Chemical Composition and Antimicrobial Activity of Essential Oil and Various Extracts of Onosma sieheana Hayek Roots

Abstract

:The present study reports the chemical composition and antimicrobial activity of Onosma sieheana roots. Essential oil (EO) and extracts were isolated from the roots of Onosma sieheana by hydrodistillation and Soxhlet extraction, respectively. Essential oil and methanol extract were further analyzed by using the Gas chromatography-Mass spectrometry (GC/MS) technique. The extraction yields were 6.50, 0.35, and 1.70 with methanol, petroleum ether, ethyl acetate, respectively, and 0.07% for essential oil. Exactly sixty-one compounds were identified in essential oil and twenty-three compounds were identified in methanol extract. The main component of the essential oil was p-cymene (27.32%), whereas the main component of the methanol extract was methyl palmitoleate (15.19%). Although, the essential oil extracted from the roots of Onosma sieheana by the hydrodistillation method, was characterized by a high level of sesquiterpenes, the one extracted from Onosma sieheana roots by the Soxhlet extraction method was characterized by a high level of monoterpenes. Subsequently, these extracts were investigated for their antibacterial activity against two Gram- positive and two Gram-negative strains as well as for their antifungal activity against two yeast strains. As a result of antimicrobial studies, it has been determined that essential oil of Onosma sieheana roots have more effective antifungal activity than antibacterial activity. The antimicrobial effects of the extracts were found to be similar.