant MAO-B inhibition activity and selectivity, fluorine substitution plays a key role in the selectivity of MAO-B inhibition, and the styrol-formamido group at position-3' may enhance the activity and selectivity of 8-phenyl-xanthine analogues. These results suggest that such compounds may be utilized for the development of new candidate MAO-B inhibitors for treatment of Parkinson's disease.

Characterization of oxidative phosphorylation enzymes in Euglena gracilis and its white mutant strain W(gm)ZOflL.

PubMed

Krnáčová, Katarína; Rýdlová, Ivana; Vinarčíková, Michaela; Krajčovič, Juraj; Vesteg, Matej; Horváth, Anton

2015-03-12

The enzymes involved in Euglena oxidative phosphorylation (OXPHOS) were characterized in this study. We have demonstrated that Euglena gracilis strain Z and its stable bleached non-photosynthetic mutant strain WgmZOflL both possess fully functional OXPHOS apparatus as well as pathways requiring terminal alternative oxidase(s) and alternative mitochondrial NADH-dehydrogenase(s). Light (or dark) and plastid (non)functionality seem to have little effect on oxygen consumption, the activities of the enzymes involved in OXPHOS and the action of respiration inhibitors in Euglena. This study also demonstrates biochemical properties of complex III (cytochrome c reductase) in Euglena. Copyright © 2015 Federation of European Biochemical Societies. Published by Elsevier B.V. All rights reserved.

Fatal combination of moclobemide overdose and whisky.

PubMed

Bleumink, G S; van Vliet, A C M; van der Tholen, A; Stricker, B H Ch

2003-03-01

The antidepressant moclobemide (Aurorix) is a reversible inhibitor of monoamine oxidase-A. Pure moclobemide overdose is considered to be relatively safe. Mixed drug overdoses including moclobemide are potentially lethal, especially when serotonergical drugs are involved. So far, only one fatality due to moclobemide mono-overdose has been reported. We report here on a fatality following the ingestion of a moclobemide overdose in combination with half a bottle of whisky. Although dietary restrictions during moclobemide therapy are not considered necessary, the combination of large quantities of moclobemide and tyramine-containing products seems to be lethal, probably because monoamine oxidase-A selectivity is overwhelmed after massive overdoses. Since there is no specific antidote and treatment is only symptomatic, the severity of an overdose with moclobemide must not be underestimated.

Spectral and catalytic properties of aryl-alcohol oxidase, a fungal flavoenzyme acting on polyunsaturated alcohols

PubMed Central

2005-01-01

Spectral and catalytic properties of the flavoenzyme AAO (aryl-alcohol oxidase) from Pleurotus eryngii were investigated using recombinant enzyme. Unlike most flavoprotein oxidases, AAO does not thermodynamically stabilize a flavin semiquinone radical and forms no sulphite adduct. AAO catalyses the oxidative dehydrogenation of a wide range of unsaturated primary alcohols with hydrogen peroxide production. This differentiates the enzyme from VAO (vanillyl-alcohol oxidase), which is specific for phenolic compounds. Moreover, AAO is optimally active in the pH range of 5–6, whereas VAO has an optimum at pH 10. Kinetic studies showed that AAO is most active with p-anisyl alcohol and 2,4-hexadien-1-ol. AAO converts m- and p-chlorinated benzyl alcohols at a similar rate as it does benzyl alcohol, but introduction of a p-methoxy substituent in benzyl alcohol increases the reaction rate approx. 5-fold. AAO also exhibits low activity on aromatic aldehydes. 19F NMR analysis showed that fluorinated benzaldehydes are converted into the corresponding benzoic acids. Inhibition studies revealed that the AAO active site can bind a wide range of aromatic ligands, chavicol (4-allylphenol) and p-anisic (4-methoxybenzoic) acid being the best competitive inhibitors. Uncompetitive inhibition was observed with 4-methoxybenzylamine. The properties described above render AAO a unique oxidase. The possible mechanism of AAO binding and oxidation of substrates is discussed in the light of the results of the inhibition and kinetic studies. PMID:15813702

Indoxyl sulfate potentiates endothelial dysfunction via reciprocal role for reactive oxygen species and RhoA/ROCK signaling in 5/6 nephrectomized rats.

PubMed

Chu, Shuang; Mao, Xiaodong; Guo, Hengjiang; Wang, Li; Li, Zezheng; Zhang, Yang; Wang, Yunman; Wang, Hao; Zhang, Xuemei; Peng, Wen

2017-03-01

Accumulative indoxyl sulfate (IS) retained in chronic kidney disease (CKD) can potentiate vascular endothelial dysfunction, and herein, we aim at elucidating the underlying mechanisms from the perspective of possible association between reactive oxygen species (ROS) and RhoA/ROCK pathway. IS-treated nephrectomized rats are administered with antioxidants including NADPH oxidase inhibitor apocynin, SOD analog tempol, and mitochondrion-targeted SOD mimetic mito-TEMPO to scavenge ROS, or ROCK inhibitor fasudil to obstruct RhoA/ROCK pathway. First, we find in response to IS stimulation, antioxidants treatments suppress increased aortic ROCK activity and expression levels. Additionally, ROCK blockade prevent IS-induced increased NADPH oxidase expression (mainly p22phox and p47phox), mitochondrial and intracellular ROS (superoxide and hydrogen peroxide) generation, and decreased Cu/Zn-SOD expression in thoracic aortas. Apocynin, mito-TEMPO, and tempol also reverse these markers of oxidative stress. These results suggest that IS induces excessive ROS production and ROCK activation involving a circuitous relationship in which ROS activate ROCK and ROCK promotes ROS overproduction. Finally, ROS and ROCK depletion attenuate IS-induced decrease in nitric oxide (NO) production and eNOS expression levels, and alleviate impaired vasomotor responses including increased vasocontraction to phenylephrine and decreased vasorelaxation to acetylcholine, thereby preventing cardiovascular complications accompanied by CKD. Taken together, excessive ROS derived from NADPH oxidase and mitochondria coordinate with RhoA/ROCK activation in a form of positive reciprocal relationship to induce endothelial dysfunction through disturbing endothelium-dependent NO signaling upon IS stimulation in CKD status.

Pharmacophore modeling, molecular docking and molecular dynamics studies on natural products database to discover novel skeleton as non-purine xanthine oxidase inhibitors.

PubMed

Peng, Jiale; Li, Yaping; Zhou, Yeheng; Zhang, Li; Liu, Xingyong; Zuo, Zhili

2018-05-29

Gout is a common inflammatory arthritis caused by the deposition of urate crystals within joints. It is increasingly in prevalence during the past few decades as shown by the epidemiological survey results. Xanthine oxidase (XO) is a key enzyme to transfer hypoxanthine and xanthine to uric acid, whose overproduction leads to gout. Therefore, inhibiting the activity of xanthine oxidase is an important way to reduce the production of urate. In the study, in order to identify the potential natural products targeting XO, pharmacophore modeling was employed to filter databases. Here, two methods, pharmacophore based on ligand and pharmacophore based on receptor-ligand, were constructed by Discovery Studio. Then GOLD was used to refine the potential compounds with higher fitness scores. Finally, molecular docking and dynamics simulations were employed to analyze the interactions between compounds and protein. The best hypothesis was set as a 3D query to screen database, returning 785 and 297 compounds respectively. A merged set of the above 1082 molecules was subjected to molecular docking, which returned 144 hits with high-fitness scores. These molecules were clustered in four main kinds depending on different backbones. What is more, molecular docking showed that the representative compounds established key interactions with the amino acid residues in the protein, and the RMSD and RMSF of molecular dynamics results showed that these compounds can stabilize the protein. The information represented in the study confirmed previous reports. And it may assist to discover and design new backbones as potential XO inhibitors based on natural products.

Effects of allopurinol on exercise-induced muscle damage: new therapeutic approaches?

PubMed

Sanchis-Gomar, F; Pareja-Galeano, H; Perez-Quilis, C; Santos-Lozano, A; Fiuza-Luces, C; Garatachea, N; Lippi, G; Lucia, A

2015-01-01

Intensive muscular activity can trigger oxidative stress, and free radicals may hence be generated by working skeletal muscle. The role of the enzyme xanthine oxidase as a generating source of free radicals is well documented and therefore is involved in the skeletal muscle damage as well as in the potential transient cardiovascular damage induced by high-intensity physical exercise. Allopurinol is a purine hypoxanthine-based structural analog and a well-known inhibitor of xanthine oxidase. The administration of the xanthine oxidase inhibitor allopurinol may hence be regarded as promising, safe, and an economic strategy to decrease transient skeletal muscle damage (as well as heart damage, when occurring) in top-level athletes when administered before a competition or a particularly high-intensity training session. Although continuous administration of allopurinol in high-level athletes is not recommended due to its possible role in hampering training-induced adaptations, the drug might be useful in non-athletes. Exertional rhabdomyolysis is the most common form of rhabdomyolysis and affects individuals participating in a type of intense exercise to which they are not accustomed. This condition can cause exercise-related myoglobinuria, thus increasing the risk of acute renal failure and is also associated with sickle cell trait. In this manuscript, we have reviewed the recent evidence about the effects of allopurinol on exercise-induced muscle damage. More research is needed to determine whether allopurinol may be useful for preventing not only exertional rhabdomyolysis and acute renal damage but also skeletal muscle wasting in critical illness as well as in immobilized, bedridden, sarcopenic or cachectic patients.

The xanthine oxidase inhibitor Febuxostat reduces tissue uric acid content and inhibits injury-induced inflammation in the liver and lung

PubMed Central

Kataoka, Hiroshi; Yang, Ke; Rock, Kenneth L.

2014-01-01

Necrotic cell death in vivo induces a robust neutrophilic inflammatory response and the resulting inflammation can cause further tissue damage and disease. Dying cells induce this inflammation by releasing pro-inflammatory intracellular components, one of which is uric acid. Cells contain high levels of intracellular uric acid, which is produced when purines are oxidized by the enzyme xanthine oxidase. Here we test whether a non-nucleoside xanthine oxidase inhibitor, Febuxostat (FBX), can reduce intracellular uric acid levels and inhibit cell death-induced inflammation in two different murine tissue injury models; acid-induced acute lung injury and acetaminophen liver injury. Infiltration of inflammatory cells induced by acid injection into lungs or peritoneal administration of acetaminophen was evaluated by quantification with flow cytometry and tissue myeloperoxidase activity in the presence or absence of FBX treatment. Uric acid levels in serum and tissue were measured before giving the stimuli and during inflammation. The impact of FBX treatment on the peritoneal inflammation caused by the microbial stimulus, zymosan, was also analyzed to see whether FBX had a broad anti-inflammatory effect. We found that FBX reduced uric acid levels in acid-injured lung tissue and inhibited acute pulmonary inflammation triggered by lung injury. Similarly, FBX reduced uric acid levels in the liver and inhibited inflammation in response to acetaminophen-induced hepatic injury. In contrast, FBX did not reduce inflammation to zymosan, and therefore is not acting as a general anti-inflammatory agent. These results point to the potential of using agents like FBX to treat cell death-induced inflammation. PMID:25449036

Electrophysiological characterization of harmane-induced activation of mesolimbic dopamine neurons.

PubMed

Arib, Ouafa; Rat, Pascal; Molimard, Robert; Chait, Abderrahman; Faure, Philippe; de Beaurepaire, Renaud

2010-03-10

It has been suggested that the beta-carbolines harmane and norharmane may be involved in the pathophysiology of Parkinson's disease, psychosis and addiction, but the mechanisms of these possible effects remain to be elucidated. In the present study, the effects of the two compounds were examined by using in vivo extracellular recordings of ventral tegmental dopamine neurons. The effects of harmane (2mg/kg) and norharmane (2mg/kg), were compared to those of nicotine (11microg/kg), of cotinine (0.5mg/kg), of the monoamine-oxidase-A inhibitor befloxatone (0.12mg/kg), and of the monoamine-oxidase-B inhibitor selegiline (0.5mg/kg). The effects of harmane were also tested after pre-treatment with the nicotine receptor antagonist mecamylamine. The results show that all substances, except befloxatone, activate the firing and/or burst activity of dopamine neurons. The increase in firing rate produced by harmane was approximately 18 times greater than that produced by nicotine. Such powerful excitation of dopamine neurons by harmane may in part explain its involvement in neurotoxicity, psychosis and addiction. The absence of effect of befloxatone supports the hypothesis that the effect of harmane is not related to its monoamine-oxidase-A inhibitory properties. Mecamylamine inhibited by approximately 80% the activity of harmane, indicating that the activating effect of harmane on dopamine neurons involves several mechanisms, among which activation of nicotinic receptors likely has a prominent importance. The results of the present study support the hypothesis that harmane could be a tobacco (or smoke) component other than nicotine involved in tobacco dependence. Copyright (c) 2009 Elsevier B.V. All rights reserved.

Sevoflurane postconditioning improves myocardial mitochondrial respiratory function and reduces myocardial ischemia-reperfusion injury by up-regulating HIF-1

PubMed Central

Yang, Long; Xie, Peng; Wu, Jianjiang; Yu, Jin; Yu, Tian; Wang, Haiying; Wang, Jiang; Xia, Zhengyuan; Zheng, Hong

2016-01-01

Background: Sevoflurane postconditioning (SPostC) can exert myocardial protective effects similar to ischemic preconditioning. However, the exact myocardial protection mechanism by SPostC is unclear. Studies indicate that hypoxia-inducible factor-1 (HIF-1) maintains cellular respiration homeostasis by regulating mitochondrial respiratory chain enzyme activity under hypoxic conditions. This study investigated whether SPostC could regulate the expression of myocardial HIF-1α and to improve mitochondrial respiratory function, thereby relieving myocardial ischemia-reperfusion injury in rats. Methods: The myocardial ischemia-reperfusion rat model was established using the Langendorff isolated heart perfusion apparatus. Additionally, postconditioning was performed using sevoflurane alone or in combination with the HIF-1α inhibitor 2-methoxyestradiol (2ME2). The changes in hemodynamic parameters, HIF-1α protein expression levels, mitochondrial respiratory function and enzyme activity, mitochondrial reactive oxygen species (ROS) production rates, and mitochondrial ultrastructure were measured or observed. Results: Compared to the ischemia-reperfusion (I/R) group, HIF-1α expression in the SPostC group was significantly up-regulated. Additionally, cardiac function indicators, mitochondrial state 3 respiratory rate, respiratory control ratio (RCR), cytochrome C oxidase (CcO), NADH oxidase (NADHO), and succinate oxidase (SUCO) activities, mitochondrial ROS production rate, and mitochondrial ultrastructure were significantly better than those in the I/R group. However, these advantages were completely reversed by the HIF-1α specific inhibitor 2ME2 (P<0.05). Conclusion: The myocardial protective function of SPostC might be associated with the improvement of mitochondrial respiratory function after up-regulation of HIF-1α expression. PMID:27830025

Sevoflurane postconditioning improves myocardial mitochondrial respiratory function and reduces myocardial ischemia-reperfusion injury by up-regulating HIF-1.

PubMed

Yang, Long; Xie, Peng; Wu, Jianjiang; Yu, Jin; Yu, Tian; Wang, Haiying; Wang, Jiang; Xia, Zhengyuan; Zheng, Hong

2016-01-01

Sevoflurane postconditioning (SPostC) can exert myocardial protective effects similar to ischemic preconditioning. However, the exact myocardial protection mechanism by SPostC is unclear. Studies indicate that hypoxia-inducible factor-1 (HIF-1) maintains cellular respiration homeostasis by regulating mitochondrial respiratory chain enzyme activity under hypoxic conditions. This study investigated whether SPostC could regulate the expression of myocardial HIF-1α and to improve mitochondrial respiratory function, thereby relieving myocardial ischemia-reperfusion injury in rats. The myocardial ischemia-reperfusion rat model was established using the Langendorff isolated heart perfusion apparatus. Additionally, postconditioning was performed using sevoflurane alone or in combination with the HIF-1α inhibitor 2-methoxyestradiol (2ME2). The changes in hemodynamic parameters, HIF-1α protein expression levels, mitochondrial respiratory function and enzyme activity, mitochondrial reactive oxygen species (ROS) production rates, and mitochondrial ultrastructure were measured or observed. Compared to the ischemia-reperfusion (I/R) group, HIF-1α expression in the SPostC group was significantly up-regulated. Additionally, cardiac function indicators, mitochondrial state 3 respiratory rate, respiratory control ratio (RCR), cytochrome C oxidase (C c O), NADH oxidase (NADHO), and succinate oxidase (SUCO) activities, mitochondrial ROS production rate, and mitochondrial ultrastructure were significantly better than those in the I/R group. However, these advantages were completely reversed by the HIF-1α specific inhibitor 2ME2 ( P <0.05). The myocardial protective function of SPostC might be associated with the improvement of mitochondrial respiratory function after up-regulation of HIF-1α expression.

Modulation of Neutrophil Extracellular Trap and Reactive Oxygen Species Release by Periodontal Bacteria

PubMed Central

White, Phillipa C.; Milward, Michael R.; Cooper, Paul R.

2017-01-01

ABSTRACT Oral bacteria are the main trigger for the development of periodontitis, and some species are known to modulate neutrophil function. This study aimed to explore the release of neutrophil extracellular traps (NETs), associated antimicrobial proteins, and reactive oxygen species (ROS) in response to periodontal bacteria, as well as the underlying pathways. Isolated peripheral blood neutrophils were stimulated with 19 periodontal bacteria. NET and ROS release, as well as the expression of NET-bound antimicrobial proteins, elastase, myeloperoxidase, and cathepsin G, in response to these species was measured using fluorescence-based assays. NET and ROS release was monitored after the addition of NADP (NADPH) oxidase pathway modulators and inhibitors of Toll-like receptors (TLRs). Moreover, bacterial entrapment by NETs was visualized microscopically, and bacterial killing was assessed by bacterial culture. Certain microorganisms, e.g., Veillonella parvula and Streptococcus gordonii, stimulated higher levels of ROS and NET release than others. NETs were found to entrap, but not kill, all periodontal bacteria tested. NADPH oxidase pathway modulators decreased ROS production but not NET production in response to the bacteria. Interestingly, TLR inhibitors did not impact ROS and NET release. These data suggest that the variability in the neutrophil response toward different bacteria may contribute to the pathogenesis of periodontal diseases by mechanisms such as bacterial avoidance of host responses and activation of neutrophils. Moreover, our results indicate that bacterium-stimulated NET release may arise in part via NADPH oxidase-independent mechanisms. The role of TLR signaling in bacterium-induced ROS and NET release needs to be further elucidated. PMID:28947649

Modulation of Neutrophil Extracellular Trap and Reactive Oxygen Species Release by Periodontal Bacteria.

PubMed

Hirschfeld, Josefine; White, Phillipa C; Milward, Michael R; Cooper, Paul R; Chapple, Iain L C

2017-12-01

Oral bacteria are the main trigger for the development of periodontitis, and some species are known to modulate neutrophil function. This study aimed to explore the release of neutrophil extracellular traps (NETs), associated antimicrobial proteins, and reactive oxygen species (ROS) in response to periodontal bacteria, as well as the underlying pathways. Isolated peripheral blood neutrophils were stimulated with 19 periodontal bacteria. NET and ROS release, as well as the expression of NET-bound antimicrobial proteins, elastase, myeloperoxidase, and cathepsin G, in response to these species was measured using fluorescence-based assays. NET and ROS release was monitored after the addition of NADP (NADPH) oxidase pathway modulators and inhibitors of Toll-like receptors (TLRs). Moreover, bacterial entrapment by NETs was visualized microscopically, and bacterial killing was assessed by bacterial culture. Certain microorganisms, e.g., Veillonella parvula and Streptococcus gordonii , stimulated higher levels of ROS and NET release than others. NETs were found to entrap, but not kill, all periodontal bacteria tested. NADPH oxidase pathway modulators decreased ROS production but not NET production in response to the bacteria. Interestingly, TLR inhibitors did not impact ROS and NET release. These data suggest that the variability in the neutrophil response toward different bacteria may contribute to the pathogenesis of periodontal diseases by mechanisms such as bacterial avoidance of host responses and activation of neutrophils. Moreover, our results indicate that bacterium-stimulated NET release may arise in part via NADPH oxidase-independent mechanisms. The role of TLR signaling in bacterium-induced ROS and NET release needs to be further elucidated. Copyright © 2017 American Society for Microbiology.

Hyperglycaemia promotes human brain microvascular endothelial cell apoptosis via induction of protein kinase C-ßI and prooxidant enzyme NADPH oxidase

PubMed Central

Shao, Beili; Bayraktutan, Ulvi

2014-01-01

Blood–brain barrier disruption represents a key feature in hyperglycaemia-aggravated cerebral damage after an ischaemic stroke. Although the underlying mechanisms remain largely unknown, activation of protein kinase C (PKC) is thought to play a critical role. This study examined whether apoptosis of human brain microvascular endothelial cells (HBMEC) might contribute to hyperglycaemia-evoked barrier damage and assessed the specific role of PKC in this phenomenon. Treatments with hyperglycaemia (25 mM) or phorbol myristate acetate (PMA, a protein kinase C activator, 100 nM) significantly increased NADPH oxidase activity, O2•- generation, proapoptotic protein Bax expression, TUNEL-positive staining and caspase-3/7 activities. Pharmacological inhibition of NADPH oxidase, PKC-a, PKC-ß or PKC-ßI via their specific inhibitors and neutralisation of O2•- by a cell-permeable superoxide dismutase mimetic, MnTBAP normalised all the aforementioned increases induced by hyperglycaemia. Suppression of these PKC isoforms also negated the stimulatory effects of hyperglycaemia on the protein expression of NADPH oxidase membrane-bound components, Nox2 and p22-phox which determine the overall enzymatic activity. Silencing of PKC-ßI gene through use of specific siRNAs abolished the effects of both hyperglycaemia and PMA on endothelial cell NADPH oxidase activity, O2•- production and apoptosis and consequently improved the integrity and function of an in vitro model of human cerebral barrier comprising HBMEC, astrocytes and pericytes. Hyperglycaemia-mediated apoptosis of HBMEC contributes to cerebral barrier dysfunction and is modulated by sequential activations of PKC-ßI and NADPH oxidase. PMID:24936444

NADPH Oxidase Inhibition Improves Neurological Outcomes in Surgically-Induced Brain Injury

PubMed Central

Lo, Wendy; Bravo, Thomas; Jadhav, Vikram; Zhang, John H.; Tang, Jiping

2007-01-01

Neurosurgical procedures can result in brain injury by various means including direct trauma, hemorrhage, retractor stretch, and electrocautery. This surgically-induced brain injury (SBI) can cause post-operative complications such as brain edema. By creating a mouse model of SBI, we tested whether NADPH oxidase, an important reactive oxygen species producing enzyme, is involved in SBI using transgenic mice lacking gp91phox subunit of NADPH oxidase (gp91phox KO) and apocynin, a specific inhibitor of NADPH oxidase. Neurological function and brain edema were evaluated at 24 hours post-SBI in gp91phox KO and wild-type littermates grouped into SBI and sham-surgery groups. Alternatively, mice were grouped into vehicle- and apocynin-treated (5mg/kg, i.p. 30 minutes before SBI) groups. Oxidative stress indicated by lipid peroxidation (LPO) was measured at 3 and 24 hours post SBI. The gp91phox KO mice, but not the apocynin-treated mice showed significantly improved neurological scores. Brain edema was observed in both gp91phox KO and wild-type groups after SBI; however, there was no significant difference between these two groups. Brain edema was also not affected by apocynin-pretreatment. LPO levels were significantly higher in SBI group in both gp91phox KO and wild-type groups as compared to sham group. A trend, although without statistical significance, was noted towards attenuation of LPO in the gp91phox KO animals as compared to wild-type group. LPO levels were significantly attenuated at 3 hours post-SBI by apocynin pretreatment but not at 24 hours post-SBI. These results suggest that chronic and acute inhibition of NADPH oxidase activity does not reduce brain edema after SBI. Long-term inhibition of NADPH oxidase, however improves neurological functions after SBI. PMID:17317004

Dual functional cholinesterase and MAO inhibitors for the treatment of Alzheimer's disease: synthesis, pharmacological analysis and molecular modeling of homoisoflavonoid derivatives.

