No.10（2015）7.Evaluation of counter-activity to eliminate superoxide anion and OH radical using ESR combined with radiolysis

Seiko Nakagawa, Masayuki Sekiguchi

An aqueous solution containing 5,5-dimethyl-1-pyrroline-N-oxide (DMPO) was set to the flowing system using a pump and irradiated with X-ray (voltage: 450 kV, current: 10 mA) in N₂O bubbling to produce OH radicals. OH radicals were trapped by DMPO and detected with ESR as the DMPO-OH adduct. The yield of DMPO-OH decreased along with the increase in quantity of anti-oxidants (p-coumaric acid, mannitol, and thymidine). The obtained relative reaction rates with the OH radical reasonably agreed with those previously obtained by pulse radiolysis. An aqueous solution containing sodium formate and 5-(2,2-dimethyl1,3-propoxy cyclophosphoryl)-5-methyl-1-pyrroline-N-oxide (CYPMPO) was irradiated with low-energy electron beam(voltage:250 kV, current:1 mA, velocity of the conver:60 m/min) to produce superoxide anion (O_2^-). O_2^- were trapped by CYPMPO and detected with ESR as the CYPMPO-HO₂ adduct. The yield of CYPMPO-HO₂ decreased along with the increase in quantity of added polyphenols (hydroquinone, catechol and caffeic acid).

Keywords
Spin- trapping ESR, Radiolysis, OH radical, Superoxide anion, Anti-oxidants

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