Antimicrobial activity of essential oils.

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 (MIC50% and MIC90% values) were reported. The S. aureus strains were highly susceptible with MIC90% 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. [ABSTRACT FROM AUTHOR]