Figure 4
Identification of nystatin P1. Identification of a nystatin-like compound by liquid chromatography-tandem mass spectrometry. For each panel the lower tier corresponds to the nystatin standard and the upper tier to the Pseudonocardia P1 extract. (a) Extracted ion chromatograms for m/z 926.5 (nystatin standard) and m/z 1088.6 (nystatin P1). (b) Mass spectra averaged across the retention times indicated in panel A. (c) MS2 analysis of the molecular ions identified above. The main mode of fragmentation is the loss of water molecules (m/z 18). (d) Enlarged region of the MS2 spectra. These product ions arise from loss of the carbohydrate portion plus one to seven water molecules and most are found in the nystatin standard as well as in nystatin P1. (e) Ultraviolet spectra extracted at the retention times indicated in panel A.