LAUSR

The crude polysaccharide (TASP3) was extracted from the fruit pulp of Annona squamosa and then isolated and purified by the combination of grading-alcoholic precipitation and Sephadex G-200. The structure of purified polysaccharide (GASP3-3-I) was determined based on the physicochemical and instrumental analyses. The results indicated that GASP3-3-I was an acidic heteropolysaccharide and its average molecular weight was 2.28×106Da. The monosaccharide composition was analysed by GC-MS and ion chromatography, respectively. It was revealed that GASP3-3-I was consisted of rhamnose, arabinose, xylose, mannose, glucose, galactose, glucuronic acid and galacturonic acid with a molar ratio of 5.06:45.5:5.26:0.63:6.09:31.76:0.49:5.19. Moreover, periodate oxidation reaction, Smith degrading reaction, methylation, FT-IR and NMR were used to conduct the structural characterization of GASP3-3-I. The results indicated that glycosyl residues of GASP3-3-I were mainly composed of (1→) l-arabinose, (1→6), (1→3) and (1,3→6) d-galactose, (1→) d-xylose, (3→) and (3→6) d-glucose, (1→2) l-rhamnose. The α-glucosidase inhibitory activity assay showed that GASP3-3-I had a certain inhibition on α-glucosidase activity.