Figure 2: Generation of reactive and damaging hydroxyl radicals (OH). Free Iron (Fe2+) reacts trough the Fenton reaction with hydrogen peroxide, leading to the generation of very reactive and damaging hydroxyl radicals (OH). Superoxide can also react with ferric iron in the Haber-Weiss reaction leading to the production of Fe2+, which then again affects redox cycling. The highly reactive hydroxyl radicals lead to oxidative stress-induced lipid peroxidation, mitochondrial dysfunction, and increase in intracellular free-calcium concentration, and finally causing neuronal death.