Compounds called anthocyanins, which are colored flavonoids, are water-soluble pigments that create the blue, purple, and red colors in plants. They are found in beans, fruits, vegetables and red wines; we eat them regularly as part of a healthy diet. They also happen to be powerful antioxidants.
Scientists sought to determine how these natural antioxidizing compounds might protect us from free radical damage. They learned that certain types of anthocyanins show significant free radical scavenging activity. Researchers concluded that anthocyanins exhibit interesting antioxidant properties, and could therefore represent a promising class of compounds useful in the treatment of pathologies where free radical production plays a key role. Source: Cell Biology Toxicology 2003 Aug;19(4):243-52.