Chemical Composition and Evaluation of Antimicrobial Activity of the Origanum majorana Essential Oil Extracted by Microwave-assisted Extraction, Conventional Hydro-distillation and Steam distillation

This work aims to highlight the effect of the extraction methods used on the chemical composition and evaluation of antimicrobial activity of the Origanum majorana Essential oil. Accordingly, three different extraction methods namely; Microwave-assisted extraction (MWE), hydro-distillation (HD) and steam distillation (SD) were used for O. majorana essential oils (EOs) extraction. There is variability in the chemical composition of essential oils obtained from the different extraction methods used. Overall, HD showed the highest % of oxygenated monoterpenes (66.8 %), while SD showed the highest % of monoterpene hydrocarbons (46.85 %). Oxygenated sesquiterpenes showed the lowest percentage of the EOs (3.6 % HD, 1.4 % MWE and 0.7 % SD). Terpinene-4-ol was the major components of O. majorana EO with different percentages 28.49 % HD, 22.28 % MWE and 26.72 % SD. EOs was tested for their antimicrobial activity against ten pathogenic microbes (fungi, yeast and bacteria). EOs extracted by SD method showed antimicrobial activities against all tested pathogens with variation degree. This result could be useful in designing the best extraction method. Key word: Microwave-assisted extraction, hydro-distillation, steam distillation, essential oil, antimicrobial activities and Origanum majorana.