The flavonoid rutin is a flavonol glycoside comprised of the flavonol quercetin (see Quercetin) and the disaccharide rutinose. Rutin is found in many plants, especially the buckwheat plant Fagopyrum esculentum Moench, the flour of which is used to make pancakes. Other rich dietary sources of rutin include black tea and apple peels.
Many, if not most, of rutin's possible activities can be accounted for, in part, by rutin's antioxidant activity. Rutin is a phenolic antioxidant and has been demonstrated to scavenge superoxide radicals. Rutin can chelate metal ions, such as ferrous cations. Ferrous cations are involved in the so-called Fenton reaction, which generates reactive oxygen species. Rutin may also modulate the respiratory burst of neutrophils. The in vivo antioxidant activity of rutin is most likely due to its aglycone quercetin, to which it is metabolized following ingestion. Although most studies show rutin to inhibit lipid peroxidation, a few studies do not. Rutin may also help maintain levels of the biological antioxidant reduced glutathione. Importantly, under certain conditions, rutin or its metabolite quercetin may become a pro-oxidant. For example, nitrosation of rutin/ quercetin may produce a pro-oxidant molecule that may have mutagenic potential.