Improvement of the antimicrobial activity of Thymus capitatus essential oil by nanoencapsulation
Mariem BenJemaa1, Fatma Zohra Rahali1, Hanen Falleh1,*, Latifa Abdennebi-Najar2,3, Riadh Ksouri1

1 Laboratory of Aromatic and Medicinal Plants, Biotechnology Center of Borj-Cédria BP 901 2050 Hammam-Lif, Tunisia
2 Quality and Health Department, IDELE Institute, 149 rue de Bercy, 75595 Paris CEDEX 12, France
3 Centre de Recherche Saint-Antoine (CRSA), Sorbonne University, INSERM UMR_S_938, 75020 Paris, France

* Email:; Phone : +216 79 41 28 48

Problem and context: Essential oils from aromatic and medicinal plants such as thyme often possess considerable antimicrobial activities. However, these essential oils are unstable, volatile, and easily oxidized, which lead to a loss in their efficiency.

Objective: The aim of this study is to improve the antimicrobial activity of thyme essential oil by stabilizing it in nanoemulsions.

Methods: A response-surface experimental design was used to optimize the process of nanoemulsion of Thymus capitatus essential oils. The effect of the encapsulation on the essential oil antimicrobial activity was evaluated using antibacterial activity tests of the crude oil and the optimal nanoemulsion against four bacterial strains (two Gram-negative, two Gram-positive) and a yeast (Candida albicans).

Results and discussion: The optimal nanoemulsion had a droplet size of 380 nm, a polydispersity index below 0.5 and was stable during the 15 days storage period. The stabilization process significantly improved the T. capitatus crude oil antimicrobial activity. The crude essential oil exhibited a moderate antimicrobial activity against Salmonella typhimurium and Staphylococcus aureus with growth inhibition percentages between 3 and 17%, respectively. The growth inhibition percentages of all selected strains by the oil encapsulated in a nanoemulsion-based delivery system were significantly higher than that of crude oil. The growth percentages increased from 6 to 53% for P. aeruginosa, 17 to 54% for S. aureus, 4.6 to 63% for E. faecalis, 3 to 52% for S. typhimurium, and 6.7 to 69% for the yeast Candida albicans.

Conclusion: The antimicrobial activity results revealed that encapsulating the T. capitatus essential oil in nanoemulsion delivery system is very advantageous.