Quantitative elucidation of the molecular mechanisms of hydroxyl radical quenching reactivity of phenolic compounds.
Reported discrepancies have confused the understanding of the molecular mechanisms of antioxidant reactivity somewhat. The consequent problems necessitate systematic investigations on the molecular orbital features of antioxidants and their correlation with antioxidant potentials. In the present work, phenolic compounds as typical antioxidants were selected to investigate their hydroxyl radical-scavenging properties, and the related mechanisms of action were studied theoretically by computational chemistry. A good correlation was observed between antioxidant activity and theoretical parameters, such as O-H bond dissociation energy (BDE), ionization potential (IP), enthalpy of electron transfer (E(a)), chemical hardness (HOMO-LUMO gap), and spin delocalization of the phenoxyl radicals (D(s)(r)). The results demonstrate that the molecular mechanisms regulating the antioxidant action were more complex than hydrogen or electron-transfer processes and explain previous contradictions. Meanwhile, a satisfactory quantitative structure-activity relationship (QSAR) model was established which should be of predictive value in evaluating or screening hydroxyl radical-scavenging antioxidants.
Cheng
Zhiyong
Z
Department of Chemical Biology, College of Chemistry and Molecular Engineering, Peking University, Beijing 100871, China.
Ren
Jie
J
Yan
Guangtao
G
Li
Yuanzong
Y
Chang
Wenbao
W
Chen
Zhida
Z
D000975:Antioxidants / Q000737:chemistry*; D004579:Electron Transport; D006860:Hydrogen Bonding; D017665:Hydroxyl Radical / Q000737:chemistry*; D008163:Luminescent Measurements; D008956:Models, Chemical; D010636:Phenols / Q000737:chemistry*; D021281:Quantitative Structure-Activity Relationship; D017392:Thiobarbituric Acid Reactive Substances / Q000737:chemistry
D000975:Antioxidants; D010636:Phenols; D017392:Thiobarbituric Acid Reactive Substances; D017665:Hydroxyl Radical