Polyphenol

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Polyphenols are a group of chemical substances found in plants, characterized by the presence of more than one phenol group per molecule. Polyphenols are generally further categorized into tannins, lignins (phenylpropanoids), and flavonoids.

1 Chemistry
- 1.1 Classification and Nomenclature
2 In Foods
3 Health claims
4 See also
5 References

[edit] Chemistry

[edit] Classification and Nomenclature

The subdivision of polyphenols into tannins, lignins, and flavonoids is derived from the variety of simple polyphenolic units derived from secondary plant metabolism of the shikimate pathway as well as classical divisions based upon the relative importance of each base component to different fields of study. Tannin chemistry originated in the importance of the eponymously named tannic acid to the tanning industry; lignins to the chemistry of soil and plant structure; and flavonoids to the chemistry of plant secondary metabolites for plant defense, and flower color (e.g. from anthocyanins).

Base Unit:	Gallic Acid	flavone	cinnamic acid
Class/Polymer:	hydrolyzable tannin	flavonoid,condensed tannin	lignin (phenylpropanoid)

Polyphenols are also grouped and classified by the type and number of phenolic subcomponents present. More than one subcomponent can be present on a given polyphenol.

			phloroglucinol
phenol	pyrocatechol	pyrogallol	phloroglucinol
examples: coumaric acid derived lignins, kaempferol	examples: catechin, quercetin, caffeic and ferulic acid derived lignins	examples: gallocatechins (EGCG), tannins, myricetin	examples: almost all flavonoids

The phenolic unit can often be esterified or methylated. It can also be found dimerized or further polymerized, creating a new class of polyphenol. For example, ellagic acid is a dimer of gallic acid and forms the class of ellagitannins, or a catechin and a gallocatechin can combine to form the red compound theaflavin, a process which also results in the large class of brown thearubigins in tea.

[edit] In Foods

Notable sources of polyphenols include berries, tea, wine, olive oil, chocolate/cocoa, pomegranates, walnuts, peanuts, yerba mate, and other fruits and vegetables.

High levels of polyphenols can generally be found in the fruit skins.

[edit] Health claims

see main article, polyphenol antioxidant

Research indicates that polyphenols may have antioxidant characteristics with potential health benefits. They may reduce the risk of cardiovascular disease and cancer.^[1]