Protective effect of iridals from saponin injury in Candida albicans cells

Spirostanol saponin permeabilization of Candida albicans cells resulted in phosphate (Pi) leakage from these cells. Pre-incubation of C. albicans suspension cultures with ergosterol or cycloiridals inhibited Pi leakage when cells were subjected to saponins. Saponins were shown to precipitate ergosterol but not cycloiridals. Inhibition of Pi leakage in the presence of cycloiridals could thus be due to their incorporation into cell membranes. Cycloiridals, which were previously shown to modify fluidity parameters in artificial phospholipid bilayers, seem in vivo to have a protective effect on membranes against surfactant (saponin) injury.