碩士 / 明新科技大學 / 化學工程研究所 / 98 / Armillariella mellea is one of the fungi food-medicine mushrooms to tranquilize the central nervous system and to reduce the mice death rate induced by nicotine. It can also treat dizziness, palsy, insomnia, tinnitus, etc., simultaneously. Many researchers have demonstrated that A. mellea polysaccharides are excellent in anti-tumor and antioxidant activities. Emphasis of this study has been laid upon the culture condition optimization in 20-L stirred-tank cultures and the isolation of exopolysaccharides (EPS) from A. mellea for the investigation of antioxidant activities and structure characteristics. The crude EPS from submerged cultures of A. mellea was purified by using Sepharose CL-4B column chromatography with two EPS peaks (EPS-A and EPS-B) eluted. Antioxidant activity results point out that EPS-B has high reducing powers, scavenging effects on 1,1-diphenol-2-picrylhydrazyl radicals and antioxidant activities. Corresponding EC50 values are 14.44 mgmL-1, 2.28 mgmL-1 and 3.41 mgmL-1. The high EC50 values of chelating effects and scavenging effects on superoxide anions of EPS-A are 2.06 mgmL-1 and 0.12 mgmL-1, respectively. Because all EC50 are below 10 mgmL-1 except reducing powers, EPS-A and EPS-B in A. mellea are of exceptional antioxidant activities. In addition, the protein/polysaccharide ratios of EPS-A and EPS-B are 21.74% and 9.12%, respectively. Molecular weight analyses of EPS-A and EPS-B by using Molecular Sieve chromatography tell that EPS-A is 1.39×105 Da in mocecular weight and EPS-B is 1.19×104 Da. Composition analyses of neutral monosaccharides in EPS-A and EPS-B reveal that glucose is the major monosaccharide of EPS-A w galactose and glucose are the major monosaccharides of EPS-B. Structures were elucidated by NMR in 1H-NMR and 13C-NMR spectral for comparison with known compounds that have β-D-glucan chains. IR spectrum shows an absorption bond of sugar functional group from polysaccharides. The higher the polysaccharide concentration, the more the murine tumor necrosis factor-alpha (mTNF-α). The maximum mTNF-α concentration values of EPS-A and EPS-B are 740.36±22.81 pgmL-1 and 680.10±12.60 pgmL-1, respectively. Comprehensive results confirm that the bigger the molecular weights of purified polysaccharides, the better the murine tumor necrosis factor-alpha (mTNF-α) values. Higher ratios of protein/polysaccharide of purified polysaccharides correspond proportionally to better murine tumor necrosis factor-alpha (mTNF-α) values. With the structure of purified polysaccharides, murine tumor necrosis factor-alpha (mTNF-α) values are related to the structure of purified polysaccharids containingβ-D-glucan. The higher molecular weight and protein/polysaccharide ratio of purified polysaccharides bear out antioxidant activities of better chelating effects and scavenging effects on superoxide anions. Since the molecular weight is related to protein/polysaccharide ratios of purified polysaccharides, the lower molecular weight and protein/polysaccharide ratios of purified polysaccharides are beneficial to reducing powers, scavenging effects on 1,1-diphenol-2-picrylhydrazyl radicals and antioxidant activities.
| Identifer | oai:union.ndltd.org:TW/098MHIT5062003 |
| Date | January 2010 |
| Creators | 羅紫櫻 |
| Contributors | 龍明有 |
| Source Sets | National Digital Library of Theses and Dissertations in Taiwan |
| Language | zh-TW |
| Detected Language | English |
| Type | 學位論文 ; thesis |
| Format | 118 |
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