Association of polyene antibiotics with sterols.

Molecular interaction between amphotericin B and sterols in non-aqueous solutions was examined quantitatively by spectroscopic methods in order to support the view point that selectivity of amphotericin B is more pronounced in the presence of ergosterol than of cholesterol. The most likely association complexes between ergosterol and amphotericin B are 4:1, 6:1 stoichiometric complex when the concentrations of amphotericin B are 3.93 x 10(-4) M, 1.94 x 10(-4) M respectively. The presence of 3 beta-OH group is necessary but not enough for the association with amphotericin B. It appears that the extent of spectral change of amphotericin B induced by complexing sterol is greater for ergosterol than cholesterol.