Studies On Optimization Of Extraction Process And Antioxidant Ability In Vitro Of Polysaccharides In Dictyophora Indusiata

Dictyophora indusiata polysaccharides （DIPs）, the main bioactive component ofDictyophora indusiata, which was treated as dual-purpose plant of food and medicine,was greatly valuable for exploitation and utilization. In order to improve the yield ofDIPs, and develop a new efficient and time-saving extraction process, responsesurface methodology （RSM） based on Box-Behnken design （BBD） was employed tooptimize the enzyme-assisted extraction procedure of the polysaccharides from stipeof Dictyophora indusiata. And the procedure was compared with the traditionalhot-water extraction process. Further, the hot-water extraction and enzyme-assistedextraction process were adopted to obtain the polysaccharides from stipe and bacteriaskirt of Dictyophora indusiata, and the polysaccharides were characterized byinfrared （FT-IR） and transmission electron microscopy characterization （TEM）, thenthe radical scavenging activities of DPPH·and O^2-·and reducing power were adoptedto test the antioxidant ability of different polysaccharides in vitro.The enzyme-assisted extraction procedure of DIPs was adopted, and theprocedure was optimized by RSM, then the optimal conditions were obtained:cellulose, papain and pectolyase concentration were2.0%（wt.%of D. indusiatapowder）,2.0%and1.5%. And extraction temperature, extraction time and pH were52.5°C,105min and5.25, respectively. Under these conditions, the experimentalyield of polysaccharides was9.77%.Dictyophora indusiata polysaccharides were characterized to analyze the effect ofdifferent extraction methods on the structure and morphology of polysaccharides. Theresults of characterization showed were as follows: the FT-IR spectra ofenzyme-assisted extraction of polysaccharides than hot-water extraction in hydroxyl,pyranoside and carbonyl, etc. showed a stronger absorption peak; and from the TEMspectra, the round molecules particles of polysaccharides extracted byenzyme-assisted extraction were larger than them from hot-water extraction. Thecharacterization results confirmed the advantages of enzyme-assisted extractionmethod.The radical scavenging activities of DPPH·and O^2-·and reducing power wereadopted to compare the antioxidant ability of different Dictyophora indusiata polysaccharides. DPPH·and O^2-·radical scavenging and reducing power test resultsshowed that: the antioxidant ability of enzymatic extraction polysaccharides wasbetter than hot-water extraction polysaccharides. Between them, the enzymaticextraction bacteria skirt polysaccharides possessed the best antioxidant activity: whenthe polysaccharides concentration was1.0mg/mL, the radical scavenging rate onDPPH·was86.94%; the absorbance at700nm could up to0.387; when thepolysaccharides concentration was2.0mg/mL, the radical scavenging rate on O^2-·was33.41%. In contrast, DIPs’ radical scavenging on DPPH·and reducing power werebetter quality, whereas their scavenging ability on O^2-·were relatively weaker.Experimental results in this study showed that enzyme-assisted extractiontechnology can not only improve the polysaccharide yield and efficiency, but also canprotect the structure and biological activity of polysaccharides.