The absorption, metabolism and excretion of flavan-3-ols and procyanidins following the ingestion of a grape seed extract by rats

CATHERINE TSANG, Cyril Auger, William Mullen, Aurelie Bornet, Jean-Max Rouanet, Alan Crozier, Pierre-Louis Teissedre

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Rats were fed a grape seed extract (GSE) containing (þ)-catechin, (2)-epicatechin and dimers, trimers, tetramers and polymeric procyanidins. Liver,
kidney, brain and gastrointestinal (GI) tract together with plasma, urine and faeces were collected over a 24 h period and their flavan-3-ol content was analysed by HPLC with tandem mass spectrometry and diode array detection. Small amounts of the GSE flavan-3-ols moved out of the stomach and into the
duodenum/jejunum, and to a greater extent the ileum 1 h after ingestion, and into the caecum after 2 h with relatively small amounts being detected in the
colon after 3 h. The GI tract contained the parent GSE flavan-3-ols and procyanidins with only trace amounts of metabolites and there were no indications
that proanthocyanidins were depolymerised in the GI tract releasing monomeric flavan-3-ols. Plasma contained exclusively catechin glucuronides and methylated glucuronide metabolites which were also detected in the liver and kidneys. These metabolites were also present in urine together with sulphated
metabolites and low amounts of the procyanidin dimers B1, B2, B3 and B4 as well as the trimer C2 and an unknown GSE trimer. The amounts of (þ)-catechin and (2)-epicatechin metabolites excreted in urine relative to the quantity of the monomers ingested were 27 and 36 %, respectively, after 24 h. This is
similar to the levels of urinary excretion reported to occur by other investigators after feeding (2)-epicatechin to rats and provides further, albeit indirect,
evidence that the procyanidin oligomers in the GSE were not depolymerised to monomers to any extent after ingestion. No convincing analytical data were
obtained for the presence of flavan-3-ol metabolites in the brain.
Original languageEnglish
Pages (from-to)170-181
Number of pages12
JournalBritish Journal of Nutrition
Issue number2
Publication statusPublished - 1 May 2005


  • Flavan-3-ols: Procyanidins: Absorption: Metabolism: Excretion: Rats: HPLC–MS –MS


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