 Particularly in the flavone-derived tannins, the base shown must be (additionally) heavily hydroxylated and polymerized in order to give the high molecular weight polyphenol motif that characterizes tannins.Typically, tannin molecules require at least 12 hydroxyl groups and at least five phenyl groups to function as protein binders.Oligostilbenoids (oligo- or polystilbenes) are oligomeric forms of stilbenoids and constitute a class of tannins.