Antifungal Activity of Nanoemulsion of Iranian Tarragon (Artemisia dracunculus L.) Essential Oil

Abstract

Background: Despite the considerable activity of herbal Essential Oils (EOs) as safe food preservatives, problems such as high volatility, low water solubility, and low stability in adverse environmental conditions restrict their use in food products. This work aimed to investigate in vitro antifungal activity of oil-in-water nanoemulsion of Iranian Artemisia dracunculus L. (tarragon) EO. Methods: Nanoemulsion of tarragon EO was formed by ultrasound method through blending 10 wt% of tarragon EO, 85 wt% water, and the mixture of 5 wt% surfactants (Tween® 80/Span® 80). The droplet size and zeta potential were measured. The antifungal activity was evaluated against four different fungi, Aspergillus niger, Penicillium spp., Fusarium spp., and Saccharomyces cerevisiae through determining Minimum Inhibitory Concentration (MIC), Minimum Fungicidal Concentration (MFC), and mycelial growth test. Data were statistically analyzed by the software of SPSS 22.0. Results: Main fragments of tarragon EO found to be beta-cis-ocimene, estragole, and beta-trans-ocimene. Nanodroplets had a zeta potential of -30 mV and an average diameter of 50 nm. For A. niger, Penicillium spp., Fusarium spp., and S. cerevisiae, the MIC and MFC values of nanoemulsion were identical and obtained at 1.50, 2.05, 1.61, and 1.14 µg/ml, respectively, while these values of free EO were higher and as follows: 2.81, 4.52, 3.75, and 2.40 µg/ml, respectively. Mycelial growth showed that encapsulated EO had the most fungitoxic potential against A. niger (inhibition 41%) and S. cerevisiae (inhibition 68%). Also, Penicillium spp. was the most resistant against both EO and nanoemulsion. Conclusion: The growth inhibitory activity of tarragon was significantly enhanced when encapsulated as nanoemulsion.