chemical composition of the essential oil from the leaves of marrubium vulgare l.from iran

background & aim: white horehound (marrubium vulgare l.) is a perennial medicinal plant of the family lamiaceae. the aim of this study was to identify of the chemical components of white horehound collected from isfahan.  experimental: the aerial parts of m. vulgare were collected from (kamu mountain) isfahan province central of iran, during 2014. the essential oils of samples were obtained by hydro-distillation, and analyzed using gas chromatography–mass spectrometry (gc–ms).  results & discussion: results of gc/ms indicated that 44 compounds were identified in the essential oil from the aerial parts of m. vulgare. the major constituents of the essential oil were β-caryophyllene (32.19%), (e)-β-farnesene(11.39%), 1,8-cineole (8.17%) and α-pinene (6.64%).a comparison of our results with different reports, differences in the volatile composition of the plants could be attributed to genetic (genus, species, and ecotype), chemotype, distinct environmental and climatic conditions, seasonal sampling periods, geographic origins, plant populations, vegetative plant phases, and extraction and quantification methods. industrial and practical recommendations: the biosynthesis of secondary metabolites, although controlled genetically, is strongly affected by the environmental influences of a particular growing region.