著作: Ueno Megumi/Nyui Minako/Nakanishi Ikuo/Anzai Kazunori/Ozawa Toshihiko/Matsumoto Ken-ichiro/[宇都 義浩]/Scavenging of reactive oxygen species induced by hyperthermia in biological fluid/[Journal of Clinical Biochemistry and Nutrition]
(英) Scavenging of reactive oxygen species induced by hyperthermia in biological fluid
(英) The scavenging activity of rat plasma against hyperthermia-induced reactive oxygen species was tested. The glutathione-dependent reduction of a nitroxyl radical, 4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl, which was restricted by adding superoxide dismutase or by deoxygenating the reaction mixture, was applied to an index of superoxide (O2 (·-)) generation. A reaction mixture containing 0.1 mM 4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl and 1 mM glutathione was prepared using 100 mM phosphate buffer containing 0.05 mM diethylenetriaminepentaacetic acid. The reaction mixture was kept in a screw-top vial and incubated in a water bath at 37 or 44°C. The time course of the electron paramagnetic resonance signal of 4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl in the reaction mixture was measured by an X-band EPR spectrometer (JEOL, Tokyo, Japan). When the same experiment was performed using rat plasma instead of 100 mM PB, the glutathione-dependent reduction of 4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl, i.e., generation of O2 (·-), was not obtained. Only the first-order decay reduction of 4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl, which indicates direct reduction of 4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl, was obtained in rat plasma. Adding 0.5% albumin to the phosphate buffer reaction mixture could almost completely inhibit O2 (·-) generation at 37°C. However, addition of 0.5% albumin could not inhibit O2 (·-) generation at 44°C, i.e., hyperthermic temperature. Ascorbic acid also showed inhibition of O2 (·-) generation by 0.01 mM at 37°C, but 0.02 mM or more could inhibit O2 (·-) generation at 44°C. A higher concentration of ascorbic acid showed first-order reduction, i.e., direct one-electron reduction, of 4-hydroxyl-2,2,6,6-tetramethylpiperidine-N-oxyl. Hyperthermia-induced O2 (·-) generation in rat plasma can be mostly inhibited by albumin and ascorbic acid in the plasma.
Journal of Clinical Biochemistry and Nutrition(日本酸化ストレス学会)
|年月日||必須||2014年 3月 1日|