Pumpkin polysaccharides: Purification, characterization and hypoglycemic potential

The separation and purification of pumpkin polysaccharide by aqueous two-phase system combined with DEAE cellulose-52 column chromatography. There are two purified polysaccharides, neutral fractions (ATPS-PP-1) (7.67 kDa) and acidic fractions (ATPS-PP-2) (8.83 kDa), were obtained from pumpkin powder which were subsequently characterized structurally. The backbone of ATPS-PP-1 comprised of (1 → 3)-linked-Glcp having branching points at O-3 of (1 → 3,4)-linked-Glcp with terminal Glcp as side chain. ATPS-PP-2, on the other hand, comprised of 1 → Glcp, (1 → 3)-linked-Galp, (1 → 6)-linked-Glcp, (1 → 3,6)-linked-Glcp and (1 → 4)-linked-Glcp as backbone. And ATPS-PP-1with small molecular weight and the backbone consisted of (1 → 3) glycosidic linkages has better hypoglycemic activity. Significant protection was conferred on streptozotocin damaged islet β cells by ATPS-PPs (neutral fractions and acidic fractions). Such protective effect was demonstrated by ATPS-PPs' ability to lower Nitric oxide levels by inhibiting NF-κB mRNA overexpression and afterwards down regulation iNOS mRNA expression, eventually minimizing cell oxidative damage caused by STZ and restoring the normal levels of superoxide dismutase.