PubMed

Wang, Yali; Sun, Yang; Guo, Yueyan; Wang, Zechen; Huang, Ling; Li, Xingshu

2016-01-01

Because of the complexity of Alzheimer's disease (AD), the multi-target-directed ligand (MTDL) strategy is expected to provide superior effects for the treatment of AD, instead of the classic one-drug-one-target strategy. In this context, we focused on the design, synthesis and evaluation of homoisoflavonoid derivatives as dual acetyl cholinesterase (AChE) and monoamine oxidase (MAO-B) inhibitors. Among all the synthesized compounds, compound 10 provided a desired balance of AChE and hMAO-B inhibition activities, with IC50 value of 3.94 and 3.44 μM, respectively. Further studies revealed that compound 10 was a mixed-type inhibitor of AChE and an irreversible inhibitor of hMAO-B, which was also confirmed by molecular modeling studies. Taken together, the data indicated that 10 was a promising dual functional agent for the treatment of AD.

Relationship between the enzymatic browning and phenylalanine ammonia-lyase activity of cut lettuce, and the prevention of browning by inhibitors of polyphenol biosynthesis.

PubMed

Hisaminato, H; Murata, M; Homma, S

2001-05-01

Cut lettuce stored at 4 degrees C gradually turned brown on the cut section after several days of storage. Three factors for enzymatic browning, the polyphenol content, polyphenol oxidase activity, and phenylalanine ammonia-lyase (PAL) activity, were examined during the cold storage of cut lettuce. A relationship between the browning and PAL activity was apparent. We tried to prevent this browning by using the two enzyme inhibitors, 2-aminoindane-2-phosphonic acid (AIP), an inhibitor of the phenylpropanoid pathway, and glyphosate, an inhibitor of the shikimate pathway. AIP and glyphosate significantly inhibited the browning of cut lettuce. The polyphenol content and PAL activity were both reduced by the treatment with AIP. These results show that regulating the biosynthesis of polyphenols is essential to prevent the browning of cut lettuce.

Trimethyltin-Induced Microglial Activation via NADPH Oxidase and MAPKs Pathway in BV-2 Microglial Cells.

PubMed

Kim, Da Jung; Kim, Yong Sik

2015-01-01

Trimethyltin (TMT) is known as a potent neurotoxicant that causes neuronal cell death and neuroinflammation, particularly in the hippocampus. Microglial activation is one of the prominent pathological features of TMT neurotoxicity. Nevertheless, it remains unclear how microglial activation occurs in TMT intoxication. In this study, we aimed to investigate the signaling pathways in TMT-induced microglial activation using BV-2 murine microglial cells. Our results revealed that TMT generates reactive oxygen species (ROS) and increases the expression of CD11b and nuclear factor-κB- (NF-κB-) mediated nitric oxide (NO) and tumor necrosis factor- (TNF-) α in BV-2 cells. We also observed that NF-κB activation was controlled by p38 and JNK phosphorylation. Moreover, TMT-induced ROS generation occurred via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in BV-2 cells. Interestingly, treatment with the NADPH oxidase inhibitor apocynin significantly suppressed p38 and JNK phosphorylation and NF-κB activation and ultimately the production of proinflammatory mediators upon TMT exposure. These findings indicate that NADPH oxidase-dependent ROS generation activated p38 and JNK mitogen-activated protein kinases (MAPKs), which then stimulated NF-κB to release proinflammatory mediators in the TMT-treated BV-2 cells.

Trimethyltin-Induced Microglial Activation via NADPH Oxidase and MAPKs Pathway in BV-2 Microglial Cells

PubMed Central

Kim, Da Jung; Kim, Yong Sik

2015-01-01

Trimethyltin (TMT) is known as a potent neurotoxicant that causes neuronal cell death and neuroinflammation, particularly in the hippocampus. Microglial activation is one of the prominent pathological features of TMT neurotoxicity. Nevertheless, it remains unclear how microglial activation occurs in TMT intoxication. In this study, we aimed to investigate the signaling pathways in TMT-induced microglial activation using BV-2 murine microglial cells. Our results revealed that TMT generates reactive oxygen species (ROS) and increases the expression of CD11b and nuclear factor-κB- (NF-κB-) mediated nitric oxide (NO) and tumor necrosis factor- (TNF-) α in BV-2 cells. We also observed that NF-κB activation was controlled by p38 and JNK phosphorylation. Moreover, TMT-induced ROS generation occurred via nicotinamide adenine dinucleotide phosphate (NADPH) oxidase in BV-2 cells. Interestingly, treatment with the NADPH oxidase inhibitor apocynin significantly suppressed p38 and JNK phosphorylation and NF-κB activation and ultimately the production of proinflammatory mediators upon TMT exposure. These findings indicate that NADPH oxidase-dependent ROS generation activated p38 and JNK mitogen-activated protein kinases (MAPKs), which then stimulated NF-κB to release proinflammatory mediators in the TMT-treated BV-2 cells. PMID:26221064

The role of brassinosteroids in the regulation of the plasma membrane H+-ATPase and NADPH oxidase under cadmium stress.

PubMed

Jakubowska, Dagmara; Janicka, Małgorzata

2017-11-01

The present research aim was to define the role of brassinosteroids (BRs) in plant adaptation to cadmium stress. We observed a stimulating effect of exogenous BR on the activity of two plasma membrane enzymes which play a key role in plants adaptation to cadmium stress, H + -ATPase (EC 3.6.3.14) and NADPH oxidase (EC 1.6.3.1). Using anti-phosphothreonine antibody we showed that modification of PM H + -ATPase activity under BR action could result from phosphorylation of the enzyme protein. Also the relative expression of genes encoding both PM H + -ATPase and NADPH oxidase was affected by BR. To confirm the role of BR in the cadmium stimulating effect on activity of both studied plasma membrane enzymes, an assay in the presence of a BR biosynthesis inhibitor (propiconazole) was performed. Moreover, as a tool in our work we used commercially available plant mutants unable to BR biosynthesis or with dysfunctional BR signaling pathway, to further confirm participation of BR in plant adaptation to heavy metal stress. Presented results demonstrate some elements of the brassinosteroid-induced pathway activated under cadmium stress, wherein H + -ATPase and NADPH oxidase are key factors. Copyright © 2017 Elsevier B.V. All rights reserved.

Monoamine oxidase-B inhibitors in the treatment of Parkinson's disease: clinical-pharmacological aspects.

PubMed

Riederer, Peter; Müller, Thomas

2018-03-22

This invited narrative review emphasizes the role of MAO-B inhibition in the drug portfolio for dopamine substitution in patients with Parkinson's disease. Neuronal and glial MAO-B inhibition contributes to more stable levels of dopamine and other biogenic amines in the synaptic cleft. Accordingly, symptomatic effects of MAO-B inhibition for a limited amelioration of impaired motor behaviour and wearing-off phenomena in patients with Parkinson's disease are well proven, even when MAO-B inhibitors are only applied together with dopamine agonists. Delay of disease progression by MAO-B inhibition is under debate despite positive experimental findings. This discussion does not consider, that levodopa, respectively, dopamine agonists, are substrates, respectively, inhibitors of the ABCB1 (P-gp, MDR1, and CD243) transporter system. It supports toxin efflux over the blood-brain barrier. ABCB1 transporters have a limited capacity. MAO-B inhibitors do not weaken it. Treatment with MAO-B inhibitors is advantageous as it enables sparing of dopamine agonist and levodopa dosing.

N1-Nonyl-1,4-diaminobutane ameliorates brain infarction size in photochemically induced thrombosis model mice.

PubMed

Masuko, Takashi; Takao, Koichi; Samejima, Keijiro; Shirahata, Akira; Igarashi, Kazuei; Casero, Robert A; Kizawa, Yasuo; Sugita, Yoshiaki

2018-04-13

Inhibitors for polyamine oxidizing enzymes, spermine oxidase (SMOX) and N 1 -acetylpolyamine oxidase (PAOX), were designed and evaluated for their effectiveness in a photochemically induced thrombosis (PIT) mouse model. N 1 -Nonyl-1,4-diaminobutane (C9-4) and N 1 -tridecyl-1,4-diaminobutane (C13-4) competitively inhibited the activity of PAOX and SMOX in a manner comparable to N 1 ,N 4 -bis(2,3-butadienyl)-1,4-butanediamine (MDL72527), an irreversible inhibitor of both enzymes. The two compounds were then tested for their effects in the PIT model. Both intraperitoneal (i.p.) and intracerebroventricular (i.c.v.) administration of C9-4 decreased infarct volumes significantly. By contrast, C13-4 reduced the volume of brain infarction by i.c.v. administration, but no reduction was observed after i.p. administration. C9-4 administered by i.p. injection reduced the volume of brain infarction significantly at doses of more than 3 mg/kg, and the dosage of 5 mg/kg or 10 mg/kg demonstrated the most potent effect and were more effective than equivalent doses of the other inhibitors such as MDL72527 and N-benzylhydroxylamine. I.P. injection of 5 mg/kg of C9-4 provided a therapeutic time window of longer than 12 h. This report demonstrates that C9-4 is a potent inhibitor of the polyamine oxidizing enzymes and is useful lead compound for candidate drugs with a long therapeutic time window, to be used in the treatment of ischemic stroke. Copyright © 2018 Elsevier B.V. All rights reserved.

Synthesis of ({sup 11}C) RO 19 6327, a highly selective and reversible monoamine oxidase B inhibitor potentially useful for treatment of Parkinson`s disease

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

Ding, Y.S.; Rehder, K.; Vassello, M.

The potential neuroprotective effect of monoamine oxidase B (MAO B) inhibitors has stimulated intense interest in characterizing their modes of action and in developing new MAO B inhibitor drugs with different properties for clinical investigation in Parkinson`s disease and other enurodegenerative diseases. One of these drugs is Ro 19 6327 (N-(2-aminoethyl)-5-chloro-2-pyridine carboxamide {center_dot}HCl). Ro 19 6327 differs from the suicide inhibitor L-deprenyl in that it is more specific, greater than twenty times as potent in inhibiting MAO B, has no amphetamine metabolites, and is reversible. The recovery of MAO B activity 36 hours after Ro19 6327 treatment discontinuation is relevantmore » in clinical studies since treatment can be withdrawn and changed without the complication of long term effects, as is seen with L-deprenyl. We report here a new synthetic approach to the precursor for Ro 19 6327 suitable for subsequent C-11 labeling for PET studies. Homolytic amidation of 3-chloropyridine afforded 5-chlor-2-pyridinecarboxamide which upon treatment with formaldehyde yielded 5-chlor-N-(hydroxymethyl)-2-pyridinecarboxamide. Conversion to the corresponding acetate afforded a substrate for the displacement reaction with ({sup 11}C) cyanide. Finding a highly selective reducing reagent for the following reduction step was crucial due t;o the presence of four reducible functional groups within the molecule, namely chlorine, pyridine ring, amide, and nitrile. Sodium borohydride in the presence of aluminum chloride was by far the most effective reagent. The final product was then purified by HPLC. The pharmacokinetics, regional distribution and metabolism of ({sup 11}C)Ro 19 6317 are currently under investigation with PET.« less

The monoamine oxidase inhibition properties of selected structural analogues of methylene blue.

PubMed

Delport, Anzelle; Harvey, Brian H; Petzer, Anél; Petzer, Jacobus P

2017-06-15

The thionine dye, methylene blue (MB), is a potent inhibitor of monoamine oxidase (MAO) A, a property that may, at least in part, mediate its antidepressant effects in humans and animals. The central inhibition of MAO-A by MB has also been linked to serotonin toxicity (ST) which may arise when MB is used in combination with serotonergic drugs. Structural analogues and the principal metabolite of MB, azure B, have also been reported to inhibit the MAO enzymes, with all compounds exhibiting specificity for the MAO-A isoform. To expand on the structure-activity relationships (SARs) of MAO inhibition by MB analogues, the present study investigates the human MAO inhibition properties of five MB analogues: neutral red, Nile blue, new methylene blue, cresyl violet and 1,9-dimethyl methylene blue. Similar to MB, these analogues also are specific MAO-A inhibitors with cresyl violet (IC 50 =0.0037μM), Nile blue (IC 50 =0.0077μM) and 1,9-dimethyl methylene blue (IC 50 =0.018μM) exhibiting higher potency inhibition compared to MB (IC 50 =0.07μM). Nile blue also represents a potent MAO-B inhibitor with an IC 50 value of 0.012μM. From the results it may be concluded that non-thionine MB analogues (e.g. cresyl violet and Nile blue) also may exhibit potent MAO inhibition, a property which should be considered when using these compounds in pharmacological studies. Benzophenoxazines such as cresyl violet and Nile blue are, similar to phenothiazines (e.g. MB), representative of high potency MAO-A inhibitors with a potential risk of ST. Copyright © 2017 Elsevier Inc. All rights reserved.

In vitro monoamine oxidase inhibition potential of alpha-methyltryptamine analog new psychoactive substances for assessing possible toxic risks.

PubMed

Wagmann, Lea; Brandt, Simon D; Kavanagh, Pierce V; Maurer, Hans H; Meyer, Markus R

2017-04-15

Tryptamines have emerged as new psychoactive substances (NPS), which are distributed and consumed recreationally without preclinical studies or safety tests. Within the alpha-methylated tryptamines, some of the psychoactive effects of the prototypical alpha-methyltryptamine (AMT) have been described decades ago and a contributing factor of its acute toxicity appears to involve the inhibition of monoamine oxidase (MAO). However, detailed information about analogs is scarce. Therefore, thirteen AMT analogs were investigated for their potential to inhibit MAO. An in vitro assay analyzed using hydrophilic interaction liquid chromatography-high resolution-tandem mass spectrometry was developed and validated. The AMT analogs were incubated with recombinant human MAO-A or B and kynuramine, a non-selective MAO substrate to determine the IC 50 values. The known MAO-A inhibitors 5-(2-aminopropyl)indole (5-IT), harmine, harmaline, yohimbine, and the MAO-B inhibitor selegiline were tested for comparison. AMT and all analogs showed MAO-A inhibition properties with IC 50 values between 0.049 and 166μM, whereas four analogs inhibited also MAO-B with IC 50 values between 82 and 376μM. 7-Me-AMT provided the lowest IC 50 value against MAO-A comparable to harmine and harmaline and was identified as a competitive MAO-A inhibitor. Furthermore, AMT, 7-Me-AMT, and nine further analogs inhibited MAO activity in human hepatic S9 fraction used as model for the human liver which expresses both isoforms. The obtained results suggested that MAO inhibition induced by alpha-methylated tryptamines might be clinically relevant concerning possible serotonergic and adrenergic effects and interactions with drugs (of abuse) particularly acting as monoamine reuptake inhibitors. However, as in vitro assays have only limited conclusiveness, further studies are needed. Copyright © 2017 Elsevier B.V. All rights reserved.

The inhibition of superoxide production in EL4 lymphoma cells overexpressing growth hormone.

PubMed

Arnold, Robyn E; Weigent, Douglas A

2003-05-01

A substantial body of research exists to support the production of growth hormone by cells of the immune system. However, the function and mechanism of action of lymphocyte-derived growth hormone remain largely unelucidated. Since, it has been found that exogenous growth hormone (GH) primes neutrophils for the production of reactive oxygen intermediates (ROI) and in particular superoxide (O2-), we investigated the role of GH on the production of O2- in T cells. Furthermore, we examined whether endogenous and exogenous GH act similarly. Our studies show that overexpression of GH in EL4, a T-cell lymphoma cell line, results in a decrease in the production of O2- compared to control cells, as detected using the fluorescent dye, dihydroethidium. O2- production in control cells was not affected by treatment with inhibitors of xanthine oxidase or a non-specific NADPH-oxidase inhibitor. However, treatment with diallyl sulfide, an inhibitor of cytochrome P450 2E1 mimicked the reduction in O2- production seen in cells overexpressing GH. Although no significant change could be detected in CYP2E1 protein levels, CYP2E1 activity was found to be greater in control EL4 than in cells overexpressing GH. Both the decrease in O2- production and the lower CYP2E1 activity in GH overexpressing cells could be abrogated by treatment with N(G)-monomethyl-L-arginine, an inhibitor of nitric oxide synthase. The overexpression of GH protects cells from apoptosis induced by isoniazid, a CYP2E1 inducer, suggesting a role for nitric oxide as a mediator in the regulation of xenobiotic metabolism and apoptosis-protection by lymphocyte GH.

Lysyl oxidases regulate fibrillar collagen remodelling in idiopathic pulmonary fibrosis.

PubMed

Tjin, Gavin; White, Eric S; Faiz, Alen; Sicard, Delphine; Tschumperlin, Daniel J; Mahar, Annabelle; Kable, Eleanor P W; Burgess, Janette K

2017-11-01

Idiopathic pulmonary fibrosis (IPF) is a progressive scarring disease of the lung with few effective therapeutic options. Structural remodelling of the extracellular matrix [i.e. collagen cross-linking mediated by the lysyl oxidase (LO) family of enzymes (LOX, LOXL1-4)] might contribute to disease pathogenesis and represent a therapeutic target. This study aimed to further our understanding of the mechanisms by which LO inhibitors might improve lung fibrosis. Lung tissues from IPF and non-IPF subjects were examined for collagen structure (second harmonic generation imaging) and LO gene (microarray analysis) and protein (immunohistochemistry and western blotting) levels. Functional effects (collagen structure and tissue stiffness using atomic force microscopy) of LO inhibitors on collagen remodelling were examined in two models, collagen hydrogels and decellularized human lung matrices. LOXL1 / LOXL2 gene expression and protein levels were increased in IPF versus non-IPF. Increased collagen fibril thickness in IPF versus non-IPF lung tissues correlated with increased LOXL1/LOXL2, and decreased LOX, protein expression. β-Aminoproprionitrile (β-APN; pan-LO inhibitor) but not Compound A (LOXL2-specific inhibitor) interfered with transforming growth factor-β-induced collagen remodelling in both models. The β-APN treatment group was tested further, and β-APN was found to interfere with stiffening in the decellularized matrix model. LOXL1 activity might drive collagen remodelling in IPF lungs. The interrelationship between collagen structural remodelling and LOs is disrupted in IPF lungs. Inhibition of LO activity alleviates fibrosis by limiting fibrillar collagen cross-linking, thereby potentially impeding the formation of a pathological microenvironment in IPF. © 2017. Published by The Company of Biologists Ltd.

Mechanisms underlying sodium nitroprusside-induced tolerance in the mouse aorta: Role of ROS and cyclooxygenase-derived prostanoids.

PubMed

Diniz, Mariana C; Olivon, Vania C; Tavares, Lívia D; Simplicio, Janaina A; Gonzaga, Natália A; de Souza, Daniele G; Bendhack, Lusiane M; Tirapelli, Carlos R; Bonaventura, Daniella

2017-05-01

To determine the role of reactive oxygen species (ROS) on sodium nitroprusside (SNP)-induced tolerance. Additionally, we evaluated the role of ROS on NF-κB activation and pro-inflammatory cytokines production during SNP-induced tolerance. To induce in vitro tolerance, endothelium-intact or -denuded aortic rings isolated from male Balb-c mice were incubated for 15, 30, 45 or 60min with SNP (10nmol/L). Tolerance to SNP was observed after incubation of endothelium-denuded, but not endothelium-intact aortas for 60min with this inorganic nitrate. Pre-incubation of denuded rings with tiron (superoxide anion (O 2 - ) scavenger), and the NADPH oxidase inhibitors apocynin and atorvastatin reversed SNP-induced tolerance. l-NAME (non-selective NOS inhibitor) and l-arginine (NOS substrate) also prevented SNP-induced tolerance. Similarly, ibuprofen (non-selective cyclooxygenase (COX) inhibitor), nimesulide (selective COX-2 inhibitor), AH6809 (prostaglandin PGF 2 α receptor antagonist) or SQ29584 [PGH 2 /thromboxane TXA 2 receptor antagonist] reversed SNP-induced tolerance. Increased ROS generation was detected in tolerant arteries and both tiron and atorvastatin reversed this response. Tiron prevented tolerance-induced increase on O 2 - and hydrogen peroxide (H 2 O 2 ) levels. The increase onp65/NF-κB expression and TNF-α production in tolerant arteries was prevented by tiron. The major new finding of our study is that SNP-induced tolerance is mediated by NADPH-oxidase derived ROS and vasoconstrictor prostanoids derived from COX-2, which are capable of reducing the vasorelaxation induced by SNP. Additionally, we found that ROS mediate the activation of NF-κB and the production of TNF-α in tolerant arteries. These findings identify putative molecular mechanisms whereby SNP induces tolerance in the vasculature. Copyright © 2017 Elsevier Inc. All rights reserved.

Mediated effect of ultrasound treated Diclofenac on mussel hemocytes: First evidence for the involvement of respiratory burst enzymes in the induction of DCF-mediated unspecific mode of action.

