In Vitro Effects of Concomitant Use of Herbal Preparations on Cytochrome P450s Involved in Clozapine Metabolism.
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SUBMITTER: Wang W
PROVIDER: S-EPMC6273925 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:Montelukast has been recommended as a selective in vitro and in vivo probe of cytochrome P450 (P450) CYP2C8 activity, but its selectivity toward this enzyme remains unclear. We performed detailed characterization of montelukast metabolism in vitro using human liver microsomes (HLMs), expressed P450s, and uridine 5'-diphospho-glucuronosyltransferases (UGTs). Kinetic and inhibition experiments performed at therapeutically relevant concentrations reveal that CYP2C8 and CYP2C9 are the principal enzymes responsible for montelukast 36-hydroxylation to 1,2-diol. CYP3A4 was the main catalyst of montelukast sulfoxidation and stereoselective 21-hydroxylation, and multiple P450s participated in montelukast 25-hydroxylation. We confirmed direct glucuronidation of montelukast to an acyl-glucuronide. We also identified a novel peak that appears consistent with an ether-glucuronide. Kinetic analysis in HLMs and experiments in expressed UGTs indicate that both metabolites were exclusively formed by UGT1A3. Comparison of in vitro intrinsic clearance in HLMs suggest that direct glucuronidation may play a greater role in the overall metabolism of montelukast than does P450-mediated oxidation, but the in vivo contribution of UGT1A3 needs further testing. In conclusion, our in vitro findings provide new insight toward montelukast metabolism. The utility of montelukast as a probe of CYP2C8 activity may be compromised owing to involvement of multiple P450s and UGT1A3 in its metabolism.
| S-EPMC4658491 | biostudies-literature
Project description:Cytochrome P450 monooxygenases (CYPs/P450s) are heme thiolate proteins present in species across the biological kingdoms. By virtue of their broad substrate promiscuity and regio- and stereo-selectivity, these enzymes enhance or attribute diversity to secondary metabolites. Actinomycetes species are well-known producers of secondary metabolites, especially Salinispora species. Despite the importance of P450s, a comprehensive comparative analysis of P450s and their role in secondary metabolism in Salinispora species is not reported. We therefore analyzed P450s in 126 strains from three different species Salinispora arenicola, S. pacifica, and S. tropica. The study revealed the presence of 2643 P450s that can be grouped into 45 families and 103 subfamilies. CYP107 and CYP125 families are conserved, and CYP105 and CYP107 families are bloomed (a P450 family with many members) across Salinispora species. Analysis of P450s that are part of secondary metabolite biosynthetic gene clusters (smBGCs) revealed Salinispora species have an unprecedented number of P450s (1236 P450s-47%) part of smBGCs compared to other bacterial species belonging to the genera Streptomyces (23%) and Mycobacterium (11%), phyla Cyanobacteria (8%) and Firmicutes (18%) and the classes Alphaproteobacteria (2%) and Gammaproteobacteria (18%). A peculiar characteristic of up to six P450s in smBGCs was observed in Salinispora species. Future characterization Salinispora species P450s and their smBGCs have the potential for discovering novel secondary metabolites.
