page_title: Flavan-3-ol
section_title: Metabolism in humans
hierarchical_section_title: Flavan-3-ol / Metabolism of flavan-3-ols / Metabolism in humans
caption_attribution_description: English: SREM: structurally related (−)-epicatechin metabolites. 5C-RFM: 5-carbon ring fission metabolites. 3/1C-RFM: 3- and 1-carbon-side chain ring fission metabolites. The structures of the most abundant (−)-epicatechin metabolites present in the systemic circulation and in urine are depicted.
context_page_description: Flavan-3-ols are derivatives of flavans that possess a 2-phenyl-3,4-dihydro-2H-chromen-3-ol skeleton. These compounds include catechin, epicatechin gallate, epigallocatechin, epigallocatechin gallate, proanthocyanidins, theaflavins, thearubigins.
  Flavanols are not to be confused with flavonols, a class of flavonoids containing a ketone group.
  The single-molecule catechin, or isomer epicatechin, adds four hydroxyls to flavan-3-ol, making building blocks for concatenated polymers and higher order polymers.
  Flavanols possess two chiral carbons, meaning four diastereoisomers occur for each of them.
  Catechins are distinguished from the yellow, ketone-containing flavonoids such as quercitin and rutin, which are called flavonols. Early use of the term bioflavonoid was imprecisely applied to include the flavanols, which are distinguished by absence of ketone. Catechin monomers, dimers, and trimers are colorless. Higher order polymers, anthocyanidins, exhibit deepening reds and become tannins.
context_section_description: Most data for human metabolism of flavan-3-ols are available for monomeric compounds, especially Catechin. These compounds are taken up and metabolised upon uptake in the jejunum, mainly by O-methylation and glucuronidation, and then further metabolised by the liver. The colonic microbiome has also an important role in the metabolism of flavan-3-ols and they are catabolised to smaller compounds such as 5-(3′/4′-dihydroxyphenyl)-γ-valerolactones and hippuric acid. Only flavan-3-ols with an intact (epi)catechin moiety can be metabolised 5-(3′/4′-dihydroxyphenyl)-γ-valerolactones.
caption: Schematic representation of the flavan-3-ol (−)-epicatechin metabolism in humans as a function of time post-oral intake. SREM: structurally related (−)-epicatechin metabolites. 5C-RFM: 5-carbon ring fission metabolites. 3/1C-RFM: 3- and 1-carbon-side chain ring fission metabolites. The structures of the most abundant (−)-epicatechin metabolites present in the systemic circulation and in urine are depicted.[8]
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