摘要
目的体外代谢研究槲皮素对大鼠肝CYP1A2,CYP2E1,和CYP3A2活性的影响。研究其抑制强度及抑制机制。方法QU与底物共同温孵,HPLC检测底物特定的代谢产物生成量的变化反映对应亚酶的活性变化。比较槲皮素与酮康唑,红霉素在相同浓度下对CYP3A2的抑制能力强弱。不同浓度槲皮素对CYP3A2和CYP2E1底物代谢产物生成双倒数直线的影响初步分析槲皮素可能的抑制机制。结果各HPLC检测方法线性相关系数均>0.9991,RSD均<8.4%,回收率91.1%-107.6%。槲皮素在体外0～8μmol·L-1诱导大鼠肝微粒体CYP1A2的活性达338.1%,并抑制CYP2E1(49.2%),和CYP3A2(60.3%)。槲皮素对CYP3A2的抑制能力在酮康唑和红霉素之间。槲皮素竞争性抑制CYP3A2右美沙芬N脱甲基反应,非竞争性抑制CYP2E1氯唑沙宗6羟化反应。结论槲皮素对多个CYP450亚酶有抑制作用,它是有效的CYP3A竞争性抑制剂。做为黄酮类植物雌激素,槲皮素有分子结构的优势亦有对CYP450酶调控能力而具有未来抗肿瘤药物研究的潜力。
Aim To assess the potential effect of quercetin （QU）, an natural plant estrogen, on CYP1A2, CYP2E1, and CYP3A2 activities in rat liver microsomes; and to identify the magnitude of inhibitory effect and the probable inhibitory mechanism of QU. Methods QU and specific substrate were concurrently incubated, with HPLC detection of the substrate metabolites for data analysis. The magnitude of inhibitory effect of QU on CYP3A2 was compared with those of ketoconazole （Ket） and erythromycin （Ery）. The mechanism of its inhibitory effect on CYP3A2 and CYP2E1 was derived from Lineweaver-Burk plots. Results HPLC methods were in good linear relationship with r〉0.999 1. Relative standard deviations for intra-day and inter-day were〈8.4%. Recovery of each analyte in the concentrations studied was between 91.1% and 107.6 %. QU （up to 8 μmol·L^-1） showed potent induction to CYP1A2 （338.1% of the negative control）while inhibited CYP2E1 （49.2% of the negative control） and CYP3A2 （60.3% of the negative control） activity. The magnitude of inhibitory effect for QU on CYP3A2 was between those for Ket and Ery （Ket〉QU〉Ery）. QU exhibited competitive inhibition of CYP3A2 dextromethorphan N-demethylation reaction and expressed noncompetitive inhibition of CYP2E1 chlorzoxazone-6-hydroxylation reaction. Conclusion HPLC assay has been validated with precision and accuracy. QU is an effective inhibitor of several CYP isoforms. It may cause relevant drug-drug interactions with CYP3A substrates. As a plant flavonoid, QU has potential not only in molecular advantage but also in CYP450 module capability for further application in cancer chemotherapy.
