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https://www.readbyqxmd.com/read/29018344/xanthates-as-useful-probes-for-testing-the-active-sites-of-cytochromes-p450-4a11-and-2e1
#1
Tsveta Stoyanova, Iglika Lessigiarska, Momir Mikov, Ilza Pajeva, Stanislav Yanev
Xanthates (alkyl or aryl derivatives of dithiocarbonic acid) have been shown to be selective mechanism-based inactivators of cytochromes P450 2B1/2B6 and 2E1 due to covalent binding of a reactive intermediate to apoprotein after double hydrogen abstraction at α-carbon atom, suggesting interaction of the xanthate dithiocarbonic head with the enzyme heme. The structures of xanthates with a long alkyl chain are similar to the fatty acids. Saturated fatty acids (FA) such as lauric acid (LA), are metabolized by different cytochrome P450 isoforms to ω- and (ω-1)-hydroxy products, in humans done by CYP4A11 and CYP2E1, respectively...
2017: Frontiers in Pharmacology
https://www.readbyqxmd.com/read/28994497/effects-of-vernonia-cinerea-compounds-on-drug-metabolizing-cytochrome-p450s-in-human-liver-microsomes
#2
Phisit Pouyfung, Songklod Sarapusit, Pornpimol Rongnoparut
Vernonia cinerea has been widely used in traditional medicines for various diseases and shown to aid in smoking abstinence and has anticancer properties. V. cinerea bioactive compounds, including flavonoids and hirsutinolide-type sesquiterpene lactones, have shown an inhibition effect on the nicotine-metabolizing cytochrome P450 2A6 (CYP2A6) enzyme and hirsutinolides reported suppressing cancer growth. In this study, V. cinerea ethanol extract and its bioactive compounds, including four flavonoids and four hirsutinolides, were investigated for an inhibitory effect on human liver microsomal CYPs 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, 2E1, and 3A4 using cocktail inhibition assays combined with LC-MS/MS analysis...
October 10, 2017: Phytotherapy Research: PTR
https://www.readbyqxmd.com/read/28962520/editor-s-highlight-complete-attenuation-of-mouse-lung-cell-proliferation-and-tumorigenicity-in-cyp2f2-knockout-and-cyp2f1-humanized-mice-exposed-to-inhaled-styrene-for-up-to-2%C3%A2-years-supports-a-lack-of-human-relevance
#3
George Cruzan, James S Bus, Marcy I Banton, Satinder S Sarang, Robbie Waites, Debra B Layko, James Raymond, Darol Dodd, Melvin E Andersen
Styrene is a mouse-specific lung carcinogen, and short-term mode of action studies have demonstrated that cytotoxicity and/or cell proliferation, and genomic changes are dependent on CYP2F2 metabolism. The current study examined histopathology, cell proliferation, and genomic changes in CD-1, C57BL/6 (WT), CYP2F2(-/-) (KO), and CYP2F2(-/-) (CYP2F1, 2B6, 2A13-transgene) (TG; humanized) mice following exposure for up to 104 weeks to 0- or 120-ppm styrene vapor. Five mice per treatment group were sacrificed at 1, 26, 52, and 78 weeks...
October 1, 2017: Toxicological Sciences: An Official Journal of the Society of Toxicology
https://www.readbyqxmd.com/read/28951217/assessing-molecular-initiating-events-mies-key-events-kes-and-modulating-factors-mfs-for-styrene-responses-in-mouse-lungs-using-whole-genome-gene-expression-profiling-following-1-day-and-multi-week-exposures
#4
Melvin E Andersen, George Cruzan, Michael B Black, Salil N Pendse, Darol Dodd, James S Bus, Satinder S Sarang, Marcy I Banton, Robbie Waites, Patrick D McMullen
Styrene increased lung tumors in mice at chronic inhalation exposures of 20ppm and greater. MIEs, KEs and MFs were examined using gene expression in three strains of male mice (the parental C57BL/6 strain, a CYP2F2(-/-) knock out and a CYP2F2(-/-) transgenic containing human CYP2F1, 2A13 and 2B6). Exposures were for 1-day and 1, 4 and 26weeks. After 1-day exposures at 1, 5, 10, 20, 40 and 120ppm significant increases in differentially expressed genes (DEGs) occurred only in parental strain lungs where there was already an increase in DEGs at 5ppm and then many thousands of DEGs by 120ppm...
