Antibacterial and QS Inhibition by Schinus molle Essential Oil: Chemical Profiling and Docking Against S. aureus.

Background: Owing to the worldwide issues of resistance to antibiotics and the role of quorum sensing in the regulation and development of bacteria (Staphylococcus aureus) virulence factors, scientific communities explore alternatives to drugs, such as medicinal plants' essential oils. This study was performed to evaluate the antivirulence, biofilm retardation, and quorum sensing (QS) retarding activities of Schinus molle essential oil (SMEO) against the pathogenic S. aureus and its Agr mutant strains and evaluate the antiquorum activity of S. molle EO compounds.

Methods: The chemical composition of SMEO was measured using the Fourier-transform infrared spectroscopy (FT-IR) and gas chromatographymass spectrometry (GC-MS) approaches. Antimicrobial activity was studied using agar disc diffusion.

Results: Notably, the results revealed 20 compounds with limonene (35.82%) and α-phellandrene (19.13%) dominant constituents. The antibacterial effects were assessed via the agar dilution method, while anti-QS activity was examined using Chromobacterium violaceum CECT 494. Remarkably, the SMEO exhibited strong bactericidal potentials, effectively destroying the bacterial cells within 24 hours duration with inhibition zones reaching up to (34.33 ± 0.1 mm). Additionally, the SMEO inhibited staphyloxanthin formation, exopolysaccharide (EPS), and biofilm formation with significant reduction up to 96.27%, 93.78%, and 92.87%, respectively. Likewise, slime production and motility were highly affected by SMEO. These were done with extraordinary declines witnessed in a concentration-dependent pattern. Furthermore, the molecular docking analysis affirmed strong collaborations be-tween the SMEO constituents and the AgrA and thereby supporting its antivirulence capability.

Conclusions: Findings obtained from this study highlighted the promising prospects of SMEO as a potent natural compound in mitigating S. aureus virulence and biofilm formations, indicating its potential use as an alternative treatment to antibiotics.