Cytotoxic triterpene dilactones from the stems of Kadsura ananosma.

Six new triterpene dilactones with a rare rearranged pentacyclic skeleton, longipedlactones K-P (1-6), and seven known analogues (7-13) were isolated from the stems of Kadsura ananosma. Compound 1 was found to possess a unique peroxide bridge between C-1 and C-9 in rings A and B. The structures of these new compounds were established on the basis of spectroscopic data analysis, especially of their 2D NMR spectra. In the evaluation of the in vitro cytotoxicity of these compounds against a small panel of human cancer cell lines, compounds 3, 7, 9, and 13 were found to be the most potent against HL-60 acute leukemia cell.