Ceanothane-type triterpenoids from Cyphostemma adenocaule.

Phytochemical investigation of the methanol extract of Cyphostemma adenocaule liana (bark and wood) led to the isolation of two new ceanothane-type triterpenoids, cyphostemmic acid A 1 and cyphostemmic acid B 2, together with the known triterpenoids 3–7, β-sitosterol and its glucoside. The structures of the isolated compounds were established by 1D- and 2D-NMR spectroscopy. Ozonolysis of cyphostemmic acid A 1, epigouanic acid A 3 and betulin 6 yielded semisynthetic derivatives, cyphostemmic acid C 8, cyphostemmic acid D 9, and 3β,28-dihydroxy-30-norlupan-20-one 10 respectively. Compounds 1–4, 6, 8–10 were tested in vitro, for their antiplasmodial activity against Plasmodium falciparum 3D7 strain and showed weak activity.