Ellagitannin is a hydrolysable polymer contrary to the rest of the family of tannins and can be hydrolyzed to more simple monomers that can be eventually metabolized and that can become bioavailable with subsequent exposition of the body to these metabolites.
Ellagitannins along with condensed tannins, comprise one of the two large groups of tannins, and have the hexahydroxydiphenoyl (HHDP) group, or a similar group derivable from the HHDP group, in their molecules. The HHDP group is biosynthetically formed through intramolecular, oxidative C-C bond formation between neighboring galloyl groups in galloylglucoses.
Condensed tannins are formed through the condensation of flavan-3-ols (catechins) and are often referred to as proanthocyanidins.
The ellagitannins include:
(1) monomeric ellagitannins,
(2) C-glycosidic ellagitannins with an open-chain glucose core,
(3) condensates of C-glycosidic tannins with flavan-3-ol (complex tannin), and
(4) oligomers which are produced through intermolecular C-O or C-C bonds between monomers
Ellagitannins form a diverse group of bioactive polyphenols with anti-inflammatory, anticancer, antioxidant and antimicrobial (antibacterial, antifungal and antiviral) activity.
The consumption of ellagitannins has often been associated with positive effects on many pathologies, including cardiovascular diseases, neurodegenerative syndromes, and cancer. Although multiple biological activities (antioxidant, anti-inflammatory, chemo preventive) have been known for ellagitannins, their limited bioavailability prevents reaching significant concentrations in systemic circulation.
There may be monomeric (nupharin A, geraniin, tellimagrandin II), oligomeric (nupharin E, nupharin C, hirtellin A), or C-glycosidic (vescalagin, castalagin). Ellagitannins tend to form high molecular weight dimers and oligomers.
Properties of ellagitannins
