Figure 1.

Chemical structures of some PAC monomers. Panel (A) shows the general chemical structure of flavan-3-ol monomers; Panel (B) shows a monomer of propelagordin, procyanidin, and prodelphinidin, which differ from each other in regard to the number and/or position of hydroxyl groups on the B-ring; Panel (C) shows the chemical structure of catechin and epicatechin, along with the respective enantiomers, which are different from each other in regard to the stereochemistry of flavonol heterocycle.