Impact of extraction method on the chemical composition and antibacterial potential of Salvia fruticosa essential oil

Abstract Background Salvia fruticosa (Lamiaceae) is traditionally used to treat gastrointestinal (GIT) issues, stomach and abdominal pain, and ulcers. In this work, we aimed to extract essential oils (EOs) from the aerial parts of S. fruticosa, a plant commonly found in Egypt, and to evaluate their antibacterial activity against GIT pathogens. Methods Fresh samples’ essential oils (EOs) were extracted using hydrodistillation (HD) and headspace (HS) techniques, while dried samples’ EOs were obtained via supercritical fluid (SF) extraction. GC/MS analysis was used to analyze the EOs. Their antibacterial activity was tested against Clostridium perfringens ATCC 13124, Listeria monocytogenes ATCC 7644, Staphylococcus aureus ATCC 25923, Enterococcus faecalis ATCC 29212, Escherichia coli ATCC 8739, and Salmonella enterica ATCC 14028 through agar diffusion, microwell dilution, time-kill, and biofilm formation methods. Results The SF method yielded the highest EO (0.6 mL/100 g). In HD and SF-EOs, oxygenated compounds were predominant, accounting for 68.74% and 41.71%, respectively, while non-oxygenated compounds were most common in HS-EOs at 53.64%. Eucalyptol was the main component in both HD (43.87%) and HS-EOs (35.67%), whereas iso-caryophyllene (17.07%) and 13-epi-manoyl oxide (12.52%) were key in SF-EOs. Both HD and SF EOs showed kinetics similar to the bacterial control, indicating their potential as effective antimicrobials. Significantly, these EOs exhibited strong bactericidal activity against GIT pathogens, including C. perfringens (MBC: 500 µg/mL), L. monocytogenes (MBC: 125 µg/mL), S. aureus (MBC: 31.25 µg/mL), E. faecalis (MBC: 125 µg/mL), E. coli (MBC: 500 µg/mL), and S. enterica (MBC: 250 µg/mL). The reductions in colony-forming units (CFU/mL) were 3.8, 3.94, 7.76, 6.2, 3.7, and 5.47 log10 CFU/mL for each pathogen, with effects lasting 24 h at concentrations of 2× MIC. The MICs ranged from 31.25 to 250 µg/mL for HD and from 3.91 to 250 µg/mL for SF-EOs, demonstrating their superior antibacterial activity against GIT pathogens compared to previous research. Conclusion S. fruticose EO includes both oxygenated and non-oxygenated volatile compounds and exhibits potent antibacterial effects. They are recommended as bioactive agents for the treatment of gastrointestinal infections, although further research is required to verify their safety for clinical use.