A non-ionic water soluble seed-gum from Parkinsonia aculeata

A nonionic water-soluble galactomannan, having a galactose and mannose in 1:2.66 molar ratio was isolated from endosperm of the seeds. Acid catalyzed fragmentation, periodate oxidation, methylation and enzymatic hydrolysis showed that seed gum has a branched structure consisting of a linear chain of β (1→4) linked mannopyranosyl units with d-galactose side chains attached through α (1→ 6) linkage to the main chain. Hydrolysis of the fully methylated seed gum gave 2,3,4,6-tetra-O-methyl-d-galactose, 2,3,6-tri-O-methyl-d-mannose and 2,3-Di-O-methyl-d-mannose in 1.00:1.66:1.01 molar ratios. Both the methylation and periodate oxidation studies indicated about 26.5% of the end groups. The significance of these results together with the findings of partial hydrolysis by acid is discussed in relation to ascertaining the structure of the repeating unit of the polysaccharide.