Zhang Hong, Zhang Zhaobin, Nakanishi Tsuyoshi, Wan Yi, Hiromori Youhei, Nagase Hisamistu, Hu Jianying
†MOE Laboratory for Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
‡Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, Gifu 501-1196, Japan.
Chem Res Toxicol. 2015 Jun 15;28(6):1196-204. doi: 10.1021/acs.chemrestox.5b00028. Epub 2015 May 13.
The present study investigated the human constitutive androstane receptor (CAR) binding activities of 23 phthalate esters and 10 phthalate monoesters using a fast and sensitive human CAR yeast two-hybrid assay. Of 23 phthalate esters, 16 were evaluated as positive, and the 10% relative effective concentrations (REC10) ranged from 0.28 (BBP) to 29.51 μM (DEHP), whereas no obvious binding activities were found for the phthalate esters having alkyl chains more than six carbons in length. Of 10 phthalate monoesters, only monoethyl phthalate (MEP), monoisobutyl phthalate (MIBP), and mono-(2-ethyhexyl) tetrabromophthalate (TBMEHP) elicited human CAR binding activities. The REC10 values of MEP and MIBP were 4.27 and 14.13 μM, respectively, higher than those of their corresponding phthalate esters (1.45 μM for DEP and 0.83 μM for DIBP), whereas TBMEHP (0.66 μM) was much lower than TBHP (>10(2) μM). A molecular docking method was performed to simulate the interaction modes between phthalates and human CAR, and active phthalates were found to lie at almost the same site in the human CAR pocket. The docking results suggest that the strong binding of phthalates to human CAR arises primarily from hydrophobic interactions, π-π interactions, and steric effects and that weak hydrogen bonds and weak halogen bonds greatly contribute to the high binding activity of TBMEHP. In conclusion, the current study clarified that an extensive array of phthalates are activators of human CAR.
本研究采用快速灵敏的人组成型雄烷受体（CAR）酵母双杂交试验，研究了23种邻苯二甲酸酯和10种邻苯二甲酸单酯与人CAR的结合活性。在23种邻苯二甲酸酯中，16种被评估为阳性，10%相对有效浓度（REC10）范围为0.28（邻苯二甲酸丁苄酯）至29.51μM（邻苯二甲酸二（2-乙基己基）酯），而对于碳链长度超过6个碳的邻苯二甲酸酯未发现明显的结合活性。在10种邻苯二甲酸单酯中，只有邻苯二甲酸单乙酯（MEP）、邻苯二甲酸单异丁酯（MIBP）和单（2-乙基己基）四溴邻苯二甲酸酯（TBMEHP）引发了人CAR结合活性。MEP和MIBP的REC10值分别为4.27和14.13μM，高于其相应邻苯二甲酸酯（DEP为1.45μM，DIBP为0.83μM），而TBMEHP（0.66μM）远低于TBHP（>10²μM）。采用分子对接方法模拟邻苯二甲酸酯与人CAR之间的相互作用模式，发现活性邻苯二甲酸酯位于人CAR口袋中几乎相同的位点。对接结果表明，邻苯二甲酸酯与人CAR的强结合主要源于疏水相互作用、π-π相互作用和空间效应，而弱氢键和弱卤键对TBMEHP的高结合活性有很大贡献。总之，本研究阐明了大量邻苯二甲酸酯是人CAR的激活剂。
