基于代谢酶考察何首乌与制何首乌肝毒性差异

Study on the difference of hepatotoxicity between Polygonum multiflorum and Polygonum multiflorum praeparata based on metabolic enzyme

目的:以胆红素代谢过程中UDP-葡萄糖醛酸转移酶1A1(UGT1A1酶)介导的胆红素葡萄糖醛酸结合环节为切入点,考察何首乌与制何首乌的潜在肝毒性,以及二者毒性差异。方法:以胆红素为UGT1A1酶底物,以表观抑制常数Ki为评价指标,采用体外肝微粒体孵育法,启动Ⅱ相代谢反应,考察何首乌与制何首乌中原形成分的抑制作用,启动Ⅰ相代谢反应,考察代谢产物及原形成分的抑制作用。结果:何首乌与制何首乌以原形形式直接作用于UGT1A1酶后,制何首乌为中等抑制,何首乌为强抑制作用,抑制类型均为竞争型抑制;何首乌与制何首乌经过Ⅰ相代谢后,何首乌抑制作用减弱,同时抑制类型变为混合型抑制,制何首乌抑制作用消失。提示何首乌与制何首乌的差异成分具有更强的潜在毒性,共有成分经过Ⅰ相代谢后抑制作用减弱。结论:本研究初步证明何首乌与制何首乌中原形成分对UGT1A1存在抑制作用,经由Ⅰ相代谢后,抑制作用降低或消失。与何首乌相比,制何首乌肝毒性风险较小。

Objective:To study the hepatotoxicity of Polygonum multiflorum(Polygonum multiflorum)and Polygonum multiflorum praeparata on the basic of the bilirubin metabolism mediated by glucuronidation of UDP-glucuronosyltransferases 1 A1(UGT1 A1 enzyme),thus to clarify the toxicity difference between the two medicines.Methods:The extracts were added into the rat liver microsomes to test the hepatotoxicity,using bilirubin as UGT1 A1 enzyme substrate to investigate the inhibition of the UGT1 A1 enzyme.In vitro microsome incubation system the apparent inhibition constant Ki was used to evaluate the hepatotoxicity.PhaseⅠmetabolic reaction was initiated to investigate the inhibition of metabolites and prototype components,and speculate the potential toxic effects of the analytes.Results:When Polygonum multiflorum and Polygonum multiflorum praeparata were directly applied to the UGT1 A1 enzyme in the form of a prototype,Polygonum multiflorum praeparata showed moderate inhibition,Polygonum multiflorum demonstrated strongly inhibitory effect,and both inhibition types were competitive inhibition.After the phase I metabolism the inhibitory effect of Polygonum multiflorum was weakened.The type of inhibition changed to mixed inhibition,and the inhibition effect of Polygonum multiflorum praeparata disappeared.It was suggested that the different components of Polygonum multiflorum and Polygonum multiflorum praeparata hadstronger potential toxicity,and the inhibitory effect of the common components were weakened after phase I metabolism.Conclusion:This experiment preliminarily proved that the prototype components of Polygonum multiflorum and Polygonum multiflorum praeparata have inhibition effect on UGT1 A1,and the inhibition decreases or disappears after phase I metabolism.Compared with Polygonum multiflorum,the risk of liver toxicity of Polygonum multiflorum praeparata is small.