量研学術機関リポジトリ「QST-Repository」は、国立研究開発法人 量子科学技術研究開発機構に所属する職員等が生み出した学術成果（学会誌発表論文、学会発表、研究開発報告書、特許等）を集積しインターネット上で広く公開するサービスです。 Welcome to QST-Repository where we accumulates and discloses the academic research results(Journal Publications, Conference presentation, Research and Development Report, Patent, etc.) of the members of National Institutes for Quantum and Radiological Science and Technology.
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Since phenolic antioxidants, such as vitamin E (alpha-tocopherol) and catechins, are known to show both antioxidative and prooxidative activities under certain conditions, fine-tuning of such activities is of considerable importance to control oxidative stress induced by reactive oxygen species (ROS) in biological redox systems. However, very little is known about the structure-activity relationship of the phenolic antioxidants. In this study, we demonstrate that density functional theory (DFT) calculations of O-H bond dissociation enthalpies and ionization potentials (IP) of phenolic antioxidants are a powerful tool to expect their radical-scavenging activity. In fact, the logarithms of the second-order rate constants (k) for the scavenging reaction of galvinoxyl radical (GO) as an ROS model by various substituted 6-chromanols, which were synthesized as vitamin E analogues, in deaerated acetonitirile are found to correlate linearly with their IP values calculated by DFT. Among the derivatives, 8-amino-2,2-dimethylchroman-6-ol having the smallest IP value showed the highest GO-scavenging activity. Thus, the introduction of substituents, which lower the IP value, to the benzene ring of 6-chromanol results in the enhancement of the antioxidative activity of 6-chromanol derivatives.
Fine-Tuning of Redox Properties of Substituted 6-Chromanols as Vitamin E Analogues Based on Density Functional Theory Calculations