PubMed

Toufexi, Eirini; Dailianis, Stefanos; Vlastos, Dimitris; Manariotis, Ioannis D

2016-06-01

The present study investigates the toxic behavior of diclofenac (DCF) before and after its ultrasound (US) treatment, as well as the involvement of intracellular target molecules, such as NADPH oxidase and NO synthase, in the DCF-induced adverse effects on hemocytes of mussel Mytilus galloprovincialis. In this context, appropriate volumes (350 and 500mL) of DCF solutions (at concentrations of 2, 2.5, 5 and 10mgL(-1)) were treated under different ultrasound operating conditions (frequency at 582 and 862kHz, electric power density at 133 and 167W) for assessing US method efficiency. In parallel, DCF and US DCF-mediated cytotoxic (in terms of cell viability measured with the use of neutral red uptake/NRU method), oxidative (in terms of superoxide anions/(.)O2(-), nitric oxides such as NO2(-) and lipid peroxidation products, such as malondialdehyde/MDA content) and genotoxic (DNA damage measured by the use of Comet assay method) effects were investigated in hemocytes exposed for 1h to 5, 10 and 100ngL(-1) and 1, 10 and 20μgL(-1) of DCF. The involvement of NADPH oxidase and NO synthase to the DCF-induced toxicity was further investigated by the use of 10μΜ L-NAME, a NO synthase inhibitor and 10μΜ DPI, a NADPH oxidase inhibitor. According to the results, 350mL of 2mgL(-1) DCF showed higher degradation (>50%) under 167W electric power density and frequency at 862kHz for 120min, compared to degradation in all other cases, followed by a significant elimination of its toxicity. Specifically, US DCF-treated hemocytes showed a significant attenuation of DCF-mediated cytotoxic, oxidative and genotoxic effects, which appeared to be caused by NADPH oxidase and NO synthase activation, since their inhibition was followed by a significant elimination of (.)O2(-) and NO2(-) generation and the concomitant oxidative damage within cells. The results of the present study showed for the first time that unspecific mode of action of DCF, associated with the induction of NADPH oxidase and NO synthase in mussel hemocytes, could be significantly diminished after partial US degradation of DCF, at least under optimized operating conditions currently tested. Copyright © 2016 Elsevier B.V. All rights reserved.

A novel domain of amino-Nogo-A protects HT22 cells exposed to oxygen glucose deprivation by inhibiting NADPH oxidase activity.

PubMed

Guo, Fan; Wang, Huiwen; Li, Liya; Zhou, Heng; Wei, Haidong; Jin, Weilin; Wang, Qiang; Xiong, Lize

2013-04-01

This study aimed to investigate the protective effect of the M9 region (residues 290-562) of amino-Nogo-A fused to the human immunodeficiency virus trans-activator TAT in an in vitro model of ischemia-reperfusion induced by oxygen-glucose deprivation (OGD) in HT22 hippocampal neurons, and to investigate the role of NADPH oxidase in this protection. Transduction of TAT-M9 was analyzed by immunofluorescence staining and western blot. The biologic activity of TAT-M9 was assessed by its effects against OGD-induced HT22 cell damage, compared with a mutant M9 fusion protein or vehicle. Cellular viability and lactate dehydrogenase (LDH) release were assessed. Neuronal apoptosis was evaluated by flow cytometry. The Bax/Bcl-2 ratio was determined by western blotting. Reactive oxygen species (ROS) levels and NADPH oxidase activity were also measured in the presence or absence of an inhibitor or activator of NADPH oxidase. Our results confirmed the delivery of the protein into HT22 cells by immunofluorescence and western blot. Addition of 0.4 μmol/L TAT-M9 to the culture medium effectively improved neuronal cell viability and reduced LDH release induced by OGD. The fusion protein also protected HT22 cells from apoptosis, suppressed overexpression of Bax, and inhibited the reduction in Bcl-2 expression. Furthermore, TAT-M9, as well as apocynin, decreased NADPH oxidase activity and ROS content. The protective effects of the TAT-M9 were reversed by TBCA, an agonist of NADPH oxidase. In conclusion, TAT-M9 could be successfully transduced into HT22 cells, and protected HT22 cells against OGD damage by inhibiting NADPH oxidase-mediated oxidative stress. These findings suggest that the TAT-M9 protein may be an efficient therapeutic agent for neuroprotection.

Freezing of Gait in Parkinsonism and its Potential Drug Treatment.

PubMed

Zhang, Li-Li; Canning, S Duff; Wang, Xiao-Ping

2016-01-01

Freezing of gait (FOG) is a heterogeneous symptom. Studies of treatment for FOG are scarce. Levodopa and monoamine oxidase inhibitors (rasagiline and selegiline) have shown effective improvement for FOG. Other drugs, such as L-threo-3, 4-dihydroxyphenylserine, amantadine, and botulinum toxin have exhibited some beneficial effects. The present review summarizes the potential drug treatment for FOG in Parkinsonism.

Freezing of Gait in Parkinsonism and its Potential Drug Treatment

PubMed Central

Zhang, Li-Li; Canning, S. Duff; Wang, Xiao-Ping

2016-01-01

Freezing of gait (FOG) is a heterogeneous symptom. Studies of treatment for FOG are scarce. Levodopa and monoamine oxidase inhibitors (rasagiline and selegiline) have shown effective improvement for FOG. Other drugs, such as L-threo-3, 4-dihydroxyphenylserine, amantadine, and botulinum toxin have exhibited some beneficial effects. The present review summarizes the potential drug treatment for FOG in Parkinsonism. PMID:26635194

Monoamine oxidase: Radiotracer chemistry and human studies

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

Fowler, Joanna S.; Logan, Jean; Shumay, Elena

Monoamine oxidase (MAO) oxidizes amines from both endogenous and exogenous sources thereby regulating the concentration of neurotransmitter amines such as serot onin, norepinephrine and dopamine as well as many xenobiotics. MAO inhibitor drugs are used in the treatment of Parkinson’s disease and in depression stimulating the development of radiotracer tools to probe the role of MAO in normal human biology and in disease. Over the past 30 since the first radiotracers were developed and the first PET images of MAO in humans were carried out, PET studies of brain MAO in healthy volunteers and in patients have identified different variablesmore » which have contributed to different MAO levels in brain and in peripheral organs. MAO radiotracers and PET have also been used to study the current and developing MAO inhibitor drugs including the selection of doses for clinical trials. In this article, we describe (1) the development of MAO radiotracers; (2) human studies including the relationship of brain MAO levels to genotype, personality, neurological and psychiatric disorders; (3) examples of the use of MAO radiotracers in drug research and development. We will conclude with outstanding needs to improve the radiotracers which are currently used and possible new applications.« less

A small molecule polyamine oxidase inhibitor blocks androgen-induced oxidative stress and delays prostate cancer progression in the transgenic adenocarcinoma of the mouse prostate model.

PubMed

Basu, Hirak S; Thompson, Todd A; Church, Dawn R; Clower, Cynthia C; Mehraein-Ghomi, Farideh; Amlong, Corey A; Martin, Christopher T; Woster, Patrick M; Lindstrom, Mary J; Wilding, George

2009-10-01

High levels of reactive oxygen species (ROS) present in human prostate epithelia are an important etiologic factor in prostate cancer (CaP) occurrence, recurrence, and progression. Androgen induces ROS production in the prostate by a yet unknown mechanism. Here, to the best of our knowledge, we report for the first time that androgen induces an overexpression of spermidine/spermine N1-acetyltransferase, the rate-limiting enzyme in the polyamine oxidation pathway. As prostatic epithelia produce a large excess of polyamines, the androgen-induced polyamine oxidation that produces H2O2 could be a major reason for the high ROS levels in the prostate epithelia. A small molecule polyamine oxidase inhibitor N,N'-butanedienyl butanediamine (MDL 72,527 or CPC-200) effectively blocks androgen-induced ROS production in human CaP cells, as well as significantly delays CaP progression and death in animals developing spontaneous CaP. These data show that polyamine oxidation is not only a major pathway for ROS production in prostate, but inhibiting this pathway also successfully delays CaP progression.

DL-3-n-butylphthalide-Edaravone hybrids as novel dual inhibitors of amyloid-β aggregation and monoamine oxidases with high antioxidant potency for Alzheimer's therapy.

PubMed

Qiang, Xiaoming; Li, Yan; Yang, Xia; Luo, Li; Xu, Rui; Zheng, Yunxiaozhu; Cao, Zhongcheng; Tan, Zhenghuai; Deng, Yong

2017-02-15

Considering the complex etiology of Alzheimer's disease (AD), multifunctional agents may be beneficial for the treatment of this disease. A series of DL-3-n-butylphthalide-Edaravone hybrids were designed, synthesized and evaluated as novel dual inhibitors of amyloid-β aggregation and monoamine oxidases. Among them, compounds 9a-d exhibited good inhibition of self-induced Aβ 1-42 aggregation with inhibition ratio 57.7-71.5%. For MAO, these new hybrids exhibited good balance of inhibition for MAO-A and MAO-B. In addition, all target compounds retained the antioxidant activity of edaravone, showed equal or better antioxidant activity than edaravone. The results of the parallel artificial membrane permeability assay for blood-brain barrier indicated that compounds 9a-d would be able to cross the blood-brain barrier and reach their biological targets in the central nervous system. The promising results in all assays demonstrated that the strategy behind the designing of compounds was rational and favourable. Taken together, these preliminary findings suggested that the compounds with the strongest bioactivity deserves further investigated for pharmacological development in AD therapy. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of iodinated contrast media on the activities of histamine inactivating enzymes diamine oxidase and histamine N-methyltransferase in vitro.

PubMed

Kuefner, M A; Feurle, J; Petersen, J; Uder, M; Schwelberger, H G

2014-01-01

Iodinated contrast media can cause pseudoallergic reactions associated with histamine release in significant numbers of patients. To clarify whether these adverse reactions may be aggravated by a compromised histamine catabolism we asked if radiographic contrast agents in vitro inhibit the histamine inactivating enzymes diamine oxidase (DAO) and histamine N-methyltransferase (HMT). Nine iodinated contrast agents were tested in vitro. Following pre-incubation of purified porcine kidney DAO and recombinant human HMT with 0.1-10mM of the respective contrast medium (H2O and specific inhibitors of DAO and HMT as controls) enzyme activities were determined by using radiometric micro assays. None of the contrast media irrespective of their structure showed significant inhibition of the activities of DAO and HMT. Pre-incubation of the enzymes with specific inhibitors led to complete inhibition of the respective enzymatic activity. The iodinated contrast media tested in vitro did not exhibit inhibition of histamine converting enzymes at physiologically relevant concentrations. However due to the in vitro character of this study these results do not directly reflect the in vivo situation. Copyright © 2012 SEICAP. Published by Elsevier Espana. All rights reserved.

Monoamine oxidase: Radiotracer chemistry and human studies

DOE PAGES

Fowler, Joanna S.; Logan, Jean; Shumay, Elena; ...

2015-03-01

Monoamine oxidase (MAO) oxidizes amines from both endogenous and exogenous sources thereby regulating the concentration of neurotransmitter amines such as serot onin, norepinephrine and dopamine as well as many xenobiotics. MAO inhibitor drugs are used in the treatment of Parkinson’s disease and in depression stimulating the development of radiotracer tools to probe the role of MAO in normal human biology and in disease. Over the past 30 since the first radiotracers were developed and the first PET images of MAO in humans were carried out, PET studies of brain MAO in healthy volunteers and in patients have identified different variablesmore » which have contributed to different MAO levels in brain and in peripheral organs. MAO radiotracers and PET have also been used to study the current and developing MAO inhibitor drugs including the selection of doses for clinical trials. In this article, we describe (1) the development of MAO radiotracers; (2) human studies including the relationship of brain MAO levels to genotype, personality, neurological and psychiatric disorders; (3) examples of the use of MAO radiotracers in drug research and development. We will conclude with outstanding needs to improve the radiotracers which are currently used and possible new applications.« less

Hydroxylated chalcones with dual properties: xanthine oxidase inhibitors and radical scavengers

PubMed Central

Hofmann, Emily; Webster, Jonathan; Do, Thuy; Kline, Reid; Snider, Lindsey; Hauser, Quintin; Higginbottom, Grace; Campbell, Austin; Ma, Lili; Paula, Stefan

2016-01-01

In this study, we evaluated the abilities of a series of chalcones to inhibit the activity of the enzyme xanthine oxidase (XO) and to scavenge radicals. 20 mono- and polyhydroxylated chalcone derivatives were synthesized by Claisen-Schmidt condensation reactions and then tested for inhibitory potency against XO, a known generator of reactive oxygen species (ROS). In parallel, the ability of the synthesized chalcones to scavenge a stable radical was determined. Structure-activity relationship analysis in conjunction with molecular docking indicated that the most active XO inhibitors carried a minimum of three hydroxyl groups. Moreover, the most effective radical scavengers had two neighboring hydroxyl groups on at least one of the two phenyl rings. Since it has been proposed previously that XO inhibition and radical scavenging could be useful properties for reduction of ROS-levels in tissue, we determined the chalcones’ effects to rescue neurons subjected to ROS-induced stress created by the addition of β-amyloid peptide. Best protection was provided by chalcones that combined good inhibitory potency with high radical scavenging ability in a single molecule, an observation that points to a potential therapeutic value of this compound class. PMID:26762836

Functional mechanism of neuroprotection by inhibitors of type B monoamine oxidase in Parkinson's disease.

PubMed

Naoi, Makoto; Maruyama, Wakako

2009-08-01

Neuroprotective therapy has been proposed for age-related neurodegenerative disorders, including Parkinson's disease. Inhibitors of type B monoamine oxidase (MAOB-Is), rasagiline and (-)deprenyl, are the most promising candidate neuroprotective drugs. Clinical trials of rasagiline in patients with Parkinson's disease suggest that rasagiline may have some disease-modifying effects. Results using animal and cellular models have proved that the MAOB-Is protect neurons by the intervention of 'intrinsic' mitochondrial apoptotic cascade and the induction of prosurvival antiapoptotic Bcl-2 and neurotrophic factors. Rasagiline-related MAOB-Is prevent mitochondrial permeability transition induced by various insults and activation of subsequent apoptotic cascades: cytochrome c release, casapase activation, and condensation and fragmentation of nuclear DNA. MAOB-Is increase transcription of prosurvival genes through activating the nuclear transcription factor-(NF) system. Rasagiline increases the protein and mRNA levels of GDNF in dopaminergic SH-SY5Y cells, whereas (-)deprenyl increases those of BDNF. Systemic administration of (-)deprenyl and rasagiline increases these neurotrophic factors in the cerebrospinal fluid from patients with Parkinson's disease and nonhuman primates. This review presents recent advances in our understanding of the neuroprotection offered by MAOB-Is and possible evaluation of neuroprotective efficacy in clinical samples is discussed.

Chemical mechanism of D-amino acid oxidase from Rhodotorula gracilis: pH dependence of kinetic parameters.

PubMed Central

Ramón, F; Castillón, M; De La Mata, I; Acebal, C

1998-01-01

The variation of kinetic parameters of d-amino acid oxidase from Rhodotorula gracilis with pH was used to gain information about the chemical mechanism of the oxidation of D-amino acids catalysed by this flavoenzyme. d-Alanine was the substrate used. The pH dependence of Vmax and Vmax/Km for alanine as substrate showed that a group with a pK value of 6.26-7.95 (pK1) must be unprotonated and a group with a pK of 10.8-9.90 (pK2) must be protonated for activity. The lower pK value corresponded to a group on the enzyme involved in catalysis and whose protonation state was not important for binding. The higher pK value was assumed to be the amino group of the substrate. Profiles of pKi for D-aspartate as competitive inhibitor showed that binding is prevented when a group on the enzyme with a pK value of 8.4 becomes unprotonated; this basic group was not detected in Vmax/Km profiles suggesting its involvement in binding of the beta-carboxylic group of the inhibitor. PMID:9461524

Small GTPases and Stress Responses of vvran1 in the Straw Mushroom Volvariella volvacea

PubMed Central

Yan, Jun-Jie; Xie, Bin; Zhang, Lei; Li, Shao-Jie; van Peer, Arend F.; Wu, Ta-Ju; Chen, Bing-Zhi; Xie, Bao-Gui

2016-01-01

Small GTPases play important roles in the growth, development and environmental responses of eukaryotes. Based on the genomic sequence of the straw mushroom Volvariella volvacea, 44 small GTPases were identified. A clustering analysis using human small GTPases as the references revealed that V. volvacea small GTPases can be grouped into five families: nine are in the Ras family, 10 are in the Rho family, 15 are in the Rab family, one is in the Ran family and nine are in the Arf family. The transcription of vvran1 was up-regulated upon hydrogen peroxide (H2O2) stress, and could be repressed by diphenyleneiodonium chloride (DPI), a NADPH oxidase-specific inhibitor. The number of vvran1 transcripts also increased upon cold stress. Diphenyleneiodonium chloride, but not the superoxide dismutase (SOD) inhibitor diethy dithiocarbamate (DDC), could suppress the up-regulation of vvran1 gene expression to cold stress. These results combined with the high correlations between gene expression and superoxide anion (O2−) generation indicated that vvran1 could be one of the candidate genes in the downstream of O2− mediated pathways that are generated by NADPH oxidase under low temperature and oxidative stresses. PMID:27626406

Synthesis and Herbicidal Activity of Pyrido[2,3-d]pyrimidine-2,4-dione-Benzoxazinone Hybrids as Protoporphyrinogen Oxidase Inhibitors.

PubMed

Wang, Da-Wei; Li, Qian; Wen, Kai; Ismail, Ismail; Liu, Dan-Dan; Niu, Cong-Wei; Wen, Xin; Yang, Guang-Fu; Xi, Zhen

2017-07-05

To search for new protoporphyrinogen oxidase (PPO, EC 1.3.3.4) inhibitors with improved bioactivity, a series of novel pyrido[2,3-d]pyrimidine-2,4-dione-benzoxazinone hybrids, 9-13, were designed and synthesized. Several compounds with improved tobacco PPO (mtPPO)-inhibiting and promising herbicidal activities were found. Among them, the most potent compound, 3-(7-fluoro-3-oxo-4-(prop-2-yn-1-yl)-3,4-dihydro-2H-benzo[b][1,4] oxazin-6-yl)-1-methylpyrido[2,3-d]pyrimidine-2,4(1H,3H)-dione, 11q, with a K i value of 0.0074 μM, showed six times more activity than flumioxazin (K i = 0.046 μM) against mtPPO. Compound 11q displayed a strong and broad spectrum of weed control at 37.5-150 g of active ingredient (ai)/ha by both post- and pre-emergence application, which was comparable to that of flumioxazin. 11q was safe to maize, soybean, peanut, and cotton at 150 g ai/ha, and selective to rice and wheat at 75 g ai/ha by pre-emergence application, indicating potential applicability in these fields.

Assessment of Enzyme Inhibition: A Review with Examples from the Development of Monoamine Oxidase and Cholinesterase Inhibitory Drugs.

PubMed

Ramsay, Rona R; Tipton, Keith F

2017-07-15

The actions of many drugs involve enzyme inhibition. This is exemplified by the inhibitors of monoamine oxidases (MAO) and the cholinsterases (ChE) that have been used for several pharmacological purposes. This review describes key principles and approaches for the reliable determination of enzyme activities and inhibition as well as some of the methods that are in current use for such studies with these two enzymes. Their applicability and potential pitfalls arising from their inappropriate use are discussed. Since inhibitor potency is frequently assessed in terms of the quantity necessary to give 50% inhibition (the IC 50 value), the relationships between this and the mode of inhibition is also considered, in terms of the misleading information that it may provide. Incorporation of more than one functionality into the same molecule to give a multi-target-directed ligands (MTDLs) requires careful assessment to ensure that the specific target effects are not significantly altered and that the kinetic behavior remains as favourable with the MTDL as it does with the individual components. Such factors will be considered in terms of recently developed MTDLs that combine MAO and ChE inhibitory functions.

Inhibition of Excessive Monoamine Oxidase A/B Activity Protects Against Stress-induced Neuronal Death in Huntington Disease.

PubMed

Ooi, Jolene; Hayden, Michael R; Pouladi, Mahmoud A

2015-12-01

Monoamine oxidases (MAO) are important components of the homeostatic machinery that maintains the levels of monoamine neurotransmitters, including dopamine, in balance. Given the imbalance in dopamine levels observed in Huntington disease (HD), the aim of this study was to examine MAO activity in a mouse striatal cell model of HD and in human neural cells differentiated from control and HD patient-derived induced pluripotent stem cell (hiPSC) lines. We show that mouse striatal neural cells expressing mutant huntingtin (HTT) exhibit increased MAO expression and activity. We demonstrate using luciferase promoter assays that the increased MAO expression reflects enhanced epigenetic activation in striatal neural cells expressing mutant HTT. Using cellular stress paradigms, we further demonstrate that the increase in MAO activity in mutant striatal neural cells is accompanied by enhanced susceptibility to oxidative stress and impaired viability. Treatment of mutant striatal neural cells with MAO inhibitors ameliorated oxidative stress and improved cellular viability. Finally, we demonstrate that human HD neural cells exhibit increased MAO-A and MAO-B expression and activity. Altogether, this study demonstrates abnormal MAO expression and activity and suggests a potential use for MAO inhibitors in HD.

Tight-Binding Inhibition of Human Monoamine Oxidase B by Chromone Analogs: A Kinetic, Crystallographic, and Biological Analysis.

PubMed

Reis, Joana; Manzella, Nicola; Cagide, Fernando; Mialet-Perez, Jeanne; Uriarte, Eugenio; Parini, Angelo; Borges, Fernanda; Binda, Claudia

2018-05-10

Monoamine oxidase B (MAO-B) is a validated drug target for Parkinson's disease. Chromone derivatives were identified as novel potent and reversible MAO-B inhibitors, and herewith we report on a crystallographic and biochemical analysis to investigate their inhibition mechanism. The crystal structures of human MAO-B in complex with three chromone analogs bearing different substituents on the exocyclic aromatic ring (determined at 1.6-1.8 Å resolution) showed that they all bind in the active site cavity of the protein with the chromone moiety located in front of the FAD cofactor. These inhibitors form two hydrogen bonds with Tyr435 and Cys172 and perfectly fit the hydrophobic flat active site of human MAO-B. This is reflected in their tight-binding mechanism of inhibition with K i values of 55, 17, and 31 nM for N-(3',4'-dimethylphenyl)-4-oxo-4 H-chromene-3-carboxamide (1), N-(3'-chlorophenyl)-4-oxo-4 H-chromene-3-carboxamide (2), and N-(3'-fluorophenyl)-4-oxo-4 H-chromene-3-carboxamide (3), respectively. These compounds were also 1000-fold more effective than l-deprenyl in reducing the cellular levels of reactive oxygen species (ROS).

Knowledge based identification of MAO-B selective inhibitors using pharmacophore and structure based virtual screening models.

PubMed

Boppana, Kiran; Dubey, P K; Jagarlapudi, Sarma A R P; Vadivelan, S; Rambabu, G

2009-09-01

Monoamine Oxidase B interaction with known ligands was investigated using combined pharmacophore and structure based modeling approach. The docking results suggested that the pharmacophore and docking models are in good agreement and are used to identify the selective MAO-B inhibitors. The best model, Hypo2 consists of three pharmacophore features, i.e., one hydrogen bond acceptor, one hydrogen bond donor and one ring aromatic. The Hypo2 model was used to screen an in-house database of 80,000 molecules and have resulted in 5500 compounds. Docking studies were performed, subsequently, on the cluster representatives of 530 hits from 5500 compounds. Based on the structural novelty and selectivity index, we have suggested 15 selective MAO-B inhibitors for further synthesis and pharmacological screening.

