柠檬苦素在大鼠肝微粒体中代谢的性别差异

目的：研究柠檬苦素在大鼠肝微粒体中代谢的性别差异以及引起性别差异的可能的CYP450亚型。方法：柠檬苦素与雌雄大鼠肝微粒体共同孵育，抑制实验为在肝微粒体中加入特异性CYP450抑制剂后，再加入柠檬苦素共同孵育，温孵后的样品乙醚提取后进行HPLC分析。结果：柠檬苦素在雌雄大鼠肝微粒体中代谢的表观酶动力学参数分别为：米氏常数K㎡：（12±3）、（16±4）ug／mL，最大反应速度Vmax：（49±6）、（93±14）ng·min^-1·mg^-1。柠檬苦素在雌雄大鼠肝微粒体中孵育30min的代谢率分别为（33．9±4．7）9／6和（53．8±2．8）％，代谢速度分别为（4．46±0．62）和（7．08±0．37）ng·min^-1·mg^-1。CYP3A2特异性抑制剂酮康唑、CYP2C11特异性抑制剂西咪替丁对柠檬苦素的代谢抑制作用明显，CYPlA2特异性抑制剂a-萘黄酮和CYP2D1特异性抑制剂奎尼丁对柠檬苦素的代谢也有不同程度的抑制作用。结论：柠檬苦素在大鼠肝微粒体中代谢存在明显的性别差异，CYP3A2和CYP2C11在雌雄大鼠肝微粒体中的性别差异可能是引起代谢性别差异的主要原因。

Gender difference of limonin metabolism in rat liver microsomes

To study the gender differ ence of limonin metabolism and the effects of se lective CYP450 inhibitors on the metabolism of limonin in rat liver microsomes. METHODS： Li monin was incubated in rat liver microsomes, the enzyme kinetics parameters were studied; the metabolism of gender differences of limonin in male and female rat liver microsomes were compared; four kinds of CYP450 subtype speci ficity inhibitors were incubated with liver micro somes, the metabolic inhibition of inhibitors of limonin were calculated. RESULTS： The optimal incubation time was 30 rain and the optimal en zyme concentration was 2.0 mg/mL. Km of li monin in female and male rat liver microsomes are （12：t：3） and （164±4） /2g/mL and Vmax are （49±6） and （93±14） ng . min-1 .mg-1. The metabolic percentage are （33.9 ± 4.7） % and（53.8 ± 2.8） % and metabolic rate are （4.46 ± 0.62）and （7.08±0.37）ng- min-1. mg-1 re spectively in {amle and male rat liver micro- somes. Inparticularly Ketoconazole （Ket） and Cimetidine （Cime） had significant inhibitory effects on the metabolism of limonin. It was fur ther found that aNaphthoflavone （α-Naph） and Quinidine （Quin） had little effects on the metab olism of limonin. CONCLUSION： The gender difference of limonin metabolism in rat liver mi crosomes has been investigated in this study, and the CYP3A2 and CYP2C11 may be the main reason for the sex difference.