Evaluation of antioxidant activity of the polysaccharides extracted from Lycium barbarum fruits in vitro

Polysaccharides, one of the most important functional constituent in Lycium barbarum fruits, a famous Chinese medicinal herb, are isolated with boiling water decoction. Analysis shows that its carbohydrate content is up to 97.54% mainly composed of d-rhamnose, d-xylose, d-arabinose, d-fucose, d-glucose, and d-galactosc. In the present study, the antioxidant activity of the polysaccharides extracted from L. barbarum fruits was evaluated by six established in vitro methods, namely superoxide radical (image) scavenging activity, reducing power, β-carotene–linoleate model, inhibition of mice erythrocyte hemolysis mediated by peroxyl free radicals, 1,1-diphenyl-2 picrylhydrazyl (DPPH−) radical-scavenging and metal chelating activity. The polysaccharides showed notable inhibitory activity in the β-carotene–linoleate model system in a concentration-dependent manner. Furthermore, it exhibited a moderate concentration-dependent inhibition of the DPPH− radical. The multiple antioxidant activity of the polysaccharides was evident as it showed significant reducing power, superoxide scavenging ability, inhibition of mice erythrocyte hemolysis mediated by peroxyl free radicals and also ferrous ion chelating potency. The data obtained in the in vitro models clearly establish the antioxidant potency of the polysaccharides extracted from L. barbarum fruits.