Chemical analysis and antioxidant activities in vitro of polysaccharide extracted from Opuntia ficus indica Mill. cultivated in China

The polysaccharideof Opuntia ficusindica Mill. was isolated by water, and purified by Sephacryl S-400 HR column. The purity of polysaccharidewas evaluated by HPLC coupled with gel permeation chromatography. Results showed that the neutral monosaccharidecomposition of O. ficusindica polysaccharidewas rhamnose, arabinose, and glucose in a molar ratio of 1.00:2.98:2.57, with an average molecular weight of about 172,591 Da. Further, its antioxidant capacities in vitro were respectively evaluated by the assays of inhibition of pyrogallol autoxidation, scavenging hydroxyl radical, and liver lipid peroxidationinhibiting. The crude water-soluble polysaccharideand purified polysaccharideshowed notable free radical scavenging activity and hydroxyl radical-induced liver lipid peroxidationinhibiting ability, suggesting that O. ficusindica polysaccharidemay be considered as a potential candidate for the natural antioxidants and possible health-promoting functional foods.