A new siderophore containing a 4,5-dihydroimidazole moiety was isolated from Pseudoalteromonas piscicida S2040 together with myxochelins A and B, alteramide A and its cycloaddition product, and bromo- and dibromoalterochromides. The structure of pseudochelin A was established by spectroscopic techniques including 2D NMR and MS/MS fragmentation data. In bioassays selected fractions of the crude extract of S2040 inhibited the opportunistic pathogen Pseudomonas aeruginosa. Pseudochelin A displayed siderophore activity in the chrome azurol S assay at concentrations higher than 50 μM, and showed weak activity against the fungus Aspergillus fumigatus, but did not display antibacterial, anti-inflammatory or anticonvulsant activity.
This work was supported by the EU seventh Framework Programme Project ‘PharmaSea’ (Grant agreement no. 312184). BFM acknowledges funding from the Portuguese Foundation for Science and Technology (CONT_DOUT/11/UC/405/10150/18/2008), and thanks DIPC and CFM (UPV/EHU) and the Laboratory for Advanced Computation (University of Coimbra) for support.
- Pseudochelin A