Figure 1.

Sources of reactive oxygen species (ROS) and consequences of imbalance. Several sources of ROS exist endogenously which are balanced by natural anti-oxidant systems. In times of excess ROS production, such as following cerebral ischaemia/reperfusion, the balance of oxidants exceeds anti-oxidant protection. Excess ROS, in turn, result in apoptosis, inflammation, DNA damage, lipid peroxidation and protein denaturation—all of which contribute to and amplify signals leading to damage following stroke.