Protoporphyrinogen oxidase: high affinity tetrahydrophthalimide radioligand for the inhibitor/herbicide-binding site in mouse liver mitochondria.

PubMed

Birchfield, N B; Casida, J E

1996-01-01

Protoporphyrinogen oxidase (protox), the last common enzyme in heme and chlorophyll biosynthesis, is the target of several classes of herbicides acting as inhibitors in both plants and mammals. N-(4-Chloro-2-fluoro-5-(propargyloxy)phenyl)-3,4,5,6-tetrahydro phthalimide (a potent protox inhibitor referred to as THP) was synthesized as a candidate radioligand ([3H]-THP) by selective catalytic reduction of 3,6-dihydrophthalic anhydride (DHPA) with tritium gas followed by condensation in 45% yield with 4-chloro-2-fluoro-5-(propargyloxy)aniline. Insertion of tritium at the 3 and 6 carbons of DHPA as well as the expected 4 and 5 carbons resulted in high specific activity [3H]THP (92 Ci/mmol). This radioligand undergoes rapid, specific, saturable, and reversible binding to the inhibitor/herbicide binding site of the protox component of cholate-solubilized mouse liver mitochondria with an apparent Kd of 0.41 nM and Bmax of 0.40 pmol/mg of protein. In the standard assay, mouse preparation (150 micrograms of protein) and [3H]THP (0.5 nM) are incubated in 500 microL of phosphate buffer at pH 7.2 for 15 min at 25 degrees C followed by addition of ammonium sulfate and filtration with glass fiber filters. The potencies of five nitrodiphenyl ethers and two other herbicides as inhibitors of [3H]THP binding correlate well with those for inhibition of protox activity (r2 = 0.97, n = 7), thus validating the binding assay as relevant to enzyme inhibition. It is also suitable to determine in vivo block as illustrated by an approximately 50% decrease in [3H]THP binding in liver mitochondria from mice treated ip with oxyfluorfen at 4 mg/kg. This is the first report of a binding assay for protox in mammals. The high affinity and specific activity of [3H]THP facilitate quantitation of protox and therefore research on a sensitive inhibition site for porphyrin biosynthesis.

Competitive binding experiments can reduce the false positive results of affinity-based ultrafiltration-HPLC: A case study for identification of potent xanthine oxidase inhibitors from Perilla frutescens extract.

PubMed

Wang, Zhiqiang; Kwon, Shin Hwa; Hwang, Seung Hwan; Kang, Young-Hee; Lee, Jae-Yong; Lim, Soon Sung

2017-03-24

The purpose of this study was to assess the possibility of using competitive binding experiments with ultrafiltration-HPLC analysis to identify potent xanthine oxidase (XO) inhibitors from the Perilla frutescens extract as an attempt to reduce the number of false positive results. To isolate the enzyme-ligand complex from unbound compounds, the P. frutescens extract was either incubated in the absence of XO, in the presence of XO, or with the active site blocked XO before the ultrafiltration was performed. Allopurinaol was used as the XO active site blocker. The unbound compounds were subjected to HPLC analysis. The degree of total binding (TBD) and degree of specific binding (SBD) of each compound were calculated using the peak areas. TBD represents the binding affinities of compounds from the P. frutescens extract for the XO binding site. SBD represents the XO competitive binding between allopurinol and ligands from the extract samples. Two criteria were applied to select putative targets that could help avoid false positives. These include TBD>30% and SBD>10%. Using that approach, kaempferol-3-O-rutinoside, rosmarinic acid, methyl-rosmarinic acid, apigenin, and 4',5,7-trimethoxyflavone were identified, from total 11 compounds, as potent XO inhibitors. Finally, apigenin, 4',5,7-trimethoxyflavone, and luteolin were XO inhibitors verified through an XO inhibition assay and structural simulation of the complex. These results showed that the newly developed strategy has the advantage that the number of targets identified via ultrafiltration-HPLC can be narrowed from many false positives. However, not all false positives can be eliminated with this approach. Some potent inhibitors might also be excluded with the use of this method. The limitations of this method are also discussed herein. Copyright © 2017 Elsevier B.V. All rights reserved.

Understanding the Molecular Determinant of Reversible Human Monoamine Oxidase B Inhibitors Containing 2H-Chromen-2-One Core: Structure-Based and Ligand-Based Derived Three-Dimensional Quantitative Structure-Activity Relationships Predictive Models.

PubMed

Mladenović, Milan; Patsilinakos, Alexandros; Pirolli, Adele; Sabatino, Manuela; Ragno, Rino

2017-04-24

Monoamine oxidase B (MAO B) catalyzes the oxidative deamination of aryalkylamines neurotransmitters with concomitant reduction of oxygen to hydrogen peroxide. Consequently, the enzyme's malfunction can induce oxidative damage to mitochondrial DNA and mediates development of Parkinson's disease. Thus, MAO B emerges as a promising target for developing pharmaceuticals potentially useful to treat this vicious neurodegenerative condition. Aiming to contribute to the development of drugs with the reversible mechanism of MAO B inhibition only, herein, an extended in silico-in vitro procedure for the selection of novel MAO B inhibitors is demonstrated, including the following: (1) definition of optimized and validated structure-based three-dimensional (3-D) quantitative structure-activity relationships (QSAR) models derived from available cocrystallized inhibitor-MAO B complexes; (2) elaboration of SAR features for either irreversible or reversible MAO B inhibitors to characterize and improve coumarin-based inhibitor activity (Protein Data Bank ID: 2V61 ) as the most potent reversible lead compound; (3) definition of structure-based (SB) and ligand-based (LB) alignment rule assessments by which virtually any untested potential MAO B inhibitor might be evaluated; (4) predictive ability validation of the best 3-D QSAR model through SB/LB modeling of four coumarin-based external test sets (267 compounds); (5) design and SB/LB alignment of novel coumarin-based scaffolds experimentally validated through synthesis and biological evaluation in vitro. Due to the wide range of molecular diversity within the 3-D QSAR training set and derived features, the selected N probe-derived 3-D QSAR model proves to be a valuable tool for virtual screening (VS) of novel MAO B inhibitors and a platform for design, synthesis and evaluation of novel active structures. Accordingly, six highly active and selective MAO B inhibitors (picomolar to low nanomolar range of activity) were disclosed as a result of rational SB/LB 3D QSAR design; therefore, D123 (IC 50 = 0.83 nM, K i = 0.25 nM) and D124 (IC 50 = 0.97 nM, K i = 0.29 nM) are potential lead candidates as anti-Parkinson's drugs.

Ras inhibitors display an anti-metastatic effect by downregulation of lysyl oxidase through inhibition of the Ras-PI3K-Akt-HIF-1α pathway.

PubMed

Yoshikawa, Yoko; Takano, Osamu; Kato, Ichiro; Takahashi, Yoshihisa; Shima, Fumi; Kataoka, Tohru

2017-12-01

Metastasis stands as the major obstacle for the survival from cancers. Nonetheless most existing anti-cancer drugs inhibit only cell proliferation, and discovery of agents having both anti-proliferative and anti-metastatic properties would be more beneficial. We previously reported the discovery of small-molecule Ras inhibitors, represented by Kobe0065, that displayed anti-proliferative activity on xenografts of human colorectal cancer (CRC) cell line SW480 carrying the K-ras G12V gene. Here we show that treatment of cancer cells carrying the activated ras genes with Kobe0065 or a siRNA targeting Ras downregulates the expression of lysyl oxidase (LOX), which has been implicated in metastasis. LOX expression is enhanced by co-expression of Ras G12V through activation of phosphatidylinositol 3-kinase (PI3K)/Akt and concomitant accumulation of hypoxia-inducible factor (HIF)-1α. Furthermore, Kobe0065 effectively inhibits not only migration and invasion of cancer cells carrying the activated ras genes but also lung metastasis of human CRC cell line SW620 carrying the K-ras G12V gene. Collectively, these results indicate that Kobe0065 prevents metastasis through inhibition of the Ras-PI3K-Akt-HIF-1α-LOX signaling and suggest that Ras inhibitors in general might exhibit both anti-proliferative and anti-metastatic properties toward cancer cells carrying the activated ras genes. Copyright © 2017 Elsevier B.V. All rights reserved.

The xanthine oxidase inhibitor febuxostat suppresses development of nonalcoholic steatohepatitis in a rodent model.

PubMed

Nakatsu, Yusuke; Seno, Yasuyuki; Kushiyama, Akifumi; Sakoda, Hideyuki; Fujishiro, Midori; Katasako, Aya; Mori, Keiichi; Matsunaga, Yasuka; Fukushima, Toshiaki; Kanaoka, Ryuhei; Yamamotoya, Takeshi; Kamata, Hideaki; Asano, Tomoichiro

2015-07-01

Xanthine oxidase (XO) is an enzyme involved in the production of uric acid (UA) from purine nucleotides. Numerous recent studies have revealed the likelihood of metabolic syndrome including nonalcoholic fatty liver disease (NAFLD) or steatohepatitis (NASH) to be related to hyperuricemia. However, it remains unclear whether elevated serum UA during the development of NAFLD or NASH is a cause or a consequence of these diseases. In this study, the XO inhibitor febuxostat was administered to two types of NASH model mice. Febuxostat exerted a strong protective effect against NASH development induced by a high-fat diet containing trans fatty acid (HFDT). In contrast, methionine choline-deficient-diet-induced NASH development not accompanied by hyperuricemia showed no UA normalization, suggesting that the ameliorating effect of febuxostat occurs via the normalization of hyperuricemia itself and/or accompanying molecular mechanism(s) such as oxidative stress. In the HFDT-fed mice, hyperuricemia, elevated alanine aminotransferase, and increased Tunnel-positive cells in the liver were normalized by febuxostat administration. In addition, upregulation of fatty acid oxidation-related genes, fibrotic change, and increases in collagen deposition, inflammatory cytokine expressions, and lipid peroxidation in the HFDT-fed mice were also normalized by febuxostat administration. Taken together, these observations indicate that administration of febuxostat has a protective effect against HFDT-induced NASH development, suggesting the importance of XO in its pathogenesis. Thus XO inhibitors are potentially potent therapies for patients with NASH, particularly that associated with hyperuricemia. Copyright © 2015 the American Physiological Society.

Potent inhibition of monoamine oxidase A by decursin from Angelica gigas Nakai and by wogonin from Scutellaria baicalensis Georgi.

PubMed

Lee, Hyun Woo; Ryu, Hyung Won; Kang, Myung-Gyun; Park, Daeui; Lee, Hanna; Shin, Heung Mook; Oh, Sei-Ryang; Kim, Hoon

2017-04-01

During the ongoing search for new monoamine oxidase (MAO) inhibitors, five coumarin derivatives and eight flavonoids were isolated from the roots of Angelica gigas Nakai and Scutellaria baicalensis Georgi, respectively. Of the phytochemicals, decursin (4) was found to potently and selectively inhibit human MAO-A (IC 50 =1.89μM). The IC 50 value of 4 for MAO-A belonged to the lowest group in herbal sources and was similar to that of toloxatone (1.78μM), a marketed drug. Wogonin (11) effectively inhibited MAO-A and MAO-B (IC 50 =6.35 and 20.8μM, respectively). Furthermore, compounds 5 (decursinol angelate) and 10 (baicalein) were observed to selectively and moderately inhibit MAO-A. In addition, compound 4 reversibly and competitively inhibited MAO-A with a K i of 0.17μM. Compound 11 also competitively inhibited MAO-A and MAO-B (K i =0.56 and 1.96μM, respectively). Molecular docking simulation revealed that 4 interacts with Asn181 residue of MAO-A or Asn116 residue of MAO-B by formation of hydrogen bond. The findings suggest compounds 4 and 11 be considered as new potent and reversible MAO-A inhibitors or useful lead compounds for the developments of MAO inhibitors for the treatment of disorders like depression, Parkinson's disease and Alzheimer disease. Copyright © 2017 Elsevier B.V. All rights reserved.

Indole alkaloids of Psychotria as multifunctional cholinesterases and monoamine oxidases inhibitors.

PubMed

Passos, Carolina S; Simões-Pires, Claudia A; Nurisso, Alessandra; Soldi, Tatiane C; Kato, Lucilia; de Oliveira, Cecilia M A; de Faria, Emiret O; Marcourt, Laurence; Gottfried, Carmem; Carrupt, Pierre-Alain; Henriques, Amélia T

2013-02-01

Thirteen Psychotria alkaloids were evaluated regarding their interactions with acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and monoamine oxidases A and B (MAO-A and MAO-B), which are enzymatic targets related with neurodegenerative diseases. Two quaternary β-carboline alkaloids, prunifoleine and 14-oxoprunifoleine, inhibited AChE, BChE and MAO-A with IC(50) values corresponding to 10 and 3.39 μM for AChE, 100 and 11 μM for BChE, and 7.41 and 6.92 μM for MAO-A, respectively. Both compounds seem to behave as noncompetitive AChE inhibitors and time-dependent MAO-A inhibitors. In addition, the monoterpene indole alkaloids (MIAs) angustine, vallesiachotamine lactone, E-vallesiachotamine and Z-vallesiachotamine inhibited BChE and MAO-A with IC(50) values ranging from 3.47 to 14 μM for BChE inhibition and from 0.85 to 2.14 μM for MAO-A inhibition. Among the tested MIAs, angustine is able to inhibit MAO-A in a reversible and competitive way while the three vallesiachotamine-like alkaloids display a time-dependent inhibition on this target. Docking calculations were performed in order to understand the binding mode between the most active ligands and the selected targets. Taken together, our findings established molecular details of AChE, BChE and MAO-A inhibition by quaternary β-carboline alkaloids and MIAs from Psychotria, suggesting these secondary metabolites are scaffolds for the development of multifunctional compounds against neurodegeneration. Copyright © 2012 Elsevier Ltd. All rights reserved.

Diapocynin, a dimer of the NADPH oxidase inhibitor apocynin, reduces ROS production and prevents force loss in eccentrically contracting dystrophic muscle.

PubMed

Ismail, Hesham M; Scapozza, Leonardo; Ruegg, Urs T; Dorchies, Olivier M

2014-01-01

Elevation of intracellular Ca2+, excessive ROS production and increased phospholipase A2 activity contribute to the pathology in dystrophin-deficient muscle. Moreover, Ca2+, ROS and phospholipase A2, in particular iPLA2, are thought to potentiate each other in positive feedback loops. NADPH oxidases (NOX) have been considered as a major source of ROS in muscle and have been reported to be overexpressed in muscles of mdx mice. We report here on our investigations regarding the effect of diapocynin, a dimer of the commonly used NOX inhibitor apocynin, on the activity of iPLA2, Ca2+ handling and ROS generation in dystrophic myotubes. We also examined the effects of diapocynin on force production and recovery ability of isolated EDL muscles exposed to eccentric contractions in vitro, a damaging procedure to which dystrophic muscle is extremely sensitive. In dystrophic myotubes, diapocynin inhibited ROS production, abolished iPLA2 activity and reduced Ca2+ influx through stretch-activated and store-operated channels, two major pathways responsible for excessive Ca2+ entry in dystrophic muscle. Diapocynin also prevented force loss induced by eccentric contractions of mdx muscle close to the value of wild-type muscle and reduced membrane damage as seen by Procion orange dye uptake. These findings support the central role played by NOX-ROS in the pathogenic cascade leading to muscular dystrophy and suggest diapocynin as an effective NOX inhibitor that might be helpful for future therapeutic approaches.

The Use of Multiscale Molecular Simulations in Understanding a Relationship between the Structure and Function of Biological Systems of the Brain: The Application to Monoamine Oxidase Enzymes

PubMed Central

Vianello, Robert; Domene, Carmen; Mavri, Janez

2016-01-01

HIGHLIGHTS Computational techniques provide accurate descriptions of the structure and dynamics of biological systems, contributing to their understanding at an atomic level.Classical MD simulations are a precious computational tool for the processes where no chemical reactions take place.QM calculations provide valuable information about the enzyme activity, being able to distinguish among several mechanistic pathways, provided a carefully selected cluster model of the enzyme is considered.Multiscale QM/MM simulation is the method of choice for the computational treatment of enzyme reactions offering quantitative agreement with experimentally determined reaction parameters.Molecular simulation provide insight into the mechanism of both the catalytic activity and inhibition of monoamine oxidases, thus aiding in the rational design of their inhibitors that are all employed and antidepressants and antiparkinsonian drugs. Aging society and therewith associated neurodegenerative and neuropsychiatric diseases, including depression, Alzheimer's disease, obsessive disorders, and Parkinson's disease, urgently require novel drug candidates. Targets include monoamine oxidases A and B (MAOs), acetylcholinesterase (AChE), butyrylcholinesterase (BChE), and various receptors and transporters. For rational drug design it is particularly important to combine experimental synthetic, kinetic, toxicological, and pharmacological information with structural and computational work. This paper describes the application of various modern computational biochemistry methods in order to improve the understanding of a relationship between the structure and function of large biological systems including ion channels, transporters, receptors, and metabolic enzymes. The methods covered stem from classical molecular dynamics simulations to understand the physical basis and the time evolution of the structures, to combined QM, and QM/MM approaches to probe the chemical mechanisms of enzymatic activities and their inhibition. As an illustrative example, the later will focus on the monoamine oxidase family of enzymes, which catalyze the degradation of amine neurotransmitters in various parts of the brain, the imbalance of which is associated with the development and progression of a range of neurodegenerative disorders. Inhibitors that act mainly on MAO A are used in the treatment of depression, due to their ability to raise serotonin concentrations, while MAO B inhibitors decrease dopamine degradation and improve motor control in patients with Parkinson disease. Our results give strong support that both MAO isoforms, A and B, operate through the hydride transfer mechanism. Relevance of MAO catalyzed reactions and MAO inhibition in the context of neurodegeneration will be discussed. PMID:27471444

Co-occurring Conditions Toolkit: Mild Traumatic Brain Injury and Psychological Health

DTIC Science & Technology

2009-01-01

in OD yy Contraindi- cated with MAOIs within past 14 days of therapy yy Bupropion, Haloperidol and SSRIs may increase the TCA’s level which... Haloperidol (Haldol) yy Initial PTSD dose = 0.5mg TID or 1mg BID yy Max PTSD = 5mg QID yy Used in PTSD but therapeu- tic doses not established...yy The Opioid side effect of delirium may be treated with Haloperi- dol if phar- macologic treatment is deemed necessary yy Haloperidol may

Effects of a diphenyl-ether herbicide, oxyfluorfen, on human BFU-E/CFU-E development and haemoglobin synthesis.

PubMed

Rio, B; Parent-Massin, D; Lautraite, S; Hoellinger, H

1997-02-01

The diphenyl-ether herbicides exert their phytotoxic activity by preventing chlorophyll formation in plants as a result of inhibition of protoporphyrinogen oxidase. This enzyme is the last step of the common pathway for chlorophyll and haem biosynthesis. The aim of this work is to determine whether herbicide inhibitors of plant protoporphyrinogen oxidase could act on the human protoporphyrinogen oxidase involved in haemoglobin synthesis and cause heamatologic diseases. Human erythroblastic progenitors (BFU-E/CFU-E: Burst Forming Unit-Erythroid and Colony Forming Unit-Erythroid) were exposed to oxyfluorfen, a diphenyl-ether herbicide in the presence of erythropoietin, and the haematoxicity evaluated in vitro by scoring the development of BFU-E/CFU-E colonies after 7 and 14 days of culture. The toxic effect on differentiation has been evaluated using four criteria: morphology, total protein, total porphyrin, and haemoglobin content. The study of BFU-E/CFU-E proliferation and differentiation showed a cytotoxic effect of oxyfluorfen only at very high concentrations. In contrast, haemoglobin synthesis can be inhibited by concentration of oxyfluorfen (10(-4) M) that have no adverse effect on cellular proliferation.

[The serotonin syndrome. Fatal course of intoxication with citalopram and moclobemide].

PubMed

Cassens, S; Nickel, E A; Quintel, M; Neumann, P

2006-11-01

The serotonin syndrome is caused by a drug-induced increase of the intrasynaptic serotonin concentration. Milder forms of the syndrome may be difficult to diagnose because of the variability of symptoms. Severe forms often rapidly turn into a life-threatening situation, therefore the serotonin syndrome may be a challenge for physicians. We describe the pathophysiology and therapeutic options of the serotonin syndrome and report about a 42-year-old female patient who ingested large amounts of moclobemide, a monoamine oxidase inhibitor, and citalopram, a selective serotonin reuptake inhibitor, for attempted suicide. Within a few hours the patient developed a lethal serotonin syndrome although ICU therapy was initiated immediately.

Dissecting blue light signal transduction pathway in leaf epidermis using a pharmacological approach.

PubMed

Živanović, Branka D; Shabala, Lana I; Elzenga, Theo J M; Shabala, Sergey N

2015-10-01

Blue light signalling pathway in broad bean leaf epidermal cells includes key membrane transporters: plasma- and endomembrane channels and pumps of H (+) , Ca (2+) and K (+) ions, and plasma membrane redox system. Blue light signalling pathway in epidermal tissue isolated from the abaxial side of fully developed Vicia faba leaves was dissected by measuring the effect of inhibitors of second messengers on net K(+), Ca(2+) and H(+) fluxes using non-invasive ion-selective microelectrodes (the MIFE system). Switching the blue light on-off caused transient changes of the ion fluxes. The effects of seven groups of inhibitors were tested in this study: CaM antagonists, ATPase inhibitors, Ca(2+) anatagonists or chelators, agents affecting IP3 formation, redox system inhibitors, inhibitors of endomembrane Ca(2+) transport systems and an inhibitor of plasma membrane Ca(2+)-permeable channels. Most of the inhibitors had a significant effect on steady-state (basal) net fluxes, as well as on the magnitude of the transient ion flux responses to blue light fluctuations. The data presented in this study suggest that redox signalling and, specifically, plasma membrane NADPH oxidase and coupled Ca(2+) and K(+) fluxes play an essential role in blue light signal transduction.

Analysis of monoamine oxidase (MAO) enzymatic activity by high-performance liquid chromatography-diode array detection combined with an assay of oxidation with a peroxidase and its application to MAO inhibitors from foods and plants.

