Selective cleavage of β- d-glucopyranosiduronic acid linkages in methylated polysaccharide acids from Drosera species

Abstract

Permethylated derivatives of the polysaccharide mucins from the leaves of Drosera binata and Drosera capensis have been subjected to the following sequence of reactions: ( i) saponification; ( ii) decarboxylation—acetoxylation with lead tetraacetate; and ( iii) reductive cleavage of the derived 5-acetoxypentopyranosidic linkages with sodium borohydride to give series of 4- O- d-mannopyranosyl- d-xylitol derivatives having side-chain substituents (where present) attached. The oligosaccharide alditols have been separated and characterized to provide evidence for alternating sequences of d-glucuronic acid and d-mannose residues in the main chains, and for the nature and sites of attachment of sugar residues in side chains in both polysaccharides, and, for D. capensis, some evidence for anomeric configurations of glycosidic linkages.