September 23, 2017: Toxicology and Applied Pharmacology
https://www.readbyqxmd.com/read/28934153/inhibitory-effect-of-selaginellins-from-selaginella-tamariscina-beauv-spring-against-cytochrome-p450-and-uridine-5-diphosphoglucuronosyltransferase-isoforms-on-human-liver-microsomes
#5
Jae-Kyung Heo, Phi-Hung Nguyen, Won Cheol Kim, Nguyen Minh Phuc, Kwang-Hyeon Liu
Selaginella tamariscina (Beauv.) has been used for traditional herbal medicine for treatment of cancer, hepatitis, and diabetes in the Orient. Numerous bioactive compounds including alkaloids, flavonoids, lignans, and selaginellins have been identified in this medicinal plant. Among them, selaginellins having a quinone methide unit and an alkylphenol moiety have been known to possess anticancer, antidiabetic, and neuroprotective activity. Although there have been studies on the biological activities of selaginellins, their modulatory potential of cytochrome P450 (P450) and uridine 5'-diphosphoglucuronosyltransferase (UGT) activities have not been previously evaluated...
September 21, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28858450/ketamine-for-depression-5-potential-pharmacokinetic-and-pharmacodynamic-drug-interactions
#6
REVIEW
Chittaranjan Andrade
Ketamine, administered in subanesthetic doses, is gaining recognition as an off-label treatment for severe and even treatment-refractory depression. This article explores potential pharmacokinetic and pharmacodynamic drug interactions of relevance to the use of ketamine in depression. Sparse evidence suggests that ketamine will not induce clinically significant drug interactions except to the extent that these are predictable by its clinical actions. A small body of literature indicates that drugs that induce cytochrome P450 (CYP)2B6 and CYP3A4 will reduce exposure to ketamine and that drugs that inhibit these enzymes will increase exposure to ketamine...
July 2017: Journal of Clinical Psychiatry
https://www.readbyqxmd.com/read/28834279/the-cytochrome-p450-enzyme-responsible-for-the-production-of-z-norendoxifen-in-vitro
#7
Dabei Tang, Zhong Chu, Jessica Bo Li Lu, Jinzhong Liu, Qingyuan Zhang
BACKGROUND: Norendoxifen, an active metabolite of tamoxifen, is a potent aromatase inhibitor. Little information is available regarding production of norendoxifen in vitro. Here, we conducted a series of kinetic and inhibition studies in human liver microsomes (HLMs) and expressed P450s to study the metabolic disposition of norendoxifen. METHODS: To validate that norendoxifen was the metabolite of endoxifen, metabolites in HLMs incubates of endoxifen were measured using a HPLC/MS/MS method...
August 17, 2017: Chemistry & Biodiversity
https://www.readbyqxmd.com/read/28791666/clinical-pharmacokinetics-and-pharmacodynamics-of-micafungin
#8
REVIEW
Roeland E Wasmann, Eline W Muilwijk, David M Burger, Paul E Verweij, Catherijne A Knibbe, Roger J Brüggemann
Micafungin is a selective inhibitor of the synthesis of fungal 1,3-β-D-glucan, an essential component of the fungal cell wall. It is available as a powder for infusion only and is registered for the treatment of invasive and esophageal candidiasis in addition to prophylaxis of Candida infections in both adults and children. Average exposure after a single intravenous 100 mg dose in healthy adults is 133 mg h/L. Both exposure and maximum plasma concentration show linear dose proportional pharmacokinetics (PK) over a 0...