PubMed

Herraiz, Tomás; Flores, Andrea; Fernández, Lidia

2018-01-15

Monoamine oxidase (MAO) enzymes catalyze the oxidative deamination of biogenic amines and neurotransmitters and produce ammonia, aldehydes, and hydrogen peroxide which is involved in oxidative processes. Inhibitors of MAO-A and -B isozymes are useful as antidepressants and neuroprotectants. The assays of MAO usually measure amine oxidation products or hydrogen peroxide by spectrophotometric techniques. Those assays are often compromised by interfering compounds resulting in poor results. This research describes a new method that combines in the same assay the oxidative deamination of kynuramine to 4-hydroxyquinoline analyzed by HPLC-DAD with the oxidation of tetramethylbenzidine (TMB) (or Amplex Rex) by horseradish peroxidase (HRP) in presence of hydrogen peroxide. The new method was applied to study the inhibition of human MAO-A and -B by bioactive compounds including β-carboline alkaloids and flavonoids occurring in foods and plants. As determined by HPLC-DAD, β-carbolines, methylene blue, kaempferol and clorgyline inhibited MAO-A and methylene blue, 5-nitroindazole, norharman and deprenyl inhibited MAO-B, and all of them inhibited the oxidation of TMB in the same extent. The flavonoids catechin and cyanidin were not inhibitors of MAO by HPLC-DAD but highly inhibited the oxidation of TMB (or Amplex Red) by peroxidase whereas quercetin and resveratrol were moderate inhibitors of MAO-A by HPLC-DAD, but inhibited the peroxidase assay in a higher level. For some phenolic compounds, using the peroxidase-coupled assay to measure MAO activity led to mistaken results. The new method permits to discern between true inhibitors of MAO from those that are antioxidants and which interfere with peroxidase assays but do not inhibit MAO. For true inhibitors of MAO, inhibition as determined by HPLC-DAD correlated well with inhibition of the oxidation of TMB and this approach can be used to assess the in vitro antioxidant activity (less hydrogen peroxide production) resulting from MAO inhibition. Copyright © 2017 Elsevier B.V. All rights reserved.

Polyphenol oxidase activity from three sicilian artichoke [ Cynara cardunculus L. Var. scolymus L. (Fiori)] cultivars: studies and technological application on minimally processed production.

PubMed

Todaro, Aldo; Peluso, Orazio; Catalano, Anna Eghle; Mauromicale, Giovanni; Spagna, Giovanni

2010-02-10

Several papers helped with the development of more methods to control browning, or study thermal polyphenol oxidase (PPO) inactivation, but did not provide any solutions to technological process problems and food process improvement. Artichokes [ Cynara cardunculus L. var. scolymus L. (Fiori)] are susceptible to browning; this alteration could affect and reduce the suitability for its use, fresh or processed. Within this study, the catecholase and cresolase activities of PPO from three different Sicilian artichokes cultivar were characterized with regard to substrate specificity and enzyme kinetics, optimum pH and temperature, temperature and pH stability, and inhibitor test; all of the results were used for technological purposes, particularly to optimize minimally processed productions (ready-to-eat and cook-chilled artichokes).

Genetic Phagocyte NADPH Oxidase Deficiency Enhances Nonviable Candida albicans-Induced Inflammation in Mouse Lungs.

PubMed

Endo, Daiki; Fujimoto, Kenta; Hirose, Rika; Yamanaka, Hiroko; Homme, Mizuki; Ishibashi, Ken-Ichi; Miura, Noriko; Ohno, Naohito; Aratani, Yasuaki

2017-02-01

Patients with chronic granulomatous disease (CGD) have mutated phagocyte NADPH oxidase, resulting in reduced production of reactive oxygen species (ROS). While the mechanism underlying hyperinfection in CGD is well understood, the basis for inflammatory disorders that arise in the absence of evident infection has not been fully explained. This study aimed to evaluate the effect of phagocyte NADPH oxidase deficiency on lung inflammation induced by nonviable Candida albicans (nCA). Mice deficient in this enzyme (CGD mice) showed more severe neutrophilic pneumonia than nCA-treated wild-type mice, which exhibited significantly higher lung concentrations of interleukin (IL)-1β, tumor necrosis factor (TNF)-α, and keratinocyte-derived chemokine (KC). Neutralization of these proinflammatory mediators significantly reduced neutrophil infiltration. In vitro, production of IL-1β and TNF-α from neutrophils and that of KC from macrophages was enhanced in nCA-stimulated neutrophils from CGD mice. Expression of IL-1β mRNA was higher in the stimulated CGD neutrophils than in the stimulated wild-type cells, concomitant with upregulation of nuclear factor (NF)-κB and its upstream regulator extracellular-signal regulated kinase (ERK) 1/2. Pretreatment with an NADPH oxidase inhibitor significantly enhanced IL-1β production in the wild-type neutrophils stimulated with nCA. These results suggest that lack of ROS production because of NADPH oxidase deficiency results in the production of higher levels of proinflammatory mediators from neutrophils and macrophages, which may at least partly contribute to the exacerbation of nCA-induced lung inflammation in CGD mice.

Contraindications to vasoconstrictors in dentistry: Part III. Pharmacologic interactions.

PubMed

Goulet, J P; Pérusse, R; Turcotte, J Y

1992-11-01

This article discusses the relative contraindications to the use of vasoconstrictor in patients currently medicated with tricyclic antidepressants, monoamine oxidase inhibitors, phenothiazines and beta-blockers. It reviews drug interactions and emphasizes potential detrimental systemic effects that epinephrine contained in local anesthetics can have when administered concomitantly with these drugs. Finally, special considerations are expressed concerning patients who abuse illicit drugs such as cocaine.

Rhaponticum acaule (L) DC essential oil: chemical composition, in vitro antioxidant and enzyme inhibition properties.

PubMed

Mosbah, Habib; Chahdoura, Hassiba; Kammoun, Jannet; Hlila, Malek Besbes; Louati, Hanen; Hammami, Saoussen; Flamini, Guido; Achour, Lotfi; Selmi, Boulbaba

2018-03-05

α-glucosidase is a therapeutic target for diabetes mellitus (DM) and α-glucosidase inhibitors play a vital role in the treatments for the disease. Furthermore, xanthine oxidase (XO) is a key enzyme that catalyzes hypoxanthine and xanthine to uric acid which at high levels can lead to hyperuricemia which is an important cause of gout. Pancreatic lipase (PL) secreted into the duodenum plays a key role in the digestion and absorption of fats. For its importance in lipid digestion, PL represents an attractive target for obesity prevention. The flowers essential oil of Rhaponticum acaule (L) DC (R. acaule) was characterized using gas chromatography-mass spectrometry (GC-MS). The antioxidant activities of R. acaule essential oil (RaEO) were also determined using 2,2'-azinobis-3-ethylbenzothiazoline-6-sulfonic acid (ABTS), reducing power, phosphomolybdenum, and DNA nicking assays. The inhibitory power of RaEO against α-glucosidase, xanthine oxidase and pancreatic lipase was evaluated. Enzyme kinetic studies using Michaelis-Menten and the derived Lineweaver-Burk (LB) plots were performed to understand the possible mechanism of inhibition exercised by the components of this essential oil. The result revealed the presence of 26 compounds (97.4%). The main constituents include germacrene D (49.2%), methyl eugenol (8.3%), (E)-β-ionone (6.2%), β-caryophyllene (5.7%), (E,E)-α-farnesene (4.2%), bicyclogermacrene (4.1%) and (Z)-α-bisabolene (3.7%). The kinetic inhibition study showed that the essential oil demonstrated a strong α-glucosidase inhibiton and it was a mixed inhibitor. On the other hand, our results evidenced that this oil exhibited important xanthine oxidase inhibitory effect, behaving as a non-competitive inhibitor. The essential oil inhibited the turkey pancreatic lipase, with maximum inhibition of 80% achieved at 2 mg/mL. Furthermore, the inhibition of turkey pancreatic lipase by RaEO was an irreversible one. The results revealed that the RaEO is a new promising potential source of antioxidant compounds, endowed with good practical applications for human health.

Benzoate, a D-amino acid oxidase inhibitor, for the treatment of early-phase Alzheimer disease: a randomized, double-blind, placebo-controlled trial.

PubMed

Lin, Chieh-Hsin; Chen, Ping-Kun; Chang, Yue-Cune; Chuo, Liang-Jen; Chen, Yan-Syun; Tsai, Guochuan E; Lane, Hsien-Yuan

2014-05-01

N-methyl-D-aspartate receptor (NMDAR)-mediated neurotransmission is vital for learning and memory. Hypofunction of NMDAR has been reported to play a role in the pathophysiology of Alzheimer disease (AD), particularly in the early phase. Enhancing NMDAR activation might be a novel treatment approach. One of the methods to enhance NMDAR activity is to raise the levels of NMDA coagonists by blocking their metabolism. This study examined the efficacy and safety of sodium benzoate, a D-amino acid oxidase inhibitor, for the treatment of amnestic mild cognitive impairment and mild AD. We conducted a randomized, double-blind, placebo-controlled trial in four major medical centers in Taiwan. Sixty patients with amnestic mild cognitive impairment or mild AD were treated with 250-750 mg/day of sodium benzoate or placebo for 24 weeks. Alzheimer's Disease Assessment Scale-cognitive subscale (the primary outcome) and global function (assessed by Clinician Interview Based Impression of Change plus Caregiver Input) were measured every 8 weeks. Additional cognition composite was measured at baseline and endpoint. Sodium benzoate produced a better improvement than placebo in Alzheimer's Disease Assessment Scale-cognitive subscale (p = .0021, .0116, and .0031 at week 16, week 24, and endpoint, respectively), additional cognition composite (p = .007 at endpoint) and Clinician Interview Based Impression of Change plus Caregiver Input (p = .015, .016, and .012 at week 16, week 24, and endpoint, respectively). Sodium benzoate was well-tolerated without evident side-effects. Sodium benzoate substantially improved cognitive and overall functions in patients with early-phase AD. The preliminary results show promise for D-amino acid oxidase inhibition as a novel approach for early dementing processes. Copyright © 2014 Society of Biological Psychiatry. Published by Elsevier Inc. All rights reserved.

Challenge Integrity: The Cell-Penetrating Peptide BP100 Interferes with the Auxin-Actin Oscillator.

PubMed

Eggenberger, Kai; Sanyal, Papia; Hundt, Svenja; Wadhwani, Parvesh; Ulrich, Anne S; Nick, Peter

2017-01-01

Actin filaments are essential for the integrity of the cell membrane. In addition to this structural role, actin can modulate signaling by altering polar auxin flow. On the other hand, the organization of actin filaments is modulated by auxin constituting a self-referring signaling hub. Although the function of this auxin–actin oscillator is not clear, there is evidence for a functional link with stress signaling activated by the NADPH oxidase Respiratory burst oxidase Homolog (RboH). In the current work, we used the cell-penetrating peptide BP100 to induce a mild and transient perturbation of membrane integrity. We followed the response of actin to the BP100 uptake in a green fluorescent protein (GFP)-tagged actin marker line of tobacco Bright Yellow 2 (BY-2) cells by spinning disc confocal microscopy. We observed that BP100 enters in a stepwise manner and reduces the extent of actin remodeling. This actin ‘freezing’ can be rescued by the natural auxin IAA, and mimicked by the auxin-efflux inhibitor 1-napthylphthalamic acid (NPA). We further tested the role of the membrane-localized NADPH oxidase RboH using the specific inhibitor diphenyl iodonium (DPI), and found that DPI acts antagonistically to BP100, although DPI alone can induce a similar actin ‘freezing’ as well. We propose a working model, where the mild violation of membrane integrity by BP100 stimulates RboH, and the resulting elevated levels of reactive oxygen species interfere with actin dynamicity. The mitigating effect of auxin is explained by competition of auxin- and RboH-triggered signaling for superoxide anions. This self-referring auxin–actin–RboH hub might be essential for integrity sensing.

Peroxide generation by p47phox-Src activation of Nox2 has a key role in protein kinase C-induced arterial smooth muscle contraction.

PubMed

Gupte, Sachin A; Kaminski, Pawel M; George, Shimran; Kouznestova, Lioubov; Olson, Susan C; Mathew, Rajamma; Hintze, Thomas H; Wolin, Michael S

2009-04-01

Protein kinase C (PKC) stimulation of NAD(P)H oxidases (Nox) is an important component of multiple vascular disease processes; however, the relationship between oxidase activation and the regulation of vascular smooth muscle contraction by PKC remains poorly understood. Therefore, we examined the signaling cascade of PKC-elicited Nox activation and the role of superoxide and hydrogen peroxide in mediating PKC-induced vascular contraction. Endothelium-denuded bovine coronary arteries showed a PKC-dependent basal production of lucigenin (5 muM)-detected Nox oxidase-derived superoxide, which was stimulated fourfold by PKC activation with 10 muM phorbol 12,13-dibutyrate (PDBu). PDBu appeared to increase superoxide generation by Nox2 through both p47(phox) and peroxide-dependent Src activation mechanisms based on the actions of inhibitors, properties of Src phosphorylation, and the loss of responses in aorta from mice deficient in Nox2 and p47(phox). The actions of inhibitors of contractile regulating mechanisms, scavengers of superoxide and peroxide, and responses in knockout mouse aortas suggest that a major component of the contraction elicited by PDBu appeared to be mediated through peroxide derived from Nox2 activation stimulating force generation through Rho kinase and calmodulin kinase-II mechanisms. Superoxide generated by PDBu also attenuated relaxation to nitroglycerin. Peroxide-derived from Nox2 activation by PKC appeared to be a major contributor to the thromboxane A(2) receptor agonist U46619 (100 nM)-elicited contraction of coronary arteries. Thus a p47(phox) and Src kinase activation of peroxide production by Nox2 appears to be an important contributor to vascular contractile mechanisms mediated through activation of PKC.

A rapid and sensitive assay method for measuring amine oxidase based on hydrogen peroxide-titanium complex formation.

PubMed

Nag; Saha; Choudhuri

2000-08-22

Hydrogenperoxide (H(2)O(2)) is an end product of diamine and polyamine oxidation by their respective oxidase enzymes. A new sensitive assay method is based on a H(2)O(2)-titanium (Ti) complex formation as an indicator of H(2)O(2) production due to polyamine oxidation. The orange-yellow coloured H(2)O(2)-Ti complex was measured at 410 nm in a Shimadzu spectrophotometer. The assay conditions for maximum diamine oxidase (DAO) and polyamine oxidase (PAO) as standardized here using the hypocotyl tissues of Vigna catjang Endl. cv Pusa Barsati consisted of pH 7.4 (40 mM potassium phosphate buffer), 3 mM substrate (putrescine or spermine), 37 degrees C incubation temperature and 30 min incubation time in the presence of catechol (10(-2) M) used as an inhibitor of both peroxidase and catalase activity. The method described here was significantly more sensitive than the starch-iodide method [T.A. Smith, Biochem. Biophys. Res. Commun. 41 (1970) 1452-1456], which could be improved further if measured under the same assay conditions as described for the H(2)O(2)-Ti method. Sensitivity of the present method was tested by assaying DAO/PAO activity in auxin treated hypocotyls of Vigna and comparing it with the starch-iodide method in two other plant samples.

Characterization of oxidative phosphorylation in the colorless chlorophyte Polytomella sp. Its mitochondrial respiratory chain lacks a plant-like alternative oxidase.

PubMed

Reyes-Prieto, Adrián; El-Hafidi, Mohammed; Moreno-Sánchez, Rafael; González-Halphen, Diego

2002-07-01

The presence of an alternative oxidase (AOX) in Polytomella sp., a colorless relative of Chlamydomonas reinhardtii, was explored. Oxygen uptake in Polytomella sp. mitochondria was inhibited by KCN (94%) or antimycin (96%), and the remaining cyanide-resistant respiration was not blocked by the AOX inhibitors salicylhydroxamic acid (SHAM) or n-propylgallate. No stimulation of an AOX activity was found upon addition of either pyruvate, alpha-ketoglutarate, or AMP, or by treatment with DTT. An antibody raised against C. reinhardtii AOX did not recognized any polypeptide band of Polytomella sp. mitochondria in Western blots. Also, PCR experiments and Southern blot analysis failed to identify an Aox gene in this colorless alga. Finally, KCN exposure of cell cultures failed to stimulate an AOX activity. Nevertheless, KCN exposure of Polytomella sp. cells induced diminished mitochondrial respiration (20%) and apparent changes in cytochrome c oxidase affinity towards cyanide. KCN-adapted cells exhibited a significant increase of a-type cytochromes, suggesting accumulation of inactive forms of cytochrome c oxidase. Another effect of KCN exposure was the reduction of the protein/fatty acid ratio of mitochondrial membranes, which may affect the observed respiratory activity. We conclude that Polytomella lacks a plant-like AOX, and that its corresponding gene was probably lost during the divergence of this colorless genus from its close photosynthetic relatives.

Correlation of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine Neurotoxicity with Blood-Brain Barrier Monoamine Oxidase Activity

NASA Astrophysics Data System (ADS)

Kalaria, Rajesh N.; Mitchell, Mary Jo; Harik, Sami I.

1987-05-01

Systemic administration of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine (MPTP) causes parkinsonism in humans and subhuman primates, but not in rats and many other laboratory animals; mice are intermediate in their susceptibility. Since MPTP causes selective dopaminergic neurotoxicity when infused directly into rat substantia nigra, we hypothesized that systemic MPTP may be metabolized by monoamine oxidase and/or other enzymes in rat brain capillaries and possibly other peripheral organs and thus prevented from reaching its neuronal sites of toxicity. We tested this hypothesis by assessing monoamine oxidase in isolated cerebral microvessels of humans, rats, and mice by measuring the specific binding of [3H]pargyline, an irreversible monoamine oxidase inhibitor, and by estimating the rates of MPTP and benzylamine oxidation. [3H]Pargyline binding to rat cerebral microvessels was about 10-fold higher than to human or mouse microvessels. Also, MPTP oxidation by rat brain microvessels was about 30-fold greater than by human microvessels; mouse microvessels yielded intermediate values. These results may explain, at least in part, the marked species differences in susceptibility to systemic MPTP. They also suggest the potential importance of ``enzyme barriers'' at the blood-brain interface that can metabolize toxins not excluded by structural barriers, and may provide biological bases for developing therapeutic strategies for the prevention of MPTP-induced neurotoxicity and other neurotoxic conditions including, possibly, Parkinson disease.

Seahorse Xfe24 Extracellular Flux Analyzer-based analysis of cellular respiration in Caenorhabditis elegans

PubMed Central

Luz, Anthony L.; Smith, Latasha L.; Rooney, John P.

2015-01-01

Mitochondria are critical for their role in ATP production as well as multiple nonenergetic functions, and mitochondrial dysfunction is causal in myriad human diseases. Less well appreciated is the fact that mitochondria integrate environmental and inter- as well as intracellular signals to modulate function. Because mitochondria function in an organismal milieu, there is need for assays capable of rapidly assessing mitochondrial health in vivo. Here, using the Seahorse XFe24 Extracellular Flux Analyzer and the pharmacological inhibitors dicyclohexylcarbodiimide (DCCD, ATP synthase inhibitor), carbonyl cyanide-p-trifluoromethoxyphenylhydrazone (FCCP, mitochondrial uncoupler) and sodium azide (cytochrome c oxidase inhibitor), we describe how to obtain in vivo measurements of the fundamental parameters (basal oxygen consumption rate (OCR), ATP-linked respiration, maximal OCR, spare respiratory capacity and proton leak) of the mitochondrial respiratory chain in the model organism Caenorhabditis elegans. PMID:26523474

Rasagiline (TVP-1012): a new selective monoamine oxidase inhibitor for Parkinson's disease.

PubMed

Guay, David R P

2006-12-01

This article reviews the chemistry, pharmacodynamics, pharmacokinetics, clinical efficacy, tolerability, drug-interaction potential, indications, dosing, and potential role of rasagiline mesylate, a new selective monoamine oxidase (MAO) type B (MAO-B) inhibitor, in the treatment of Parkinson's disease. A MEDLINE/PUBMED search (1986 through September 2006) was conducted to identify studies involving rasagiline written in English. Additional references were obtained from the bibliographies of these studies. All studies evaluating any aspect of rasagiline, including in vitro, in vivo (animal), and human studies, were reviewed. Rasagiline mesylate was developed with the goal of producing a selective MAO-B inhibitor that is not metabolized to (presumed) toxic metabolites (eg, amphetamine and methamphetamine, which are byproducts of the metabolism of selegiline, another selective MAO-B inhibitor). In vitro and in vivo data have confirmed the drug's selectivity for MAO-B. Rasagiline is almost completely eliminated by oxidative metabolism (catalyzed by cytochrome P-450 [CYP] isozyme 1A2) followed by renal excretion of conjugated parent compound and metabolites. Drug clearance is sufficiently slow to allow once-daily dosing. Several studies have documented its efficacy as monotherapy for early-stage disease and as adjunctive therapy in L-dopa recipients with motor fluctuations. As monotherapy, rasagiline is well tolerated with an adverse-effect profile similar to that of placebo. As adjunctive therapy, it exhibits the expected adverse effects of dopamine excess, which can be ameliorated by reducing the L-dopa dosage. CYP1A2 inhibitors slow the elimination of rasagiline and mandate dosage reduction. Hepatic impairment has an analogous effect. The recommended dosage regimens for monotherapy and adjunctive therapy are 1 and 0.5 mg PO QD, respectively. Despite the well-documented selectivity of rasagiline, the manufacturer recommends virtually all of the dietary (vis-à-vis tyramine) and drug restrictions of the nonselective MAO inhibitors. Although useful, selective MAO-B inhibitors have a limited role in Parkinson's disease. Of greater interest is the potential neuroprotective effect of rasagiline and its major metabolite, 1(R)-aminoindan, which may have great utility in a wide variety of neurodegenerative disorders of aging. In addition, bifunctional molecules combining selective MAO-B inhibition (based on the active moiety of rasagiline) with acetylcholinesterase inhibition or iron chelation may eventually be useful in Alzheimer's disease.

Evaluation of the Inhibitory Effects of Bavachinin and Bavachin on Human Monoamine Oxidases A and B

PubMed Central

Zarmouh, Najla O.; Mazzio, Elizabeth A.; Elshami, Faisel M.; Messeha, Samia S.; Eyunni, Suresh V. K.; Soliman, Karam F. A.

2015-01-01

Monoamine oxidase B inhibitors (MAO-BIs) are used in the early management of Parkinson's disease (PD). Long-term suspected side effects of MAO-B classical inhibitors established the need for safer alternative therapeutic agents. In our study, the flavanone bavachinin (BNN) and its analog bavachin (BVN) found in the seeds of Psoralea corylifolia L. ethanolic extract (PCSEE) were investigated for their human MAO-A and MAO-B (hMAO-A and hMAO-B) inhibition. Both PCSEE and BNN effectively reduced hMAO-B activity more than hMAO-A while BVN had activating effects. BNN showed selective hMAO-B inhibition (IC50 ~ 8.82 μM) more than hMAO-A (IC502009;~ 189.28 μM). BNN in the crude extract was determined by HPLC, also validated by TLC showing a yield of 0.21% PCSEE dry weight. BNN competitively inhibited hMAO-A and hMAO-B, with a lower hMAO-B K i than hMAO-A K i by 10.33-fold, and reduced hMAO-B K m/V max efficiency ratio to be comparable to the standard selegiline. Molecular docking examination of BNN and BVN predicted an indirect role of BNN C7-methoxy group for its higher affinity, selectivity, and reversibility as an MAO-BI. These findings suggest that BNN, which is known to be a potent PPAR-γ agonist, is a selective and competitive hMAO-B inhibitor and could be used in the management of PD. PMID:26557867

High throughput screening to identify natural human monoamine oxidase B inhibitors.

