Structure of the Antifungal Nucleotide Antibiotic Phosmidosine

Article abstract of DOI:10.1021/jo00056a017

The structure of phosmidosine (1), a novel proline-containing nucleotide antibiotic from Streptomyces durhameusis, active against the pathogenic fungus Botrytis cinerea, was determined by mass spectrometry and NMR spectroscopy.Homologs 2, 3, and the isomer 4 were detected and characterized using approaches based principally on tandem mass spectrometry and combined liquid chromatography-mass spectrometry which permitted assignment of most structural features directly in the crude isolate without prior isolation of individual components.Conversion of 1-4 to the O-isopropylidene derivatives 1a-4a by a microscale procedure resulted in enhanced fast atom bombardment ionization (FAB) signal to background sensitivity.Collision-induced dissociation mass spectra were aquired from molecular ions and ion source-generated fragment ions and used in conjunction with FAB-deuterium exchange methods for the assignment of structural differences between 1a-4a.