Dissociation of Nystatin and Amphotericin Analogues: Characterisation of Minor Anti-Fungal Macrolides

Abstract

Tandem mass spectrometry combined with Fourier transform ion cyclotron resonance (FT-ICR) has been the basis for rationalizing the fragmentation mechanisms of anti-fungal macrolides nystatin A1, amphotericin B and pimaricin. The positive ion mass spectra were not informative, however, the dissociation of deprotonated molecules led to structurally significant ring-opened fragments. Using this approach of tandem FT-ICR mass spectrometry and electrospray ionisation coupled with high-performance liquid chromatography (HPLC), 11 macrolide natural analogues or degradation products were characterised in the nystatin mixture.