雷公藤甲素体外对大鼠CYP450酶活性的影响及其与甘草次酸的代谢相互作用

Inhibitory effects of triptolide on rat CYP450 enzymes and the metabolic interaction with glycyrrhetinic acid in vitro

目的:研究雷公藤甲素(TP)对大鼠肝微粒体(RLM)中主要CYP450酶活性的影响及其与甘草次酸(GA)的代谢相互作用。方法:TP分别与CYP1A2、CYP2E1、CYP2C和CYP3A的探针底物在RLM中共温孵反应,检测探针底物代谢物的生成速率,计算TP对各酶活性的IC50值。GA与TP在RLM中共温孵反应,检测TP羟基化代谢物的生成量,计算GA对TP体外代谢的IC50与Ki值。结果:TP对CYP2C、CYP3A、CYP1A2和CYP2E1的IC50值分别为>50、>50、43μmol/L和14μmol/L。GA对TP体外代谢抑制的Ki值为43.9μmol/L,对其4种代谢物(M1、M2、M3和M4)生成的IC50值分别为24.6、23.5、19.6、22.4μmol/L。且GA代谢物对TP的体外代谢具有更强的抑制作用。结论:TP对CYP2C和CYP3A活性无显著影响,对CYP1A2活性有一定抑制作用,对CYP2E1活性有较强抑制作用。GA及其代谢物能竞争性抑制TP的体外代谢。

Objective： To investigate the effects of triptolide （TP） combined on the activity of CYP450 enzymes in rat liver microsome （RLM） and the metabolic interaction with glycyrrhetinic acid （GA） in vitro. Methods： After the co-incubation of TP with the probe substrates of CYP1A2, 2E1, 2C and 3A in RLM respectively, the formation rates of the metabolites of probe substrates, as well as and the IC50 values of TP on CYP450 enzymes, were determined. In the same way, the Ki and IC50 values of GA on TP metabolism were also determined. Results： The IC50 values of TP on CYP2C, CYP3A, CYP1A2 and CYP2E1 were 〉50, 〉50, 43 and 14 pmol/L respectively. The Ki value of GA on TP metabolism was 43.9μmol/L, and IC50 values of GA on the formation of TP metabolites： M1, M2, M3 and M4, were 24.6, 23.5, 19.6 and 22.4prnol/L respectively. Furthermore, GA metabolites had more powerful inhibitory potency than GA. Conclusion： TP had a significantly inhibitory action on CYP2E1, slightly inhibitory action on CYP2C, no significant effect on CYP3A and CYP1A2 in vitro. GA and its metabolites competitively inhibited the in vitro metabolism of TP.