Chemical Composition, Antioxidant and Antimicrobial Activities of the Essential Oil of <i>Origanum majorana</i> Growing in Middle Atlas of Morocco

Abstract

The purpose of this work was to determine the chemical composition and assess the antibacterial and antioxidant  activity of the essential oil of Origanum majorana grown in the Middle Atlas of Morocco. The yield of essential oil  extracted by hydro-distillation is about 1 ± 0.05%.The chemical composition of the essential oil extracted from the Aerial  parts of Origanum majorana was studied by gas chromatography coupled with mass spectrometry (GC/MS). The results  of the GC-MS analysis of the volatile components of the EO revealed the presence of 21 components, representing  98.51% of the total essential oils (EOs). The main compounds were carvacrol (41.09%), terpinen-4-ol (28.08%), followed  by p- Cis-Sabinene hydrate (21.12%), γ-Terpinene (2.7%), Spathulenol (1.5%) and thymol (1.32%). Antioxidant activity was  determined by the DPPH and FRAP assays. The results demonstrated that our EOs exhibit a significant antiradical effect  with an IC₅₀ value of 0.25 mg/mL compared to the pure reference antioxidant BHT with an IC₅₀ value of 0.11 mg/mL.  The antibacterial effect of this essential oil was tested against five bacterial strains. Staphylococcus aureus was the most  sensitive with a MIC value of 1.98 ± 0.01, followed by Klebsiella pneumonia with an MIC value of 2.01 ± 0.35ug/ml. The  results show that Origanum majorana essential oil process antibacterial and antioxidant properties and it can be used  as a natural food preservative and as an antimicrobial agent for the treatment of several infectious diseases caused by  bacteria.