A polysaccharide was isolated from the broth of cultured Streptomyces virginia H03 which was treated by ethanol deposition and savage method to remove the protein, and was purified using Sephadex G-150 column chromatography. The components of the polysaccharide were determined by gas chromatography. The purified polysaccharide was made up of mannose, glucose and galactose, in a 2:1:1 proportion. Its average apparent molecular weight was 3.76 · 104 Da which was determined by gel permeation chromatography. In addition, several antioxidant assays were adopted to investigate the antioxidant activity of the polysaccharide in vitro. The results indicated that the purified polysaccharide showed significant antioxidant activity against superoxide anion, hydrogen peroxide and 1,1-diphenyl-2-picrylhydrazyl radical, and lipid peroxidation as with standard antioxidants such as vitamin C. Furthermore, the polysaccharide had a better heat stability than vitamin C, which suggested that the polysaccharide might be a potent useful antioxidant
Emulsifying properties and antioxidant activity of soy protein isolate conjugated with tea polyphenol extracts