PubMed

Mazzio, E; Deiab, S; Park, K; Soliman, K F A

2013-06-01

Age-related increase in monoamine oxidase B (MAO-B) may contribute to CNS neurodegenerative diseases. Moreover, MAO-B inhibitors are used in the treatment of idiopathic Parkinson disease as preliminary monotherapy or adjunct therapy with L-dopa. To date, meager natural sources of MAO-B inhibitors have been identified, and the relative strength, potency and rank of many plants relative to standard drugs such as Selegiline (L-deprenyl,Eldepryl) are not known. In this work, we developed and utilized a high throughput enzyme microarray format to screen and evaluate 905 natural product extracts (0.025-.7 mg/ml) to inhibit human MAO-B derived from BTI-TN-5B1-4 cells infected with recombinant baculovirus. The protein sequence of purified enzyme was confirmed using 1D gel electrophoresis-matrix assisted laser desorption ionization -time-of-flight-tandem mass spectroscopy, and enzyme activity was confirmed by [1] substrate conversion (3-mM benzylamine) to H202 and [2] benzaldehyde. Of the 905 natural extracts tested, the lowest IC50s [<0.07 mg/ml] were obtained with extracts of Amur Corktree (Phellodendron amurense), Bakuchi Seed(Cyamopsis psoralioides), Licorice Root (Glycyrrhiza glabra/uralensis), Babchi (Psoralea corylifolia seed). The data also show, albeit to a lesser extent, inhibitory properties of herbs originating from the mint family (Lamiaceae) and Turmeric, Comfrey, Bringraj, Skullcap, Kava-kava, Wild Indigo, Gentian and Green Tea. In conclusion, the data reflect relative potency information by rank of commonly used herbs and plants that contain human MAO-B inhibitory properties in their natural form. Copyright © 2012 John Wiley & Sons, Ltd.

Sequential activation of JAKs, STATs and xanthine dehydrogenase/oxidase by hypoxia in lung microvascular endothelial cells.

PubMed

Wang, Guansong; Qian, Pin; Jackson, Fannie R; Qian, Guisheng; Wu, Guangyu

2008-01-01

Xanthine dehydrogenase/oxidase (XDH/XO) is associated with various pathological conditions related to the endothelial injury. However, the molecular mechanism underlying the activation of XDH/XO by hypoxia remains largely unknown. In this report, we determined whether the Janus kinases (JAKs) and signal transducers and activators of transcription (STATs) signaling pathway is involved in hypoxia-induced activation of XDH/XO in primary cultures of lung microvascular endothelial cells (LMVEC). We found that hypoxia significantly increased interleukin 6 (IL6) production in a time-dependent manner in LMVEC. Hypoxia also markedly augmented phosphorylation/activation of JAKs (JAK1, JAK2 and JAK3) and the JAK downstream effectors STATs (STAT3 and STAT5). Hypoxia-induced activation of STAT3 was blocked by IL6 antibodies, the JAK inhibitor AG490 and the suppressor of cytokine signaling 3 (SOCS3), implying that hypoxia-promoted IL6 secretion activates the JAK/STAT pathway in LMVEC. Phosphorylation and DNA-binding activity of STAT3 were also inhibited by the p38 MAPK inhibitor SB203580 and the phosphatidylinositol 3-kinase inhibitor LY294002, suggesting that multiple signaling pathways involved in STAT activation by hypoxia. Importantly, hypoxia promoted XDH/XO activation in LMVEC, which was markedly reversed by inhibiting the JAK-STAT pathway using IL6 antibodies, AG490 and SOCS3. These data demonstrated that JAKs, STATs and XDH/XO were sequentially activated by hypoxia. These data provide the first evidence indicating that the JAK-STAT pathway is involved in hypoxia-mediated XDH/XO activation in LMVEC.

Monamine oxidase inhibitors: current and emerging agents for Parkinson disease.

PubMed

Fernandez, Hubert H; Chen, Jack J

2007-01-01

Monoamine oxidase type B (MAO-B) is the predominant isoform responsible for the metabolic breakdown of dopamine in the brain. Selective inhibition of brain MAO-B results in elevation of synaptosomal dopamine concentrations. Data have been reported regarding the selective MAO-B inhibitors, rasagiline and selegiline, for the symptomatic treatment of Parkinson disease (PD). Selegiline has demonstrated efficacy as monotherapy in patients with early PD (Deprenyl and Tocopherol Antioxidative Therapy of Parkinsonism study), but evidence of selegiline efficacy as adjunctive treatment in levodopa-treated PD patients with motor fluctuations is equivocal. A new formulation of selegiline (Zydis selegiline) has been evaluated in 2 small, placebo-controlled studies as adjunctive therapy to levodopa. The Zydis formulation allows pregastric absorption of selegiline, minimizing first-pass metabolism, and thereby increasing selegiline bioavailability and reducing the concentration of amphetamine metabolites. Rasagiline is a selective, second-generation, irreversible MAO-B inhibitor, with at least 5 times the potency of selegiline in vitro and in animal models. Rasagiline has demonstrated efficacy in 1 large, randomized, double-blind, placebo-controlled trial (TVP-1012 in Early Monotherapy for Parkinson's Disease Outpatients) as initial monotherapy in patients with early PD, and in 2 large, controlled trials (Parkinson's Rasagiline: Efficacy and Safety in the Treatment of "Off," Lasting Effect in Adjunct Therapy With Rasagiline Given Once Daily) as adjunctive treatment in levodopa-treated PD patients with motor fluctuations. Unlike selegiline, rasagiline is an aminoindan derivative with no amphetamine metabolites. A randomized clinical trial is underway to confirm preclinical and preliminary clinical data suggesting rasagiline has disease-modifying effects.

Targeting monoamine oxidase A in advanced prostate cancer.

PubMed

Flamand, Vincent; Zhao, Hongjuan; Peehl, Donna M

2010-11-01

Inhibitors of monoamine oxidase A (MAOA), a mitochondrial enzyme that degrades neurotransmitters including serotonin and norepinephrine, are commonly used to treat neurological conditions including depression. Recently, we and others identified high expression of MAOA in normal basal prostatic epithelium and high-grade primary prostate cancer (PCa). In contrast, MAOA is low in normal secretory prostatic epithelium and low-grade PCa. An irreversible inhibitor of MAOA, clorgyline, induced secretory differentiation in primary cultures of normal basal epithelial cells and high-grade PCa. Furthermore, clorgyline inhibited several oncogenic pathways in PCa cells, suggesting clinical value of MAOA inhibitors as a pro-differentiation and anti-oncogenic therapy for high-risk PCa. Here, we extended our studies to a model of advanced PCa, VCaP cells, which were derived from castration-resistant metastatic PCa and express a high level of MAOA. Growth of VCaP cells in the presence or absence of clorgyline was evaluated in vitro and in vivo. Gene expression changes in response to clorgyline were determined by microarray and validated by quantitative real-time polymerase chain reaction. Treatment with clorgyline in vitro inhibited growth and altered the transcriptional pattern of VCaP cells in a manner consistent with the pro-differentiation and anti-oncogenic effects seen in treated primary PCa cells. Src, beta-catenin, and MAPK oncogenic pathways, implicated in androgen-independent growth and metastasis, were significantly downregulated. Clorgyline treatment of mice bearing VCaP xenografts slowed tumor growth and induced transcriptome changes similar to those noted in vitro. Our results support the possibility that anti-depressant drugs that target MAOA might find a new application in treating PCa.

Monoamine oxidase A and repressor R1 are involved in apoptotic signaling pathway.

PubMed

Ou, Xiao-Ming; Chen, Kevin; Shih, Jean C

2006-07-18

Monoamine oxidase A (MAO A) degrades serotonin, norepinephrine, and dopamine and produces reactive oxygen that may cause neuronal cell death. We have previously reported that a novel transcription factor R1 (RAM2/CDCA7L/JPO2) inhibits the MAO A promoter and enzymatic activities. This study reports the roles of MAO A and R1 in apoptosis and proliferation. We have found that in serum starvation-induced apoptosis, p38 kinase, MAO A, and caspase-3 were increased, whereas Bcl-2 and R1 were reduced. Using a p38 kinase inhibitor, R1 overexpression, and MAO A inhibitor, we have shown that MAO A and R1 are downstream of p38 kinase and Bcl-2, but upstream of caspase-3. Inhibition of MAO A prevents cell apoptosis. This notion was further supported by the finding that serum starvation-induced apoptosis is reduced in cortical brain cells from MAO A-deficient mice compared with WT. In addition, we found that MAO A and R1 are involved in the c-Myc-induced proliferative signaling pathway in the presence of serum. Immunoprecipitation and immunohistochemistry experiments indicate that the oncogene c-Myc colocalizes with R1 and induces R1 gene expression. Using R1 overexpression, R1 small interfering RNA, and a MAO A inhibitor, we found that R1 and MAO A act upstream of cyclin D1 and E2F1. In summary, this study demonstrates the functions of MAO A and its repressor R1 in apoptotic signaling pathways.

The effects of administration of monoamine oxidase-B inhibitors on rat striatal neurone responses to dopamine.

PubMed Central

Berry, M D; Scarr, E; Zhu, M Y; Paterson, I A; Juorio, A V

1994-01-01

1. (-)-Deprenyl has been shown to potentiate rat striatal neurone responses to dopamine agonists at doses not altering dopamine metabolism. Since there are a number of effects of (-)-deprenyl which could result in this phenomenon, we have investigated the effects of MDL 72,145 and Ro 19-6327, whose only common effect with (-)-deprenyl is an inhibition of monoamine oxidase-B (MAO-B), on rat striatal neurone responses to dopamine and on striatal dopamine metabolism. 2. Using in vivo electrophysiology, i.p. injection of either MDL 72,145 or Ro 19-6327 was found to produce a dose-dependent potentiation of striatal neurone responses to dopamine but not gamma-aminobutyric acid. 3. Neurochemical investigations revealed that this occurred at doses (0.25-1 mg kg-1) which, while not affecting levels of dopamine or its metabolites, 3,4-dihydroxyphenylacetic acid or homovanillic acid, did cause a significant, dose-dependent, elevation in striatal levels of the putative neuromodulator, 2-phenylethylamine (PE). 4. Inhibition of PE synthesis by i.p. injection of the aromatic L-amino acid decarboxylase inhibitor, NSD 1015, produced a reversal of the effects of MDL 72,145 and Ro 19-6327. 5. Neurochemical analysis revealed this to occur at a dose of NSD 1015 (10 mg kg-1) selective for reduction of elevated PE levels. 6. These results suggest that PE can act as a neuromodulator of dopaminergic responses and that MAO-B inhibitors may potentiate neuronal responses to dopamine via the indirect mechanism of elevation of PE following MAO-B inhibition. PMID:7889269

CLK-1/Coq7p is a DMQ mono-oxygenase and a new member of the di-iron carboxylate protein family.

PubMed

Rea, S

2001-12-14

Strains of Caenorhabditis elegans mutant for clk-1 exhibit a 20-40% increase in mean lifespan. clk-1 encodes a mitochondrial protein thought to be either an enzyme or regulatory molecule acting within the ubiquinone biosynthesis pathway. Here CLK-1 is shown to be related to the ubiquinol oxidase, alternative oxidase, and belong to the functionally diverse di-iron-carboxylate protein family which includes bacterioferritin and methane mono-oxygenase. Construction and analysis of a homology model indicates CLK-1 is a 2-polyprenyl-3-methyl-6-methoxy-1,4-benzoquinone mono-oxygenase as originally predicted. Analysis of known CLK-1/Coq7p mutations also supports this notion. These findings raise the possibility of developing CLK-1-specific inhibitors to test for lifespan extension in higher organisms.

Monoamine oxidase and head-twitch response in mice. Mechanisms of alpha-methylated substrate derivatives.

PubMed

Nakagawasai, Osamu; Arai, Yuichiro; Satoh, Shin-etsu; Satoh, Nobunori; Neda, Mitsuro; Hozumi, Masato; Oka, Ryusho; Hiraga, Hajime; Tadano, Takeshi

2004-01-01

It is well known that head-twitch response (HTR) in mice represents hallucinations, since administration of lysergic acid diethylamide (LSD) produces hallucinations in humans, and the HTR in mice is induced by administration of LSD as a hallucinogen. The HTR is produced by excitation of 5-hydroxytryptamine (5-HT)2A receptors. In this paper, we review the mechanisms of HTR induced by various drugs such as 5-HT precursor, 5-HT receptor agonist, 5-HT releaser, hallucinogenic compounds, benzodiazepins and cannabinoid. The response induced by HTR-inducers is significantly enhanced by combined treatment with a non-selective form of monoamine oxidase (MAO) inhibitor. Thus, the relationship between MAO activity and HTR caused by these drugs (especially, alpha-methylated analogous compounds which 5-fluoro-alpha-methyltryptamine, 6-fluoro-alpha-methyltryptamine and p-hydroxyamphetamine) is presented in detail.

Salicylic acid inhibits enzymatic browning of fresh-cut Chinese chestnut (Castanea mollissima) by competitively inhibiting polyphenol oxidase.

PubMed

Zhou, Dan; Li, Lin; Wu, Yanwen; Fan, Junfeng; Ouyang, Jie

2015-03-15

The inhibitory effect and associated mechanisms of salicylic acid (SA) on the browning of fresh-cut Chinese chestnut were investigated. Shelled and sliced chestnuts were immersed in different concentrations of an SA solution, and the browning of the chestnut surface and interior were inhibited. The activities of polyphenol oxidase (PPO) and peroxidase (POD) extracted from chestnuts were measured in the presence and absence of SA. SA at concentrations higher than 0.3g/L delayed chestnut browning by significantly inhibiting the PPO activity (P<0.01), and the POD activity was not significantly affected (P>0.05). The binding and inhibition modes of SA with PPO and POD, determined by AUTODOCK 4.2 and Lineweaver-Burk plots, respectively, established SA as a competitive inhibitor of PPO. Copyright © 2014 Elsevier Ltd. All rights reserved.

Hormonal Resistance and Metastasis: ER-coregulator-Src Targeted Therapy

DTIC Science & Technology

2009-09-01

monoamine oxidase inhibitor that blocks LSD1 activity [50] and is approved by FDA for treatment of moderate to severe hypertension. Pargyline is...Research Institute, Princeton, NJ Estrogen receptor (ER) is implicated in breast cancer progression and the majority of the human breast cancers...II. Analysis of PELP1 driven mammary tumors in xenograft as well as in transgenic mouse models revealed increased aromatase expression. PELP1

Hydroxylamine derivatives for regulation of spermine and spermidine metabolism.

PubMed

Khomutov, M A; Weisell, J; Hyvönen, M; Keinänen, T A; Vepsäläinen, J; Alhonen, L; Khomutov, A R; Kochetkov, S N

2013-12-01

The biogenic polyamines spermine, spermidine, and their precursor putrescine are present in micro-to-millimolar concentrations in all cell types and are vitally important for their normal growth. High intracellular content of spermine and spermidine determines the multiplicity of the cellular functions of the polyamines. Many of these functions are not well characterized at the molecular level, ensuring the ongoing development of this field of biochemistry. Tumor cells have elevated polyamine level if compared with normal cells, and this greatly stimulates the search for new opportunities to deplete the intracellular pool of spermine and spermidine resulting in decrease in cell growth and even cell death. O-Substituted hydroxylamines occupy their own place among chemical regulators of the activity of the enzymes of polyamine metabolism. Varying the structure of the alkyl substituent made it possible to obtain within one class of chemical compounds highly effective inhibitors and regulators of the activity of all the enzymes of putrescine, spermine and spermidine metabolism (with the exception of FAD-dependent spermine oxidase and acetylpolyamine oxidase), effectors of the polyamine transport system, and even actively transported in cells "proinhibitor" of ornithine decarboxylase. Some principles for the design of specific inhibitors of these enzymes as well as the peculiarities of cellular effects of corresponding O-substituted hydroxylamines are discussed.

D-amino acid oxidase is expressed in the ventral tegmental area and modulates cortical dopamine

PubMed Central

Betts, Jill F.; Schweimer, Judith V.; Burnham, Katherine E.; Burnet, Philip W. J.; Sharp, Trevor; Harrison, Paul J.

2014-01-01

D-amino acid oxidase (DAO, DAAO) degrades the NMDA receptor co-agonist D-serine, modulating D-serine levels and thence NMDA receptor function. DAO inhibitors are under development as a therapy for schizophrenia, a disorder involving both NMDA receptor and dopaminergic dysfunction. However, a direct role for DAO in dopamine regulation has not been demonstrated. Here, we address this question in two ways. First, using in situ hybridization and immunohistochemistry, we show that DAO mRNA and immunoreactivity are present in the ventral tegmental area (VTA) of the rat, in tyrosine hydroxylase (TH)-positive and -negative neurons, and in glial fibrillary acidic protein (GFAP)-immunoreactive astrocytes. Second, we show that injection into the VTA of sodium benzoate, a DAO inhibitor, increases frontal cortex extracellular dopamine, as measured by in vivo microdialysis and high performance liquid chromatography. Combining sodium benzoate and D-serine did not enhance this effect, and injection of D-serine alone affected dopamine metabolites but not dopamine. These data show that DAO is expressed in the VTA, and suggest that it impacts on the mesocortical dopamine system. The mechanism by which the observed effects occur, and the implications of these findings for schizophrenia therapy, require further study. PMID:24822045

Monoamine Oxidases.

PubMed

Edmondson, Dale E; Binda, Claudia

2018-01-01

Monoamine oxidases A and B (MAO A and B) are mammalian flavoenzymes bound to the outer mitochondrial membrane. They were discovered almost a century ago and they have been the subject of many biochemical, structural and pharmacological investigations due to their central role in neurotransmitter metabolism. Currently, the treatment of Parkinson's disease involves the use of selective MAO B inhibitors such as rasagiline and safinamide. MAO inhibition was shown to exert a general neuroprotective effect as a result of the reduction of oxidative stress produced by these enzymes, which seems to be relevant also in non-neuronal contexts. MAOs were successfully expressed as recombinant proteins in Pichia pastoris, which allowed a thorough biochemical and structural characterization. These enzymes are characterized by a globular water-soluble main body that is anchored to the mitochondrial membrane through a C-terminal α-helix, similar to other bitopic membrane proteins. In both MAO A and MAO B the enzyme active site consists of a hydrophobic cavity lined by residues that are conserved in the two isozymes, except for few details that determine substrate and inhibitor specificity. In particular, human MAO B features a dual-cavity active site whose conformation depends on the size of the bound ligand. This article provides a comprehensive and historical review of MAOs and the state-of-the-art of these enzymes as membrane drug targets.

Contribution of aldosterone to cardiovascular and renal inflammation and fibrosis

PubMed Central

Brown, Nancy J.

2014-01-01

The steroid hormone aldosterone regulates sodium and potassium homeostasis. Aldosterone and activation of the mineralocorticoid receptor also causes inflammation and fibrosis of the heart, fibrosis and remodelling of blood vessels and tubulointerstitial fibrosis and glomerular injury in the kidney. Aldosterone and mineralocorticoid-receptor activation initiate an inflammatory response by increasing the generation of reactive oxygen species by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase and mitochondria. High salt intake potentiates these effects, in part by activating the Rho family member Rac1, a regulatory subunit of reduced NADPH oxidase that activates the mineralocorticoid receptor. Studies in mice in which the mineralocorticoid receptor has been deleted from specific cell types suggest a key role for macrophages in promoting inflammation and fibrosis. Aldosterone can exert mineralocorticoid-receptor-independent effects via the angiotensin II receptor and via G-protein-coupled receptor 30. Mineralocorticoid-receptor antagonists are associated with decreased mortality in patients with heart disease and show promise in patients with kidney injury, but can elevate serum potassium concentration. Studies in rodents genetically deficient in aldosterone synthase or treated with a pharmacological aldosterone-synthase inhibitor are providing insight into the relative contribution of aldosterone compared with the contribution of mineralocorticoid-receptor activation in inflammation, fibrosis, and injury. Aldosterone-synthase inhibitors are under development in humans. PMID:23774812

Aromatic Regions Govern the Recognition of NADPH Oxidase Inhibitors as Diapocynin and its Analogues.

PubMed

Macías Pérez, Martha E; Hernández Rodríguez, Maricarmen; Cabrera Pérez, Laura C; Fragoso-Vázquez, M Jonathan; Correa-Basurto, José; Padilla-Martínez, Itzia I; Méndez Luna, David; Mera Jiménez, Elvia; Flores Sandoval, César; Tamay Cach, Feliciano; Rosales-Hernández, Martha C

2017-10-01

Oxidative stress is related to the pathogenesis and progress of several human diseases. NADPH oxidase (NOX), and mainly the NOX2 isoform, produces superoxide anions (O 2 • - ). To date, it is known that NOX2 can be inhibited by preventing the assembly of its subunits, p47phox and p22phox. In this work, we analyzed the binding to NOX2 of the apocynin dimer, diapocynin (C1), a known NOX2 inhibitor, and of 18 designed compounds (C2-C19) which have chemical relationships to C1, by in silico methods employing a p47phox structure from the Protein Data Bank (PDB code: 1WLP). C1 and six of the designed compounds were recognized in the region where p22phox binds to p47phox and makes π-π interactions principally with W193, W263, and Y279, which form an aromatic-rich region. C8 was chosen as the best compound according to the in silico studies and was synthesized and evaluated in vitro. C8 was able to prevent the production of reactive oxygen species (ROS) similar to C1. In conclusion, targeting the aromatic region of p47phox through π-interactions is important for inhibiting NOX activity. © 2017 Deutsche Pharmazeutische Gesellschaft.

Synthesis of Amide and Ester Derivatives of Cinnamic Acid and Its Analogs: Evaluation of Their Free Radical Scavenging and Monoamine Oxidase and Cholinesterase Inhibitory Activities.

