Antioxidant activity of xanthan oligosaccharides prepared by different degradation methods

Two kinds of water soluble xanthan oligosaccharides (XGOS-A and XGOS-B) with similar molecular weights were prepared by oxidative degradation of xanthan gum (XG) under acidic and alkaline condition, respectively. Antioxidant activity of XGOS-A and XGOS-B was evaluated by the scavenging of superoxide anion radical ((·)O(2)(-)), hydroxyl radical (OH), 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, hydrogen peroxide (H(2)O(2)), determination of ferrous ion chelating activity and reducing power. All the above antioxidant evaluation indicated that XGOS-A and XGOS-B exhibited good antioxidant activity in a concentration-dependent manner. The XGOS-B exhibited better antioxidant activity than XGOS-A. These results may be related to the different structure properties of XGOS-A and XGOS-B especially the different contents of pyruvate acid and reducing sugar.