Antioxidative and radioprotective effects of edaravone

エダラボンによる抗酸化作用及び放射線防護作用

端 邦樹 ; 漆原 あゆみ; Lin, M.; 室屋 裕佐*; 山下 真一; 横谷 明徳; Fu, H. Y.*; 勝村 庸介*

Hata, Kuniki; Urushibara, Ayumi; Lin, M.; Muroya, Yusa*; Yamashita, Shinichi; Yokoya, Akinari; Fu, H. Y.*; Katsumura, Yosuke*

In order to study antioxidative mechanism of edaravone, 3-methyl-1-phenyl-2-pyrazolin-5-one, in aqueous solution, pulse radiolysis study on reactions of edaravone and its derivative, 1,3-dimethyl-2-pyrazolin-5-one, with OH radical and with N radical was carried out. The transient spectrum observed after the reaction with OH radical has a strong peak at 320 nm while that for the reaction with N radical has absorption bands not only at 345 but also at 800 nm. Unlike previous reports, this difference shows that different transient radicals would be produced, and OH adducts are probably generated in the former reaction. In contrast, two transient spectra observed after the reactions of the edaravone derivative with OH radical and with N radical are similar to each other. Thus, it is indicated that OH radical mainly adds to the phenyl group of edaravone. In addition, rate constant of the reaction of edaravone with OH radical was determined to be 8.5 10 dm mol s, which is almost independent on pH. This fact indicates that acidic dissociation of the pyrazolone ring of edaravone, of which pKa value is 7.0, does not affect the reactivity of edaravone with OH radical, supporting the abovementioned deduction that OH would add onto the phenyl group of edaravone. Protection of plasmid DNA by edaravone was measured using biochemical technique.