Abstract
A new xanthone glucoside named isoswertianolin (2) was isolated from Swertia japonica and its structure was elucidated to be 5-O-β-glucopyranoside of bellidifolin by 1H and 13C nuclear magnetic resonance (NMR) spectroscopy. In connection with this study, the structure of swertianolin (1), a constituent of this plant, was reinvestigated by NMR spectroscopy, leading to the revision of its structure (the location of its glucosyl linkage) from 1-O-β-glucopyranoside of bellidifolin (3) to 8-O-β-glucopyranoside of 3. It follows that 1 is identical with the glucoside isolated from Gentiana campestris by Kaldas et al. in 1974. Analogously, the structure of norswertianolin (6), previously isolated from Swertia randaiensis HAYATA, was also revised, being formulated as 8-O-β-glucopyranoside of desmethylbellidifolin (7).
