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Yamazoe Y, Yoshinari K. Construction of a fused grid-based CYP2C18-Template system and its application to drug metabolism. Drug Metab Pharmacokinet 2024; 54:100534. [PMID: 38070310 DOI: 10.1016/j.dmpk.2023.100534] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/11/2023] [Revised: 10/08/2023] [Accepted: 10/16/2023] [Indexed: 02/06/2024]
Abstract
Detailed estimation of cytochrome P450 (CYP)-mediated metabolisms of medicine and other chemicals is necessary for the efficacy and safety assessments. Data on the metabolisms mediated by minor CYP enzymes like CYP2C18 are often not available in metabolisms and safety assessments of chemicals except for medical drugs developed recently. A ligand-accessible space in the active site of human CYP2C18 was thus reconstituted as a fused grid-based Template with the use of structural data of its ligands. An evaluation system of CYP2C18-mediated metabolism was then developed on Template with the introduction of the idea of movement and fastening of ligands after Trigger-residue contact. Reciprocal comparison of the data of simulations on Template with experimental results suggested a unified way of the interaction of CYP2C18, in similar to the CYP2C8 interaction (Drug Metab Pharmacokinet 2023, in press). These experiments also displayed the roles of initial Trigger-residue-localizations on their distinct catalyses among human CYP2C enzymes. Simulation experiments for over 130 reactions of CYP2C18 ligands supported the system established.
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Affiliation(s)
- Yasushi Yamazoe
- Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, 980-8578, Japan; Division of Risk Assessment, National Institute of Health Sciences, Tonomachi 3-25-26, Kawasaki-ku, Kawasaki, 210-9501, Japan.
| | - Kouichi Yoshinari
- Laboratory of Molecular Toxicology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
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2
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Yamamura Y, Yoshinari K, Yamazoe Y. Construction of a fused grid-based CYP2C19-Template system and the application. Drug Metab Pharmacokinet 2023; 48:100481. [PMID: 36813636 DOI: 10.1016/j.dmpk.2022.100481] [Citation(s) in RCA: 3] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/10/2022] [Revised: 10/05/2022] [Accepted: 10/22/2022] [Indexed: 11/11/2022]
Abstract
A ligand-accessible space in the CYP2C19 active site was reconstituted as a fused grid-based Template with the use of structural data of the ligands. An evaluation system of CYP2C19-mediated metabolism has been developed on Template with the introduction of the idea of Trigger-residue initiated ligand-movement and fastening. Reciprocal comparison of the data of simulation on Template with experimental results suggested a unified way of the interaction of CYP2C19 and its ligands through the simultaneous plural-contact with Rear-wall of Template. CYP2C19 was expected to have a room for ligands between vertically standing parallel walls termed Facial-wall and Rear-wall, which were separated by a distance corresponding to 1.5-Ring (grid) diameter size. The ligand sittings were stabilized through contacts with Facial-wall and the left-side borders of Template including specific Position 29 or Left-end after Trigger-residue initiated ligand-movement. Trigger-residue movement is suggested to force ligands to stay firmly in the active site and then to initiate CYP2C19 reactions. Simulation experiments for over 450 reactions of CYP2C19 ligands supported the system established.
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Affiliation(s)
- Yoshiya Yamamura
- Laboratory of Molecular Toxicology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan; Non-Clinical Regulatory Science, Applied Research & Operations, Astellas Pharma Inc., 21, Miyukigaoka, Tsukuba, Ibaraki, 305-8585, Japan
| | - Kouichi Yoshinari
- Laboratory of Molecular Toxicology, School of Pharmaceutical Sciences, University of Shizuoka, 52-1 Yada, Suruga-ku, Shizuoka, 422-8526, Japan
| | - Yasushi Yamazoe
- Division of Drug Metabolism and Molecular Toxicology, Graduate School of Pharmaceutical Sciences, Tohoku University, 6-3 Aramaki-Aoba, Aoba-ku, Sendai, 980-8578, Japan; Division of Risk Assessment, National Institute of Health Sciences, Tonomachi 3-25-26, Kawasaki-ku, Kawasaki, 210-9501, Japan.
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3
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Drug-Drug Interactions Involving Intestinal and Hepatic CYP1A Enzymes. Pharmaceutics 2020; 12:pharmaceutics12121201. [PMID: 33322313 PMCID: PMC7764576 DOI: 10.3390/pharmaceutics12121201] [Citation(s) in RCA: 25] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2020] [Revised: 12/02/2020] [Accepted: 12/08/2020] [Indexed: 12/29/2022] Open
Abstract
Cytochrome P450 (CYP) 1A enzymes are considerably expressed in the human intestine and liver and involved in the biotransformation of about 10% of marketed drugs. Despite this doubtless clinical relevance, CYP1A1 and CYP1A2 are still somewhat underestimated in terms of unwanted side effects and drug–drug interactions of their respective substrates. In contrast to this, many frequently prescribed drugs that are subjected to extensive CYP1A-mediated metabolism show a narrow therapeutic index and serious adverse drug reactions. Consequently, those drugs are vulnerable to any kind of inhibition or induction in the expression and function of CYP1A. However, available in vitro data are not necessarily predictive for the occurrence of clinically relevant drug–drug interactions. Thus, this review aims to provide an up-to-date summary on the expression, regulation, function, and drug–drug interactions of CYP1A enzymes in humans.
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Verlinden W, Van Mieghem E, Depauw L, Vanwolleghem T, Vonghia L, Weyler J, Driessen A, Callens D, Roosens L, Dirinck E, Verrijken A, Gaal LV, Francque S. Non-Alcoholic Steatohepatitis Decreases Microsomal Liver Function in the Absence of Fibrosis. Biomedicines 2020; 8:E546. [PMID: 33261113 PMCID: PMC7760673 DOI: 10.3390/biomedicines8120546] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/28/2020] [Revised: 11/23/2020] [Accepted: 11/26/2020] [Indexed: 12/21/2022] Open
Abstract
The incidence of non-alcoholic fatty liver disease (NAFLD) is rising across the globe, with the presence of steatohepatitis leading to a more aggressive clinical course. Currently, the diagnosis of non-alcoholic steatohepatitis (NASH) is based on histology, though with the high prevalence of NAFLD, a non-invasive method is needed. The 13C-aminopyrine breath test (ABT) evaluates the microsomal liver function and could be a potential candidate. We aimed to evaluate a potential change in liver function in NASH patients and to evaluate the diagnostic power of ABT to detect NASH. We performed a retrospective analysis on patients suspected of NAFLD who underwent a liver biopsy and ABT. 440 patients were included. ABT did not decrease in patients with isolated liver steatosis but decreased significantly in the presence of NASH without fibrosis and decreased even further with the presence of significant fibrosis. The predictive power of ABT as a single test for NASH was low but improved in combination with ALT and ultrasonographic steatosis. We conclude that microsomal liver function of patients with NASH is significantly decreased, even in the absence of fibrosis. The ABT is thus a valuable tool in assessing the presence of NASH; and could be used as a supplementary diagnostic tool in clinical practice.
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Affiliation(s)
- Wim Verlinden
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology and Hepatology, University of Antwerp, 2610 Antwerp, Belgium; (E.V.M.); (L.D.); (T.V.); (L.V.); (J.W.)
- Department of Gastroenterology and Hepatology, Antwerp University Hospital, 2650 Antwerp, Belgium
| | - Eugénie Van Mieghem
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology and Hepatology, University of Antwerp, 2610 Antwerp, Belgium; (E.V.M.); (L.D.); (T.V.); (L.V.); (J.W.)
| | - Laura Depauw
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology and Hepatology, University of Antwerp, 2610 Antwerp, Belgium; (E.V.M.); (L.D.); (T.V.); (L.V.); (J.W.)
| | - Thomas Vanwolleghem
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology and Hepatology, University of Antwerp, 2610 Antwerp, Belgium; (E.V.M.); (L.D.); (T.V.); (L.V.); (J.W.)
- Department of Gastroenterology and Hepatology, Antwerp University Hospital, 2650 Antwerp, Belgium
| | - Luisa Vonghia
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology and Hepatology, University of Antwerp, 2610 Antwerp, Belgium; (E.V.M.); (L.D.); (T.V.); (L.V.); (J.W.)
- Department of Gastroenterology and Hepatology, Antwerp University Hospital, 2650 Antwerp, Belgium
| | - Jonas Weyler
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology and Hepatology, University of Antwerp, 2610 Antwerp, Belgium; (E.V.M.); (L.D.); (T.V.); (L.V.); (J.W.)
