Polyphenol
![Plant-derived polyphenol, tannic acid, formed by esterification of ten equivalents of the phenylpropanoid-derived gallic acid to a monosaccharide (glucose) core from primary metabolism.](/Images/godic/202502/03/Tannic_acid.svg4803.png")
![Ellagic acid, a dimer of gallic acid, and a core-type 'component' of polyphenols](/Images/godic/202502/03/Ellagic_acid.svg4803.png")
![Raspberry ellagitannin, a tannin composed of 14 gallic acid units around a core of three units of glucose, with two gallic acids as simple esters, and the remaining 12 appearing in 6 ellagic acid-type units. Ester, ether, and biaryl linkages are present, see below.](/Images/godic/202502/03/Raspberry_ellagitannin4804.png")
![Theaflavin-3-gallate, a plant-derived polyphenol formed by esterification of two equivalents of gallic acid to a theaflavin core. Note: two of the phenolic hydroxyl groups required to meet the phenol-count criterion of the WBSSH definition points are engaged in ether linkages.](/Images/godic/202502/03/Theaflavin-3'-gallate4804.png")
Polyphenols (noun, pronunciation of the singular /pɒliˈfiːnəl/ or /pɒliˈfɛnəl/, also known as polyhydroxyphenols) are a structural class of mainly natural, but also synthetic or semisynthetic, organic chemicals characterized by the presence of large multiples of phenol structural units. The number and characteristics of these phenol structures underlie the unique physical, chemical, and biological (metabolic, toxic, therapeutic, etc.) properties of particular members of the class. Examples include tannic acid (image at right) and ellagitannin (image below). The historically important chemical class of tannins is a subset of the polyphenols.