Air Pollution, Oxidative Stress, and Alzheimer's Disease

Table 1

Reactive Oxygen Species (ROS), Sources, and Defense Mechanisms [17–19, 22, 26].

ROS
Superoxide (O2^•−); Hydrogen peroxide (H2O2); Hydroxyl radical (^•OH); Peroxyl radicals (ROO^•); Alkoxyl radicals (RO^•); Organic hydroperoxides (ROOR'); Hypochlorous acid (HOCl); Peroxynitrite (ONOO−); Singlet oxygen (^1O2)
ROS sources
Endogenous; Mitochondria (byproducts of electron transport); oxidases (Oxidase-catalyzed reactions); Inflammation (neutrophils, macrophages); Cytochrome P450 reactions; Arginine metabolism; Peroxisomal fatty acid metabolism (peroxisomes, lipoxygenases); Exogenous; Ionizing radiation (X–, γ−, UV); Chemotherapeutics; Inflammatory cytokines (macrophages, neutrophils); Environmental toxins
Antioxidant defense mechanisms
Enzymatic systems; Catalase (CAT); Superoxide dismutase (SOD); Glutathione peroxidase (GPx); Nonenzymatic systems; DNA repair mechanisms; Glutathione; Vitamins (A,C, and E); Carotenes