Enantioselectivity is critical to the environmental fate and potential toxicities of chiral pesticides, which should be fully considered in risk assessment and regulatory decisions1. One bottleneck for the enantioselective studies of pesticides is that the absolute configuration of enantiomers is hardly identified after their chiral separations2. In this study, we combined the electronic circular dichroism (ECD) and time dependent density functional theory (TDDFT) in silico approach to determine the absolute configuration of typical pyrimidine fungicides, triazole fungicides and organophosphorus pesticides and further investigated their enantioselective degradation in soils. The absolute configurations of these pesticides were successfully assigned. The identified R- and S-isomers have quite different half-lives in soils, illustrating their dramatic enantioselective degradation behaviour. Pyraclofos was chosen for further toxicity toward zebrafish fish (Danio rerio) embryo and the aquatic toxicity after 96-hour exposure ranks as R>rac>S. Four toxicological endpoints, YSE, PE, CB, hatching rate inhibition showed an enantioselective developmental toxicity of chiral pyraclofos.References: Liu W, Gan J, Schlenk D, Jury WA, Enantioselectivity in environmental safety of current chiral insecticides. Proc Natl Acad Sci U S A. 2005, 102:701-706.Berova N, Bari LD, Pescitelli G. Application of electronic circular dichroism in configurational and conformational analysis of organic compounds. Chem Soc Rev, 2007, 36:914-931.

Assignment of absolute configuration and enantioselective aquatic toxicities of chiral pesticides

248th National Meeting (2014)

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