大黄素的Ⅰ相代谢途径及其对细胞色素P450酶的抑制作用

Investigation on P450s involved in emodin`s phaseⅠmetabolism and inhibitory effect of emodin on P450s

目的:考察大黄素的I相代谢途径及其对细胞色素P450酶的影响,为预测临床上可能的大黄素-药物相互作用提供实验依据。方法:分别应用人肝微粒体和重组CYP3A4酶与大黄素及CYP3A4抑制剂酮康唑(KTZ)共孵育20min,LC-MS/MS检测分析大黄素原型药物含量的变化;体外Cocktail法评价大黄素对8种P450亚型酶的抑制作用。结果:大黄素与人肝微粒体或重组CYP3A4酶共孵育后,大黄素剩余量分别为68.5%和0.015%,加入100μmol/L的KTZ后,消除率分别降至0.1%和27.7%。体外肝微粒体cocktail实验结果表明,大黄素对大鼠肝微粒体中CYP1A2、CYP2C9、CYP2D6有中等强度抑制作用,IC50分别为3.31、2.60和2.56μmol/L。结论:大黄素I相代谢主要由CYP3A4介导,对多种P450酶具有抑制作用,临床使用含大黄素相关制剂应注意可能涉及的药物相互作用。

AIM：To identify the P450sinvolved in emodins phaseⅠmetabolism and inhibitory effect of emodin on the P450s,in order to provide experimental evidence for predicting possible emodin-drug interactions.METHODS：Human liver microsome and recombinant P450enzymes were incubated with emodin and CYP3A4 inhibitor ketoconazole（KTZ）for 20 mins in vitro,emodin concentrations were determined by LC-MS/MS method.Inhibitory effects of emodin on the P450enzyme isoforms were investigated using an established in vitro cocktail incubation approach in our lab.RESULTS：Co-incubation with human liver microsomes and recombinant CYP3A4 system in vitro showed that emodin remains 68.5%and 0.015%of the initial content,100μmol/L KTZ could decrease the elimination rate to 0.1% and 27.7%respectively.The results from the cocktail experiment indicated that emodin had a moderate inhibition on CYP1A2,CYP2C9,CYP2D6with IC50as 3.31,2.60,2.56μmol/L respectively.CONCLUSION：CYP3A4plays a key role for emodin biotransformation in phaseⅠmetabolism,possessing the inhibitory effect on multiple P450s.Attention should be paid to avoid the possible emodin-drug interaction when emodin-containing preparations are prescribed with substrates of these mentioned P450s.