Discovery of triazole-tethered glycinate and propanoate derivatives bearing a thiolactone moiety as quorum sensing inhibitors of Pseudomonas aeruginosa: design, synthesis, biological evaluation, and biofilm inhibition

Abstract

Quorum sensing is the bacterial communication that regulates biofilm formation, virulence, and drug resistance development. The misuse of antibiotics accelerates the emergence of resistant pathogens, highlighting the urgent need for alternative anti-virulence strategies. In this context, LasR, a key transcriptional regulator in the QS network of Pseudomonas aeruginosa, was targeted to disrupt bacterial communication and biofilm development. In the present study, we designed a library of glycinate and propanoate derivatives (n = 30), and carried out molecular docking, MM-GBSA studies, synthesized and characterized. Their QS inhibitory activity was evaluated against the P. aeruginosa MH602 reporter strain at concentrations ranging from 250 to 8 µM. The compounds exhibited 79–35% inhibition at 250 µM, retaining moderate to low activity (28–7%) at 8 µM. SAR studies indicated that the electron-withdrawing phenyl substituents on the triazole ring enhanced activity, with 11b and 10o (3-nitrophenyl) showing the highest inhibition. In silico ADME, molecular dynamics studies supported favorable LasR binding. The most active compounds were evaluated for cytotoxicity, biofilm inhibition, and suppression of pyocyanin and protease production. 10o emerged as the most promising, demonstrating strong anti-biofilm activity and significant reduction of pyocyanin, suggesting thiolactone-based triazoles as potential QS inhibitors to combat bacterial resistance.