Seven new secoiridoids with anti-hepatitis B virus activity from Swertia angustifolia

Seven new secoiridoids, swertianglide (1) and swertianosides A-F (2-7), together with fifteen known compounds, were isolated from the whole plants of Swertia angustifolia. Their structures were elucidated on the basis of extensive spectroscopic analyses ([α](D), UV, IR, MS, 1D- and 2D-NMR). Fourteen compounds were evaluated for their anti-hepatitis B virus (HBV) activities on the Hep G 2.2.15 cell line in vitro. Compound 2, an unusual secoiridoid glycoside dimer, showed significant activities inhibiting the secretion of HBsAg (IC₅₀ 0.18 mM, SI 3.11) and HBeAg (IC₅₀ 0.12 mM, SI 4.67).