何首乌中8种成分在大鼠肝微粒体体系中的肝毒性研究

Hepatotoxicity of Eight Components of Radix Polygonum multiflorum Thunb. in Rat Liver Microsome System in Vitro

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,考察何首乌中8种单体成分肝毒性。方法以胆红素为UGT1A1酶底物,以表观抑制常数Ki为评价指标,采用体外大鼠肝微粒体孵育法测定待测单体成分肝毒性有无及大小,并寻找构效关系。结果 8种待测单体成分在大鼠肝微粒体(RLM)体系中对UGT1A1酶的抑制情况分别为:大黄素-8-O-葡萄糖苷(中等强度抑制)>大黄素(中等强度抑制)>羟基大黄素(中等强度抑制)>儿茶素(弱抑制)>没食子酸(无抑制)>大黄素甲醚(无抑制)>大黄酸(无抑制)>大黄素-6-O-葡萄糖苷(无抑制)。且存在构效关系,推测6位羟基为活性必需基团。结论本实验所建立的体外研究方法稳定可行。实验结果证明,酶抑制作用存在一定的结构选择性。

OBJECTIVE To investigate the hepatic toxicity of 8 monomers in Polygonum multiflorum using a combination of UDP-glucuronic acid transferase 1A1（UGT1A1 enzyme）.METHODS Bilirubin was used as the substrate for UGT1A1.Incubation method in RLM in vitro was adopted to test the apparent inhibition constants（Ki）of different components.Furthermore the structure-activity relationship between the 8 components and UGT1A1 was analyzed.RESULTS The inhibition effects on UGT1A1 enzyme of the 8 components were in the following sequence：emodin-8-O-glc＞emodin＞citreorosein＞（＋）-catechin＞gallic acid＞physcion＞rhein＞emodin-6-O-glc.Moreover,there was a structure-activity relationship,and it was presumed that the 6-position hydroxyl group is an active and necessary group.CONCLUSION The established method in vitro is stable and feasible.Experimental results shows that the enzyme inhibition has structural selectivity,which provides an experimental basis for predicting the enzyme inhibition activity of the analogues of components of Polygonum multiflorum.