Antioxidants in Plants

Nowhere in living things is oxidative stress greater than in the photosynthesizing leaf of a green plant, which harvests energetic particles of sunlight, and uses them to split water molecules apart into hydrogen and oxygen atoms in order to make sugars. Leaves and other exposed plant parts are accordingly chock-full of antioxidant molecules that keep these high-energy reactions from damaging essential DNA and proteins. Among these plant antioxidants are the carotenoid pigments, including orange beta-carotene, yellow lutein and zeaxanthin, and the red lycopene that colors tomato fruits. Green chlorophyll itself is an antioxidant, as are vitamins C and E. Then there are thousands of different “phenolic” compounds built from rings of 6 carbon atoms, which play several roles in plant life, from pigmentation to antimicrobial duty to attracting and repelling animals. All fruits, vegetables, and grains probably contain at least a few kinds of phenolic compounds; and the more pigmented and astringent they are, the more they’re likely to be rich in phenolic antioxidants.