Four new triterpene saponins from Bupleurum rigidum L.

Abstract Four previously undescribed triterpene saponins (1-4) were isolated from the EtOH/H2O extract of the aerial parts of Bupleurum rigidum, together with a known structural analogue. Their structures were elucidated by analysis of 1D-(1H, 13C) and 2D-NMR (1H-1H COSY, TOCSY, ROESY, HSQC, HMBC) spectroscopic data and mass spectrometry (ESI- and HR-ESI-MS) and by comparison with those of related metabolites. An unusual structure was characterized as 3-O-β-D-glucopyranosyl-(1 → 2)-[ β-D-glucopyranosyl-(1 → 3)]- β-D-fucopyranosyl-21-O-β-D-glucoyranosyl-3β,16β,21β,23-tetrahydroxy-13,28-epoxyolean-11-ene (1). The three other compounds shared the same sugar sequence as 1 and differed by the st…