PubMed

Takao, Koichi; Toda, Kazuhiro; Saito, Takayuki; Sugita, Yoshiaki

2017-01-01

A series of cinnamic acid derivatives, amides (1-12) and esters (13-22), were synthesized, and structure-activity relationships for antioxidant activity, and monoamine oxidases (MAO) A and B, acetylcholinesterase, and butyrylcholinesterase (BChE) inhibitory activities were analyzed. Among the synthesized compounds, compounds 1-10, 12-18, and rosmarinic acid (23), which contained catechol, o-methoxyphenol or 5-hydroxyindole moieties, showed potent 1,1-diphenyl-2-picrylhydrazyl (DPPH) free radical scavenging activity. Compounds 9-11, 15, 17-22 showed potent and selective MAO-B inhibitory activity. Compound 20 was the most potent inhibitor of MAO-B. Compounds 18 and 21 showed moderate BChE inhibitory activity. In addition, compound 18 showed potent antioxidant activity and MAO-B inhibitory activity. In a comparison of the cinnamic acid amides and esters, the amides exhibited more potent DPPH free radical scavenging activity, while the esters showed stronger inhibitory activities against MAO-B and BChE. These results suggested that cinnamic acid derivatives such as compound 18, p-coumaric acid 3,4-dihydroxyphenethyl ester, and compound 20, p-coumaric acid phenethyl ester, may serve as lead compounds for the development of novel MAO-B inhibitors and candidate lead compounds for the prevention or treatment of Alzheimer's disease.

Substituted thieno[2,3-b]thiophenes and related congeners: Synthesis, β-glucuronidase inhibition activity, crystal structure, and POM analyses.

PubMed

Mabkhot, Yahia Nasser; Barakat, Assem; Yousuf, Sammer; Choudhary, M Iqbal; Frey, Wolfgang; Ben Hadda, Taibi; Mubarak, Mohammad S

2014-12-01

A series of 15 novel compounds incorporating the thieno[2,3-b]thiophene moiety were synthesized. The chemical structures of these compounds were deduced from elemental analyses, (1)H NMR, (13)C NMR, and ESI-mass spectral data. The enzyme inhibition potential of these compounds was evaluated, in vitro, against β-glucuronidase, xanthine oxidase, and α-chymotrypsin enzymes. The cytotoxicity was evaluated by a cell viability assay utilizing the 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) dye. Among the compounds tested, compound 3 was the most potent β-glucuronidase inhibitor with an IC50 value of 0.9 ± 0.0138 μM; it was much more active than the standard, d-saccharic acid 1,4-lactone (IC50=45.75 ± 2.16 μM). Compound 12, on the other hand, was the most potent as a xanthine oxidase inhibitor with an IC50 of 14.4 ± 1.2 μM. With the characterization of their mechanism of action and with further testing, these compounds could be useful candidates as anticancer drugs. In addition, the newly synthesized compounds were subjected to POM analyses to get insights about their degree of their toxicity. Copyright © 2014 Elsevier Ltd. All rights reserved.

Acute, Sub-lethal Cyanide Poisoning in Mice is Ameliorated by Nitrite Alone: Complications Arising from Concomitant Administration of Nitrite and Thiosulfate as an Antidotal Combination

PubMed Central

Cambal, Leah K.; Swanson, Megan R.; Yuan, Quan; Weitz, Andrew C.; Li, Hui-Hua; Pitt, Bruce R.; Pearce, Linda L.; Peterson, Jim

2011-01-01

Sodium nitrite alone is shown to ameliorate sub-lethal cyanide toxicity in mice when given from ~1 hour before until 20 minutes after the toxic dose as demonstrated by the recovery of righting ability. An optimum dose (12 mg/kg) was determined to significantly relieve cyanide toxicity (5.0 mg/kg) when administered to mice intraperitoneally. Nitrite so administered was shown to rapidly produce NO in the bloodsteam as judged by the dose dependent appearance of EPR signals attributable to nitrosylhemoglobin and methemoglobin. It is argued that antagonism of cyanide inhibition of cytochrome c oxidase by NO is the crucial antidotal activity rather than the methemoglobin-forming action of nitrite. Concomitant addition of sodium thiosulfate to nitrite-treated blood resulted in the detection of sulfidomethemoblobin by EPR spectroscopy. Sulfide is a product of thiosulfate hydrolysis and, like cyanide, is known to be a potent inhibitor of cytochrome c oxidase; the effects of the two inhibitors being essentially additive under standard assay conditions, rather than dominated by either one. The findings afford a plausible explanation for an observed detrimental effect in mice associated with the use of the standard nitrite-thiosulfate combination therapy at sub-lethal levels of cyanide intoxication. PMID:21534623

Direct effect of Taxol on free radical formation and mitochondrial permeability transition.

PubMed

Varbiro, G; Veres, B; Gallyas, F; Sumegi, B

2001-08-15

To elucidate the potential role of mitochondria in Taxol-induced cytotoxicity, we studied its direct mitochondrial effects. In Percoll-gradient purified liver mitochondria, Taxol induced large amplitude swelling in a concentration-dependent manner in the microM range. Opening of the permeability pore was also confirmed by the access of mitochondrial matrix enzymes for membrane impermeable substrates in Taxol-treated mitochondria. Taxol induced the dissipation of mitochondrial membrane potential (DeltaPsi) determined by Rhodamine123 release and induced the release of cytochrome c from the intermembrane space. All these effects were inhibited by 2.5 microM cyclosporine A. Taxol significantly increased the formation of reactive oxygen species (ROS) in both the aqueous and the lipid phase as determined by dihydrorhodamine123 and resorufin derivative. Cytochrome oxidase inhibitor CN(-), azide, and NO abrogated the Taxol-induced mitochondrial ROS formation while inhibitors of the other respiratory complexes and cyclosporine A had no effect. We confirmed that the Taxol-induced collapse of DeltaPsi and the induction of ROS production occurs in BRL-3A cells. In conclusion, Taxol-induced adenine nucleotide translocase-cyclophilin complex mediated permeability transition, and cytochrome oxidase mediated ROS production. Because both cytochrome c release and mitochondrial ROS production can induce suicide pathways, the direct mitochondrial effects of Taxol may contribute to its cytotoxicity.

Binding of Rasagiline-related Inhibitors to Human Monoamine Oxidases

PubMed Central

Binda, Claudia; Hubálek, Frantisek; Li, Min; Herzig, Yaacov; Sterling, Jeffrey; Edmondson, Dale E.; Mattevi, Andrea

2008-01-01

Monoamine oxidases A and B (MAO A and B) catalyze neurotransmitters degradation and represent drug targets for the treatment of neurodegenerative disorders. Rasagiline is an irreversible, MAO B-selective inhibitor that has been approved as a novel anti-Parkinson’s drug. In this study we investigate the inhibition of recombinant human MAO A and MAO B by several rasagiline analogues. Different substituents added onto the rasagiline scaffold alter the binding affinity depending on the position on the aminoindan ring and on the size of the substituent. Compounds with a hydroxyl group on either the C4 or the C6 atom inhibit both isozymes, whereas a bulkier substituent such as a carbamate is tolerated only at the C4 position. The 1.7 Å crystal structure of MAO B in complex with 4-(N-methyl-N-ethyl-carbamoyloxy)-N-methyl-N-propargyl-1(R)-aminoindan shows that the binding mode is similar to that of rasagiline with the carbamate moiety occupying the entrance cavity space. 1(R)-aminoindan, the major metabolic product of rasagiline, and its analogues reversibly inhibit both MAO A and MAO B. The crystal structure of N-methyl-1(R)-aminoindan bound to MAO B shows that its aminoindan ring adopts a different orientation compared to that of rasagiline. PMID:16366596

PAM-OBG: A monoamine oxidase B specific prodrug that inhibits MGMT and generates DNA interstrand crosslinks, potentiating temozolomide and chemoradiation therapy in intracranial glioblastoma

PubMed Central

Sharpe, Martyn A.; Raghavan, Sudhir; Baskin, David S.

2018-01-01

Via extensive analyses of genetic databases, we have characterized the DNA-repair capacity of glioblastoma with respect to patient survival. In addition to elevation of O6-methylguanine DNA methyltransferase (MGMT), down-regulation of three DNA repair pathways; canonical mismatch repair (MMR), Non-Homologous End-Joining (NHEJ), and Homologous Recombination (HR) are correlated with poor patient outcome. We have designed and tested both in vitro and in vivo, a monoamine oxidase B (MAOB) specific prodrug, PAM-OBG, that is converted by glioma MAOB into the MGMT inhibitor O6-benzylguanine (O6BG) and the DNA crosslinking agent acrolein. In cultured glioma cells, we show that PAM-OBG is converted to O6BG, inhibiting MGMT and sensitizing cells to DNA alkylating agents such as BCNU, CCNU, and Temozolomide (TMZ). In addition, we demonstrate that the acrolein generated is highly toxic in glioma treated with an inhibitor of Nucleotide Excision Repair (NER). In mouse intracranial models of primary human glioma, we show that PAM-OBG increases survival of mice treated with either BCNU or CCNU by a factor of six and that in a chemoradiation model utilizing six rounds of TMZ/2Gy radiation, pre-treatment with PAM-OBG more than doubled survival time. PMID:29844863

Monoamine oxidase inactivation: from pathophysiology to therapeutics.

PubMed

Bortolato, Marco; Chen, Kevin; Shih, Jean C

2008-01-01

Monoamine oxidases (MAOs) A and B are mitochondrial bound isoenzymes which catalyze the oxidative deamination of dietary amines and monoamine neurotransmitters, such as serotonin, norepinephrine, dopamine, beta-phenylethylamine and other trace amines. The rapid degradation of these molecules ensures the proper functioning of synaptic neurotransmission and is critically important for the regulation of emotional behaviors and other brain functions. The byproducts of MAO-mediated reactions include several chemical species with neurotoxic potential, such as hydrogen peroxide, ammonia and aldehydes. As a consequence, it is widely speculated that prolonged excessive activity of these enzymes may be conducive to mitochondrial damages and neurodegenerative disturbances. In keeping with these premises, the development of MAO inhibitors has led to important breakthroughs in the therapy of several neuropsychiatric disorders, ranging from mood disorders to Parkinson's disease. Furthermore, the characterization of MAO knockout (KO) mice has revealed that the inactivation of this enzyme produces a number of functional and behavioral alterations, some of which may be harnessed for therapeutic aims. In this article, we discuss the intriguing hypothesis that the attenuation of the oxidative stress induced by the inactivation of either MAO isoform may contribute to both antidepressant and antiparkinsonian actions of MAO inhibitors. This possibility further highlights MAO inactivation as a rich source of novel avenues in the treatment of mental disorders.

PAM-OBG: A monoamine oxidase B specific prodrug that inhibits MGMT and generates DNA interstrand crosslinks, potentiating temozolomide and chemoradiation therapy in intracranial glioblastoma.

PubMed

Sharpe, Martyn A; Raghavan, Sudhir; Baskin, David S

2018-05-08

Via extensive analyses of genetic databases, we have characterized the DNA-repair capacity of glioblastoma with respect to patient survival. In addition to elevation of O 6 -methylguanine DNA methyltransferase (MGMT), down-regulation of three DNA repair pathways; canonical mismatch repair (MMR), Non-Homologous End-Joining (NHEJ), and Homologous Recombination (HR) are correlated with poor patient outcome. We have designed and tested both in vitro and in vivo , a monoamine oxidase B (MAOB) specific prodrug, PAM-OBG, that is converted by glioma MAOB into the MGMT inhibitor O 6 -benzylguanine (O 6 BG) and the DNA crosslinking agent acrolein. In cultured glioma cells, we show that PAM-OBG is converted to O 6 BG, inhibiting MGMT and sensitizing cells to DNA alkylating agents such as BCNU, CCNU, and Temozolomide (TMZ). In addition, we demonstrate that the acrolein generated is highly toxic in glioma treated with an inhibitor of Nucleotide Excision Repair (NER). In mouse intracranial models of primary human glioma, we show that PAM-OBG increases survival of mice treated with either BCNU or CCNU by a factor of six and that in a chemoradiation model utilizing six rounds of TMZ/2Gy radiation, pre-treatment with PAM-OBG more than doubled survival time.

Hypochlorous acid regulates neutrophil extracellular trap release in humans

PubMed Central

Palmer, L J; Cooper, P R; Ling, M R; Wright, H J; Huissoon, A; Chapple, I L C

2012-01-01

Neutrophil extracellular traps (NETs) comprise extracellular chromatin and granule protein complexes that immobilize and kill bacteria. NET release represents a recently discovered, novel anti-microbial strategy regulated non-exclusively by nicotinamide adenine dinucleotide phosphate (NADPH) oxidase generation of reactive oxygen intermediates (ROIs), particularly hydrogen peroxide. This study aimed to characterize the role of ROIs in the process of NET release and to identify the dominant ROI trigger. We employed various enzymes, inhibitors and ROIs to record their effect fluorometrically on in vitro NET release by human peripheral blood neutrophils. Treatment with exogenous superoxide dismutase (SOD) supported the established link between hydrogen peroxide and NET production. However, treatment with myeloperoxidase inhibitors and direct addition of hypochlorous acid (HOCl; generated in situ from sodium hypochlorite) established that HOCl was a necessary and sufficient ROI for NET release. This was confirmed by the ability of HOCl to stimulate NET release in chronic granulomatous disease (CGD) patient neutrophils which, due to the lack of a functional NADPH oxidase, also lack the capacity for NET release in response to classical stimuli. Moreover, the exogenous addition of taurine, abundantly present within the neutrophil cytosol, abrogated NET production stimulated by phorbol myristate acetate (PMA) and HOCl, providing a novel mode of cytoprotection by taurine against oxidative stress by taurine. PMID:22236002

Investigation of the interaction between benzaldehyde thiosemicarbazone compounds and xanthine oxidase

NASA Astrophysics Data System (ADS)

Li, Mengrong; Yu, Yanying; Liu, Jing; Chen, Zelu; Cao, Shuwen

2018-05-01

A series of substituted benzaldehyde thiosemicarbazide compounds (1-7) were synthesized as xanthine oxidase (XO) inhibitors, and the interactions between substituted benzaldehyde thiosemicarbazide compounds (1-7) and XO were studied by ultraviolet spectroscopy, fluorescence spectroscopy, and molecular docking. It was found that the hydrogen bond and hydrophobicity were the main interactions between substituted benzaldehyde thiosemicarbazide compounds and XO, and introducing sbnd OH at the para position of the benzene ring and a Ph- or Me-group at the amino terminal of compound 4 increased the modifier's inhibitory activity. The results suggest that the newly introduced benzene ring interacted with the hydrophobic cavity of XO by means of the π-π stacking force between the newly introduced benzene ring and the aromatic amino acid residues, such as the Phe residue, which greatly increased the modifier's inhibitory activity. We conclude that introducing the Ph-group at the amino terminal of compound 4 and the sbnd OH group at the para position of the benzene ring was a good route to obtain novel XO inhibitors. Fluorescence spectroscopy assisted by 8-anilino-1-naphthalenesulfonic acid fluorescence probing and molecular docking were helpful for achieving a preliminary and relatively clear understanding of the interactions between target compounds and XO, which deserve further study.

The NADPH oxidase inhibitor apocynin (acetovanillone) induces oxidative stress

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

Riganti, Chiara; Costamagna, Costanzo; Bosia, Amalia

Apocynin (acetovanillone) is often used as a specific inhibitor of NADPH oxidase. In N11 glial cells, apocynin induced, in a dose-dependent way, a significant increase of both malonyldialdehyde level (index of lipid peroxidation) and lactate dehydrogenase release (index of a cytotoxic effect). Apocynin evoked also, in a significant way, an increase of H{sub 2}O{sub 2} concentration and a decrease of the intracellular glutathione/glutathione disulfide ratio, accompanied by augmented efflux of glutathione and glutathione disulfide. Apocynin induced the activation of both pentose phosphate pathway and tricarboxylic acid cycle, which was blocked when the cells were incubated with glutathione together with apocynin.more » The cell incubation with glutathione prevented also the apocynin-induced increase of malonyldialdehyde generation and lactate dehydrogenase leakage. Apocynin exerted an oxidant effect also in a cell-free system: indeed, in aqueous solution, it evoked a faster oxidation of the thiols glutathione and dithiothreitol, and elicited the generation of reactive oxygen species, mainly superoxide anions. Our results suggest that apocynin per se can induce an oxidative stress and exert a cytotoxic effect in N11 cells and other cell types, and that some effects of apocynin in in vitro and in vivo experimental models should be interpreted with caution.« less

Stimulation of the cardiac myocyte Na+-K+ pump due to reversal of its constitutive oxidative inhibition

PubMed Central

Chia, Karin K. M.; Liu, Chia-Chi; Hamilton, Elisha J.; Garcia, Alvaro; Fry, Natasha A.; Hannam, William; Figtree, Gemma A.

2015-01-01

Protein kinase C can activate NADPH oxidase and induce glutathionylation of the β1-Na+-K+ pump subunit, inhibiting activity of the catalytic α-subunit. To examine if signaling of nitric oxide-induced soluble guanylyl cyclase (sGC)/cGMP/protein kinase G can cause Na+-K+ pump stimulation by counteracting PKC/NADPH oxidase-dependent inhibition, cardiac myocytes were exposed to ANG II to activate NADPH oxidase and inhibit Na+-K+ pump current (Ip). Coexposure to 3-(5′-hydroxymethyl-2′-furyl)-1-benzylindazole (YC-1) to stimulate sGC prevented the decrease of Ip. Prevention of the decrease was abolished by inhibition of protein phosphatases (PP) 2A but not by inhibition of PP1, and it was reproduced by an activator of PP2A. Consistent with a reciprocal relationship between β1-Na+-K+ pump subunit glutathionylation and pump activity, YC-1 decreased ANG II-induced β1-subunit glutathionylation. The decrease induced by YC-1 was abolished by a PP2A inhibitor. YC-1 decreased phosphorylation of the cytosolic p47phox NADPH oxidase subunit and its coimmunoprecipitation with the membranous p22phox subunit, and it decreased O2·−-sensitive dihydroethidium fluorescence of myocytes. Addition of recombinant PP2A to myocyte lysate decreased phosphorylation of p47phox indicating the subunit could be a substrate for PP2A. The effects of YC-1 to decrease coimmunoprecipitation of p22phox and p47phox NADPH oxidase subunits and decrease β1-Na+-K+ pump subunit glutathionylation were reproduced by activation of nitric oxide-dependent receptor signaling. We conclude that sGC activation in cardiac myocytes causes a PP2A-dependent decrease in NADPH oxidase activity and a decrease in β1 pump subunit glutathionylation. This could account for pump stimulation with neurohormonal oxidative stress expected in vivo. PMID:26084308

A Prenylated p47phox-p67phox-Rac1 Chimera Is a Quintessential NADPH Oxidase Activator

PubMed Central

Mizrahi, Ariel; Berdichevsky, Yevgeny; Casey, Patrick J.; Pick, Edgar

2010-01-01

The superoxide-generating NADPH oxidase complex of resting phagocytes includes cytochrome b559, a membrane-associated heterodimer composed of two subunits (Nox2 and p22phox), and four cytosolic proteins (p47phox, p67phox, Rac, and p40phox). Upon stimulation, the cytosolic components translocate to the membrane, as the result of a series of interactions among the cytosolic components and among the cytosolic components and cytochrome b559 and its phospholipid environment. We described the construction of a tripartite chimera (trimera) consisting of strategic domains of p47phox, p67phox, and Rac1, in which interactions among cytosolic components were replaced by fusion (Berdichevsky, Y., Mizrahi, A., Ugolev, Y., Molshanski-Mor, S., and Pick, E. (2007) J. Biol. Chem. 282, 22122–22139). We now fused green fluorescent protein (GFP) to the N terminus of the trimera and found the following. 1) The GFP-p47phox-p67phox-Rac1 trimera activates the oxidase in amphiphile-dependent and -independent (anionic phospholipid-enriched membrane) cell-free systems. 2) Geranylgeranylation of the GFP-trimera makes it a potent oxidase activator in unmodified (native) membranes and in the absence of amphiphile. 3) Prenylated GFP-trimera binds spontaneously to native membranes (as assessed by gel filtration and in-line fluorometry), forming a tight complex capable of NADPH-dependent, activator-independent superoxide production at rates similar to those measured in canonical cell-free systems. 4) Prenylation of the GFP-trimera supersedes completely the dependence of oxidase activation on the p47phox phox homology domain and, partially, on the Rac1 polybasic domain, but the requirement for Trp193 in p47phox persists. Prenylated GFP-p47phox-p67phox-Rac1 trimera acts as a quintessential single molecule oxidase activator of potential use in high throughput screening of inhibitors. PMID:20529851

Globular adiponectin inhibits ethanol-induced reactive oxygen species production through modulation of NADPH oxidase in macrophages: involvement of liver kinase B1/AMP-activated protein kinase pathway.

PubMed

Kim, Mi Jin; Nagy, Laura E; Park, Pil-Hoon

2014-09-01

Adiponectin, an adipokine predominantly secreted from adipocytes, has been shown to play protective roles against chronic alcohol consumption. Although excessive reactive oxygen species (ROS) production in macrophages is considered one of the critical events for ethanol-induced damage in various target tissues, the effect of adiponectin on ethanol-induced ROS production is not clearly understood. In the present study, we investigated the effect of globular adiponectin (gAcrp) on ethanol-induced ROS production and the potential mechanisms underlying these effects of gAcrp in macrophages. Here we demonstrated that gAcrp prevented ethanol-induced ROS production in both RAW 264.7 macrophages and primary murine peritoneal macrophages. Globular adiponectin also inhibited ethanol-induced activation of NADPH oxidase. In addition, gAcrp suppressed ethanol-induced increase in the expression of NADPH oxidase subunits, including Nox2 and p22(phox), via modulation of nuclear factor-κB pathway. Furthermore, pretreatment with compound C, a selective inhibitor of AMPK, or knockdown of AMPK by small interfering RNA restored suppression of ethanol-induced ROS production and Nox2 expression by gAcrp. Finally, we found that gAcrp treatment induced phosphorylation of liver kinase B1 (LKB1), an upstream signaling molecule mediating AMPK activation. Knockdown of LKB1 restored gAcrp-suppressed Nox2 expression, suggesting that LKB1/AMPK pathway plays a critical role in the suppression of ethanol-induced ROS production and activation of NADPH oxidase by gAcrp. Taken together, these results demonstrate that globular adiponectin prevents ethanol-induced ROS production, at least in part, via modulation of NADPH oxidase in macrophages. Further, LKB1/AMPK axis plays an important role in the suppression of ethanol-induced NADPH oxidase activation by gAcrp in macrophages. Copyright © 2014 by The American Society for Pharmacology and Experimental Therapeutics.

Structure of alpha-glycerophosphate oxidase from Streptococcus sp.: a template for the mitochondrial alpha-glycerophosphate dehydrogenase.

