Dependence of synergistic fungicidal activity of Cu2+ and allicin, an allyl sulfur compound from garlic, on selective accumulation of the ion in the plasma membrane fraction via allicin-mediated phospholipid peroxidation

Planta Med. 2006 Aug;72(10):875-80. doi: 10.1055/s-2006-947167.

Abstract

Allicin was effective in decreasing the lethal concentration of Cu (2+) against various fungal strains including a plant pathogen, Fusarium oxysporum, so that the minimum fungicidal concentration (MFC) of the ion for the fungus could be reduced to 2 % of that detected without allicin. In Saccharomyces cerevisiae, Cu (2+) was not apparently taken up by cells when added alone at a non-lethal concentration, whereas the ion was efficiently incorporated into cells in the presence of allicin, as in the case of cells treated with the ion at a lethal concentration. Although allicin likely increased cellular permeability to Cu (2+) due to its promotive effect on plasma membrane phospholipid peroxidation, these cell-surface events did not result in endogenous reactive oxygen species (ROS) production, a typical toxic effect of the ion. Cu (2+) was detected in the cytoplasmic fraction of cells that had been treated with the ion at a lethal concentration, whereas the ion was entrapped in the plasma membrane fraction upon their treatment with the ion at a low concentration in combination with allicin. Cu (2+) could be solubilized from the plasma membrane fraction by a procedure for the extraction of hydrophobic proteins rather than the extraction of phospholipids, suggesting its complexation with a plasma membrane protein as a result of allicin treatment. Such a subcellular localization of Cu (2+) resulted in the selective leakage of intracellular K (+), but not in the disruptive damage on the plasma membrane, and was considered to underlie the synergistic fungicidal activity of Cu (2+) and allicin.

MeSH terms

  • Antifungal Agents / metabolism
  • Antifungal Agents / toxicity*
  • Cell Membrane / drug effects*
  • Cell Membrane / metabolism
  • Cell Membrane Permeability / drug effects
  • Copper / metabolism
  • Copper / toxicity*
  • Drug Synergism
  • Fusarium / drug effects
  • Fusarium / metabolism
  • Fusarium / ultrastructure
  • Garlic / chemistry
  • Lipid Peroxidation*
  • Phospholipids / metabolism*
  • Reactive Oxygen Species / metabolism
  • Saccharomyces / drug effects
  • Saccharomyces / metabolism
  • Saccharomyces / ultrastructure
  • Sulfinic Acids / isolation & purification
  • Sulfinic Acids / toxicity*

Substances

  • Antifungal Agents
  • Phospholipids
  • Reactive Oxygen Species
  • Sulfinic Acids
  • allicin
  • Copper