Chemical composition and in vitro antibacterial properties of essential oils of four Thymus species from organic growth

Abstract

In organic food industry no chemical additives can be used to prevent microbial spoilage. As a consequence, the essential oils (EOs) obtained from aromatic herbs and spices are gaining interest for their potential as preservatives. The EOs of Thymus zygis, Thymus mastichina, Thymus capitatus and Thymus vulgaris obtained from organic growth, were chemically analyzed and identified by GC and GC–MS, while the agar disk diffusion and microdilution assays were used to determine their antibacterial activity. In T. mastichina EO the major compound was 1,8-cineole (51.94%) whilst in T. zygis EO the main constituent was thymol (48.59%). T. capitatus EO was characterized by high content in carvacrol (69.83%). Finally, T. vulgaris EO had a high content of linaool (44.00%).The agar disk diffusion assay, T. zygis and T. capitatus EOs showed inhibitory effects against the ten tested bacteria, while T. matichina and T. vulgaris had inhibitory effects against eight and seven tested bacteria, respectively. T. zygis and T. capitatus EOs had higher inhibition halos against all tested bacteria, at higher concentration (40μL), than T. matichina and T. vulgaris EOs. The microdilution assay, T. mastichina EO had a MIC values ranging between 3.75 and 7.5μL/mL. Whilst in the case of T. zygis, T. capitatus and T. vulgaris EOs the MIC values ranged between 1.87 and 7.5μL/mL.