- Department of Gastroenterology and Hepatology, Antwerp University Hospital, 2650 Antwerp, Belgium
| | - Ann Driessen
- Department of Pathology, Antwerp University Hospital, 2650 Antwerp, Belgium;
| | - Dirk Callens
- Department of Clinical Biology, Antwerp University Hospital, 2650 Antwerp, Belgium; (D.C.); (L.R.)
| | - Laurence Roosens
- Department of Clinical Biology, Antwerp University Hospital, 2650 Antwerp, Belgium; (D.C.); (L.R.)
| | - Eveline Dirinck
- Department of Endocrinology, Diabetology and Metabolism, Antwerp University Hospital, 2650 Antwerp, Belgium; (E.D.); (A.V.); (L.V.G.)
| | - An Verrijken
- Department of Endocrinology, Diabetology and Metabolism, Antwerp University Hospital, 2650 Antwerp, Belgium; (E.D.); (A.V.); (L.V.G.)
| | - Luc Van Gaal
- Department of Endocrinology, Diabetology and Metabolism, Antwerp University Hospital, 2650 Antwerp, Belgium; (E.D.); (A.V.); (L.V.G.)
| | - Sven Francque
- Laboratory of Experimental Medicine and Pediatrics, Division of Gastroenterology and Hepatology, University of Antwerp, 2610 Antwerp, Belgium; (E.V.M.); (L.D.); (T.V.); (L.V.); (J.W.)
- Department of Gastroenterology and Hepatology, Antwerp University Hospital, 2650 Antwerp, Belgium
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Galli U, Tron GC, Purghè B, Grosa G, Aprile S. Metabolic Fate of the Isocyanide Moiety: Are Isocyanides Pharmacophore Groups Neglected by Medicinal Chemists? Chem Res Toxicol 2020; 33:955-966. [PMID: 32212628 DOI: 10.1021/acs.chemrestox.9b00504] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Despite the isolation of hundreds of bioactive isocyanides from terrestrial fungi and bacteria as well as marine organisms, the isocyanide functionality has so far received little attention from a medicinal chemistry standpoint. The widespread tenet that isocyanides are chemically and metabolically unstable has restricted bioactivity studies to their antifouling properties and technical applications. In order to confirm or refute this idea, the hepatic metabolism of six model isocyanides was investigated. Aromatic and primary isocyanides turned out to be unstable and metabolically labile, but secondary and tertiary isocyanides resisted metabolization, showing, in some cases, cytochrome P450 inhibitory properties. The potential therefore exists for the secondary and tertiary isocyanides to qualify them as pharmacophore groups, in particular as war-heads for metalloenzyme inhibition because of their potent metal-coordinating properties.
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Affiliation(s)
- Ubaldina Galli
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale, Novara, 28100, Italy
| | - Gian Cesare Tron
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale, Novara, 28100, Italy
| | - Beatrice Purghè
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale, Novara, 28100, Italy
| | - Giorgio Grosa
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale, Novara, 28100, Italy
| | - Silvio Aprile
- Department of Pharmaceutical Sciences, Università del Piemonte Orientale, Novara, 28100, Italy
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Aprile S, Galli U, Tron GC, Del Grosso E, Travelli C, Grosa G. Data on metabolic stability, aqueous solubility and CYP inhibition of novel triazole-based nicotinamide phosphoribosyltransferase (NAMPT) inhibitors. Data Brief 2020; 28:105034. [PMID: 32226807 PMCID: PMC7093798 DOI: 10.1016/j.dib.2019.105034] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/28/2019] [Revised: 11/14/2019] [Accepted: 12/12/2019] [Indexed: 12/05/2022] Open
Abstract
In the related research article, entitled “Identification of novel triazole-based nicotinamide phosphoribosyltransferase (NAMPT) inhibitors endowed with antiproliferative and antiinflammatory activity” [1], we reported the in vitro hepatic metabolism data for compounds 30c, 48b, and 31b (here named as E5, A6, and T1), in comparison with the reference compounds GPP78 and FK866 [1–3]. In this article, we retrieved the available data about the hepatic microsomal stability and metabolites structural characterization of the entire library of triazole-based NAMPT inhibitors, also implementing the given information with data regarding aqueous solubility and CYP inhibition. Compounds are divided in subclasses based on the hydrolytic resistant groups replacing the amide function of GPP78 [1, 2].
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Affiliation(s)
- Silvio Aprile
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Largo Donegani 2, 28100, Novara, Italy
- Corresponding author.
| | - Ubaldina Galli
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Largo Donegani 2, 28100, Novara, Italy
| | - Gian Cesare Tron
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Largo Donegani 2, 28100, Novara, Italy
| | - Erika Del Grosso
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Largo Donegani 2, 28100, Novara, Italy
| | - Cristina Travelli
- Department of Pharmaceutical Sciences, University of Pavia, Viale Taramelli 12, 27100, Pavia, Italy
| | - Giorgio Grosa
- Department of Pharmaceutical Sciences, University of Piemonte Orientale, Largo Donegani 2, 28100, Novara, Italy
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Lykke Eriksen P, Sørensen M, Grønbæk H, Hamilton-Dutoit S, Vilstrup H, Thomsen KL. Non-alcoholic fatty liver disease causes dissociated changes in metabolic liver functions. Clin Res Hepatol Gastroenterol 2019; 43:551-560. [PMID: 30770336 DOI: 10.1016/j.clinre.2019.01.001] [Citation(s) in RCA: 23] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/05/2018] [Revised: 01/02/2019] [Accepted: 01/10/2019] [Indexed: 02/04/2023]
Abstract
BACKGROUND Non-alcoholic fatty liver disease (NAFLD) is a major health concern affecting 25% of the world's population. It is generally held that a fatty liver does not influence liver function, but quantitative measurements of metabolic liver functions have not been systematically performed. We aimed to study selected hepatocellular metabolic functions in patients with different stages of NAFLD. METHODS Twenty-five non-diabetic, biopsy-proven NAFLD patients [12 with simple steatosis; 13 with non-alcoholic steatohepatitis (NASH)] and ten healthy controls were included in a cross-sectional study. Hepatocyte cytosolic function was assessed by the galactose elimination capacity (GEC), mitochondrial-cytosolic metabolic capacity by the functional hepatic nitrogen clearance (FHNC), microsomal function by the aminopyrine breath test, and excretory liver function by indocyanine green (ICG) elimination. RESULTS GEC was 20% higher in NAFLD than in controls [3.15 mmol/min (2.9-3.41) vs. 2.62 (2.32-2.93); P = 0.02]. FHNC was 30% lower in NAFLD [23.3 L/h (18.7-28.9) vs. 33.1 (28.9-37.9); P = 0.04], more so in simple steatosis [19.1 L/h (13.9-26.2); P = 0.003] and non-significantly in NASH [27.9 L/h (20.6-37.8); P = 0.19]. Aminopyrine metabolism was 25% lower in simple steatosis [8.9% (7.0-10.7)] and 50% lower in NASH [6.0% (4.5-7.5)] than in controls [11.9% (9.3-12.8)] (P < 0.001). ICG elimination was intact. CONCLUSIONS The hepatocellular metabolic functions were altered in a manner that was dissociated both by different effects on different liver functions and by different effects of different stages of NAFLD. Thus, NAFLD has widespread consequences for metabolic liver function, even in simple steatosis.
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Affiliation(s)
- Peter Lykke Eriksen
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Palle Juul-Jensens boulevard 99, Aarhus, Denmark.
| | - Michael Sørensen
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Palle Juul-Jensens boulevard 99, Aarhus, Denmark
| | - Henning Grønbæk
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Palle Juul-Jensens boulevard 99, Aarhus, Denmark
| | - Stephen Hamilton-Dutoit
- Institute of Pathology, Aarhus University Hospital, Palle Juul-Jensens boulevard 99, Aarhus, Denmark
| | - Hendrik Vilstrup
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Palle Juul-Jensens boulevard 99, Aarhus, Denmark
| | - Karen Louise Thomsen
- Department of Hepatology and Gastroenterology, Aarhus University Hospital, Palle Juul-Jensens boulevard 99, Aarhus, Denmark
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Niwa T, Morimoto M, Hirai T, Hata T, Hayashi M, Imagawa Y. Effect of penicillin-based antibiotics, amoxicillin, ampicillin, and piperacillin, on drug-metabolizing activities of human hepatic cytochromes P450. J Toxicol Sci 2016; 41:143-6. [PMID: 26763401 DOI: 10.2131/jts.41.143] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/02/2022]
Abstract
The effects of three kinds of penicillin-based antibiotics, amoxicillin, ampicillin, and piperacillin, on drug-metabolizing activity of human hepatic cytochrome P450 (P450 or CYP) were investigated. Metabolic activities of P450s expressed in recombinant Escherichia coli at substrate concentrations around the Michaelis constant were compared in the presence or absence of the antibiotics. Amoxicillin, ampicillin, and piperacillin at 0.5 or 1 mM concentrations neither inhibited nor stimulated CYP2C9-mediated tolbutamide methylhydroxylation, CYP2D6-mediated dopamine formation from p-tyramine, or CYP3A4- or CYP3A5-mediated testosterone 6β-hydroxylation. However, amoxicillin and piperacillin inhibited CYP2C8-mediated aminopyrine N-demethylation at 50% inhibitory concentration of 0.83 and 1.14 mM, respectively. These results suggest that piperacillin might inhibit CYP2C8 clinically, although the interactions between these three penicillin-based antibiotics and other drugs that are metabolized by P450s investigated would not be clinically significant.
