Wang Lei, Sun Chaofan, Wang Lingling
College of Science, Northeast Forestry University, Harbin 150040, China.
College of Chemistry, Chemical Engineering and Resource Utilization, Northeast Forestry University, Harbin 150040, China.
Antioxidants (Basel). 2025 May 25;14(6):633. doi: 10.3390/antiox14060633.
The impact of photoisomerization on antioxidant properties holds significant implications for fields such as medicine, chemistry, and consumer products. This investigation employs multistate complete active space second-order perturbation theory (MS-CASPT2), complemented by density functional theory (DFT) and time-dependent DFT (TD-DFT) methods, to examine the photoisomerization behavior of sinapic acid (SA) and methyl sinapate (MS) under ultraviolet (UV) irradiation, while systematically analyzing their antioxidant properties in the S state. The computational results, validated by two independent theoretical approaches, confirm that both SA and MS can undergo photoisomerization through conical intersection pathways, providing crucial insights into their non-radiative transition mechanisms. In the S state, cis-SA and cis-MS exhibit higher antioxidant activity, while in the S state, antioxidant performance is strongly solvent-dependent: trans-SA outperforms in ethyl acetate (Eac) and water, whereas cis-SA is more effective in methanol (MeOH). Notably, the natural population analysis (NPA) charges of all four compounds increase upon photoexcitation, suggesting that photoexcitation enhances antioxidant properties. This study addresses a critical gap in our understanding of the relationship between photoisomerization and antioxidant activity in natural phenolic compounds.
光异构化对抗氧化性能的影响在医学、化学和消费品等领域具有重要意义。本研究采用多态完全活性空间二阶微扰理论（MS-CASPT2），并辅以密度泛函理论（DFT）和含时密度泛函理论（TD-DFT）方法，研究了芥子酸（SA）和芥子酸甲酯（MS）在紫外（UV）照射下的光异构化行为，同时系统分析了它们在S态下的抗氧化性能。通过两种独立理论方法验证的计算结果证实，SA和MS均可通过锥形交叉途径发生光异构化，这为它们的非辐射跃迁机制提供了关键见解。在S态下，顺式SA和顺式MS表现出较高的抗氧化活性，而在S态下，抗氧化性能强烈依赖于溶剂：反式SA在乙酸乙酯（Eac）和水中表现更优，而顺式SA在甲醇（MeOH）中更有效。值得注意的是，所有四种化合物的自然布居分析（NPA）电荷在光激发后均增加，这表明光激发增强了抗氧化性能。本研究填补了我们在理解天然酚类化合物光异构化与抗氧化活性之间关系方面的关键空白。
