Novel synthesis and anti-pathogenic properties of ensifentrine and its intermediates against Pseudomonas aeruginosa

Chronic obstructive pulmonary disease (COPD) is a progressive respiratory disorder marked by persistent lung inflammation and airway constriction. It presents a formidable global health challenge owing to its high morbidity and mortality rates. It is often aggravated by infections from pathogens such as Pseudomonas aeruginosa, a predominant pathogen that accelerates lung function deterioration and triggers frequent exacerbations. Ensifentrine (ENF) exhibits strong anti-inflammatory effects and is a selective dual inhibitor of the enzymes PDE3 and PDE4, which have been reported to be beneficial in treating COPD exacerbation. This study examined the anti-pathogenic activity of ENF against P. aeruginosa by adopting an innovative synthetic route. A series of intermediates were synthesized via the novel route, optimizing the yield and integrity of ENF. Further investigations to determine the activity of the compound against P. aeruginosa involved antibacterial and antibiofilm testing and identification of the potential mechanisms of action. Preliminary results demonstrate that ENF and its intermediate ENF^A exhibit 50-60% robust biofilm-inhibition and biofilm-eradication effects at remarkably low concentrations of 3.9 μM and 7.9 μM, respectively. Furthermore, ENF disrupts quorum sensing, leading to a 35% reduction in the production of pyoverdine and exopolysaccharide, which are two key virulence factors of P. aeruginosa. Importantly, ENF exhibits synergistic activity with ciprofloxacin, further enhancing its antimicrobial efficacy at a concentration of 0.25 μg mL^-1. This study focuses on the innovative synthesis of ENF and its promising anti-pathogenic properties, which may make it an effective adjunctive treatment for COPD caused by P. aeruginosa.