Identification de xanthones et de nouveaux arabinosides de C‐glucosides flavoniques dans Swertia perennis L.

Identification of xanthones and new arabinosides of flavone C‐glucosides from Swertia perennis L. – Seven tetraoxygenated xanthones [1,3,7,8‐tetrahydroxy‐xanthone (1); 1,8‐dihydroxy‐3,7‐dimethoxy‐xanthone (2); 1,7‐dihydroxy‐3,8‐dimethoxy‐xanthone (3); 1‐hydroxy‐3,7,8‐trimethoxy‐xanthone (4); 3,7,8‐trihydroxy‐xanthone‐xanthone‐1‐0‐β‐glucoside (5); 3,7,8‐trimethoxy‐xanthone‐1‐0‐primeveroside (6); 8‐hydroxy‐3,7‐dimethoxy‐xanthone‐1‐0‐primeveroside (7)] have been isolated chromatographically, using polyamide columns, from roots of Swertia perennis L. From leaves and stems of the same plant, six xanthones [1,5,8‐trihydroxy‐3‐methoxy‐xanthone (8); 1,5‐dihydroxy‐3‐methoxy‐xanthone‐8‐0‐β‐glucoside (9); mangiferin (10); 1; 4; 5] and four flavone C‐glycosides [iso‐orientin (11); isovitexin (12); iso‐orientin‐6″‐arabinoside (13); isovitexin‐6″‐arabinoside (14)] have also been isolated. Among these compounds, 7, 13 and 14 were not encountered before in nature. In the last two compounds, the position of arabinose on the C‐glucoside moiety of the flavone was established by 13C‐NMR. spectroscopy.