Studies On Stereoselective Determination Method And Stereoselective Biological Effect Of Chiral Fungicide Furamepter

Amide fungicides are widely used in agricultural production.Due to the existence of chiral central atoms in the chemical structure of chiral amide fungicides,their enantiomers usually show stereoselective differences in the environment.However,the safety of chiral pesticides at the enantiomeric level has not been taken into consideration by traditional pesticide evaluation means.Furametpyr is a new type bactericidal amide fungicide with good application prospects due to its broad-spectrum and other characteristics.However,its analysis methods and biological effects at the enantiomeric level still remain unclear.In this paper,the chiral analysis method of furametpyr in paddy soil was established,the stereoselective activity of furametpyr enantiomers against four common pathogens was clarified,and the differences in the stereoselective toxicity against two aquatic non-target organisms were explored.The research results provide data support for the scientific and comprehensive evaluation of the safety of furametpyr at the enantiomeric level,and have good practical significance.Reversed-phase chiral stationary phase was used in combination with ultra-high performance liquid chromatography-mass spectrometry(UPLC-MS/MS)technology to establish UPLC-MS/MS instrument analysis method for the enantiomer chiral resolution by furametpyr through optimizing chromatographic conditions and mass spectrometry conditions of enantiomer separation by furametpyr;on the Chiralcel OX-3R chiral column,S-(-)-furametpyr flowed out first,and then R-(+)-furametpyr flowed out;the QuEchERS pretreatment method was optimized and the analysis method for furametpyr chiral residue in soil was established.The impact of different chiral columns,different mobile phases,different ratios of mobile phases,flow rate,and column temperature on furametpyr enantiomer separation was compared.Finally,the optimal chromatographic conditions for furametpyr chiral separation were determined:Chiralcel OX-3R chiral column was selected,and the optimal chromatographic separation conditions were:when the mobile phase was A:0.1%formic acid+10 mmol ammonium acetate aqueous solution;when the mobile phase was B:acetonitrile,flow rate of 0.6 mL/min,sample injection volume of 5 ?L,column temperature of 25 ?.The enantiomer achieved a good separation effect;the mass spectrometry conditions of the target chiral compounds were optimized by using MRM method.The electrospray ion source was selected with positive ionization(ESI+);capillary voltage:1.5 KV;backflush gas flow:50 L/Hr;desolvent gas flow:1000 L/Hr;desolvent gas temperature:600?;Ion source temperature:150?The differences in the bacteriostatic activity of furametpyr racemate and chiral isomer on four kinds of plant pathogenic fungi(Rhizoctonia spp.,Fusarium graminearum,Rhizoctonia solani,and Botrytis cinereal of strawberry)were compared by using mycelium growth rate method.The results showed that furametpyr racemate had the highest antibacterial activity against Rhizoctonia solani,and its antibacterial activity against Botrytis cinereal of strawberry was the weakest;The antibacterial activity of furametpyr against Rhizoctonia spp.,Botrytis cinereal of strawberry is in following order:S-(-)-furametpyr>Rac-furametpyr>R-(+)-furametpyr;for Fusarium graminearum and Rhizoctonia solani,the order of antibacterial activity is:S-(-)-furametpyr>R-(+)-furametpyr>Rac-furametpyr.S-(-)-furametpyr is the optimal enantiomer.After conducting the acute toxicity experiment of furametpyr and its enantiomers on two aquatic organisms(Daphnia magna and Selenastrum capricornutum),the results showed that furametpyr and its enantiomers have different toxicity against Daphnia magna to a certain degree,but the differences are not obvious.EC50 of Rac-furametpyr,R-(+)-furametpyr and S-(-)-furametpyr at 48h was 3.894mg/L,5.345 mg/L and 3.278mg/L,respectively.There exist small differences in the toxicity of furametpyr and its enantiomers against Selenastrum capricornutum,which can be sorted in following order from large to small:S-(-)-furametpyr>Rac-furametpyr>R-(+)-furametpyr;EC50 of Rac-furametpyr,R-(+)-furametpyr and S-(-)-furametpyr obtained at 72h was 0.233mg/L,0.172mg/L and 0.340mg/L.