Structure of the oligosaccharides isolated from Prosopis juliflora (Sw.) DC. seed polysaccharide

•Partial hydrolysis of polysaccharide furnished three oligosaccharides.•Hydrolysis followed by GLC analysis furnished d-galactose and d-mannose.•Further studies indicated (1→4) mannose units linked to (1→6) galactose units. A water soluble polysaccharide isolated from Prosopis juliflora seed was purified and major homogenous fraction obtained by GPC. Complete hydrolysis of the polysaccharide followed by paper chromatography and GLC analysis indicated the presence of d-galactose and d-mannose in the ratio 1:1.10, respectively. Partial hydrolysis of the polysaccharide furnished one hepta-(I), one octa-(II) and nona-(III) saccharides. Hydrolysis of oligosaccharide I, II and III followed by GLC analysis furnished d-galactose and d-mannose in the ratio 3:4, 3:5 and 5:4, respectively. Methylation analysis, periodate oxidation and 1H NMR spectral studies of oligosaccharides indicated the presence of (1→4) mannose units linked to (1→6) galactose units.