Structural analysis of an immunoenhancing heteropolysaccharide isolated from the green (unripe) fruits of Solenum melongena (Brinjal).

A water-soluble polysaccharide (SMPS) isolated from the aqueous extract of the green (unripe) fruits of Solenum melongena (Brinjal) contains D-galactose, D-methyl galacturonate, 3-O-acetyl D-methyl galacturonate, and L-arabinose in a molar proportion of nearly 1:1:1:1. Structural investigation of the polysaccharide was carried out using total acid hydrolysis, methylation analysis, periodate oxidation study, and NMR studies ((1)H, (13)C, DQF-COSY, TOCSY, NOESY, ROESY, HMQC, and HMBC). On the basis of the above experiments the structure of the repeating unit of the polysaccharide (SMPS) was established as -->5)-alpha-L-Araf-(1-->4)-beta-D-Galp-(1-->2)-alpha-D-3-O-Ac-GalpA6Me-(1-->2)alpha-D-galpA6Me-(1--> This molecule showed splenocyte and thymocyte activations.