Study On Extraction Of Polysaccharides In Morchella Esculenta And Its Antioxidant Activities In Vitro

Polysaccharides are one of the main biological active materials from Morel. They have been looked as an important class of bioactive natural products in the medical application due to their special biological activities such as antioxidant activity, anti-aging, immunoregulation effects, etc. In this study, the extraction conditions and antioxidant activity of polysaccharides were studied. And, in order to explore the effects of selenium and zinc on the antioxidant activity of polysaccharides, we cultivated Morel by adding external selenium and zinc trace elements. This experiment provides the reference data for further research of Morel.(1) On the basis of single factor experiments, Response surface methodology(RSM) methods were applied for the optimization of p H, the ratio of ethanol to sample, ethanol volume fraction and the precipitation time. The yield of polysaccharide produced by Morels was used as the selection criteria. Based on regression analysis, the optimal theoretical extraction conditions were determined: p H 7.43, the ratio of ethanol to sample was 3.29:1, the ethanol volume fraction was 85.12%, alcohol precipitation time was 23.54 h. Under these conditions the polysaccharide yield was 724.386 μg/m L. The reliability and feasibility analysis of the experimental results showed that the model was right.(2) The vitro antioxidant activity of extracellular polysaccharides(EPS) and intracellular polysaccharides(IPS) from Morel were evaluated by assays of various antioxidants in vitro systems, including superoxide anion, hydroxyl radical-scavenging activity and the total reducing power. Broth and mycelium extract were the positive control. The results show that: The two kinds of polysaccharides on O2-· and ·OH both have the ability to clear, but far lower than the same concentration of the fermentation broth and extract; the polysaccharides scavenging ability on O2-· was EPS > IPS, on ·OH was IPS> EPS.(3) On the basis of single factor experiments, the optimal concentration of selenium and zinc were 1.2 mmol/L and 0.9 mmol/L. And, measuring the antioxidant activities of the polysaccharides, VC was the reference. The results show that the scavenging rate of O2-· and ·OH was increased by 50% and 20% respectively when the selected selenium and zinc elements was added. When the concentration of the samples solution were 3 mg/m L, the scavenging rates of intracellular polysaccharides containing selenium(IPS-Se), intracellular polysaccharides containing zinc(IPS-Zn) and intracellular polysaccharides(IPS) for O2-· were 98.46%, 96.7%, 48.5% and ·OH scavenging rates were 50.64%, 40%, 30.35%, which were all lower to the same concentration of VC. By comparing the IC50,we found that the antioxidant activities of selenium polysaccharides were significantly higher than normal polysaccharides, and zinc added made the intracellular polysaccharide scavenging rate of O2- · increased by 3 times.