Plant gums of the Genus Sterculia. Part V. Degradation of carboxyreduced Sterculia urens gum

Abstract

Degradation of periodate-oxidised carboxy-reduced Sterculia urens gum affords a degraded polysaccharide which contains essentially linear chains of alternating 4-O-substituted D-galactopyranose and 2-O-substituted L-rhamnopyranose residues. Oligosaccharides formed on partial acetolysis of carboxy-reduced S. urens gum and/or the degraded polysaccharide include 4-O-L-rhamnopyranosyl-D-galactose, 2-O-D-galactopyranosyl-L-rhamnose, 4-O-D-galactopyranosyl-D-galactose, 2-O-D-galactopyranosyl-D-galactose, O-D-galactopyranosyl-(1 → 2)-O-D-galactopyranosyl-(1 → 4)-D-galactose, and a series of higher oligosaccharides containing galactose and rhamnose residues in alternating sequences. The significance of these and previous results is assessed in terms of two main structural regions (A and B) in the polysaccharide.