What is the Definition of Polyphenols?

Polyphenols are the compounds that contain an-ON group attached to the benzene ring. The main classes are: flavonoids, phenolic acids and polyphenols (tannins). They arise from common intermediates pllenylalanine or its precursor shikimic acid. Natural phenolic compounds range from simple ones like hydroxybenzoic acid to highly polymerized ones e.g. tannins. They arc glycosylated by one or more suga residues. The OH groups linked can be glucose, galactose, rhsunnose, xylose or arabinose, glucuronic or galacturonic acids.