@misc{oai:repo.qst.go.jp:00071532,
 author = {和氣, 司 and 大久保, 敬 and 松本, 謙一郎 and 小澤, 俊彦 and 福住, 俊一 and 鎌田, 正 and 中西, 郁夫 and 和氣 司 and 大久保 敬 and 松本 謙一郎 and 小澤 俊彦 and 鎌田 正 and 中西 郁夫},
 month = {Nov},
 note = {Flavonoids are known to show an efficient scavenging activity against 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical as a model of reactive oxygen species.  However, little is known about the DPPH radical-scavenging mechanisms of flavonoids.  On the other hand, Lewis acids, such as Mg(2+) and Al(3+), are known to accelerate electron-transfer reactions.  In this study, we investigated the effect of Lewis acids on the radical-scavenging activity of flavonoids, as well as on their one-electron oxidation potentials (E(0)(ox)) to clarify the detailed radical-scavenging mechanisms.
The rate of the DPPH radical-scavenging reaction of kaempferol, one of flavonoids, in the presence or absence of 0.1 M Mg(ClO(4))(2) or Al(ClO(4))(3) were determined by monitoring the absorbance change at 517 nm due to DPPH radical.  The second-order rate constant (k) for the DPPH radical-scavenging reaction by kaempferol was decreased in the presence of the Lewis acid.  The E(0)(ox) value of kaempferol was determined by second-harmonic alternating current voltammeter.  Mg(2+) showed little effect on the E(0)(ox) value of kaempferol, while the E(0)(ox) value was largely shifted in the presence of Al(3+) to the positive direction.  On the other hand, Al(3+) significantly changed the cyclic voltammogram of DPPH radical, while a slight change was observed in the presence of Mg(2+).  These results indicate that the one-electron accepting ability of DPPH radical was significantly increased in the presence of Al(3+).  These results indicate that the DPPH radical-scavenging reaction of kaempferol occurred via a hydrogen-atom transfer as the rate-determining step rather than electron transfer., 第47回酸化反応討論会},
 title = {ルイス酸存在下におけるフラボノイド類の酸化反応挙動},
 year = {2014}
}