To investigate the metabolic stability of E7 in liver microsomes of human, Beagle dog, Cynomolgus monkey and SD rats, and compare the metabolic differences between different species. Selective chemical inhibitors were used to determine the effects of different inhibitors on E7 metabolic rate, and predict the main enzymes involved in E7 metabolism in rat liver microsomes. The experimental results showed that the in vitro half-lives (T1/2) of E7 in liver microsomes of human, dog, monkey and rats were 57.75, 69.30, 16.90,30.13 min respectively. Their intrinsic clearance rate was 0.004 8, 0.004 0, 0.016 4 and 0.009 2 mL•min⁻¹•mg⁻¹ respectively. Hence, it could be speculated that the metabolic rate of E7 was similarly slow in human and dog liver microsomes; while it was similarly fast in monkey and rat liver microsomes. There was significant difference in metabolic rate of E7 between different species. The results showed that CYP2E1, CYP2A6, CYP1A2 and CYP2D6 might participate in metabolism of E7, while the contribution of polymorphic CYP3A4 was small.
Keywords: E7; liver microsomes; metabolic phenotype; metabolic stability.
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