Effect of fatty acids on action of polyene antibiotics.

Fatty acids cause a decrease in the absorption spectra of the antifungal polyene macrolide antibiotics nystatin, filipin, candicidin, and amphotericin B. For nystatin, filipin, and candicidin, this decrease in absorption could be correlated with the activity of the fatty acids in protecting the yeast Saccharomyces cerevisiae against the action of these antibiotics. With amphotericin B a correlation was observed between the decrease in absorption caused by certain derivatives of fatty acids and the protective action of these derivatives against the activity of amphotericin B on yeast. It is concluded that, like the sterols, fatty acids also interact with the polyene antibiotics and thereby reduce their effective concentrations.