Preparation, characteristics, and antioxidant activities of carboxymethylated polysaccharides from blackcurrant fruits.

In the present study, the native polysaccharide (RNP) extracted from blackcurrant fruits was carboxymethylated. Physicochemical characteristics and antioxidant activities in vitro of RNP and three carboxymethylated polysaccharides (CRNPs) were determined. GC analysis proved that RNP and CRNPs were composed of the same six monosaccharides (galacturonic acid, rhamnose, arabinose, mannose, glucose and galactose), but the molar ratios of monosaccharides were different. HPLC demonstrated that the molecular weights of CRNPs were improved. The assays of the antioxidant properties indicated that CRNPs possessed stronger scavenging activities on radicals (hydroxyl and superoxide radicals) and better anti-lipid peroxidation activities, as well as better protection effects on erythrocyte hemolyses in vitro compared with RNP. The activities of CRNPs were significantly enhanced with the increase of the degree of substitution (DS). These results proved that the carboxymethylation could effectively increase the antioxidant activities of the polysaccharide.