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Hedrich WD, Hassan HE, Wang H. Insights into CYP2B6-mediated drug-drug interactions. Acta Pharm Sin B 2016; 6:413-425. [PMID: 27709010 PMCID: PMC5045548 DOI: 10.1016/j.apsb.2016.07.016] [Citation(s) in RCA: 86] [Impact Index Per Article: 10.8] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/29/2016] [Revised: 05/18/2016] [Accepted: 05/27/2016] [Indexed: 01/11/2023] Open
Abstract
Mounting evidence demonstrates that CYP2B6 plays a much larger role in human drug metabolism than was previously believed. The discovery of multiple important substrates of CYP2B6 as well as polymorphic differences has sparked increasing interest in the genetic and xenobiotic factors contributing to the expression and function of the enzyme. The expression of CYP2B6 is regulated primarily by the xenobiotic receptors constitutive androstane receptor (CAR) and pregnane X receptor (PXR) in the liver. In addition to CYP2B6, these receptors also mediate the inductive expression of CYP3A4, and a number of important phase II enzymes and drug transporters. CYP2B6 has been demonstrated to play a role in the metabolism of 2%–10% of clinically used drugs including widely used antineoplastic agents cyclophosphamide and ifosfamide, anesthetics propofol and ketamine, synthetic opioids pethidine and methadone, and the antiretrovirals nevirapine and efavirenz, among others. Significant inter-individual variability in the expression and function of the human CYP2B6 gene exists and can result in altered clinical outcomes in patients receiving treatment with CYP2B6-substrate drugs. These variances arise from a number of sources including genetic polymorphism, and xenobiotic intervention. In this review, we will provide an overview of the key players in CYP2B6 expression and function and highlight recent advances made in assessing clinical ramifications of important CYP2B6-mediated drug–drug interactions.
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Key Words
- 4-OH-CPA, 4-hydroxycyclophosphamide
- C/EBP, CCAAT/enhancer-binding protein
- CAR
- CAR, constitutive androstane receptor
- CHOP, cyclophosphamide–doxorubicin–vincristine–prednisone
- CITCO, (6-(4-chlorophenyl)imidazo[2,1-b][1,3]thiazole-5-carbaldehyde-O-(3,4-dichlorobenzyl)oxime)
- COUP-TF, chicken ovalbumin upstream promoter-transcription factor
- CPA, cyclophosphamide
- CYP, cytochrome P450
- CYP2B6
- Cyclophosphamide
- DDI, drug–drug interaction
- DEX, dexamethasone
- Drug–drug interaction
- E2, estradiol
- EFV, efavirenz
- ERE, estrogen responsive element
- Efavirenz
- GR, glucocorticoid receptor
- GRE, glucocorticoid responsive element
- HAART, highly active antiretroviral therapy
- HNF, hepatocyte nuclear factor
- IFA, Ifosfamide
- MAOI, monoamine oxidase inhibitor
- NNRTI, non-nucleotide reverse-transcriptase inhibitor
- NR1/2, nuclear receptor binding site 1/2
- NVP, nevirapine
- PB, phenobarbital
- PBREM, phenobarbital-responsive enhancer module
- PCN, pregnenolone 16 alpha-carbonitrile
- PXR
- PXR, pregnane X receptor
- Polymorphism
- RIF, rifampin
- SNP, single nucleotide polymorphism
- TCPOBOP, 1,4-bis[3,5-dichloropyridyloxy]benzene
- UGT, UDP-glucuronosyl transferase
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Affiliation(s)
| | | | - Hongbing Wang
- Corresponding author at: Department of Pharmaceutical Sciences, University of Maryland School of Pharmacy, 20 Penn Street, Baltimore, MD 21201, USA. Tel.: +1 410 706 1280; fax: +1 410 706 5017.
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Backman JT, Filppula AM, Niemi M, Neuvonen PJ. Role of Cytochrome P450 2C8 in Drug Metabolism and Interactions. Pharmacol Rev 2016; 68:168-241. [PMID: 26721703 DOI: 10.1124/pr.115.011411] [Citation(s) in RCA: 142] [Impact Index Per Article: 17.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
During the last 10-15 years, cytochrome P450 (CYP) 2C8 has emerged as an important drug-metabolizing enzyme. CYP2C8 is highly expressed in human liver and is known to metabolize more than 100 drugs. CYP2C8 substrate drugs include amodiaquine, cerivastatin, dasabuvir, enzalutamide, imatinib, loperamide, montelukast, paclitaxel, pioglitazone, repaglinide, and rosiglitazone, and the number is increasing. Similarly, many drugs have been identified as CYP2C8 inhibitors or inducers. In vivo, already a small dose of gemfibrozil, i.e., 10% of its therapeutic dose, is a strong, irreversible inhibitor of CYP2C8. Interestingly, recent findings indicate that the acyl-β-glucuronides of gemfibrozil and clopidogrel cause metabolism-dependent inactivation of CYP2C8, leading to a strong potential for drug interactions. Also several other glucuronide metabolites interact with CYP2C8 as substrates or inhibitors, suggesting that an interplay between CYP2C8 and glucuronides is common. Lack of fully selective and safe probe substrates, inhibitors, and inducers challenges execution and interpretation of drug-drug interaction studies in humans. Apart from drug-drug interactions, some CYP2C8 genetic variants are associated with altered CYP2C8 activity and exhibit significant interethnic frequency differences. Herein, we review the current knowledge on substrates, inhibitors, inducers, and pharmacogenetics of CYP2C8, as well as its role in clinically relevant drug interactions. In addition, implications for selection of CYP2C8 marker and perpetrator drugs to investigate CYP2C8-mediated drug metabolism and interactions in preclinical and clinical studies are discussed.
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Affiliation(s)
- Janne T Backman
- Department of Clinical Pharmacology, University of Helsinki (J.T.B., A.M.F., M.N., P.J.N.), and Helsinki University Hospital, Helsinki, Finland (J.T.B., M.N., P.J.N.)
| | - Anne M Filppula
- Department of Clinical Pharmacology, University of Helsinki (J.T.B., A.M.F., M.N., P.J.N.), and Helsinki University Hospital, Helsinki, Finland (J.T.B., M.N., P.J.N.)
| | - Mikko Niemi
- Department of Clinical Pharmacology, University of Helsinki (J.T.B., A.M.F., M.N., P.J.N.), and Helsinki University Hospital, Helsinki, Finland (J.T.B., M.N., P.J.N.)
| | - Pertti J Neuvonen
- Department of Clinical Pharmacology, University of Helsinki (J.T.B., A.M.F., M.N., P.J.N.), and Helsinki University Hospital, Helsinki, Finland (J.T.B., M.N., P.J.N.)
