Enantioselectivity has been well recognized in the environmental fate and biological effects of chiral pesticides1-4. However, little is known about the disrupting effects of metals on the enantioselective behavior of chiral pesticides in organisms. Cis-bifenthrin (cis-BF) is a widely used chiral insecticide that contains two enantiomers: R-cis-BF and S-cis-BF. In this study, the disruption of Cd/Cu/Pb in the toxicity and enantioselective biotransformation of cis-BF in zebrafish were investigated. Co-exposure to Cd/Cu/Pb and rac-cis-BF or R-cis-BF caused increased mortality in zebrafish. EF (enantiomer fraction) values were decreased and the residue levels of each isomer were increased in rac-cis-BF+Cd/Cu/Pb groups, compared with rac-cis-BF alone group. Co-exposure to S-cis-BF and Cd caused lower EF value and decreased residue levels of S-isomer compared with S-cis-BF group, indicating Cd may potentiate the biometabolism of S-isomer in zebrafish. In R-cis-BF+Cd/Cu/Pb groups, EF values were decreased and the residue levels of R-isomer were increased relative to R-cis-BF group, indicating the inhibitory effects on the biometabolism of R-isomer by Cd/Cu/Pb. Altered gene expression of cytochrome P450 enzymes was observed in zebrafish liver in the combination groups, which might account for the enantioselective transformation of the isomers in zebrafish. Our findings demonstrated the addition of Cd/Cu/Pb resulted in higher proportion of R-cis-BF that is a more toxic isomer, which may be the underlying mechanisms accounting for the enhanced toxicity induced by co-exposure to BF and these metals. References: 1, Wang LM, Liu, WP, Yang CX, Pan ZY, Gan JY, Xu C, Zhao MR, Schlenk D. Enantioselectivity in estrogenic potential and uptake of bifenthrin. Environ. Sci. Technol. 2007, 31 (18) 6124-6128. 2, Wang C, Li ZY, Zhang Q, Zhao MR, Liu WP. Enantioselective induction of cytotoxicity by o, p’-DDD in PC12 cells: Implications of chirality in risk assessment of POPs metabolites. Environ. Sci. Technol. 2013, 47(8): 3909-3917. 3, Zhang Q, Zhao MR, Qian HF, Lu T, Zhang Q, Liu WP. Enantioselective damage of diclofop acid mediated by oxidative stress and Acetyl-CoA carboxylase in nontarget plant Arabidopsis thaliana. Environ. Sci. Technol. 2012, 46(15):8405-8412. 4, Ye J, Wang LM, Zhang ZJ, Liu, WP. Enantioselective physiological effects of the herbicide diclofop on cyanobacterium Microcystis Aeruginosa. Environ. Sci. Technol. 2013, 47(8):3893-3901.

Metals disrupt the enantioselective biotransformation of cis-bifenthrin in zebrafish

251st National Meeting (2016)

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