Acylated protopanaxadiol-type ginsenosides from the root of Panax ginseng

Six new protopanaxadiol-type ginsenosides, named ginsenosides Ra ₄-Ra ₉ (1-6, resp.), along with 14 known dammarane-type triterpene saponins, were isolated from the root of Panax ginseng, one of the most important Chinese medicinal herbs. The structures of the new compounds were determined by spectroscopic methods, including 1D- and 2D-NMR, HR-MS, and chemical transformation as (20S)- 3-O-{β-D-6-O-[(E)-but-2-enoyl] glucopyranosyl-(1→2)-β-D-glucopyranosyl}-20-O-[β-D-xylopyranosyl- (1→4)-α-L-arabinopyranosyl-(1→6)-β-D-glucopyranosyl] protopanaxadiol (1), (20S)-3-O-[β-D-6-O-acetylglucopyranosyl-(1→2)- β-D-glucopyranosyl]-20-O-[β-D-xylopyranosyl-(1→4) -α-L-arabinopyranosyl-(1→6)-β-D-glucopyranosyl]protopanaxadiol (2), (20S)-3-O-{β-D-6-O-[(E)-but-2-enoyl]glucopyranosyl-(1→2)-β- D-glucopyranosyl}-20-O-[β-D-glucopyranosyl-(1→6)-β-D- glucopyranosyl]protopanaxadiol (3), (20S)-3-O-{β-D-6-O-[(E)-but-2-enoyl] glucopyranosyl-(1→2)-β-D-glucopyranosyl}-20-O-[α-L- arabinopyranosyl-(1→6)-β-D-glucopyranosyl]protopanaxadiol (4), (20S)-3-O-{β-D-4-O-[(E)-but-2-enoyl]glucopyranosyl-(1→2) -β-D-glucopyranosyl}-20-O-[α-L-arabinofuranosyl-(1→6) -β-D-glucopyranosyl]protopanaxadiol (5), (20S)-3-O-{β-D-6-O-[(E)-but- 2-enoyl]glucopyranosyl-(1→2)-β-D-glucopyranosyl}-20-O-[α-L- arabinofuranosyl-(1→6)-β-D-glucopyranosyl]protopanaxadiol (6). The sugar moiety at C(3) of the aglycone of each new ginsenoside is butenoylated or acetylated.