Synthesis And Preliminary Study On Insecticidal Activities Of Cholesterol Oxime Esters Derivatives Containing N-Benzylmatrinic Acids

Matrine is an alkaloid isolated from Sophora flavescens Ait,and shows lots of bioactivities such as insecticidal,antibacterial,and growth regulation activities.Cholesterol is a steroid compound,mainly found in human and animal fat,blood,brain and spinal cord.Cholesterol and its derivatives have antibacterial,antitumor and antiviral activities.In order to further study and expand the application of matrine and cholesterol in agriculture,in this paper matrine and cholesterol were used as substrates to synthesize a series of cholesterol oxime esters derivatives containing N-benzylmatrinic acids.Their insecticidal effects on Mythimna separata Walker,Aphis citricola van der Goot and Plutella xyllostella Linnaeus were tested.The main results were as follows:（1）37 derivatives（20 target compounds and 17 intermediates）were designed and synthesized,and 20 cholesterol oxime esters derivatives containing N-benzylmatrinic acids were new compounds.Their structures were confirmed by ¹H NMR,IR,melting points,and optical rotation.Compound 4a was further determined by X-single crystal diffraction.（2）The insecticidal activity of compounds against early 3rd-instar larvae of M.separata was tested at 1.0 mg/m L by leaf-dipping method.The final mortality rates（FMRs）of compounds 2d,IIb,IId,IVa,IVd and IVe were 51.7%,55.1%,48.2%,62.0%,51.7%and48.2%,respectively,which were higher than that of the positive control toosendanin（44.8%）.（3）The insecticidal activity of compounds against A.citricola was tested at a dose of0.04μg/nymph by the micro-drop method.Compounds IIIe,IVd and IVe displayed good insecticidal activity,and their LD₅₀ values were 0.045,0.042 and 0.052μg/nymph,respectively.Especially the insecticidal activity of IVd was 4.3 folds of cholesterol(LD₅₀:was 0.179μg/nymph),and 2.2 folds of matrine(LD₅₀:0.091μg/nymph).（4）The insecticidal activity of compounds against early 3rd-instar larvae of P.xyllostella was tested at a dose of 20μg/larva by leaf-dipping method.Compounds IIIe and IVe showed good insecticidal activity,and their 48 h mortality rates were 51.2%and 46.5%,respectively,which were comparable to that of toosendanin（46.5%）.The preliminary structure-activity relationships showed that introduction of4-methoxybenzoyl at the C-3 position of cholesterol,and introduction of benzyl on the N of matrinic acid could lead to potent compound against M.separata;introduction of4-chlorobenzoyl at the C-3 position of cholesterol,and introduction of the fluorine atom on the N-benzyl of matrinic acid could lead to potent compound against A.citricola;introduction of 4-methoxybenzoyl at the C-3 position of cholesterol,and introduction of the halogen atom on the N-benzyl of matrinic acid could give potent compounds against A.citricola;introduction of benzoyl at the C-3 position of cholesterol,and introduction of the electron-withdrawing or electron-donating group on the N-benzyl of matrinic acid could result in potent compounds against P.xyllostella.These results will provide a basis for the synthesis of matrine and cholesterol derivatives and study their insecticidal activities in the future.