CYP3A 亚家族成员在人体药物代谢酶中含量最多且底物谱最大，是药物代谢反应中最主要的限速酶。人体CYP3A4/3A5间，及人与动物CYP3A亚型间的底物谱均具有广泛重叠性，但各亚型的代谢行为却各具特色，这给临床安全用药及临床前动物模型的选择都带来极大的困扰。本项目采用结构完全不同两类化合物五味子木脂素类化合物和蟾蜍甾烯类化合物作为模式化合物，系统评价CYP3A各亚型代谢行为与催化机理的差异性。拟通过体外代谢实验开展系列模式化合物与CYP3A各亚型的相互作用研究，并从定性和定量两方面考察不同取代基及化学修饰对其CYP3A亚型选择性及代谢行为差异的影响。同时结合分子模拟和定点突变技术，揭示影响CYP3A亚型选择性的大分子酶的关键氨基酸位点，最终为设计和开发高选择性的CYP3A亚型配体工具分子及新药研发中临床前适宜动物模型的选择提供理论依据和研究基础。

CYP3A isoforms are the most important drug-metabolizing enzymes (DME), which account for the majority of DME present in human and get involved in the metabolism of most of the marketed drugs with various chemical structures. The substrates spectrum for human CYP3A4/CYP3A5 and CYP3A isoforms of human and animal species overlaps extensively, while the metabolic behaviors between each isoforms have its own characteristics, which poses great challenges to clinical safe medication and preclinical selection of suitable animal models. This project will adopt schisandra lignans and bufodienolides as model compounds to assess the differences of metabolic behaviors and the catalytic mechanism. In vitro metabolic experiments will be conducted to assess and compare the interaction behaviors between series of model compounds and CYP3A isoforms. Based on the above research, we will investigate the selectivity of CYP3A isoforms and the influence of the different substituent and chemical modification on the metabolic differences from qualitative and quantitative aspects. In addition, this project will uncover the effect of key amino acid in CYP3A isoforms on the metabolic behaviors variation by using the technique of molecular modelling and site-directed mutagenesis, and ultimately provide theoretical basis for the design and development of high-selective ligand tools of CYP3A isoform and selection of suitable preclinical animal models in new drug research and development.