August 8, 2017: Clinical Pharmacokinetics
https://www.readbyqxmd.com/read/28699698/reduced-dosing-and-liability-in-methadone-maintenance-treatment-by-targeting-oestrogen-signal-for-morphine-addiction
#9
Yao-Chang Chiang, Ruey-Yun Wang, Chieh-Liang Huang, Shue-Hwa Chen, Wen-Jing Ho, Hsien-Yuan Lane, Ing-Kang Ho, Hwei-Ting Yang, Wen-Lung Ma
Methadone maintenance treatment (MMT) is the major tapering therapy for morphine addictive patients. There have gender differences reported in response to MMT. This study discovered that the estrogen-response element single nucleotide polymorphism (ERE-SNP; rs16974799, C/T) of cytochrome 2B6 gene (cyp2b6; methadone catabolic enzyme) responded differently to MMT dosing. Oestradiol was associated with high MMT dosing, high enantiomer (R- or S-) of 2-ethylidene-1,5-dimethyl-3,3-dipheny-pyrrolidine (EDDP; methadone metabolite) to methadone ratio and increased drug-seeking behaviour, implicating oestradiol-CYP-EDDP/methadone axis decreasing MMT efficacy...
July 12, 2017: Journal of Cellular and Molecular Medicine
https://www.readbyqxmd.com/read/28692529/cyp2b6-genotypes-and-early-efavirenz-based-hiv-treatment-outcomes-in-botswana
#10
Robert Gross, Scarlett L Bellamy, Bakgaki Ratshaa, Xiaoyan Han, Marijana Vujkovic, Richard Aplenc, Andrew P Steenhoff, Mosepele Mosepele, Ganesh Moorthy, Athena F Zuppa, Brian L Strom, Gregory P Bisson
OBJECTIVES: To determine the association between cytochrome p450 2B6 genotypes and efavirenz-based HIV treatment outcomes. DESIGN: Observational cohort study of HIV-infected adults initiating efavirenz-based regimens in Botswana. METHODS: The primary endpoint was a composite of death or loss to care or HIV RNA more than 25 copies/ml at 6 months. CYP2B6 516G>T and 983T>C genotyping was done with Taqman Open Array platform. Adverse experiences were measured by using the Subject Experience Questionnaire...
September 24, 2017: AIDS
https://www.readbyqxmd.com/read/28674261/preliminary-evaluation-of-three-dimensional-primary-human-hepatocyte-culture-system-for-assay-of-drug-metabolizing-enzyme-inducing-potential
#11
Hiroshi Arakawa, Hiroki Kamioka, Tomoko Jomura, Satoshi Koyama, Yoko Idota, Kentaro Yano, Hajime Kojima, Takuo Ogihara
Drug-induced liver injury (DILI) is a common reason for withdrawal of candidate drugs from clinical trials, or of approved drugs from the market. DILI may be induced not only by intact parental drugs, but also by metabolites or intermediates, and therefore should be evaluated in the enzyme-induced state. Here, we present a protocol for assay of drug-metabolizing enzyme-inducing potential using three-dimensional (3D) primary cultures of human hepatocytes (hepatocyte spheroids). Hepatocyte spheroids could be used up to 21 d after seeding (pre-culture for 7 d and exposure to inducer for up to 14 d), based on preliminary evaluation of basal activities of CYP subtypes and mRNA expression of the corresponding transcription factor and xenobiotic receptors (aryl hydrocarbon receptor (AhR), constitutive androstane receptor (CAR) and pregnane X receptor (PXR))...
2017: Biological & Pharmaceutical Bulletin
https://www.readbyqxmd.com/read/28663285/inhibitory-effects-of-selected-antituberculosis-drugs-on-common-human-hepatic-cytochrome-p450-and-udp-glucuronosyltransferase-enzymes
#12
Lei Cao, David J Greenblatt, Awewura Kwara
The comorbidities of tuberculosis and diseases such as HIV require long-term treatment with multiple medications. Despite substantial in vitro and in vivo information on effects of rifampicin and isoniazid on human CYPs, there is limited published data regarding the inhibitory effects of other anti-TB drugs on human CYPs and UGTs. The inhibitory effects of five first-line anti-TB drugs (isoniazid, rifampicin, pyrazinamide, ethambutol, and rifabutin), and the newly approved bedaquiline, were evaluated for six common human hepatic UGT enzymes (UGT1A1, 1A4, 1A6, 1A9, 2B7 and 2B15) in vitro using HLMs...
