Synthesis And Insecticidal Activity Evaluation Of Tschimganin Analogs

Botanical pesticides refer to plants,crude plant extracts or the derivatives of the active ingredients used for the protection of crops and stored products from insect pests.These can be recommended as an ecochemical and sustainable strategy for the management of agricultural pests due to their biodegradable nature,systemicity after application,capacity to alter the behavior of target pests,and their favorable safety profile.Some plants of the genus Ferula have been used as pharmaceutical plants in many countries for centuries.Ferula is a rich source of biologically active compounds,In addition to treating a variety of disease,it is also commonly used to control various pests and has very important medicinal value.Therefore,in this report,we systematically designed and synthesized a novel series of tschimganin analogs and evaluated them for insecticidal activity.Their structure-activity relationship also was studied.The results are as follows:1.Using(+)-fenchyl alcohol and substituted benzoic acid as raw materials,52 tschimganin analogues had been obtained by catalytic esterification of N,N’-dicyclohexylcarbodiimide and 4-dimethylaminopyridine.All the target products had been characterized by ~1H NMR,13 C NMR and HRMS.2.The insecticidal activity of tschimganin analogues against H.armigera had been determined by chemical immersion method.Compounds ZQ-8 and ZQ-11 had showed certain insecticidal activities,among which ZQ-8 had had the best activity.This kind of compound has a great influence on the growth and development of H.armigera.After a period of medicinal treatment,the tested insects had showed small body,dark body color,unable to pupate or incomplete molting,pupal shell rupture,deformed pupae,pupation death and adult deformity after emergence,and smaller body size.Preliminary toxicological studies had showed that compared with CK,ZQ-8 had increased the activity of polyphenol oxidase(15%)and ZQ-11 had decreased the activity of polyphenol oxidase(59%);ZQ-8 and ZQ-11 had reduced carboxylesterase activity,respectively.56% and 33%;ZQ-11 had increased 20% glutathione S-transferase activity;ZQ-8 and ZQ-11 had increased alkaline phosphatase activity by 8% and 54%,by acid phosphatase activity by 29% and 36%.3.The acaricidal activity of tschimganin analogues against T.truncates and T.turkestani at a concentration of 50 μg/m L had been determined by leaf impregnation.The mortality rates of compounds ZQ-17 and ZQ-52 to T.truncates had been 84.44% and 82.43%,respectively,the LC50 values of the compounds ZQ-36 and ZQ-52 had been 21.62 μg/m L and 17.83 μg/m L,better than those of the control agents thiamethone.The structure-activity relationship study had showed that the 3-position nitro substitution,trifluoro substitution,3-position chlorine substitution,2-and 5-position bromine substitution and naphthyridine substitution on the benzene ring of the tschimganin analog acid moiety had contributed a lot to the activity;ZQ-18 with 4 nitro groups substituted on the benzene ring and ZQ-28 with 2,3,and 4 positions trifluoro-substituted ZQ-18 had had better acaricidal activity,and the corrected mortality rate had reached 74.33% and 78.78% at 24 hours,and corrected mortality at 48 hours.The 82.81% and 90.67% were achieved;the LC50 values of ZQ-16 and ZQ-18 had been 15.89 μg/m L and 15.11 μg/m L,respectively,which had been similar to the LC50 of the control agent.4.Tschimganin analogues had better insecticidal activity against A.gossypii of which 24 target compounds had LC50 <0.5 μg/m L.The structure-activity relationship study showed that in the electronwithdrawing group,the substitution of halogen could have increased the acaricidal activity,especially the fluorine atom(the LC50 of ZQ-25,ZQ-26 and ZQ-28 had been 0.13,0.17,0.15 μg/m L,respectively.),substitution of bromine atoms(LC50 for ZQ-33 and ZQ-34,respectively,0.23,0.13 μg/m L)and iodine atoms(LC50 for ZQ-37 is 0.12 μg/m L);whether monohalogen-substituted or polyhalogenated Substituted,the target compound had a good effect.In addition,the introduction of nitro(ZQ-47 LC50 is 0.18 μg/m L)and cyano(the LC50 of ZQ-22 and ZQ-23 are 0.22,0.24 μg/m L,respectively)also had certain benefits for the improvement of insecticidal activity.