| The chiral pesticide dinotefuran is a third-generation nicotinic insecticide,it is widely used because of its excellent performance.Compared with traditional neonicotinoid insecticides,it has higher insecticidal activity,systemic and osmotic activity,it is one of the main pesticides in paddy fields in the world.In this paper,zebrafish,an aquatic animal,was used as the subject organism and dinotefuran was used as the research object.The enrichment and degradation of dinotefuran in zebrafish and its toxic effects were tested at enantiomer level by semi-static method.The main conclusions of the test are as follows:1.The enantiomers of dinotefuran were prepared by chiral separation of Rac-dinotefuran using Chiralpak IG chiral column combined with high performance liquid chromatography(HPLC).A liquid chromatography-tandem mass spectrometry(LC-MS/MS)method was developed for the determination of dinotefuran enantiomers in zebrafish and water.The results showed that average recoveries of dinotefuran enantiomers were 80.95-103.10%,the RSD values were 1.61-5.01%.The sensitivity,accuracy and precision of the developed method are in line with the experimental requirements.2.Through the acute and subchronic toxicity test,the acute toxicity of Rac-dinotefuran,R-(–)-dinotefuran,S-(+)-dinotefuran to zebrafish is in the order of R-(–)-dinotefuran > Rac-dinotefuran > S-(+)-dinotefuran.After exposure to an aqueous solution with a culture concentration of 0.2 and 1 mg/L for 28 d,compared with the blank control group,R-(–)-dinotefuran had a retarding effect on the growth of zebrafish.Rac-dinotefuran and S-(+)-dinotefuran have no significant effect on the growth of zebrafish.3.Accumulate-degradation experiment of zebrafish in exposed water was carried out,the results showed that the enrichment concentration of S-(+)-dinotefuran in zebrafish was higher than that of R-(–)-dinotefuran in the racemic and enantiomers treated groups,through a comparative experiment of exposure enrichment at different doses,there is dose-effect relationship between the concentration of dinotefuran in zebrafish and the concentration of exposure culture,the enrichment content of dinotefuran in zebrafish increases with the increase of the concentration of toxic medium.According to the degradation half-life of Rac-dinotefuran and enantiomer in zebrafish,showed that the degradation rate of R-(–)-dinotefuran in zebrafish is faster than that of S-(+)-dinotefuran.4.The oxidative stress test of zebrafish exposed to dinotefuran and enantiomers was studied.The results showed that Rac-dinotefuran and enantiomers produced oxidative stress toxicity to zebrafish.The Rac-dinotefuran and enantiomers had no significant effect on the protein content of zebrafish,R-(–)-dinotefuran has a greater impact on SOD activity,the Rac-dinotefuran and enantiomers on zebrafish GST activity are significantly different,Rac-dinotefuran has less effect on MDA content than enantiomers,after 14 d of exposure,Ach E activity was inhibited in the Rac-dinotefuran and R-(–)-dinotefuran exposure groups.5.Based on the Agilent 1290 Infinity LC ultra-high performance liquid chromatography system(UHPLC)and Triple TOF 6600 mass spectrometry technology,the small molecule metabolites in zebrafish were studied after exposure.The results showed that there were significant differences in metabolites between R-(–)-dinotefuran and S-(+)-dinotefuran.Intergroup comparison of R-(–)-dinotefuran and S-(+)-dinotefuran in the high-dose group showed that some compounds were generally up-regulated in the R-(–)-dinotefuran group,but were generally down-regulated in the S-(+)-dinotefuran group,indicated that there was a stereoselective toxicity between R-(–)-dinotefuran and S-(+)-dinotefuran.The different metabolites between R-(–)-dinotefuran and S-(+)-dinotefuran are mainly enriched in the aminoacyl-t RNA biosynthesis,biosynthesis of amino acids,ABC transporters and other related pathways. |
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