Among the many ROS producers, the most important ones seem to be the NADPH oxidase (NOX) as the main superoxide producer [114], Xanthine oxidase (XO), that contributes to brain edema, and the intracellular enzymes such as COX lipoxygenases (LOXs), and cytochrome P450 that are involved in the arachidonic acid metabolism, a major superoxide source during ischemic stroke in the brain [76]. This evidence concerns the gene XDH and ischemic stroke.