Laboratory of Oxidative Stress Research

1. Elucidation of mechanisms of redox reaction due to reactive oxygenspecie and free radicals
2. Exploration of antioxidative components from natural substances

We, living organisms, receive many kind of stress (oxidative stress) from thesurrounding environment. For example, exposure of radiation and ultraviolet rays,absorption or suction of pollutant materials such as NOx, Sox, ClOx, DEP andasbestos, and chemical substance may induce the oxidative stress to living body, andthen the reactive oxygen species and free radicals are formed to initiate the trigger ofmany diseases (Fig. 1). We are now investigating the formation mechanism and

reactivity of these reactive oxygen and free radicals, and are developing thescavenging substances (antioxidants) for reactive oxygen and free radicals fromnatural substances in vitro and in vivo mainly by using electron spin resonance (ESR)spectroscopy. Until now, we have obtained the following results.

1. Establishment of quantitative generation method of superoxide (O2-), andexploration of scavenging compounds against superoxide and elucidation ofscavenging mechanism against superoxide.
2. Development of novel formation system of hydroxyl radical (HO・) such as thereaction system between copper(II)-ethylenediamine complex and hydrogenperoxide (H2O2).
3. Development of novel spin-trapping agents and their application to free radicals.
4. Exploitation of spin-trapping agents against nitric oxide (NO), and in vivo detectionand identification of NO by use of in vivo ESR (whole body measurement in livinganimals).
5. Exploration of generation method of peroxynittrite (ONOO-) and protectivecompounds against peroxynitrite.
6. Elucidation of involvement of reactive oxygen and free radicals in oxidative stressdue to whole body radiation exposure to mouse by use of in vivo ESR.
7. Development of novel spin probe which can permeate through blood-brain barrier,and in vivo ESR evaluation of influence of oxidative stress on brain by use of thisspin probe.
8. Elucidation of scavenging reactions and their mechanism of many kinds ofcatechin derivatives against reactive oxygen and free radicals.