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Encyclopedia > Tannin
A bottle of tannic acid.

Tannins are astringent, bitter-tasting plant polyphenols that bind and precipitate proteins. The term tannin refers to the use of tannins in tanning animal hides into leather; however, the term is widely applied to any large polyphenolic compound containing sufficient hydroxyls and other suitable groups (such as carboxyls) to form strong complexes with proteins and other macromolecules. Tannins have molecular weights ranging from 500 to over 3,000.[1] Image File history File linksMetadata Download high resolution version (1944x2592, 875 KB) I, the creator of this work, hereby release it into the public domain. ... Image File history File linksMetadata Download high resolution version (1944x2592, 875 KB) I, the creator of this work, hereby release it into the public domain. ... i suck A bottle of tannic acid, an astringent Astringent medicines cause shrinkage of mucous membranes or exposed tissues and are often used internally to check discharge of blood serum or mucous secretions. ... Polyphenols are a group of chemical substances found in plants, characterized by the presence of more than one phenol group per molecule. ... A representation of the 3D structure of myoglobin, showing coloured alpha helices. ... This article is about making hides into leather. ... Hides are skins obtained from animals that are used for human use. ... Modern leather-working tools Leather is a material created through the tanning of hides and skins of animals, primarily cattlehide. ... // Hydroxyl group The term hydroxyl group is used to describe the functional group -OH when it is a substituent in an organic compound. ... A carboxyl or carboxylic group is a functional group consisting of a carbon atom and an oxygen atom doubly bonded to each other. ... A macromolecule is a large molecule with a large molecular mass bonded covalently, but generally the use of the term is restricted to polymers and molecules which structurally include polymers. ... The molecular mass of a substance (less accurately called molecular weight and abbreviated as MW) is the mass of one molecule of that substance, relative to the unified atomic mass unit u (equal to 1/12 the mass of one atom of carbon-12). ...

Base Unit:
Gallic Acid

Flavone
Class/Polymer: Hydrolyzable Tannins Condensed Tannins

Tannins are usually divided into hydrolyzable tannins and condensed tannins (proanthocyanidins). 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. ... Hydrolysis is a chemical reaction or process in which a chemical compound reacts with water. ... Proanthocyanidin (also known as OPC, pycno-genol, leukocyanidin and leucoanthocyanin) is a a class of bioflavonoids. ...

Contents

Hydrolyzable Tannins

At the center of a hydrolyzable tannin molecule, there is a polyol carbohydrate (usually D-glucose). The hydroxyl groups of the carbohydrate are partially or totally esterified with phenolic groups such as gallic acid (in gallotannins) or ellagic acid (in ellagitannins). Hydrolyzable tannins are hydrolyzed by weak acids or weak bases to produce carbohydrate and phenolic acids. 3D (left and center) and 2D (right) representations of the terpenoid molecule atisane. ... A space-filling model of glucose Glucose, a simple monosaccharide sugar, is one of the most important carbohydrates and is used as a source of energy in animals and plants. ... 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. ... 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. ... Ellagic acid C14 H6 O8 CAS No. ...


Examples of gallotannins are the gallic acid esters of glucose in tannic acid (C76H52O46), found in the leaves and bark of many plant species. 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. ... A carboxylic acid ester. ... Glucose (Glc), a monosaccharide (or simple sugar), is an important carbohydrate in biology. ... This is a bottle of tannic acid. ... Leaves are an Icelandic five-piece alternative rock band who came to prominence in 2002 with their debut album, Breathe, drawing comparisons to groups such as Coldplay and Doves. ... For other meanings of bark, see Bark (disambiguation). ... For other uses, see Plant (disambiguation). ...


Condensed Tannins

Condensed tannins, also known as proanthocyanidins, are polymers of 2 to 50 (or more) flavonoid units that are joined by carbon-carbon bonds, which are not susceptible to being cleaved by hydrolysis. While hydrolyzable tannins and most condensed tannins are water soluble, some very large condensed tannins are insoluble. Proanthocyanidin (also known as oligomeric proanthocyanidin (OPC), pycnogenol, leukocyanidin and leucoanthocyanin) is a class of flavonoids. ... Molecular structure of flavone The term flavonoid refers to a class of plant secondary metabolites based around a phenylbenzopyrone structure. ... Hydrolysis is a chemical reaction or process in which a chemical compound reacts with water. ...


