ABSTRACT
Antioxidants are substances that protect the cells in an organism from damage against the destructive tendencies of reactive species. They act by preventing oxidation of important macromolecules through many mecha-nisms such as scavenging or chelation of toxic radicals. Antioxidants can be grouped as either enzymatic antioxidants (superoxide dismutase, catalase (CAT), and glutathione peroxidase (GPX)) or nonenzymatic antioxidants (glutathione (GSH), vitamins C, E, ubiquinones, carotenoids, β-carotene, lycopene, polyphenols, uric acid, and mineral antioxidants: zinc, copper, selenium). Antioxidants can also be grouped according to its line of defense. Those in the first line of defense include GSH, superoxide dismutase (SOD), and CAT, while the linebackers or second line of defense are vitamins A, C, D, and E. The third line of defense is the carotenoids, the bioflavonoid, and coenzyme Q10. This chapter discusses antioxidants, their functions, mechanisms, and types.
