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Structural characterization of the interaction of the polyene antibiotic Amphotericin B with DODAB bicelles and

Tiago R Oliveira1, Carlos R Benatti, M Teresa Lamy

  • 1Universidade de Sao Paulo, Sao Paulo, Brazil.

Biochimica Et Biophysica Acta
|August 16, 2011
PubMed

Insights

This study characterizes Amphotericin B (AmB) in DODAB bicelles, finding monomeric AmB binds to bicelle edges. This binding mechanism may reduce AmB toxicity and enhance antifungal efficacy.

Area of Science:

  • Biochemistry
  • Materials Science
  • Pharmacology

Background:

  • Amphotericin B (AmB) is a vital antifungal drug but causes significant nephrotoxicity.
  • Drug aggregation state is linked to Amphotericin B's toxicity and efficacy.
  • Formulating Amphotericin B with amphiphiles aims to improve its therapeutic index.

Purpose of the Study:

  • To structurally characterize Amphotericin B (AmB) when formulated with sonicated dioctadecyl dimethylammonium bromide (DODAB) aggregates.
  • To investigate the binding site and effects of monomeric AmB within DODAB bicelles.
  • To propose a novel method for quantifying amphiphile-bound monomeric AmB.

Main Methods:

  • Characterization of sonicated DODAB dispersions using biophysical techniques.
  • Solubility studies of monomeric AmB in DODAB bicelles versus vesicles.
  • Development and application of a new optical parameter for AmB-amphiphile binding.
  • Theoretical simulations of spin-labeled DODAB bicelles to probe AmB binding interactions.

Main Results:

  • Sonicated DODAB dispersions were confirmed to form bicelles.
  • Monomeric Amphotericin B exhibited higher solubility in DODAB bicelles compared to DODAB vesicles.
  • A new optical parameter was developed to estimate amphiphile-bound monomeric AmB.
  • Simulations revealed monomeric AmB preferentially binds to DODAB bicelle edges, rigidifying the structure and reducing local polarity.

Conclusions:

  • Monomeric Amphotericin B preferentially binds to the disordered lipid edges of DODAB bicelles.
  • This specific binding interaction offers a potential strategy for developing less toxic and more effective Amphotericin B formulations.
  • The findings support the use of bicelle-forming lipids, including natural lipid mixtures, as carriers for Amphotericin B.

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