Carbohydrate structures of three new saponins from the root bark of Hovenia dulcis(Rhamnaceae)

Abstract

The carbohydrate sequences of two major saponins, hovenosides D (1) and G (2) and a minor saponin, hovenoside I (3), obtained from the root barks of Hovenia dulsis Thunb (Rhamnaceae), have been determined mainly by g.l.c.–mass spectrometry, and the full molecular structures of these saponins have been assigned as 3-O-[(2-O-β-D-xylopyranosyl)-3-O-(2-O-β-D-xylopyranosyl-6-O-β-D-glucopyranosyl-β-D-glucopyranosyl)-α-L-arabinopyranosyl]- jujubogenin, 3-O-[(2-O-β-D-xylopyranosyl)-3-O-(2-O-β-D-xylopyranosyl-β-D-glucopyranosyl)-α-L-arabinopyranosyl]jujubogenin, and 3-O-[(2-O-β-D-xylopyranosyl)-3-O-β-D-glucopyranosyl-α-L-arabinopyranosyl]jujubogenin respectively from additional chemical and spectroscopic evidence. Correlations among these saponins have been obtained by the action of enzymes.