Department of Food Science, University of Massachusetts, Chenoweth Laboratory, Amherst, Massachusetts 01003, United States.
J Agric Food Chem. 2012 Oct 17;60(41):10320-30. doi: 10.1021/jf302673j. Epub 2012 Oct 4.
Many antioxidants can interact to produce synergistic interactions that can more effectively inhibit lipid oxidation in foods. Esterification of rosmarinic acid produces a variety of compounds with different antioxidant activity due to differences in polarity and thus differences in partitioning in oil, water, and interfacial regions of oil-in-water emulsions (O/W). Therefore, rosmarinic acid and rosmarinate esters provide an interesting tool to study the ability of antioxidant to interact in O/W emulsions. In O/W emulsions, rosmarinic acid (R0) exhibited the strongest synergistic interaction with α-tocopherol while butyl (R4) and dodecyl (R12) rosmarinate esters exhibited small synergistic interaction and eicosyl rosmarinate esters (R20) exhibited slightly antagonistic interaction. Fluorescence quenching and electron paramagnetic resonance (EPR) studies showed that water-soluble rosmarinic acid (R0) exhibited more interactions with α-tocopherol than any of the tested esters (R4, R12, R20). This was also confirmed in O/W emulsions where R0 altered the formation of α-tocopherol quinone and α-tocopherol increased the formation of caffeic acid from R0. This formation of caffeic acid was proposed to be responsible for the synergistic activity of R0 and α-tocopherol since the formation of an additional antioxidant could further increase the oxidative stability of the emulsion.
许多抗氧化剂可以相互作用产生协同作用，从而更有效地抑制食品中的脂质氧化。迷迭香酸的酯化会产生各种具有不同抗氧化活性的化合物，这是由于极性的差异，从而导致在油、水和油包水乳状液（O/W）的界面区域中的分配不同。因此，迷迭香酸和迷迭香酸酯为研究抗氧化剂在 O/W 乳状液中相互作用的能力提供了一个有趣的工具。在 O/W 乳状液中，迷迭香酸（R0）与α-生育酚表现出最强的协同相互作用，而丁基（R4）和十二烷基（R12）迷迭香酸酯则表现出较小的协同相互作用，二十烷基（R20）迷迭香酸酯则表现出轻微的拮抗相互作用。荧光猝灭和电子顺磁共振（EPR）研究表明，水溶性迷迭香酸（R0）与α-生育酚的相互作用比任何测试的酯（R4、R12、R20）都要强。这在 O/W 乳状液中也得到了证实，其中 R0 改变了α-生育酚醌的形成，并且α-生育酚增加了 R0 生成咖啡酸的形成。由于形成了另一种抗氧化剂可以进一步提高乳液的氧化稳定性，因此推测这种咖啡酸的形成是 R0 和α-生育酚协同作用的原因。
