Studies On Enantiomeric Activity And Stereoselective Behavior Of Chiral Pesticide Ethofumesate In Organism And Environment

The enantiomeric activity and enantioselective behavior of ethofumesate in organisms and environment were studied based on the HPLC-Chiral Stationary Phase (CSP) technology to provide details of the performance and the fate of its enantiomers. It's the first report focused on the enantiomeric activity and stereoselective degradation of ethofumesate.The CDMPC CSP was synthesized and the chiral column was prepared which showed favorable enantiomeric recognition and separation potency. Resolution and preparation of ethofumesate enantiomers were achieved under the optimal semi-preparation conditions. The chemical structure of two elutes were identified by GC-MS, the optical property and the eluting order were determined by using the Circular Dichroism detector and polarimeter. The optical purity of each enantiomer was more than 97%.The bioactivity of the enantiomers was studied by bioassay with plant materials showing moderate sensitivity. Results indicated that the (+)-enantiomer showed significantly higher activity on cucumber and sorghum fresh weight inhibition than that of the (-)-enantiomer, and also higher than that of the racemate at the same rate. The two enantiomers, however, showed equal inhibition activity on wheat growth.The investigation was taken on involving stereoselective degradation of ethofumesate enantiomers in Kentucky bluegrass and tall fescue after foliar treatment with racemate. The results revealed the same preferential degradation of the (-)-enantiomer in both grass species. This selective style of degradation resulted in residues enriched with (+)-enantiomer in both species. The largest Enantiomeric Ratio (ER) of (+)/(-) was achieved above 3.0 at 5 days after treatment.The enantioselective degradation and pharmacokinetics of ethofumesate enantiomers in rabbits were investigated by a single intravenous (iv) administration at doses of 30 mg kg~-1 of racemate. Plasma concentration-time curves after iv administration were best described by an open two-compartment model. The concentration of the (-)-enantiomer decreased more rapidly than that of the (+)-enantiomer. Significant differences on pharmacokinetic parameters between two enantiomers indicated that the stereoselective behavior occurred in rabbits after iv administration with racemic ethofumesate. Similarly selective style was found in liver and bile, while reversed distribution tendency was observed in rabbit brain tissue with ER value lower than 1.The dissipation dynamic and the enantioselective degradation of ethofumesate in soils were studied by incubation with either racemate or optical pure enantiomers in different agricultural soils. The dissipation dynamic of ethofumesate in soils fitted to the first kinetic's law. The dissipation rate was greatly influenced by organic matter and texture style of each soil, while the light showed no influence on it. Preferential degradation of the (-)-enantiomer was observed in 3* soil, which led to the ER of 1.65 after 6 weeks of incubation with racemic ethofumesate. The stereoselective degradation causedsignificant difference on half-life between two enantiomers in this soil. The appearance of (+)-enantiomer after incubation with single (-)-enantiomer revealed the enantiomeric inversion of (-)-isomer to its antipode. While no obvious stereoselective degradation or enantiomeric inversion were observed in other test soils.