title: Molecular organization of antifungal antibiotic amphotericin B in lipid monolayers studied by means of Fluorescence Lifetime Imaging Microscopy.
abstract: Amphotericin B (AmB) is a life-saving polyene antibiotic used to treat deep-seated mycotic infections. Both the mode of therapeutic action as well as toxic side effects are directly dependent on molecular organization of the drug. Binding of AmB to lipid monolayers formed with dipalmitoylphosphatidylcholine, pure and containing 40 mol% cholesterol or ergosterol, the sterols of human and fungi respectively, has been examined by means of Fluorescence Lifetime Imaging Microscopy. AmB emits fluorescence with the characteristic lifetimes dependent on actual molecular organization: tau(M2) < or = 10 ps and tau(M1) = 0.35 ns in the monomeric state, the emission from the S(2) and the S(1) states respectively and tau(D) = 14 ns and tau(A) = 3.5 ns in the form of a dimer and associated dimers respectively. Analysis of the Langmuir-Blodgett films reveals that AmB binds to the lipid membranes and to the cholesterol-containing lipid membranes preferentially in the form of associated dimers. The same form of AmB appears in the membranes containing ergosterol but additionally the monomers and dimers of the drug can be observed, which can severely affect molecular organization of the lipid membrane. The results are discussed in terms of selectivity of AmB towards the ergosterol-containing biomembranes of fungi.
authors.affiliation: Department of Biophysics, Institute of Physics, Maria Curie-Sklodowska University, 20-031 Lublin, Poland. wieslaw.gruszecki@umcs.pl
authors.forename: Wieslaw I
authors.initials: WI
authors.lastname: Gruszecki
authors.forename: Rafał
authors.initials: R
authors.lastname: Luchowski
authors.forename: Mariusz
authors.initials: M
authors.lastname: Gagoś
authors.forename: Marta
authors.initials: M
authors.lastname: Arczewska
authors.forename: Pabak
authors.initials: P
authors.lastname: Sarkar
authors.forename: Monika
authors.initials: M
authors.lastname: Hereć
authors.forename: Beata
authors.initials: B
authors.lastname: Myśliwa-Kurdziel
authors.forename: Kazimierz
authors.initials: K
authors.lastname: Strzałka
authors.forename: Ignacy
authors.initials: I
authors.lastname: Gryczynski
authors.forename: Zygmunt
authors.initials: Z
authors.lastname: Gryczynski
mesh_terms: D015060:1,2-Dipalmitoylphosphatidylcholine / Q000737:chemistry / Q000378:metabolism*; D000666:Amphotericin B / Q000737:chemistry / Q000378:metabolism*; D000935:Antifungal Agents / Q000737:chemistry / Q000378:metabolism*; D001665:Binding Sites; D002462:Cell Membrane / Q000737:chemistry / Q000378:metabolism; D002784:Cholesterol / Q000737:chemistry / Q000378:metabolism; D019281:Dimerization; D004875:Ergosterol / Q000737:chemistry / Q000378:metabolism; D006801:Humans; D008567:Membranes, Artificial; D008856:Microscopy, Fluorescence
chemical_list: D000935:Antifungal Agents; D008567:Membranes, Artificial; D015060:1,2-Dipalmitoylphosphatidylcholine; D000666:Amphotericin B; D002784:Cholesterol; D004875:Ergosterol