| S-EPMC9143469 | biostudies-literature
Project description:The metabolism of flavone-8-acetic acid (FAA) has been hypothesized to be partly responsible for its potent anticancer activity in mice. The purpose of this study was to identify the mouse enzymes involved in FAA Phase I metabolism and evaluate their possible induction in vivo by FAA. Mouse microsomes metabolized FAA into 6 metabolites: 3',4'-dihydrodiol-FAA, 5,6-epoxy-FAA, 4'-OH-FAA, 3'-OH-FAA, 3',4'-epoxy-FAA and 6-OH-FAA. Using Cyp-specific inhibitors (furafylline, Cyp1a2; α-naphthoflavone, Cyp1b1; tranylcypromine, Cyp2b9; quercetin, Cyp2c29; quinidine, 2d9; diethyldithiocarbamate, Cyp2e1; ketoconazole, Cyp3a11), the formation of 5,6-epoxy-FAA was mainly attributed to Cyps 1a2, 1b1, 2b9, 2c29 and 2e1, whereas the 3',4'-epoxy-FAA was formed by Cyps 2b9 and 3a11. The 4'-OH-FAA was generated by Cyps 1a2, 1b1, 2b9 and 2e1, and the 6-OH-FAA was formed by Cyps 1b1 and 2c9. Using the epoxide scavenger N-acetyl cysteine, 4'-OH-FAA, 3'-OH-FAA and 6-OH-FAA were shown to derive partly from non enzymatic isomerisation of their corresponding epoxides. The specific epoxide hydrolase inhibitor elaidamide allowed the confirmation that 3',4'-dihydrodiol-FAA was formed via the epoxide hydrolase. FAA treatment in vivo in mice led to a significant increase in the hepatic expression of Cyp1a2 (1.9-fold), 2e1 (2.1-fold), 2b10 (3.2-fold), 2d9 (2.3-fold) and 3a11 (2.2-fold), as evaluated by qRT-PCR. In conclusion, several Cyps were shown to be involved in FAA metabolism, particularly Cyps 3a11 and 2b9 which were responsible for the formation of the principal metabolites (5,6-epoxy-FAA, 3',4'-epoxy-FAA), and that FAA could induce the expression of several Cyps after in vivo administration. The possible implication of these enzymes in the in vivo anticancer activity of FAA in mice is discussed.
| S-EPMC3743746 | biostudies-literature
Project description:We investigated the metabolic capabilities of C. elegans using compounds whose metabolism has been well characterised in mammalian systems. We find that similar metabolites are produced in C. elegans as in mammals but that C. elegans is deficient in CYP1-like metabolism, as has been seen in other studies. We show that CYP-34A9, CYP-34A10 and CYP-36A1 are the principal enzymes responsible for the metabolism of tolbutamide in C. elegans. These are related to the mammalian enzymes that metabolise this compound but are not the closest homologs suggesting that sequence comparison alone will not predict functional conservation among cytochrome P450s. In mammals, metabolite production from amytryptiline and dextromethorphan is dependent on specific cytochrome P450s. However, in C. elegans we did not find evidence of similar specificity: the same metabolites were produced but in small amounts by numerous cytochrome P450s. We conclude that, while some aspects of cytochrome P450 mediated metabolism in C. elegans are similar to mammals, there are differences in the production of some metabolites and in the underlying genetics of metabolism.
| S-EPMC6127299 | biostudies-literature
Project description:BackgroundUterine fibroids are the most common non-malignant growths in women of childbearing age. They are associated with heavy menstrual bleeding and subfertility. Herbal preparations are commonly used as alternatives to surgical procedures.ObjectivesTo assess the benefits and risks of herbal preparations for uterine fibroids.Search strategyAuthors searched following electronic databases: the Trials Registers of the Cochrane Menstrual Disorders and Subfertility Group and the Cochrane Complementary Medicine Field, the Cochrane Central Register of Controlled Trials (CENTRAL) (The Cochrane Library 2008, Issue 3), MEDLINE, EMBASE, the Chinese Biomedical Database, the Traditional Chinese Medical Literature Analysis and Retrieval System (TCMLARS), AMED, and LILACS. The searches ended on 31st December 2008.Selection criteriaRandomised controlled trials comparing herbal preparations with no intervention, placebo, medical treatment or surgical procedures in women with uterine fibroids. We also included trials of herbal preparations with or without conventional therapy.Data collection and analysisTwo review authors collected data independently. We assessed trial risk of bias according to our methodological criteria . We presented dichotomous data as risk ratios (RR) and continuous outcomes as mean difference (MD), both with 95% confidence intervals (CI).Main resultsWe included two randomised trials (involved 150 women) with clear description of randomisation methods. The methodological risk of bias of the trials varied. There were variations in the tested herbal preparations, and the treatment duration was six months. The outcomes available were not the primary outcomes selected for this review, such as symptom relief or the need for surgical treatment; trials mainly reported outcomes in terms of shrinkage of the fibroids.Compared with mifepristone, Huoxue Sanjie decoction showed no significant difference in the disappearance of uterine fibroids, number of patients with shrinking of uterine fibroids or average volume of uterine fibroids, but less effective than mifepristone on reducing average size of uterus (mean difference 23.23 cm(3),95% confidence interval 17.85 to 28.61). There was no significant difference between Nona Roguy herbal product and GnRH agonist in average volume of uterine fibroids or size of uterus. No serious adverse effects from herbal preparations was reported.Authors' conclusionsCurrent evidence does not support or refute the use of herbal preparations for treatment of uterine fibroids due to insufficient studies of large sample and high quality. Further high quality trials evaluating clinically relevant outcomes are warranted.
