| In recent years,new amide fungicides have been widely registered and used on crops.However,most of these fungicides contain chiral symmetry centers,and their enantiomers may have stereoselective differences in organisms and the environment.Therefore,from the enantiomeric level The application safety evaluation of such fungicides is a scientific problem that needs to be solved urgently.Sedaxane is a typical representative of such new chiral amide fungicides.It has the characteristics of high efficiency and versatility.At present,its safety evaluation at the enantiomeric level has not been reported.This thesis starts with the four enantiomers of Sedaxane,and explores the stereoselective degradation,biological antibacterial activity and non-target biological toxicity of Sedaxane which can be more accurate and safe for Sedaxane.Sexual evaluation provides scientific basis,and the main research results are as follows:1.Using ultra performance liquid chromatography-tandem mass spectrometry（UPLC-MS/MS）combined with reversed-phase chiral stationary phase technology,a method for the analysis of the enantiomeric residues of triflufenacil was established.The results showed that on the basis of using CHIRALPAK?IG-3 chiral separation column,with 5mmol ammonium acetate solution+0.1%formic acid and acetonitrile as mobile phases,the retention times of the four enantiomers of Sedaxane were 11.79 min,13.70 min,15.07min and 27.79 min,the resolutions reached 2.03,1.46 and 9.38;the absolute configuration and pairing of Sedaxane were determined by electronic circular dichroism（ECD）and specific rotation measurement.The order of the efflux of the enantiomers;in addition,the addition and recovery results show that the average recovery rate of the four enantiomers of Sedaxane in rice plants and wheat plants was between 83.1%～98.2%,and the precision（RSD）was 1.2%～8.4%,the lowest limit of quantification LOQ was 5.0μg/kg.2.The selective degradation trend of Sedaxane isomers in rice and wheat plants was studied by field application.The results showed that the degradation of Sedaxane isomers in rice and wheat plants could meet the kinetic equation（first order）,and the T1/2（half-life）of the enantiomers 1R,2S-（+）-Sedaxane and 1R,2R-（-）-Sedaxane degradation in rice plants was smaller than that in wheat plants,The T1/2（half-life）of the enantiomers 1S,2S-（+）-Sedaxane and 1S,2R-（-）-Sedaxane degradation in rice plants was larger than that in wheat plants.The enantiomeric fractions EF1 and EF2 of rice plants ranged from 0.439 to 0.552and 0.396 to 0.498,respectively,with EF2<0.5 indicating that 1S,2S-（+）-Sedaxane was preferentially degraded on rice plants;the enantiomeric fractions EF1 and EF2 of wheat plants ranged from 0.421 to 0.494 and 0.386 to 0.509,respectively,with EF1<0.5,and the maximum value of EF2 was close to 0.5,indicating that 1R,2S-（+）-Sedaxane,1S,2S-（+）-Sedaxane was preferentially degraded in wheat plants.The diastereomeric fraction DF of rice ranged from 0.848 to 0.93,and the degradation trend of 1R,2S-（+）-Sedaxane and 1R,2R-（-）-Sedaxane had little difference with that of diastereomers 1S,2S-（+）-Sedaxane and 1S,2R-（-）-Sedaxane;the diastereomeric fraction DF of wheat ranged from 0.743 to 0.896,and showed a decreasing trend within 30 days,indicating that 1S,2S-（+）-Sedaxane and 1S,2R-（-）-Sedaxane was prior to the non enantiomers 1R,2S-（+）-Sedaxane and 1R,2R-（-）-Sedaxane in wheat plants.3.The method of mycelial growth rate should be referred to to carry out the activity difference of racemic and isomeric Sedaxane against pathogenic fungi（Rhizoctonia solani,Rhizoctonia cerealis,Rhizoctonia solani,Fusarium graminearum,Sclerotinia sclerotiorum,Phytophthora capsici）.The results showed that the racemic form of Sedaxane had the best inhibition on Rhizoctonia solani and the worst inhibition on Sclerotinia sclerotiorum of rape;the activity of Sedaxane enantiomers to Rhizoctonia solani,Fusarium graminearum and Sclerotinia sclerotiorum of rape was as follows:1S,2S-（+）-Sedaxane>1S,2R-（-）-Sedaxane>1R,2S-（+）-Sedaxane>1R,2R-（-）-Sedaxane;The activity against Phytophthora capsici as follows:1S,2S-（+）-Sedaxane>1R,2R-（-）-Sedaxane>1S,2R-（-）-Sedaxane>1R,2S-（+）-Sedaxane.The activity of the racemates was within four enantiomers.For Rhizoctonia solani fungus,Rhizoctonia cerealis fungus,Rhizoctonia solani fungus,Fusarium graminearum fungus,rape Sclerotinia sclerotiorum and Phytophthora capsici 1S,2S-（+）-Sedaxane and 1S,2R-（-）-Sedaxane the EC50 ratios of were 0.51,0.62,0.66,0.84,0.93 and0.94,1S,2S-（+）-Sedaxane was the best enantiomer;1R,2R-（-）-Sedaxane and 1R,2S-（+）-Sedaxane the EC50 ratios of were 2.17,2.05,2.08,3.29,1.01,0.47,1R,2R-（-）-Sedaxane was the best enantiomer,and among the other pathogens,1R,2S-（+）-Sedaxane was the best enantiomer.4.To carry out the stereoselective toxicity studies of the racemate and four enantiomers of Sedaxane on the aquatic organisms Selenastrum capricornutum and Daphnia magna.The results showed that Rac-Sedaxane and its enantiomers 1R,2S-（+）-Sedaxane,1R,2R-（-）-Sedaxane,1S,2S-（+）-Sedaxane,1S,2R-（-）-Sedaxane the acute toxicity data of to Selenastrum capricornutum are 0.963 mg/L,0.646 mg/L,0.532 mg/L,1.486 mg/L,and 1.348 mg/L is poisoning,the acute toxicity at 72h after treatment is ranked as follows:1R,2R-（-）-Sedaxane>1R,2S-（+）-Sedaxane>Rac-Sedaxane>1S,2R-（-）-Sedaxane>1S,2S-（+）-Sedaxane.The acute toxicity of 1R,2R-（-）-Sedaxane is 1.21 times that of 1R,2S-（+）-Sedaxane,and the acute toxicity of 1S,2R-（-）-Sedaxane is 1S,2S-（+）-Sedaxane is 1.11 times,and the toxicity difference between the enantiomers is not obvious.For Daphnia magna Rac-Sedaxane and its enantiomers 1R,2S-（+）-Sedaxane,1R,2R-（-）-Sedaxane,1S,2S-（+）-Sedaxane and 1S,2R-（-）-Sedaxane the toxicity data of are 0.681 mg/L,0.553 mg/L,0.543mg/L,0.653 mg/L and 0.559 mg/L,respectively high toxicity,the acute toxicity at 48h after treatment is ranked as follows:1R,2R-（-）-Sedaxane>1R,2S-（+）-Sedaxane>1S,2R-（-）-Sedaxane>1S,2S-（+）-Sedaxane>Rac-Sedaxane.The acute toxicity of 1R,2R-（-）-Sedaxane is1.02 times that of 1R,2S-（+）-Sedaxane;the acute toxicity of 1S,2R-（-）-Sedaxane is 1S,2S-（+）-Sedaxane is 1.17 times,indicating that the toxicity difference between the enantiomers is not obvious.In conclusion,1S,2S-（+）-Sedaxane is an enantiomer with high efficiency to target organisms and low toxicity to non target aquatic organisms.It is suggested that it can be developed as a single enantiomer to improve control efficiency and reduce environmental risk. |
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