Structure-insecticidal Activity Relationship On Camptothecin Derivants

In an attempt to find the insecticidal activity of camptothecin derivatives and aim to clarifycorelationship between chemical construction and insecticidal activities of Camptothecin and itsderivatives, series of Camptothecin derivatives were synthesized via structure modification.Andthe nematocidal activity against Bursaphelenchus xylophilus was studied using these compounds.Additionally, the bioactivity results were used to construct quantitative structure-activity relationship models which can be used to establish the activity of other Camptothecin derivatives.Thecontents and results were summarized as follows:1.40 camptothecin derivatives were synthesized via a simple modification with alkylation,oxidation and esterification at 5-C, 7-C, 10-C and 20-C, and their structures were identified by FT-IR, LC-MS and 1^H NMR.2. Nematocidal activity of 20-(S)-camptothecin derivants against Bursaphelenchus xylophiluswas tested by mmersion method. The results showed that nematocidal activity of 7-C and 20-C-su-bstitution camptothecin derivatives were obviously higher than 5-C and 10-C- substitution Camp-tothecin derivatives. Especially the compounds 7-CH₂C₆H₅-CPT , 7-CHO-CPT, 7-CH₂OC-OC₆H₅-CPT, 10-CH₂OCOC₆H₅-CPT , 20-CH₂OCOC₆H₅-CPT and 20-F-CPT exhibited more potent0.13 and 1.71mg/L respectively are higher than 20-(S)-camptothecin of 12.18 mg/L after 24 h.nematocidal activity than 20-(S)-camptothecin,with LC₅₀ values were 2.28, 2.21 ,1.37,1.68,3. The activity of derivants to third-instar larvae of Spodoptera litura was tested by Lobular dishmethod. The poisonous activity of all the compounds were low except 7-CH₂OH-CPT which poisonousactivity were 73.25% and 79.73% after 12th and 15th days respectively.And during larvaedevelopment,some larvae growed abnormal pupa; The Antifeedant activity after 24h and 48h ofCamptothecin with 5-etherification, 5-esterification,7-alkylation and 10- esterification was degraded,while 20- esterification and introduction heteratom enhance the antifeedant activity . Antifeedantactivity of three Camptothecin derivatives, 7-CH₂OH-CPT,7-COOH-CPT and 10-O-CH₃-CPTdisplayed higher antifeedant activity (>90%)at 24h and 48h than Camptothecin.4. Structure-nematocidal activity relationship of 20-(S)-camptothecin derivants against Burs-aphelenchus xylophilus were researched, Structure-function relationship model was established aspIC₅₀ = 0.0374 + 2.5516 log P- 0.6175 (log P)²( R² = 0.8210 , P<0.05, N = 16) .Other compoundsactivities can be predicted according to this model precisely.