Deferasirox (ExJade): A Fluorescent Pro-Chelator Active Against Antibiotic Resistant Bacteria

Deferasirox, ExJade, an FDA-approved treatment for iron overload disorders has been shown to inhibit the growth of both gram-positive and -negative bacteria through iron (Fe(III)) chelation. Modification of the ExJade framework led to the identification of a new fluorescent platform ExPh and ExBT. Functionalization of the phenol moieties on ExBT with phosphate units afforded a ratiometric fluorescent pro-chelator (ExPhos), which was effective in the inhibition of two clinically relevant antibiotic-resistant bacteria, (MRSA (ATCC 43300) and VRE (ATCC 51299)), and allowed the fluorescent imaging of MRSA. Remarkably, this pro-chelation strategy proved selective towards bacteria with no cytotoxicity observed for ExPhos treated A549 cells (72 h incubation). This work represents a new pro-chelator antibiotic strategy that can be modified with a chosen reactive chemical trigger to provide a diagnostic signal in conjunction with a therapeutic response with a potential of minimal off-target toxicities.