Epigenetic dysregulation has been noted to induce a variety of diseases. However, the mechanism by which this dysregulation occurs remains unclear. We have previously found that DNA methyltransferase, which catalyzes cytosine methylation, is selectively oxidized by several stresses; Oxidative modification results in the suppression of its enzymatic activity, suggesting that this reaction may be associated with epigenetics. In this study, we attempted to isolate a chemical compound that prevents this oxidation. Via in silico screening from a library of approximately 4,200,000 compounds, we could identify several candidates. A compound is effective at low concentrations below 1 microM. In addition, this chemical was no effect on enzyme activity. Therefore, it is suggested that this candidate has the function to effectively prevent oxidative modification. We are now investigating the effects of this compound on gene expression induced by oxidative stress and in vivo animal pathological models. In this symposium, we will introduce further pharmacological properties of this drug.