Biologically active dichapetalins from Dichapetalum gelonioides.

A phytochemical investigation of the toxic tropical plant Dichapetalum gelonioides led to the isolation and identification of 14 new dichapetalins (1-14) and the known dichapetalins A (15) and K (16). The structures of the new compounds were determined by analyses of their NMR, MS, electronic circular dichroism, and X-ray diffraction data. The esterification at C-25 by 4-hydroxyphenylpropanoic acid and the hydroxylation at C-2' are unique in this unusual class of natural products. In addition to the known cytotoxicity, an array of biological activities, including antifeedant, nematicidal, antifungal, and NO and AChE inhibitory activities, were observed for this class of compounds. These findings suggested that dichapetalin hybrid triterpenoids as a class have broad biologically active cellular functions including defense against insect herbivores and pathogens.