Groupe de recherche en Biologie Végétale, Département de Chimie-Physique, Université du Québec à Trois-Rivières, C.P. 500, Trois-Rivières, Québec G9A 5H7, Canada.
J Photochem Photobiol B. 2013 Nov 5;128:43-9. doi: 10.1016/j.jphotobiol.2013.07.021. Epub 2013 Aug 20.
In this study, we report how the antioxidant capacities of major tea polyphenols are affected by their interactions with milk alpha-casein (milk protein) using three complimentary oxidation methods: ABTS(+) radical cation scavenging, cyclic voltammetry and lipid peroxidation inhibition. We found that using the ABTS(+) assays, the antioxidant activity of all polyphenols was lowered by 11-27% in the presence of caseins. Using cyclic voltammetry, the overall current measured at the electrode was decreased by the presence of the protein, from 21% to 61%. The peak potentials were also shifted to higher values varying from 13 to 41 mV. However, using lipid peroxidation method, we noticed of the antioxidant activity of all the polyphenols changed (from 6% up to 75%) after the addition of alpha-casein. The results show using this method the larger gallate esters containing polyphenols epicatechingallate (ECG) and (epigallocatechingallate (EGCG) were less affected by the presence of casein than smaller polyphenols catechins (C), epicatechin (EC) and epicgallocatechine (EGC). Alpha-casein caused a small effect on the chain breaking antioxidant capacity of theaflavins as well. Therefore, casein has different effects on the overall antioxidant capacities of tea compounds depending on the methods used. We aim to understand those results with the types of protein-polyphenol interactions that take place in various settings and their effects on the antioxidant capacities of those compounds.
在这项研究中，我们报告了主要茶多酚的抗氧化能力如何受到其与牛奶α-乳清蛋白（牛奶蛋白）相互作用的影响，使用了三种互补的氧化方法：ABTS(+)自由基阳离子清除、循环伏安法和脂质过氧化抑制。我们发现，使用 ABTS(+)测定法，在存在乳清蛋白的情况下，所有多酚的抗氧化活性都降低了 11-27%。使用循环伏安法，由于蛋白质的存在，电极上测量的总电流从 21%降低到 61%。峰电位也向更高值移动，从 13 到 41 mV 不等。然而，使用脂质过氧化方法，我们注意到所有多酚的抗氧化活性在添加α-乳清蛋白后发生了变化（从 6%到 75%）。结果表明，使用这种方法，含有较大没食子酸酯的多酚表儿茶素没食子酸酯（ECG）和（表没食子儿茶素没食子酸酯（EGCG）受乳清蛋白存在的影响小于较小的多酚儿茶素（C）、表儿茶素（EC）和表没食子儿茶素（EGC）。α-乳清蛋白对茶黄素的链断裂抗氧化能力也有较小的影响。因此，乳清蛋白对茶化合物的总抗氧化能力的影响取决于所使用的方法。我们旨在通过在各种环境中发生的蛋白质-多酚相互作用的类型及其对这些化合物抗氧化能力的影响来理解这些结果。
