The generation of reactive oxygen
DZNeP that include superoxide (O2?), hydroxyl radical (OH), and hydrogen peroxide (H2O2) is related to cell death, stress-responses, aging, and various diseases such as cancer, ischemia/reperfusion injury, and atherosclerosis [1], [2], [3] and [4]. H2O2 and other ROS can induce cell death at relatively high concentrations in many cell types [5], [6], [7], [8] and [9]. Recent observations suggest that lower concentrations of ROS are involved in inter-cellular communication and intra-cellular signaling in normal and pathological conditions [10], [11], [12] and [13]. Superoxide is rapidly converted by non-enzymatic dismutation or superoxide dismutase (SOD) into H2O2in vivo. Among the ROS, H2O2 is a ubiquitous molecule that is able to diffuse freely into membranes due to its nonpolar characteristics. H2O2 stimulates proliferation or enhances survival of a wide variety of cell types [14], [15] and [16]. Also, low concentrations of H2O2 stimulate endothelial migration as well as tube formation in an in vitro model of angiogenesis [17]. H2O2 initiates signals for mitochondrial translocation of Bax in
lymphocytes [18]. H2O2 may be used as a second messenger in the NF-κB signaling system, despite its cytotoxicity [19] and [20].
