The ellagitannins are a diverse class of

hydrolyzable tannin A hydrolyzable tannin or pyrogallol-type tannin is a type of tannin that, on heating with hydrochloric or sulfuric acids, yields gallic or ellagic acids. At the center of a hydrolyzable tannin molecule, there is a carbohydrate (usually D-glucos ...

s, a type of

polyphenol Polyphenols () are a large family of naturally occurring organic compounds characterized by multiples of phenol units. They are abundant in plants and structurally diverse. Polyphenols include flavonoids, tannic acid, and ellagitannin, some o ...

formed primarily from the oxidative linkage of

galloyl Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6 H2( OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. It ...

groups in 1,2,3,4,6-pentagalloyl glucose. Ellagitannins differ from

gallotannin A gallotannin is any of a class of molecules belonging to the hydrolysable tannins. Gallotannins are polymers formed when gallic acid, a polyphenol monomer, esterifies and binds with the hydroxyl group of a polyol carbohydrate such as glucose. Meta ...

s, in that their

groups are linked through C-C bonds, whereas the galloyl groups in gallotannins are linked by depside bonds. Ellagitannins contain various numbers of

hexahydroxydiphenoyl Hexahydroxydiphenic acid is an organic compound with the formula HO)3C6HCO2Hsub>2. It is the oxidatively coupled derivative of gallic acid It is a white solid, although samples are typically brown owing to oxidation. left, 142px, Ellagic acid. ...

units, as well as

units and/or sanguisorboyl units bounded to sugar moiety. In order to determine the quantity of every individual unit, the hydrolysis of the extracts with

trifluoroacetic acid Trifluoroacetic acid (TFA) is an organofluorine compound with the chemical formula CF3CO2H. It is a structural analogue of acetic acid with all three of the acetyl group's hydrogen atoms replaced by fluorine atoms and is a colorless liquid with ...

in methanol/water system is performed. Hexahydroxydiphenic acid, created after hydrolysis, spontaneously lactonized to

ellagic acid Ellagic acid is a polyphenol found in numerous fruits and vegetables. It is the dilactone of hexahydroxydiphenic acid. Name The name comes from the French term ''acide ellagique'', from the word ''galle'' spelled backwards because it can be ...

, and sanguisorbic acid to sanguisorbic acid dilactone, while

gallic acid Gallic acid (also known as 3,4,5-trihydroxybenzoic acid) is a trihydroxybenzoic acid with the formula C6 H2( OH)3CO2H. It is classified as a phenolic acid. It is found in gallnuts, sumac, witch hazel, tea leaves, oak bark, and other plants. I ...

remains intact. Ellagitannins generally form

macrocycle Macrocycles are often described as molecules and ions containing a ring of twelve or more atoms. Classical examples include the crown ethers, calixarenes, porphyrins, and cyclodextrins. Macrocycles describe a large, mature area of chemistry. ...

s, whereas gallotannins do not.

Examples

Castalagin Castalagin is an ellagitannin, a type of hydrolyzable tannin, found in oak and chestnut wood and in the stem barks of '' Anogeissus leiocarpus'' and ''Terminalia avicennoides''. Castalagin is the diastereomer of vescalagin in C-1 of the glycosidi ...

* Castalin * Casuarictin *

Grandinin Grandinin is an ellagitannin. It can be found in ''Melaleuca quinquenervia'' leavesPolyphenols of Melaleuca quinquenervia leaves - pharmacological studies of grandinin. Moharram F. A., Marzouk M. S., El-Toumy S. A. A., Ahmed A. A. E. and Aboutabl ...

* Oenothein B from Willowherbs (Epilobium spp.) *

Roburin A Roburin A is a tannin found in oak wood (''Quercus robur'' and ''Quercus petraea'' or ''Quercus alba'') or oak cork (''Quercus suber''). It is a dimeric compound, composed of two vescalagin Castalagin is an ellagitannin, a type of hydrolyzable ta ...

Tellimagrandin II Tellimagrandin II is the first of the ellagitannins formed from 1,2,3,4,6-pentagalloyl-glucose. It can be found in '' Geum japonicum'' and ''Syzygium aromaticum'' (clove).Purification and Characterization of Eugeniin as an Anti-herpesvirus Compound ...

Terflavin B Terflavin B is an ellagitannin, a type of hydrolysable tannin. It can be found in ''Myrobalanus chebula'' (''Terminalia chebula''), the black chebulic, and in ''Terminalia catappa'', the Indian almond. It is formed from a nonahydroxytriphenic aci ...

Vescalagin Castalagin is an ellagitannin, a type of hydrolyzable tannin, found in oak and chestnut wood and in the stem barks of '' Anogeissus leiocarpus'' and ''Terminalia avicennoides''. Castalagin is the diastereomer of vescalagin in C-1 of the glycosidi ...

Pomegranate ellagitannin The pomegranate ellagitannins, which include punicalagin isomers, are ellagitannins found in the sarcotestas, rind (peel), bark or heartwood of pomegranates (''Punica granatum''). Chemistry As the chemistry of punicalagins became known it was f ...

s, many compounds **

Punicalagin Punicalagin is an ellagitannin, a type of phenolic compound. It is found as alpha and beta isomers in pomegranates (''Punica granatum''), ''Terminalia catappa'', ''Terminalia myriocarpa'', and in ''Combretum molle'', the velvet bushwillow, a plant ...

Punicalin Punicalin is an ellagitannin. It can be found in ''Punica granatum'' (pomegranate) or in the leaves of ''Terminalia catappa'', a plant used to treat dermatitis and hepatitis. It is also reported in '' Combretum glutinosum'', all three species bein ...

Metabolism

Degradation

Urolithin Urolithins are Microbiota, microflora metabolites of dietary ellagic acid derivatives, such as ellagitannins. They are produced in the Gastrointestinal tract, gut, and found in the urine in the form of urolithin B glucuronide after absorption of e ...

s, such as

urolithin A Urolithin A is a metabolite compound resulting from the transformation of ellagitannins by the gut bacteria. It belongs to the class of organic compounds known as benzo-coumarins or dibenzo-α- pyrones. Its precursors – ellagic acids and ...

, are microflora human metabolites of dietary

derivatives.

Natural occurrences

Ellagitannins are reported in dicotyledoneous angiospermes, and notably in species in the order Myrtales, such as the

pomegranate The pomegranate (''Punica granatum'') is a fruit-bearing deciduous shrub in the family Lythraceae, subfamily Punicoideae, that grows between tall. The pomegranate was originally described throughout the Mediterranean Basin, Mediterranean re ...

References

External links

Tannin Chemistry
(Tannin Handbook, Copyright 1998, 2002, 2011, Ann E. Hagerman) {{Ellagitannin Aromatase inhibitors