Ellagitannin
The ellagitannins are a diverse class of hydrolyzable tannins, a type of polyphenol formed primarily from the oxidative linkage of galloyl groups in 1,2,3,4,6-pentagalloyl glucose.[1] Ellagitannins differ from gallotannins, in that their galloyl groups are linked through C-C bonds, whereas the galloyl groups in gallotannins are linked by depside bonds.[2]
Ellagitannins contain various numbers of hexahydroxydiphenoyl (HHDP) units, as well as galloyl 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 in methanol/water system is performed. Hexahydroxydiphenic acid, created after hydrolysis, spontaneously lactonized to ellagic acid, and sanguisorbic acid to sanguisorbic acid dilactone, while gallic acid remains intact.[3]
Ellagitannins generally form macrocycles, whereas gallotannins don't.
Contents
Examples
- Castalagin
- Castalin
- Casuarictin
- Grandinin
- Punicalagin
- Punicalin
- Roburin A
- Tellimagrandin II
- Terflavin B
- Vescalagin
Metabolism
Biosynthesis
According to a 2011 review, "Information about ETs {ellagitannin} biosynthesis is limited and confused, however, it is known that the biosynthesis begins when a glucose molecule forms a complex with a gallic acid (GA) molecule."[4] (see : Glucogallin) Tellimagrandin II, one of the first ellagitannins, forms from pentagalloyl glucose by oxydative dehydrogenation and coupling of 2 galloyl groups.
Degradation
Urolithins, such as urolithin A, are microflora human metabolites of dietary ellagic acid derivatives.[5]
Natural occurrences
Ellagitannins are reported in dicotyledoneous angiospermes, and notably in species in the order Myrtales.[6]
Ellagitannins and ellagic acid have been found as natural components in 46 different foods, with the red raspberry (Rubus idaeus) identified as a major source.[4]
Research into potential medicinal uses
Ellagitannins have been investigated in cells and animals in laboratories for antioxidant, anti-cancer, antiviral, antimicrobial, and anti-parastite activities, as well as their ability to regulate blood glucose.[4]
See also
References
- ↑ Lua error in package.lua at line 80: module 'strict' not found.
- ↑ MALDI-TOF Mass Spectrometric Analysis of Hydrolysable Tannins
- ↑ Structural diversity and antimicrobial activities of ellagitannins. T. Yoshida, Ts. Hatano, H. Ito, T. Okuda, S. Quideau (Ed.), Chemistry and Biology of Ellagitannins, World Scientific Publishing, Singapore (2009), pages 55–93
- ↑ 4.0 4.1 4.2 Ascacio-Valdés JA et al. (2011) Review: Ellagitannins: Biosynthesis, biodegradation and biological properties Journal of Medicinal Plants Research Vol. 5(19):4696-4703
- ↑ Davis CD, Milner JA. Gastrointestinal microflora, food components and colon cancer prevention. J Nutr Biochem. 2009 Oct;20(10):743-52. doi: 10.1016/j.jnutbio.2009.06.001. PMID 19716282
- ↑ Structural Features and Biological Properties of Ellagitannins in Some Plant Families of the Order Myrtales. Takashi Yoshida *, Yoshiaki Amakura and Morio Yoshimura, Int. J. Mol. Sci., 2010, 11, pages 79-106, doi:10.3390/ijms11010079
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)
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