Characterization and antioxidant activity in vitro and in vivo of polysaccharide purified from Rana chensinensis skin

•A polysaccharide fraction RCSP II from Rana chensinensis skin was characterized.•RCSP II has a higher antioxidant activity on ABTS radicals and chelate ferrous ion.•RCSP II showed good antioxidant activity in livers and serums of aging mice.•RCSP II can be explored as novel natural antioxidant or functional food.

Preliminary characterization and antioxidant activity in vitro and in vivo investigation of the polysaccharide fraction named as RCSP II, which was extracted from Rana chensinensis skin, were performed. Results indicated that RCSP II comprised glucose, galactose, and mannose in a molar ratio of 87.82:2.77:1.54 with a molecular weight of 12.8 kDa. Antioxidant activity assay in vitro showed that RCSP II exhibited 75.2% scavenging activity against 2,2′-azino-bis(3-ethylbenz-thiazoline-6-sulfonic acid) radicals at the concentration of 2500 mg/L and 85.1% against chelated ferrous ion at 4000 mg/L. Antioxidant activity assay in vivo further showed that RCSP II increased the activities of antioxidant enzymes, decreased the levels of malondialodehyde, and enhanced total antioxidant capabilities in livers and sera of d-galactose induced mice. These results suggested that RCSP II could have potential antioxidant applications as medicine or functional food.