Polyphenols are a group of chemical substances found in plants, characterized by the presence of more than one phenol unit or building block per molecule. Polyphenols are generally divided into hydrolyzable tannins (gallic acid esters of glucose and other sugars) and phenylpropanoids, such as lignins, flavonoids, and condensed tannins. Image File history File links Mergefrom. ... Molecular structure of flavone, a common Polyphenol antioxidant Polyphenol antioxidant is a class of multi-phenolic compounds known for their role of down-regulating free radical formation in mammals . ... Phenol, also known under an older name of carbolic acid, is a colourless crystalline solid with a typical sweet tarry odor. ... Tannins are astringent, bitter-tasting plant polyphenols that bind and precipitate proteins. ... Chemical structure of gallic acid Gallic acid is an organic acid, also known as 3,4,5-trihydroxybenzoic acid, found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... Phenylpropanoids are a class of plant-derived organic compounds that are biosynthesized from the amino acid phenylalanine. ... Lignin (sometimes lignen) is a chemical compound (complex, highly cross-linked aromatic polymer) that is most commonly derived from wood and is an integral part of the cell walls of plants, especially in tracheids, xylem fibres and sclereids. ... Molecular structure of the flavone backbone (2-phenyl-1,4-benzopyrone) The term flavonoid refers to a class of plant secondary metabolites. ...

Chemistry

Classification and Nomenclature

The division 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^[1] 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 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). Shikimic acid, more commonly known as its anionic form shikimate, is an important biochemical intermediate in plants and microorganisms. ... This is a bottle of tannic acid. ... This article is about making hides into leather. ... Loess field in Germany Surface-water-gley developed in glacial till, Northern Ireland For the American hard rock band, see SOiL. For the System of a Down song, see Soil (song). ... Poison ivy produces urushiol to protect the plant from herbivores. ... Anthocyanin is a pigment that reflects the red to blue range of the visible spectrum. ...

The largest and best studied polyphenols are the flavonoids, which include several thousand compounds, among them the flavonols, flavones, catechins, flavanones, anthocyanidins, and isoflavonoids.^[2] Flavonols are a class of flavonoids that use the 3-hydroxyflavone backbone (3-hydroxy-2-phenylchromen-4-one (IUPAC)). Their diversity stems from the different positions the phenolic -OH groups. ... Molecular structure of the flavone backbone (2-phenylchromen-4-one / 2-phenyl-1-benzopyran-4-one) Flavones are a class of flavonoids based on the backbone of 2-phenylchromen-4-one (2-phenyl-1-benzopyran-4-one) shown on the right. ... Catechin is a bioflavonoid and a powerful anti-oxidant. ... Molecular structure of the flavone backbone (2-phenyl-1,4-benzopyrone) The term flavonoid refers to a class of plant secondary metabolites. ...

The most abundant polyphenols are the condensed tannins, found in virtually all families of plants, and comprising up to 50% of the dry weight of leaves. The convergent evolution of tannin-rich plant communities has occurred on nutrient-poor acidic soils throughout the world. Tannins were once believed to function as anti-herbivore defenses, but more and more ecologists now recognize them as important controllers of decomposition and nitrogen cycling processes. As concern grows about global warming, there is great interest to better understand the role of polyphenols as regulators of carbon cycling, particularly in northern boreal forests.

Polyphenols are also classified by the type and number of phenolic subcomponents present. More than one subcomponent can be present on a given polyphenol. Image File history File links This is a lossless scalable vector image. ... Chemical structure of gallic acid Gallic acid is an organic acid, also known as 3,4,5-trihydroxybenzoic acid, found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. ... Image File history File links This is a lossless scalable vector image. ... Flavonoids are a group of chemical compounds naturally found in certain fruits, vegetables, teas, wines, nuts, seeds, and roots. ... Image File history File links This is a lossless scalable vector image. ... Cinnamic acid has the formula C6H5CHCHCOOH and is an odorless white crystalline acid, which is slightly soluble in water. ... A bottle of tannic acid. ... Molecular structure of the flavone backbone (2-phenyl-1,4-benzopyrone) The term flavonoid refers to a class of plant secondary metabolites. ... A bottle of tannic acid. ... Lignin (sometimes lignen) is a chemical compound (complex, highly cross-linked aromatic polymer) that is most commonly derived from wood and is an integral part of the cell walls of plants, especially in tracheids, xylem fibres and sclereids. ...

