靈芝子實體熱水取萃物中的多醣分子特性   全文下載

Molecular Characterization of Polysaccharides in Hot-Water Extracts of Ganoderma lucidum Fruiting Bodies

利用高效能分子篩層析配合多角度雷射光散射分析法（HPSEC-MALLS）分離靈芝子實體熱水萃取物中的多醣組成並檢測其分子量與分子量分佈情形。發現在靈芝熱水萃取物中有三種分子量不同的多醣，分別佔31，46 與23%的重量比例，重量平均分子量由大到小依序為2.08 × 106，2.3 × 104與1.2 × 104 g／mol。利用酒精濃度分級沈降對此多醣進行劃分，可獲得具代表此三種多醣的多醣區分以進行性質分析。其中分子量最大的多醣區分，以單醣組成、aniline blue染色及1H-與13C-NMR光譜分析確認結構為具分支的（1 → 3, 1 → 6）-β-D- 聚葡萄醣，其分支為單一葡萄糖基接於O-6的位置，分支度為0.35。此聚葡萄醣於常溫下略溶於水，為靈芝萃取物的主要活性多醣組成，具有明顯刺激人體單核細胞產生TNF-α的活性。第二與第三區分則為葡萄糖、半乳糖與甘露糖組成的異質多醣，活性較不顯著。利用HPSEC-MALLS可觀察到多醣分子聚集的現象。"

Polysaccharide components in hot-water extract of Ganoderma lucidum fruiting bodies were separated and their molecular weights and distribution profiles were measured using high-performance size-exclusion chromatography with multi-angle laser light scattering detection (HPSEC-MALLS). Three polysaccharide groups were found in the extract with a weight percentage of 31, 46 and 23%, respectively. The weight-average molecular weights of these groups were 2.08 ¥ 106, 2.3 ¥ 104 and 1.2 ¥ 104 g/mol, respectively. The representative fractions of these 3 groups were obtained using differential precipitation with ethanol at 20, 60 and 80% (v/v) concentrations for further property study. The first group that had the largest molecular size was branched (1→3)-b-D-glucan with single b-Dglucosyl side chains at the O-6 positions, as revealed from sugar composition analysis, aniline blue assay and 1H- and 13C-NMR spectroscopy. (1→3, 1→6)-b-D-glucan was the major active polysaccharide and showed significant tumor necrosis factor-a (TNF-a) releasing stimulation activity from human mononuclear cells (MNC). The glucan was slightly soluble in water at ambient temperature. The second and third groups that showed slight modulating activity consisted of D-glucose, D-galactose and D-mannose at different ratios. Aggregation of polysaccharide molecules was also revealed by HPSEC-MALLS study. 利用高效能分子篩層析配合多角度雷射光散射分析法（HPSEC-MALLS）分離靈芝子實體熱水萃取物中的多醣組成並檢測其分子量與分子量分佈情形。發現在靈芝熱水萃取物中有三種分子量不同的多醣，分別佔31，46 與23%的重量比例，重量平均分子量由大到小依序為2.08 × 106，2.3 × 104與1.2 × 104 g／mol。利用酒精濃度分級沈降對此多醣進行劃分，可獲得具代表此三種多醣的多醣區分以進行性質分析。其中分子量最大的多醣區分，以單醣組成、aniline blue染色及1H-與13C-NMR光譜分析確認結構為具分支的（1 → 3, 1 → 6）-β-D- 聚葡萄醣，其分支為單一葡萄糖基接於O-6的位置，分支度為0.35。此聚葡萄醣於常溫下略溶於水，為靈芝萃取物的主要活性多醣組成，具有明顯刺激人體單核細胞產生TNF-α的活性。第二與第三區分則為葡萄糖、半乳糖與甘露糖組成的異質多醣，活性較不顯著。利用HPSEC-MALLS可觀察到多醣分子聚集的現象。