Chemical Composition of Essential Oil and Antibacterial Activity ofDracocephalum subcapitatum

Dracocephalum subcapitatum, a wild local herb from the North East of Khorasan Province of Iran, was investigated for its essential oil chemical constituents and antibacterial activity. The essential oil was obtained by hydrodistillation of dried aerial parts of plant in 1.5 % (w/w) yield. The analysis of oil indicated the presence of 25 components that was 98.4 % of the essential oil constituents. The main components were geranial (63.4 %), limonene (23.4 %), p-Menth-l-en-9-ol (4.4 %) and caryophyllene E (4.3 %), respectively. The oil, together with the crude methanol extract of rhizomes was assayed for antibacterial activity against two strains of Gram-positive and two strains of Gram-negative bacteria by the disc diffusion assay. Results indicates that essential oil was more effective than its crude methanolic extract, as the essential oil exhibited potent activity against S. aureus and E. coli and moderate activity against B. subtilis and P. aeruginosa, but the microbes were not high sensitive against the crude extract.