Longipedlactones A-I, nine novel triterpene dilactones possessing a unique skeleton from Kadsura longipedunculata

Nine novel triterpene dilactones with an unprecedented rearranged pentacyclic skeleton, longipedlactones A-I (1-9), have been isolated from the leaves and stems of Kadsura longipedunculata Finet et Gagnep (Schisandraceae). Their structures were determined on the basis of comprehensive spectroscopic analysis and single-crystal X-ray structure determination. A biogenetic pathway for longipedlactone A (1) was also proposed. Compounds 1-3, 6, and 8 showed significant cytotoxicity against A549, with HT-29 and K562 cell lines having IC50 values of 0.84-11.38 μM in vitro.