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11
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De Kesel PMM, Lambert WE, Stove CP. Alternative Sampling Strategies for Cytochrome P450 Phenotyping. Clin Pharmacokinet 2015; 55:169-84. [DOI: 10.1007/s40262-015-0306-y] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
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12
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Ford KA, Ryslik G, Sodhi J, Halladay J, Diaz D, Dambach D, Masuda M. Computational predictions of the site of metabolism of cytochrome P450 2D6 substrates: comparative analysis, molecular docking, bioactivation and toxicological implications. Drug Metab Rev 2015; 47:291-319. [DOI: 10.3109/03602532.2015.1047026] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
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13
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Martínez C, Andreu I, Amo G, Miranda MA, Esguevillas G, Torres MJ, Blanca-López N, Blanca M, García-Martín E, Agúndez JA. Gender and functional CYP2C and NAT2 polymorphisms determine the metabolic profile of metamizole. Biochem Pharmacol 2014; 92:457-66. [DOI: 10.1016/j.bcp.2014.09.005] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2014] [Revised: 09/07/2014] [Accepted: 09/08/2014] [Indexed: 12/23/2022]
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Massarotti A, Aprile S, Mercalli V, Del Grosso E, Grosa G, Sorba G, Tron GC. Are 1,4- and 1,5-disubstituted 1,2,3-triazoles good pharmacophoric groups? ChemMedChem 2014; 9:2497-508. [PMID: 25079879 DOI: 10.1002/cmdc.201402233] [Citation(s) in RCA: 111] [Impact Index Per Article: 11.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2014] [Indexed: 01/09/2023]
Abstract
Over the last decade, 1,2,3-triazoles have received increasing attention in medicinal chemistry thanks to the discovery of the highly useful and widely applicable 1,3-dipolar cycloaddition reaction between azides and alkynes (click chemistry) catalyzed by copper salts and ruthenium complexes. After a decade of medicinal chemistry research on 1,2,3-triazoles, we feel that the time is ripe to demonstrate the real ability of this heterocycle to participate in important and pivotal binding interactions with biological targets while maintaining a good pharmacokinetic profile. In this study, we retrieved and analyzed X-ray crystal structures of complexes between 1,2,3-triazoles and either proteins or DNA to understand the pharmacophoric role of the triazole. Furthermore, the metabolic stability, the capacity to inhibit cytochromes, and the contribution of 1,2,3-triazoles to the overall aqueous solubility of compounds containing them have been analyzed. This information should furnish fresh insight for medicinal chemists in the design of novel bioactive molecules that contain the triazole nucleus.
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Affiliation(s)
- Alberto Massarotti
- Dipartimento di Scienze del Farmaco, Università degli Studi del Piemonte Orientale "A. Avogadro", L.go Donegani 2, 28100 Novara (Italy).
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15
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Pijls KE, de Vries H, Nikkessen S, Bast A, Wodzig WKWH, Koek GH. Critical appraisal of 13C breath tests for microsomal liver function: aminopyrine revisited. Liver Int 2014; 34:487-94. [PMID: 24428683 DOI: 10.1111/liv.12451] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 05/21/2013] [Accepted: 12/15/2013] [Indexed: 12/17/2022]
Abstract
As liver diseases are a major health problem and especially the incidence of metabolic liver diseases like non-alcoholic fatty liver disease (NAFLD) is rising, the demand for non-invasive tests is growing to replace liver biopsy. Non-invasive tests such as carbon-labelled breath tests can provide a valuable contribution to the evaluation of metabolic liver function. This review aims to critically appraise the value of the (13) C-labelled microsomal breath tests for the evaluation of metabolic liver function, and to discuss the role of cytochrome P450 enzymes in the metabolism of the different probe drugs, especially of aminopyrine. Although a number of different probe drugs have been used in breath tests, the perfect drug to assess the functional metabolic capacity of the liver has not been found. Data suggest that both the (13) C(2) -aminopyrine and the (13) C-methacetin breath test can play a role in assessing the capacity of the microsomal liver function and may be useful in the follow-up of patients with chronic liver diseases. Furthermore, CYP2C19 seems to be an important enzyme in the N-demethylation of aminopyrine, and polymorphisms in this gene may influence breath test values, which should be kept in mind when performing the (13) C(2) -aminopyrine breath test in clinical practice.
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Affiliation(s)
- Kirsten E Pijls
- Division of Gastroenterology and Hepatology, Department of Internal Medicine, Maastricht University Medical Center, Maastricht, the Netherlands
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16
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Turpeinen M, Zanger UM. Cytochrome P450 2B6: function, genetics, and clinical relevance. ACTA ACUST UNITED AC 2013; 27:185-97. [PMID: 23152403 DOI: 10.1515/dmdi-2012-0027] [Citation(s) in RCA: 67] [Impact Index Per Article: 6.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2012] [Accepted: 10/15/2012] [Indexed: 12/17/2022]
Abstract
Cytochrome P450 (CYP) 2B6 belongs to the set of important hepatic drug-metabolizing CYPs. It makes up roughly 3%-6% of total hepatic CYP content and metabolizes several pharmaceuticals including bupropion, efavirenz, cyclophosphamide, pethidine, ketamine and propofol. The enzyme is susceptible to drug-drug interactions by enzyme induction and inhibition. In addition to drugs, CYP2B6 is able to both detoxify and bioactivate a number of procarcinogens and environmental agents including pesticides and herbicides. There is an extensive interindividual variability in the expression of CYP2B6, which is in part explained by extensive genetic polymorphism. CYP2B6 is one of the most polymorphic CYP genes in humans with over 100 described SNPs, numerous complex haplotypes and distinct ethnic and racial frequencies. This review summarizes the basic properties of CYP2B6 and the main characteristics of clinical relevance.
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Affiliation(s)
- Miia Turpeinen
- Department of Pharmacology and Toxicology, University of Oulu, Oulu, Finland.
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17
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Zhou SF, Wang B, Yang LP, Liu JP. Structure, function, regulation and polymorphism and the clinical significance of human cytochrome P450 1A2. Drug Metab Rev 2010; 42:268-354. [PMID: 19961320 DOI: 10.3109/03602530903286476] [Citation(s) in RCA: 183] [Impact Index Per Article: 13.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Human CYP1A2 is one of the major CYPs in human liver and metabolizes a number of clinical drugs (e.g., clozapine, tacrine, tizanidine, and theophylline; n > 110), a number of procarcinogens (e.g., benzo[a]pyrene and aromatic amines), and several important endogenous compounds (e.g., steroids). CYP1A2 is subject to reversible and/or irreversible inhibition by a number of drugs, natural substances, and other compounds. The CYP1A gene cluster has been mapped on to chromosome 15q24.1, with close link between CYP1A1 and 1A2 sharing a common 5'-flanking region. The human CYP1A2 gene spans almost 7.8 kb comprising seven exons and six introns and codes a 515-residue protein with a molecular mass of 58,294 Da. The recently resolved CYP1A2 structure has a relatively compact, planar active site cavity that is highly adapted for the size and shape of its substrates. The architecture of the active site of 1A2 is characterized by multiple residues on helices F and I that constitutes two parallel substrate binding platforms on either side of the cavity. A large interindividual variability in the expression and activity of CYP1A2 has been observed, which is largely caused by genetic, epigenetic and environmental factors (e.g., smoking). CYP1A2 is primarily regulated by the aromatic hydrocarbon receptor (AhR) and CYP1A2 is induced through AhR-mediated transactivation following ligand binding and nuclear translocation. Induction or inhibition of CYP1A2 may provide partial explanation for some clinical drug interactions. To date, more than 15 variant alleles and a series of subvariants of the CYP1A2 gene have been identified and some of them have been associated with altered drug clearance and response and disease susceptibility. Further studies are warranted to explore the clinical and toxicological significance of altered CYP1A2 expression and activity caused by genetic, epigenetic, and environmental factors.
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Affiliation(s)
- Shu-Feng Zhou
- Discpline of Chinese Medicine, School of Health Sciences, RMIT University, Bundoora, Victoria 3083, Australia.
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18
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At the crossroads of steroid hormone biosynthesis: the role, substrate specificity and evolutionary development of CYP17. BIOCHIMICA ET BIOPHYSICA ACTA-PROTEINS AND PROTEOMICS 2010; 1814:200-9. [PMID: 20619364 DOI: 10.1016/j.bbapap.2010.06.021] [Citation(s) in RCA: 84] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 04/01/2010] [Revised: 05/28/2010] [Accepted: 06/26/2010] [Indexed: 11/22/2022]
Abstract
Cytochrome P450s play critical roles in the metabolism of various bioactive compounds. One of the crucial functions of cytochrome P450s in Chordata is in the biosynthesis of steroid hormones. Steroid 17alpha-hydroxylase/17,20-lyase (CYP17) is localized in endoplasmic reticulum membranes of steroidogenic cells. CYP17 catalyzes the 17alpha-hydroxylation reaction of delta4-C₂₁ steroids (progesterone derivatives) and delta5-C₂₁ steroids (pregnenolone derivatives) as well as the 17,20-lyase reaction producing C₁₉-steroids, a key branch point in steroid hormone biosynthesis. Depending on CYP17 activity, the steroid hormone biosynthesis pathway is directed to either the formation of mineralocorticoids and glucocorticoids or sex hormones. In the present review, the current information on CYP17 is analyzed and discussed.
