糙米化學組成及其非消化水溶性多醣結構特徵

Chemical Composition and Molecular Characteristics of indigestible Water-Soluble Polysaccharides in Brown Rice

郭巧妤(Chiao-Yu Guo)

指導教授 ： 呂廷璋

國立臺灣大學/生物資源暨農學院/食品科技研究所/碩士(2017年)

https://doi.org/10.6342/NTU201603395

摘要

糙米為容易取得的全穀食物也是膳食纖維的豐富來源，本研究使用台灣產台稉九號、台南11號及台中秈10號糙米為原料，分析其化學與醣類組成。測定其游離酚酸含量，研究結果顯示咖啡酸含量約3.5~4.3 µg/g，綠原酸約14.0~18.9 µg/g，阿魏酸2.93~3.7 µg/g，沒食子酸約0.8~0.9 µg/g，對位香豆酸3.0~3.9 µg/g，原兒茶酸約0.6~0.7 µg/g，芥子酸約0.9~3.3 µg/g；植物固醇中之游離態植物固醇主要為β-谷固醇，含量約43~47 mg/100 g，另有34~36 mg/100 g 豆甾醇及15~19 mg/100 g 菜油甾醇，此外結合態固醇中的γ-米糠醇為糙米中的特徵成分之一，含量約37~68 mg/100 g。糙米非消化水溶性多醣 (IDPS) 主要為甘露糖、半乳糖及葡萄糖，以甘露糖含量最多，皆高於70%，其餘岩藻糖、鼠李糖、阿拉伯糖及木糖含量皆小於2.5%，另外含有少量酸性糖；甘露糖具有1,2、1,3、1,4、1,6醣苷鍵，另有2,6與4,6分支並含有大量還原端；葡萄糖具有1,4醣苷鍵；阿拉伯糖具有1,5醣苷鍵並含有3,5分支；木糖則有少量1,4、3,4及2,3,4醣苷鍵；使用LM2、LM5、LM6、LM19、LM20及LM21六種單株抗體進行辨識部位親合分析此IDPS，結果顯示台稉9號、台南11號及台中秈10號中具有阿拉伯半乳聚醣-蛋白質、β-1,4-D-半乳聚醣，此外台稉9號與台中秈10號皆含有β-1,4-甘露寡糖辨識部位，而台南11號與台中秈10號含有無甲酯化及甲酯化homogalacturonan。選定台稉九號糙米進行成分分析及細胞試驗，可消化的澱粉含量為76.7%，不可消化的膳食纖維含量為8.0%，包含0.6% 可溶性及7.5% 不可溶膳食纖維；水溶性多醣 (IDPS) 為可溶性膳食纖維中的主要成分，此IDPS在含有轉殖螢光酵素之老鼠巨噬細胞RAW 264.7平台分析中，於濃度50與100 g/mL下可活化NF-κB及iNOS的路徑表現。推測具有1,2、1,3、1,4、1,6、2,4及4,6鍵結的甘露聚醣為糙米IDPS中可刺激巨噬細胞的主要多醣。並將台稉9號糙米IDPS藉由陰離子交換層析管柱依多醣所帶電荷差異進行劃分，各區分皆以甘露糖、葡萄糖及半乳糖為主而甘露糖含量最高，F3區分酸性糖含量最多，並同時存在阿拉伯半乳聚醣與β-1,4-D-半乳聚醣結構位；甘露糖具有1,2、1,3、1,4及1,6鍵結並具有2,6分支，此外F3及F4亦具有2,4、3,4與4,6分支；葡萄糖具有1,3及1,4鍵結並具有2,6分支，此外F1亦具有3,4及2,6分支；半乳糖具有1,3及1,6鍵結，亦有3,6分支；阿拉伯糖具有1,4鍵結並有3,4分支；木糖主要存在於F4區分。

關鍵字

糙米 ； 游離酚酸 ； 植物固醇 ； 非消化水溶性多醣 ； 促發炎 ； 陰離子交換層析 ； 甘露聚醣

並列摘要

Brown rice is easily available whole grain food which is a good source of dietary fiber. In this study use brown rice of Taikeng Nine, Tainan Eleven and Taichung Sen Ten as research materials and analyze its chemical and carbohydrate composition. The results showed that there are about 3.5~4.3 µg/g caffeic acid, 14.0~18.9 µg/g chlorogenic acid, 2.9~3.7 µg/g ferulic acid, 0.8~0.9 µg/g gallic acid, 3.0~3.9 µg/g p-coumaric acid, 0.6~0.7 µg/g protocatechuic acid and 0.9~3.3 µg/g sinapic acid in brown rice. In addition, β-sitosterol, about 43~47 mg/100 g, is the major free form phytosterol in brown rice. Moreover, there are 34~36 mg/100 g stigmasterol and 15~19 mg/100 g campesterol and 37~68 mg/100 g γ-oryzanol which is the one of characteristic component in rice. Water-soluble polysaccharide (IDPS) from brown rice is mainly composed of mannose, galactose and glucose. Mannose over 70% is the most abundant and all of rhamnose, fucose, arabinose and xylose are below 2.5% including little of acidic monosaccharides. In linkage analysis, mannose contain (1,2), (1,3), (1,4), (1,6), (2,6), (4,6) linkage and a lot of terminal, glucose with (1,4) linkage mainly, arabinose with (1,4), (3,4) and (2,3,4) linkage. Use LM2, LM5, LM6, LM19, LM20 and LM21 six kinds of monoclonal antibodies to identify epitopes of the IDPS, showed that Taikeng Nine, Tainan Eleven and Taichung Sen Ten contain arabinogalactan-protein, β-1,4-D-galactan. In addition, Taikeng Nine and Taichung Sen Ten have β-1,4-manno-oligosaccharide recognition site and both of Tainan Eleven and Taichung Sen Ten include methyl-esterified and un-esterified homogalacturonan. Choose Taikeng Nine brown rice to analyze its compositon and perform cell experiment. There are 76.7% digestible starch, 8.0% nondigestible dietary fiber, including 0.6% soluble and 7.5% insoluble dietary fiber. Water-soluble polysaccharide (IDPS) is the main component in soluble dietary fiber and in the analysis of RAW 264.7 macrophages in mice which were transplanted fluorescent enzyme as an immunoassay screening platform, the concentration of 50 and 100 μg / mL would activate the pathway of NF-κB and iNOS expression. Therefore, speculating that mannan with (1,2), (1,3), (1,4), (1,6) and (2,6) linkage in IDPS may be the major polysaccharide which can stimulate macrophages. In addition, separated IDPS from Taikeng Nine by DEAE chromatography, each fraction has mannose, glucose and galactose mainly and the mannose is the highest, and there is the highest acidity sugar content in F3 with arabinogalactan and β-l, 4-D-galactan structure simultaneously; mannose has (1,2), (1,3), (1,4), (1,6) and (2,6) bonds. And F3 and F4 also have (2,4), (3,4) and (4,6) branches; glucose with (1,3) and (1,4) bonds and (2,6) branches, in addition F1 also has (3,4) and (2,6) linkage；galactose with (1,3) and (1,6) bonds and 3,6 branches; arabinose with (1,4) linkage and (3,4) branches; xylose is mainly in F4.

並列關鍵字

brown rice ； free phenolic acids ； phytosterols ； indigestible water- soluble polysaccharide ； proinflammatory ； anion exchange chromatography column ； mannan

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