| S-EPMC3155698 | biostudies-literature
Project description:Cytochrome P450 monooxygenases (CYPs/P450s) are among the most catalytically-diverse enzymes, capable of performing enzymatic reactions with chemo-, regio-, and stereo-selectivity. Our understanding of P450s' role in secondary metabolite biosynthesis is becoming broader. Among bacteria, Bacillus species are known to produce secondary metabolites, and recent studies have revealed the presence of secondary metabolite biosynthetic gene clusters (BGCs) in these species. However, a comprehensive comparative analysis of P450s and P450s involved in the synthesis of secondary metabolites in Bacillus species has not been reported. This study intends to address these two research gaps. In silico analysis of P450s in 128 Bacillus species revealed the presence of 507 P450s that can be grouped into 13 P450 families and 28 subfamilies. No P450 family was found to be conserved in Bacillus species. Bacillus species were found to have lower numbers of P450s, P450 families and subfamilies, and a lower P450 diversity percentage compared to mycobacterial species. This study revealed that a large number of P450s (112 P450s) are part of different secondary metabolite BGCs, and also identified an association between a specific P450 family and secondary metabolite BGCs in Bacillus species. This study opened new vistas for further characterization of secondary metabolite BGCs, especially P450s in Bacillus species.
| S-EPMC6275058 | biostudies-literature
Project description:Using oxygen and NADPH, the redox enzymes cytochrome P450 (CYP) and its reductase (CPR) work in tandem to carry out the phase I metabolism of a vast majority of drugs and xenobiotics. As per the erstwhile understanding of the catalytic cycle, binding of the substrate to CYP's heme distal pocket allows CPR to pump electrons through a CPR-CYP complex. In turn, this trigger (a thermodynamic push of electrons) leads to the activation of oxygen at CYP's heme-center, to give Compound I, a two-electron deficient enzyme reactive intermediate. The formation of diffusible radicals and reactive oxygen species (DROS, hitherto considered an undesired facet of the system) was attributed to the heme-center. Recently, we had challenged these perceptions and proposed the murburn ("mured burning" or "mild unrestricted burning") concept to explain heme enzymes' catalytic mechanism, electron-transfer phenomena and the regulation of redox equivalents' consumption. Murburn concept incorporates a one-electron paradigm, advocating obligatory roles for DROS. The new understanding does not call for high-affinity substrate-binding at the heme distal pocket of the CYP (the first and the most crucial step of the erstwhile paradigm) or CYP-CPR protein-protein complexations (the operational backbone of the erstwhile cycle). Herein, the dynamics of reduced nicotinamide nucleotides' consumption, peroxide formation and depletion, product(s) formation, etc. was investigated with various controls, by altering reaction variables, environments and through the incorporation of diverse molecular probes. In several CYP systems, control reactions lacking the specific substrate showed comparable or higher peroxide in milieu, thereby discrediting the foundations of the erstwhile hypothesis. The profiles obtained by altering CYP:CPR ratios and the profound inhibitions observed upon the incorporation of catalytic amounts of horseradish peroxidase confirm the obligatory roles of DROS in milieu, ratifying murburn as the operative concept. The mechanism of uncoupling (peroxide/water formation) was found to be dependent on multiple one and two electron equilibriums amongst the reaction components. The investigation explains the evolutionary implications of xenobiotic metabolism, confirms the obligatory role of diffusible reactive species in routine redox metabolism within liver microsomes and establishes that a redox enzyme like CYP enhances reaction rates (achieves catalysis) via a novel (hitherto unknown) modality.
