Essential oils of Thymus pulegioides and Thymus glabrescens from Romania: chemical composition and antimicrobial activity

The aim of this work was to analyse the chemical composition and antimicrobial properties of essential oils isolated from two wild-growing species of thyme (Thymus pulegioides L. and T. glabrescens Willd.) originating from different locations in Romania. The yield of essential oil was determined according to European Pharmacopoeia standards. Qualitative and quantitative analysis of the oils was performed using GC and GC/MS. The antimicrobial activity was tested by the microdilution technique against Gram-negative and Gram-positive bacteria (Escherichia coli, Salmonella typhimurium, S. enteritisdis, Enterobacter cloacae, Pseudomonas aeruginosa, Proteus mirabilis, Staphylococcus aureus, S. epidermidis, Streptococcus faecalis, Bacillus subtilis, Micrococcus luteus, M. flavus and Listeria monocytogenes) and human pathogen yeast Candida albicans. The essential oil of Thymus pulegioides was obtained in a yield of 0.7-1 % (v/d.w. herbal drug) and the main components were carvacrol (50.5-62.6 %), gamma terpinene (9.8-9.9 %) and p-cymene (5.8-7.1 %). The essential oil of T. glabrescens was obtained in a yield of 0.7 (v/d.w. herbal drug) and the main components were geraniol (55.5 %), neryl acetate (11.1 %) and beta-bisabolene (6.7 %). The essential oils inhibited microbial growth at concentrations of 10.8-27 mu l/ml.