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.

Abstract

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-β-D-glucopyranosyl(1→2)-β-D-glucopyranosyl]-20-O-(β-D-glucopyranosyl) 20(S)-protopanaxadiol (quinquenoside I), 3-O-[6-O-(E)-2-octenoyl-β-D-glucopyranosyl(1→2)-β-D-glucopyranosyl]-20-O-[β-D-glucopyranosyl(1→6)-β-D-glucopyranosyl]20(S)-protopanaxadiol (quinquenoside II), 3-O-[β-D-glucopyranosyl(1→2)-6-O-acetyl-β-D-glucopyranosyl]-20-O-(β-D-glucopyranosyl) 20(S)-protopanaxadiol (quinquenoside III), 3-O-[β-D-glucopyranosyl(1→2)-β-D-glucopyranosyl]-20-O-[β-D-glucopyranosyl(1→6)-β-D-glucopyranosyl]-3β, 7β, 20(S)-trihydroxydammar-5, 24-diene (quinoquenoside IV), and 3-O-[β-D-glucopyranosyl(1→2)-β-D-glucopyranosyl]-20-O-[α-D-glucopyranosyl(1→4)-β-D-glucopyranosyl(1→6)-β-D-glucopyranosyl]20(S)-protopanaxadiol (quinquenoside V).