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Zhou SF, Liu JP, Chowbay B. Polymorphism of human cytochrome P450 enzymes and its clinical impact. Drug Metab Rev 2009; 41:89-295. [PMID: 19514967 DOI: 10.1080/03602530902843483] [Citation(s) in RCA: 502] [Impact Index Per Article: 33.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Pharmacogenetics is the study of how interindividual variations in the DNA sequence of specific genes affect drug response. This article highlights current pharmacogenetic knowledge on important human drug-metabolizing cytochrome P450s (CYPs) to understand the large interindividual variability in drug clearance and responses in clinical practice. The human CYP superfamily contains 57 functional genes and 58 pseudogenes, with members of the 1, 2, and 3 families playing an important role in the metabolism of therapeutic drugs, other xenobiotics, and some endogenous compounds. Polymorphisms in the CYP family may have had the most impact on the fate of therapeutic drugs. CYP2D6, 2C19, and 2C9 polymorphisms account for the most frequent variations in phase I metabolism of drugs, since almost 80% of drugs in use today are metabolized by these enzymes. Approximately 5-14% of Caucasians, 0-5% Africans, and 0-1% of Asians lack CYP2D6 activity, and these individuals are known as poor metabolizers. CYP2C9 is another clinically significant enzyme that demonstrates multiple genetic variants with a potentially functional impact on the efficacy and adverse effects of drugs that are mainly eliminated by this enzyme. Studies into the CYP2C9 polymorphism have highlighted the importance of the CYP2C9*2 and *3 alleles. Extensive polymorphism also occurs in other CYP genes, such as CYP1A1, 2A6, 2A13, 2C8, 3A4, and 3A5. Since several of these CYPs (e.g., CYP1A1 and 1A2) play a role in the bioactivation of many procarcinogens, polymorphisms of these enzymes may contribute to the variable susceptibility to carcinogenesis. The distribution of the common variant alleles of CYP genes varies among different ethnic populations. Pharmacogenetics has the potential to achieve optimal quality use of medicines, and to improve the efficacy and safety of both prospective and currently available drugs. Further studies are warranted to explore the gene-dose, gene-concentration, and gene-response relationships for these important drug-metabolizing CYPs.
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Affiliation(s)
- Shu-Feng Zhou
- School of Health Sciences, RMIT University, Bundoora, Victoria, Australia.
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20
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Wang H, Tompkins LM. CYP2B6: new insights into a historically overlooked cytochrome P450 isozyme. Curr Drug Metab 2008; 9:598-610. [PMID: 18781911 DOI: 10.2174/138920008785821710] [Citation(s) in RCA: 226] [Impact Index Per Article: 14.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/15/2022]
Abstract
Human CYP2B6 has been thought to account for a minor portion (<1%) of total hepatic cytochrome P450 (CYP) content and to have a minor function in human drug metabolism. Recent studies, however, indicate that the average relative contribution of CYP2B6 to total hepatic CYP content ranges from 2% to 10%. An increased interest in CYP2B6 research has been stimulated by the identification of an ever-increasing substrate list for this enzyme, polymorphic and ethnic variations in expression levels, and evidence for cross-regulation with CYP3A4, UGT1A1 and several hepatic drug transporters by the nuclear receptors pregnane X receptor and constitutive androstane receptor. Moreover, 20- to 250-fold interindividual variation in CYP2B6 expression has been demonstrated, presumably due to transcriptional regulation and polymorphisms. These individual differences may result in variable systemic exposure to drugs metabolized by CYP2B6, including the antineoplastics cyclophosphamide and ifosfamide, the antiretrovirals nevirapine and efavirenz, the anesthetics propofol and ketamine, the synthetic opioid methadone, and the anti-Parkinsonian selegiline. The potential clinical significance of CYP2B6 further enforces the need for a comprehensive review of this xenobiotic metabolizing enzyme. This communication summarizes recent advances in our understanding of this traditionally neglected enzyme and provides an overall picture of CYP2B6 with respect to expression, localization, substrate-specificity, inhibition, regulation, polymorphisms and clinical significance. Emphasis is given to nuclear receptor mediated transcriptional regulation, genetic polymorphisms, and their clinical significance.
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Affiliation(s)
- Hongbing Wang
- Department of Pharmaceutical Sciences, School of Pharmacy, University of Maryland at Baltimore, 20 Penn Street, Baltimore, MD 21201, USA.
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21
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Brown CM, Reisfeld B, Mayeno AN. Cytochromes P450: A Structure-Based Summary of Biotransformations Using Representative Substrates. Drug Metab Rev 2008. [DOI: 10.1080/03602530701836662] [Citation(s) in RCA: 55] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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22
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Mayer RT, Dolence EK, Mayer GE. A Real-Time Fluorescence Assay for Measuring N-Dealkylation. Drug Metab Dispos 2006; 35:103-9. [PMID: 17035601 DOI: 10.1124/dmd.106.011601] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022] Open
Abstract
A real-time fluorescence assay system using a series of 9-N-(alkylamino)acridine derivatives (methyl, ethyl, n-propyl, n-butyl, n-pentyl, and benzyl) that are N-dealkylated to 9-aminoacridine (9AA) is described. The product, 9AA, is approximately 27-fold more fluorescent than the substrates using excitation and emission wavelengths of 405 and 455 nm, respectively. Tests using expressed CYP1A1, 1A2, 3A4, 3A5, 1B1, 2C9, 2C19, and 2D6 indicated that N-dealkylase activity is specific for CYP1A1 and CYP2D6. CYP2D6 N-dealkylated methyl, ethyl, n-propyl, and n-butyl substrates, whereas CYP1A1 N-dealkylated these plus the n-pentyl derivative. Activities using 5 microM 9-N-(alkylamino)acridine substrates ranged from 0.1 to 0.9 pmol 9AA/min/pmol P450. Kinetic constants for CYP1A1 N-dealkylation of the 9-N-(methylamino)acridine (MAA) and 9-N-(ethylamino)acridine (EAA) were K(m) 1.09 +/- 0.68 and 0.35 +/- 0.21 microM and the V(max) 61.9 +/- 48.5 and 113.8 +/- 8.4 pmol 9AA/min/pmol CYP1A1, respectively. Kinetic constants for CYP2D6 N-dealkylation of MAA and EAA were K(m) 7.9 +/- 5.4 and 3.2 +/- 1.6 microM, and V(max) 501 +/- 35.4 and 702.7 +/- 257 pmol 9AA/min/pmol CYP2D6, respectively. The experimental binding energies (DeltaG(bind)) were calculated for MAA with CYP1A1 and CYP2D6 to be -8.266 and -7.074 kcal/mol, respectively. The DeltaG(bind) values for EAA with CYP1A1 and CYP2D6 were -8.950 and -7.618 kcal/mol, respectively. The substrates were suitable for monitoring N-dealkylase activity in microsomal preparations (human, rat, and monkey hepatic preparations) and human hepatocellular carcinoma cell suspensions. Assays were conducted by monitoring reactions either in 96-well microtiter plates using a fluorescence plate reader or in cuvettes using a spectrofluorimeter.
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Affiliation(s)
- Richard T Mayer
- Arthropod-Borne Animal Diseases Research Laboratory, USDA, ARS, College of Agriculture, Department 3354, 1000 East University Avenue, Laramie WY 82071, USA.
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23
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Giannini EG, Savarino V, Testa R. Monitoring cytochrome P-450 activity during rabeprazole treatment in patients with gastresophageal reflux disease. Dig Dis Sci 2006; 51:1602-6. [PMID: 16927149 DOI: 10.1007/s10620-005-9035-7] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/20/2005] [Accepted: 08/24/2005] [Indexed: 01/16/2023]
Abstract
Proton pump inhibitors (PPIs) are the cornerstone in the treatment of gastresophageal reflux disease (GORD). PPIs are metabolized by the hepatic cytochrome P-450 enzymes (CYP-450). Rabeprazole is a PPI whose metabolism shows fewer interactions compared to other PPIs. In this study we evaluated the influence of rabeprazole administration on hepatic CYP-450 activity as measured by the (13)C-aminopyrine breath test ((13)C-ABT) in a group of patients with GORD. (13)C-ABT was performed on five GORD patients both before and after 1 week of rabeprazole administration (20 mg, b.i.d.). Pretreatment (13)C-ABT results were compared to posttreatment results. Pre- and posttreatment (13)C-ABT results for patients were compared to those obtained in five controls who did the test twice, with a 1-week interval in between. Before treatment, the (13)C-ABT results for the GORD patients did not significantly differ from those of healthy subjects. After treatment, we observed no significant modification of the (13)C-ABT in GORD patients compared to pretreatment values ((13)C-ABT %dose/hr, 10.56+/-1.31 versus 11.17+/-0.88; (13)C-ABT %cumulative dose, 8.08+/-1.11 versus 8.34+/-0.56). Posttreatment (13)C-ABT results were not significantly different from those obtained in controls at weekly repetition of the test. In patients with GORD, 1-week, full-dose rabeprazole does not display any significant interactions with CYP-450 activity.
