Bioactive saponins and glycosides. XI. Structures of new dammarane-type triterpene oligoglycosides, quinquenosides I, II, III, IV, and V, from American ginseng, the roots of Panax quinquefolium L.

The methanolic extract and 1-butanol-soluble fraction of American ginseng, the roots of Panax quinquefolium L., were found to exhibit a protective effect on liver injury induced by D-galactosamine and lipopolysaccharide. Five new dammarane-type triterpene oligoglycosides called quinquenosides I, II, III, IV, and V were isolated together with fourteen known dammarane-type triterpene oligoglycosides such as chikusetsusaponin IVa, pseudo-ginsenoside-RC1, malonyl-ginsenoside-Rb1, and notoginsenosides-A,-C, and -K from the 1-butanol-soluble fraction. From the ethyl acetate-soluble fraction, four known acetylenic compounds and 6'-O-acetyl ginsenoside-Rg1 were isolated. The structures of quinquenosides I, II, III, IV, and V were determined on the basis of chemical and physicochemical evidence as 3-O-[6-O-(E)-2-butenoyl-beta-D-glucopyranosyl(1-->2)-beta-D- glucopyranosyl]-20-O-(beta-D-glucopyranosyl) 20(S)-protopanaxadiol (quinquenoside I), 3-O-[6-O-(E)-2-octenoyl-beta-D- glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-20-O-[beta-D-glucopyranosyl (1-->6)-beta-D-glucopyranosyl] 20(S)-protopanaxadiol (quinquenoside II), 3-O-[beta-D-glucopyranosyl (1-->2)-6-O-acetyl-beta-D-glucopyranosyl]-20-O-(beta-D-glucopyranosyl) 20(S)-protopanaxadiol (quinquenoside III), 3-O-[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-20-O-beta-D- glucopyranosyl(1-->6)-beta-D-glucopyranosyl]-3 beta, 7 beta, 20(S)-trihydroxydammar-5,24-diene (quinquenoside IV), and 3-O-[beta-D-glucopyranosyl(1-->2)-beta-D-glucopyranosyl]-20-O-[alpha-D- glucopyranosyl(1-->4)-beta-D-glucopyranosyl(1-->6)-beta-D-glucopyranosyl ] 20(S)-protopanaxadiol (quinquenoside V).