Antimicrobial activity of essential oils

Abstract

Natural products have been studied aiming to understand their biological properties. Thus, this study aimed to investigate the antimicrobial activity of twenty-seven essential oils (EOs) used in aromatherapy procedures, a natural therapy with great emphasis currently used against Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa strains. The agar dilution method was carried out and minimal inhibitory concentration against 50% and 90% of strains (MIC_50% and MIC_90% values) were reported. The S. aureus strains were highly susceptible with MIC_90% from 0.21 mg/mL to black pepper (Piper nigrum) and tea tree (Melaleuca alternifolia) to 26.52 mg/mL with copaiba (Copaifera officinalis) EO. Cinnamon (Cinnamomum cassia) and clove (Syzygium aromaticum) EOs were effective against E. coli (2.0 mg/mL) while the S. aromaticum EO was against P. aeruginosa (8.29 mg/mL). Thus, the higher susceptibility of Gram-positive bacteria when compared with Gram-negative strains was found, and a large variability in the potential antibacterial has also been observed.

Keywords:

• antibacterial
• aromatherapy
• EO
• minimal inhibitory concentration

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Corrigendum

Acknowledgements

The authors are grateful to the company By Samia Aromatherapy for providing the samples of essential oils as well as by chemical analysis of the samples. Also thank Prof. Dr. Luciano Barbosa of Department of Biostatistics/Biosciences Institute, UNESP, by statistics analysis of the results from the study.