Influence Of Straight Chain Carbon Lengths On Phloem Mobility And Insecticidal Activity Of New Tralopyril Derivatives

Increasing bioavailability by improving phloem mobility of chemical pesticides is one of the important ways to reduce the application of chemical pesticides.Chlorfenapyr is the first choice of insecticide to control related pests of tea,but its active ingredient tralopyril showed non-phloem mobility and serious toxicity to plants.vectorizing pro-insecticide have been proposed to improve the above two phenomena,the phloem mobility and insecticidal activity of glutamic acid-tralopyril compounds have been confirmed in related studies.To further confirm the feasibility of tralopyril vectorizing pro-insecticide,nine glutamic acid-tralopyril compounds with different carbon chain length were designed and synthesized by click chemistry under the guidance of precursor pesticide theory.To study the insecticidal activity and phloem transport property of the conjugates to P.xylostella.and evaluate its toxicity on tea.The compounds with the best comprehensive effect was selected and studied their metabolism in the P.xylostella.The main results are as follows:1.Nine glutamic acid-tralopyril compounds with different carbon chain lengths were successfully designed and synthesized.By means of click chemistry and related deprotection reaction,nine glutamic acid-tralopyril compounds with different carbon chain length were synthesized by introducing the structure of glutamate into tralopyril.The synthesized final products were confirmed by ¹H NMR、¹³C NMR and API-ES analysis,and the synthesized products were all target even compounds.2.Tralopyril has an intolerable phytotoxicity to the plants,so chlorfenapyr was selected as the positive control.The phloem sap of conjugates 42-50 or chlorfenapyr was collected within two hours for detection.Ricinus cotyledons were incubated with200μM 42,43,44,45,46,47,48,49 and 50 for 2h.Upon observation,their concentrations in the phloem sap were about 24.84,41.88,36.77,30.58,37.10,34.85,41.47,37.86 and 38.89μM,respectively,When the cotyledons were incubated in chlorfenapyr solution at the same concentration,it was not detected in the phloem sap.The length of carbon chain affects the phloem,in which the conjugate 43 with carbon chain 3 is the highest.3.The results showed that the 9 conjugates had no toxicity to tea.no phytotoxic symptoms were observed up to 49 days after smearing of conjugates 42-50（score:0%–5%;grade 1）,but tralopyril showed obvious phytotoxic symptoms under 0.2m M（score:61%–70%;grade7）and 2m M（score:71%–80%;grade8）,which indicated that the introduction of glutamic acidmay solve the difficult phytotoxicity problem of tralopyril.4.The insecticidal activity of 9 compounds was studied.The results show ed that the conjugates 42-45 had better insecticidal activity.Then the insecticid al activity of the conjugates 42-45 pairs was studied and compared with chlorf enapyr.The LC₅₀values of 24h after conjugates 4 agents were 0.2397±0.0366m M（0.1644–0.3494m M）;0.4413±0.0647m M（0.3311–0.5882m M）;0.4400±0.0624m M（0.3309–0.5849m M）;0.4602±0.0655m M（0.3479–0.6087m M）.The length of carb on chain affects insecticidal activity,in which the conjugate 42 with carbon ch ain 2 has the highest insecticidal activity.5.Through the above research results,the conjugates 42 and 43 with deep research and development potential were preliminarily screened.Therefore,co mpounds 42 and 43 were selected to study the insecticidal mechanism of P.xy lostella.Tralopyril was detected in all the P.xylostella treated with conjugates42 and 43.The tralopyril content of 0.5950nmol/kg was detected in the P.xylo stella treated with conjugate 42 by LC-MS,the tralopyril content of 0.3172nmo l/kg was detected in the P.xylostella treated with conjugate 43 by LC-MS.Through the research in this paper,the toxicity to tea,phloem mobility and insecticidal activity of glutamic acid-tralopyril with different carbon chain length were studied,and the relationship between its structure and effect was clarified to provide reference,The coupling conjugates 42 and 43 with deep research and development potential were preliminarily screened.The feasibility of tralopyril vectorizing pro-insecticide was preliminarily confirmed.