Coenzymes derived from riboflavin are also called flavins.
Flavins are critical for the metabolism of carbohydrates, fats, and proteins.
The glutathione redox cycle plays a major role in protecting organisms from reactive oxygen species , such as hydroperoxides. See diagram . Glutathione reductase requires FAD to regenerate two molecules of reduced glutathione from oxidized glutathione. Xanthine oxidase , another FAD-dependent enzyme, catalyzes the oxidation of hypoxanthine and xanthine to uric acid. Uric acid is one of the most effective water-soluble antioxidants in the blood.