ChEBI: Procyanidin B8 is a proanthocyanidin that is (+)-catechin and (-)-epicatechin units joined by a bond between positions 4 and 6' respectively in an alpha-configuration. Procyanidin B8 is found in acorn and is present in fruit and leaves of blackberry (Rubus fruticosus), raspberry (Rubus idaeus) and cowberry (Vaccinium vitis idaea). It can be also found in grape seeds and in beer. It has a role as a metabolite. It is a hydroxyflavan, a proanthocyanidin, a biflavonoid and a polyphenol. It is functionally related to a (-)-epicatechin and a (+)-catechin.