The endosperm of leguminous seeds is usually mucilaginous, and galactomannan is its main component. The seed polysaccharide of Cassia migera (N.O. Leguminosae).
selected for structural investigations, contains 60% of endosperm.
RESULTS AND DISCUSSION
Galactomannan was isolated from the endosperm of Cassia renigera seed by extraction with cold water and precipitation with ethanol. Galactomannan "A", the subject of the present study, was recovered as an acid-soluble, major fraction from the barium complex',2 of the polysaccharide. It was considered homogeneous because (i) almost all of it precipitated from aqueous solution over a narrow concentration-range of ethanol, (ii) the precipitated material obtained from its acetyl derivative displayed the same physical properties and had the same sugar ratio as the original pure polysaccharide, and (iii) a single spot was observed in electrophoresis.
Complete acid hydrolysis of the purified
polysaccharide "A" afforded Dgalactose, D-mannose, and xylose in the molar ratio of 1:2.6:0.07. Methylation analysis of polysaccharide "A" afforded 2,3,6-tri-O-methyl-Dmannose (3.2 mol), 2.3-di-0-methyl-D-mannose (2 mol). and 2,3,4,6-tetra-Omethyl-D-galactose (2.12 mol), together with traces of 2,3,4,6-tetra-O-methyl-Dmannose in the main fraction of the hydrolyzate. The tetra-0-methyl-D-galactose indicates a terminal, non-reducing D-gaiactopyranosyl group. As 2,3,6-tri-O-methyl-D-mannose is a major component, the main chain must be composed of (l&+4)-linked D-mannopyranose residues. Identification of 2,3-di-0-methyl-D-mannose suggests branching at either O-4 or O-6 of the main chain. Traces of tetra-O-methyl-D-mannose indicate that some mannose groups also occupy terminal, nonreducing positions.