Antioxidants 1 Antioxidants Introduction The chemical systems , existing in living organisms produce unstable molecules /particles called oxidants or free radicals . These unstable molecules can be lethal to the biological function of the organism . The response to these free radicals is found in the form of antioxidants .These are substances that retard the breakdown of another substance by oxygen . Antioxidants such as vitamin C (ascorbic acid , butylated hydroxytoluene (BHT , and butylated hydroxyanisole (BHA ) are added to foods to prevent them from becoming sour through exposure to air .Endogenously produced , nutrients such as beta-carotene , vitamin C ,vitamin E , and selenium have been found to play the role of antioxidants . Studies have suggested that the antioxidants that occur naturally in fresh fruits and vegetables have a protective effect . For example , vitamin E and beta-carotene appear to protect cell membranes vitamin C removes free radicals from inside the cell .The Mechanism Cellular metabolism gives rise to ions called free radicals . These radicals play a crucial role in killing bacteria . Free radicals are not only by-products , but also play an important role in cell signal transduction , apoptosis and infection control (Bonnefoy M , Drai J ,Kostka T , 2002 . However , when the production of these radicals gets enhanced , the body stands the risk of damage to the biomolecules through pre-activated immune response . Consequently , the process of ageing is accelerated (Ansari , 1997 . Continuous Antioxidants 2 exposure to free radicals and other Reactive Oxygen Species (ROS )through external sources like sunlight , pollution and other forms of radiation and also endogenous generation leads to tissue injuries (Flora , 2007 . The exposure of the biological unit or system to free radicals damages the integrity of the cell . When a cell ‘s integrity or quality has been compromised , it may result in cancer-proliferated and uncontrolled increase in cell size and number- , heart disease and stroke . Tissue damage eventually leads to diseases like Atherosclerosis ,Diabetes , Cancer and Ageing and ultimately death (Flora , 2007 .According to Flora (2007 ,“Radicals of oxygen (superoxide anion ,hydroxyl radical , and peroxy- radicals , reactive non-radical oxygen species such as hydrogen peroxide and singlet oxygen , as well as carbon ,nitrogen , and sulfur radicals comprise the variety of reactive molecules that can cause damage to cell (p .2 .The body comprises of enzyme systems that destroy free radicals .However , the principal antioxidants are vitamin E , vitamin C ,n-acetylcysteine and -lipoic acid . Selenium , a trace metal , is also a part of this system that aids in proper antioxidant system functioning .A subtle balance needs to be maintained between the production of the ROS (Reactive Oxygen Species ) and the compensating Endogenous Antioxidant system (Willcox JK , Ash SL Catignani GL , 2004 . The antioxidant system generates antioxidants that neutralize the radical ions by lending an electron . However , these antioxidants are stable and the neutralization process doesn ‘t turn them into free radicals .Failure of the antioxidant system leads to oxidative stress resulting in cardiovascular disease , cancer , and other chronic diseases that account for a major portion of deaths Antioxidants 3 today (Willcox JK , Ash SL Catignani…