Foods with tannins

Tea

Darjeeling tea infusion
Darjeeling tea infusion

The tea plant (Camellia sinensis) is an example of a plant said to have a naturally high tannin content. When any type of tea leaf is steeped in hot water it brews a "tart" (astringent) flavor that is characteristic of tannins. This is due to the catechins and other flavonoids. Tea "tannins" are chemically distinct from other types of plant tannins such as tannic acid[2] and tea extracts have been reported to contain no tannin[3]. Image File history File links Size of this preview: 800 × 543 pixelsFull resolution (2650 × 1800 pixel, file size: 914 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Tea Darjeeling tea ... Image File history File links Size of this preview: 800 × 543 pixelsFull resolution (2650 × 1800 pixel, file size: 914 KB, MIME type: image/jpeg) File links The following pages on the English Wikipedia link to this file (pages on other projects are not listed): Tea Darjeeling tea ... Tea leaves in a Chinese gaiwan. ... Epicatechin (EC) Epigallocatechin (EGC) Catechins are polyphenolic antioxidant plant metabolites, specifically flavonoids called flavan-3-ols. ... Molecular structure of flavone The term flavonoid refers to a class of plant secondary metabolites based around a phenylbenzopyrone structure. ...


Wine

A glass of red wine
A glass of red wine

Tannins (mainly condensed tannins) are also found in wine, particularly red wine. Tannins in wine can come from many sources and the tactile properties differ depending on the source. Tannins in grape skins and seeds (the latter being especially harsh) tend to be more noticeable in red wines, which are fermented while in contact with the skins and seeds. Tannins extracted from grapes are condensed tannins, which are polymers of procyanidin monomers. Hydrolysable tannins are extracted from the oak wood the wine is aged in. Hydrolysable tannins are more easily oxidised than condensed tannins. Download high resolution version (428x800, 53 KB) Red wine. ... Download high resolution version (428x800, 53 KB) Red wine. ... For other uses, see Wine (disambiguation). ... It has been suggested that Veraison be merged into this article or section. ... A ripe red jalapeño cut open to show the seeds For other uses, see Seed (disambiguation). ... For other uses, see Fermentation. ... Proanthocyanidin (also known as oligomeric proanthocyanidin (OPC), pycnogenol, leukocyanidin and leucoanthocyanin) is a class of flavonoids. ... In chemistry, a monomer (from Greek mono one and meros part) is a small molecule that may become chemically bonded to other monomers to form a polymer. ...


Modern winemakers take great care to minimize undesirable tannins from seeds by crushing grapes gently to extract their juice. Pressing the grapes results in press wine which is more tannic and might be kept separately. Wines can also take on tannins if matured in oak or wood casks with a high tannin content. Tannins play an important role in preventing oxidation in aging wine and appear to polymerize and make up a major portion of the sediment in wine. The term vintner is applied to wine merchants as well as winemakers. ... A barrel is a hollow cylindrical container, usually made of wood staves and bound with iron bands. ... The most fundamental reactions in chemistry are the redox processes. ... A polymer (from Greek: πολυ, polu, many; and μέρος, meros, part) is a substance composed of molecules with large molecular mass composed of repeating structural units, or monomers, connected by covalent chemical bonds. ...


Recently, a study in wine production and consumption has shown that tannins in the form of procyanidins, have a beneficial effect on vascular health. The study showed that tannins suppressed production of the peptide responsible for hardening arteries. To support their findings, the study also points out that wines from the regions of southwest France and Sardinia are particularly rich in procyanidins, and that these regions also produce populations with longer life spans.[4] Proanthocyanidin (also known as oligomeric proanthocyanidin (OPC), pycnogenol, leukocyanidin and leucoanthocyanin) is a class of flavonoids. ...


Fruits

Pomegranates

Pomegranate fruit, opened
Pomegranate fruit, opened
Pomegranate seeds

Pomegranates contain a diverse array of tannins, particularly hydrolysable tannins. The most abundant of pomegranate tannins are called punicalagins. Punicalagins have a molecular weight of 1038 and are the largest molecule found intact in rat plasma after oral ingestion[5] and were found to show no toxic effects in rats who were given a 6% diet of punicalagins for 37 days.[6]. Punicalagins are also found to be the major component responsible for pomegranate juice's antioxidant and health benefits [7] Image:Pomegranate03 edit. ... Image:Pomegranate03 edit. ... Image File history File links Download high resolution version (823x805, 87 KB) Summary Pomegranate Seeds Licensing Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Image File history File links Download high resolution version (823x805, 87 KB) Summary Pomegranate Seeds Licensing Permission is granted to copy, distribute and/or modify this document under the terms of the GNU Free Documentation License, Version 1. ... Binomial name L. For the color see: Pomegranate (color) The Pomegranate (Punica granatum) is a fruit-bearing deciduous shrub or small tree growing to 5–8 m tall. ... Punicalagins are tannins, large polyphenol compound which are isomers of 2,3-(S)-hexahydroxydiphenoyl-4,6-(S,S)-gallagyl-D-glucose, hydrolysable tannins with a molecular weight of 1038. ... Space-filling model of the antioxidant metabolite glutathione. ...


