title: Aluminium ion-promoted radical-scavenging reaction of methylated hydroquinone derivatives.
abstract: The effect of the aluminium ion (Al(3+)) on the scavenging reaction of a 2,2-diphenyl-1-picrylhydrazyl radical (DPPH˙), as a reactivity model of reactive oxygen species, with hydroquinone (QH2) and its methylated derivatives (MenQH2, n = 1-4) was investigated using stopped-flow and electrochemical techniques in a hydroalcoholic medium. The second-order rate constants (k) for the DPPH˙-scavenging reaction of the hydroquinones increased with the increasing number of methyl substituents. Upon addition of Al(3+), the k values significantly increased depending on the concentration of Al(3+). Such an accelerating effect of Al(3+) on the DPPH˙-scavenging rates of the hydroquinones results from the remarkable positive shift of the one-electron reduction potential (Ered) of DPPH˙ in the presence of Al(3+). These results demonstrate that Al(3+), a strong Lewis acid, can act as a radical-scavenging promoter by stabilising the one-electron reduced species of the radical, although Al(3+) is reported not only to act as a pro-oxidant but also to strongly interact with biomolecules, showing toxicities.
authors: Quantitative RedOx Sensing Team (QRST), Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Inage-ku, Chiba 263-8555, Japan. nakanishi.ikuo@qst.go.jp.
authors: Ikuo
authors: I
authors: Nakanishi
authors: Quantitative RedOx Sensing Team (QRST), Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Inage-ku, Chiba 263-8555, Japan. nakanishi.ikuo@qst.go.jp and Division of Applied Chemistry, Graduate School of Engineering, Osaka University, Suita, Osaka 565-0871, Japan and Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea.
authors: Kei
authors: K
authors: Ohkubo
authors: Quantitative RedOx Sensing Team (QRST), Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Inage-ku, Chiba 263-8555, Japan. nakanishi.ikuo@qst.go.jp and Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Chiba 263-8522, Japan.
authors: Yukihiro
authors: Y
authors: Ogawa
authors: Quantitative RedOx Sensing Team (QRST), Department of Basic Medical Sciences for Radiation Damages, National Institute of Radiological Sciences (NIRS), National Institutes for Quantum and Radiological Science and Technology (QST), Inage-ku, Chiba 263-8555, Japan. nakanishi.ikuo@qst.go.jp and Graduate School of Advanced Integration Science, Chiba University, Inage-ku, Chiba 263-8522, Japan.
authors: Ken-Ichiro
authors: K
authors: Matsumoto
authors: Division of Oxidative Stress Research, Showa Pharmaceutical University, Machida, Tokyo 194-8543, Japan.
authors: Toshihiko
authors: T
authors: Ozawa
authors: Department of Chemistry and Nano Science, Ewha Womans University, Seoul 120-750, Korea and Faculty of Science and Technology, Meijo University, SENTAN, Japan Science and Technology Agency (JST), Nagoya, Aichi 468-8502, Japan.
authors: Shunichi
authors: S
authors: Fukuzumi
mesh_terms: D000535:Aluminum / Q000737:chemistry*; D016166:Free Radical Scavengers / Q000737:chemistry*; D006873:Hydroquinones / Q000138:chemical synthesis* / Q000737:chemistry; D007477:Ions / Q000737:chemistry; D007700:Kinetics; D008745:Methylation; D015394:Molecular Structure
chemical_list: D016166:Free Radical Scavengers; D006873:Hydroquinones; D007477:Ions; D000535:Aluminum