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
1,2,3,4,6-Pentagalloylglucose is the pentagallic acid ester of glucose. It is a gallotannin and the precursor of ellagitannins.
Pentagalloyl glucose can precipitate proteins, including human salivary α-amylase.
Natural occurrence
1,2,3,4,6-Pe ...
. 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
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 are linked through C-C bonds, whereas the galloyl groups in gallotannins are linked by
depside
A depside is a type of polyphenolic compound composed of two or more monocyclic aromatic units linked by an ester bond. Depsides are most often found in lichens, but have also been isolated from higher plants, including species of the Ericaceae, L ...
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
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 ...
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
Sanguisorbic acid is a constituent of some ellagitannins. It is constituted by a hexahydroxydiphenic acid unit linked by an O-C bond to a gallic acid. The differences with its isomers, valoneic acid and nonahydroxytriphenic acid, are that the hydr ...
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
Casuarictin is an ellagitannin, a type of hydrolysable tannin. It can be found in ''Casuarina'' and ''Stachyurus'' species.Tannins of Casuarina and Stachyurus species. I: Structures of pendunculagin, casuarictin, strictinin, casuarinin, casuariin, ...
*
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
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 ...
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 ...
.
See also
*
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 ...
-
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 ...
*
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 ...
s
*
List of antioxidants in food
This is a list of antioxidants naturally occurring in food. Vitamin C and vitamin E – which are ubiquitous among raw plant foods – are confirmed as dietary antioxidants, whereas vitamin A becomes an antioxidant following metabolism of p ...
References
Further reading
* Quideau, Stéphane (editor). ''Chemistry and Biology of Ellagitannins: An Underestimated Class of Bioactive Plant Polyphenols'', 2009, World Scientific Publishing.
Table of Contents Preface Chapter 1
External links
Tannin Chemistry(Tannin Handbook, Copyright 1998, 2002, 2011, Ann E. Hagerman)
{{Ellagitannin
Aromatase inhibitors