Rutin, also called rutoside, quercetin-3-rutinoside and sophorin, is a citrus flavonoid glycoside found in buckwheat, the leaves Rutin27H30O162+, preventing it from binding to hydrogen peroxide, which would otherwise create a highly-reactive free-radical that may damage cells. It is also an antioxidant, and therefore plays a role in inhibiting some cancers.