Several dietary supplements and nutritional ingredients are available that contain extracts of whole pomegranate and/or are standardized to punicalagins, the marker compound of pomegranate. Extracts of pomegranate are also Generally Recognized as Safe (GRAS) by the United States Food and Drug Administration. It has been recommended to look for pomegranate ingredients that mimic the polyphenol ratio of the fruit, as potent synergistic effects have been observed in 'natural spectrum' extracts, especially pomegranate concentrate normalized to punicalagins.[8] Generally Recognized as Safe (GRAS) is an FDA designation that a chemical or substance (including certain pesticides) added to food is considered safe by experts, and so is exempted from the usual FFDCA food additive tolerance requirements. ... hi “FDA” redirects here. ...


Persimmons

Some persimmons are highly astringent and therefore inedible when they are not extremely ripe (specifically the Korean, American, and Hachiya or Japanese). This is due to the high level of tannins, and if eaten by humans (and many other animals), the mouth will become completely dry, yet the saliva glands will continue to secrete saliva which cannot affect the tannin-laced food. Areca Catechu also contains tannin which contributes to its antibacterial properties Species See text A Persimmon is any of a number of species of trees of the genus Diospyros, and the edible fruit borne by them. ...


Berries

Strawberries in a bowl
Strawberries in a bowl

Most berries, such as cranberries[9] strawberries and blueberries,[10] contain both hydrolyzable and condensed tannins. Image File history File links Metadata Size of this preview: 799 × 599 pixelsFull resolution (1841 × 1381 pixel, file size: 830 KB, MIME type: image/jpeg) Photographer: Alisdair McDiarmid from Glasgow, United Kingdom Title: Strawberries Description: Late season, slightly over-ripe strawberries. ... Image File history File links Metadata Size of this preview: 799 × 599 pixelsFull resolution (1841 × 1381 pixel, file size: 830 KB, MIME type: image/jpeg) Photographer: Alisdair McDiarmid from Glasgow, United Kingdom Title: Strawberries Description: Late season, slightly over-ripe strawberries. ... Species Vaccinium erythrocarpum Vaccinium macrocarpon Vaccinium microcarpum Vaccinium oxycoccus Approximate ranges of the cranberries in sect. ... Strawberries Promo Strawberries is an album by The Damned released October 1982 on Bronze Records (catalogue #BRON 542). ... For other uses, see Blueberry (disambiguation). ...


Nutrition

If ingested in excessive quantities, tannins inhibit the absorption of minerals such as iron into the body. This is because tannins are metal ion chelators, and tannin-chelated metal ions are not bioavailable. This may not be bad for someone with an infection, as iron is mopped up by the immune system to keep microorganisms from properly multiplying. Tannins have been shown to precipitate proteins,[1] which inhibits in some ruminant animals the absorption of nutrients from high-tannin grains such as sorghum. A mineral is a naturally occurring substance formed through geological processes that has a characteristic chemical composition, a highly ordered atomic structure and specific physical properties. ... For other uses, see Iron (disambiguation). ... Chelation (from Greek χηλή, chelè, meaning claw) is the process of reversible binding (complexation) of a ligand - the chelant, chelator, chelating agent, sequestering agent, or complexing agent - to a metal ion, forming a metal complex, the chelate. ... In pharmacology, bioavailability is used to describe the fraction of an administered dose of unchanged drug that reaches the systemic circulation, one of the principal pharmacokinetic properties of drugs. ... It has been suggested that this article or section be merged with Ruminantia. ... Species About 30 species, see text Sorghum is a genus of numerous species of grasses, some of which are raised for grain and many of which are utilised as fodder plants either cultivated or as part of pasture. ...


Uses

Tannins are an important ingredient in the process of tanning leather. Oak bark has traditionally been the primary source of tannery tannin, though inorganic tanning agents are also in use today. Species See List of Quercus species The term oak can be used as part of the common name of any of several hundred species of trees and shrubs in the genus Quercus (from Latin oak tree), and some related genera, notably Cyclobalanopsis and Lithocarpus. ... This article is about making hides into leather. ...


Tannins may be employed medicinally in antidiarrheal, hemostatic, and antihemorrhoidal compounds. An antidiarrhoeal drug is any medication which provides symptomatic relief for diarrhoea. ... Hemostasis refers to a process whereby bleeding is halted in most animals with a closed circulatory system. ... Hemorrhoids (also known as haemorrhoids, emerods, or piles) are varicosities or swelling and inflammation of veins in the rectum and anus. ...


