The Electrospray Ionization - Mass Spectra of Erythromycin A Obtained from a Marine Streptomyces sp. Mutant

Abstract

In our ongoing search for production improvements of bioactive secondary metabolites from marine Streptomyces through the induction of mutations using UV light, out of 145 isolates, mutant 10/14 was able to produce potent antibacterial metabolites other than the parent strain as established by chromatographic analysis. Up-scaling fermentation of mutant 10/14, followed by working up and isolation delivered five metabolites, phenazine, 1-acetyl-beta -carboline, perlolyrin and erythromycin A, along with an oily substance. The latter two compounds were responsible for the antibacterial activity of the strain. In this article, we discuss with the mutation of the marine Streptomyces sp. AH2, bioactivity evaluation, fermentation and isolation of the microbial metabolites. Moreover, we study to first time in detail the 1D and 2D NMR and ESI MS data including ESI MS(2) and MS(3) patterns combined with HRESI MS of erythromycin A.

Keywords: ESI-MS/MS; Marine Streptomyces mutation; bioactivity evaluation; erythromycin A.

Fig. 1

Structural formula of the macrolides 1-7 beside to the sugars A and B.

Fig. 2a

ESI-MS-MS fragmentations of erythromycin A(1)

Fig. 2b

(+)-ESI-MS-MS fragmentations of erythromycin A (1)

Fig. 3

HMBC (→) and ¹H, ¹H COSY (↔) derived connectivities of erythromycin A (1)