Submerged Fermentation And Extraction,Purification And Antioxidant Activities Of Polysaccharides From Lepista Irina

Lepista irina is a kind of wild mushroom with edible and medicinal functions,as well as important nutritional value and broad application prospects.Up to now,most fruit bodies of the species are collected from the wild,which seriously restricts the production and utilization of Lepista irina.As an important fungal secondary metabolite,polysaccharides have a lot of biological activities besides being widely involved in the life activities of cells.However,the related research about polysaccharides of Lepista irina is limited.The purposes of this research include opimization of submerged fermentation conditions,opitimization of polysaccharide extraction conditions,separation,purification and antioxidant activity,with the mycelia of Lepista irina as experimental materials.The main results are listed as follows.The results of the growth of mycelium and the accumulation of polysaccharide showed that the maximum of mycelial biomass reached the highest on the 8th day and the intracellular polysaccharide content reached the highest on the 9th day.The most optimal conditions of the fermentation:culture temperature is 25?,the p H value is 5.4,the liquid volume is 110 m L,and the mycelial biomass reach 12.86 g·L^-1.The crude polysaccharides from Lepista irina were extracted using hot water.By the method of response surface,analyzing the factors which affect the extraction rate of polysaccharides.The optimum extraction conditions for the polysaccharide were listed as follows:ratio of water to material 43:1,extraction temperature is 86?,extraction time is 1.7h,and the polysaccharide extraction rate reaches 40.95%.Then,the extraction of crude polysaccharides was separated by DEAE-52 cellulose column and eluted by Na Cl gradient,and three components were obtained,i.e.LIP-1,LIP-2and LIP-3.Among them,LIP-1 is neutral polysaccharide and the other two are acidic polysaccharide.The recoveries were 6.1%,91.5%,and 2.4%,respectively.The three components formed three homogeneous peaks after going though Sephadex G-100 gel column and were named as GLIP-1,GLIP-2 and GLIP-3.The antioxidant activities of LIP and GLIP-2 were evaluated by testing the scavenging ability of free radicals(·OH,DPPH·,O₂^-·).The IC₅₀value was as standard for all the experimental data,·OH clearance capacity is:GLIP-2>LIP,O₂^-·clearing capacity is:LIP>GLIP-2,DPPH clearance capacity is:LIP>GLIP-2.