The Effect Of Parabens On Androgen Receptor And The Toxicity Of Phthalates To Vibrio Oinghaiensis Sp.-67

Parabens and phthalates(PAEs)were widely incorporated in the personal care products and consumer goods used as antimicrobial preservative and plasticizer.Their residues were frequently detected in various matrices and biological body.However,their human health and ecoenvironment risk have been lessly investigated.The different side chain of parabens and phthalate esters(PAEs)were chosen as the target.The androgen receptor(AR)disrupting effect of parabens was evaluated.The effect of porcine liver ester-mediated hydrolysis towards the AR disrupt activities was determined.The molecular mechanism of AR disrupting effect was further elucidated using molecular docking.The single and binary joint toxicities of PAEs and cadmium(Cd)were investigated using the Vibrio qinghaiensis.sp.-Q67 as the model.The acute toxicity of PAEs was evaluated in the presence of Cd and was further predicted using concentration addition(CA)and independent action(IA)model.The effect of side chain type and length on the toxicty of parabens and PAEs was investigated.The obtained results were summarized as following:(1)The AR disrupting effect of parabens with different sizes of alkoxyl and aryloxy side chains were investigated using human recombinant AR yeast two hybrid assay.Parabens with alkoxyl side chains increased anti-androgenic activities with the side chain length decreased from 4 to 1,and no AR disrupting effect occurred for parabens with the side chain length equals to 7,8 and 12.Parabens with aryloxy side chain such as benzyl paraben and phenyl paraben have the strongest anti-androgenic activity in comparison of parabens with alkoxyl side chain.Molecular docking revealed that parabens mainly form hydrogen bonds with Thr877 and Asn705,bearing similar binding mode to dihydrotestosterone(DHT).There is a significant correlation between the anti-androgenic activities of parabens and their binding energies(R~2=0.84,P<0.05).To further investigate the effect of side chain of parabens to the anti-androgenic activities,the porcine liver esters were used to hydrolyse the parabens.The anti-androgenic activities of parabens were completely diminished following the hydrolysis of porcine liver esters.The hydrolysis products of parabens were identified by high performance liquid chromatography coupled with ultraviolet detector(HPLC-UV)and ultra-performance liquid chromatography coupled with the secondary mass spectrometry(UPLC-MS/MS)and the 4-hydroxybenzoic acid were formed.The side chain types of parabens have significant influence on porcine liver esterase-mediated hydrolysis.Parabens with aromatic side chains are less prone to hydrolysis in comparison with parabens with alkyl side chains.(2)We investigated the single and joint toxicity of commonly used PAEs and Cd using freshwater luminescent bacteria Vibrio qinghaiensis sp.-Q67 as the model.The median effective concentration(EC50)of benzyl butyl phthalate(BBP),dibutyl phthalate(DBP),diethyl phthalate(DEP),dimethyl phthalate(DMP),diisooctyl phthalate(DIOP)and di-n-octyl phthalate(DOP)were determined to be higher than 100 mg/L(DMP:134.4 mg/L;DEP:283.1 mg/L;DBP:895.1 mg/L),indicating very weak toxicity toward Vibrio qinghaiensis sp.-Q67.The toxicity of single PAEs showed a significant linear relationship with Log Kow,indicating the hydrophility-dependent toxicities(R~2=0.8961,P<0.05).The toxicities of binary mixture of PAEs were further in silico evaluated using the independent action(IA)model and concentration addition(CA)model.The DMP-DEP,DEP-DBP or DMP-DBP exhibited antagonistic effects with the toxic unit(TU)value higher than 1.2.The joint toxicities of the binary mixtures of DMP,DEP or DBP with Cd were simple additive with the TU values ranging from 0.8 to 1.2.Our results indicated the potentially higher risk of PAEs in the presence of Cd.