Bactericidal and antioxidant effects of essential oils from Satureja montana L., Myristica fragrans H. and Cymbopogon flexuosus

The extraction and characterization of the essential oils (EO) from Satureja montana L., Myristica fragrans H. and Cymbopogon flexuosus and the determination of their antibacterial and antioxidant activities were achieved. The EO were identified by gas chromatography/mass spectrometry and quantified by gas chromatography using a flame ionization detector. The antibacterial potential against Escherichia coli and Staphylococcus aureus was evaluated by cell susceptibility assays and by scanning electron microscopy. The antioxidant activity was evaluated by the 2,2‐diphenyl‐1‐picrylhydrazyl assay, by β‐carotene bleaching and by determining the reducing power. Borneol (36·18%), γ‐terpineol (12·66%) and carvacrol (11·07%) were the principal components in the EO from S. montana, and sabinene (49·23%) and α‐pinene (13·81%) were found in the EO from M. fragrans. Geranial (59·66%) and neral (38·98%) isomers were the only major components in the EO from C. flexuosus. The EO from S. montana was effective against E. coli, with minimum inhibitory and bactericidal concentrations (MIC and MBC) of 6·25 µl ml−1, whereas bactericidal potential against both was observed for the EO from M. fragrans; MIC = 6·25 µl ml−1 for S. aureus and MBC = 12·5 µl ml−1 for E. coli. A significant protective role on lipid substrates in the β‐carotene bleaching assay was seen for the EO from S. montana and M. fragrans. Overall, such EO can be promising agents against pathogenic bacteria and for protecting biomolecules during oxidative stress. Significance and Impact of the Study: The study addresses natural alternatives in the selective control of pathogenic bacterial species resistant to antibiotics and the oxidative stress in infectious processes. Important results in relation to the antibacterial and antioxidant activities of essential oils from S. montana, M. fragrans. and C. flexuosus were found. Essential oils can act in the oxidative process, and they can disturb the cytoplasmic membrane by interfering with the phospholipid bilayer of the cell wall, increasing the permeability and loss of cell constituents and causing cell death of bacteria. Thus, the use of essential oils is very promising for the development of new antimicrobials.