Preparation and antioxidant properties of low molecular holothurian glycosaminoglycans by HO/ascorbic acid degradation.

An effective method of free radical degradation induced by HO/ascorbic acid, which was different from previously reported HO/Cu method, was developed to depolymerize a novel glycosaminoglycan from Holothuria mexicana (HmG). The results indicated that the degradation efficiency increased with the reduced solution concentration, increased HO concentration and ascorbic acid concentration. The chemical composition and structure of different molecular HmG were analyzed. The results showed that the primary structure and sulfate esters were well reserved during the degradation. Two dimension nuclear magnetic resonance of a low molecular product (DHmG-2) indicate that it contained chondroitin sulfate backbone and major 4-O-sulfated fucose branches. The antioxidant assays of HmG and DHmG-3 showed a fine scavenging abilities on 1,1-diphenyl-2-picrylhydrazyl (DPPH), superoxide and hydroxyl radicals in concentration dependent manner. Besides, molecular weight did not obviously affect the antioxidant activities of HmG.