In this study, we investigated the antioxidant activity of $Pycnogenol^®$ and Ulmus macrocarpa extract. $Pycnogenol^®$ is proprietary extract of the bark of the French maritime pine tree (Pinus maritime). The Extracts from the bark of pine have been used in the past in different parts of the world in traditional medicine and are believed to affect various pathologies raging from vascular disease to arthritis. Ulmus macrocarpa is a deciduous tree which is distributed in Asia-temperate regions and the stem and root bark have been used in oriental traditional medicine for treatment of oedema, mastitis, gastric cancer and inflammation. Both Pycnogenol and Ulmus macrocarpa extract inhibited the deoxyribose degradation by hydroxyl radical and also inhibited NBT reduction by superoxide anion in vitro. But both didn``t scavenge hydrogen peroxide. Both $Pycnogenol^®$ and Ulmus macrocarpa extract protected the single-strand breaks in the plasmid DNA by Fe(II) and H2O2, and also by xanthine oxidase /hypoxanthine. But $Pycnogenol^®$ protected only up to 25㎍/ml whereas over 25㎍/ml of this showed the prooxidant activity. $Pycnogenol^®$ and Ulmus macrocarpa extract inhibited Fe(II) autooxidation and increased the Fe(III) reduction. $Pycnogenol^®$ showed more stronger prooxidant activity converting Fe(III) to Fe(II) than Ulmus macrocarpa extract. We also observed $Pycnogenol^®$ and Ulmus macrocarpa extract could protect the isolated plasmid DNA through chelating Fe(II) ions.