Chemical Characterization and Antioxidant Activities of Different Sulfate Content of λ-Carrageenan Fractions from Edible Red Seaweed Chondrus ocellatus
In recent years, sulfated polysaccharides from marine algae have been demonstrated to have many activities including antioxidant activities. But whether degraded sulfated polysaccharides from Chondrus ocellatus have antioxidant activities, and what effects their sulfate content may have on those activities has not been reported. The aim of this study is to explore the antioxidant activities of λ-carrageenan fractions from edible red seaweed Chondrus ocellatus. In the present study, λ-carrageenan from Chondrus ocellatus was degraded by microwave, yielding five products of different molecular weights. Three sulfated polysaccharide fractions (CF1, CF2, and CF3) were isolated from one of the degraded λ-carrageenans (PC2) by anion-exchange column chromatography. In this study, the effects of the three polysaccharide fractions on hydroxyl radicals, superoxide radicals, organic free radical DPPH, H2O2 induced hemolysis of rat erythrocytes and lipid peroxidation in rat liver microsome were investigated. The
results indicated that IR spectrum results indicated that these sulfated polysaccharide fractions had similar structures, but differed in their sulfate content. Chemical analysis indicated that CF1 had the lowest sulfate content (2.9%), while sulfate content in CF2 and CF3 was 7.8% and 37.5% respectively. CF3 had stronger scavenging activity on superoxide radical and hydroxyl radical than the other fractions (P<0.05). CF3 had the strongest scavenging activity on DPPH. the highest inhibitor of lipid peroxidation was CF3, with an IC50 of 0.087 mg/mL, and inhibitory rate reaching 90% at 1 mg/mL. All of the three fractions exhibited stronger scavenging activity at high concentration. In conclusion, sulfate group content of polysaccharides also effect on their biological activities, and which is important for antioxidant activities.