Antibacterial and antioxidant activities of quercetin oxidation products from yellow onion (Allium cepa) skin

J Agric Food Chem. 2006 May 17;54(10):3551-7. doi: 10.1021/jf060251c.

Abstract

Four new quercetin-derived oxidation products (1-4) and lunularin-4-O-beta-D-glucoside (5) were isolated from a water extract of onion (Allium cepa) skin, together with 17 other known compounds. Antibacterial assays for the isolated compounds showed that 2-(3,4-dihydroxyphenyl)-4,6-dihydroxy-2-methoxybenzofuran-3-one (1) presented selective activity against Helicobacter pylori strains and 3-(quercetin-8-yl)-2,3-epoxyflavanone (4) showed antibacterial activity against MRSA and H. pylori strains at the same time that it increased susceptibility of MRSA to beta-lactams. Evaluation of antioxidant activity against DPPH for the isolated compounds showed that the new derivative compounds (1-4) and 2,5,7,3',4'-pentahydroxy-3,4-flavandione (6) are more active than quercetin.

MeSH terms

  • Anti-Bacterial Agents / isolation & purification
  • Anti-Bacterial Agents / pharmacology*
  • Antioxidants / isolation & purification
  • Antioxidants / pharmacology*
  • Bibenzyls / chemistry
  • Bibenzyls / isolation & purification
  • Biphenyl Compounds
  • Disk Diffusion Antimicrobial Tests
  • Glucosides / chemistry
  • Glucosides / isolation & purification
  • Helicobacter pylori / drug effects
  • Hydrazines
  • Methicillin-Resistant Staphylococcus aureus / drug effects
  • Molecular Structure
  • Onions / chemistry*
  • Phenols / chemistry
  • Phenols / isolation & purification
  • Picrates
  • Plant Extracts / isolation & purification

Substances

  • Anti-Bacterial Agents
  • Antioxidants
  • Bibenzyls
  • Biphenyl Compounds
  • Glucosides
  • Hydrazines
  • Phenols
  • Picrates
  • Plant Extracts
  • lunularin-4-O-beta-D-glucoside
  • 1,1-diphenyl-2-picrylhydrazyl