Characterization and antioxidant activities of degraded polysaccharides from two marine Chrysophyta

Water-soluble polysaccharides from Pavlova viridis and Sarcinochrysis marina Geitler (P0 and S0, respectively) and their degradation fragments (P1, P2, S1, S2 and S3) were screened for their antioxidant activity using 1,1-diphenyl-2-picrylhydrazyl (DPPH), hydroxyl-radical (OH) scavenging, lipid peroxidation (LPO) inhibition and the mouse red blood cells (RBCs) hemolysis assay. The physicochemical properties of the polysaccharides were also determined. Chemical analysis showed the presence of sulfate groups and uronic acids. Degradation increased the sulfate group content, but also, in part, damaged the uronic acids. FTIR spectroscopy showed that P0 and S0 had β-pyranose and α-pyranose configurations, respectively. The low molecular weight fragments after degradation exhibited higher antioxidant capacities, of which P2 and S3 showed the strongest antioxidant activity in the given assay system. The half-maximal inhibitory concentration (IC50) values of P2 on DPPH, OH, LPO and RBCs hemolysis assays were 0.45, 0.42, 0.88, and 1.51 mg/ml, respectively, and the corresponding IC50 values of S3 were 0.41, 0.41, 0.79, and 1.04 mg/ml, respectively. All the polysaccharide fragments evoked a significant dose dependent inhibitory effect or scavenging ability. Altogether, these results suggest that the polysaccharide of two marine Chrysophyta could be considered as a potential antioxidant.