“Click” reaction based synthesis of nimbolide derivatives and study of their insect antifeedant activity against Spodoptera litura Larvae

Abstract

A series of Nimbolide-triazole conjugates were synthesized through copper(I)- catalyzed azide–alkyne “click” chemistry approach and these derivatives (2–4, 2a–2l) were characterized using modern spectroscopic techniques. Antifeedant activities of these derivatives were studied on Tobacco Caterpillar, Spodoptera litura (F.) using no-choice leaf disk bioassay. Interestingly, the synthesized derivatives were more effective in reducing feedancy by insect species when compared to the parent nimbolide. Among the tested compounds, 2a, 2c, and 2d showed potent antifeedancy with ED50 values of 0.49, 0.95 and 0.97mg/cm2 against S. litura. Several of the analogs were also toxic or caused developmental abnormalities following leaf disc assay.