ABSTRACT
The fruits of Melia toosendan Sieb. et Zucc. (Meliaceae) are a source of bioactive limonoids that can be used as effective pesticides. In this study, two novel limonoids, 6-acetylsendanal and 6-ketocinamodiol, were isolated together with fourteen known compounds, namely four protolimonoids, six trichilin-class limonoids, and four C-seco limonoids. The structures of the new compounds were determined by extensive spectroscopic analyses (HR-ESI-MS, UV, IR, 1D and 2D NMR). The bioassay results revealed that eleven of the extracted limonoids exhibited interesting antifeedant activities against the larvae of Pieris rapae with AFC50 values in the range of 0.11-1.79â mm. Particularly, mesendanin H, with an AFC50 value of 0.11â mm, exhibited a higher activity than the positive control toosendanin. Information on new bioactive limonoids may provide further insight into M. toosendan as a source of bioactive components.