The Extraction,Structural Analysis And Antioxidation Of Fucoidan

In this article, Fucoidans were extracted and purified from the brown seaweed. The physicochemical properties,structure and antioxidant properties in vitro of fucoidan were studied. The results showed as following:(1)Fucoidans were isolated from the brown seaweed by hot water extract method,ultrasonic wave assisted method,microwave assisted method and multienzyme enzymolysis method. The most rational method obtained by contrast was multienzyme enzymolysis method: 10 g brown seaweed powder were soaked with 400 ml water (weight of material: weight of water=1:40), and grined by colloid mill, put in water of 90℃for 1 h as a pretreatment, cool to room temperature, adjust pH value to 3.5 by the buffer solution of phosphate, add multienzyme (1% weight of brown seaweed powder), enzymolysis in water of 30℃for 1.5 h, then temperature warm to 90℃quickly and extract in the temperature for 3 h, intermixture were centrifugated, and the powder were soaked with 400 ml water (weight of material: weight of water=1:40), extracted in water of 90℃for 1 h.(2)During the purification of crude fucoidan, remove the protein in the crude fucoidan by Sevage method. The most optimum elution condition in purification of crude fucoidan using DEAE-Sepharose FF is 0.2 mol/L NaCl for 2 h, 0.4 mol/L NaCl for 2 h, 0.6 mol/L NaCl for 2 h, 0.8 mol/L NaCl for 2 h after eluationg with Tris-HCl (pH=7.0) buffer solution for 20 min. Two fucoidans were collected and their purity were identified by GLC and SDS-PAGE methods. They were named F1 and F2.(3) F1 and F2 both have abilities of reduction and blocking peroxidation of polyunsaturated fatty acid from yolk lipoprotein induced by ferrous ion. And the abilities of F1 are stronger than F2's, the most probable factors are that F1's molecular weight and total sulfate content are more than F2's.(4)During the study of fucoidans' physicochemical properties, molecular weight of F1 and F2 are 120226.4 and 13182.5 respectively, both F1 and F2 are sulfate polysaccharides, even the total sulfate of F1 is 5.6 percent more than F2's. (5) During the study of fucoidans' structure, both F1 and F2 were made up of D-galactose,D-mannose,D-rhamnose,D-xylose,L-fucoidan and L-glucose. Sulfate groups lie to C4 of fucose, and lie to axial position of saccharide ring's hydroxy group.