Purification,Characterization And Bioactivity Of Extracellular Polysaccharides From Bjerkandera Fumosa

Bjerkandera fumosa is a medicinal fungus of Basidiomycota,which has been widely used in the folk,but its active components and mechanism are still unclear.The liquid fermentation of Bjerkandera fumosa and the structure,physicochemical properties and immunological activity of mycelial polysaccharides were systematically studied in our laboratory.On this basis,the extracellular polysaccharides of Bjerkandera fumosa fermented with glucose as carbon source were prepared,separated and purified,and their properties,structures and biological activities were studied.The main results are as follows:(1)Preparation and physicochemical properties of extracellular polysaccharides from Bjerkandera fumosaExtracellular polysaccharide EPBF was prepared from Bjerkandera fumosa cultured in liquid glucose fermentation medium with yield of 0.9 g/L.The results of physicochemical properties analysis showed that EPBF was mainly composed of mannose,rhamnose,galacturonic acid,glucose,galactose,arabinose and fucose in the molar ratio of 57.6:1.9:2.5:25.2:6.2:4.7:2.0,without nucleic acid and protein;its average molecular weight was 3.5×10~5 Da;the contents of total sugar,glucuronic acid,polyphenols and ash were 63.57%,7.98%,0%and 15.46%,respectively.(2)Isolation,purification,structure and physicochemical properties of extracellular polysaccharides from Bjerkandera fumosaEPBF was separated by DEAE-32 cellulose anion chromatography and Sepharose G-75 gel column,and purified component EPBFG was obtained.HPGLC analysis showed that the component was homogeneous polysaccharide with a molecular weight of 4.4×10~4 Da.It is mainly composed of mannose,rhamnose,galacturonic acid,glucose,galactose and arabinose in the molar ratio of49.9:3.5:2.2:26.9:4.4:11.2.The total sugar and ash content are 61.98%and 6.34%,respectively.FT-IR and NMR analysis showed that EPBFG was mainly composed of?-Glc,?-Gal and?-Man,while EPBFG did not contain peptide chains or proteins.The glycocyclic form of EPBFG was pyran glycocyclic and the glycoside bond configuration was?.(3)Study on the Biological Activity of Extracellular Polysaccharides from Bjerkandera fumosaThe antioxidant activity of the extracellular polysaccharide EPBF and its purified component EPBFG from Bjerkandera fumosa was determined.The results showed that DPPH free radical scavenging activity was 70.22%and 83.89%,hydroxyl radical scavenging activity was 70.99%and 81.87%,ferrous ion chelating activity was78.29%and 90.15%under 5 mg/mL conditions,and the reducing power was 0.59 and0.75 under 12 mg/mL conditions,respectively.The antioxidant activity of purified EPBFG was higher than that of EPBF.The antitumor activity of EPBF and its purified component EPBFG from Bjerkandera fumosa in vitro was also tested.tudies have shown that EPBF and EPBFG can inhibit the proliferation of Hela cell line of cervical cancer and have no toxic effect on H8 cell line of normal human body.The anti-tumor activity of purified EPBFG at the same concentration was higher than that of EPBF in vitro.The inhibition rate of EPBFG on Hela cell line reached 48.44%at 2.5 mg/mL concentration.EPBFG could promote the proliferation of H8 cells at low concentration(?1.5mg/mL),and inhibit the proliferation of H8 cells at high concentration,but the inhibition rate was less than 3%.Flow cytometry was used to detect the anti-tumor mechanism of polysaccharides.It was speculated that EPBFG could inhibit the proliferation of Hela cell line by inhibiting cell cycle,thus exerting its anti-tumor effect.