Amphotericin B-sterol complex formation and competition with egg phosphatidylcholine: a monolayer study.
The conditions of formation of amphotericin B-cholesterol or -ergosterol complexes in monolayers are investigated by the penetration into a monolayer of egg phosphatidylcholine/sterol of 14C-labelled N-fructosyl-amphotericin B dissolved in the aqueous subphase. An increase of both surface pressure and radioactivity as a function of concentration are observed simultaneously while a 'saturation' effect occurs only for the surface pressure. The experiments are not accurate enough to make conclusions about the number of actually penetrated amphotericin B molecules. Therefore, the existence of an amphotericin B-sterol complex was evidenced from a study of surface pressure area per molecule isotherm. The results indicate that a complex with a 2:1 stoichiometry is formed and that the amphotericin B-ergosterol interaction is larger than the amphotericin B-cholesterol interaction. The complex is dissociated by addition of egg phosphatidylcholine due to a competition between egg phosphatidylcholine and amphotericin B for sterol.
Saint-Pierre-Chazalet
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Laboratoire Structure et Réactivité aux Interfaces, Université Pierre et Marie Curie, Paris, France.
Thomas
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C
Dupeyrat
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Gary-Bobo
C M
CM
D000666:Amphotericin B; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002784:Cholesterol; D046911:Macromolecular Substances; D010713:Phosphatidylcholines; D013261:Sterols; D013329:Structure-Activity Relationship; D013499:Surface Properties
D046911:Macromolecular Substances; D010713:Phosphatidylcholines; D013261:Sterols; D000666:Amphotericin B; D002784:Cholesterol