(also quercetin-3-rutinoside), an organic compound of the flavonoid group. Its molecule is formed of the flavone quer-cetin and the disaccharide rutinose. Rutin is contained in tea leaves and the leaves of the common rue; it is also contained in buckwheat and other plants. The compound possesses vitamin activity; it regulates the permeability of the capillaries. Rutin is used as a medicinal preparation, often together with ascorbic acid.