title: In vitro metabolism of a new neuroprotective agent, KR-31543 in the human liver microsomes: identification of human cytochrome P450.
abstract: KR-31543, (2S,3R,4S)-6-amino-4-[N-(4-chlorophenyl)-N-(2-methyl-2H-tetrazol-5-ylmethyl)amino]-3,4-dihydro-2-dimethoxymethyl-3-hydroxy-2-methyl-2H-1-benzopyran, is a new neuroprotective agent for preventing ischemia-reperfusion damage. This study was performed to identify the metabolic pathway of KR-31543 in human liver microsomes and to characterize cytochrome P450 (CYP) enzymes that are involved in the metabolism of KR-31543. Human liver microsomal incubation of KR-31543 in the presence of NADPH resulted in the formation of two metabolites, M1 and M2. M1 was identified as N-(4-chlorophenyl)-N-(2-methyl-2H-tetrazol-5-ylmethyl)amine on the basis of LC/MS/MS analysis with a synthesized authentic standard, and M2 was suggested to be hydroxy-KR-31543. Correlation analysis between the known CYP enzyme activities and the rates of the formation of M1 and M2 in the 12 human liver microsomes have showed significant correlations with testosterone 6beta-hydroxylase activity (a marker of CYP3A4). Ketoconazole, a selective inhibitor of CYP3A4, and anti-CYP3A4 monoclonal antibodies potently inhibited both N-hydrolysis and hydroxylation of KR-31543 in human liver microsomes. These results provide evidence that CYP3A4 is the major isozyme responsible for the metabolism of KR-31543 to M1 and M2.
authors.affiliation: Drug Metabolism and Bioanalysis Laboratory College of Pharmacy, Wonkwang University, Iksan 570-749, Korea.
authors.forename: Hye Young
authors.initials: HY
authors.lastname: Ji
authors.forename: Seung-Seok
authors.initials: SS
authors.lastname: Lee
authors.forename: Sung-Eun
authors.initials: SE
authors.lastname: Yoo
authors.forename: Hosoon
authors.initials: H
authors.lastname: Kim
authors.forename: Dong Ha
authors.initials: DH
authors.lastname: Lee
authors.forename: Hong
authors.initials: H
authors.lastname: Lim
authors.forename: Hye Suk
authors.initials: HS
authors.lastname: Lee
mesh_terms: D001578:Benzopyrans / Q000378:metabolism* / Q000493:pharmacokinetics; D001711:Biotransformation; D002851:Chromatography, High Pressure Liquid; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000378:metabolism*; D018076:DNA, Complementary / Q000096:biosynthesis; D004347:Drug Interactions; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006801:Humans; D066298:In Vitro Techniques; D007527:Isoenzymes / Q000378:metabolism; D007700:Kinetics; D013058:Mass Spectrometry; D008862:Microsomes, Liver / Q000201:enzymology / Q000378:metabolism*; D018696:Neuroprotective Agents / Q000378:metabolism* / Q000493:pharmacokinetics; D010084:Oxidation-Reduction; D013056:Spectrophotometry, Ultraviolet; D013777:Tetrazoles / Q000378:metabolism* / Q000493:pharmacokinetics
chemical_list: D001578:Benzopyrans; D065607:Cytochrome P-450 Enzyme Inhibitors; D018076:DNA, Complementary; D004791:Enzyme Inhibitors; D007527:Isoenzymes; C473251:KR-31543; D018696:Neuroprotective Agents; D013777:Tetrazoles; D003577:Cytochrome P-450 Enzyme System