Separation、Structure Identification And Biological Activities Of Fucoidin From Guangdong Laminaries Japonica

Laminaries japonica fucoidin, also known as Fucoidan, consists a number ofL-fucoses with sulphate radicals. Fucoidan has many bioactivities, such as anti-virus,anticoagulant, killing tumor cells and adjusting immune function. Laminaria japonicafucoidin is a sulphated polysaccharide, and its structure is very complex and differentfrom each other with its origin, growing in various seasons, and different tissues, andtreatment methods, which leads to a lot of troubles in puzzling results from differentgroups.Objective: We seeked the conditions of extraction and purification, and testedantioxidant activity of fucoidan from Laminaria japonica in Southern China sea. Inorder to provide primary dates on developing medicament and food based on fucoidanextracted from Laminaria japonica in Southern China sea.Methods: Diluted hydyochloric acid and microwave-assisted extractiontechnology were used to investigate the extraction technology of the fucoidan fromLaminarie japonica. The orthogonal test was practised in seeking the optimalextraction conditions. The effect of competitive chelators, EDTA and diatomaceousearth on depriving heavy metals binding with fucoidan was checked. The purificationof main component in crude fucoidan（LJF）﹑LJF-2was proved by chromatography ofSephadexG-200﹑HPLC and polarimetry respectively. The structure of LJF-2wascharacterized with UV﹑FT-IR﹑XRD and Congo red test. Antioxidant activity andthe reducing ability and protective effects of LJF and LJF-2on H₂O₂inducinghemolysis of erythrocytes were measured by the in vitro system.Results: The optimal process condition for diluted hydyochloric acid extraction ofthe fucoidan from Laminaria japonica was pH value being4and treating time being5h，and the extraction temperature being60℃, and the extracting ratio of crudefucoidan was4.85%. For microwave-assisted extraction was extraction time being20min, microwave power with560W and extraction times being4times. And theextracting ratio was5.46%. The removal ratios of Cd, and Fe ions by EDTA were71.78%and66.78%respectively, which was significantly higher than those by diatomaceous earth. The purity of LJF-2was identified by chromatography ofSephadexG-200, HPLC and polarimetry respectively. Results showed that LJF-2waspurific without proteins, peptides and other polysaccharides. The FT-IR result provedthat LJF-2had a characteristic absorption peak of polysaccharide containing sulfateand uronic acid. The result of XRD showed that LJF-2was non crystal. The Congored test showed the space conformation of LJF-2in aqueous solution was non-rulecurly instead of triple helix as polysaccharides usually do. The results of antioxidantsshowed that LJF and LJF-2had certain abilities of scavenging free radicals. Theirscavenging effects showed positive correlation with their concentrations. When theconcentration of polysaccharide was6.0g/L, the scavenging rates of LJF-2on DPPH﹑hydroxyl radicals and superoxide anion radicals were79.30%﹑89.66%﹑79.61%respectively. They were all lower than the scavenging rates of LJF with the sameconcentration. When the concentration of polysaccharide was6.0g/L, the absorbancevalue was0.812, and lower than the same concentrations of the absorbance value ofLJF-2, which ment that the reducing ability of LJF was stronger than that of LJF-2.The protective effects of LJF and LJF-2on H₂O₂induced hemolysis of erythrocytesshowed that LJF was stronger than LJF-2, which was consistent with their antioxidantactivities.In conclusion, the extraction rate of microwave-assisted of fucoidan was thehighest in all extraction processes. The antioxidant activity of crude fucoidan wasstronger than the purified fucoidan. These demonstates present a sophisticated processto find out relations of structures and functions of other components from fucoidan.