Identification of streptothricin class antibiotics in the early stage of antibiotics screening by electrospray ionization mass spectrometry

Abstract

Several streptothricin antibiotics have been studied by tandem mass spectrometry. The dominant product ions were derived from the C7-N bond cleavage which lead to lose streptolidine from the [M+H]+. The fragmentation pathways of key ions were described and certained by parent scan. According to the generalized principles, streptothricin isomers could be distinguished easily by the difference of CID spectra. A facile method based on ion-pair RP-HPLC coupled with electrospray ionization tandem mass spectrometry has been established for the analysis of streptothricins in the fermentation broth of Streptomyces qinlingensis. A total of 19 streptothricin-like compounds were identified or tentatively characterized based on their mass spectral data, and in which 11 were the first reported compounds. This could be used as an important de-replication method in the programs of screening novel antibiotics. © Japan Antibiotics Research Association.