Abstract

The essential oils from Thymus vulgaris, Salvia officinalis, and Ocimum basilicum were
extracted by hydrodistillation, characterized by gas chromatography/mass spectrometry,
and quantified by gas chromatography/flame ionization detector. The principal constituents were thymol, ρ-cymene and carvacrol (T. vulgaris); camphor, β-pinene, and 1,8-cineole
(S. officinalis); and (E)-anethole, linalool, and 1,8-cineole (O. basilicum). The essential oil from
T. vulgaris was the most effective, forming inhibition halos of 46.16 ± 0.16 and 26.38
± 0.33 mm, respectively, for Salmonella choleraesuis and Listeria monocytogenes. This essential oil was also more effective against S. choleraesuis, with a minimum inhibitory concentration of 8.85 mg mL
1
, and a minimum inhibitory concentration of 17.71 mg mL
1 for
L. monocytogenes. No bactericidal activity against S. choleraesuis and L. monocytogenes was
observed for the essential oils from S. officinalis, and O. basilicum. Scanning electron micrographs showed that the addition of essential oils left the bacterial cells damaged and
deformed. Significant 2,2-diphenyl-1-picrylhydrazyl free radical scavenging capacity and
lipid substrate protection were observed in the β-carotene bleaching assay for the essential oil from T. vulgaris, with IC50 of 231.13 ± 0.53 and 15.25 ± 0.38 μg mL
1
, respectively.
A dose-dependent relationship between antioxidant activity and concentrations was
observed in the tests. Toxicities of LC50 = 1.24, 3.51 and 1.19 mg mL
1 against
Drosophila suzukii flies, respectively, were observed for the essential oils from T. vulgaris,
S. officinalis, and O. basilicum. Results suggest that essential oils can be promising
antioxidant agents, insecticides, and inhibitors of pathogenic bacteria.