title: Revisiting the mechanistic basis of the French Paradox: Red wine inhibits the activity of protein disulfide isomerase in vitro.
abstract: BACKGROUND
  Although epidemiologic evidence points to cardioprotective activity of red wine, the mechanistic basis for antithrombotic activity has not been established. Quercetin and related flavonoids are present in high concentrations in red but not white wine. Quercetin-glycosides were recently shown to prevent thrombosis in animal models through the inhibition of extracellular protein disulfide isomerase (PDI). We evaluated whether red or white wine inhibited PDI activity in vitro.
  
  
  METHODS
  Quercetin levels in red and white wines were measured by HPLC analysis. Inhibition of PDI activity by red and white wines was assessed by an insulin reduction turbidity assay at various concentrations of wine. PDI inhibition was confirmed using a reduced peptide that contained a disulfide containing peptide as a substrate. The inhibition of PDI related thiol isomerases ERp5 and ERp57 was also assessed.
  
  
  RESULTS
  We observed a dose-dependent decrease of PDI activity for a variety of red but not white wines. Red wine diluted to 3% final concentration resulted in over 80% inhibition of PDI activity by insulin reductase assay for all varieties tested. This inhibition was also observed in the peptide based assay. Red grape juice yielded similar results but ethanol alone did not affect PDI activity. Interestingly, red wine also inhibited the PDI related thiol isomerases ERp5 and ERp57, albeit to a lesser degree than PDI.
  
  
  CONCLUSIONS
  PDI activity is inhibited by red wine and grape juice, identifying a potentially novel mechanism underlying the cardiovascular benefits attributed to wine consumption.
authors.affiliation: Department of Pharmaceutical and Administrative Sciences, College of Pharmacy, Western New England University, United States.
authors.forename: Christine N
authors.initials: CN
authors.lastname: Galinski
authors.affiliation: Division of Hemostasis and Thrombosis, Beth Israel Deaconess Medical Center, Harvard Medical School, United States.
authors.forename: Jeffrey I
authors.initials: JI
authors.lastname: Zwicker
authors.affiliation: Department of Pharmaceutical and Administrative Sciences, College of Pharmacy, Western New England University, United States.
authors.forename: Daniel R
authors.initials: DR
authors.lastname: Kennedy
mesh_terms: D003116:Color; D004305:Dose-Response Relationship, Drug; D004789:Enzyme Activation / Q000187:drug effects; D000431:Ethanol / Q000737:chemistry*; D005504:Food Analysis; D005602:France; D019704:Protein Disulfide-Isomerases / Q000737:chemistry*; D011794:Quercetin / Q000737:chemistry*; D027843:Vitis / Q000737:chemistry*; D014920:Wine / Q000032:analysis* / Q000145:classification
chemical_list: D000431:Ethanol; D011794:Quercetin; D019704:Protein Disulfide-Isomerases
keywords: French Paradox; Protein disulfide isomerase; Quercetin; Red wine; Thiol isomerase