Theranostic Gallium Siderophore Ciprofloxacin Conjugate with Broad Spectrum Antibiotic Potency.

Pathogenic bacteria scavenge ferric iron from the host for survival and proliferation using small-molecular chelators, siderophores. Here, we introduce and assess the gallium(III) complex of ciprofloxacin-functionalized desferrichrome () as a potential therapeutic for bacterial infection using an in vitro assay and radiochemical, tracer-based approach. Ga- exhibits a minimum inhibitory concentration of 0.23 μM in , in line with the parent fluoroquinolone antibiotic. Competitive and mutant strain assays show that Ga- relies on -mediated transport for internalization. Ga- is potent against (3.8 μM), (0.94 μM), and (12.5 μM), while Fe- is inactive in these strains. Radiochemical experiments with reveal that Ga- is taken up more efficiently than Ga-citrate. In naive mice, Ga- clears renally and is excreted 13% intact in the urine. These pharmacokinetic and bacterial growth inhibitory properties qualify Ga- for future investigations as a diagnosis and treatment tool for infection.