Hydrolyzable tannins constitute a class of plant bioactive polyphenols primarily composed
of ellagitannins and gallotannins derived from the metabolism of gallic acid. Ellagitannins
feature galloyl units esterified to a sugar core, usually glucose, and characterized
by the presence of biaryl and diaryl ether bonds between some or all of their galloyl
units.[1] Among ellagitannins, there exists a subclass of structurally unique nonahydroxyterphenoyl
(NHTP)-bearing C -glucosidic molecules featuring an open-chain glucose core and exemplified by vescalagin.
The fact that some of these C -glucosidic ellagitannins are found in wine as a result of aging of this beverage
in oak-made barrels provided us with the impetus to examine their chemical reactivity
and biological activity. Indeed, during aging in oak barrels, the hydroalcoholic and
slightly acidic (i.e. , pH 3–4) wine solution enables the solid-liquid extraction of these ellagitannins.
Once in the wine solution, some of these natural products such as vescalagin can capture
grape-derived nucleophilic entities such as the flavanols catechin and epicatechin
and the anthocyanin oenin to furnish condensation products, some of them having been
postulated as active principles in Asian herbal medicines.[2] Of pharmacological importance is the fact that several of these found-in-wine ellagitannin
hybrids are much more potent than etoposide (VP-16) at inhibiting in vitro the anti-cancer target DNA topoisomerase IIa.[2a,b] Furthermore, we recently discovered that vescalagin is capable of drastically perturbing
the actin cytoskeleton by interacting selectively with the actin filaments, both in vitro and in cellulo .[3] Moreover, gallotannins, in which galloyl units and/or depsidically-linked chains of
galloyl units are usually esterified to a glucopyranose core, and some of their simpler
precursors exhibit some interesting properties with possible applications as antifibrillogenic
agents. Thus, the various biophysico-chemical properties we unveiled for these hydrolysable
tannins will be presented and their exploitation in the development of therapeutic
agents discussed during this lecture.
[1] Quideau, S. (Ed.) Chemistry and Biology of Ellagitannins, An Underestimated Class of Bioactive Plant
Polyphenols ; World Scientific Publishing: Singapore, 2009 .
[2] a) Quideau, S.; Jourdes, M.; Saucier, C.; Glories, Y.; Pardon, P.; Baudry, C.
Angew. Chem. Int. Ed.
2003 , 42 , 6012–6014 (
selected for the cover
); b) Quideau, S.; Jourdes, M.; Lefeuvre, D.; Montaudon, D.; Saucier, C.; Glories,
Y.; Pardon, P.; Pourquier, P. Chem. Eur. J.
2005 , 11 , 6503–6513 (
selected for the cover
); c) Chassaing, S.; Lefeuvre, D.; Jacquet, R.; Jourdes, M.; Ducasse, L.; Galland,
S.; Grelard, A.; Saucier, C.; Teissedre, P.-L.; Dangles, O.; Quideau, S. Eur. J. Org. Chem.
2010 , 55–63 (
selected for the cover
).
[3] Quideau, S.; Douat-Casassus, C.; Delannoy López, D. M.; Di Primo, C.; Chassaing,
S.; Jacquet, R.; Saltel, F.; Genot, E. Angew. Chem. Int. Ed.
2011 , 50 , 5099–5104.
