Dammarane-saponins of sanchi-ginseng, roots of Panax notoginseng (Burk.) F.H. Chen (araliaceae): Structures of new saponins, notoginsenosides-R1 and -R2, and identification of ginsenosides-Rg2 and -Rh1.

Abstract

From Sanchi-Ginseng, roots of Panax notoginseng cultivated in Yunnan, China, two new dammarane-saponins named notoginsenosides-R1 (5) and -R2 (7S) were isolated by means of reverse phase high performance liquid chromatography. The structures of these saponins were established as 20 (S)-protopanaxatriol 6-[O-β-D-xylopyranosyl-(1→2)-β-D-glucopyranosyl]-20-O-β-D-glucopyranoside (5) and 20 (S)-protopanaxatriol 6-O-β-D-xylopyranosyl (1→2)-β-D-glucopyranoside (7S), respectively, mainly by 13C NMR spectroscopy and mass spectrometry. In connection with this study, assignments of carbon signals of ginsenoside-Rf (11), a minor saponin of Ginseng roots, were substantiated by the application of selective deuteration of the sugar moiety as reported by Stuart et al. Besides these saponins, two known saponins, ginsenosides-Rh1 (12) and -Rg2 (13) which have previously been isolated from Ginseng roots, were also isolated and identified.