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. 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.[1]

Ellagitannins contain various numbers of hexahydroxydiphenoyl 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.[2]

Ellagitannins generally form macrocycles, whereas gallotannins do not.

Examples

Metabolism

Degradation

Urolithins, such as urolithin A, are microflora human metabolites of dietary ellagic acid derivatives.[3]

Natural occurrences

Ellagitannins are reported in dicotyledoneous angiospermes, and notably in species in the order Myrtales, such as the pomegranate.[4][5]

See also

References
  1. MALDI-TOF Mass Spectrometric Analysis of Hydrolysable Tannins
  2. 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
  3. Davis, CD; Milner, JA (Oct 2009). "Gastrointestinal microflora, food components and colon cancer prevention". J Nutr Biochem. 20 (10): 743–52. doi:10.1016/j.jnutbio.2009.06.001. PMC 2743755. PMID 19716282.
  4. Yoshida, Takashi (2010). "Structural Features and Biological Properties of Ellagitannins in Some Plant Families of the Order Myrtales". International Journal of Molecular Sciences. 11 (1): 79–106. doi:10.3390/ijms11010079. PMC 2820991. PMID 20162003.
  5. Gómez-Caravaca, A. M.; Verardo, V; Toselli, M; Segura-Carretero, A; Fernández-Gutiérrez, A; Caboni, M. F. (2013). "Determination of the major phenolic compounds in pomegranate juices by HPLC−DAD−ESI-MS". Journal of Agricultural and Food Chemistry. 61 (22): 5328–37. doi:10.1021/jf400684n. PMID 23656584.

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.
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