Antioxidants are categorized in two major groups namely natural and synthetic. These groups are in dietary antioxidants intakes and play major roles in maintaining the homeostasis of the oxidative balance.
Natural antioxidants
Natural antioxidants are primarily phenolics that may occur in all parts of plants, such as fruits, vegetables, nuts, seeds, leaves, roots and barks. They scavenge harmful free radicals, which are implicated in the most common cancers and other degenerative diseases including poor brain function.
Tocopherols were one of the first liposoluble antioxidants isolated from plants. Due to their high concentration and habitual presence in vegetable oils, such as soybean or sunflower oil, Tocopherols are presented as the most common antioxidant in nature.
Natural antioxidant system is sorted in two major groups, enzymatic and non- enzymatic. Non-enzymatic antioxidants: Non-enzymatic antioxidants include direct acting antioxidants, which are extremely important in defense against oxidation stress. Non-enzymatic sources of antioxidants include vitamin C, vitamin E, selenium, zinc, beta carotene, carotene, taurine, hypotaurine, and glutathione.
Antioxidant enzymes are capable of stabilizing, or deactivating free radicals before they attack cellular components. They act by reducing the energy of the free radicals or by giving up some of their electrons for its use, thereby causing it to become stable. Enzymatic antioxidants include SOD, catalase, glutaredoxin, and glutathione reductase
Synthetic antioxidants
Synthetic antioxidants are chemically synthesized compounds since they do not occur in nature and are added to food as preservatives to help prevent lipid oxidation. Due to the non-protein nature, synthetic antioxidant compounds are relatively stable and usually able to penetrate the cells, and thus some of them can be administered orally.
Synthetic antioxidants are mainly phenolic, for example, butylated hydroxyanisole (BHA), butylated hydroxytoluene (BHT), tert-butyl hydroquinone (TBHQ) and gallates. BHA and BHT compounds are two phenolic antioxidants, capable of stabilizing free radicals by isolating them and preventing chain reactions. Both antioxidants are effective in animal fats, however, they are less effective in vegetable fats and oils.
Classification of antioxidants: Natural and Synthetic
