Chemical composition, antibiofilm activity, and antibacterial potential in vitro and in a zebrafish model of Myrciaria pilosa Sobral & Couto essential oil.

Ethnopharmacological Relevance: Myrciaria pilosa is a medicinal species traditionally used to treat inflammation, pain and infectious diseases. Essential oils extracted from medicinal plants have recently gained prominence as adjuvants in combating microbial resistance due to their antimicrobial properties and synergistic potential when combined with conventional antibiotics.

Aim Of The Study: Investigated the chemical composition, antibacterial activity, antibiofilm effects, and antibiotic-enhancing properties of Myrciaria pilosa essential oil.

Materials And Methods: The leaf oil was extracted through hydrodistillation and analyzed by Gas Chromatography. Antibacterial activity was evaluated through Minimum Inhibitory Concentration (MIC) testing, with subinhibitory concentrations (MIC/8) used for antibiotic combination studies. Antibiofilm action was assessed against both biofilm formation and preformed biofilm disruption. In vivo assays employed Danio rerio (zebrafish) infected with Staphylococcus aureus and Escherichia coli.

Results: Chemical analysis revealed sesquiterpenes as the predominant components, with spathulenol (26.21%) as the major compound. In vitro testing demonstrated significant antibacterial activity (MIC range: 16-512 μg/mL) and enhanced antibiotic effectiveness against S. aureus, E. coli, and Pseudomonas aeruginosa. The oil inhibited biofilm formation by up to 80% in Streptococcus mutans and showed moderate disruption of preformed biofilms. In zebrafish models, the oil reduced bacterial load without acute toxicity, outperforming gentamicin at clinically relevant concentrations (MIC and MIC/2).

Conclusion: These findings demonstrate that M. pilosa essential oil exhibits antibacterial, antibiofilm, and antibiotic-potentiating activities against multidrug-resistant bacteria. Further studies are warranted to elucidate its moleculares mechanisms and explore therapeutic applications.