ABSTRACT
The general term free radical represents a molecule or atom having an unpaired electron, and reactive free radicals are those in which the electron is readily available to react with other molecules.Oxygen-derivedfreeradicalsthathavedrawntheinitialattentioninbiologyaresuperoxide (O2
i−), hydroxyl (•OH), peroxyl (ROO•), oxyl (RO•), singlet oxygen (1O2), and hydroperoxyl (HOO•) radicals.Thetermreactive oxygen species(ROS)wasmeanttodenotetheseradicalscollectively (Halliwell,1990;HalliwellandGutteridge,1993).Withthediscoveryofnitricoxide(NO)andits
22.1 Free Radicals: Intracellular Generation and Reactions ........................................................ 595 22.2Oxidative Stress and Antioxidants ....................................................................................... 597 22.3ClassiŸcation of Antioxidants ............................................................................................... 597 22.4Redox Reactions Involving Free Radicals ............................................................................ 598 22.5Radiation Chemistry in the Study of Free Radicals and Antioxidants ................................ 598 22.6 Redox Studies of Antioxidants by Pulse Radiolysis ............................................................. 601
22.6.1Phenolic Antioxidants ............................................................................................... 601 22.6.1.1Vitamin C and Vitamin E ..........................................................................603 22.6.1.2Water-Soluble Analogues of Vitamin E .....................................................605 22.6.1.3Flavonoids ..................................................................................................605 22.6.1.4 Resveratrol .................................................................................................608 22.6.1.5Curcumin ...................................................................................................608 22.6.1.6Folic Acid ...................................................................................................609
