Please use this identifier to cite or link to this item: http://hdl.handle.net/11455/51811
標題: 枸杞之抗氧化與抗致突變性質及其多醣組成分析
Antioxidant and Antimutagenic Properties and Polysaccharide Composition Analysis of Lyciuum chinense
作者: 梁雅婷
Liang, Ya-Ting
關鍵字: Lycium chinense;枸杞;antioxidant properties;antimutagenic properties;polysaccharide;structural analysis;抗氧化性質;抗致突變性質;多醣;結構分析
出版社: 食品科學系
摘要: 
本研究以枸杞作為樣品,對其抗氧化及抗突變性質進行評估,並萃取枸杞之多醣,探討其多醣組成與結構特性。研究所用之樣品枸杞果實含有26.94%水分,其乾物成分中主要以碳水化合物及粗纖維為主,亦含有高量之粗蛋白(13.15%)。
抗氧化性質測定方面,枸杞甲醇萃取物具有較佳的抗氧化性質,不論是在抗氧化力(共軛雙烯法)、還原力、捕捉1,1-二苯基-2-苦味基團、羥自由基及螯合亞鐵離子之能力會隨著其濃度增加而增強;枸杞水萃取物方面具有相同結果,但其效果不如枸杞甲醇萃取物顯著。在天然抗氧化成分方面,枸杞甲醇萃取物中含有抗壞血酸、生育醇、b-胡蘿蔔素和總酚類化合物,但枸杞水萃取物中並沒有發現到生育醇和b-胡蘿蔔素。枸杞甲醇、冷水、熱水和加熱萃取物之總抗氧化成分含量分別為6.29、4.04、6.58和7.57 mg/g。
以安氏試驗法測試枸杞甲醇及水萃取物之毒性、致突變性以及對直接致突變劑N-甲基-N’-硝基-N-亞硝胍、4-硝基-N-氧化物和間接致突變劑苯并[a]之抗突變性。結果顯示在此系統中枸杞水萃取物對鼠傷寒沙門氏桿菌變異株TA97、TA98、TA100及TA102,無論添加或未添加S9鼠肝混合物,都不具毒性及致突變性,而甲醇萃取物在濃度5.0 mg/plate則具有毒性。於抗致突變性測試方面以甲醇萃取物之表現較水萃取物佳。
以2、5小時加熱及熱鹼萃取之枸杞多醣的總醣含量約在43.87~62.83%,其單醣組成以葡萄糖、甘露糖及核糖為主。以膠體過濾層析分離枸杞多醣後得知其分子量在一萬Da以下。在枸杞多醣結構方面,利用X-光繞射儀分析、示差掃描熱分析(DSC)及核磁共振光譜分析(NMR)得知,枸杞多醣之結晶構形以熱鹼萃取者比熱水萃取者排列緊密且規則。
由DSC與NMR分析圖中發現2小時加熱萃取之多醣所含的糖類官能基較5小時熱水萃取物及熱鹼萃取之多醣少,但其吸收峰表現卻較為顯著,DSC結果中也顯示出2小時加熱萃取之枸杞多醣具有較大的放熱反應,推測2小時加熱萃取之多醣較為不純,因此對於多醣構形之明確機制尚待更進一步的純化後再加以探討。
綜合本研究之結果可知枸杞中主要之成分為碳水化合物、粗纖維及粗蛋白,且其甲醇萃取物較水萃取物有良好的抗氧化性而水萃取物不具毒性及致突變性。加熱及熱鹼萃取兩種多醣皆含有小分子之多醣,且單糖組成相似。
關鍵字:枸杞、抗氧化性質、抗致突變性質、多醣、結構分析

The objectives of this research were to study the antioxidant, antimutagenic properties of methanolic and water extracts from L. chinense Mill. , the monosaccharide constituents, and structural analysis of polysaccharides. Their structures were elucidated by spectroscopic analysis and comparison with known compounds. Fruit of L. chinense contained 26.94% of moisture. In dry matter, fibers and carbohydrates were major components, and crude protein (13.15%).
Methanolic extracts from L. chinense showed very high antioxidant properties. Antioxidant activity using conjugated diene method, the reducing power, the scavenging effect on 1,1-diphenyl-2-picrylhydrazyl radicals (DPPH) and the chelating effect on ferrous ions of methanolic and water extracts from L. chinense increased with the increased concentration, but water extracts was not as good as expected. Naturally occurring antioxidant compounds, including ascorbic acid, b-carotene, tocopherols, and total phenols were found in methanolic extracts from L. chinense. However b-carotene and tocopherols were not found in water extracts. Total antioxidant components were 6.29, 4.04, 6.58 and 7.57 mg/g for methanolic, cold water, boiling water, heating water to boiling extracts, respectively.
The concentration of water extracts from L. chinense used in this study was neither toxicity nor mutagenic to the Salmonella typhimurium TA97, TA98, TA100 and TA102. Methanolic extracts of L. chinense contained antimutagens capable of inhibiting the mutagenicity of direct-acting such as MNNG, NQNO the indirect-acting mutagen, B[a]P.
The total sugar contents of boiling alkaline extracts from L. chinense were higher than boiling water extracts. The compositions of neutral monosaccharide in boiling water extracts were ribose, mannose and glucose. Glucose was the major monosaccharide in boiling water and alkaline extracts of polysaccharides from L. chinense. Polysaccharides of L. chinense were separated using gel filtration, and showed a molecular of about 104 Da. X-ray, DSC and NMR elucidated their structure. In DSC and 1H, 13C-NMR spectral comparism showed the polysaccharides crystal of boiling alkaline extracts were more tight and regulation. The DSC and NMR spectrum showed functional group of sugar from water extracts of heating to boiling for 2 hours polysaccharides was lowest, but the absorbance peak markedly. The exothermic behaviors of water extracts of heating to boiling for 2 hours polysaccharides were examined by DSC, so supposition it impure. It could be study their physiological activities, advance analysis. For the application in healthy food, further research on the mechanism of polysaccharide properties is in progress.
Considering these studies, the major components in L. chinense were carbohydrates and fibers; methanolic extracts from L. chinense in the antioxidant activity better than water extracts. No toxicity or mutagenicity in S. typhimurium TA97, TA98, TA100 and TA 102. Both boiling water and alkaline extracts contain small molecular polysaccharide, and similar monosaccharide components.
Keyword: Lycium chinense, antioxidant properties, antimutagenic properties, polysaccharides, structural analysis
URI: http://hdl.handle.net/11455/51811
Appears in Collections:食品暨應用生物科技學系

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