Chemical composition and in vitro antimicrobial activity of the essential oil of Origanum minutiflorum O!Schwarz & PH!Davis

The essential oil obtained by hydrodistillation from the aerial parts of Origanum minutiflorum 0 Schwarz & PH Davis, an endemic species in Turkey, was analysed for its antimicrobial activity in vitro. Gas chromatography/mass spectrometry analysis of the essential oil resulted in the identification of 34 constituents accounting for 961.5 mL L-1 of the oil, the major compounds present being carvacrol (793.4 mL L-1), p-cymene (32.6 mL L-1) and gamma-terpinene (21.4 mL L-1). The in vitro antimicrobial activity of the essential oil was investigated in order to evaluate its efficacy against 16 bacteria and two yeasts, using disc diffusion and minimum inhibitory concentration methods. The essential oil showed strong antimicrobial activity against all test micro-organisms except Pseudomonas aeruginosa. Its main components carvacrol and p-cymene were also assayed for their antimicrobial activities. Carvacrol exhibited comparable activity to the crude oil, proving it to be the main component responsible for the biological activity observed. This study demonstrates the in vitro antimicrobial activity of the essential oil of this endemic remedy against a wide spectrum of clinically important microorganisms, including pathogenic yeasts, being the first report on the anticandidal properties of the essential oil of O. minutiflorum. (c) 2006 Society of Chemical Industry