Study On Purification And Biological Activities Of The Laminaria Japonica Polysaccharides

Laminaria japonica, a member of brown alga, is the most important economic seaweed cultured in China. Moreover, some areas in Fujian province, such as Xiapu, Lianjiang and Putian, abounded with Laminaria japonica. In traditional Chinese medicine, it has been documented as a drug for over a thousand years. Over the past decades, Laminaria japonica has drawn the attention of chemists and pharmacologists on account of the abundance of functional compounds and their biological activities. Among these compounds, polysaccharides have been considered as the main active components, which appear to elicit excellent functions in the prevention of diseases, including antioxidant, anticoagulant, anti-atherosclerosis and immunoregulation. In the paper, based on abundant alga resource in Fujian province, bioactive polysaccharides of Laminaria japonica were investigated, including purification and components of Laminaria japonica polysaccharides. The biological activities of Laminaria japonica polysaccharides were assessed.A water-soluble crude polysaccharide (WPS) was obtained from Laminaria japonica by water extraction and ethanol precipitation with a yield rate of 2.5%. The crude polysaccharide of WPS was further purified by anion-exchange to obtain fraction of WPS-1. It was further purified by Gel penetration chromatography to obtain purified fractions of WPS-1-2. The results of high performance liquid chromatography and agarosegel electrophoresis indicated that the purified fraction of WPS-1-2 was homogenous polysaccharides with a molecular weight of 282 KDa. It was sulflated polysaccharide with sugar content of 92.3% and 10.4% sulfate. The results of RP-HPLC analysis showed that the purified fraction of WPS-1-2 was mainly composed of fucose, galactose and fucose with a molar ratio of 3.97:3.83:1.Biological activity tests in vitro revealed that purified fraction of WPS-1-2 exhibited significant anoxidant activity. Compared to crude polysaccharide of WPS, the purified fraction of WPS-1-2 improved two times antioxidant capacity. Furthermore, the purified fraction of WPS-1-2 showed significant scavenging effects on superoxide and hydroxyl radicals. At the concentration of 1 mg/mL, the scavenging ratio of WPS-1-2 on superoxide anion radical was 95%, as much as the scavenging ration of Vitamin C. At the concentration of 3 mg/mL, the scavenging ratio of WPS-1-2 on hydroxyl radical was 93%, higher than that of Vtamin C.The H2O2-induced proliferation of vascular smooth muscle cells was observed. In vitro, the purified fraction of WPS-1-2 could significantly inhibited cells growth with a dose-dependent manner. The highest inhibitory ratio was 73%. The results of cell morphology indicated that the purified fraction of WPS-1-2 could induce cells apoptosis. Further investigations demonstrated that the hydrolytic gelatin activities of MMP2 and the levels of MDA was decreased with the increase of the concentrations of WPS-1-2. The inhibitory activities on cells would be related with apoptotic effects and scavenging activities of WPS-1-2.