Apples contain an anti-inflammatory flavonoid called quercetin, while red wine contains the flavonoid catechin.
It contains two coloring principles, quercetrin and quercetin.
A very minute proportion of quercetin, a principle yielded by quercitron bark, has been obtained from catechu.
quercetin quer·ce·tin (kwûr'sĭ-tĭn)
A yellow powdered crystalline compound produced synthetically or occurring as a glycoside in the rind and bark of numerous plants, used medicinally to treat abnormal capillary fragility. Also called meletin.