Studies on uronic acid materials and structure of Acacia decurrens gum polysaccharide

The polysaccharide exuded by Acacia decurrens trees contains residues of D-galactose , LArabinose , L-Fucose and Dglucuronic acid. An examination of the OMethyl derivatives of the gum yields 2,3,4,6 tetra –O-methyl –D-galactose, 2,3 –di-O-Methyl –L-arabinose , 2,3,4-triO-methyl-D-galactose, 2,4-di-O-methyl-D-galactose together with 2,3,4 tri-O-methyl-Dglucuronic acid by acid hydrolysis. The degraded gum obtained after controlled acid hydrolysis is examined by linkage and methylation analysis. The O-methyl derivatives of the degraded gum yields; 2,3,4,tri-O-methyl-D-glucuronic acid, 2,4,6,tri-O-methyl-D-galactose, 2,3,4tri-O-methylD-galactose and 2,4 –di-O-methyl-D-galactose. These are examined by linkage and methylation analysis. The structural evidences suggests that Acacia decurrens gum molecules possess highly branched galactose framework to which D-glucuronic acid and residues of L-arabofuranose are attached , this conclusion is further supported by the methylation study of the Acacia gum.