||Comparison of Reactivity of Nitroxyl Free Radicals and Reactive Oxygen Species
Kamibayashi, Masato ,
Nyui, Minako ,
Nakanishi, Ikuo ,
Anzai, Kazunori ,
Ozawa, ToshihikoKen-ichiro, Matsumoto
Reactivity of nitroxyl free radicals and reactive oxygen species (ROS) were compared. In this presentation, 4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl (TEMPOL) and 3-carbamoyl-2,2,5,5-tetramethylpyrrolidine-N-oxyl (carbamoyl-PROXYL) were tested as typical 6-memberd ring and 5-memberd ring nitroxyl compounds. Two free radical species of ROS, i.e. hydroxyl radical (•OH) and superoxide (O2•-), were also subjected to an examination. The •OH was observed by UV irradiation to a H2O2 aqueous solution. The O2•- was obtained by a hypoxanthine-xanthine oxidase (HX-XO) reactive system. The molecular amount of ROS generated was quantified by electron spin resonance (EPR) spin-trapping method using 5-(2,2-dimethyl-1,3-propoxycyclophosphoryl)-5-methyl-1-pyrroline-N-oxide (CYPMPO) as the spin-trapping agent. Amount of •OH generation by H2O2-UV reaction system and amount of O2•- generation by HX-XO system were adjusted to become the same amount. O2•- was react with TEMPOL relatively easier compared to carbamoyl-PROXYL. TEMPOL has more reactive with O2•- than •OH, while carbamoyl-PROXYL was much reactive with •OH than O2•-. TEMPOL-H, which is the hydroxyl amine form of TEMPOL, was slightly more reactive with •OH then O2•-. Carbamoyl-PROXYL-H, the hydroxyl amine form of carbamoyl-PROXYL, has the similar reactivity with O2•- or with •OH.
1st QST International Symposium -Quantum Life Science-