Dichapetalins from the Twigs of Dichapetalum longipetalum with Cytotoxic Activities.

Continued efforts to expand the structural diversity of dichapetalins and explore further the cytotoxic structure-activity relationships have led to the isolation of 17 undescribed analogues, dichapelonins A-Q ( 1 - 17 ), and three known compounds ( 18 - 20 ) from the twigs of Dichapetalum longipetalum . Compounds 1 - 17 comprise five compound classes as classified by varied C6-C2 conjugates at the A ring of the 13,30-cyclodammarane skeleton, and their structures were determined by spectroscopic data analysis, experimental electronic circular dichroism measurements, and X-ray crystallography. Biological tests revealed compounds 1 - 7 with a phenyl-butadiene appendage to be the most potent cytotoxic compound type of those evaluated.