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Affiliation(s)
- Edoardo G Giannini
- Gastroenterology Unit, Department of Internal Medicine, University of Genoa, Viale Benedetto XV, no. 6, 16132 Genoa, Italy.
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24
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Dasari VR, Anandatheerthavarada HK, Robin MA, Boopathi E, Biswas G, Fang JK, Nebert DW, Avadhani NG. Role of protein kinase C-mediated protein phosphorylation in mitochondrial translocation of mouse CYP1A1, which contains a non-canonical targeting signal. J Biol Chem 2006; 281:30834-47. [PMID: 16899466 DOI: 10.1074/jbc.m510725200] [Citation(s) in RCA: 28] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
A large number of mitochondrial proteins lack canonical mitochondrial-targeting signals. The bimodal transport of cytochromes P450 (CYPs) to endoplasmic reticulum and mitochondria (MT), reported previously by us, likely represents one mode of non-canonical protein targeting to MT. Herein, we have studied the mechanism of mouse MT-CYP1A1 targeting to gain insight into the regulatory features and evolutionary conservation of bimodal targeting mechanism. Mouse MT-CYP1A1 consists of two NH2-terminal-truncated molecular species, +91A1 and +331A1. Mutations Pro-2 --> Leu and Tyr-5 --> Leu, which increase the signal recognition particle (SRP) binding, diminished MT targeting of the protein in intact cells. By contrast, mutations Leu-7 --> Asn and Leu-17 --> Asn, which decreased SRP-binding affinity, enhanced MT targeting, thus suggesting that SRP binding is an important regulatory step that modulates bimodal targeting. Protein kinase C (PKC)-mediated phosphorylation of nascent chains at Thr-35 vastly decreased affinity for SRP binding suggesting an important regulatory step. In support of these results, COS cell transfection experiments show that phosphomimetic mutation Thr-35 --> Asp or induced cellular PKC caused increased CYP1A1 targeting to MT and correspondingly lower levels to the endoplasmic reticulum. Results suggest evolutionary conservation of chimeric signals and bimodal targeting of CYP1A1 in different species. The mouse MT-CYP1A1 is an extrinsic membrane protein, which exhibited high FDX1 plus FDXR-mediated N-demethylation of a number of tricyclic antidepressants, pain killers, anti-psychotics, and narcotics that are poor substrates for microsomal CYP1A1.
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Affiliation(s)
- Venkata Ramesh Dasari
- Department of Animal Biology and the Mari Lowe Center for Comparative Oncology, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, Pennsylvania 19104, USA
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25
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Li Lin A, Shangari N, Chan TS, Remirez D, O'Brien PJ. Herbal monoterpene alcohols inhibit propofol metabolism and prolong anesthesia time. Life Sci 2006; 79:21-9. [PMID: 16436284 DOI: 10.1016/j.lfs.2005.12.029] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/16/2005] [Revised: 12/06/2005] [Accepted: 12/14/2005] [Indexed: 01/03/2023]
Abstract
2,6-Diisopropylphenol (Propofol) is a short-acting intravenous anesthetic that is rapidly metabolized by glucuronidation and ring hydroxylation catalyzed by cytochrome P450. The goal of this research was to determine whether dietary monoterpene alcohols (MAs) could be used to prolong the anesthetic effect of propofol by inhibiting propofol metabolism in animals. Mice were injected intraperitoneally (i.p.) with MAs (100-200) mg/kg followed by the administration of 100 mg/kg propofol 40 min later via an i.p. injection. The time of the anesthesia of each mouse was recorded. It was found that (+/-)-borneol, (-)-carveol, trans-sobrerol, and menthol significantly extended the anesthetic effect of propofol (>3 times). The concentration of propofol in the mouse blood over time (up to 180 min) also increased in mice pre-treated with (-)-borneol, (-)-carveol, and trans-sobrerol. The volume of distribution of propofol decreased in the (-)-borneol (p<0.05), pre-treated group as compared to the propofol control group. Moreover, the maximum blood concentration of propofol and the concentration of propofol in the blood as indicated by the area under the curve were significantly increased in (-)-borneol and (-)-carveol pre-treated groups. Additional evidence using rat hepatocytes showed that (-)-borneol inhibited propofol glucuronidation whereas trans-sobrerol and (-)-carveol inhibited cytochrome P450 dependent microsomal aminopyrine N-demethylation. These results suggest that (-)-borneol extends propofol-induced anesthesia by inhibiting its glucuronidation in the mouse whereas trans-sobrerol (-)-carveol extends propofol-induced anesthesia by inhibiting P450 catalyzed propofol metabolism.
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Affiliation(s)
- Alison Li Lin
- Pharmaceutical Sciences Department, University of Toronto, 19 Russell Street, Toronto, Ontario, M5S 2S2, Canada
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26
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Lemahieu WPD, Maes BD, Verbeke K, Vanrenterghem Y. Impact of gastric acid suppressants on cytochrome P450 3A4 and P-glycoprotein: consequences for FK506 assimilation. Kidney Int 2005; 67:1152-60. [PMID: 15698457 DOI: 10.1111/j.1523-1755.2005.00182.x] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
Abstract
BACKGROUND Cytochrome P450 3A4 (CYP3A4) and P-glycoprotein (PGP) are important determinants of the oral bioavailability and clearance of tacrolimus. Cimetidine and omeprazole are known modulators of several CYPs in vitro. In the present study, the impact of cimetidine and omeprazole on tacrolimus exposure and on CYP3A4/PGP activity in vivo was examined. METHODS In a cohort of 48 renal transplant recipients who switched standard ulcer prophylaxis with 400 mg of cimetidine daily to 20 mg of omeprazole, dose/weight normalized trough levels of tacrolimus during a 5-day interval before and after switch were compared and further studied using multivariate analysis. In a cohort of 6 healthy volunteers, the effect of a 5-day course of ranitidine, cimetidine, and omeprazole on overall CYP, CYP3A4, and PGP activity in vivo was assessed with the (13)C-aminopyrin breath test and the combined per oral and intravenous (14)C-erythromycin breath and urine test. RESULTS Dose/weight normalized trough levels of tacrolimus decreased significantly (-15%) after switch from cimetidine to omeprazole. In healthy volunteers, a significant increase of intestinal CYP3A4 activity was observed after omeprazole, whereas no change was noted after cimetidine/ranitidine. Overall CYP activity was significantly decreased after cimetidine and remained unchanged after omeprazole/ranitidine. No effects on PGP or hepatic CYP3A4 were seen. CONCLUSION Switching treatment with cimetidine to omeprazole in renal transplant recipients is associated with a decrease of dose/weight normalized trough levels of tacrolimus. Studies in healthy volunteers suggest that this may be explained by an increase of intestinal CYP3A4 activity.
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Affiliation(s)
- Wim P D Lemahieu
- Division of Nephrology and Laboratory of Digestion and Absorption, Department of Medicine, University Hospital Gasthuisberg, University of Leuven, Leuven, Belgium
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27
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Di Marco A, Yao D, Laufer R. Demethylation of radiolabelled dextromethorphan in rat microsomes and intact hepatocytes. EUROPEAN JOURNAL OF BIOCHEMISTRY 2003; 270:3768-77. [PMID: 12950260 DOI: 10.1046/j.1432-1033.2003.03763.x] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
Liver microsomal preparations are routinely used to predict drug interactions that can occur in vivo as a result of inhibition of cytochrome P450 (CYP)-mediated metabolism. However, the concentration of free drug (substrate and inhibitor) at its intrahepatic site of action, a variable that cannot be directly measured, may be significantly different from that in microsomal incubation systems. Intact cells more closely reflect the environment to which CYP substrates and inhibitors are exposed in the liver, and it may therefore be desirable to assess the potential of a drug to cause CYP inhibition in isolated hepatocytes. The objective of this study was to compare the inhibitory potencies of a series of CYP2D inhibitors in rat liver microsomes and hepatocytes. For this, we developed an assay suitable for rapid analysis of CYP-mediated drug interactions in both systems, using radiolabelled dextromethorphan, a well-characterized probe substrate for enzymes of the CYP2D family. Dextromethorphan demethylation exhibited saturable kinetics in rat microsomes and hepatocytes, with apparent Km and Vmax values of 2.1 vs. 2.8 microM and 0.74 nM x min(-1) per mg microsomal protein vs. 0.11 nM x min(-1) per mg cellular protein, respectively. Quinine, quinidine, pyrilamine, propafenone, verapamil, ketoconazole and terfenadine inhibited dextromethorphan O-demethylation in rat liver microsomes and hepatocytes with IC50 values in the low micromolar range. Some of these compounds exhibited biphasic inhibition kinetics, indicative of interaction with more than one CYP2D isoform. Even though no important differences in inhibitory potencies were observed between the two systems, most inhibitors, including quinine and quinidine, displayed 2-3-fold lower IC50 in hepatocytes than in microsomes. The cell-associated concentrations of quinine and quinidine were found to be significantly higher than those in the extracellular medium, suggesting that intracellular accumulation may potentiate the effect of these compounds. Studies of CYP inhibition in intact hepatocytes may be warranted for compounds that concentrate in the liver as the result of cellular transport.
