Abstract

Treatment of aqueous extracts of the fruit of Cordia abyssinica, containing 0.25% sodium chloride with three volumes of ethanol produced an acidic polysaccharide with a 2% yield, on a fresh weight basis. Upon precipitation of the polysaccharide with acid, the yield of the polysaccharide decreased to 1.2% and the polymer showed some level of degradation. With protein content between 2.6 and 4.6% for the acid and ethanol precipitates respectively, the polymer contained 0.29% hydroxyproline. Treatment of the ethanol precipitated polysaccharide with pronase E resulted in a decrease in viscosity of polysaccharide solutions and high performance size exclusion (HPSEC) chromatograms of the protease treated samples showed peaks that had slightly shifted to low molecular weight. Uronic acid content, determined using the m-hydroxydiphenyl method was 9%. Some uronic acid residues along the polymer chain were methyl esterified, with the methoxyl content being 38%. With an ash content of 17% the polymer had a mineral ion content of Ca, 0.3%, Mg, 0.3%, Na, 0.2% and K, 4.8%. The optical rotation of a 0.25% solution was -50°.

Key words: Cordia abyssinica, polysaccharide, yield, viscosity, hydroxyproline, protein content.