Acetylated Modification And Antioxidant Activity Of Polysaccharide Form Auricularia Auricular

Auricularia auricula [Auricularia auricular (Hook L.ex) Underw], one of the edible-medicinal fungus, has possessing a broad range of potential biological activities. These biological activities include decreasing blood lipids, hypoglycemic and anti-aging activities. Therefore, it is extremely significant and valuable to study on Auricularia auricular. Previous studies have shown that the biological activities of polysaccharide could be improved by polysaccharide modification. In this paper, the process of polysaccharides extracting of Auricularia auricula was optimized, and acetylation of Auricularia auricula polysaccharide was prepared, separated and purified. Moreover, acetylated polysaccharide components were detected by infrared spectroscopy (IR) and Congo red test, and their antioxidant activities were studied.Snail enzyme assisted extraction of Polysaccharide from Auricularia Auricula was studied. The optimum conditions of extracted polysaccharide were determined by single factor experiment and response surface methodology. Results showed that the optimal enzymatic hydrolysis conditions were enzymatic hydrolysis time 2.50 h, enzymatic hydrolysis temperature 55.00?, pH 6.80 and enzyme concentration 1.30%. After enzymatic hydrolysis, under conditions of NaOH concentration 0.4 mol·L-1, extraction time 2 h, extraction temperature 90?, the yield of polysaccharide was 31.1%. Comparing with the theoretical prediction value 30.34%, the relative error was about 0.76%. At the same time, the yield of polysaccharide under these conditions was higher than that under alkaline alone conditions.The preparation conditions of acetylated Auricularia auricular polysaccharide were optimized by combination design of quadratic regression orthogonal. In this experiment, amide, acetic anhydride and N-Bromo succinimide (NBS) were respectively used as solvent, acetylated reagent and catalyst. The reaction time, reaction temperature, acetylated reagents and NBS addition were used for investigation of variable factors, and acetylated degree of substitution was used as the metric of choice. The final data was analyzed by SPSS software. The results showed that reagent dosage of acetylated and NBS addition of polysaccharide from Auricularia auricular had a significant effect (P< 0.05) on the acetylated polysaccharide preparation. After equation calculations, the optimal acetylated polysaccharide preparation conditions were reaction time 2.0827 h. reaction temperature 80?, acetylating reagent dosage 32.5 mL, NBS addition 1%. By the infrared spectrum detection of original polysaccharide and acetylated polysaccharide, it showed the method of acetylated Auricularia auricular polysaccharide preparation was feasible.Auricularia auricular polysaccharide by acetylation DEAE cellulose-52 purification, get seven components, for the components that the glucan gel G-75 further purification, get relatively pure polysaccharide components of acetylated. IR results show that Auricularia auricula raw sugar and acetylation of Auricularia auricula polysaccharide, separation and purification of each component, has general polysaccharide in the infrared spectral characteristics of structure in the peak, in about 2900cm"1 for the C-H stretching vibrations of the CH2, about 3400 cm-1 for the -OH stretching vibration of O-H and N-H stretching vibration. Among them, the acetylation of Auricularia Auricula polysaccharide, component 3 and 4, component 5 and 6 in the range of 1720cm-1?1770cm-1 for the C=O stretching vibration, that acetylation of Auricularia polysaccharide and component 3 and 4, component 5 and 6 acetylation success. Acetylation of Auricularia auricula polysaccharide is purified and separated components were introduced in the acylamino (?)NHR, characteristic absorption peak at 1680cm-1?1630cm-1, that introducing acylamino structure of polysaccharide. The Congo red experiment show that the complex maximum absorption wavelength red shift compared with Congo red indicated that all samples polysaccharide does not have the three spiral stereo structure.The antioxidant activities of original polysaccharide and acetylated polysaccharide components of Auricularia auricula were studied. The results showed that original polysaccharide and acetylated polysaccharide components from Auricularia auricular had the ability of scavenging hydroxyl free radical and superoxide anion. Moreover, acetylated polysaccharide components had reduction ability, and the antioxidant activities of these components were slightly higher than those of original polysaccharide.