September 2017: Drug Metabolism and Disposition: the Biological Fate of Chemicals
https://www.readbyqxmd.com/read/28653752/the-potential-of-epimedium-koreanum-nakai-for-herb-drug-interaction
#13
Qingxiang Zhong, Ziqi Shi, Li Zhang, Rongling Zhong, Zhi Xia, Jing Wang, Hao Wu, Yutong Jiang, E Sun, Yingjie Wei, Liang Feng, Zhenhai Zhang, Dan Liu, Jie Song, Xiaobin Jia
OBJECTIVES: This study aims to investigate potential herb-drug interactions (HDI) of Epimedium koreanum Nakai. METHODS: Human liver microsomes (HLMs) were used to determine the enzyme kinetics of the major human cytochrome P450s (CYPs). Inducible potential of E. koreanum on CYP1A2, 2B6, 2C19 and 3A4 activities of human primary hepatocytes was also examined. KEY FINDINGS: Ethanol extract of E. koreanum showed direct inhibitory potency for CYP1A2 (IC50  = 121...
June 27, 2017: Journal of Pharmacy and Pharmacology
https://www.readbyqxmd.com/read/28648140/oxidation-of-1-chloropyrene-by-human-cyp1-family-and-cyp2a-subfamily-cytochrome-p450-enzymes-catalytic-roles-of-two-cyp1b1-and-five-cyp2a13-allelic-variants
#14
Tsutomu Shimada, Norie Murayama, Kensaku Kakimoto, Shigeo Takenaka, Young-Ran Lim, Sora Yeom, Donghak Kim, Hiroshi Yamazaki, F Peter Guengerich, Masayuki Komori
1. 1-Chloropyrene, one of the major chlorinated polycyclic aromatic hydrocarbon contaminants, was incubated with human cytochrome P450 (P450 or CYP) enzymes including CYP1A1, 1A2, 1B1, 2A6, 2A13, 2B6, 2C9, 2D6, 2E1, 3A4 and 3A5. Catalytic differences in 1-chloropyrene oxidation by polymorphic two CYP1B1 and five CYP2A13 allelic variants were also examined. 2. CYP1A1 oxidized 1-chloropyrene at the 6- and 8-positions more actively than at the 3-position, while both CYP1B1.1 and 1B1.3 preferentially catalyzed 6-hydroxylation...
July 21, 2017: Xenobiotica; the Fate of Foreign Compounds in Biological Systems
https://www.readbyqxmd.com/read/28627229/cobicistat-versus-ritonavir-similar-pharmacokinetic-enhancers-but-some-important-differences
#15
Alice Tseng, Christine A Hughes, Janet Wu, Jason Seet, Elizabeth J Phillips
OBJECTIVE: To describe properties of cobicistat and ritonavir; compare boosting data with atazanavir, darunavir, and elvitegravir; and summarize antiretroviral and comedication interaction studies, with a focus on similarities and differences between ritonavir and cobicistat. Considerations when switching from one booster to another are discussed. DATA SOURCES: A literature search of MEDLINE was performed (1985 to April 2017) using the following search terms: cobicistat, ritonavir, pharmacokinetic, drug interactions, booster, pharmacokinetic enhancer, HIV, antiretrovirals...
November 2017: Annals of Pharmacotherapy
https://www.readbyqxmd.com/read/28608515/efavirenz-clearances-in-vitro-and-in-vivo-in-six-cynomolgus-monkeys-associated-with-polymorphic-cytochrome-p450-2c9-and-simulated-by-individual-physiologically-based-pharmacokinetic-models
#16
Masahiro Utoh, Tomonori Miura, Takashi Kusama, Shotaro Uehara, Makiko Shimizu, Yasuhiro Uno, Hiroshi Yamazaki
Cynomolgus monkey cytochrome P450 2C9 (formerly known as P450 2C43) variation was reportedly associated with metabolic clearance of the antiretroviral drug efavirenz in vivo (in three wild-type, one heterozygote and two homozygote animals), being unlikely in the case of human P450 2B6-dependent efavirenz clearance. In this study, the liver microsomal elimination rates of efavirenz for the same individual animals previously treated with intravenous/oral administrations of efavirenz showed significant reductions associated with the P450 2C9 p...
