title: Increased transport of resveratrol across monolayers of the human intestinal Caco-2 cells is mediated by inhibition and saturation of metabolites.
abstract: OBJECTIVE
  The study's aim was to investigate the dose-dependent effect of sulfation and glucuronidation on intestinal absorption of resveratrol, a dietary constituent found in grapes and various medical plants.
  
  
  METHODS
  The intestinal epithelial membrane transport kinetics and metabolism of resveratrol (10-200 microM) was studied using Caco-2 monolayers cultured in Transwells.
  
  
  RESULTS
  Along with resveratrol it was possible to identify three metabolites, namely, resveratrol-4'-O-glucuronide (M1), resveratrol 3-O-gucuronide (M2), and resveratrol-3-O-sulfate (M3) by LC/MS and NMR. Efflux of the glucuronides M1 and M2 followed Michaelis-Menten kinetics significantly favouring basolateral efflux. The predominant metabolite was the monosulfate M3, however, its formation was strongly inhibited at higher resveratrol concentrations. As biotransformation was either inhibited or saturated, total amount of resveratrol transported across the Caco-2 monolayers increased as much as 3.5-fold at 200 microM resveratrol. This value might be even higher when taking into account the high intracellular concentration of resveratrol, which accounted for up to 61% of the applied dose.
  
  
  CONCLUSIONS
  Our data demonstrate a concentration-dependent biotransformation of resveratrol in Caco-2 cells, which may also apply to human enterocytes affecting oral bioavailability.
authors.affiliation: Department of Clinical Pharmacy and Diagnostics, University of Vienna, A-1090, Vienna, Austria.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Maier-Salamon
authors.forename: Birgit
authors.initials: B
authors.lastname: Hagenauer
authors.forename: Michael
authors.initials: M
authors.lastname: Wirth
authors.forename: Franz
authors.initials: F
authors.lastname: Gabor
authors.forename: Thomas
authors.initials: T
authors.lastname: Szekeres
authors.forename: Walter
authors.initials: W
authors.lastname: Jäger
mesh_terms: D000465:Algorithms; D000818:Animals; D016588:Anticarcinogenic Agents / Q000378:metabolism*; D001693:Biological Transport, Active; D001711:Biotransformation; D018938:Caco-2 Cells; D002463:Cell Membrane Permeability; D002851:Chromatography, High Pressure Liquid; D003627:Data Interpretation, Statistical; D020719:Glucuronides / Q000378:metabolism; D006801:Humans; D008099:Liver / Q000378:metabolism; D008297:Male; D051381:Rats; D017208:Rats, Wistar; D000077185:Resveratrol; D013056:Spectrophotometry, Ultraviolet; D013267:Stilbenes / Q000378:metabolism*; D013431:Sulfates / Q000378:metabolism
chemical_list: D016588:Anticarcinogenic Agents; D020719:Glucuronides; D013267:Stilbenes; D013431:Sulfates; D000077185:Resveratrol