| Agrocybe aegerita belongs to Basidiomycetes, Agaricales, Bolbitiaceae, is rich in a variety of biologically active substances, such as proteins, bacterial proteins, dextran, carbohydrate, trace elements, etc. Agrocybe has an important role in anti-oxidation, anti-aging, enhance immunity, etc. It is a relatively common edible and medicinal fungi. Selenium is a trace element necessary for life activities, and is related to liver function muscle metabolism and antioxidant activity.In this paper, the Se concentration condition in the liquid medium was decided, and the extraction conditions of A.aegerita exopolysaccharide (EPS) and intrecellular Se-polysaccharide (ISPS) in submerged culture were optimized on the basis of Plackett-Burman (PB) design and response surface methodology (RSM). The separation and purification of EPS、IPS、ISPS and their monosaccharide and molar ratio were evaluated. The in vitro and in vivo antioxidant activities of EPS、IPS(intracellular polysaccharide) and ISPS were decided.(1) By comparing biomass and Se rich rate of mycelia in different Se concentration, results showed that the best concentration of Se in the liquid medium is4mg/L. At this concentration, the Se rich ratio was65%.(2) Through PB and response surface optimization, the EPS optimum extraction conditions were:concentration multiple3, ethanol multiple2.4, alcohol precipitation temperature-3.8℃, under these conditions, EPS forecast yield of0.70g/L, verify the yield of0.71g/L; the optimum extraction conditions of the selenium-rich intracellular polysaccharide were:pH8, extraction temperature83℃, alcohol precipitation temperature12℃, Under the condition of the ISPS to predict rate was10.56%, the verification rate11.02%(3) Through the DEAE-cellulose column, EPS contained three components:EPS-1, EPS-2, EPS-3; IPS has three components:IPS-1, IPS-2, IPS-3; ISPS in three components equally:ISPS-1, ISPS-2, ISPS-3. Although the IPS and the ISPS both had three components in the same peak position, the proportion of every component was different. Selenium affected the composition of the polysaccharides.(4) After gas chromatograph analysis, EPS contained rhamnose and glucose with the content of7.1%,2.53%, the molar ratio was2.8:1; IPS contained rhamnose, arabinose, mannose and glucose, with the content of5.32%,0.27%,0.54%,0.72%, the molar ratio was29.2:1.8:3:4; ISPS contained rhamnose, arabinose, mannose, glucose and galactose with the content of7.9%,0.72%,2.28%,5.07%,0.73%, the molar ratio was29:3:1:18.8:2.7.(5) Antioxidant activities in vitroThe EPS-2, showed a superior antioxidant capacity. Reducing power of EPS-2is10times higher than EPS at the same concentration. The results showed that both IPS and ISPS had strong antioxidant activities in vitro, but Sodium Selenite had none. ISPS had higher reducing power activity and stronger radical scavenging ability than IPS, indicating that the adding of selenium combined with polysaccharide and improved oxidation resistance.(6) Anti-ageing activities of EPS. IPS and ISPS in vivoThe results showed that EPS. IPS and ISPS could significantly increase the content of superoxide dismutase (SOD), total antioxidant capabilities(T-AOC), while significantly decrease the content of malondialdehyde (MDA) and cholesterol levels, which indicated that these three polysaccharides could improve the body’s resistance to senile and mitigate the damage of lipid peroxidation.The results showed that A.aegerita extracellular polysaccharide, intracellular polysaccharide and intracellular selenium-polysaccharide had strong in vivo and in vitro antioxidant capacity, and within the scope of the experimental level, Se is added to improve the antioxidant capacity of A.aegerita intracellular polysaccharides, which can lay the foundation of researching A.aegerita polysaccharides on antioxidant mechanisms, structure-activity relationships and selenium-rich foods. |
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