In this study, the structural characterization of Sphallerocarpus gracilis polysaccharide (SGP) and its hypoglycaemic activities are reported for the first time. SGP, which has a weight average molar mass (Mw) of 7.413×105, was isolated from Sphallerocarpus gracilis and purified by ion-exchange chromatography. The polysaccharide is composed of rhamnose, arabinose, mannose, glucose and galactose, with the molar ratio of 4.12: 8.99: 5.45: 65.94: 15.50. The mechanism underlying the hypoglycaemic effect of SGP was evaluated. Experimental results showed that SGP protected pancreatic β-cells from alloxan damage by several possible mechanisms, including: (1) repairing free radical damage; (2) reducing the apoptosis of pancreatic β-cells by inhibiting the activities of caspase-3 and bax, and enhancing the activity of bcl-2; (3) stimulating insulin secretion and upregulating the pancreatic and duodenal homeobox 1 gene and the insulin gene and the pancreatic in pancreatic β-cells. The results obtained in this study suggest that SGP may be a promising therapeutic agent in the treatment of diabetes mellitus.
Keywords: Anti-apoptotic; Insulin secretagogue actions; Pancreatic β-cells; Sphallerocarpus gracilis polysaccharide.
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