**1. Introduction**

Free radicals are produced during routine cellular metabolic processes. These free radicals are considered as important part of the pathological complications including diabetes mellitus, cardiovascular disorders, neurodegenerative disorders, cancer, cataracts, asthamatic conditions, rheumatoid arthritis, inflammatory conditions, intestinal complications, ischemic and postischemic conditions.

Antioxidants are those substances which at very low concentrations are capable of significantly reducing or preventing the oxidation of the substrates which can be oxidized are called as antioxidants. There is a highly complex system including enzymatic and non-enzymatic systems which is effective in synergistic way with each other, so as to protect the body cells and different organs from the damage caused b

free radicals. There are different types such as endogenous antioxidants and exogenous antioxidants such as the diet or various dietary supplements. There are different examples of dietary substances which actually do not scavenge the free radicals but they stimulate the endogenous activity ultimately categorized as antioxidants. An antioxidant which are considered as ideal, should easily absorbed and eliminate the free radicals and can able to cause chelation of redox metal ions at the levels which are considered as physiologically suitable. This should be active at the aqueous and/or in the membrane domains and can result in effective expression of gene at a positive direction. These endogenous antioxidants suppose to be highly potential in maintain the optimum cellular functioning and ultimately systemic healthy conditions and the well being also. But many a times, these endogenous antioxidants are considered as insufficient to support the oxidative or nitrosative stress, so along with it dietary antioxidants are important for maintain the highest cellular functioning. The highly potential enzymatic antioxidants consist of glutathione peroxidase, catalase, superoxide dismutase. Various examples in nonenzymatic antioxidants are vitamin C, vitamin E, thiol antioxidants including lipoic acid, glutathione etc., carotenoids, melatonins, flavanoids and other resembling compounds. One of the mechanisms called as antioxidant network, which involves the regeneration of the original properties of one antioxidant after interaction with other antioxidants. In various diseased conditions, it is reported that there is established link between the raised levels in ROS or RNS and deterioration of actions related to enzymatic or non enzymatic antioxidants [1–3].
