Tang Xingzhu, Wang Lingling, Zhang Yajie, Sun Chaofan
College of Science, Northeast Forestry University, Harbin 150040, China.
College of Chemistry, Chemical Engineering and Resource Utilization, Northeast Forestry University, Harbin 150040, China; Key Laboratory of Forest Plant Ecology, Ministry of Education, Northeast Forestry University, Harbin 150040, China; Heilongjiang Provincial Key Laboratory of Ecological Utilization of Forestry-Based Active Substances, Northeast Forestry University, Harbin 150040, China.
Spectrochim Acta A Mol Biomol Spectrosc. 2025 Feb 15;327:125370. doi: 10.1016/j.saa.2024.125370. Epub 2024 Nov 2.
Antioxidant activity, as a topic of current interest, is discussed together with the excited state intramolecular proton transfer (ESIPT) process for three flavonoid derivatives, based on density functional theory (DFT)and time-dependent DFT (TD-DFT) methods, as well as DPPH free radical scavenging assay. The potential energy curves and transition states demonstrate that the three molecules can undergo only single proton transfer in the excited state, and all of them are ultrafast ESIPT processes. The absorption spectra of all the molecules show effective protection against UV radiation with low fluorescence intensity, especially Baicalein (Bai), which demonstrates their great potential for sunscreen applications. The density of states, HOMO energy values, global and local indices reveal that the antioxidant activity of the molecules after ESIPT process is enhanced, with Bai having the highest antioxidant activity, which is significantly attributed to the number and position of phenolic hydroxyl groups. Moreover, by comparing the DPPH free radical scavenging activity under the dark and UV radiation conditions, the radical scavenging activity (RSA) value in the UV radiation is remarkably higher than that in the dark condition, in which Bai achieves RSA value of 93.4%. Overall, the antioxidant activity of all three ESIPT-based flavonoid derivatives, especially Bai, is significantly elevated in the keto* form, which reinforces the significant relationship between antioxidant activity and ESIPT process, and provides new application prospects for molecules with ESIPT properties.
作为当前备受关注的一个话题，基于密度泛函理论（DFT）和含时密度泛函理论（TD-DFT）方法以及DPPH自由基清除试验，对三种黄酮类衍生物的抗氧化活性与激发态分子内质子转移（ESIPT）过程进行了探讨。势能曲线和过渡态表明，这三种分子在激发态仅能发生单质子转移，且均为超快ESIPT过程。所有分子的吸收光谱显示出对紫外线辐射的有效防护且荧光强度较低，尤其是黄芩苷（Bai），这表明它们在防晒应用方面具有巨大潜力。态密度、最高占据分子轨道（HOMO）能量值、全局和局部指标表明，ESIPT过程后分子的抗氧化活性增强，其中Bai的抗氧化活性最高，这主要归因于酚羟基的数量和位置。此外，通过比较黑暗和紫外线辐射条件下的DPPH自由基清除活性，紫外线辐射下的自由基清除活性（RSA）值明显高于黑暗条件下，其中Bai的RSA值达到93.4%。总体而言，所有三种基于ESIPT的黄酮类衍生物，尤其是Bai，在酮*形式下的抗氧化活性显著提高，这加强了抗氧化活性与ESIPT过程之间的显著关系，并为具有ESIPT特性的分子提供了新的应用前景。
