Vo Quan V, Cam Nam Pham, Bay Mai Van, Minh Thong Nguyen, Hieu Le Trung, Mechler Adam
Institute of Research and Development, Duy Tan University Danang 550000 Vietnam
Department of Chemical Engineering, The University of Da Nang - University of Science and Technology Danang 550000 Vietnam.
RSC Adv. 2019 Dec 18;9(72):42020-42028. doi: 10.1039/c9ra08381b.
Oxidative stress is implicated in aging and aging-related diseases, including cancer. Prevention-focused health management approaches emphasize the importance of dietary antioxidants, which naturally draws attention to the antioxidant capacity of natural products. Several groups of plant-derived antioxidant compounds have been identified and their radical scavenging activity confirmed and measured; it has proven challenging, however, to link the experimentally determined activity quantitatively to a molecular mechanism of action. Based on our success with a computational approach, in this study, the methylperoxyl radical scavenging activity of 12 natural stilbenes was evaluated based on kinetic and thermodynamic calculations. The results suggest that for stilbenes hydrogen atom transfer (HAT) is a main mechanism for the ROO˙ radical scavenging in the gas. Assessing the role of substitutes on the antioxidant properties of stilbenes revealed that the presence of O-H groups in ring B can increase the antioxidant activity due to a decrease in the bond dissociation energy (BDE) of the O4'-H, while the replacement of a H atom in the O-H groups by a methyl group reduces the radical scavenging capacity. Among the studied compounds, astringin is a promising antioxidant with the low BDE(O-H) value (73.4 kcal mol) and the high rate constants (3.36 × 10, 4.11 × 10 and 9.31 × 10 M s in the gas phase, pentyl ethanoate and water, respectively) that suggest higher activity than -resveratrol.
氧化应激与衰老及包括癌症在内的衰老相关疾病有关。以预防为重点的健康管理方法强调膳食抗氧化剂的重要性，这自然会让人关注天然产物的抗氧化能力。已鉴定出几类植物源抗氧化化合物，并证实和测量了它们的自由基清除活性；然而，要将实验测定的活性与分子作用机制进行定量关联已证明具有挑战性。基于我们在计算方法方面的成功，在本研究中，基于动力学和热力学计算评估了12种天然芪类化合物的甲基过氧自由基清除活性。结果表明，对于芪类化合物，氢原子转移（HAT）是气相中ROO˙自由基清除的主要机制。评估取代基对芪类化合物抗氧化性能的作用表明，B环中O-H基团的存在可由于O4'-H的键解离能（BDE）降低而增加抗氧化活性，而O-H基团中的一个H原子被甲基取代会降低自由基清除能力。在所研究的化合物中，紫杉叶素是一种有前景的抗氧化剂，其BDE（O-H）值较低（73.4 kcal/mol），速率常数较高（在气相、乙酸戊酯和水中分别为3.36×10、4.11×10和9.31×10 M-1s-1），表明其活性高于白藜芦醇。
