[Composition and structure of galactomannan from the seed of Gleditsia ferox Desf].

Galactomannan, a heteropolysaccharide with a molecular weight of 1660 kDa, was isolated form the seed of Gleditsia ferox Desf., introduced in Russia, with a yield of 18.9%. Its aqueous solutions were optically active ([alpha]D = +30.5 degrees) and highly viscous ([eta] = 1430 ml/g). Analysis of the heteropolysaccharide using chemical, enzymatic, and chromatographic procedures showed that it consists of D-mannopyranose and D-galactopyranose residues (molar ratio, 2.54:1). The main chain of this galactomannan consists of 1,4-beta-D-mannopyranose residues, 39.2% of which are substituted at C6 with single residues of alpha-D-galactopyranose. The probability of occurrence of mannobiose units differentially substituted with galactose was determined by 13C-NMR data and equaled, respectively, 0.37, 0.47, and 0.16 for non-substituted Man-Man units, monosubstituted Gal(Man-Man) and (Man-Man)Gal units taken together, and for the disubstituted Gal(Man-Man)Gal units.