Preparation and insecticidal activities of betulin-cinnamic acid-related hybrid compounds and insights into the stress response of Plutella xylostella L.

BACKGROUND The emergence and increasing intensification of insect pest resistance greatly shortens the service life of commercial insecticides. Hence, the continuous development of novel insecticides is extremely necessary. Discovering new insecticide molecules based on natural products with insecticidal activity has been a popular technique and has made outstanding contributions in this field. RESULTS A series of betulin-cinnamic acid-related hybrid compounds was prepared by molecular hybridization through the bridge of acyloxy groups and their chemical structures were unambiguously confirmed. Against A. pisum , compounds 2e , 3a-3e , 3g , 3i , 3j , and 3m showed complete antifeedant activity at 2 mg/mL; compound 5b exhibited 2.7 times the aphicidal activity of the precursor betulin. Against P. xylostella , compound 2l displayed 3.9 times the insecticidal activity of betulin. Meanwhile, some interesting structure–activity relationships were obtained. Furthermore, compound 2l could destroy the ultrastructure of midgut cells and significantly inhibit the activity of α-amylase in P. xylostella larvae. Molecular docking indicated that the lupane skeleton and p -nitrocinnamoyloxy groups played a key role in the binding of compound 2l to α-amylase. CONCLUSION Compounds 5b and 2l could be further optimized structurally as the secondary lead compounds for the discovery of novel insecticide molecules. © 2025 Society of Chemical Industry.