Structure-Dependent Activity of Phthalate Esters and Phthalate Monoesters Binding to Human Constitutive Androstane Receptor

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• 作者：Hong Zhang ; Zhaobin Zhang ; Tsuyoshi Nakanishi ; Yi Wan ; Youhei Hiromori ; Hisamistu Nagase ; Jianying Hu
• 刊名：Chemical Research in Toxicology
• 出版年：2015
• 出版时间：June 15, 2015
• 年：2015
• 卷：28
• 期：6
• 页码：1196-1204
• 全文大小：566K
• ISSN：1520-5010

文摘

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 渭M (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 渭M, respectively, higher than those of their corresponding phthalate esters (1.45 渭M for DEP and 0.83 渭M for DIBP), whereas TBMEHP (0.66 渭M) was much lower than TBHP (>10² 渭M). 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, 蟺鈥撓€ 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.