Living cells continually generate free radicals or reactive oxygen species (ROS) through the respiratory chain during energetic metabolism. ROS can either be harmful or play important physiological roles in our body. Besides being produced during normal cell metabolism there are numerous exogenous factors, such as irradiation by UV light, X-rays, gamma-rays, and atmospheric pollutants which may...

Free radicals are species with one or more unpaired electrons. The unpaired electron results in a species that is often highly reactive. Free radicals have a wide range of reactions; two broad classes of reactions are electron transfer and addition reactions resulting in covalent bond formation. Free radicals can be classified as reducing (donating an electron to an acceptor) or oxidizing (acce...

We reviewed here the formation of free radicals and its effect physiologically. Studies mentioned above have indicated that free radical/ROS/RNS involvement in brain aging is direct as well as correlative. Increasing evidence demonstrates that accumulation of oxidation of DNA, proteins, and lipids by free radicals are responsible for the functional decline in aged brains. Also, lipid peroxidati...

Phagocytes mediate their innate immunological response by releasing products that damage invading microorganisms. These products include proteins such as lysozyme, peroxidases, and elastase as well as reactive oxygen species such as superoxide, hydrogen peroxide, hypohalous acid, and hydroxyl radical. Although it is clear that many phagocytic secretory products have direct cytotoxic potential, ...