Antimicrobial activity and chemical composition of Thymus species and Zataria multiflora essential oils

Thymus spp. and Zataria multiflora essential oils are known in Iran as thyme oils. The chemical composition and antimicrobial activity were compared of different thyme oils from different regions of Iran. The antimicrobial activities were evaluated using disc diffusion and micro-broth dilution assays. The chemical compositions of the essential oils were analyzed. Thymol, carvacrol, para-cymene and linalool were the main components of the thyme essential oils. The geographical region can affect the chemical composition of essential oils. Aspergillus niger and Candida albicans were the most sensitive microorganisms to thyme oils. Based on minimal inhibitory concentration and minimum lethal concentration values, respectively, the best antimicrobial thyme essential oils were T. vulgaris-SH (0.27 μL/mL, 0.41 μL/mL), T. kotschyanus-SH (0.37 μL/mL, 0.64 μL/mL) and T. pubescens-SE (0.26 μL/mL, 0.75 μL/mL). In broth media, three chemotypes of thyme essential oils showed the highest antimicrobial effects: 1) linalool, thymol and carvacrol chemotype; 2) thymol, carvacrol and para-cymene; and 3) high amounts of carvacrol and para-cymene. Identification of the role of each component in the antimicrobial effect was not possible and additional software is required to draw the matrices of these reactions.