Eucalyptus globulus and Cymbopogon flexuosus essential oils are possible candidates in mitigating L. monocytogenes pathogenesis: an in silico, in vitro and in vivo study in Drosophila melanogaster

Listeria monocytogenes is a foodborne pathogen responsible for severe infections, particularly in immunocompromised individuals, and the increasing prevalence of antimicrobial resistance has intensified the search for alternative control strategies, including natural compounds such as essential oils (EOs). This study investigated the antimicrobial and anti-virulence potential of Eucalyptus globulus (EGEO) and Cymbopogon flexuosus (CFEO) against L. monocytogenes using integrated in silico, in vitro, and in vivo approaches. Chemical composition was determined by gas chromatography–mass spectrometry (GC–MS), and antioxidant activity was assessed using DPPH, ABTS, and FRAP assays. Antibacterial activity was evaluated by MIC/MBC determination and time-kill assays, while molecular docking examined interactions between EO constituents and key virulence proteins. Experimental assays assessed effects on hemolysis, motility, and biofilm formation, and an oral infection model in Drosophila melanogaster was used to analyze oxidative stress biomarkers after EO exposure. CFEO showed stronger antibacterial activity than EGEO, as indicated by MIC/MBC and motility assays. Docking analyses revealed interactions between EO compounds and listeriolysin O (LLO), consistent with experimental inhibition of hemolysis. Biofilm biomass decreased significantly at 2× MIC, whereas lower concentrations had limited effects. In vivo analyses demonstrated distinct antioxidant responses, with CFEO exhibiting greater ferric-reducing capacity, likely related to its aldehyde-rich composition. Overall, the results indicate that EGEO and CFEO can modulate L. monocytogenes virulence traits, highlighting their potential as natural agents for food safety and biocontrol applications.