Hybrid -Acylcysteines as Dual-Acting Matrix Disruptive and Anti-Quorum Sensing Agents Fighting Biofilms: Design, Synthesis, Molecular Docking Studies, and Assays.

Biofilms facilitate the pathogenesis of life-threatening infections by coating mucosal surfaces or invasive devices and offer protection from antimicrobial therapy and the host immune response, thus increasing mortality rates and financial burden. Herein, new hybrid -acylcysteines (NAC) incorporating selected acyl groups from organic acids and their derivatives, which are capable of quenching pathogen quorum sensing (QS) systems, were designed and their antibiofilm activity and anti-QS were evaluated. -acylcysteines () were synthesized and characterized by H NMR and C NMR, and their purity was confirmed by elemental analyses. -(4-Hydroxy-3,5-dimethoxybenzoyl)-l-cysteine () and -(4-methoxybenzoyl)-l-cysteine () showed a higher antibiofilm activity against PAO1 biofilms than the rest of the targets and the standard NAC. They showed 83 and 82% inhibition of biofilms at 5 mM and eradicated mature biofilms at 20 mM concentrations (NAC biofilm inhibition = 66% at 10 mM and minimum biofilm eradication concentration = 40 mM). This was confirmed via visualizing adherent biofilm cells on catheter pieces using scanning electron microscopy. In the same vein, both and showed the highest docking score with the QS signal receptor protein LasR (-7.8), which was much higher than that of NAC (-5) but less than the score of the natural agonist -(3-oxododecanoyl)-l-homoserine (OdDHL) (-8.5). Target (5 mM) decreased the expression of quorum sensing encoding genes in PAO1 strain by 53% for , 47% for and , and 29% for , lowered PAO1 pyocyanin production by 76.43%, completely blocked the proteolytic activity of PAO1, and did not affect PAO1 cell viability. Targets and may find applications for the prevention and treatment of biofilm-mediated local infections of the skin, eye, and wounds. -(4-Methoxybenzoyl)-l-cysteine is a promising dual-acting matrix disruptive and anti-QS antibiofilm agent for further investigation and optimization.