State Key Laboratory of Organic-Inorganic Composites, Beijing University of Chemical Technology, Beijing 100029, PR China.
Department of Chemical Engineering, Tsinghua University, Beijing 100084, PR China.
Food Res Int. 2022 Oct;160:111760. doi: 10.1016/j.foodres.2022.111760. Epub 2022 Jul 30.
Polyphenol, though used as antioxidants in food industry, suffers from poor solubility issues in vegetable oil. Usually, its solubility would be enhanced through esterification. This work investigated the antioxidant activity and oxidative stability of caffeic acid (CA) and its derivative modified esters by molecular simulation and experiments. Density functional theory (DFT) and molecular dynamic analysis revealed the antioxidant mechanism of CA esters attributing to the comprehensive effects. The lower hydrogen dissociation energy (ΔG) of CA esters with catechol moiety caused the transformation of antioxidant into quinone via the double hydrogen atom transfer reaction. Particularly, the second reduced hydrogen dissociation energy was the keypoint. The strong non-bond energy and hydrogen bond allowed CA esters and oil molecules to interact more efficiently. Hence, the ester moieties enhanced the antioxidant activity with 4.5-6.5 % ΔG reduction compared to CA. Rancimat and DSC assays validated the theoretical predictions. This result shows that the antioxidant activity of CA and its esters could be predicted by this molecular simulation way, which may aid in designing of new polyphenol antioxidant structure.
多酚虽然被用作食品工业中的抗氧化剂，但在植物油中溶解度问题严重。通常，通过酯化可以提高其溶解度。本工作通过分子模拟和实验研究了咖啡酸（CA）及其衍生酯化改性物的抗氧化活性和氧化稳定性。密度泛函理论（DFT）和分子动力学分析揭示了 CA 酯的抗氧化机制归因于综合效应。具有邻苯二酚结构的 CA 酯的较低氢离解能（ΔG）导致抗氧化剂通过双氢原子转移反应转化为醌。特别是，第二次还原氢离解能是关键。较强的非键能和氢键使得 CA 酯和油分子能够更有效地相互作用。因此，与 CA 相比，酯基降低了 4.5-6.5%的ΔG，从而提高了抗氧化活性。加速氧化稳定性试验（Rancimat）和差示扫描量热法（DSC）验证了理论预测。结果表明，通过这种分子模拟方法可以预测 CA 及其酯类的抗氧化活性，这可能有助于设计新型多酚抗氧化剂结构。
