@misc{oai:repo.qst.go.jp:00069222,
 author = {Nakanishi, Ikuo and Uto, Yoshihiro and Ohkubo, Kei and Nagasawa, Hideko and Hori, Hitoshi and Fukuzumi, Shunichi and Ozawa, Toshihiko and Anzai, Kazunori and et.al and 中西 郁夫 and 小澤 俊彦 and 安西 和紀},
 month = {Dec},
 note = {It is known that 2-methyl-6-phytylhydroquinone (2-MePHQ) and 2,3-dimethyl-6-phytylhydroquinone (2,3-Me2PHQ) are formed as precursors in the biosynthetic process of vitamin E.  However, very little is known about the antioxidative activity of these vitamin E precursors. Thus, we examined the radical-scavenging reactions of 2-MePHQ, 2,3-Me2PHQ, and their synthetic analogues, 2,5-dimethyl-6-phytylhydroquinone (2,5-Me2PHQ) and 2,3,5-trimethyl-6- phytylhydroquinone (2,3,5-Me3PHQ).  2,2-Diphenyl-1-picrylhydrazul radical (DPPH) was efficiently scavenged by these four hydroquinones in deaerated ethanol (EtOH) at 298 K.  From the decay of the absorbance at 516 nm due to DPPH, the second-order rate constants (kobs) for DPPH-scavenging reactions by the hydroquinones were determined as 280 (2-MePHQ), 390 (2,3-Me2PHQ), 280 (2,5-Me2PHQ), and 410 M-1 s-1 (2,3,5-Me3PHQ) in deaerated EtOH at 298 K.  2,3,5-Me3PHQ and 2,3-Me2PHQ, which have a methyl group at the C-3 position, showed a stronger DPPH-scavenging activity than alpha-tocopherol (kobs = 370 M-1 s-1).  The detailed mechanism of the DPPH-scavenging reactions by the hydroquinones will also be discussed based on the kinetic and theoretical results obtained in this study., International Conference on Food Factors for Health Promotion (ICoFF2007)},
 title = {Radical-Scavenging Rates of Biosynthetic Precursors of Vitamin E and Their Acyclic Analogues},
 year = {2007}
}