| S-EPMC4918403 | biostudies-literature
Project description:Sakuranetin (SKN), found in cherry trees and rice, is a flavanone with various pharmacological activities. It is biosynthesized from naringenin in rice or cherry trees, and the metabolism of SKN has been studied in non-human species. The present study aimed to investigate the metabolic pathways of SKN in human liver microsomes and identify the phase I and phase II metabolites, as well as evaluate the potential for drug⁻herb interactions through the modulation of drug metabolizing enzymes (DMEs). HPLC-DAD and HPLC-electrospray mass spectrometry were used to study the metabolic stability and identify the metabolites from human liver microsomes incubated with SKN. The potential of SKN to inhibit the DMEs was evaluated by monitoring the formation of a DME-specific product. The cytochrome P450 2B6 and 3A4-inductive effects were studied using promoter reporter assays in human hepatocarcinoma cells. The major pathways for SKN metabolism include B-ring hydroxylation, 5-O-demethylation, and conjugation with glutathione or glucuronic acid. The phase I metabolites were identified as naringenin and eriodictyol. SKN was found to be a UDP-glucuronosyltransferases (UGT) 1A9 inhibitor, whereas it induced transactivation of the human pregnane X receptor-mediated cytochrome P450 (CYP) 3A4 gene.
| S-EPMC6100415 | biostudies-literature
Project description:Plant alkaloids constitute an important class of bioactive chemicals with applications in medicine and agriculture. However, the knowledge gap of the diversity and biosynthesis of phytoalkaloids prevents systematic advances in biotechnology for engineered production of these high-value compounds. In particular, the identification of cytochrome P450s driving the structural diversity of phytoalkaloids has remained challenging. Here, we use a combination of reverse genetics with discovery metabolomics and multivariate statistical analysis followed by in planta transient assays to investigate alkaloid diversity and functionally characterize two candidate cytochrome P450s genes from Atropa belladonna without a priori knowledge of their functions or information regarding the identities of key pathway intermediates. This approach uncovered a largely unexplored root localized alkaloid sub-network that relies on pseudotropine as precursor. The two cytochrome P450s catalyze N-demethylation and ring-hydroxylation reactions within the early steps in the biosynthesis of diverse N-demethylated modified tropane alkaloids.
| S-EPMC9250511 | biostudies-literature
Project description:A field-collected Aphis gossypii clone [Kushima resistant (KR) clone] was resistant to neonicotinoid insecticides (23.8- to 394-fold). RNA-seq and next-generation sequence analyses were conducted to identify nine cytochrome P450 (CYP) genes that were significantly upregulated in the KR clone as compared with those in the insecticide-susceptible clone. A. gossypii P450s were transiently and efficiently expressed in S2 cell to show that CYP6CY22 (c21228) and CYP6CY13 (c21368), which were the most upregulated of the nine P450s in the KR clone, did not degrade sulfoxaflor, a new class of insecticides acting on insect nAChRs, but markedly metabolized all of the neonicotinoids tested. Hence, P450s are likely to underpin neonicotinoid resistance in other aphids as well in the future, and the P450 expression protocol established here will prompt studies on P450-medidated insecticide resistance and structural analyses of relevant metabolites.
| S-EPMC6173126 | biostudies-literature