Polyene antibiotic action on lecithin liposomes: effect of cholesterol and fatty acyl chains

The effect of cholesterol incorporation upon amphotericin B and nystatin susceptibility of lecithin liposome systems containing various fatty acids has been studied. Cholesterol was shown to: 1) confer sensitivity to low concentrations of amphotericin B in liposomes derived from egg lecithin, and 2) suppress the amphotericin B and nystatin-induced response in liposomes derived from dipalmitoyl or distearoyl lecithins. This clear cut difference cannot be explained by mechanisms of drug action so far presented. They are discussed in connection with the possibility that susceptibility to these polyene antibiotics is related to the over-all state of the membrane organization, in particular to the over-all conformation of membrane components.