ANTIOXIDANT ACTIVITY SCREENING MODELS AND THEIR MECHANISM: A REVIEW

An antioxidant is a material that at low concentrations delays or prevents oxidation of a substrate. Antioxidant compounds act throughout several chemical mechanisms: hydrogen atom transfer (HAT), single electron transfer (SET), and the potential to chelate transition metals. The significance of antioxidant mechanisms is to understand the biological meaning of antioxidants, their possible uses, their production by organic synthesis or biotechnological methods, or for the standardization of the determination of antioxidant activity. In general, antioxidant molecules can react either by multiple mechanisms or by a predominant mechanism. The chemical structure of the antioxidant material allows understanding of the antioxidant reaction mechanism. This chapter reviews the in vitro antioxidant reaction mechanisms of organic compounds polyphenols, carotenoids, and vitamins C against free radicals (FR) and pro oxidant compounds under diverse conditions, as well as the most commonly used methods to evaluate the antioxidant activity of these compounds according to the mechanism involved in the reaction with free radicals and the methods of in vitro antioxidant evaluation that are used commonly depending on the reaction mechanism of the antioxidant.