Cano A, Acosta M, Arnao M B
Department of Plant Biology (Plant Physiology), University of Murcia, Spain.
Redox Rep. 2000;5(6):365-70. doi: 10.1179/135100000101535933.
The 2,2'-azino-bis-(3-ethylbenzthiazoline-6-sulphonic acid) radical (ABTS(.+)) can be generated by the enzymatic system formed by hydrogen peroxide and horseradish peroxidase in an organic medium. The ABTS radical is easily generated in acidified ethanol medium in about 100 s with a stability of 1.7 x 10(-3) (-deltaabs/min) monitored at 730 nm. Other organic solvents, such as methanol or acetone, have lower radical generation times but the radical is less stable. The addition of Trolox or a lipophilic antioxidant such as alpha-tocopherol or beta-carotene produces a decrease in absorbance that can be used to estimate antioxidant capacity. Using a spectrophotometric end-point method and microplate-reader equipment, we have developed a method that estimates the antioxidant activity of different lipophilic vitamins. The use of Trolox as an antioxidant standard led to a limit of detection of 0.08 nmoles and limit of quantitation of 0.28 nmoles, while similar values were obtained for alpha-tocopherol and beta-carotene. The relative antioxidant activity values obtained by different antioxidants showed that alpha-tocopherol has a similar antioxidant potential to Trolox and that beta-carotene has 2.6 times the antioxidant potential of Trolox. In our opinion, this method can be useful for estimating the antioxidant activity in lipophilic samples and as a complement to other methods that measure antioxidant activity in aqueous media.
2,2'-偶氮二(3-乙基苯并噻唑啉-6-磺酸)自由基(ABTS(·+))可由过氧化氢和辣根过氧化物酶在有机介质中形成的酶系统产生。在酸化乙醇介质中，ABTS自由基约100秒内即可轻松产生，在730纳米处监测其稳定性为1.7×10(-3)(-吸光度/分钟)。其他有机溶剂，如甲醇或丙酮，自由基产生时间较短，但自由基稳定性较差。添加Trolox或亲脂性抗氧化剂如α-生育酚或β-胡萝卜素会导致吸光度下降，可用于估计抗氧化能力。我们使用分光光度终点法和酶标仪设备，开发了一种估计不同亲脂性维生素抗氧化活性的方法。以Trolox作为抗氧化剂标准，检测限为0.08纳摩尔，定量限为0.28纳摩尔，α-生育酚和β-胡萝卜素也得到了类似的值。不同抗氧化剂获得的相对抗氧化活性值表明，α-生育酚具有与Trolox相似的抗氧化潜力，β-胡萝卜素的抗氧化潜力是Trolox的2.6倍。我们认为，该方法可用于估计亲脂性样品中的抗氧化活性，并作为测量水性介质中抗氧化活性的其他方法的补充。
