Triterpenoid saponins from Bupleurum marginatum var. stenophyllum

Twelve compounds were obtained by phytochemical investigation of 70% EtOH ( containing 0.5%NH3•H2O )extract of the roots of Bupleurum marginatum var. stenophyllum. Based on comparison of their spectral data, including HR-ESI-MS, ¹H-NMR, ¹³C-NMR data, with those of the literature, their structures were elucidated as saikosaponin b2 (1), saikosaponin a(2), saikosaponin b1(3), saikosaponin d (4), hydroxysaikosaponin a (5), saikosaponin b3 (6), saikosaponin c(7),saikosaponin i (8), saikosaponin f (9), chikusaikosides Ⅱ(10), saikosaponin s (11), and saikosaponin I(12). All compounds belong to olean-type triterpenoid saponin and compounds 1, 3, 5, 8-9,11, and 12 were isolated from this plant for the first time. At a concentration of 20 μmol•L⁻¹, compounds 2, 4, 6, 8, 11 and 12 showed strong inhibition activity against influenza virus WSN33 with the inhibition rate of 91.3%,88.6%,53.4%,61.3%,77.3% and 57.4%,respectively.