Quenching of Reactive Oxygen by Lycopene

Oxidative stress may be defined as that state in which exposure to free radicals or other oxidants represent a challenge to normal function, or even to survival. Such situations may arise from an increase in exposure to radicals/oxidants or may be the result of a decreased antioxidant capacity. 

A radical is defined as an atom or group of atoms with an unpaired electron. Because free radicals are missing an electron in their outer shell, they are highly reactive, and in excess they can damage or kill cells in culture or cause lesions in an organism. The formation of oxygen radicals and their metabolites is summarized as follows  

Therefore, the sequential addition of a single electron results in the formation of superoxide anion, hydrogen peroxide, hydroxyl radical, and water. 

Hydroxyl radicals ( OH) are the most damaging free radicals. Although they exist only for a fraction of a second, they are able to destroy vital enzymes, cause linking of DNA, unleash proteolytic enzymes, tear apart polysaccharides, and cause lipid peroxidation altering membrane permeability and associated functions. 

There are at least nine separate steps in which free radicals can be generated, which include the following items  

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