Five new secoiridoid glycosides and one unusual lactonic enol ketone with anti-HBV activity from Swertia cincta.

Five new secoiridoid glycosides, swericinctosides A and B (1-2), 9-epi swertiamarin (3), 2'-O-m-hydroxybenzoyl swertiamarin (4), 4″-O-acetyl swertianoside E (5), and one unusual lactonic enol ketone, 3-(hydroxymethyl ene) dihydro-2H-pyran-2, 4(3H)-dione (6), together with three known compounds, swertiaside (7), swertianoside C (8) and decentapicrin B (9) were isolated from Swertia cincta. The structures of the new compounds were determined by extensive spectroscopic analyses including 1D and 2D NMR, HRESIMS, UV, IR and [α]D spectra. Anti-HBV assay on HepG 2.2.15 cell line in vitro demonstrated that compounds 1-9 possessed inhibitory activity on HBV DNA replication with IC50 values from 0.05 to 1.83mM, and compounds 1, 3, 5, 7 and 8 could inhibit the secretion of HBsAg with IC50 values from 0.24 to 1.06mM.