Chemical composition and antimicrobial activity of Thymus pannonicus All. (Lamiaceae) essential oil

Abstract

This paper presents the results of a study on chemical composition and antimicrobial activity of Thymus pannonicus All. ( Lamiaceae) essential oil from Vojvodina province ( north of Serbia). The investigated oil was hydrodistilled from a flowering plant and analysed by GC and GC- MS. Fifty- three constituents were identified (> 97% of total oil), with geranial ( 41.42%, w/ w) and neral ( 29.61%, w/ w) as the most prominent. The antimicrobial activity of the oil was evaluated using agar disc diffusion and broth microdilution method against Staphylococcus aureus, Enterococcus faecalis, Pseudomonas aeruginosa, Escherichia coli, two strains of Klebsiella pneumoniae and two strains of Candida albicans. The essential oil exhibited antimicrobial activity to varying degrees against all tested strains. The maximum activity of T. pannonicus oil was observed against E. coli, S. aureus and both tested strains of C. albicans ( MIC = 50 mu l/ ml, each). Moderate activity was observed against P. aeruginosa and one of the tested strains of K. pneumoniae ( MIC = 200 mu l/ ml), while E. faecalis and the other strain of K. pneumoniae expressed a higher degree of resistance ( MIC > 200 mu l/ ml). This study confirms that essential oil of T. pannonicus possesses remarkable in vitro antimicrobial activity against several medicinally important pathogens. This is attributable to lemon- scented citral, a mixture of geranial and neral, which has well- documented antimicrobial activity against a range of bacteria and fungi.