Liu Liu, Cui Hongyang, Huang Yixuan, Yan Hao, Zhou Yulan, Wan Yi
Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Laboratory for Earth Surface Processes, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Environ Res. 2023 Mar 1;220:115256. doi: 10.1016/j.envres.2023.115256. Epub 2023 Jan 10.
Metabolism generally transforms xenobiotics into more polar and hydrophilic products, facilitating their elimination from the body. Recently, a new metabolic pathway that transforms phenolic xenobiotics into more lipophilic and bioactive dimer products was discovered. To elucidate the role of cytochrome P450 (CYP) enzymes in mediating this cross-coupling metabolism, we used high-throughput screening to identify the metabolites generated from the coupling of 20 xenobiotics with four endogenous metabolites in liver microsomes. Endogenous vitamin E (VE) was the most reactive metabolite, as VE reacted with seven phenolic xenobiotics containing various structures (e.g., an imidazoline ring or a diphenol group) to generate novel lipophilic ethers such as bakuchiol-O-VE, phentolamine-O-VE, phenylethyl resorcinol-O-VE, 2-propanol-O-VE, and resveratrol-O-VE. Seven recombinant CYP enzymes were successfully expressed and purified in Escherichia coli. Integration of the results of recombinant human CYP incubation and molecular docking identified the central role of CYP3A4 in the cross-coupling metabolic pathway. Structural analysis revealed the π-π interactions, hydrogen bonds, and hydrophobic interactions between reactive xenobiotics and VE in the malleable active sites of CYP3A4. The consistency between the molecular docking results and the in vitro human cytochrome P450 evaluation shows that docking calculations can be used to screen molecules participating in cross-coupling metabolism. The results of this study provide supporting evidence for the overlooked toxicological effects induced by direct reactions between xenobiotics and endogenous metabolites during metabolic processes.
新陈代谢通常会将外源性物质转化为极性更强且亲水性更高的产物，从而便于它们从体内排出。最近，人们发现了一种新的代谢途径，该途径可将酚类外源性物质转化为亲脂性更强且具有生物活性的二聚体产物。为了阐明细胞色素P450（CYP）酶在介导这种交叉偶联代谢中的作用，我们采用高通量筛选方法来鉴定20种外源性物质与四种内源性代谢物在肝微粒体中偶联产生的代谢物。内源性维生素E（VE）是反应活性最高的代谢物，因为VE与七种含有各种结构（如咪唑啉环或双酚基团）的酚类外源性物质发生反应，生成了新型亲脂性醚类物质，如补骨脂酚-O-VE、酚妥拉明-O-VE、苯乙基间苯二酚-O-VE、2-丙醇-O-VE和白藜芦醇-O-VE。七种重组CYP酶在大肠杆菌中成功表达并纯化。重组人CYP孵育结果与分子对接结果相结合，确定了CYP3A4在交叉偶联代谢途径中的核心作用。结构分析揭示了反应性外源性物质与VE在CYP3A4可塑性活性位点之间的π-π相互作用、氢键和疏水相互作用。分子对接结果与体外人细胞色素P450评估结果的一致性表明，对接计算可用于筛选参与交叉偶联代谢的分子。本研究结果为代谢过程中外源性物质与内源性代谢物直接反应所诱导的被忽视的毒理学效应提供了支持证据。
