Antibacterial and Antibiofilm Potential of Ethanolic Extracts of Duguetia vallicola (Annonaceae) against in-Hospital Isolates of Pseudomonas aeruginosa

Pseudomonas aeruginosa is an opportunistic pathogen, especially dominant in people with cystic fibrosis; the drug resistance expressed by this pathogen and its capacity for adaptation generate a great challenge for its treatment and control, increasing morbidity and mortality rates globally. In this sense, the search for new treatment alternatives is imminent today, with products of plant origin being an excellent alternative to be used. The objective of this research was to evaluate the antibacterial and antibiofilm potential and to explore the possible effect of ethanolic extracts of wood and bark of Duguetia vallicola on the cell membrane. Microdilution assays showed inhibition of bacterial growth by more than 50%, with the lowest concentration evaluated (62.5μg/mL) of both extracts. Furthermore, we report the ability of both extracts to inhibit mature biofilms, with inhibition percentages between 48.4% and 93.7%. Intracellular material leakage experiments (260/280 nm), extracellular pH measurement, and fluorescence microscopy with acridine orange (AO) and ethidium bromide (EB) showed cell membrane damage. This indicates that the anti-bacterial action of ethanolic extracts of D. vallicola is associated with damage to the integrity of the cell membrane and consequent death of these pathogens. These results serve as a reference for future studies in establishing the mechanisms of action of these extracts.