Study On The Purification And Biological Activity Of Spirulina Polysaccharide

Spirulina has been recommended as one of the most excellent human food resources and grain in the future by Food and Agriculture Organization of the United Nations.It has been widely applied in food,feeds and medicine.Spirulina contains a series of bioactive substances,such as polysaccharide,phycocyanin,3-carotene and lutein.However,Due to the low level of deep processing,the main product of domestic SpirulinaisSpirulina powder,indicating that domesticSpirulina has not been fully utilized.With the Spirulina powder as raw material in hand,which was provided by Xin da ze co.Ltd.in Fuqing city,small molecular weight components of pigment(chlorophyll,lutein,and ?-carotene),phycocyanin and crude polysaccharide were obtained by the comprehensive utilization technology of Spirulina.Particularly,Spirulina polysaccharide with high purity was obtained by pH-selective precipitation,membrane separation and ion-exchange.In addition,the antioxidant activity and hypoglycemic activity of purified polysaccharide were studied.Theresults are summarized as follows:1.Establishment of the comprehensive extraction processesfor comprehensive utilization of Spirulina.The crude ?-carotene,lutein,phycocyanin,polysaccharide and chlorophyll were extracted step-by-step.from Spirulina,while the extraction residue was used for feed.The extraction conditons of each constituents were optimized by single factor experiment as follows:1)For ?-carotene,the extraction ratio of 94.8%was obtained by low polar extracting twice with solid-liquid rate of 1:20 at 45 ? and 4h for each time.2)For lutein,the extraction ratio of 96.4%was obtained by medium polar extracting twice with solid-liquid rate of 1:20 at 40 ? and 4h for each time.3)For chlorophyll,the extraction ratio of 98.4%was obtained by high polar extracting with twice solid-liquid rate of 1:15 at 40?for 3.5h for each time.4)For phycocyanin,the extraction ratio of 95.0%was obtained by extracting twice with solid-liquid rate of 1:20 at 30? and 3h for each time.5)For polysaccharide,the extraction ratio of 7.84%and purity of 8.90%was obtained with twice solid-liquid rate of 1:20 at 95? for 6h.2.High purity Spirulina polysaccharid was obtained by separation and purification.Its structure was characterized.The traditional technology of enthanol precipitation was improved.The new techniques of pH-selective precipitation,membrane separation and cation exchange resin column chromatography have been setted up for purification of Spirulina polysaccharidewith the yieldof 1.06%and 96.3%purity.Compared with the traditional technology of hot water extraction,enrichment and enthanol precipitation,the new process is simple and can improve the purity significantly.In additon,it can avoid the use of organic solvents and the energy consumption for concentration.The high pure Spirulina polysaccharid was characterized by GC,IR and 1HNMR.It showed that Spirulina polysaccharid contained L-rhommose,D-arabinose,D-xylose,D-mannose and D-galactose with the mole rate of4.0184:0.7885:0.3813:0.0413:0.0152.Spirulina polysaccharid contains the groups of O-H,C-H,methyl,C-O and C=O.The sugar structure of Spirulina polysaccharid is pyranose ring and the glycosidic bond is a-type or ?-type.3.The experimental results show that Spirulina polysaccharide can significantly reduce the blood sugar level.Their activity is similar to that of positive group.The hypoglycemic effect of the pure Spirulina polysaccharide is higher than that of impure Spirulina polysaccharide.But the effect is not proportional to the content of polysaccharide,indicating that the hypoglycemic effect of crude Spirulina polysaccharide may be caused by the other components.4.The antioxidant activities ofpolysaccharide in vitro were estimated in various test systems,including scavenging of 1,1-diphenyl-2-picryl-hydrazyl(DPPH)radicals,superoxide anion radicals,hydroxyl radicals and reducing power activity.The results show that polysaccharide extracted from Spirulina has strong antioxidant properties in vitro,but the activity is inferiored to positive control Vc.The antioxidant activity of high purity Spirulina polysaccharide isstronger than that of impure Spirulina polysaccharide.It may contain other antioxidant material in crude Spirulina polysaccharide.Polysaccharide extracted from Spirulina Platensiswas administrated orally to normal and alloxan-diabetic mice,the hypoglycemic effect was evaluated and antioxidative activitywas compared by determining malonaldehyde(MDA)contents and superoxide dismutase(SOD),1-glutathione(GSH),catalase(CAT)activities of serum in mice.The result showed that the SOD,CAT and GSH activities were significantly enhanced,and MDA contents were significantly decreased.Spirulina polysaccharide can effectively scavange free radicals,reduce the damage of active oxygen free radical and enhance the antioxidative activity in vivo.