Fabaceae POLYSACCHARIDES. III. GALACTOMANNAN FROM Astragalus cicer SEEDS

Seeds of Astragalus cicer L. (Fabaceae) afforded a galactomannan (5.90% yield of seed mass) of molecular weight 1064 kDa, solutions of which had high viscosity [eta] 925.5 mL/g and optical activity [alpha](D) + 71.9 degrees. The galactomannan consisted of galactose and mannose units in a 1:1.39 ratio. Physicochemical methods established that the main chain of the polysaccharide consisted of 1,4-beta-D-mannopyranose units substituted at 72% of the C-6 positions by single alpha-D-galactopyranose units. The content of variously substituted galactose mannobiose units Man-Man, (Gal) Man-Man/Man-Man(Gal) and (Gal) Man-Man(Gal) in the galactomannan were 18.7, 19.8, and 61.5%, respectively.