Study On The Stereoselectivity Degradation,Bioactivity,Toxicology And Ecotoxicology Assessment For Chiral Insecticide Ethiprole

The enantiomers of chiral pesticides have similar physical and chemical properties in achiral environments.Chiral pesticides are primarily used as mixtures of enantiomers,or racemates.It is hard to asymmetric synthesis and chiral separation of chiral pesticide in the development process.However,most of stereoisomers always show differ biological activity,toxicity and ecotoxicology in chiral environment.The risk assessment of chiral pesticide caused the extensive concern.Therefore,the achiral analysis of chiral pesticides are caused great challenge for the risk assessment of pesticides.In recent years,stereoselectivity of bioactivity,toxicity and risk assessment have attracted increasing attention.The systemic assessments of the stereoisomers of chiral pesticide are very important to make a more accurate benefit-risk evaluation.In the present study,the enantioselective degradation of chiral insecticides ethiprole in greenhouse vegetables and five soils were investigated.And the optical pure enantiomer of ethiprole were also selected to investigate their enantioselective bioactivity,toxicology and ecotoxicology to some insects,nontarget organisms and microbial diversity.Furthermore,the enantiomer of ethiprole are against Musca Rdlac GABACls were also investigated.The main results were listed as followed:1.The separation of ethiprole enantiomers was performed using reversed-phase HPLC.The influences of different mobile phase composition and temperature of chiral column were discussed for chiral separation of ethiprole.Satisfactory separation was obtained by using a mobile phase of methanol water(65:35,v/v)at ultraviolet(UV)detection 225 nm,the flow rate was 0.7 mL min-1,and the column temperaturewas set as 35 ?.And the Rs was arrived 2.522.The absolute configuration of ethiprole enantiomers was determined through the comparison of experimental and predicted ECD spectra.2.A simple and reliable method for the simultaneous determination of ethiprole enantiomers in fruits,vegetables,and soil samples was successfully established.An Florisil solid phase extraction(SPE)column was used by modified QuEchERS method for the cleanup of the samples.The method was evaluated by the specificity,matrix effect,linearity,precision and accuracy.The mean recoveries of two enantiomers ranged from 83.5-104.8%.The limit of detections(LODs)for two enantiomers in the six matrices were 0.008-0.012 mg kg-1,whereas the limit of quantifications(LOQs)were 0.019-0.049 mg kg-1.The RSD was ranged from 1.7%to 8.0%.The analytical method meet the requirement for simultaneous determination of ethiprole enantiomers in food and environmental samples.3.Stereoselective kinetic dissipation of ethiprole enantiomers in rat liver microsomes were investigated.The stereoselective degradation was occurred in rat liver microsomes.The EF values was decrease and was finally reached to 0.62.There is enantioconvergence was occurred in the incubation experiment.Only the(R)-ethiprole could translate into(S)-ethiprole.4.Stereoselective degradation of ethiprole enantiomers for vegetables was studied under field conditions.The degradation of ethiprole on four vegetables were accorded to first order kinetics.The(R)-ethiprole was preferentially degraded in cucumber,tomato,spinach and soil,and the EF values was ranged from 0.65 to 0.90.However,the degradation(S)-ethiprole was faster in pak choi,the EF values was finally reach to 0.15.There are different enzyme in different kinds of plants,which caused different stereoselective degradation of ethiprole.5.It was first time to report the stereoselective degradation of ethiprole in five different kinds of soil.The significant stereoselective degradation were observed,there is no(S)-ethiprole in Nanjing and Guangdong at 120 d.The EF values of soil in Jiangxi,Hainan and Jilin was reached to 0.11,0.10 and 0.26 at 180 d.For the incubation of pure enantiomers in Jilin soil,it was show that the(R)-ethiprole could translate into(S)-ethiprole.Therefore,the stereoselective behavior of ethiprole are caused by the enantioconvergence of enantiomers.6.The stereoselective bioactivity of ethiprole enantiomers were studied on Nilaparvata lugens and Acyrthosiphon pisum.The bioactivity of(R)-ethiprole was 2.2-4.3 times higher than that of(S)-ethiprole.And the rac-ethiprole was between them.The enantiomer of ethiprole are almost the same to against Musca Rdlac GABAC1s.The stereoselective bioactivity may be caused be the stereoselective absorption and degradation by the insects.This results have promoted further the mechanism of stereoselective bioactivity for chiral pesticide.7.The stereoselective toxicology of ethiprole enantiomers were studied onPseudokirchneriella subcapitata,Eisenia foetida and Trichogramma japonicum Ashmead.The rac-ethiprole have the high toxicity for the Pseudokirchneriella subcapitata,and the toxicity was follow the order:Rac->S->R-ethiprole.The toxicity of Rac-ethiprole was 1.55 and 2.95 times higher than the R and S-ethiprole.The toxicity is pretty different for Eisenia foetida.The Rac-ethiprole have the low toxicity and there have not different between the enantiomers.And the toxicity of S-ethiprole was around 6 times higher than S-ethiprole for Trichogramma japonicum Ashmead.The enantiomers are combined different for different protein crystal,which caused the different toxicity for different nontarget organism.8.The abundant phyla of soil microbial community are significantly different with the different treatment of ethiprole enantiomers in soil by high-throughput sequencing.Principal coordinates analysis of bacterial communities based on Bray-Curtis distance among different treatments.The coefficient of variance are significantly different with different time and enantiomers.It was show that the ethiprole have a close relationship with soil microbial community.'Network analysis showed that S-ethiprole application induced the more complex and closely linked microbial networks,which mainly dominated by bacteria,and the interactions within module and among mudules were better than R-ethiprole.And the R-ethiprole was behavior more damaging for soil microbial community.9.The high-throughput sequencing method is easy to find the microorganism phyla and genus which could enantioselective degradation and enantioconvergence of chiral ethiprole.The further OTU analytical method was tried to find out the microorganism species.It was show that the Phenylobacterium?OTU-10?23?32?38?135 and 228 have a close relationship with enantioselective degradation of chiral ethiprole.It is not only important to find out the enantioselective degradation and enantioconvergence of chiral ethiprole microorganism species,but also find out a good enzyme to achieve the asymmetric synthesis of chiral pesticide.