Polyphenols are secondary plant metabolites that we consume daily. Most of these are derived from l-phenylalanine via the phenylpropanoid pathway.
Sensu stricto, polyphenols are characterized by the presence of at least two phenolic groups associated in more or less complex structures, generally of high molecular weight. However, simple phenols (also known as phenolic acids), which can be polyphenol precursors, are also considered to belong to this group.
The most commonly used definition for the term “polyphenol” should be used to define compounds derived solely from the shikimate/phenylpropanoid and/or the polyketide pathway biosynthesis, with more than one phenolic unit and without nitrogen-based functions”.