title: Tea catechin auto-oxidation dimers are accumulated and retained by Caco-2 human intestinal cells.
abstract: Despite the presence of bioactive catechin B-ring auto-oxidation dimers in tea, little is known regarding their absorption in humans. Our hypothesis for this research is that catechin auto-oxidation dimers are present in teas and are absorbable by human intestinal epithelial cells. Dimers (theasinensins [THSNs] and P-2 analogs) were quantified in commercial teas by high-performance liquid chromatography-mass spectrometry. (-)-Epigallocatechin (EGC) and (-)-epigallocatechin gallate (EGCG) homodimers were present at 10 to 43 and 0 to 62 mumol/g leaf, respectively. The EGC-EGCG heterodimers were present at 0 to 79 mumol/g. The potential intestinal absorption of these dimers was assessed using Caco-2 intestinal cells. Catechin monomers and dimers were detected in cells exposed to media containing monomers and preformed dimers. Accumulation of dimers was significantly greater than monomers from test media. Three-hour accumulation of EGC and EGCG was 0.19% to 0.55% and 1.24% to 1.35%, respectively. Comparatively, 3-hour accumulation of the EGC P-2 analog and THSNs C/E was 0.89% +/- 0.28% and 1.53% +/- 0.36%, respectively. Accumulation of P-2 and THSNs A/D was 6.93% +/- 2.1% and 10.1% +/- 3.6%, respectively. The EGCG-EGC heterodimer P-2 analog and THSN B 3-hour accumulation was 4.87% +/- 2.2% and 4.65% +/- 2.8%, respectively. One-hour retention of P-2 and THSNs A/D was 171% +/- 22% and 29.6% +/- 9.3% of accumulated amount, respectively, suggesting intracellular oxidative conversion of THSNs to P-2. These data suggest that catechin dimers present in the gut lumen may be readily absorbed by intestinal epithelium.
authors.affiliation: Department of Food Science, Purdue University, West Lafayette, IN 47907, USA.
authors.forename: Andrew P
authors.initials: AP
authors.lastname: Neilson
authors.forename: Brian J
authors.initials: BJ
authors.lastname: Song
authors.forename: Teryn N
authors.initials: TN
authors.lastname: Sapper
authors.forename: Joshua A
authors.initials: JA
authors.lastname: Bomser
authors.forename: Mario G
authors.initials: MG
authors.lastname: Ferruzzi
mesh_terms: D001578:Benzopyrans / Q000737:chemistry / Q000378:metabolism; D018938:Caco-2 Cells; D028241:Camellia sinensis / Q000737:chemistry*; D002392:Catechin / Q000031:analogs & derivatives / Q000737:chemistry / Q000378:metabolism*; D002853:Chromatography, Liquid; D019281:Dimerization; D004847:Epithelial Cells / Q000378:metabolism*; D006801:Humans; D007408:Intestinal Absorption; D007413:Intestinal Mucosa / Q000378:metabolism*; D013058:Mass Spectrometry; D010084:Oxidation-Reduction; D010636:Phenols / Q000737:chemistry / Q000378:metabolism; D011108:Polymers / Q000737:chemistry / Q000378:metabolism; D013662:Tea / Q000737:chemistry*
chemical_list: D001578:Benzopyrans; D010636:Phenols; D011108:Polymers; D013662:Tea; C481298:theasinensin A; C020845:P-2; D002392:Catechin