ent-Kaurane Diterpenoids from Isodon albopilosus

Abstract

Nine new diterpenoids, albopilosins B-J (1-9), together with six known analogues, albopilosin A (10), macrocalyxin C (11), rabdokunmin C (12), excisanin (13), amethystonoic acid (14), and coetsanoic acid (15), were isolated from the aerial parts of Isodon albopilosus. The structures of 1-9 were established using spectroscopic methods including extensive 1D and 2D NMR analysis. The diterpenoids isolated were evaluated for their inhibitory activities against HepG2 (hepatoma) cells. Compounds 7 and 13 were the most active, with both having IC(50) values of <15 microM.