Structural studies of an acidic polysaccharide from the seeds of Acacia auriculaeformis A. Cunn

Abstract

An acidic polysaccharide isolated from the defatted seeds of Acacia auriculaeformis contained l-arabinose, d-xylose, d-galactose, d-glucose, and d-glucuronic acid in the molar ratios 1.5:2:2.2:1:3. Autohydrolysis of an aqueous solution of the polysaccharide yielded an electrophoretically homogeneous, degraded polysaccharide consisting of d-xylose, d-galactose, d-glucose, and d-glucuronic acid in the molar ratios 1:3.9:1.9:6.7. Methylation analysis, periodate oxidation, and Smith degradation of the native and degraded polysaccharide and their carboxyl-reduced derivatives indicated that the polysaccharide is branched with 3,6-linked galactosyl and 2,4-linked glucosyl residues at the branch points to which are attached chains comprised of arabinose, xylose, glucose, galactose, and glucuronic acid residues via different linkages. Oxidation of the acetylated polysaccharide with chromium trioxide indicated that most of the glucose and arabinose residues were α, while xylose, galactose, and glucuronic acid were mostly β. A d.p. of ∼89 was established for the polysaccharide by end-group analysis.