Procyanidins bind proteins including pancreatic digestive enzymes via non-covalent interactions with the abundant hydroxy groups. Spectroscopic interrogation of protein structure in combination with molecular modeling indicated that the interaction of amylase with EGCG changes the conformation of the enzymes, thus reducing enzyme activity. Broccoli, green tea or grape seed extracts rich in flavon-3-ols, particularly EGCG, also inhibited cholinesterases, tyrosinase, α-amylase and α-glucosidase. Larger polymers such as hydrolysable and condensed tannins with more co-ordinated hydroxy groups bind proteins more efficiently than smaller molecules