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Camptothecin Camptothecin has good insecticidal activity To further explore the the camptothecin structure and insecticidal activity relationship on the basis of the preliminary study, the parent compound camptothecin, structural modification, camptothecin series derivatives thereof. Through its insecticidal activity was measured to establish the structure-activity relationship model, and this model to predict the insecticidal activity of other camptothecin derivatives. The main results are as follows: 1. Parent compound camptothecin, to carry out a 5 - bit 7 - bit and 10 - bit and 20 - bit structural modification. 40 of the camptothecin derivative is synthesized by alkylation, oxidation, esterification step, all derivative structure was confirmed by FT-IR, 1 H NMR, LC-MS and other methods were used to characterize ; 2 by impregnation method for the determination of the camptothecin (CPT) derivatives of pine wood nematode Bursaphelenchus xylophilus insecticidal activity. Compared with the parent compound camptothecin 7-C, 20-C-substituted 20 - (S) - camptothecin derivative having a stronger nematicidal activity ,5-C-substituted derivatives of poor activity, 10 -C-substituted derivatives of the parent compound is quite active. 7 - benzyl - camptothecin, 7 - formyl - camptothecin, 7 - benzoyloxymethyl - camptothecin, 10 - benzoyloxymethyl - camptothecin, 20 - benzoyl the oxygen the methyl - camptothecin and 20 - fluorine - camptothecin at 24 h of pine wood nematode LC50 LC 50 were of 2.28,2.21,1.37,1.68,0.13 and 1.71 mg / L, significantly higher than that of the virulence of the parent compound camptothecin 12.18 mg / L; 3 leaf dipping method to test the activity of the camptothecin derivative 3-instar larvae of Spodoptera exigua Prodenia litura (Fabricius). In addition to the compound 7 - (hydroxymethyl) - camptothecin in section 12, 15 days insecticidal activity of 73.25% and 79.73%, the activity of other compounds are less than 60%, treatment of larvae survived to the pupal stage test insects, part of the development into a deformed pupae, not normal feathering; 5 etherification, esterification, 7 alkyl substituted 10 esterified derivatives reduce antifeedant activity of camptothecin, 20 esterification and hetero atoms introduced conducive antifeedant activity improved. 7 - (hydroxymethyl) - camptothecin, 7 - carboxy - camptothecin, 10 - methoxy - camptothecin Spodoptera litura showed higher antifeedant activity, the 24h and 48h antifeedant activity greater than 90 %; 4. camptothecin derivative kill pine wood nematode activity and its structure. Quantum chemical methods such as hydrophobic parameter log P as a variable to obtain the structure-activity relationship model pic 50 = 0.0374 2.5516 log P-0.6175 (log P) 2 ( R 2 = 0.8210, P lt; 0.05, N = 16). Verify the accuracy of this model, within a certain range of the model can accurately predict the other camptothecin derivatives insecticidal activity against the pine wood nematode. The structure and biological activity of camptothecin and its derivatives have a close relationship, it is necessary to further study camptothecin material structure-activity relationships and mechanism of action, and to provide a basis for the new pesticide lead compounds.
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