Two new sesquiterpenes from Alisma orientalis.

Two new sesquiterpenoids named alismorientols A (1) and B (2) were isolated from the rhizomes of Alisma orientalis collected in Sichuan province, People's Republic of China. Their structures were elucidated based on spectroscopic analyses (1D and 2D NMR data including HSQC, HMBC, COSY, and ROESY) and X-ray crystallographic analysis. Anti-hepatitis B virus (HBV) bioassay revealed that compound 1 showed moderate anti-HBV activity in vitro with IC50 for HBsAg: 1.1 microM, for HBeAg: 14.7 microM.