Interactions between amphotericin B 3-( N', N'-dimethylamino) propyl amide and cellular membrane components in Langmuir monolayers

In this paper we present the characteristics of the Langmuir monolayers formed by amphotericin B 3-( N', N'-dimethylamino) propyl amide (AMA) that is a derivative of amphotericin B (AmB), a polyene antifungal antibiotic. Also, the interactions of AMA with sterols (cholesterol, ergosterol) and a phospholipid ( l-α Phosphatidylcholine dipalmitoyl — DPPC) were studied in the mixed films. The experiments were based on measurements of the surface pressure during film compression and the results were analyzed with the isothermal compressibility, the excess area per molecule, the excess free energy of mixing and the total free energy of mixing values. It was found that the ionic state of AMA molecule affects its biological properties. Moreover, the size of the antibiotic molecule influences its interactions with sterols. Thus, AMA that is larger molecule than AmB reflects the higher selectivity as compared to the parent antibiotic. Interestingly, contrary to AmB derivatives investigated previously, the interactions between DPPC and AMA are not important from the point of view of biological properties of the antibiotic studied.