Human liver cytochrome P450 enzymes involved in the 7-hydroxylation of R- and S-warfarin enantiomers
Human liver cytochrome P450 enzymes involved in the 7-hydroxylation of R- and S-warfarin enantiomers
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DOI：
10.1016/s0006-2952(97)00304-3
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发表时间：
1997-12-01
影响因子：
5.8
通讯作者：
Shimada, T
中科院分区：
文献类型：
--
作者：
Yamazaki, H;Shimada, T
人肝微粒体中s -华法林的7-羟基化活性比r -华法林高8倍。35份人肝微粒体外消旋华法林7-羟基化活性与s -华法林7-羟基化活性的相关性（r = 0.95）大于与r -华法林7-羟基化活性的相关性（r = 0.69）。在这些人体样品中，r -华法林7-羟基化活性和7-乙氧基间苯甲酚o -去甲基化活性的相关系数为0.73，表明r -华法林和s -华法林对映体是由不同形式的人类细胞色素P450 （P450或CYP）酶催化的。抗cyp2c9抗体能完全抑制s -华法林的7-羟基化，但不能抑制人肝微粒体催化的r -华法林7-羟基化，而抗cyp1a2抗体能抑制r -华法林7-羟基化约70%。有趣的是，外消旋华法林7-羟基化活性（35个人体样品中1.6 +/- 1.0 pmol/min/mg蛋白的周转率）比s -华法林7-羟基化活性（4.1 +/- 2.5 pmol/min/mg蛋白）低，表明当外消旋华法林作为底物时，r -华法林可能影响了cyp2c9依赖性s -华法林7-羟基化活性。研究了几种P450抑制剂以及r -华法林抑制s -华法林7-羟基化的能力；我们发现r -华法林是一种非竞争性抑制剂，K-i值约为150 μ M，而甲苯丁酰胺和磺胺苯唑是s -华法林7-羟基化活性的竞争性抑制剂，K-i值分别约为100 μ M和0.5 μ M。这些结果表明，R-华法林和s -华法林对映体在人肝微粒体中分别主要由CYP1A2和CYP2C9催化，当临床给药时，s -华法林在体内可能被R-华法林改变药代动力学特性。(C) 1997爱思唯尔科学有限公司
Human liver microsomes had about 8-fold higher 7-hydroxylation activities for S-warfarin than for R-warfarin. Activities of racemic warfarin 7-hydroxylation by liver microsomes of 35 human samples correlated more closely with those of S-warfarin 7-hydroxylation (r = 0.95) than with those of R-warfarin 7-hydroxylation (r = 0.69). The correlation coefficient between R-warfarin 7-hydroxylation and 7-ethoxyresorufin O-deethylation activities was 0.73 in these human samples, suggesting that R-and S-warfarin enantiomers are catalyzed by different forms of human cytochrome P450 (P450 or CYP) enzymes. Anti-CYP2C9 antibodies inhibited completely the 7-hydroxylation of S-warfarin, but not R-warfarin, catalyzed by human liver microsomes, while anti-CYP1A2 inhibited R-warfarin 7-hydroxylation by about 70%. Interestingly, the racemic warfarin 7-hydroxylation activities (turnover numbers of 1.6 +/- 1.0 pmol/min/mg protein in 35 human samples) were found to be low compared with the S-warfarin 7-hydroxylation activities (4.1 +/- 2.5 pmol/min/mg protein), indicating that R-warfarin may have affected the CYP2C9-dependent S-warfarin 7-hydroxylation activities when racemic warfarin was used as a substrate. Several P450 inhibitors, as well as R-warfarin, were examined for their abilities to inhibit S-warfarin 7-hydroxylation; we found that R-warfarin was a non competitive inhibitor with a K-i value of about 150 mu M, whereas both tolbutamide and sulfaphenazole were competitive inhibitors with K-i values of about 100 and 0.5 mu M, respectively, for S-warfarin 7-hydroxylation activities. These results suggest that R- and S-warfarin enantiomers are catalyzed principally by CYP1A2 and CYP2C9, respectively, in human liver microsomes, and that the pharmacokinetic properties of S-warfarin may be altered by R-warfarin in vivo when racemic warfarin is administered clinically to humans. (C) 1997 Elsevier Science Inc.