@article{oai:repo.qst.go.jp:00048534,
 author = {Kawashima, Tomonori and Manda, Sushma and Uto, Yoshihiro and Ohkubo, Kei and Hori, Hitoshi and Matsumoto, Kenichiro and Fukuhara, Kiyoshi and Ikota, Nobuo and Fukuzumi, Shunichi and Ozawa, Toshihiko and Anzai, Kazunori and Nakanishi, Ikuo and 川島 知憲 and Ｍａｎｄａ Ｓｕｓｈｍａ and 松本 謙一郎 and 中西 郁夫},
 issue = {8},
 journal = {Bulletin of the Chemical Society of Japan},
 month = {Aug},
 note = {The kinetics for the reaction of the 2,2-diphenyl-1-picrylhydrazyl (DPPH) radical with artepillin C, a prenylated phenylpropanoid found specifically in Brazilian propolis, and its analogues was examined in deaerated acetonitrile (MeCN) to shed light on the mechanism for the radical-scavenging reaction of phenolic antioxidants as well as on the structure-activity relationship.  Among the examined analogues, a compound having a catechol moiety is found to have the largest second-order rate constant (k) for the DPPH radical-scavenging reaction.  The deuterium kinetic isotope effect of 1.6 was observed for the DPPH radical-scavenging reaction of artepillin C in the presence of 0.13 M CD(3)OD or CH(3)OH in deaerated MeCN at 298 K.  The log k values were found to be linearly correlated with calculated energy difference values (D(HT), HT = hydrogen transfer) between the artepillin C analogues and the corresponding phenoxyl radicals, while such a linear correlation cannot be observed between the log k values and calculated ionization potentials (IP), D(HT) - IP, or experimental one-electron oxidation potentials of the artepillin C analogues.  These results together with a calculated structure of the transition state for the reaction between the artepillin C analogue and the DPPH radical suggest that the DPPH radical-scavenging reaction of the artepillin C analogues in deaerated MeCN proceeds via a one-step hydrogen-atom transfer from the phenolic OH group to the DPPH radical rather than an electron transfer followed by proton transfer.},
 pages = {877--883},
 title = {Kinetics and Mechanism for the Scavenging Reaction of the 2,2-Diphenyl-1-picrylhydrazyl Radical by Synthetic Artepillin C Analogues},
 volume = {85},
 year = {2012}
}