Stereoselective metabolism of propafenone by human liver CYP3A4 expressed in transgenic Chinese hamster CHL cells lines  

普罗帕酮经转人肝CYP3A4基因中国仓鼠CHL细胞代谢的立体选择性(英文)

作　　者：周权[1] 姚彤炜[1] 余应年[2] 曾苏[1] 

机构地区：[1]浙江大学药学院药物分析与药物代谢研究室 [2]浙江大学医学院病理生理教研室,杭州中国310031

出　　处：《Acta Pharmacologica Sinica》2001年第10期944-948,共5页中国药理学报（英文版）

基　　金：Project supported by the National Natural Science Foundation of China(No 39770868 and No 39670801);Zhejiang Natural Science Foundation (No RC97016)

摘　　要：AIM: To investigate the stereoselective metabolism of propafenone ( PPF ) by human liver CYP3A4. METHODS: A chiral and an achiral HPLC were combined to determine the enantiomer of PPF in S9 incubates prepared from transgenic Chinese hamster CHL cells lines expressing CYP3A4. The time-dependent study was performed using individual enantiomer or racemate at low or high substrate concentration. Kinetic parameters were determined employing individual enantio-mers as substrates. Enantiomeric inhibition expriments were performed by using R( - )-PPF as an inhibitor and S( + )-PPF as a substrate. RESULTS: Stereoselec-tivity was found in metabolism of racemic PPF at low substrate concentration (10 mg/L) (S < R), and lost at high substrate concentration (400 mg/L). When an individual enantiomer of high concentration (200 mg/L) was used as substrate, S( + )-PPF was eliminated faster than its isomer (S > R). However, the opposite situation was observed at low concentration (5 mg/L) (S<R). The Vmax of S( + )-PPF was significantly greater than that of R( - )-PPF [(2.66 ±0.32) vs (1.71±0.19) μmol·mg-1·-min-1]. The Km of R( - )-PPF was significantly lower than that of S( + )-PPF [(73 ± 11) vs (185 ± 17) μmol·L-1]. R( - )-PPF inhibited S( + )-isomer with an IC50 value of 125 μmol·L-1. CONCLUSION: It is concluded that stereoselectivity in metabolism of propafenone via CYP3A4 depend onsubstrate concentration. Enantiomer/enantiomer interaction of PPF occured at high concentration of substrate, and resulted in the loss of stereoselectivity. There maybe no enantiomer/enantiomer interaction at low concentration thus keeping the superiority of R ( - )-PPF in metablism.目的:研究普罗帕酮(PPF)经人肝CYP3A4代谢的立体选择性。方法:以转人肝CYP3A4基因中国仓鼠肺细胞CHL的S_9为酶源,考察了PPF消旋体及单个对映体在高、低底物浓度时的经时孵育代谢。对映体抑制试验用于考察对映体之间的相互作用。并进行了单个对映体的酶动力学试验。结果:PPF消旋体高底物浓度(400mg/L)时的代谢无立体选择性,低底物浓度(10mg/L)时R(-)-体代谢快于S(+)-体(R>S);单个对映体孵育时在高底物浓度(200mg/L)时的代谢呈现对S(+)-体的立体选择性(S>R),低底物浓度(5mg/L)时呈现对R(-)-体的立体选择性(R>S)。S(+)-PPF的V_(max)(μmol·mg^(-1)·min^(-1))大于R(-)-体(2.66±0.32 vs 1.71±0.19,P<0.01)。R(-)-PPF的K_m(μmol·L^(-1))小于S(+)-体(73±11 vs 185±17,P<0.001)。R(-)-PPF对S(+)-体有代谢抑制作用(IC_(50)=125μmol·L^(-1))。结论:PPF经人肝CYP3A4的代谢有底物浓度依赖性的立体选择性。高底物浓度时两对映体有相互作用,相互作用的结果导致立体选择性丧失。而低底物浓度时两对映体无相互作用,结果仍表现出R体代谢优先的立体选择性。

关 键 词：PROPAFENONE STEREOISOMERS METABOLISM cytochrome P-450 CYP3A4 

分 类 号：R96[医药卫生—药理学]