Characterization and antioxidant activities of degraded polysaccharides from two marine Chrysophyta

Water-soluble polysaccharides from Pavlova viridis and Sarcinochrysis marina Geitler (P-0 and S-0, respectively) and their degradation fragments (P-1, P-2, S-1, S-2 and S-3) 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 P-0 and S-0 had beta-pyranose and alpha-pyranose configurations, respectively. The low molecular weight fragments after degradation exhibited higher antioxidant capacities, of which P-2 and S-3 showed the strongest antioxidant activity in the given assay system. The half-maximal inhibitory concentration (IC50) values of P-2 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 S-3 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. (C) 2014 Elsevier Ltd. All rights reserved.