Isolation,Purification And Bioactivity Of Polysaccharide From Fruiting Body Of Laetiporus Sulphureus

Laetiporus sulphureus,also known as sulfur porous bacteria and sulfur colored porous bacteria,is a precious wild fungus in Northeast China.Edible,but also has the role of regulating the body,improving health and disease resistance.In this work,the wild L.sulphureus was used as the experimental raw material to extract the crude polysaccharide of sulfur bacteria by the method of water extraction and alcohol precipitation.The effects of liquid to material ratio,extraction temperature,extraction time and extraction times on the expected yield of crude polysaccharide were investigated.Combined with a single-factor experiment and response surface design analysis,the optimized extraction conditions suitable for polysaccharides extraction were chosen as follows: extraction time is 2h,extraction temperature is 100 ° C,ratio of water to raw materrials is 34,and extraction frequency is 2.Under the optimized conditions,the experimental yield of L.sulphureus polysaccharides(4.44%?0.45%,W/W)was close to the expected yield of(4.47%),which further proves the rationality and credibility of the model.Combined with repeated freeze-thaw,protease digestion,Sevag reagent,dialysis and other methods,which can removed the protein and other impurity components in crude polysaccharide of sulfur bacteria were,and the purified sulfur bacteria polysaccharide LSP was obtained.Three main homogeneous polysaccharide components,LSP I-b,LSP II-a and LSP II-b,were isolated by combining DEAE-Cellulose DE-52 anion exchange chromatography and Sepharose CL-6B chromatography.The polysaccharide content was 98.7%,89.9% and 92.7%,respectively.All three polysaccharide components contain proteins but do not contain uronic acid.IR analysis showed that the characteristic absorption peaks of LSP I-b,LSP II-a and LSP II-b were all unique to fungal polysaccharides.The biological activities of polysaccharide components were verified by examining the antioxidant activity and bacteriostatic ability of polysaccharides in vitro.The assay of antioxidant activity in vitro showed that LSP,LSP I-b,LSP II-a,and LSP II-b can partly clear the superoxide radical,hydroxyl radical and DPPH free radical.Especially,DPPH free radical scavenging ability was relatively high,but the superoxide anion radical,hydroxyl radical scavenging activity and reducing power were relatively lower.The sequence of scavenging ability for various polysaccharide components were DPPH radical> superoxide anion> hydroxyl radical.Compared with LSP II-b,LSP I-b and LSP II-a have lower DPPH radical scavenging ability and total reducing power,but have stronger superoxide anion radical and hydroxyl radical scavenging ability.The antioxidant capacity of LSP,LSP I-b,LSP II-a and LSP II-b was concentration dependent.Bacteriostasis tests showed that polysaccharides had no inhibitory ability against Staphylococcus aureus and Escherichia coli within the experimental concentration range.