Conformation of Polyene Antibiotic, Filipin III: CD and ¹H NMR studies

Abstract

Detailed studies on the solution conformation of polyene antibiotic, filipin III using circular dichroism (CD) and proton nuclear magnetic resonance techniques have been carried out. In dimethyl sulfoxide (DMSO), filipin III exhibits concentration dependent aggregation - monomeric at lower and oligomeric at higher concentrations of the antibiotic. At concentrations used for ¹H NMR studies (6×l0⁻³M) the molecule coexists as monomeric and oligomeric species. However, titration experiments indicated that, in a mixed solvent system of DMSO: methanol (2:3 v/v) the antibiotic exists only as a monomer. Complete ¹H NMR assignments and the conformation of the monomer filipin III have been determined by the combined use of DQFCOSY and ROESY experiments in DMSO: methanol solvent system.