To adapt to their evolution from marine to terrestrial life, terrestrial plants began producing antioxidants not found in marine organisms, such as vitamin C, polyphenols, and tocopherols. Between 50 million and 200 million years ago, angiosperms evolved many natural antioxidant pigments-especially during the Jurassic period-as a chemical means to combat reactive oxygen species, byproducts of photosynthesis. Originally, the term "antioxidant" specifically referred to chemical substances that prevent oxygen depletion. In the late 19th and early 20th centuries, extensive research focused on the use of antioxidants in important industrial processes, such as preventing metal corrosion, rubber vulcanization, and the buildup in internal combustion engines caused by fuel polymerization.
Early biological research on antioxidants focused on how to use them to prevent rancidity caused by the oxidation of unsaturated fatty acids. Antioxidant activity could be measured by a simple method: placing a piece of fat in an oxygen-filled, sealed container and determining its oxidation rate. However, with the discovery and confirmation of vitamins A, C, and E, which have antioxidant properties, the importance of antioxidants in the biochemical processes of living organisms became apparent. Once it was recognized that substances with antioxidant activity may themselves be easily oxidized, the exploration of the possible mechanisms of action of antioxidants began. By studying how vitamin E prevents lipid peroxidation, it was clarified that antioxidants, as reducing agents, prevent cell damage by reacting with reactive oxygen species, thus achieving their antioxidant effect.
