Chemical constituents of Swertia yunnanensis and their anti-hepatitis B virus activity.

Four new triterpenoids, sweriyunnangenin A (1), sweriyunnanosides A (2), B (3) and C (4), along with nineteen known compounds (5-23) were isolated from Swertia yunnanensis. Based on extensive spectroscopic analyses (1D- and 2D-NMR, HRESIMS, UV, IR, [α]D), the structures of sweriyunnangenin A (1), sweriyunnanosides A (2), B (3) and C (4) were elucidated as taraxer-14-ene-3α,6β-diol, oleanolic acid 28-O-β-D-glucopyranosyl-(1→2)-O-β-D-glucopyranoside, 2α,3β-di-hydroxyolean-12-en-28-oic acid 28-O-β-D-glucopyranosyl(1→6)-β-D-glucopyranosyl (1→6)-β-D-glucopyranosyl(1→2)-β-D-glucopyranoside and hederagenin 28-O-β-D-glucopyranosyl(1→6)-β-D-glucopyranosyl(1→6)-β-D-glucopyranosyl(1→2)-β-D-glucopyranoside, respectively. Twenty-two compounds were evaluated for their anti-HBV activities on the HepG 2.2.15 cell line in vitro, of which nine compounds showed potent anti-HBV activities. Compounds 1, 5-6, 14-16 and 19 showed activities against the secretion of HBsAg (IC50 values from 0.10 to 1.76 mM) and HBeAg (IC50 values from 0.04 to 1.41 mM), and compounds 11 and 13-16 exhibited significant inhibition on HBV DNA replication (IC50 values from 0.01 to 0.09 mM).