@misc{oai:repo.qst.go.jp:00070637,
 author = {Matsumoto, Kenichiro and Nakanishi, Ikuo and 松本 謙一郎 and 中西 郁夫},
 month = {Nov},
 note = {Hydroxyl radical (OH) is one of the most important players in oxidative stress. The OH can be measured using electron paramagnetic resonance (EPR) spin-trapping method. Generally, OH-scavenging-effect of an anti-oxidant has been estimated by a method adding the anti-oxidant and a spin-trapping agent to a OH generation system. X-ray irradiation to water can generate OH. In this simple system, estimation of the OH-scavenging-effect of an anti-oxidant can be much easier, while reduction of spin adduct with the anti-oxidant must be considered. In this study, we are trying to propose an efficient method for estimating OH-scavenging-effect of an anti-oxidant.
A reaction mixture containing 30 mM of a spin-trapping agent (DMPO) and an arbitrary concentration of an anti-oxidant was prepared using 100 mM phosphate buffer (pH7, containing 0.05 mM DTPA). X-ray was irradiated to the reaction mixture and then time course of the OH-spin-adduct (DMPO-OH) was measured immediately using X-band EPR spectrometer.
X-ray irradiation to the reaction mixture containing DMPO generates DMPO-OH in the reaction mixture dose dependently. Even doing the experiment under N2 gas atmosphere, no difference was obtained for amount of DMPO-OH generated compared to the experiment in the air. The DMPO-OH obtained in the reaction mixture was from OH generated by X-ray. When anti-oxidant type 1 was added to the reaction mixture, amount of X-ray induced DMPO-OH in the reaction mixture was decreased depending on the dose of the anti-oxidant type 1. To determine whether the anti-oxidant type 1 was really scavenging OH, the reduction rate of DMPO-OH after irradiation was estimated. The reduction rate of DMPO-OH by the anti-oxidant type 1 was enough slow; therefore, the reducing DMPO-OH amount by adding anti-oxidant before X-ray irradiation was mainly due to scavenging OH by the anti-oxidant type 1. Anti-oxidant type 2 also showed the reducing DMPO-OH amount, when the anti-oxidant type 2 was added to reaction mixture before X-ray irradiation. Anti-oxidant type 2, however, showed a rapid reduction of DMPO-OH after stopping X-ray irradiation. Scavenging OH by anti-oxidant 2 can not estimated directly from the result of the experiment; however, it is possible to think that anti-oxidant 2 was a strong reductant which can be reduce relatively stable nitroxyl radical (DMPO-OH in this case). Using the method in this experiment, anti-oxidative property can be estimated using scavenging OH and/or reducing DMPO-OH., 18th Annual Meeting of the Society for Free Radical Biology and Medicine},
 title = {Efficient Method for Hydroxyl Radical Scavenging Activity of Antioxidants},
 year = {2011}
}