Abstract: Objective: To determine the content of total polysaccharides (LBP) and uronic acid from wild Lycium barbarum, as well as their in vitro antioxidant activities. Methods: phenol-sulfuric acid and sulfuric acid-carbazole method were used to evaluate the total contents of LBP and uronic acid, respectively. LBP structural composition was detected by IR spectra. DPPH, superoxide anion radicals, hydroxyl radical scavenging and reducing power of LBP were analyzed for antioxidant activity in vitro, with VC as control. Results: The polysaccharides and uronic acid content was 58.31% and 32.17%, respectively, in the extract of wild plants. At 1 mg/mL of polysaccharide, the DPPH, superoxide radical and hydroxyl radicals-scavenging activities was 81.30%, 50.33% and 60.57%, respectively, while the reducing power was slightly lower than that of VC. These results suggested that polysaccharides in extract from wild plants show potent antioxidant activities, which might provide a scientific basis for further exploitation and the significance of protecting Lycium barbarum in north Shaanxi province.

Key words: north Shaanxi province, Lycium barbarum, polysaccharide, free radical, antioxidant activity in vitro