Formulation of a broad spectrum nanoemulsion from thymus vulgaris essential oil with enhanced antimicrobial activity against problematic gram negative bacteria and fungi

 Thymus vulgaris L. belonging to the Lamiaceae family has been widely used for medicinal purposes. T. vulgaris essential oil (EO), which is derived from the aerial parts of the plant, has shown potent antimicrobial activities in previous studies. However, its hydrophobic nature limits its application as a natural antimicrobial agent. Focusing on this problem, the objective of this survey was to develop a nano-sized delivery system of the EO not only to enhance the water solubility but also protect it from degradation.

 In this study, T. vulgaris EO-loaded nanoemulsion was prepared using Tween 80 and Span 60 (surfactants) via high-pressure homogenization and physicochemical characteristics, long-term stability and antimicrobial activity on a broad range of microorganisms were evaluated.

 The GC-MS of the EO showed that thymol was the primary compound with a 45.6% value. TEM and AFM images showed the spherical shape of nanoparticles with an average droplet size of 175.6 ± 0.96 nm. Interestingly, the final formulation had significantly lower MICs and MBCs in comparison with pure oil. Furthermore, it showed the lowest MIC and MBC values against Ent. faecalis and B. subtilis, respectively. Regarding the antifungal effects of the formulation, it was more effective on C. albicans than A. niger.

 The obtained data revealed that encapsulation of the EO as nanoemulsion significantly elaborates its antimicrobial properties, which can be considered as an stable and effective antimicrobial formulation for various purposes such as a food preservative.