Evaluation of the antibacterial and inhibitory activity of the NorA and TetK efflux pumps of Staphylococcus aureus by p-coumaric acid

• Published in: Microbial pathogenesis 2025-03, Vol.200, p.107318, Article 107318
• Main Authors: de Sousa Silveira, Zildene, Macêdo, Nair Silva, Menezes Dantas, Débora de, Rodrigues dos Santos Barbosa, Cristina, Muniz, Débora Feitosa, Morais Oliveira-Tintino, Cícera Datiane de, Relison Tintino, Saulo, Alencar, Gabriel Gonçalves, Marinho, Emmanuel Silva, Rocha, Matheus Nunes da, Marinho, Marcia Machado, Santos, Hélcio Silva dos, Coutinho, Henrique Douglas Melo, Cunha, Francisco Assis Bezerra da, Silva, Márcia Vanusa da
• Format: Article
• Language: English
• Subjects: ADMET; Bacterial resistance; Efflux inhibitors; Molecular docking; Phenolic acid
• ISSN: 0882-4010; 1096-1208; 1096-1208
• DOI: 10.1016/j.micpath.2025.107318

The NorA and TetK efflux pumps mediate resistance to fluoroquinolone and tetracycline antibiotics by actively extruding these compounds and reducing their intracellular concentrations. Consequently, intense research has focused on inhibiting these efflux mechanisms using antimicrobial agents derived from natural or synthetic sources. This study used Fourier transform infrared spectroscopy (ATR-FTIR) to analyze the various functional groups present in p-coumaric acid. We also investigated the antibacterial activity of p-coumaric acid on strains of Staphylococcus aureus carrying the NorA and TetK efflux pumps, as well as the compound's ability to increase the fluorescence of ethidium bromide (EtBr) and Sytox Green. In addition, the interactions of this compound with NorA were analyzed using molecular docking, and its pharmacokinetic properties were evaluated using ADMET (Absorption, Distribution, Metabolism, Excretion and Toxicity) modeling. The results revealed that p-coumaric acid exhibited no direct antibacterial activity against the tested Staphylococcus aureus strains. However, significant reductions in the minimum inhibitory concentrations (MICs) of norfloxacin and EtBr, both used as NorA substrates, were observed when combined with p-coumaric acid. It was also observed that p-coumaric acid increased the fluorescence emission of EtBr and Sytox Green in strains 1199 and 1199B, suggesting the inhibition of the efflux mechanism and enhanced membrane permeabilization in S. aureus. The in silico analysis demonstrated that p-coumaric acid exhibits a favorable binding energy with NorA, comparable to that of chlorpromazine. These results position p-coumaric acid as a promising antibiotic adjuvant and efflux inhibitor in strains harboring NorA. •p-coumaric acid potentiates the activity of norfloxacin and ethidium bromide.•p-coumaric acid increased fluorescence emission by ethidium bromide.•p-coumaric acid increased membrane permeabilization of Staphylococcus aureus.•p-coumaric acid has a favorable binding energy with NorA, similar to chlorpromazine.•p-coumaric acid has high oral bioavailability and metabolic stability.