title: Activities of muscadine grape skin and polyphenolic constituents against Helicobacter pylori.
abstract: OBJECTIVE
  To identify active phenolic constituents in muscadine grape skin (MGS) extracts and determine interactions among compounds while further exploring their anti-Helicobacter pylori potential in vitro.
  
  
  RESULTS
  The inhibitory effects of quercetin and resveratrol, active polyphenols identified in MGS extracts, against H. pylori were investigated. Quercetin and resveratrol significantly (P < 0.05) reduced H. pylori counts regardless of pH with minimal bactericidal concentrations of 256 and 128 μg ml(-1), respectively. MGS extracts displayed the highest efficacy, suggesting additional unidentified compounds not determined in this study. Time-course viability experiments showed a dose-dependent anti-H. pylori response to quercetin and resveratrol. Interestingly, neither quercetin nor resveratrol affected H. pylori outer membrane (OM) integrity as determined by 1-N-phenylnaphthylamine (NPN) uptake assays. However, treatment with MGS extract did increase NPN uptake, indicating OM destabilization possibly by additional unknown components. Furthermore, quercetin was found to enter H. pylori as measured by HPLC supporting intracellular drug accumulation.
  
  
  CONCLUSIONS
  Quercetin and resveratrol possess strong anti-H. pylori activity in vitro and are independent of pH. Our results also suggest that these compounds do not affect H. pylori OM integrity as previously hypothesized and that the primary antimicrobial activity of quercetin may be linked to interactions with intracellular components.
  
  
  CONCLUSIONS
  The anti-H. pylori effects of quercetin and resveratrol suggest that these compounds may be useful in the dietary prevention and/or treatment of H. pylori infection.
authors.affiliation: Department of Biological Sciences, Clemson University, Clemson, SC 29634, USA.
authors.forename: J C
authors.initials: JC
authors.lastname: Brown
authors.forename: X
authors.initials: X
authors.lastname: Jiang
mesh_terms: D015057:1-Naphthylamine / Q000031:analogs & derivatives; D000900:Anti-Bacterial Agents / Q000494:pharmacology; D002463:Cell Membrane Permeability / Q000187:drug effects; D016480:Helicobacter pylori / Q000166:cytology / Q000187:drug effects*; D006863:Hydrogen-Ion Concentration; D008826:Microbial Sensitivity Tests; D010936:Plant Extracts / Q000494:pharmacology*; D059808:Polyphenols / Q000494:pharmacology; D011794:Quercetin / Q000494:pharmacology*; D000077185:Resveratrol; D013267:Stilbenes / Q000494:pharmacology*; D027843:Vitis / Q000737:chemistry*
chemical_list: D000900:Anti-Bacterial Agents; D010936:Plant Extracts; D059808:Polyphenols; D013267:Stilbenes; C005444:N-phenyl-1-naphthylamine; D015057:1-Naphthylamine; D011794:Quercetin; D000077185:Resveratrol