sentence: structure of proanthocyanidins distribution in plants proanthocyanidins , including the lesser bioactive / bioavailable polymers ( 4 or more catechines ) represent a group of condensed flavan-3-ols , such as procyanidins , prodelphinidins and propelargonidins , that can be found in many plants , most notably apple , maritime pine bark , cinnamon , aronia fruit , cocoa bean , grape seed , grape skin ( procyanidins and prodelphinidin ) , and red wine of vitis vinifera ( the european wine grape ) .