In vitro Screening of Antibacterial and Antioxidant Activities of Essential Oils from Four Moroccan Medicinal Plants

Aims: Evaluation of antibacterial and antioxidant activities of essential oils extracted from Salvia officinalis, Mentha viridis, Eucalyptus globulus and Myrtus communis from Ouezzane province.

Study Design: In vitro evaluation of antibacterial and antioxidant activities of medicinal plants essential oils (EOs).

Place and Duration of Study: Department of Biology (Faculty of Sciences), July, 2015 to September, 2016 (15 Months).

Methodology: Essential oils were extracted by hydrodistillation method, while agar well diffusion, microdilution and spectrophotometry methods were used to evaluate the antibacterial and antioxidant activities respectively.

Results: The yields of EOs are 0.9, 1.2, 2.5, and 2.1% for M. communis, E. globulus, M. viridis, and S. officinalis respectively. EOs showed significant antibacterial activities against test bacterial strains:Staphylococcus aureus CECT 976, Staphylococcus aureus CECT 994, Listeria monocytogenes serovar 4b CECT 4032, Proteus mirabilis, Staphylococcus aureus MBLA, Escherichia coli K12, Pseudomonas aeruginosa and Bacillus subtilis 6633. Salvia officinalis EO was more active than the rest EOs on the test bacteria and exhibited the highest zone of inhibition (23 mm) against B. subtilis bacterial, while P. aeruginosa was the most resistant bacterial strain. S. officinalis and M. communis EO showed minimum inhibitory concentration at MIC=0.5 % (v/v) against L. monocytogenes and P. mirabilis. The antioxidant results indicated that M. communis and S. officinalis posess the ability to scavenge DPPH radicals. Their IC50 Values of 0.24 and 0.46 mg/mL respectively, suggest their anatioxidant capacity compared to reference drugs IC50value (IC50=0.027 mg/mL for ascorbic acid and IC50=0.043 mg/mL for Trolox).

Conclusion: Our study showed that apart from the local uses of the plants extracts, the EOs of S. officinalis,M. viridis, E. globulus and M. communis plants poses strong antibacterial and antioxidant properties and may be useful as food preservatives.