雌二醇在人、比格犬和大鼠的肝微粒体中体外代谢比较研究

采用体外肝微粒体孵育体系, 研究雌二醇在大鼠、比格犬和人肝微粒体中酶代谢动力学及代谢产物差异。通过对雌二醇浓度、肝微粒体蛋白含量和孵育时间等条件的考察, 优化雌二醇与肝微粒体的反应体系; 应用LC-MS/MS定量检测孵育体系中的雌二醇及代谢产物, 分析比较雌二醇在3个种属、不同性别肝微粒体中代谢产物种类和生成量的差异, 计算并比较相应的动力学参数。在3个种属肝微粒体中均发现9个I相代谢产物, 且百分比有种属差异。结果表明, 3个种属的肝微粒体对雌二醇I相代谢途径基本相同, 但是代谢产物的生成量及雌二醇的药物代谢动力学性质存在一定的差异。

In vivo comparison of estradiol metabolism in liver microsomes of human, Beagle dog and rat

The inter-species differences of estradiol metabolism were investigated in human, Beagle dog and rat liver microsomes by comparing enzyme kinetics of parent drug and the formation of its major metabolites.  The incubation systems of estradiol with liver microsomes of the three species were optimized in terms of estradiol concentration, microsomal protein content and incubation time.  The concentrations of estradiol and its metabolites were measured by LC-MS/MS method.  The t_1/2, CL_int, CL_h, K_m and V_max of estradiol incubated with male human liver microsomes were 40.02 ± 8.32 min, 41.39 ± 6.57 mL·min⁻¹·kg⁻¹, 13.81 ± 12.36 mL·min⁻¹·kg⁻¹, 26.8 ± 6.99 μmol·L⁻¹ and 0.75 ± 0.92 μmol·L⁻¹·min⁻¹, respectively.  The corresponding parameters of female human were 44.71 ± 10.21 min, 29.85 ± 8.97 mL·min⁻¹·kg⁻¹, 0.01 ± 0.68 mL·min⁻¹·kg⁻¹, 44.2 ± 7.73 μmol·L⁻¹ and 1.27 ± 4.41 μmol·L⁻¹·min⁻¹, that of male dog were 21 ± 7.33 min, 165.53 ± 29.33 mL·min⁻¹·kg⁻¹, 26.01 ± 8.39 mL·min⁻¹·kg⁻¹, 19.5 ± 7.34 μmol·L⁻¹ and 1.6 ± 0.65 μmol·L⁻¹·min⁻¹, that of female dog were 25.5 ± 5.32 min, 135.11 ± 42.34 mL·min⁻¹·kg⁻¹, 0.24 ± 3.18 mL·min⁻¹·kg⁻¹, 8.33 ± 6.32 μmol·L⁻¹ and 0.51 ± 2.15 μmol·L⁻¹·min⁻¹, that of male rat were 5.11 ± 3.84 min, 485.63 ± 36.52 mL·min⁻¹·kg⁻¹, 49.57 ± 15.29 mL·min⁻¹·kg⁻¹, 62 ± 13.74 μmol·L⁻¹ and 19.16 ± 9.67 μmol·L⁻¹·min⁻¹, and that of female rat were 7.0 ± 3.69 min, 354.82 ± 33.33 mL·min⁻¹·kg⁻¹, 8.04 ± 3.23 mL·min⁻¹·kg⁻¹, 35.38 ± 7.65 μmol·L⁻¹ and 8.39 ± 4.91 μmol·L⁻¹·min⁻¹, respectively.  There were nine metabolites detected from all the three species, but the relative amounts of the metabolites generated were different in three species.  The results indicted that the major phase I metabolic pathway of estradiol was similar in the liver microsomes from all the three species.  However, the inter-species differences were found in the view of relative amounts of the metabolites as well as the metabolic characteristics of estradiol in liver microsomal incubation.