香菇菌種之胞外水溶性多醣體分析

Abstract

菇類中含有許多引人注目的功能性成分，特別是當中的多醣體已被廣泛的研究其與保健功能之間的關聯性。目前已有多篇的文獻報導指出菇類中的多醣體具有降血糖、降膽固醇、抗炎症、抗菌、降低氧化傷害、傷口癒合、增加肝功能、抗腫瘤作用和免疫刺激等生物活性。此外，學者也指出菇類多醣體的物理及化學特性，如分子量分佈、單糖組成、醣苷鍵的構型和鍵結型態等，與多醣的功能具有很大的關聯性。 此篇論文利用十株香菇 (Lentinula edodes)菌株，L1、L4、L6、L10、L11、L15、L21、L23、L24和L25菌絲體發酵所得的發酵濾液經過酒精沉澱、蛋白質酶、透析和冷凍乾燥等多醣純化的步驟取得香菇菌種胞外多醣體後，利用酚硫酸法、膠體過濾層析法、氣相層析法和傅立葉轉換紅外線光譜儀分析香菇菌種胞外多醣體之多醣濃度、分子量分布、 單糖組成、醣苷鍵的鍵結位置與醣苷鍵的構型，作為進一步分析多醣之生物活性與其組成之間關聯性的研究基礎。結果顯示各個菌株胞外多醣體之傅立葉紅外線光圖譜分析上，香菇菌株胞外多醣體均不含有糖醛酸。此外，L1、L4、L15、L24和L25菌株之胞外多醣具有α型鍵結的glucans；在多醣濃度的分析上以L24具有最高的多醣濃度，而L21與L23則具較低之多醣濃度；再者，膠體過濾層析圖譜、單糖組成或是醣苷鍵鍵結位置的分析結果，顯示出所有菌株之胞外多醣體組成皆十分相似：均包含兩種以上分子量相近的多醣體 (分子量分別介於6.3 × 104 ~ 8.1 × 104與4.0 × 103 ~ 8.5 × 103之間)，具有glucose、mannose、galactose、xylose和arabinose的單糖組成與(1,4)為主鏈、(1,6)分支之glucans。

Edible mushrooms contain interesting functional components. Polysaccharide, in particular, is supposed to be responsible for some healthy properties of mushrooms. It has been reported to have hypoglycemic, hypocholesterolemic, antiinflammary, antibacterial, antioxidative, wound healing, hepatoprotective, antitumor and immune modulating effects. The mushroom polysaccharide of different structure shows different physical and chemical properties, as well as biological functions. The molecular weight distributions, monosaccharide composition, configuration of glycosidic bond and linkage type are several factors concerned. In this study, the ultimate goal is to establish a method for analyzing physical and chemical properties of polysaccharide as the fundamental relationship between structure and bioactivities of mushroom polysaccharide. Ten isolates of Lentinula edodes, including L1, L4, L6, L10, L11, L15, L21, L23, L24 and L25, were investigated. After the fermentation culture was treated with ethanol precipitation, protease digestion, dialysis and freeze-dried, the resulting polysaccharide was analyzed with phenol-sulfuric acid method, size exclusion chromatography, gas chromatography, and Fourier Transform infrared spectroscopy. The Fourier Transform infrared spectroscopy indicated that all stains are absent of uronic acids. In addition, L1、L4、L15、L24 and L25 had a-linked glucans by Fourier Transform infrared spectroscopy analysis. The results of phenol-sulfuric acid analysis suggested that L24 has the highest polysaccharide content. In contrast, L21 and L23 have the lowest content of polysaccharide. Furthermore, all the isolates studied have similar molecular weight distribution (6.3 × 104 ~ 8.1 × 104 and 4.0 × 103 ~ 8.5 × 103). The polysaccharide are composed of five monosaccharides, including glucose、mannose、galactose、xylose and arabinose with the backbone of (1à6)-branched- (1à4)-glucans.