205 - Microbiología Molecular y Fisiología

Disrupting quorum sensing: Acalypha communis extract inhibits Pseudomonas aeruginosa virulence

Comba Ruetsch, Camila Aldana ^1,2 - Smania, Andrea Maria ^3,4 - Carpinella, Maria Cecilia ^1,2 - Luján, Adela Maria ^1,2

1) CIDIE-CONICET - Córdoba - Córdoba - Argentina.
2) Facultad de Ciencias de la Salud, Universidad Católica de Córdoba - Córdoba - Córdoba - Argentina
3) CIQUIBIC-CONICET - Córdoba - Córdoba - Argentina.
4) Departamento de Química Biológica Ranwell Caputo, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba - Córdoba - Córdoba - Argentina
Contacto: camilacombaruetsch@gmail.com

Pseudomonas aeruginosa is a Gram-negative opportunistic pathogen notorious for its ability to cause multi-drug resistant infections, particularly in immunocompromised individuals and those with cystic fibrosis. The virulence of P. aeruginosa is largely orchestrated by quorum sensing (QS), a sophisticated cell-to-cell communication system that allows bacteria to coordinate gene expression in a population density-dependent manner. One of the key QS systems in P. aeruginosa is the Rhl system, which regulates the production of various virulence factors. Given the increasing prevalence of antibiotic resistance and the limited therapeutic options for P. aeruginosa infections, there is an urgent need to identify alternative strategies to combat this pathogen. Antivirulence agents, which disarm bacteria of their virulence factors without affecting essential survival functions, have emerged as a promising alternative to traditional antibiotics. In this study, we screened 42 extracts obtained from mostly native plants from Argentina for their antivirulence activity against P. aeruginosa. Acalypha communis extract demonstrated the most potent activity, inhibiting pyocyanin production with a minimum inhibitory concentration (MIC) of 50 µg/mL. Further characterization revealed that the extract also inhibited exoprotease production and swarming motility at levels comparable to a P. aeruginosa RhlR mutant. Analysis of homoserine lactone (HSL) production showed that the extract inhibited C4-HSL but not C12-HSL, indicating its action on the Rhl QS system. The findings of this study highlight the potential of A. communis as a source of novel antivirulence compounds against P.aeruginosa. This research underscores the importance of exploring microbial ecology and natural products as a valuable source of innovative solutions to combat infectious diseases.

Palabras clave: Pseudomonas aeruginosa - quorum sensing - antivirulence - plant extracts - Acalypha communis