Marine Microalgae Polysaccharide Extraction And Purification And Structural Characteristics

Because of the growth conditions and environmental characteristics of marine microalgae, the structure and function of intracellular polysaccharide in marine microalgae are different from those of terraneous polysaccharide, so more and more people are interested in potential application in the field of medicine and medical science. Four kinds of microalgae such as Spirulina Dunaliell Chlorella Platymonas as raw materials were cultured in order to extract intracellular polysaccharide. The specific steps were as follows: first, the cells were crashed by penetrated shaking with frozen-thawn, the water-soluble polysaccharides were extracted from the microalgae biomass with cold water or hot water as extracting agent; second, the raw polysaccharide were obtained by ethanol precipitation after proteins and some small molecules were wiped up from the water-soluble polysaccharides; finally, the pure polysaccharides were obtained by ethanol precipitation and dextran-gelcolumn chromatography. The properties of physical chemistry and the characteristics of components and structures were determined by means of chemical and equipment analysis.The experimental results show that the polysaccharides from different microalgae and from different fractions in the same microalga are similar in the structures and functions. The rings of sugars are pyran rings and there are acetamine and sulfate radicals in the sugar links. For monopolysaccharide glycon, D-glucose and D-galactose are in the majority, while D-fucose, D-rhamnose and D-2-glucosamine are relatively small.The polysaccharides from different microalgae and different fractions in the same microalga also differ in the golycon components and the mole ratio. The Spirulina polysaccharide has six kinds of netural glycons, among them, D-glucose, D-galactose and D-rhamnose have been determined, and their mole ratio are 5.01 '. 63.5 correspondingly. The glucosidic bond is a type. The Dunaliell polysaccharide has seven kinds of netural glycons and various uronic acids. Among them, five kinds of glycons have been determined, they are D-fucose, D-rhamnose , D-2-glucosamine, D-galactose and D-glucose, and their mole ratio are 2.1 : 1.0 : 1.6 : 2.3 ; 4.2. correspondingly; two kinds of uronic acids are determined, they are galacturonic acid and glucuronic acid , and their mole ratio are 1 :3.4. The glucosidic bond is Btype.The Chlorella polysaccharide has seven kinds of netural glycons. Among them, five kinds are the same as the known glycons of Dunaliell polysaccharide, but their corresponding mole ratio are different, they are 1.3 : 1 : 1.4 : 1.2 : 3.1 here.Theglucosidic bonds of both kinds of the Platymonas polysaccharide are Btype. Ten kinds of glycons and uronic acids are included in one of the polysaccharide. Among them, five kinds of glycons are determined, they are D-fucose, D-rhamnose, D-galactosamine, D-galactose and D-glucose, and their mole ratio are 14.1 : 1 : 44.6 : 58.9: 76.7 correspondingly; two kinds of uronic acids are known, they are galacturonic acid and glucuronic acid ,and their mole ratio are 1 : 3.2. The other Platymonas polysaccharide has seven kinds of glycons. Among them,four kinds are determined,they are D-rhamnose,arabinose, D-gluco -samine , D-galactose, and their mole ratio arel: 18.0 : 40.9 : 59.6 correspondingly.The results above provide fundamental information in the components and structures for further studying the function and application of the microalgae polysaccharides.