Labradorins with antibacterial activity produced by Pseudomonas sp.

Abstract

The urgent need for new antibacterial drugs has led to renewed interest in microorganisms, which historically have been the main source of previously discovered antibiotics. The present study describes the discovery of two new antibacterial oxazolylindole type alkaloids, labradorins 5 (1) and 6 (2), which were isolated and characterized from two isolates of Pseudomonas sp., along with four previously known tryptophane derived alkaloids. The structures of 1 and 2 were determined by NMR spectroscopy and MS, and confirmed by synthesis. During bioassay-guided isolation using several human bacterial pathogens, 1 and 2 displayed activity towards Staphylococcus aureus and Acinetobacter baumannii. The minimal inhibitory concentrations (MIC) of compounds 1 and 2 against S. aureus were 12 mu g.mL(-1) and 50 mu g.mL(-1), respectively, whereas the MICs against A. baumannii were > 50 mu g.mL(-1). The CC50 values of compound 1 towards a liver cell line (HEP-G2) and a T-cell line (MT4) were 30 mu g.mL(-1) and 20 mu g.mL(-1), respectively, and for compound 2 were > 100 mu g.mL(-1) and 20 mu g.mL(-1), respectively. Due to the limited potency of compounds 1 and 2, along with their toxicity, the compounds do not warrant further development towards new antibiotics.

Keywords

antibiotics; secondary metabolites; labradorin; oxazolylindole; antibiotic resistant bacteria; Pseudomonas; Staphylococcus aureus; Acinetobacter baumannii

Published in

Molecules
2017, volume: 22, number: 7, article number: 1072

SLU Authors

• Broberg, Anders

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

• Bjerketorp, Joakim

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

• Andersson, Pierre

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

• Levenfors, Jolanta

  • Department of Molecular Sciences, Swedish University of Agricultural Sciences
    

Associated SLU-program

AMR: Bacteria

Global goals (SDG)

SDG3 Good health and well-being

UKÄ Subject classification

Microbiology
Medicinal Chemistry
Organic Chemistry

Publication identifier

• DOI: https://doi.org/10.3390/molecules22071072

Permanent link to this page (URI)

https://res.slu.se/id/publ/83306