Salmonella typhimurium and pseudomonas aeruginosa respond differently to the fe chelator deferiprone and to some novel deferiprone derivatives

The ability to obtain Fe is critical for pathogens to multiply in their host. For this reason,there is significant interest in the identification of compounds that might interfere with Fe management in bacteria. Here we have tested the response of two Gram-negative pathogens, Salmonellaenterica serovar Typhimurium (STM) and Pseudomonas aeruginosa (PAO1), to deferiprone (DFP),a chelating agent already in use for the treatment of thalassemia, and to some DFP derivativesdesigned to increase its lipophilicity. Our results indicate that DFP effectively inhibits the growth ofPAO1, but not STM. Similarly, Fe-dependent genes of the two microorganisms respond differently tothis agent. DFP is, however, capable of inhibiting an STM strain unable to synthesize enterochelin,while its effect on PAO1 is not related to the capability to produce siderophores. Using a fluorescentderivative of DFP we have shown that this chelator can penetrate very quickly into PAO1, but notinto STM, suggesting that a selective receptor exists in Pseudomonas. Some of the tested derivativeshave shown a greater ability to interfere with Fe homeostasis in STM compared to DFP, whereasmost, although not all, were less active than DFP against PAO1, possibly due to interference of theadded chemical tails with the receptor-mediated recognition process. The results reported in thiswork indicate that DFP can have different effects on distinct microorganisms, but that it is possible toobtain derivatives with a broader antimicrobial action