Among the current antibiotics in clinical practice, fluoroquinolone ciprofloxacin (CPX) stands out for its broad-spectrum antimicrobial activity. However, the emergence of multidrug-resistance phenomena significantly undermines its therapeutic efficacy, with several bacterial strains, including Pseudomonas aeruginosa, acquiring a resistant phenotype, making them no longer susceptible to CPX. Being a leading opportunistic bacterium, this pathogen is reported to cause severe, often life-threatening infections, especially in hospitalized immunocompromised patients. Pieces of evidence have highlighted the huge potential of targeting P. aeruginosa (Ps) carbonic anhydrase (CA, EC: 4.2.1.1) metalloenzymes, which play a critical role in the bacterium virulence and have recently emerged as attractive innovative pharmacological targets for the development of novel antibacterial agents.
This work provides a response to this challenge, based on the design and development of an extensive library of CPX hybrid derivatives incorporating recognized CA-inhibiting chemotypes, i.e., benzenesulfonamides and coumarins. Enzymatic and biological assays revealed the potent nanomolar inhibition of PsCA activity, along with remarkable antibacterial effects, including bactericidal and anti-biofilm properties for some compounds. Suboptimal PK properties for two representative compounds emerged from a preliminary study in vitro. Moreover, no toxicity was observed in the 3R-compliant Galleria mellonella larvae model, indicating a safety profile. In silico docking simulations and crystallization studies were helpful to gain valuable insights into the binding modes of such compounds to CA enzymes, guiding further optimization efforts.
Altogether, our findings underscore the potential of CPX CA-inhibiting hybrids as a valuable strategy to fight P. aeruginosa infections, particularly in the context of rising antibiotic resistance.

Reference
Marinacci B, D'Agostino I, Angeli A, Carradori S, Melfi F, Grande R, Corsiani M, Ferraroni M, Agamennone M, Tondo AR, Zara S, Puca V, Pellegrini B, Vagaggini C, Dreassi E, Patrauchan MA, Capasso C, Nicolotti O, Carta F, Supuran CT. J Med Chem. 2024 Nov 14;67(21):19077-19102. doi: 10.1021/acs.jmedchem.4c01555.