Ellagitannin

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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.


Examples[edit]

Metabolism[edit]

Biosynthesis[edit]

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[edit]

Urolithins, such as urolithin A, are microflora human metabolites of dietary ellagic acid derivatives.[5]

Natural occurrences[edit]

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[edit]

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[edit]

References[edit]

  1. ^ Sepulveda, Leonardo; Alberto Ascacio; Raul Rodriguez-Herrera; Antonio Aguilera-Carbo; Cristobal N. Aguilar (30 May 2011). "Ellagic acid: Biological properties and biotechnological development for production processes". African Journal of Biotechnology 10 (22): 4518–4523. Retrieved 12 November 2011. 
  2. ^ MALDI-TOF Mass Spectrometric Analysis of Hydrolysable Tannins
  3. ^ 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. ^ a b c Ascacio-Valdés JA et al. (2011) Review: Ellagitannins: Biosynthesis, biodegradation and biological properties Journal of Medicinal Plants Research Vol. 5(19):4696-4703
  5. ^ 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
  6. ^ 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[edit]

  • 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[edit]

  • Tannin Chemistry (Tannin Handbook, Copyright 1998, 2002, 2011, Ann E. Hagerman)