Antioxidants for health and longevity

Abstract

Aging is an inevitable process due to functional and structural loss in the body accrued over a period of time owing to harmful effects of free radical generated by a variety of events. Aging is associated with changes in cell metabolism which leads to decrease in cell size, number, and atrophy of organs. Cell loss is most evident in the brain and heart, in which regeneration of lost cells does not occur. Many theories explain the process of aging, but the free radical theory provides plausible evidence for its occurrence. Endogenous metabolic events and exogenous factors are responsible for the generation of reactive oxygen species (ROS) and reactive nitrogen species (RNS). Reactive oxygen species is collectively used in a broad sense to free radicals like superoxide (O2.-), hydroxyl (OH•), and lipid peroxyl (LOO•) radicals and non-free radicals such as hydrogen peroxide (H2O2), ozone (O3), singlet oxygen (1O2), and lipid peroxide (LOOH). Uncontrolled increase in ROS concentration enhances free radical-mediated chain reactions which generally target proteins, lipids, polysaccharides, and DNA. Human body has the capability to counteract the ROS by enzymatic antioxidants superoxide dismutase (SOD), catalase, and glutathione peroxidase (GPx); nonenzymatic nutrient antioxidants β-carotene, α-tocopherol, ascorbic acid; and metabolic antioxidants, bilirubin, uric acid, ceruloplasmin, ferritin, transferrin, albumin, and glutathione.