Amphotericin B (AmB) is still the most common anti-fungal agent used to treat systemic
fungal infections. It is known that this
antibiotic acts by forming pores with the
ergosterol contained in the membranes of fungi, but it also interacts with the
cholesterol contained in the membranes of eukaryotic cells, hence its toxicity. AmB may also interact with the most common oxidation products of
cholesterol found in vivo, together with interacting with biosynthetic precursors of
cholesterol, namely,
lanosterol and
7-dehydrocholesterol (7-DHC). The purpose of the present work was to study the interactions in
solution between AmB and these various
sterols, the techniques used being UV-Vis spectroscopy and differential scanning calorimetry. The results are globally interpreted in terms of the structural differences between the
sterols. We show that AmB selectively interacts with
7-DHC which, according to a recent hypothesis proposed in the literature, has been identified in connexion with a therapeutic strategy against
hepatocellular carcinomas. We find that the affinity of AmB towards
7-DHC is even greater than the affinity of the
antibiotic towards
ergosterol. We also find that AmB selectively interacts with the principal oxidation product of
cholesterol,
7-ketocholesterol, a situation that has to be taken into account when AmB is administered.