June 13, 2017: Biopharmaceutics & Drug Disposition
https://www.readbyqxmd.com/read/28603633/in-vitro-metabolism-of-exemestane-by-hepatic-cytochrome-p450s-impact-of-nonsynonymous-polymorphisms-on-formation-of-the-active-metabolite-17%C3%AE-dihydroexemestane
#17
Amity Peterson, Zuping Xia, Gang Chen, Philip Lazarus
Exemestane (EXE) is an endocrine therapy commonly used by postmenopausal women with hormone-responsive breast cancer due to its potency in inhibiting aromatase-catalyzed estrogen synthesis. Preliminary in vitro studies sought to identify phase I EXE metabolites and hepatic cytochrome P450s (CYP450s) that participate in EXE biotransformation. Phase I metabolites were identified by incubating EXE with HEK293-overexpressed CYP450s. CYP450s 1A2, 2C8, 2C9, 2C19, 2D6, 3A4, and 3A5 produce 17β-dihydroexemestane (17β-DHE), an active major metabolite, as well as two inactive metabolites...
June 2017: Pharmacology Research & Perspectives
https://www.readbyqxmd.com/read/28527150/development-of-in-silico-protocols-to-predict-structural-insights-into-the-metabolic-activation-pathways-of-xenobiotics
#18
M Kalim A Khan, Salman Akhtar, Jamal M Arif
To establish in silico model to predict the structural insight into the metabolic bioactivation pathway of xenobiotics, we considered two specific and one non-specific mammary procarcinogen [e.g., dibenzo[a,l]pyrene (DBP), 7,12-dimethylbenz[a]anthracene (DMBA), and benzo[a]pyrene (BP)]. The CYP1A1, 1B1, 2C9, 1A2 and 2B6 reported in wet-lab studies to actively metabolize DBP also showed strong binding energies (kcal/mol) of -11.50, -10.67, -10.37, -9.76 and -9.72, respectively, with inhibition constants ranging between 0...
May 19, 2017: Interdisciplinary Sciences, Computational Life Sciences
https://www.readbyqxmd.com/read/28496040/induction-of-human-cytochrome-p450-3a-enzymes-in-cultured-placental-cells-by-thalidomide-and-relevance-to-bioactivation-and-toxicity
#19
Norie Murayama, Yasuhiro Kazuki, Daisuke Satoh, Kazuya Arata, Tasuku Harada, Norio Shibata, F Peter Guengerich, Hiroshi Yamazaki
Evidence has been presented for auto-induced human cytochrome P450 3A enzyme involvement in the teratogenicity and clinical outcome of thalidomide due to oxidation to 5-hydroxythalidomide and subsequent metabolic activation in livers. In this study, more relevant human placenta preparations and placental BeWo cells showed low but detectable P450 3A4/5 mRNA expression and drug oxidation activities. Human placental microsomal fractions from three subjects showed detectable midazolam 1´- and 4-hydroxylation and thalidomide 5-hydroxylation activities...
2017: Journal of Toxicological Sciences
https://www.readbyqxmd.com/read/28484907/inhibition-of-cytochrome-p450-and-uridine-5-diphospho-glucuronosyltransferases-by-mam-2201-in-human-liver-microsomes
#20
Tae Yeon Kong, Ju-Hyun Kim, Soon-Sang Kwon, Jae Chul Cheong, Hee Seung Kim, Moon Kyo In, Hye Suk Lee
MAM-2201, a synthetic cannabinoid, is a potent agonist of the cannabinoid receptors and is increasingly used as an illicit recreational drug. The inhibitory effects of MAM-2201 on major drug-metabolizing enzymes such as cytochrome P450s (CYPs) and uridine 5'-diphospho-glucuronosyltransferases (UGTs) have not yet been investigated although it is widely abused, sometimes in combination with other drugs. We evaluated the inhibitory effects of MAM-2201 on eight major human CYPs (CYPs 1A2, 2A6, 2B6, 2C8, 2C9, 2C19, 2D6, and 3A4) and six UGTs (UGTs 1A1, 1A3, 1A4, 1A6, 1A9, and 2B7) of pooled human liver microsomes; we thus explored potential MAM-2201-induced drug interactions...
May 8, 2017: Archives of Pharmacal Research
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