Abstract

Antimicrobial effects of various hexane extract and fatty acids have been extensively studied. Fatty acids with nonpolar compounds have been found to have a broad spectrum of microbicidal activity. The hexane extracts from leaf and stem of Origanum vulgare L. ssp. Viride which were collected from Northwestern Iran, were obtained by Soxhlet apparatus. The fatty acids in hexane extracts were derived to their methyl esters and determined by gas chromatography/flame ionization detector (GC/FID) and gas chromatography/mass spectrometry (GC/MS) systems. The extracts from the leaf and stem were characterized by a high amount of unsaturated fatty acids (UFA) and long-chain hydrocarbons. The main components of the leaf and stem extracts were tridecane (14.6 and 16.1%), 9, 12, 15-octadecatrienoic acid (ω-3) (14.7 and 1.2%), tetradecane (8.7 and 10.2%), hexadecanoic acid (1.6 and 6.7%) and pentadecane (5.7 and 4.1%), respectively. The hexane extract from O. vulgare leaf was detected as an important source of unsaturated fatty acid compounds. The hexane extract from stem of O. vulgare consisted mainly of aliphatic compounds; while in leaf extract of the plant, unsaturated fatty acids predominated over aliphatic components. The antimicrobial activity of the extracts of those samples were determined against seven Gram-positive and Gram-negative bacteria (Bacillus subtilis, Enterococcus faecalis, Staphylococcus aureus, Staphylococcus epidermidis, Escherichia coli, Pseudomonas aeruginosa and Klebsiella pneumoniae), as well as three fungi (Candida albicans, Saccharomyces cerevisiae and Aspergillus niger). The bioassay showed that the both oils exhibited a moderate antimicrobial activity.

Key words: Origanum vulgare ssp. viride, Lamiaceae, antimicrobial activity, unsaturated fatty acid, ω- 6.