Page 120 - phytochemistry II -pharmD general

Metabolomic fate and bioavailability of ellagitannins
✓ Many studies have proven that ETs are not bioavailable as such, and they

have never been detected in human plasma after normal consumption of
ET-rich foods
✓ Ellagitannins are probably not bioavailable because:

➢ their size (high molecular weight)
➢ Their relatively high polarity and
➢ the presence of a C▬C linkage
➢ Additionally, during ingestion, ETs can also bind some proteins

in saliva and cause astringency, and in this case, they may not
be metabolized further
➢ most ETs sensitive to acidic and basic hydrolysis in the
stomach and the duodenum, respectively, they release free
ellagic acid, which is at its turn poorly bioavailable.
✓ Low bioavailability of EA is probably due to low water solubility, and to its
ability to bind irreversibly to cellular DNA and proteins, or to form poorly
soluble complexes with calcium and magnesium ions which affects
transcellular absorption

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