Identification of new limonoids from Swietenia and their biological activity against insects

BACKGROUND: Natural limonoids are one group of compounds being studied for their insecticidal properties. To discover new limonoids with better activities, analogs were prepared via acylation and hydrolysis, and bioassayed. RESULTS: Analogs were identified using one- and two-dimensional (COSY, HMQC and HMBC) (1) H and (13) C NMR, IR and MS. 3-O-Isovalerylswietenolide (13) and 3-O-isobutyrylswietenolide (14) showed excellent antifeedant activity, with DC(50) values of 0.19 and 0.009 mg L(-1) respectively, compared with the natural limonoid swietenolide (80.6 mg L(-1) ) against fourth-instar Spodoptera frugiperda (JE Smith) larvae. CONCLUSION: This work shows that limonoid analogs prepared through semi-synthesis can be used as lead compounds for the development of new insecticides.