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.
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.
Ogita
Akira
A
Institute for Health and Sport Sciences, Osaka City University, Osaka, Japan.
Fujita
Ken-Ichi
K
Taniguchi
Makoto
M
Tanaka
Toshio
T
D000935:Antifungal Agents / Q000378:metabolism / Q000633:toxicity*; D002462:Cell Membrane / Q000187:drug effects* / Q000378:metabolism; D002463:Cell Membrane Permeability / Q000187:drug effects; D003300:Copper / Q000378:metabolism / Q000633:toxicity*; D004220:Disulfides; D004357:Drug Synergism; D005670:Fusarium / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D005737:Garlic / Q000737:chemistry; D015227:Lipid Peroxidation; D010743:Phospholipids / Q000378:metabolism*; D017382:Reactive Oxygen Species / Q000378:metabolism; D012440:Saccharomyces / Q000187:drug effects / Q000378:metabolism / Q000648:ultrastructure; D013441:Sulfinic Acids / Q000302:isolation & purification / Q000633:toxicity*
D000935:Antifungal Agents; D004220:Disulfides; D010743:Phospholipids; D017382:Reactive Oxygen Species; D013441:Sulfinic Acids; C006452:allicin; D003300:Copper