Tannins produce different colors with ferric chloride (either blue, blue black, or green to greenish black) according to the type of tannin. Iron gall ink is produced by treating a solution of tannins with iron(II) sulfate. Ferric chloride (FeCl3) is an iron-based salt. ... Oak galls and iron(II) sulfate, ingredients of iron gall ink Iron gall ink (sometimes iron gall nut ink) is a purple-black ink made from iron salts and tannin from vegetable sources. ... Iron(II) sulfate is the chemical compound with the formula (FeSO4). ...


Tannin is a component in a type of industrial particleboard adhesive developed jointly by the Tanzania Industrial Research and Development Organization and Forintek Labs Canada. Particle board is a material manufactured from wood particles (e. ... “Glue” redirects here. ...


Potential Medical

Tannins, including gallo and ellagic acid (epigallitannins), are inhibitors of HIV replication. Ellagic acid C14 H6 O8 CAS No. ...

  • 1,3,4-Tri-O-galloylquinic acid
  • 3,5-di-O-galloyl-shikimic acid,
  • 3,4,5-tri-O-galloylshikimic acid
  • punicalin
  • punicalagin

inhibited HIV replication in infected H9 lymphocytes with little cytotoxicity. Two compounds, punicalin and punicacortein C, inhibited purified HIV reverse transcriptase.[11] Punicalagins are dimeric hydrolysable tannins that are found in abundance in pomegranate (Punica granatum). ... A lymphocyte is a type of white blood cell involved in the human bodys immune system. ... In biochemistry, a reverse transcriptase, also known as RNA-dependent DNA polymerase, is a DNA polymerase enzyme that transcribes single-stranded RNA into double-stranded DNA. Normal transcription involves the synthesis of RNA from DNA, hence reverse transcription is the reverse of this. ...


References

Notes

  1. ^ a b Bate-Smith and Swain, 1962, Flavonoid compounds. In : Comparative biochemistry. Florkin M. Mason H.S. Eds. Vol III. 75-809. Academic Press, New-York.
  2. ^ Hamilton-Miller JM. Antimicrobial properties of tea (Camellia sinensis L.). Antimicrob Agents Chemother. 39(11): 2375-2377 (1995) PMID 8585711
  3. ^ Wheeler, S.R. Tea and Tannins Science 204: 6-8 (1979) [1] as cited in Yam TS, Hamilton-Miller JM, Shah S. The effect of a component of tea (Camellia sinensis) on methicillin resistance, PBP2' synthesis, and beta-lactamase production in Staphylococcus aureus. J Antimicrob Chemother. 42(2):211-216. (1998) PMID 9738838
  4. ^ R. Corder, W. Mullen, N. Q. Khan, S. C. Marks, E. G. Wood, M. J. Carrier and A. Crozier Nature 444, 566 (30 November 2006)
  5. ^ Biomed. Pharmacother. 2002, 56, 276-82
  6. ^ J. Agric. Food Chem. 2003, 51, 3493-3501
  7. ^ J Agric Food Chem 2000 48 (10) 4581-89
  8. ^ J Nutr Biochemistry 2005 (16) 360-367
  9. ^ Vattem, D. A. Ghaedian, R. Shetty, K. Enhancing health benefits of berries through phenolic antioxidant enrichment: focus on cranberry Asia Pacific Journal of Clinical Nutrition (2005) 14(2) 120-130 [2]
  10. ^ R. Puupponen-Pimiä, L. Nohynek, C. Meier, M. Kähkönen, M. Heinonen, A. Hopia & K.-M. Oksman-Caldentey, Antimicrobial properties of phenolic compounds from berries, Journal of Applied Microbiology 90(4) pp494 (2001) [3]
  11. ^ [4]

General References

  • L. Calvi, G.C.J. Mwalongo, B.A. Mwingira, B. Riedl and J.A. Shields; Characterization of Wattle-Tannin-Based Adhesives for Tanzania (A paper published in Holzforchung Vol 49 No 2, 1995).

External links

  • Tannin and wine making!
  • Tannins: fascinating but sometimes dangerous molecules
  • Tannin ChemistryPDF (1.41 MiB)

  Results from FactBites:
 
Bark Tanning: Tannins and Tannin Sources (1084 words)
Tannins occur in nearly every plant from all over the world, in all climates.
Tannin is usually concentrated in the inner bark (cambium layer).
Tannin is water soluble and will be leached out of wood or bark that has been left out in the rain.
  More results at FactBites »

 
 

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