电子顺磁共振波谱法测定三种类胡萝卜素抗氧化活性

运用电子顺磁共振波谱(EPR),通过三种类胡萝卜素(番茄红素、叶黄素、β-胡萝卜素)对1,1-二苯基-2-三硝基苯肼自由基(DPPH·)和羟基自由基(·OH)清除能力大小的比较,测定了三种类胡萝卜素抗氧化活性能力。结果表明,DPPH和Fe2+(固定Fe2+:H₂O₂=1:10)浓度均与EPR信号呈良好的线性关系,相关系数R2均大于0.99。三种类胡萝卜素对DPPH·和·OH均有一定清除作用,且随浓度的增大和时间的延长清除作用逐渐增强。其中,番茄红素的抗氧化活性能力最强,叶黄素次之,β-胡萝卜素最弱,浓度为0.6 mmol/L的番茄红素、叶黄素和β-胡萝卜素对DPPH·的清除率分别为95.4%、76.7%和47.7%,对·OH的清除率分别为56.6%、29.1%和14.0%。相较于紫外-可见分光光度(UV-Vis)法,该方法可以有效避免类胡萝卜素自身颜色对测试结果的干扰,研究结果可为完善类胡萝卜素等天然食品添加剂的抗氧化能力评价方法提供依据。

Determination of Antioxidant Activity of Three Kinds of Carotenoids by Electron Paramagnetic Resonance Spectroscopy

Electron paramagnetic resonance(EPR)technique was used to investigate the antioxidant activities of three carotenoids(lycopene,lutein,and β-carotene)by comparing their scavenging abilities against 1,1-diphenyl-2-picrylhydrazyl(DPPH·)and hydroxyl radical(·OH). The results showed that both DPPH and Fe2+(fixed Fe2+:H₂O₂=1:10)concentrations had a good linear relationship with the EPR signal,and the correlation coefficients R2 were greater than 0.99. The three kinds of carotenoids had certain scavenging effects on DPPH· and ·OH,and the scavenging ability increased with the increasing of concentration and time. Lycopene had the strongest antioxidant activity among the three carotenoids,and β-carotene had the weakest antioxidant activity. The scavenging values for DPPH· by lycopene,lutein and β-carotene with concentration of 0.6 mmol/L were 95.4%,76.7% and 47.7%,and for ·OH were 56.6%,29.1% and 14.0%,respectively. Compared with UV-visible spectrophotometry(UV-Vis),this method can avoid the color interference of carotenoid itself. These results provide information for improving the evaluation method of antioxidant capacity of such natural food additives.