Öz
In recent years, there has been a great deal of attention towards the free radical chemistry, exogenous antioxidants and phytochemicals and their safe use. Free radicals which cause oxidative stress, reactive oxygen and nitrogen species are produced by the body in various endogenous system. Apart from exposure to various physical and chemical conditions or pathological conditions can also be the source of oxidative stress. Under normal circumstances, between free radicals and antioxidants, there is a balance. It is necessary to live. Free radicals and antioxidant capability is exceeded reasonable limits encountered by oxidative stress in the body holds. Thus, lipids, proteins and DNA trigger damage reactions that lead to diseases can be occured. Therefore, the use of external antioxidants are frequently encountered in the prevention of oxidative stress. However, as in the example butylated hydroxytoluene (BHT) and butylated hydroxyanisole (BHA), it is understood that some synthetic antioxidants dangerous to health, the researchers tended to the effectively, non-toxic, natural, herbal antioxidative compounds. The review provides a brief overview on the basic characteristics and functional antioxidative roles of some phytochemicals.