Antioxidant Defence System

Several types of reactive species are generated in the body as a result of metabolic reactions in the form of free radicals .These species may be either oxygen derived or nitrogen derived and called prooxidants. They attack macromolecules including protein, DNA and lipid etc. causing cellular/tissue damage. To counter their effect, the body is endowed with another category of compounds called antioxidants. These antioxidants are produced either endogenously or received from exogenous sources and include enzymes like superoxide dismutase, catalase, glutathione peroxidase and glutathione reductase, minerals like Se, Mn, Cu and Zn, and vitamins like vitamin A, C and E. In a healthy body, prooxidants and antioxidants maintain a ratio and a shift in this ratio towards prooxidants gives rise to oxidative stress. Human antioxidant defenses have evolved to protect biological systems against oxidative stress, and a sophisticated cooperative array of antioxidant defense mechanisms is found in biological systems. The following article focuses on causes, role and conrol of oxidative stress in the development and progression of various human diseases.