title: Identification of human cytochrome P450 isoforms involved in the metabolism of S-2-[4-(3-methyl-2-thienyl)phenyl]propionic acid.
abstract: 1. To identify the cytochrome P450 (CYP) isoenzymes responsible for the major metabolic pathways of S-2-[4-(3-methyl-2-thienyl)phenyl] propionic acid (S-MTPPA) in man, the metabolism of S-MTPPA was examined using human liver microsomes and microsomes containing cDNA-expressed CYP isozymes (CYP1A2, 2A6, 2B6, 2C9-Arg, 2C9-Cys, 2C19, 2D6-Val, 2E1 and 3A4). 2. S-MTPPA was mainly oxidized to the 5-hydroxylated metabolite of the thiophene ring (MA6) with human liver microsomes in the presence of NADPH. The formation of MA6 was inhibited by SKF 525-A, suggesting that CYP plays role in the formation of MA6. 3. Eadie-Hofstee plots for the 5-hydroxylation of S-MTPPA in the range 5-100 microM were linear for all samples studied, suggesting that the formation of MA6 by human liver microsomes follows simple Michaelis-Menten kinetics. Apparent Vmax = 1.42+/-0.64 nmol/min/mg protein; Km = 12+/-5 microM. 4. Among the CYP inhibitors examined (alpha-naphthoflavone, sulphaphenazole, omeprazole, quinidine and troleandomycin), sulphaphenazole (a CYP2C9 inhibitor) showed the most potent inhibitory effect on the 5-hydroxylation of S-MTPPA by human liver microsomes. 5. When incubated with microsomes containing cDNA-expressed CYP isozymes, S-MTPPA was substantially oxidized to MA6 only by CYP2C9. 6. These results suggest that formation of the major metabolite of S-MTPPA, MA6, in human liver microsomes is catalysed predominantly by a single CYP isoenzyme, namely CYP2C9.
authors.affiliation: Pharmacokinetic Research Section, Research and Development Laboratories, Maruho Co., Ltd, Kyoto, Japan.
authors.forename: K
authors.initials: K
authors.lastname: Taguchi
authors.forename: T
authors.initials: T
authors.lastname: Konishi
authors.forename: H
authors.initials: H
authors.lastname: Nishikawa
authors.forename: S
authors.initials: S
authors.lastname: Kitamura
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000378:metabolism*; D001189:Aryl Hydrocarbon Hydroxylases; D001571:Benzoflavones / Q000494:pharmacology; D019388:Cytochrome P-450 CYP1A2; D065729:Cytochrome P-450 CYP2C9; D019392:Cytochrome P-450 CYP2E1 / Q000235:genetics / Q000378:metabolism; D051544:Cytochrome P-450 CYP3A; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000235:genetics / Q000378:metabolism*; D004338:Drug Combinations; D004365:Drugs, Chinese Herbal / Q000494:pharmacology; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006035:Glycyrrhiza; D006801:Humans; D007527:Isoenzymes; D007700:Kinetics; D008862:Microsomes, Liver / Q000187:drug effects / Q000378:metabolism*; D006899:Mixed Function Oxygenases / Q000235:genetics / Q000378:metabolism; D009853:Omeprazole / Q000494:pharmacology; D029596:Paeonia; D010666:Phenylpropionates / Q000378:metabolism*; D011802:Quinidine / Q000494:pharmacology; D011994:Recombinant Proteins / Q000187:drug effects / Q000235:genetics / Q000378:metabolism; D039181:Steroid 16-alpha-Hydroxylase; D013250:Steroid Hydroxylases / Q000235:genetics / Q000378:metabolism; D013426:Sulfaphenazole / Q000494:pharmacology; D014217:Troleandomycin / Q000494:pharmacology
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D001571:Benzoflavones; D065607:Cytochrome P-450 Enzyme Inhibitors; D004338:Drug Combinations; D004365:Drugs, Chinese Herbal; D004791:Enzyme Inhibitors; D007527:Isoenzymes; D010666:Phenylpropionates; D011994:Recombinant Proteins; C038462:shakuyaku-kanzoh-toh; D013426:Sulfaphenazole; C011512:alpha-naphthoflavone; C104139:2-(4-(3-methyl-2-thienyl)phenyl)propionic acid; D003577:Cytochrome P-450 Enzyme System; D014217:Troleandomycin; D006899:Mixed Function Oxygenases; D013250:Steroid Hydroxylases; C450260:CYP2C9 protein, human; D065729:Cytochrome P-450 CYP2C9; D019392:Cytochrome P-450 CYP2E1; D001189:Aryl Hydrocarbon Hydroxylases; C504573:CYP1A2 protein, human; C104464:CYP3A protein, human; D019388:Cytochrome P-450 CYP1A2; D051544:Cytochrome P-450 CYP3A; D039181:Steroid 16-alpha-Hydroxylase; D011802:Quinidine; D009853:Omeprazole