洋葱醇提物总多酚含量及其抗氧化活性研究

Study on Total Polyphenol Content of the Ethanol Extract from Allium Cepa and Its Antioxidant Activity

目的建立洋葱醇提物总多酚含量测定方法和评价洋葱醇提物体外抗氧化活性。方法以没食子酸为标准品,采用福林酚法测定洋葱醇提物总多酚含量,采用2,2'-联氮双(3-乙基苯并噻唑啉-6-磺酸)二铵盐(ABTS)和1,1-二苯基-2-三硝基苯肼(DPPH)法评价洋葱醇提物的抗氧化活性。结果洋葱总多酚含量测定的最佳显色条件为显色温度60℃,显色时间60 min,福林酚体积0. 6 m L,10%碳酸钠体积0. 75 m L;没食子酸质量浓度在1. 2～5. 0 mg/L(R2=0. 999 5)范围内与吸光度值线性关系良好,平均回收率为113. 71%,RSD为3. 50%(n=6);洋葱总多酚平均含量为29. 908 8 mg/g,RSD为5. 169 4%(n=6);洋葱醇提物对ABTS自由基的半数抑制浓度(IC50)值为(187. 7±0. 08) mg/L,而阳性对照芦丁对ABTS和DPPH自由基的IC50值为(12. 87±0. 21) mg/L和(10. 29±0. 17)mg/L。结论该方法操作简便、灵敏度高且准确可靠,适合用于测定洋葱总多酚的含量。

Objective To establish a method for the determination of total polyphenol content(TPC)of the ethanol extract from Allium cepa and to evaluate the antioxidant activity in vitro of the ethanol extract from Allium cepa.Methods Gallic acid was used as the standard.The TPC of the ethanol extract from Allium cepa was determined by the Folin-Ciocalteu method.The antioxidant activity of the ethanolic extract from Allium cepa was evaluated by using ABTS and PPPH methods.Results The optimum conditions for the determination of TPC of Allium cepa were as follows:the chromogenic temperature was 60℃,the chromogenic time was 60 min,the volume of folin-ciocalteu was 0.6 mL,and the volume of 10%sodium carbonate solution was 0.75 mL.Gallic acid showed good linearity in the range of 1.2-5.0 mg/L(R^2=0.999 5),the average recovery rate was 113.71%with RSD of 3.50%(n=6).The average TPC of Allium cepa was 29.908 8 mg/g with RSD of 5.169 4%(n=6).The IC50 value of ethanolic extract from Allium cepa against ABTS free radical was(187.7±0.08)mg/L,while the IC50 values of positive control rutin against ABTS and DPPH free radicals were(12.87±0.21)mg/L and(10.29±0.17)mg/L.Conclusion The method is simple,sensitive,accurate and reliable,which is suitable for the determination of TPC of Allium cepa.