大黃甲醇萃取物溶劑區分之抗氧化性質

Antioxidant Capacity-Guided Fractionation from Methanol Extract of Rhubarb

楊沐汪(Mu-Wang Yang)

指導教授 ： 李綉鈴

大同大學/工程學院/生物工程學系所/碩士(2007年)

摘要

大黃為蓼科植物多年草本生之根及根莖，為常用之中藥，具有治療便秘、抗發炎、抗菌等藥理性質。本研究探討不同溶劑對其抗氧化能力之影響，並利用溶劑區分對大黃具抗氧化活性之成份進行初步分離。結果顯示以甲醇萃取大黃之萃取率最高，為38.7%。大黃熱水萃取物之DPPH 自由基清除力及還原力高於甲醇與乙醇萃取物。而亞鐵離子螯合力則以甲醇萃取物最佳，螯合 50 % 亞鐵離子能力濃度（EC50）為 29.85 mg/ ml。大黃甲醇萃取物經n-hexane、ethyl acetate、diethyl ether與1-butanol及水區分後，發現ethyl acetate區分層之DPPH自由基清除力和還原力為最高，其清除50 % DPPH自由基之濃度（EC50）為0.064 mg/ ml，而n-hexane之區分層螯合亞鐵離子力為最強，螯合 50 % 亞鐵離子能力濃度（EC50）為 3.09 mg/ ml。

關鍵字

還原力 ； DPPH ； 抗氧化 ； 唐古特大黃 ； 大黃 ； 亞鐵離子螯合力

並列摘要

Rhubarbs, rhizomes and roots of Rheum palmatum L., R. tanguticum Maxim., R. coreanum Nakai, and R. undulatum L.( Polygonaceae), were used as purgative agents and possessed antibacterial and anti-inflammatory effects in Chinese traditional medicine. The effects of solvent varieties on the antioxidant activity of rhubarbs and antioxidant capacity-guided fractionation were conducted in this study. The results showed that the extraction yield, ca. 38.7 %, was the highest when methanol was used as extraction solvent. The hot water extract showed the highest antioxidant activity in DPPH free radical scavenging activity and reducing power. However, methanol extract demonstrated the highest ferrous ion chelating activity. The efficient concentration of chelating 50% of ferrous ions (EC50) was 29.85 mg/ ml. Methanol extract was partitioned sequentially with n-hexane, diethyl ether, ethyl acetate, 1-butanol and water and then the antioxidant activity of each fraction was determined. The highest DPPH free radical scavenging activity and reducing power were shown in ethyl acetate fraction. The concentration of scavenging 50% of DPPH free radicals (EC50) of ethyl acetate fraction was 0.064 mg/ ml. On the other hand, the n-hexane fraction exhibited the highest ferrous ion chelating activity. The efficient concentration of chelating 50% of ferrous ions (EC50) of n-hexane fraction was 3.09 mg/ ml.

並列關鍵字

reducing power ； DPPH ； antioxidant ； Rheum tanguticum ； Rhubarb ； ferrous ion chelating activity

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rhubarb are potent inhibitors of squalene epoxidase, a key enzyme in