title: Characterization of the cytochrome P450 enzymes involved in the metabolism of a new cardioprotective agent KR-33028.
abstract: KR-33028 (N-[4-cyano-benzo[b]thiophene-2-carbonyl]guanidine) is a new cardioprotective agent for preventing ischemia-reperfusion injury. This study was performed to characterize the cytochrome P450 (CYP) enzymes that are involved in the metabolism of KR-33028. Hydroxylation (5-hydroxy- and 7-hydroxy-KR-33028) is major pathways for the metabolism of KR-33028 in human liver microsomes. Among the nine c-DNA expressed CYP isoforms tested, KR-33028 was 5-hydroxylated by CYP3A4 and 7-hydroxylated by CYP1A2, CYP3A4, and CYP2C19. These findings were supported by the combination of chemical inhibition studies in human liver microsomes and correlation analysis. Furafylline and ketoconazole potently inhibited hydroxylation of KR-33028 in human liver microsomes. Correlation analysis between the known CYP enzyme activities and the rates of the formation of 5-hydroxy- and 7-hydroxy-KR-33028 in the 16 human liver microsomes has showed significant correlations with CYP3A4-mediated midazolam 1'-hydroxylation and CYP1A2-mediated phenacetin O-deethylation, respectively. A 7-hydroxy-KR-33028 formation is also weakly correlated with CYP3A4-mediated midazolam 1'-hydroxylation. The kinetics of the major biotransformation of KR-33028 were studied: CYP3A4 mediated the formation of 5-hydroxy-KR-33028 from KR-33028 with Cl(int)=0.22microl/min/pmol CYP. The intrinsic clearance for 7-hydroxy-KR-33028 formation by CYP1A2, CYP2C19, and CYP3A4 were 0.26, 0.19, and 0.03microl/min/pmol CYP, respectively. Taken together, these results provide evidence that CYP3A4 and CYP1A2 are the major isoforms responsible for the hydroxy metabolites formation from KR-33028.
authors.affiliation: Department of Pharmacology and PharmacoGenomics Research Center, Inje University College of Medicine, # 633-165, Gaegum-Dong, Busanjin-Gu, Busan 614-735, South Korea.
authors.forename: Hyojin
authors.initials: H
authors.lastname: Kim
authors.forename: Yune-Jung
authors.initials: YJ
authors.lastname: Yoon
authors.forename: Hyunmi
authors.initials: H
authors.lastname: Kim
authors.forename: Suil
authors.initials: S
authors.lastname: Kang
authors.forename: Hyae Gyeong
authors.initials: HG
authors.lastname: Cheon
authors.forename: Sung-Eun
authors.initials: SE
authors.lastname: Yoo
authors.forename: Jae-Gook
authors.initials: JG
authors.lastname: Shin
authors.forename: Kwang-Hyeon
authors.initials: KH
authors.lastname: Liu
mesh_terms: D001711:Biotransformation; D002316:Cardiotonic Agents / Q000493:pharmacokinetics* / Q000494:pharmacology; D002853:Chromatography, Liquid; D065607:Cytochrome P-450 Enzyme Inhibitors; D003577:Cytochrome P-450 Enzyme System / Q000096:biosynthesis*; D004790:Enzyme Induction; D004791:Enzyme Inhibitors / Q000494:pharmacology; D006146:Guanidines / Q000493:pharmacokinetics* / Q000494:pharmacology; D006801:Humans; D006900:Hydroxylation; D066298:In Vitro Techniques; D013058:Mass Spectrometry; D008862:Microsomes, Liver / Q000187:drug effects* / Q000201:enzymology; D013876:Thiophenes / Q000493:pharmacokinetics* / Q000494:pharmacology
chemical_list: D002316:Cardiotonic Agents; D065607:Cytochrome P-450 Enzyme Inhibitors; D004791:Enzyme Inhibitors; D006146:Guanidines; C507425:N-(4-cyano-benzo(b)thiophene-2-carbonyl)guanidine; D013876:Thiophenes; D003577:Cytochrome P-450 Enzyme System