In vitro antioxidant effects and cytotoxicity of polysaccharides extracted from Laminaria japonica

A water-soluble crude polysaccharide (WPS) was obtained from Laminaria japonica by hot water extraction. Three major polysaccharide fractions (WPS-1, WPS-2 and WPS-3) were purified from WPS by anion-exchange chromatography. Monosaccharide components analysis indicated that galactose was the predominant monosaccharide in WPS and WPS-3, accounting for 56.25% and 54.11%, respectively. And fucose was the predominant monosaccharide in WPS-1 and WPS-2, accounting for 46.91% and 45.1%, respectively. Antioxidant activity tests revealed that WPS-2 showed significant function of scavenging hydroxyl free radical and WPS-1 exhibited the highest inhibitory effects on superoxide radical. Cytotoxicity of all polysaccharide fractions was evaluated by MTT assay and Hoechst 33258 staining. Results showed that WPS-1 and WPS-2 significantly inhibited the growth of A375 cells and low anti-proliferative effects of WPS-2 on vascular smooth muscle cells (VSMCs) were observed. These results suggested that the polysaccharide fraction of WPS-2 might be explored as a potential safe antioxidant and antitumor agent.