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. Image File history File links This is a lossless scalable vector image. ... Image File history File links No higher resolution available. ... Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Image File history File links No higher resolution available. ... Phenol, also known under an older name of carbolic acid, is a colourless crystalline solid with a typical sweet tarry odor. ... Pyrocatechol, more commonly known as catechol, is a benzenediol, with the formula C6H4(OH)2. ... Pyrogallol or benzene-1,2,3-triol is a white crystalline powder and a powerful reducing agent. ... Resorcin (or resorcinol) is the (1,3) isomer of dihydroxybenzene (dihydric phenol). ... Phloroglucinol or benzene-1,3,5-triol is a process chemical widely used in the industrial synthesis of pharmaceuticals and high-energy chemicals (explosives). ... Hydroquinone, also benzene-1,4-diol, is an aromatic organic compound which is a type of phenol, having the chemical formula C6H4(OH)2. ... Coumaric acids are organic compounds that are hydroxy derivatives of cinnamic acid. ... Kaempferol is a natural flavonoid which has been isolated from Delphinium, Witch-hazel, grapefruit, and other plant sources. ... Epicatechin (EC) Epigallocatechin (EGC) Catechins are polyphenolic antioxidant plant metabolites, specifically flavonoids called flavan-3-ols. ... Quercetin is a flavonoid that forms the backbone for many other flavonoids, including the citrus flavonoids rutin, hesperidin, naringin and tangeritin. ... Caffeic acid, C9H8O4 is a naturally occurring phenolic compound, (formerly called a carbolic acid), which is found in many fruits, vegetables, and herbs, including coffee, although varying in amounts depending on the plant. ... Furelic acid protects our cells form ultraviolet rays. ... Hydroxytyrosol is a phytochemical. ... Epigallocatechin gallate (EGCG) is a type of catechin and is the most abundant catechin in tea. ... Tannins are astringent, bitter-tasting plant polyphenols that bind and precipitate proteins. ... Myricetin is a naturally-occurring flavonoid found in many grapes, berries, fruits, vegetables, herbs, as well as other plants. ... Sinapyl alcohol Sinapyl alcohol, also called sinapoyl alcohol or 4-(3-hydroxy-1-propenyl)-2,6-dimethoxy-phenol, is a phytochemical, one of the monolignols. ... The cis-isomer of resveratrol Resveratrol is a phytoalexin produced naturally by several plants when under attack by bacteria or fungi. ... Molecular structure of the flavone backbone (2-phenyl-1,4-benzopyrone) The term flavonoid refers to a class of plant secondary metabolites. ... Arbutin is a glycosylated benzoquinone extracted from the bearberry plant genus Arctostaphylos. ... Esterification is the general name for a chemical reaction in which two chemicals (typically an alcohol and an acid) form an ester as the reaction product. ... Methylation is a term used in the chemical sciences to denote the attachment or substitution of a methyl group on various substrates. ... Ellagic acid C14 H6 O8 CAS No. ... Epicatechin (EC) Epigallocatechin (EGC) Catechins are polyphenolic antioxidant plant metabolites, specifically flavonoids called flavan-3-ols. ... Theaflavin and its derivatives, known collectively as theaflavins, are polyphenols that are formed from catechins such as in tea leaves during the enzymatic oxidation (called fermentation by the tea trade) of tea leaves, such as in black tea. ... Thearubigins are polymeric polyphenols that are formed during the enzymatic oxidation (called fermentation by the tea trade) of tea leaves. ...

In Foods

Notable sources of polyphenols include berries, tea, beer, grapes/wine, olive oil, chocolate/cocoa, walnuts, peanuts, pomegranates, yerba mate, and other fruits and vegetables. This article is about the fruit. ... For other uses, see Tea (disambiguation). ... For other uses, see Beer (disambiguation). ... Species Vitis acerifolia Vitis aestivalis Vitis amurensis Vitis arizonica Vitis x bourquina Vitis californica Vitis x champinii Vitis cinerea Vitis x doaniana Vitis girdiana Vitis labrusca Vitis x labruscana Vitis monticola Vitis mustangensis Vitis x novae-angliae Vitis palmata Vitis riparia Vitis rotundifolia Vitis rupestris Vitis shuttleworthii Vitis tiliifolia Vitis... For other uses, see Wine (disambiguation). ... For the Popeye character, see Olive Oyl. ... For other uses, see Chocolate (disambiguation). ... For other uses, see Cocoa (disambiguation). ... This article is about the walnut tree. ... This article is about the legume. ... Species L. Balf. ... Binomial name A. St. ... For other uses, see Fruit (disambiguation). ... For other uses, see Vegetable (disambiguation). ...

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

Health benefits

Main article: Polyphenol antioxidant

Polyphenols were once briefly known as Vitamin P. However they were quickly found out to be non-essential and reclassified. The health benefits of specific polyphenols such as quercetin are well-established, there are less well-established claims of health benefits from all types of polyphenols. Molecular structure of flavone, a common Polyphenol antioxidant Polyphenol antioxidant is a class of multi-phenolic compounds known for their role of down-regulating free radical formation in mammals . ... Quercetin is a flavonoid that forms the backbone for many other flavonoids, including the citrus flavonoids rutin, hesperidin, naringin and tangeritin. ...

Research indicates that polyphenols may have antioxidant characteristics with potential health benefits. They may reduce the risk of cardiovascular disease and cancer. ^[3] Polyphenols have also been investigated as a source of additional health benefit in organic produce, but no conclusion was made. ^[4] Polyphenols bind with nonheme iron (e.g. from plant sources) in vitro in model systems. ^[5] This may decrease its absorption by the body. Space-filling model of the antioxidant metabolite glutathione. ...

See also

• List of phytochemicals and foods in which they are prominent
• Tannin
• Catechin
• Benzenediol

The following is a list of phytochemicals present in commonly consumed foods. ... A bottle of tannic acid. ... Epicatechin (EC) Epigallocatechin (EGC) Catechins are polyphenolic antioxidant plant metabolites, specifically flavonoids called flavan-3-ols. ... Benzenediols or dihydroxybenzenes are aromatic chemical compounds in which two hydroxyl groups are substituted onto a benzene ring. ...

References

1. ^ P. M. Dewick, The Biosynthesis of Shikimate Metabolites, Natural Product Reports 12:579-607 (1995)
2. ^ Clinical Guide to Nutrition and Dietary Supplements in Disease Management, by Jennifer R. Jamison, ISBN 0-443-07193-4, page 525.
3. ^ Arts, I.C. and P.C. Hollman, "Polyphenols and disease risk in epidemiologic studies." American Journal Clinical Nutrition, 2005. 81(1 Suppl): p. 317S-325S.
4. ^ Nutrition Perspectives Vol 30, No. 3 May/June 2005
5. ^ E. Matuschek, U. Svanberg (2002) "Oxidation of Polyphenols and the Effect on In vitro Iron Accessibility in a Model Food System", Journal of Food Science 67 (1), pp. 420–424.

External links

• Wine polyphenols vary with age and variety