@misc{oai:repo.qst.go.jp:00078936,
 author = {Nakanishi, Ikuo and Shoji, Yoshimi and Ohkubo, Kei and Ozawa, Toshihiko and Ken-ichiro, Matsumoto and Fukuzumi, Shunichi and Nakanishi, Ikuo and Shoji, Yoshimi and Ohkubo, Kei and Ozawa, Toshihiko and Matsumoto, Kenichiro},
 month = {Feb},
 note = {Hydrogen-atom transfer in the radical-scavenging reactions of antioxidants has attracted much attention with regard to quantum mechanical behaviors in biological reactions.  Recently, we have succeeded in solubilizing water-insoluble 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical in water using beta-cyclodextrin (beta-CD).  We report herein the kinetic isotope effect in the DPPH radical-scavenging reaction by antioxidants in an aqueous buffer solution.
Upon mixing of Trolox, a water-soluble analog of vitamin E, with the beta-CD-solubilized DPPH radical in a phosphate buffer solution (0.05 M, pH 7.0) at 298 K, the absorption band at 527 nm due to the DPPH radical immediately decreased.  From the time course change in the absorbance at 527 nm, the second-order rate constant (kH) for this reaction was determined to be 14000 M^-1 s^-1.  When H2O was replaced by D2O to prepare a phosphate buffer solution (0.05 M, pD 7.0), the second-order rate constant (kD) was significantly decreased to be 2000 M^-1 s^-1.  Thus, the kinetic isotope effect (kH/kD) of 7.4 was obtained, suggesting that tunneling may play a role in the hydrogen atom transfer from Trolox to the DPPH radical in a phosphate buffer solution., Oxygen Radicals, Gordon Research Conference},
 title = {Tunneling in the Scavenging Reaction of Water-Solubilized 2,2-Diphenyl-1-picrylhydrazyl Radical by Antioxidants in Aqueous Buffer Solutions},
 year = {2020}
}