@misc{oai:repo.qst.go.jp:00071432,
 author = {和氣, 司 and 中西, 郁夫 and 大久保, 敬 and 福住, 俊一 and 小澤, 俊彦 and 松本, 謙一郎 and 鎌田, 正 and 和氣 司 and 中西 郁夫 and 大久保 敬 and 小澤 俊彦 and 松本 謙一郎 and 鎌田 正},
 month = {Mar},
 note = {The 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical, frequently used as a model of reactive oxygen species, is enough stable not to undergo self-reactions.  On the other hand, we have reported that redox-inactive metal ions affect the DPPH radical-scavenging activity of antioxidants.  These results imply that metal ions with Lewis acidity may affect the reactivity of DPPH radical itself.  Therefore, in this study we investigated the effect of aluminum ion on the reactivity of DPPH radical.  The effect of aluminum ion was evaluated using photometric titration.  After 30 min reactions of various concentrations of aluminum ion with DPPH radical at 37 °C, the absorption band at 517 nm due to DPPH radical was decreased and the band at 380 nm due to DPPH cation was observed appeared in acetonitrile.  This indicates that aluminum ion catalyzed the electron-transfer disproportionation of DPPH radical in acetonitrile.  The plot of absorbance at 517 nm vs [aluminum ion] showed an inflection point.  The scavenging activity (SA)-value was calculated as the ratio of the initial DPPH radical concentration to the aluminum ion concentration at the inflection point (Waki T, et al. Chem. Commun. 2013; 49: 9842-9844).  The SA value of aluminum ion (3.71) was significantly higher than that of Trolox (2.44).  Thus, the metal ions with a strong Lewis acidity themselves can act as free radical-scavengers., 17th Biennial Meeting of Society for Free Radical Research International (SFRRI 2014)},
 title = {Metal Ions with Lewis Acidity Catalyze the Disproportionation of the 2,2-Diphenyl-1-picrylhydrazyl Radical in an Aprotic Medium},
 year = {2014}
}