Thong Nguyen Minh, Vo Quan V, Huyen Trinh Le, Bay Mai Van, Tuan Dinh, Nam Pham Cam
The University of Danang, Campus in Kon Tum, 704 Phan Dinh Phung, Kon Tum 580000, Vietnam.
Quang Tri Teachers Training College, Quang Tri 520000, Vietnam.
ACS Omega. 2019 Sep 5;4(12):14996-15003. doi: 10.1021/acsomega.9b01780. eCollection 2019 Sep 17.
Radical-scavenging activity of isorhamnetin () and its diglycosides, named isorhamnetin-3,5'--β--diglucoside () and isorhamnetin-3,7--β--diglucoside () extracted from , has been studied through three main antioxidant pathways: hydrogen atom transfer (HAT), single electron transfer followed by proton transfer, and sequential proton loss electron transfer (SPLET). All thermodynamic parameters related to these radical-scavenging mechanisms were computed at the B3LYP/6-311G(d,p) level of theory both in the gas phase and in solution. The results suggest that HAT is the predominant mechanism in the gas phase, while SPLET is supported in an aqueous environment. In addition, the stability of radicals has also been explored by electron spin density and intramolecular hydrogen bonding. The potential energy profiles and kinetic calculations for the reactions between the selected compounds and the CHOO radical were calculated at 298.15 K. Among all investigated, compound has the highest antioxidant activity with the lowest Gibbs free energy (-4.05 kcal/mol) and the highest hydrogen atom transfer rate constant (3.61 × 10 M s). Substitution of the OH and OMe groups by two glucoses at the 3 and 5' sites of isorhamnetin has a significant impact on its antioxidant activity.
异鼠李素（）及其二糖苷（分别命名为异鼠李素-3,5'-β-二葡萄糖苷（）和异鼠李素-3,7-β-二葡萄糖苷（））从[具体来源未给出]中提取后，通过三种主要的抗氧化途径：氢原子转移（HAT）、单电子转移后质子转移以及连续质子丢失电子转移（SPLET），对其自由基清除活性进行了研究。在气相和溶液中，均在B3LYP/6-311G(d,p)理论水平下计算了与这些自由基清除机制相关的所有热力学参数。结果表明，HAT在气相中是主要机制，而在水环境中SPLET占主导。此外，还通过电子自旋密度和分子内氢键对自由基的稳定性进行了探索。在298.15 K下计算了所选化合物与CHOO自由基之间反应的势能剖面和动力学。在所有研究的化合物中，化合物具有最高的抗氧化活性，其吉布斯自由能最低（-4.05 kcal/mol），氢原子转移速率常数最高（3.61×10 M s）。在异鼠李素的3位和5'位用两个葡萄糖取代OH和OMe基团对其抗氧化活性有显著影响。
