GaSal-2: A Water-Soluble Antipseudomonal Agent Targeting the Extracellular Hemophore HasAp

Area of Science:

• Microbiology
• Infectious Diseases
• Drug Discovery

Background:

• Multidrug-resistant *Pseudomonas aeruginosa* poses a significant threat, necessitating novel antibiotic development.
• The *hasAp* and *hasR* genes are crucial for *P. aeruginosa* virulence and survival during infection.
• Previous research identified a gallium complex, GaSal, with antipseudomonal activity targeting HasAp.

Purpose of the Study:

• To develop and evaluate a water-soluble gallium complex, GaSal-2, as a potential antibiotic against *P. aeruginosa*.
• To investigate the mechanism of action of GaSal-2, including its binding to HasAp and effects on bacterial signaling.
• To assess the efficacy and safety of GaSal-2 in vitro and in a preclinical infection model.

Main Methods:

• Synthesis and characterization of the water-soluble gallium salophen complex, GaSal-2.
• In vitro assays to evaluate GaSal-2 binding to HasAp, inhibition of *P. aeruginosa* growth, and disruption of established biofilms.
• Assessment of GaSal-2 cytotoxicity in human lung fibroblasts and hepatocytes.
• Evaluation of GaSal-2 efficacy in a murine lung infection model.

Main Results:

• GaSal-2 demonstrated tight binding to the HasAp protein.
• The complex effectively inhibited *P. aeruginosa* growth and disrupted established biofilms.
• GaSal-2 exhibited no toxicity towards human lung fibroblasts and hepatocytes.
• In vivo studies showed promising antipseudomonal effects in a murine lung infection model.

Conclusions:

• GaSal-2 is a potent, water-soluble antibiotic candidate targeting the HasAp pathway in *P. aeruginosa*.
• GaSal-2 effectively inhibits bacterial growth, disrupts biofilms, and shows a favorable safety profile.
• This novel compound represents a promising therapeutic strategy against multidrug-resistant *P. aeruginosa* infections.