重陽木及火炭母草甲醇萃取物及其區分層之抗氧化性

Antioxidant Activity of Methanol Extracts and Subfractions from Bischofia javanica and Polygonum chinensis

劉宜珍(Yi-Chen Liu)

指導教授 ： 李綉鈴

大同大學/工程學院/生物工程學系所/碩士(2008年)

摘要

本研究分別以熱水、甲醇及乙酸乙酯萃取重陽木及火炭母草，並測定萃取物之抗氧化能力及其總酚、黃酮與縮合單寧之含量。結果顯示重陽木之甲醇萃取物具最高DPPH、ABTS與超氧陰離子自由基清除能力，其EC50 分別為 50.4 μg/ml、372.9 μg/ml及216.3 μg/ml。值得注意是其DPPH自由基清除能力與抗壞血酸相似，而其超氧陰離子自由基清除能力則遠高於抗壞血酸。甲醇萃取物亦具最高之還原力、螯合亞鐵離子能力及脂質過氧化抑制能力，其螯合亞鐵離子能力與抗壞血酸及BHA相似。進一步將重陽木甲醇萃取物經正己烷、乙醚、乙酸乙酯及正丁醇進行區分後，並評估五區分層之抗氧化能力，其中DPPH自由基清除能力以乙酸乙酯區分層及水層最佳，其EC50分別為48.5 μg/ml 與 46.7μg/ml，與抗壞血酸相似。乙酸乙酯區分層亦具有最高之ABTS自由基清除能力及超氧陰離子自由基清除能力與還原力，其中ABTS自由基清除能力與抗壞血酸及BHA相似，其EC50為219.4 μg/ml。正丁醇區分層則是具最高螯合亞鐵離子能力及脂質過氧化抑制能力。經皮爾森相關分析發現此抗氧化能力與總酚與縮合單寧含量呈高度正相關，但與黃酮含量並無顯著相關。
火炭母草三種萃取物中，以甲醇萃取物具最高之DPPH、ABTS、超氧陰離子自由基清除能力、還原力、螯合亞鐵離子能力及脂質過氧化抑制能力。其中螯合亞鐵離子能力約為55.9 μmol EDTA / g，與抗壞血酸及BHA相似。而，超氧陰離子自由基清除能力則顯著高於抗壞血酸，其EC50約為232.5 μg/ml。火炭母草甲醇萃取物經過正己烷、乙醚、乙酸乙酯及正丁醇進行區分並測定各區分層之其抗氧化能力，發現乙酸乙酯區分層具有最佳之DPPH、ABTS、超氧陰離子自由基清除能力、還原力，而螯合亞鐵離子能力及脂質過氧化抑制能力則以乙醚區分層最佳。乙酸乙酯區分層之 DPPH自由基清除能力及乙醚區分層之螯合亞鐵離子能力均與抗壞血酸及BHA相似，而五區分層之超氧陰離子自由基清除能力均比抗壞血酸高。經皮爾森相關分析發現此抗氧化能力與總酚、黃酮與縮合單寧含量呈高度正相關。

關鍵字

抗氧化性 ； 重陽木 ； 火炭母草

並列摘要

Bischofia javanica and Polygonum chinensis were extracted with boiling water, methanol and ethyl acetate, respectively, and their antioxidant activity, contents of total phenolic, flavonoids and condensed tannins were examined. The results showed that methanol extract of B. javanica demonstrated the highest scavenging activities against DPPH‧, ABTS‧+ and superoxide radicals with EC50 values of 50.4, 372.9 and 216.3 μg/ml, respectively. It was noteworthy that methanol extract exhibited similar activity to ascorbic acid in DPPH‧ scavenging activity, and significantly higher activity than ascorbic acid in superoxide radicals scavenging activity under experimental condition. The highest ferric reducing antioxidant power, ferrous ion chelating activity and inhibition of lipid peroxidation were also found in methanol extract. Surprisingly, ferric ion chelating activity of methanol extract was similar to those of ascorbic acid and BHA. Methanol extract of B. javanica was further partitioned sequentially with n-hexane, diethyl ether, ethyl acetate, and 1-butanol and then the antioxidant activity of each fraction was determined. Ethyl acetate and water fractions possessed the highest DPPH‧ scavenging activity with EC50 values of 48.5 μg/ml and 46.7 μg/ml, respectively, which was similar to that of ascorbic acid. Ethyl acetate fraction obtained the highest ABTS‧+ and superoxide anion radical scavenging activity as well as FRAP. It was noted that EC50 values of ABTS‧+ scavenging activity of ethyl acetate fraction was 219.4 μg/ml, similar to those of BHA and ascorbic acid. Nevertheless, 1-butanol fraction possessed the highest activity in ferrous ion-chelating activity and inhibition of lipid peroxidation. The correlation coefficient from Pearson correlation analysis indicated a positive relation between antioxidant activity and contents of total phenolics and condensed tannins. However, correlation of antioxidant activity with content of flavonoids was not found.
Among three extracts, methanol extract of P. chinensis displayed the highest scavenging activities against DPPH‧, ABTS‧+ and superoxide radicals, FRAP, ferrous ion chelating activity, and inhibition of lipid peroxidation. It was noted that ferrous ion chelating activity in methanol extract with 55.9 μmol EDTA equivalents / g was similar to those of ascorbic acid and BHA. Moreover, superoxide anions radicals scavenging activity with EC50 values of 232.5 μg/ml was significantly higher than that of ascorbic acid. Methanol extract of P. chinensis was further partitioned sequentially with n-hexane, diethyl ether, ethyl acetate and 1-butanol and then the antioxidant activity of each fraction was determined. Ethyl acetate fraction of P. chinensis methanol extract exhibited the highest activities in DPPH‧, ABTS‧+ and superoxide radicals scavenging activities, and reducing power, but the highest ferrous ion-chelating activity and inhibition of lipid peroxidation activity was found in diethyl ether fraction. The DPPH‧ scavenging activity of ethyl acetate fraction and the ferrous ion-chelating activity of diethyl ether fraction were similar to those of ascorbic acid and BHA, but the superoxide anions radicals scavenging activities of all five fraction were significantly higher than that of ascorbic acid. The contents of total phenolics, flavonoids and condensed tannins gave the strong positive correlations with antioxidant activities by Pearson correlation analysis.

並列關鍵字

Antioxidant Activity ； Bischofia javanica ； Polygonum chinensis

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