A Spin Label Study of Nystatin and Amphotericin B Action on Lipid Planar Multibilayers

Abstract

EPR spectra of a cholestane probe and a stearic acid probe dissolved in egg yolk lecithin and lecithin-cholesterol planar multibilayers were observed as a function of nystatin and amphotericin B dose. Spectral components characteristic of bilayer fragmentation (tilted domains) were most evident in cholesterol-containing samples and increased with drug dose. The spectra indicate that cholesterol-containing films decrease in microscopic order as drug dose is increased. This suggests that cholesterol is involved in the commonly accepted pore-formation model for nystatin and amphotericin, since removal of cholesterol from interaction with lecithin would account for the observed decrease in order. Spectra from the cholestane probe in liposomes (with and without the drugs) were also observed.