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Affiliation(s)
- Annalise Di Marco
- Istituto di Ricerche di Biologia Molecolare P. Angeletti, Merck Sharp and Dohme Research Laboratories, Rome, Italy
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28
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Moridani MY, Cheon SS, Khan S, O'Brien PJ. Metabolic activation of 3-hydroxyanisole by isolated rat hepatocytes. Chem Biol Interact 2003; 142:317-33. [PMID: 12453669 DOI: 10.1016/s0009-2797(02)00125-4] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
A tyrosinase-directed therapeutic approach for malignant melanoma therapy uses the depigmenting phenolic agents such as 4-hydroxyanisole (4-HA) to form cytotoxic o-quinones. However, renal and hepatic toxicity was reported as side effects in a recent 4-HA clinical trial. In search of novel therapeutics, the cytotoxicity of the isomers 4-HA, 3-HA and 2-HA were investigated. In the following, the order of the HAs induced hepatotoxicity in mice, as measured by increased in vivo plasma transaminase activity, or in isolated rat hepatocytes, as measured by trypan blue exclusion, was 3-HA > 2-HA > 4-HA. Hepatocyte GSH depletion preceded HA induced cytotoxicity and a 4-MC-SG conjugate was identified by LC/MS/MS mass spectrometry analysis when 3-HA was incubated with NADPH/microsomes/GSH. 3-HA induced hepatocyte GSH depletion or GSH depletion when 3-HA was incubated with NADPH/microsomes was prevented by CYP 2E1 inhibitors. Dicumarol (an NAD(P)H: quinone oxidoreductase inhibitor) potentiated 3-HA- or 4-methoxycatechol (4-MC) induced toxicity whereas sorbitol (an NADH generating nutrient) greatly prevented cytotoxicity indicating a quinone-mediated cytotoxic mechanism. Ethylendiamine (an o-quinone trap) largely prevented 3-HA and 4-MC-induced cytotoxicity indicating that o-quinone was involved in cytotoxicity. Dithiothreitol (DTT) greatly reduced 3-HA and 4-MC induced toxicity. The ferric chelator deferoxamine slightly decreased 3-HA and 4-MC induced cytotoxicity whereas the antioxidants pyrogallol or TEMPOL greatly prevented the toxicity suggesting that oxidative stress contributed to 3-HA induced cytotoxicity. In summary, ring hydroxylation but not O-demethylation/epoxidation seems to be the bioactivation pathway for 3-HA in rat liver. The cytotoxic mechanism for 3-HA and its metabolite 4-MC likely consists cellular protein alkylation and oxidative stress. These results suggest that 3-HA is not suitable for treatment of melanoma.
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Affiliation(s)
- Majid Y Moridani
- Faculty of Pharmacy, University of Toronto, 19 Russell Street, Toronto, Ont, Canada M5S 2S2
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Zhu-Ge J, Yu YN, Qian YL, Li X. Establishment of a transgenic cell line stably expressing human cytochrome P450 2C18 and identification of a CYP2C18 clone with exon 5 missing. World J Gastroenterol 2002; 8:888-92. [PMID: 12378636 PMCID: PMC4656581 DOI: 10.3748/wjg.v8.i5.888] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/06/2023] Open
Abstract
AIM: The human cytochrome P-450 2C18 (CYP2C18) has been characterized. However, the protein has not been purified from liver and very little is known regarding the specific substrate of CYP2C18. In order to study its enzymatic activity for drug metabolism, the CYP2C18 cDNA was cloned and a stable CHL cell line expressing recombinant CYP 2C18 was established.
METHODS: The human CYP2C18 cDNA was amplified with reverse transcription-polymerase chain reaction (RT-PCR) from total RNAs extracted from human liver and cloned into pGEM-T vector. The cDNA segment was identified by DNA sequencing and subcloned into a mammalian expression vector pREP9. A transgenic cell line was established by transfecting the recombinant plasmid of pREP9-CYP2C18 to Chinese hamster lung (CHL) cell. The enzyme activity of CYP2C18 catalyzing oxidation of tolbutamide to hydroxytolbutamide in postmitochondrial supernant (S9) fraction of the cell was determined by high performance liquid chromatography (HPLC).
RESULTS: The amino acid sequence predicted from the cloned cDNA segment was identical to that of reported by Romkes et al[3] (GenBank accession number: M61856, J05326). The S9 fraction of the established cell line metabolizes tolbutamide to hydroxytolbutamide. Tolbutamide hydroxylase activity was found to be 0.509 ± 0.052 μmol·min-1·g-1 S9 protein or 8.82 ± 0.90 mol·min-1·mol-1 CYP, but was undetectable in parental CHL cell. In addition, we have identified a CYP2C18 cDNA clone with exon 5 missing.
CONCLUSION: The cDNA of human CYP2C18 was successfully cloned and a cell line, CHL-CYP2C18, efficiently expressing the protein of CYP2C18, was established. A spliced variant of CYP2C18 with exon 5 missing was identified in the cloning process.
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Affiliation(s)
- Jian Zhu-Ge
- Department of Pathophysiology and Laboratory of Medical Molecular Biology, Zhejiang University School of Medicine, Hangzhou 310031, Zhejiang Province, China
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Moridani MY, Cheon SS, Khan S, O'Brien PJ. Metabolic activation of 4-hydroxyanisole by isolated rat hepatocytes. Drug Metab Dispos 2002; 30:1063-9. [PMID: 12228181 DOI: 10.1124/dmd.30.10.1063] [Citation(s) in RCA: 23] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022] Open
Abstract
A tyrosinase-directed therapeutic approach for treating malignant melanoma uses depigmenting phenolic prodrugs such as 4-hydroxyanisole (4-HA) for oxidation by melanoma tyrosinase to form cytotoxic o-quinones. However, in a recent clinical trial, both renal and hepatic toxicity were reported as side effects of 4-HA therapy. In the following, 4-HA (200 mg/kg i.p.) administered to mice caused a 7-fold increase in plasma transaminase toxicity, an indication of liver toxicity. Furthermore, 4-HA induced-cytotoxicity toward isolated hepatocytes was preceded by glutathione (GSH) depletion, which was prevented by cytochrome p450 inhibitors that also partly prevented cytotoxicity. The 4-HA metabolite formed by NADPH/microsomes and GSH was identified as a hydroquinone mono-glutathione conjugate. GSH-depleted hepatocytes were much more prone to cytotoxicity induced by 4-HA or its reactive metabolite hydroquinone (HQ). Dicumarol (an NAD(P)H/quinone oxidoreductase inhibitor) also potentiated 4-HA- or HQ-induced toxicity whereas sorbitol, an NADH-generating nutrient, prevented the cytotoxicity. Ethylenediamine (an o-quinone trap) did not prevent 4-HA-induced cytotoxicity, which suggests that the cytotoxicity was not caused by o-quinone as a result of 4-HA ring hydroxylation. Deferoxamine and the antioxidant pyrogallol/4-hydroxy-2,2,6,6-tetramethylpiperidene-1-oxyl (TEMPOL) did not prevent 4-HA-induced cytotoxicity, therefore excluding oxidative stress as a cytotoxic mechanism for 4-HA. A negligible amount of formaldehyde was formed when 4-HA was incubated with rat microsomal/NADPH. These results suggest that the 4-HA cytotoxic mechanism involves alkylation of cellular proteins by 4-HA epoxide or p-quinone rather than involving oxidative stress.
