Oxidative stress is mainly associated with an increased production of reactive oxygen species (ROS) such as free radicals and peroxides. It is now well attested that oxidative stress is one of the main mechanisms involved in the development of several disorders such as cancer, neurodegenerative, vascular, and heart diseases. Furthermore, it has been observed that a high intake of vegetables and fruits reduces the risk of developing these disorders, suggesting that dietary compounds might act as potent antioxidants .Consequently, the search for natural antioxidants and free radical scavengers represents a large part of natural products research, and rapid screening assays are therefore valuable. Many in vitro methods are currently available, and some of these can be applied to TLC for postchromatographic derivatization.