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

Castalagin
Castalin
Casuarictin
Grandinin
Oenothein B from Willowherbs (Epilobium spp.)
Roburin A
Tellimagrandin II
Terflavin B
Vescalagin
Pomegranate ellagitannins, many compounds
- Punicalagin
- Punicalin

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]

References

^ Landete, J.M. (2011). "Ellagitannins, ellagic acid and their derived metabolites: A review about source, metabolism, functions and health". Food Research International. 44 (5): 1150–1160. doi:10.1016/j.foodres.2011.04.027.
^ 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
^ 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.
^ 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.
^ 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. Bibcode:2013JAFC...61.5328G. doi:10.1021/jf400684n. PMID 23656584.