PubMed

Colussi, Timothy; Parsonage, Derek; Boles, William; Matsuoka, Takeshi; Mallett, T Conn; Karplus, P Andrew; Claiborne, Al

2008-01-22

The FAD-dependent alpha-glycerophosphate oxidase (GlpO) from Enterococcus casseliflavus and Streptococcus sp. was originally studied as a soluble flavoprotein oxidase; surprisingly, the GlpO sequence is 30-43% identical to those of the alpha-glycerophosphate dehydrogenases (GlpDs) from mitochondrial and bacterial sources. The structure of a deletion mutant of Streptococcus sp. GlpO (GlpODelta, lacking a 50-residue insert that includes a flexible surface region) has been determined using multiwavelength anomalous dispersion data and refined at 2.3 A resolution. Using the GlpODelta structure as a search model, we have also determined the intact GlpO structure, as refined at 2.4 A resolution. The first two domains of the GlpO fold are most closely related to those of the flavoprotein glycine oxidase, where they function in FAD binding and substrate binding, respectively; the GlpO C-terminal domain consists of two helix bundles and is not closely related to any known structure. The flexible surface region in intact GlpO corresponds to a segment of missing electron density that links the substrate-binding domain to a betabetaalpha element of the FAD-binding domain. In accordance with earlier biochemical studies (stabilizations of the covalent FAD-N5-sulfite adduct and p-quinonoid form of 8-mercapto-FAD), Ile430-N, Thr431-N, and Thr431-OG are hydrogen bonded to FAD-O2alpha in GlpODelta, stabilizing the negative charge in these two modified flavins and facilitating transfer of a hydride to FAD-N5 (from Glp) as well. Active-site overlays with the glycine oxidase-N-acetylglycine and d-amino acid oxidase-d-alanine complexes demonstrate that Arg346 of GlpODelta is structurally equivalent to Arg302 and Arg285, respectively; in both cases, these residues interact directly with the amino acid substrate or inhibitor carboxylate. The structural and functional divergence between GlpO and the bacterial and mitochondrial GlpDs is also discussed.

Production and actions of superoxide in the renal medulla.

PubMed

Zou, A P; Li, N; Cowley, A W

2001-02-01

The present study characterized the biochemical pathways responsible for superoxide (O(2)(-.)) production in different regions of the rat kidney and determined the role of O(2)(-.)in the control of renal medullary blood flow (MBF) and renal function. By use of dihydroethidium/DNA fluorescence spectrometry with microtiter plates, the production of O(2)(-. )was monitored when tissue homogenate from different kidney regions was incubated with substrates for the major O(2)(-.)-producing enzymes, such as NADH/NADPH oxidase, xanthine oxidase, and mitochondrial respiratory chain enzymes. The production of O(2)(-. )via NADH oxidase was greater (P<0.05) in the renal cortex and outer medulla (OM) than in the papilla. The mitochondrial enzyme activity for O(2)(-.)production was higher (P<0.05) in the OM than in the cortex and papilla. Compared with NADH oxidase and mitochondrial enzymes, xanthine oxidase and NADPH oxidase produced much less O(2)(-. )in the kidney under this condition. Overall, the renal OM exhibited the greatest enzyme activities for O(2)(-.)production. In anesthetized rats, renal medullary interstitial infusion of a superoxide dismutase inhibitor, diethyldithiocarbamate, markedly decreased renal MBF and sodium excretion. Diethyldithiocarbamate (5 mg/kg per minute by renal medullary interstitial infusion [RI]) reduced the renal medullary laser-Doppler flow signal from 0.6+/-0.04 to 0.4+/-0.03 V, a reduction of 33%, and both urine flow and sodium excretion decreased by 49%. In contrast, a membrane-permeable superoxide dismutase mimetic, 4-hydroxytetramethyl-piperidine-1-oxyl (TEMPOL, 30 micromol/kg per minute RI) increased MBF and sodium excretion by 34% and 69%, respectively. These effects of TEMPOL on renal MBF and sodium excretion were not altered by pretreatment with N(G)-nitro-L-arginine methyl ester (10 microgram/kg per minute RI). We conclude that (1) renal medullary O(2)(-. )is primarily produced in the renal OM; (2) both NADH oxidase and mitochondrial enzymes are responsible for the O(2)(-.)production in this kidney region; and (3) O(2)(-. )exerts a tonic regulatory action on renal MBF.

Role of xanthine oxidoreductase and NAD(P)H oxidase in endothelial superoxide production in response to oscillatory shear stress

NASA Technical Reports Server (NTRS)

McNally, J. Scott; Davis, Michael E.; Giddens, Don P.; Saha, Aniket; Hwang, Jinah; Dikalov, Sergey; Jo, Hanjoong; Harrison, David G.

2003-01-01

Oscillatory shear stress occurs at sites of the circulation that are vulnerable to atherosclerosis. Because oxidative stress contributes to atherosclerosis, we sought to determine whether oscillatory shear stress increases endothelial production of reactive oxygen species and to define the enzymes responsible for this phenomenon. Bovine aortic endothelial cells were exposed to static, laminar (15 dyn/cm2), and oscillatory shear stress (+/-15 dyn/cm2). Oscillatory shear increased superoxide (O2.-) production by more than threefold over static and laminar conditions as detected using electron spin resonance (ESR). This increase in O2*- was inhibited by oxypurinol and culture of endothelial cells with tungsten but not by inhibitors of other enzymatic sources. Oxypurinol also prevented H2O2 production in response to oscillatory shear stress as measured by dichlorofluorescin diacetate and Amplex Red fluorescence. Xanthine-dependent O2*- production was increased in homogenates of endothelial cells exposed to oscillatory shear stress. This was associated with decreased xanthine dehydrogenase (XDH) protein levels and enzymatic activity resulting in an elevated ratio of xanthine oxidase (XO) to XDH. We also studied endothelial cells lacking the p47phox subunit of the NAD(P)H oxidase. These cells exhibited dramatically depressed O2*- production and had minimal XO protein and activity. Transfection of these cells with p47phox restored XO protein levels. Finally, in bovine aortic endothelial cells, prolonged inhibition of the NAD(P)H oxidase with apocynin decreased XO protein levels and prevented endothelial cell stimulation of O2*- production in response to oscillatory shear stress. These data suggest that the NAD(P)H oxidase maintains endothelial cell XO levels and that XO is responsible for increased reactive oxygen species production in response to oscillatory shear stress.

Safflor yellow B suppresses angiotensin II-mediated human umbilical vein cell injury via regulation of Bcl-2/p22{sup phox} expression

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

Wang, Chaoyun; He, Yanhao; Department of Pharmacology, Xi'an Jiaotong University School of Medicine, Key Laboratory of Environment and Genes Related to Disease, Ministry of Education, Xi'an, Shaanxi 710061

Intracellular reactive oxygen species (ROS) are derived from nicotinamide adenine dinucleotide phosphate (NADPH) oxidase. Angiotensin II (Ang II) can cause endothelial dysfunction by promoting intracellular ROS generation. Safflor yellow B (SYB) effectively inhibits ROS generation by upregulating Bcl-2 expression. In this study, we examined the effects of SYB on Ang II-induced injury to human umbilical vein endothelial cells (HUVECs), and elucidated the roles of NADPH oxidase and Bcl-2. We treated cultured HUVECs with Ang II, SYB, and Bcl-2 siRNA, and determined NADPH oxidase activity and ROS levels. Furthermore, cellular and mitochondrial physiological states were evaluated, and the expression levels ofmore » target proteins were analyzed. Ang II significantly enhanced intracellular ROS levels, caused mitochondrial membrane dysfunction, and decreased cell viability, leading to apoptosis. This was associated with increased expression of AT1R and p22{sup phox}, increased NADPH oxidase activity, and an increased ratio of Bax/Bcl-2, leading to decreases in antioxidant enzyme activities, which were further strengthened after blocking Bcl-2. Compared to Ang II treatment alone, co-treatment with SYB significantly reversed HUVEC injury. Taken together, these results demonstrate that SYB could significantly protect endothelial cells from Ang II-induced cell damage, and that it does so by upregulating Bcl-2 expression and inhibiting ROS generation. - Highlights: • Angiotensin II depresses mitochondria physiological function. • Angiotensin II activates NADPH oxidase via up-regulating expresion of p22{sup phox}. • Bcl-2 plays a pivotal role in improving mitochondria function and regulates ROS level. • Inhibitor of Bcl-2 promotes angiotensin II mediated HUVEC injury. • SYB attenuates angiotensin II mediated HUVEC injury via up regulating Bcl-2 expression.« less

Inhibition of arsenic induced-rat liver injury by grape seed exact through suppression of NADPH oxidase and TGF-{beta}/Smad activation

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

Pan Xinjuan; Dai Yujie; Li Xing

2011-08-01

Chronic arsenic exposure induces oxidative damage to liver leading to liver fibrosis. We aimed to define the effect of grape seed extract (GSE), an antioxidant dietary supplement, on arsenic-induced liver injury. First, Male Sprague-Dawley rats were exposed to a low level of arsenic in drinking water (30 ppm) with or without GSE (100 mg/kg, every other day by oral gavage) for 12 months and the effect of GSE on arsenic-induced hepatotoxicity was examined. The results from this study revealed that GSE co-treatment significantly attenuated arsenic-induced low antioxidant defense, oxidative damage, proinflammatory cytokines and fibrogenic genes. Moreover, GSE reduced arsenic-stimulated Smad2/3more » phosphorylation and protein levels of NADPH oxidase subunits (Nox2, Nox4 and p47phox). Next, we explored the molecular mechanisms underlying GSE inhibition of arsenic toxicity using cultured rat hepatic stellate cells (HSCs). From the in vitro study, we found that GSE dose-dependently reduced arsenic-stimulated ROS production and NADPH oxidase activities. Both NADPH oxidases flavoprotein inhibitor DPI and Nox4 siRNA blocked arsenic-induced ROS production, whereas Nox4 overexpression suppressed the inhibitory effects of GSE on arsenic-induced ROS production and NADPH oxidase activities, as well as expression of TGF-{beta}1, type I procollagen (Coll-I) and {alpha}-smooth muscle actin ({alpha}-SMA) mRNA. We also observed that GSE dose-dependently inhibited TGF-{beta}1-induced transactivation of the TGF-{beta}-induced smad response element p3TP-Lux, and that forced expression of Smad3 attenuated the inhibitory effects of GSE on TGF-{beta}1-induced mRNA expression of Coll-I and {alpha}-SMA. Collectively, GSE could be a potential dietary therapeutic agent for arsenic-induced liver injury through suppression of NADPH oxidase and TGF-{beta}/Smad activation. - Research Highlights: > GSE attenuated arsenic-induced low antioxidant defense, oxidative damage, proinflammatory cytokines and fibrogenic genes. > GSE reduced arsenic-mediated Smad2/3 phosphorylation and NADPH oxidase subunits (Nox2, Nox4 and p47phox). > Beneficial effects of GSE on As-induced liver injury was via inhibition of NADPH oxidase and TGF-{beta}/Smad activation.« less

Preferential inhibition of xanthine oxidase by 2-amino-6-hydroxy-8-mercaptopurine and 2-amino-6-purine thiol.

PubMed

Kalra, Sukirti; Jena, Gopabandhu; Tikoo, Kulbhushan; Mukhopadhyay, Anup Kumar

2007-05-18

The anticancer drug, 6-mercaptopurine (6MP) is subjected to metabolic clearance through xanthine oxidase (XOD) mediated hydroxylation, producing 6-thiouric acid (6TUA), which is excreted in urine. This reduces the effective amount of drug available for therapeutic efficacy. Co-administration of allopurinol, a suicide inhibitor of XOD, which blocks the hydroxylation of 6MP inadvertently enhances the 6MP blood level, counters this reduction. However, allopurinol also blocks the hydroxylation of hypoxanthine, xanthine (released from dead cancer cells) leading to their accumulation in the body causing biochemical complications such as xanthine nephropathy. This necessitates the use of a preferential XOD inhibitor that selectively inhibits 6MP transformation, but leaves xanthine metabolism unaffected. Here, we have characterized two such unique inhibitors namely, 2-amino-6-hydroxy-8-mercaptopurine (AHMP) and 2-amino-6-purinethiol (APT) on the basis of IC50 values, residual activity in bi-substrate simulative reaction and the kinetic parameters like Km, Ki, kcat. The IC50 values of AHMP for xanthine and 6MP as substrate are 17.71 +/- 0.29 microM and 0.54 +/- 0.01 microM, respectively and the IC50 values of APT for xanthine and 6MP as substrates are 16.38 +/- 0.21 microM and 2.57 +/- 0.08 microM, respectively. The Ki values of XOD using AHMP as inhibitor with xanthine and 6MP as substrate are 5.78 +/- 0.48 microM and 0.96 +/- 0.01 microM, respectively. The Ki values of XOD using APT as inhibitor with xanthine and 6MP as substrate are 6.61 +/- 0.28 microM and 1.30 +/- 0.09 microM. The corresponding Km values of XOD using xanthine and 6MP as substrate are 2.65 +/- 0.02 microM and 6.01 +/- 0.03 microM, respectively. The results suggest that the efficiency of substrate binding to XOD and its subsequent catalytic hydroxylation is much superior for xanthine in comparison to 6MP. In addition, the efficiency of the inhibitor binding to XOD is much more superior when 6MP is the substrate instead of xanthine. We further undertook the toxicological evaluation of these inhibitors in a single dose acute toxicity study in mice and our preliminary experimental results suggested that the inhibitors were equally non-toxic in the tested doses. We conclude that administration of either APT or AHMP along with the major anti-leukemic drug 6MP might serve as a good combination cancer chemotherapy regimen.

The role of the embryo and ethylene in avocado fruit mesocarp discoloration

PubMed Central

Hershkovitz, Vera; Friedman, Haya; Goldschmidt, Eliezer E.; Pesis, Edna

2009-01-01

Chilling injury (CI) symptoms in avocado (Persea americana Mill.) fruit, expressed as mesocarp discoloration, were found to be associated with embryo growth and ethylene production during cold storage. In cvs Ettinger and Arad most mesocarp discoloration was located close to the base of the seed and was induced by ethylene treatment in seeded avocado fruit. However, ethylene did not increase mesocarp discoloration in seedless fruit stored at 5 °C. Application of ethylene to whole fruit induced embryo development inside the seed. It also induced seedling elongation when seeds were imbibed separately. Persea americana ethylene receptor (PaETR) gene expression and polyphenol oxidase activity were highest close to the base of the seed and decreased gradually toward the blossom end. By contrast, expressions of PaETR transcript and polyphenol oxidase activity in seedless avocado fruit were similar throughout the pulp at the base of the fruit. Application of the ethylene inhibitor, 1-methylcyclopropene, decreased mesocarp browning, embryo development, seedling growth, and ion leakage, and down-regulated polyphenol oxidase activity. The results demonstrate that ethylene-mediated embryo growth in whole fruit is involved in the mesocarp response to ethylene perception and the development of CI disorders. PMID:19196750

Elevated concentrations of nonesterified fatty acids increase monocyte expression of CD11b and adhesion to endothelial cells.

PubMed

Zhang, Wei-Yang; Schwartz, Eric; Wang, Yingjie; Attrep, Jeanne; Li, Zhi; Reaven, Peter

2006-03-01

Monocyte proinflammatory activity has been demonstrated in obesity, insulin resistance, and type 2 diabetes, metabolic conditions that are frequently associated with elevated levels of nonesterified fatty acids (NEFA). We therefore tested the hypothesis that NEFA may induce monocyte inflammation. Monocytes exposed to NEFA for 2 days demonstrated a dose-related increase in intracellular reactive oxygen species (ROS) formation and adhesion to endothelial cells. All of these effects were inhibited by the coaddition of antioxidants such as glutathione or butylated hydroxytoluene, by inhibition of ROS generation by NADPH oxidase inhibitors, and by inhibition of protein kinase C, a recognized stimulator of NAPDH oxidase. Monocytes exposed to NEFA also demonstrated a significant increase in CD11b message expression. Stimulation of monocyte adhesion to endothelial cells by NEFA was inhibited by addition of neutralizing antibodies to either CD11b or CD18. Finally, surface expression of CD11b increased significantly on monocytes as measured by flow cytometry, after their incubation with NEFA. These studies indicate that elevated concentrations of NEFA may enhance integrin facilitated monocyte adhesion to endothelial cells and these effects appear mediated, in part, through activation of NADPH oxidase and oxidative stress.

The role of the embryo and ethylene in avocado fruit mesocarp discoloration.

PubMed

Hershkovitz, Vera; Friedman, Haya; Goldschmidt, Eliezer E; Pesis, Edna

2009-01-01

Chilling injury (CI) symptoms in avocado (Persea americana Mill.) fruit, expressed as mesocarp discoloration, were found to be associated with embryo growth and ethylene production during cold storage. In cvs Ettinger and Arad most mesocarp discoloration was located close to the base of the seed and was induced by ethylene treatment in seeded avocado fruit. However, ethylene did not increase mesocarp discoloration in seedless fruit stored at 5 degrees C. Application of ethylene to whole fruit induced embryo development inside the seed. It also induced seedling elongation when seeds were imbibed separately. Persea americana ethylene receptor (PaETR) gene expression and polyphenol oxidase activity were highest close to the base of the seed and decreased gradually toward the blossom end. By contrast, expressions of PaETR transcript and polyphenol oxidase activity in seedless avocado fruit were similar throughout the pulp at the base of the fruit. Application of the ethylene inhibitor, 1-methylcyclopropene, decreased mesocarp browning, embryo development, seedling growth, and ion leakage, and down-regulated polyphenol oxidase activity. The results demonstrate that ethylene-mediated embryo growth in whole fruit is involved in the mesocarp response to ethylene perception and the development of CI disorders.

Activation of multiple pH-regulatory pathways in granulocytes by a phosphotyrosine phosphatase antagonist.

PubMed Central

Bianchini, L; Nanda, A; Wasan, S; Grinstein, S

1994-01-01

Activated phagocytes undergo a massive burst of metabolic acid generation, yet must be able to maintain their cytosolic pH (pHi) within physiological limits. Peroxides of vanadate (V(4+)-OOH), potent inhibitors of phosphotyrosine phosphatases, have recently been shown to produce activation of the respiratory burst in HL60 granulocytes. We therefore investigated the effects of V(4+)-OOH on pHi homoeostasis in HL60 granulocytes, using a pH-sensitive fluorescent dye. V(4+)-OOH stimulation induced a biphasic pH change: a transient cytosolic acidification followed by a significant alkalinization. The initial acidification was prevented by inhibition of the NADPH oxidase and was absent in undifferentiated cells lacking oxidase activity. Analysis of the alkalinization phase demonstrated the involvement of the Na+/H+ antiporter, and also provided evidence for activation of two alternative H(+)-extrusion pathways: a bafilomycin-sensitive component, likely reflecting vacuolar-type H(+)-ATPase activity, and a Zn(2+)-sensitive H(+)-conductive pathway. Our results indicate that V(4+)-OOH stimulation not only activated the NADPH oxidase but concomitantly stimulated H(+)-extrusion pathways, enabling the cells to compensate for the massive production of intracellular H+ associated with the respiratory burst. PMID:8043000

Cinnamic Acid Increases Lignin Production and Inhibits Soybean Root Growth

PubMed Central

Salvador, Victor Hugo; Lima, Rogério Barbosa; dos Santos, Wanderley Dantas; Soares, Anderson Ricardo; Böhm, Paulo Alfredo Feitoza; Marchiosi, Rogério; Ferrarese, Maria de Lourdes Lucio; Ferrarese-Filho, Osvaldo

2013-01-01

Cinnamic acid is a known allelochemical that affects seed germination and plant root growth and therefore influences several metabolic processes. In the present work, we evaluated its effects on growth, indole-3-acetic acid (IAA) oxidase and cinnamate 4-hydroxylase (C4H) activities and lignin monomer composition in soybean (Glycine max) roots. The results revealed that exogenously applied cinnamic acid inhibited root growth and increased IAA oxidase and C4H activities. The allelochemical increased the total lignin content, thus altering the sum and ratios of the p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) lignin monomers. When applied alone or with cinnamic acid, piperonylic acid (PIP, a quasi-irreversible inhibitor of C4H) reduced C4H activity, lignin and the H, G, S monomer content compared to the cinnamic acid treatment. Taken together, these results indicate that exogenously applied cinnamic acid can be channeled into the phenylpropanoid pathway via the C4H reaction, resulting in an increase in H lignin. In conjunction with enhanced IAA oxidase activity, these metabolic responses lead to the stiffening of the cell wall and are followed by a reduction in soybean root growth. PMID:23922685

Cinnamic acid increases lignin production and inhibits soybean root growth.

PubMed

Salvador, Victor Hugo; Lima, Rogério Barbosa; dos Santos, Wanderley Dantas; Soares, Anderson Ricardo; Böhm, Paulo Alfredo Feitoza; Marchiosi, Rogério; Ferrarese, Maria de Lourdes Lucio; Ferrarese-Filho, Osvaldo

2013-01-01

Cinnamic acid is a known allelochemical that affects seed germination and plant root growth and therefore influences several metabolic processes. In the present work, we evaluated its effects on growth, indole-3-acetic acid (IAA) oxidase and cinnamate 4-hydroxylase (C4H) activities and lignin monomer composition in soybean (Glycine max) roots. The results revealed that exogenously applied cinnamic acid inhibited root growth and increased IAA oxidase and C4H activities. The allelochemical increased the total lignin content, thus altering the sum and ratios of the p-hydroxyphenyl (H), guaiacyl (G), and syringyl (S) lignin monomers. When applied alone or with cinnamic acid, piperonylic acid (PIP, a quasi-irreversible inhibitor of C4H) reduced C4H activity, lignin and the H, G, S monomer content compared to the cinnamic acid treatment. Taken together, these results indicate that exogenously applied cinnamic acid can be channeled into the phenylpropanoid pathway via the C4H reaction, resulting in an increase in H lignin. In conjunction with enhanced IAA oxidase activity, these metabolic responses lead to the stiffening of the cell wall and are followed by a reduction in soybean root growth.

Atpenins, potent and specific inhibitors of mitochondrial complex II (succinate-ubiquinone oxidoreductase)

PubMed Central

Miyadera, Hiroko; Shiomi, Kazuro; Ui, Hideaki; Yamaguchi, Yuichi; Masuma, Rokuro; Tomoda, Hiroshi; Miyoshi, Hideto; Osanai, Arihiro; Kita, Kiyoshi; Ōmura, Satoshi

2003-01-01

Enzymes in the mitochondrial respiratory chain are involved in various physiological events in addition to their essential role in the production of ATP by oxidative phosphorylation. The use of specific and potent inhibitors of complex I (NADH-ubiquinone reductase) and complex III (ubiquinol-cytochrome c reductase), such as rotenone and antimycin, respectively, has allowed determination of the role of these enzymes in physiological processes. However, unlike complexes I, III, and IV (cytochrome c oxidase), there are few potent and specific inhibitors of complex II (succinate-ubiquinone reductase) that have been described. In this article, we report that atpenins potently and specifically inhibit the succinate-ubiquinone reductase activity of mitochondrial complex II. Therefore, atpenins may be useful tools for clarifying the biochemical and structural properties of complex II, as well as for determining its physiological roles in mammalian tissues. PMID:12515859