Enantioselective Estrogenic Effect And Developmental Tocixity In Zebrafish Embyro Of Pyraclofos

In recent years, there has been a growing concern about the environmental behavior and acute toxicity of chiral pyraclofos. However, data on endocrine disrupting effect and aquatic toxicity especially on vertebrate organisms is not available, let alone researches on enantioselectivity. In this study, enantioselective estrogenic activity of pyraclofos was investigated through the recombinant yeast-based assay and verified by molecular docking. Moreover, enantioselectivity in aquatic developmental toxicity mediated by immune-related molecular was performed on zebrafish embryo. The obtained results are summerized as follows:(1) Ten organophosphorus pesticides (OPs) with experimentally validated estrogenic activity were selected for molecular docking. Data presented herein indicated that hydrogen bonds, hydrophobic and electrostatic interactions are the major determinants to the difference of interactions of10OPs with estrogen receptor a (ERa) ligand binding domain (LBD) and ERβ LBD. The binding affinity of these OPs to ER LBD contributed, at least partly, to their different estrogenic activity.(2) The enantioselective estrogenic activity of pyraclofos was investigated by the combination of the recombinant yeast-based assay and molecular docking method. Results showed that:R-pyraclofos was more potential to induce the estrogenic effect compared with the non-estrogenic effect when exposure to the racemate and S isomer. Meanwhile, This enantioselectivity was further investigated by molecular docking, which revealed that ERa LBD formed two hydrogen bonds with R isomer while only one with S isomer. The different affinity between pyraclofos enantiomers and ERa LBD may contribute to the enantioselective estrogenic activity.(3) Enantioseletive developmental toxicity of pyraclofos was taken on zebrafish embryo. Results showed that the acute toxicity of pyraclofos on zebrafish embyro-larve was enantioselectivity and ranks as R>rac>S; Pyraclofos causes sublethal effect on zebrafish embryos including hatching delayed, yolk sac edema, pericardial edema, and crooked body. Moreover, R isomer was found more toxic than its antipode; The interleukin-1β (IL-1β gene) relevant to innate immune system was enantioselectively up-regulated by pyraclofos with the order of R>S. The molecular docking results showed strong hydrogen bonds formed between R isomers and ERa LBD, which helps explain the preference of R enantiomer binding to IL-1β over that of the S form.