Bioautography Detection of Antimicrobial Compounds from the Essential Oil of Salvia Pachystachys

Background: Salvia species contain bioactive secondary metabolites and possess several pharmacological activities. The objective of this study was to determine the chemical composition and antimicrobial activity of essential oil from the aerial parts of Salvia pachystachys. Methods: The essential oil was obtained by means of hydrodistillation and its components were analyzed using gas chromatography and mass spectrometry (GC/MS). The minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) of the oil were determined against standard microbial strains; Staphylococcus aureus, Bacillus cereus, Escherichia coli, Pseudomonas aeruginosa and Candida albicans. Results: Thirty-six compounds were identified in the oil. The major volatile components were camphor (31.0%), 1,8-cineol (13.5%), camphene (11.7%) and α-pinene (8.0%). Oxygenated monoterpenes predominated in the S. pachystachys oil, and constituted 50.7% of the total oil composition. The values of MIC and MBC for the most sensitive strain, Staph. aureus, were 1.25 and 5.0 mg/mL, respectively, and for the most resistant strain, Pseudomonas aeruginosa and E. coli, were 5.0 mg/mL. Using bioautography assay, five compounds (camphor, 1,8-cineol, borneol, spathulenol and caryophellene oxide) were found to be responsible for the observed antimicrobial activity of the oil against S. aureus. Conclusion: These results indicated that the essential oil of S. pachystachys has moderate antimicrobial activity.