Antibacterial and Antibiofilm Formation Activities of Pyridinium-Based Cationic Pillar[5]arene Against Pseudomonas aeruginosa

An omnipresent pathogenic bacterium, Pseudomonas aeruginosa (P. aeruginosa PAO1), is easy to contaminate environmental water or foods, causing daily food spoilage and infections. The biofilm-forming ability and bacterial resistance of P. aeruginosa PAO1 make it difficult to be eradicated by traditional bacteriostatic agents. In this work, we designed and synthesized a pyridinium-based pillar[5]­arene (PP5), while trimethylammonium-based pillar[5]­arene (TP5) was used as a control compound. After clear characterization, the antibacterial and antibiofilm activities as well as the microbial resistance of TP5 and PP5 against P. aeruginosa PAO1 were extensively examined. It was revealed that PP5 exhibited good inhibition activity with the minimum inhibitory concentration (MIC) of 0.051 mmol/L, while no significant antibacterial and biofilm formation activity for TP5 against P. aeruginosa PAO1 was observed. More importantly, PP5 had negligible antimicrobial resistance even after 18th passages. A transmission electron microscope (TEM) showed that PP5 could physically disrupt the cell membranes, causing the leakage of internal constituents, which is possibly ascribed to the synergistic penetrability and π–π interactions of strain, thus greatly reduced the development of bacterial resistance. Overall, the presented studies indicated that pyridinium moieties could facilitate the cationic pillar[5]­arene to generate surprising antibacterial and antibiofilm formation ability against P. aeruginosa PAO1.