Chemical variation of leaf essential oil at different stages of plant growth and in vitro antibacterial activity of Thymus vulgaris Lamiaceae, from Iran

The essential oil components of the leaves were isolated by hydrodistillation from Thymus vulgaris (T.) Lamiaceae, at different stages of plant growth. The essential oils from T. Lamiaceae leaves were obtained in yields of 0.83–1.39% (w/w). The oils were studied by gas chromatography mass spectrometry (GC/MS) and thirty-six components were identified in the oil. The major components in the leaf oils were: thymol (38.23–63.01%), o-cymene (5.56–15.47%), γ-terpinene (4.43–7.17%), borneol (1.72–6.65%), 4-terpineol (1.24–5.16%) and 1,8-cineole (0.09–1.54%). The results showed that the oil yield and the major constituents' percentage of the leaf were different at different stages of plant growth. The essential oils of T. Lamiaceae leaves were tested against five strains of Gram positive bacteria (g+) and five strains of Gram negative bacteria (g−). The average minimal inhibitory concentration (MIC) and minimal bactericidal concentration (MBC) of essential oils were determined using agar dilution method against the organisms by agar dilution method.