The molecule is a proanthocyanidin consisting of (-)-epicatechin and (+)-catechin units joined by a bond between positions 4 and 8' respectively in a beta-configuration.. Procyanidin B1 can be found in Cinnamomum verum (Ceylon cinnamon, in the rind, bark or cortex), in Uncaria guianensis (cat's claw, in the root), and in Vitis vinifera (common grape vine, in the leaf) or in peach. It has a role as a metabolite, an EC 3.4.21.5 (thrombin) inhibitor and an anti-inflammatory agent. It is a hydroxyflavan, a proanthocyanidin, a biflavonoid and a polyphenol. It derives from a (-)-epicatechin and a (+)-catechin.
(2R,3S)-2-(3,4-dihydroxyphenyl)-8-[(2R,3R,4R)-2-(3,4-dihydroxyphenyl)-3,5,7-trihydroxy-3,4-dihydro-2H-chromen-4-yl]-3,4-dihydro-2H-chromene-3,5,7-triol