Research On Physicochemical Characteristics And Antioxidant Activity Of Polysaccharides Extracted From Armillariellamellea

In this paper,Armillariellamellea as experimental materials,the extraction,purification,physicochemical and structural characteristics,as well as antioxidant activities of the polysaccharides were systematically studied.The optimum ultrasonic crushing extraction(UDE)conditions of polysaccharide from Armillariellamelleawere optimized by response surface methodology(RSM):ultrasonic power 915.00 W,temperature 69.27?and time39.13 min,the crude polysaccharides(AMPs)yield was 19.5%.Under revised optimal conditions(power 915 W,temperature 69?and time 39 min),the experimental yield of AMPs was 19.89±0.86%,which is close to the predicted yield of 19.5%,indicating that our model is accurate.Then two omogeneous polysaccharides fractions(AMPs-1-1 and AMPs-2-1)were obtained by removed protein with the Sevag method,dialyzed against water to remove small molecule ingredients,separated using DEAE-Sepharose Fast Flow anion-exchange,and purified by Sephadex G-100 gel filtration chromatography,respectively.The total sugar contents of AMPs-1-1 and AMPs-2-1 were determined by phenol-concentrated sulfuric acid method,which were 91.2%and 88.5%,respectively.The protein contents of AMPs-1-1 and AMPs-2-1 were 2.17%and 4.03%respectively,by the Bradford method.The uronic acid contents of AMPs-1-1 and AMPs-2-1 were measured by a modified hydroxydiphenyl assay,which were 1.28%and 3.36%,respectively.The physicochemical properties and structural characteristics of two fractions were characterized and compared using high performance gel permeation chromatography(HPGPC),high performance liquid chromatography(HPLC),gas chromatograph-mass spectrometer(GC-MS),Fourier Transform infrared(FT-IR)and nuclear magnetic resonance(NMR)spectra,respectively.AMPs-1-1 was a acidic heteropolysaccharide with average molecular weights of 1.23×10~5 Da,and composed of Glc,Gal and GlcA with mole percentages of 89.06%,9.59%and 1.34%,respectively,owning a backbone structure of(1?)-?-D-Glcp,(1?3,6)-a-D-Glcp and(1?3)-?-D-Glcp residues.AMPs-2-1 was also aacidic heteropolysaccharide with average molecular weights of 6.76×10~4Da,and composed of Glc,Gal,GlcA and Man with mole percentages of 65.28%,22.87%,2.87%and 8.98%,containing a main backbone chain of(1?3,6)-?-D-Glcp and(1?6)-?-D-Glcp residues.FT-IR showed that AMPs-1-1 and AMPs-2-1 both had characteristic absorption peaks of multiple saccharides,both containing uronic acid and protein,with?-and?-glycosidic bond configuration and pyranose rings.The antioxidant activities of AMPs-1-1 and AMPs-2-1 were determined by FRAP,DPPH?,ABTS~+?and ORAC scavenging test,and the results showed that the two polysaccharides had significant antioxidant activities,and their antioxidant activities were positively correlated with the concentration of polysaccharides.AMPs-2-1 possessed obviously antioxidant activities in terms of stronger scavenging activity against DPPH?and ABTS~+?,higher FRAP and ORAC value than AMPs-1-1,indicating that the antioxidant activities of AMPs-2-1 with relatively lower molecular weight and higher glucuronic acid were higher than those of AMPs-1-1.These results suggested that UDE is an effective extract technology,and AMPs-2-1 could be explored as potential natural antioxidants agents.