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Affiliation(s)
- M Y Moridani
- Department of Pediatric Laboratory Medicine, Hospital for Sick Children and Faculty of Pharmacy, University of Toronto, Toronto, Ontario, Canada
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Niwa T, Kageyama A, Kishimoto K, Yabusaki Y, Ishibashi F, Katagiri M. Amino acid residues affecting the activities of human cytochrome P450 2C9 and 2C19. Drug Metab Dispos 2002; 30:931-6. [PMID: 12124312 DOI: 10.1124/dmd.30.8.931] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/02/2023] Open
Abstract
The amino acid residues affecting the substrate specificity of human cytochrome P450 CYP2C9 and CYP2C19 for their metabolic activities were investigated using chimeras and mutant enzymes, which were constructed by replacing the corresponding residues. Although CYP2C19 showed nearly the same tolbutamide hydroxylase activity as CYP2C9, the activities for the CYP2C19(H99I) mutant and the chimeras that replaced residues 1-212 were much lower than those for CYP2C19. The activities of the CYP2C19(H99I) mutant and the chimeras that replaced residues 228-340 were lower than those for CYP2C19 toward S-mephenytoin, aminopyrine, and testosterone. These results suggest that residues in substrate recognition site (SRS) 3 and 4 are important for the substrate specificity, whereas His99 is important in the substrate binding of CYP2C19. For the 4'-hydroxylation of diclofenac, CYP2C9 had a lower K(m) and a higher V(max) than CYP2C19. Although the V(max) values for the CYP2C9(1-288)/CYP2C19(289-490) chimera and the CYP2C9(I99H, V292A, F295L, I331V) mutant were comparable to those for CYP2C9, its K(m) value was comparable to that for CYP2C19. The V(max) and K(m) values for the CYP2C19(1-288)/CYP2C9(289-490) chimera were comparable to those for CYP2C19, and the activity by CYP2C9(1-230)/CYP2C19(231-490) chimera was negligible. These results suggest that the residues 292, 295, and/or 331 of CYP2C9 are essential for the recognition of substrate in CYP2C9 and that the residues of 231-288 including SRS 3 are important for the metabolizing capacity of CYP2C9.
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Affiliation(s)
- Toshiro Niwa
- Division of Natural Science, Osaka Kyoiku University, Kashiwara, Osaka, Japan
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Grand F, Kilinc I, Sarkis A, Guitton J. Application of isotopic ratio mass spectrometry for the in vitro determination of demethylation activity in human liver microsomes using N-methyl-13C-labeled substrates. Anal Biochem 2002; 306:181-7. [PMID: 12123654 DOI: 10.1006/abio.2002.5701] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
The reaction of demethylation mediated by cytochrome P450 (CYP) leads to the equimolar production of demethylated metabolite and formaldehyde. From a 13C-substrate labeled on a carbon of the methyl moiety, [13C]formaldehyde (H13CHO) is liberated. A highly sensitive and specific assay involving the oxidation of H13CHO to 13CO(2) by a double-enzymatic-step reaction is reported. The 13CO(2) was quantified by the method of reverse isotopic dilution based on gas chromatography-isotope ratio mass spectrometry analysis. The method first involves the limiting step of the CYP-dependent reaction, which is stopped with a mixture of zinc sulfate 5 mM and trichloroacetic acid 100 mM. Then, the transformation of H13CHO to 13CO(2) is performed with the formaldehyde (0.2 unit) and the formate (0.2 unit) dehydrogenase NAD-dependent enzymes. The recovery of 13CO(2) from the incubation mixture was equal to 91.4 +/- 3.0%. The accuracy and the precision of the present method were within 12 and 10%, respectively. The limit of quantification was set to 25 pmol. The performance of the assay was validated on human liver microsomes with five probes: [13C]erythromycin, [1-13C]caffeine, [3-13C]caffeine, [7-13C]caffeine, and [13C(2)]aminopyrine. This method is useful for the rapid determination of N-demethylase activity of human liver microsomes from methyl-13C-substrates.
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Affiliation(s)
- Florence Grand
- Fédération de Biochimie, Laboratoire de Biochimie C, Hôpital E. Herriot, 69437 Lyon Cedex 03, France
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Niwa T, Maekawa Y, Fujimoto M, Kishimoto K, Yabusaki Y, Ishibashi F, Katagiri M. Inhibition of human hepatic cytochrome P450s and steroidogenic CYP17 by nonylphenol. Biol Pharm Bull 2002; 25:235-8. [PMID: 11853173 DOI: 10.1248/bpb.25.235] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Effect of nonylphenol on aminopyrine N-demethylase activity, a typical drug-metabolizing enzyme activity, by ten kinds of human hepatic cytochrome P450s (CYP) and on progesterone 17alpha-hydroxylase activity by steroidogenic CYP17 was investigated. When determined at 2 mM substrate concentration, nonylphenol (1 mM) most efficiently inhibited aminopyrine N-demethylation by CYP2C9 and CYP2C19, by 61% and 59%, respectively, followed by CYP2D6, CYP1A2, CYP2C18 and CYP2C8 (46-51%), whereas inhibition of the activities by other CYPs was less than 27%. Additionally, nonylphenol competitively inhibited diclofenac 4'-hydroxylation by CYP2C9 and S-mephenytoin 4'-hydroxylation by CYP2C19 with Ki values of 5.3 and 37 microM, respectively. Furthermore, nonylphenol exhibited a competitive inhibition of progesterone 17alpha-hydroxylase activity by CYP17 with Ki value of 62 microM. These results suggest that nonylphenol inhibits human hepatic CYPs, especially CYP2C9 and CYP2C19, and steroidogenic CYP17 activities.
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Affiliation(s)
- Toshiro Niwa
- Division of Natural Science, Osaka Kyoiku University, Kashiwara, Japan
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Abstract
This chapter is an update of the data on substrates, reactions, inducers, and inhibitors of human CYP enzymes published previously by Rendic and DiCarlo (1), now covering selection of the literature through 2001 in the reference section. The data are presented in a tabular form (Table 1) to provide a framework for predicting and interpreting the new P450 metabolic data. The data are formatted in an Excel format as most suitable for off-line searching and management of the Web-database. The data are presented as stated by the author(s) and in the case when several references are cited the data are presented according to the latest published information. The searchable database is available either as an Excel file (for information contact the author), or as a Web-searchable database (Human P450 Metabolism Database, www.gentest.com) enabling the readers easy and quick approach to the latest updates on human CYP metabolic reactions.
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Affiliation(s)
- Slobodan Rendic
- Faculty of Pharmacy and Biochemistry, University of Zagreb, Croatia.
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Achilefu S, Dorshow RB. Dynamic and Continuous Monitoring of Renal and Hepatic Functions with Exogenous Markers. Top Curr Chem (Cham) 2002. [DOI: 10.1007/3-540-46009-8_2] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
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Niwa T, Fujimoto M, Kishimoto K, Yabusaki Y, Ishibashi F, Katagiri M. Metabolism and interaction of bisphenol A in human hepatic cytochrome P450 and steroidogenic CYP17. Biol Pharm Bull 2001; 24:1064-7. [PMID: 11558570 DOI: 10.1248/bpb.24.1064] [Citation(s) in RCA: 44] [Impact Index Per Article: 1.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
The metabolism of bisphenol A (BPA) was determined for 11 forms of human hepatic cytochromes P450 (CYPs) expressed in the yeast Saccharomyces cerevisiae and for human steroidogenic CYP17 expressed in Escherichia coli. Additionally, the effect of BPA on the progesterone 17alpha-chydroxylase activity of CYP17 was investigated. CYP2C18 catalyzed BPA metabolism most efficiently, followed by CYP2C19 and CYP2C9. CYP2C9 and CYP2C18 exhibited the highest affinity (Km=3.9 microM) for BPA metabolism. The Vmax of CYP2C18 (8.10 nmol x min(-1) x nmol CYP(-1)) was 5 times higher than that of CYP2C9. Although the Vmax of CYP2C19 was 1.5 times higher than that of CYP2C18, the affinity of CYP2C19 was 12 times lower than that of CYP2C9 and CYP2C18. Therefore the intrinsic clearance (Vmax/Km) of CYP2C18 was more than 5 times higher than that of CYP2C9 and CYP2C19. On the other hand, BPA exhibited a competitive-type inhibition of the progesterone 17alpha-hydroxylase activity of CYP17 with a Ki value of 71 microM, whereas no metabolism of BPA by CYP17 was detected. These results suggest that BPA is mainly metabolized by the CYP2C subfamily in human liver, and that BPA inhibits human steroidogenic CYP17 activities.
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Affiliation(s)
- T Niwa
- Division of Natural Science, Osaka Kyoiku University, Kashiwara, Japan
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