Background and Objectives: SM-1 is a new synthetic small molecular compound with anti-tumor activity. The metabolism of SM-1 is a key parameter that needs to be evaluated to provide further insight into drug safety and efficacy in the early phases of drug development.

Methods: In this study, the biotransformation process of SM-1, including the metabolic pathways and major metabolites, was investigated based on a liquid chromatography-mass spectrometry method. Upon incubation of SM-1 with human liver microsomes, five metabolites were identified, namely dihydrodiol formation (R1), hydroxylation (R2, R3, and R5), and debenzylation (R4) of SM-1, with R1 and R4 being the major metabolites. The enzyme kinetic parameters of SM-1 were determined by a liquid chromatography-tandem mass spectrometry method. The enzyme kinetics of SM-1 obeyed the Michaelis-Menten equation. The V_max, K_m, and CL_int of SM-1 in HLMs were 14.5 nmol/mg protein/h, 6.32 μM, and 2.29 mL/mg protein/h, respectively.

Results: The chemical inhibition studies showed that CYP450 isoenzymes were responsible for SM-1 metabolism in HLMs, and CYP3A4 was the major CYP450 isoenzyme involved in the metabolism of SM-1; these findings were confirmed by using the human recombinant CYP3A4.

Conclusion: Through the identification of the biotransformation pathways and enzyme kinetics of SM-1, the metabolic enzymes for SM-1 in HLMs are characterized.

背景与目的：SM-1是一种新型合成的具有抗肿瘤活性的小分子化合物。SM-1 的代谢是一个需要评估的关键参数，以便在药物开发的早期阶段进一步了解药物的安全性和有效性。

方法：在本研究中，基于液相色谱-质谱法研究了 SM-1 的生物转化过程，包括代谢途径和主要代谢物。SM-1 与人肝微粒体孵育后，鉴定了五种代谢物，即 SM-1 的二氢二醇形成 (R1)、羟基化 (R2、R3 和 R5) 和脱苄基 (R4)，其中 R1 和 R4 是主要的代谢物。SM-1的酶动力学参数通过液相色谱-串联质谱法测定。SM-1 的酶动力学遵循 Michaelis-Menten 方程。HLM 中 SM-1的 V _max、K _m和 CL _int分别为 14.5 nmol/mg 蛋白质/小时、6.32 μM 和 2.29 mL/mg 蛋白质/小时。

结果：化学抑制研究表明CYP450同工酶负责HLMs中SM-1的代谢，CYP3A4是参与SM-1代谢的主要CYP450同工酶；这些发现通过使用人重组 CYP3A4 得到证实。

结论：通过SM-1的生物转化途径和酶动力学鉴定，对HLMs中SM-1的代谢酶进行了表征。