STRUCTURAL INVESTIGATION OF PROSOPIS-CINERARIA (KHEZRI) SEED GALACTOMANNAN

Purified polysaccharide isolated from the seeds of Prosopis cineraria contains. D-galactose and D-mannose in a molar ratio of 1:4.65. Homoge neity of the polysaccharide has been checked by exclusion chromatograp hy and ultracentrifugal analysis. Sedimentation constant of the polysa ccharide is found to be 1.65 corresponding to a molecular weight of 2. 6 x 10(4). Partial hydrolysis of the polysaccharide furnishes a tri-, a tetra- and a penta-saccharide alongwith a degraded polysaccharide. S tructures of the oligosaccharides and degraded polysaccharide have bee n established by methylation studies. Methylation analysis of the poly saccharide has shown that backbone is composed of (1-->4) linked beta- D-mannopyranosyl units, to which are attached as side chains, alpha-D- galactopyranosyl (as a single unit or three units) and beta-D-mannopyr anosyl (as a single unit) residues by (1-->6) linkages. The proposed s tructure of galactomannan has been supported by periodate oxidation an d Smith degradation studies. The anomeric configurations of monosaccha rides in the polysaccharide have been determined by PM R, C-13 NMR and IR data and by chromium trioxide oxidation studies.