新品系木耳的基源、營養成分及不可消化多醣物化特性研究

Study on the phylogenetic relationship, nutritional composition and non-digestible polysaccharides physicochemical properties of new wood ear strain

陳嬿婷(Yen-Ting Chen)

指導教授 ： 黃良得

國立臺灣大學/生物資源暨農學院/農業化學研究所/碩士(2015年)

https://doi.org/10.6342/NTU.2015.02633

摘要

自古以來，菇類廣泛用於食材及藥材且具有多種生物活性物質，其中又以多醣體 (Polysaccharides) 因具有抗癌及免疫調節活性受到重視；菇類多醣大多為 β-葡聚醣 (β-glucan)。本研究之新品系木耳俗稱白玉耳為康建生物科技公司提供，研究目的為探討白玉耳之基源、基本營養成分及不可消化多醣之物化特性。白玉耳經 ITS (internal transcribed spacer) 定序分析結果發現白玉耳為毛木耳之變異種，其 ITS DNA 序列已於 NCBI 登錄，登錄碼為 KJ627785，命名為 Auricularia polytricha cv. Kangjian。基本營養成分分析結果顯示白玉耳蛋白質含量顯著高於毛木耳及白木耳。實驗進一步萃取同品種的白玉耳及毛木耳之不可消化多醣，並比較兩者之物化特性，結果顯示白玉耳之不可消化多醣產率為 9.6%，顯著高於毛木耳不可消化多醣的 7.4%。分子量分析結果得知白玉耳不可消化多醣及毛木耳不可消化多醣之分子量皆大於 1400 kDa，此兩種菇類之不可消化多醣皆具有典型的多醣 IR 圖譜，此外，白玉耳不可消化多醣較毛木耳不可消化多醣具有更多的游離態羧基 –COOH 及 β-糖苷鍵。木糖為白玉耳不可消化多醣中最主要的單醣，甘露糖則為次要組成分，且亦含有葡萄糖醛酸、葡萄糖、岩藻糖及半乳糖，然而毛木耳不可消化多醣之主要單醣為葡萄糖，甘露糖與木糖次之，此外，亦含有少量之半乳糖、葡萄糖醛酸以及阿拉伯糖。實驗進一步觀察兩種不可消化多醣對於小鼠巨噬細胞 RAW 264.7 之存活率，以及對於抑制 LPS 誘導小鼠巨噬細胞 RAW 264.7 生成 NO量之影響，結果顯示兩種不可消化多醣於 5、10、20、40 μg/mL 均不影響小鼠巨噬細胞 RAW 264.7 之存活率。白玉耳不可消化多醣及毛木耳不可消化多醣之抑制 NO 活性皆呈現濃度效應，於 40 μg/mL 兩者具有最佳之抑制效果，且此濃度下白玉耳不可消化多醣之抑制活性顯著優於毛木耳不可消化多醣。綜合以上結果可知，白玉耳為新品系的毛木耳，其 rDNA 序列已登錄於 NCBI 資料庫。白玉耳不可消化多醣與同種之毛木耳不可消化多醣之多醣物化特徵不全然相同，其不可消化多醣能有效抑制小鼠巨噬細胞 RAW 264.7 受 LPS 誘導之 NO 產生，顯示白玉耳不可消化多醣具有抗發炎活性。

關鍵字

毛木耳 ； ITS ； 不可消化多醣 ； 物化特性

並列摘要

For millennia, mushrooms have been widely used as an edible and medical resource. A number of bioactive molecules have been identified in many mushroom species. Polysaccharides are the best known and most potent mushroom-derived substances, of which are known to possess antitumor and immunomodulating properties; they are mainly β-glucan. The mushroom used in this study is a kind of wood ear, also known as Bai-yu-er (白玉耳), which was provided by Kang Jian Biotech Co., Ltd.. The aims of this study were: (i) to investigate the phylogenetic relationship and nutritional composition of Bai-yu-er; (ii) to examine the physicochemical properties of Bai-yu-er non-digestible polysaccharides; and (iii) to evaluate the inhibitory effect of non-digestible polysaccharides on LPS induced NO production in RAW 264.7 cells.
Based on phylogenetic analysis, rDNA ITS sequences of Bai-yu-er was shown to be related to Auricularia polytricha. Therefore the scientific name of Bai-yu-er was named as A. polytricha cv. Kangjian, of which the rDNA sequence has been submitted to NCBI with accession number KJ627785. Nutritional composition analysis showed that the protein content of Bai-yu-er was significantly higher than A. polytricha and Tremella fuciformis. Non-digestible polysaccharide yield of Bai-yu-er (9.6%) was significantly higher than A. polytricha (7.4%). Molecular weight of non-digestible polysaccharides of these two mushroom were found to be larger than 1400 kDa. IR spectra showed that Bai-yu-er non-digestible polysaccharides had stronger free carboxyl group and β-glycosidic linkage adsorption than A. polytricha. Xylose was the main monosaccharide of Bai-yu-er non-digestible polysaccharides, followed by mannose and a small amount of galactose, glucornic acid, and fucose. Glucose was the main monosaccharide of A. polytricha non-digestible polysaccharides, followed by mannose and xylose, a small amount of galactose, glucornic acid, and arabinose.
Results showed that treatment in RAW 264.7 cells with 5, 10, 20 and 40 μg/mL of these two non-digestible polysaccharides exhibited no effect on cell viability. At 40 μg/mL, two non-digestible polysaccharides exhibited strong potency on inhibiting NO production in a dose-dependent manner. At the same concentration, the NO inhibitory effect of Bai-yu-er non-digestible polysaccharides was significantly better than A. polytricha. Taken together, this study was the first research on examing the phylogenetic relationship of Bai-yu-er. The physicochemical properties of Bai-yu-er and A. polytricha non-digestible polysaccharides were different. Bai-yu-er non-digestible polysaccharides could effectively inhibited the production of NO induced by LPS in RAW 264.7 cells, suggested that it had anti-inflammatory activity.

並列關鍵字

Auricularia polytricha ； internal transcribed spacer ； non-digestible polysaccharides ； physicochemical properties

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