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.