Structure-dependent activity of phthalate esters and phthalate monoesters binding to human constitutive androstane receptor.
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.
†MOE Laboratory for Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Hong
H
Zhang
†MOE Laboratory for Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Zhaobin
Z
Zhang
‡Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, Gifu 501-1196, Japan.
Tsuyoshi
T
Nakanishi
†MOE Laboratory for Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Yi
Y
Wan
‡Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, Gifu 501-1196, Japan.
Youhei
Y
Hiromori
‡Laboratory of Hygienic Chemistry and Molecular Toxicology, Gifu Pharmaceutical University, 1-25-4 Daigaku-nishi, Gifu, Gifu 501-1196, Japan.
Hisamistu
H
Nagase
†MOE Laboratory for Earth Surface Process, College of Urban and Environmental Sciences, Peking University, Beijing 100871, China.
Jianying
J
Hu
D001665:Binding Sites; D000090702:Constitutive Androstane Receptor; D004305:Dose-Response Relationship, Drug; D004952:Esters / Q000737:chemistry* / Q000494:pharmacology*; D006801:Humans; D057927:Hydrophobic and Hydrophilic Interactions; D062105:Molecular Docking Simulation; D015394:Molecular Structure; D010795:Phthalic Acids / Q000737:chemistry* / Q000494:pharmacology*; D018160:Receptors, Cytoplasmic and Nuclear / Q000737:chemistry* / Q000378:metabolism; D013329:Structure-Activity Relationship
D000090702:Constitutive Androstane Receptor; D004952:Esters; D010795:Phthalic Acids; D018160:Receptors, Cytoplasmic and Nuclear; C032279:phthalic acid