Identification of the chemical composition of six essential oils with mass spectroscopy and evaluation of their antibacterial and antioxidant potential

This study determined the chemical composition of Cinnamomum verum J.Presl, Cistus ladaniferus L., Laurus nobilis L., Senecio anteuphorbuim, Boswellia serrata Roxb. ex Colebr. and Schinus molle L. essential oils (EOs) by gas chromatography-mass spectrometry. Moreover, the six EOs were screened in order to reveal their antibacterial and antioxidant activities. They were initially tested against six pathogenic bacteria: Staphylococcus aureus (MRSA: methicillin-resistant Staphylococcus aureus), Escherichia coli (ESBL: extended-spectrum β-lactamases), Enterococcus faecalis (VRE: vancomycin-resistant enterococcus), Klebsiella pneumoniae (CRK: carbapenem-resistant klebsiella), clinical isolate Staphylococcus aureus and Escherichia coli ATCC 25922. Then, the antioxidant effect was assessed by β-carotene-linoleic acid. Cinnamomum verum J.Presl, Cistus ladaniferus L. and Laurus nobilis L. exhibited the greatest antibacterial activity except Boswellia serrata Roxb. ex Colebr. oil. But this last one showed the highest antioxidant activity (85.75%) comparable to that of BHT (98.25%). The principal component analysis between the antibacterial activity and the twenty major components of six EOs revealed that α-pinene, β-pinene, 4-carene, α-phellandrene, 1,8-cineole, linalool, 1,3,8-p-menthatriene, α-terpineol, cinnamyl alcohol and cinnamaldehyde are responsible for their antibacterial activity against multi-resistant strains. From this study, the results obtained show that the EOs may constitute an alternative to the emergence of multidrug-resistant bacteria.