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 1.83 mM, and compounds 1, 3, 5, 7 and 8 could inhibit the secretion of HBsAg with IC50 values from 0.24 to 1.06 mM.

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