Nanoemulsion-based delivery systems to improve functionality of oregano essential oil: Molecular characterization and in vitro antifungal activity

Abstract

In this work, nanoemulsion-based delivery system was developedby encapsulation of oregano essential oil (OEO) at different con-centrations (0.5%, 0.75% and 1%, v/v) in poly-vinyl alcohol solution.The nanoemulsion systems (NES) were characterized in terms ofnanodroplet size distribution, zeta potential, thermal, molecular,micro-structural and antifungal properties. The average dropletdiameters were in the range of 70–75 nm while zeta potentialswere recorded in the range of 3.13 and 19.90 mV. Increase in theOEO concentration did not affect the size distribution of nanodropsin NES. Change in concentrations showed no visible differences inFTIR spectra; however, for the concentrations of 0.5, 0.75 and 1%,endothermic peak temperatures were recorded as approximately94, 105 and 117◦C, respectively. The antifungal activity of OEOin NES against mycelial growth ofAspergillus nigercould be sig-nificantly enhanced as compared to that of free OEO. The zonediameter of mycelial growth could be decreased by around 20%,55% and 65% over 6 days of incubation time for 0.5%, 0.75% and 1%,v/v concentrations, respectively. The results of this study show theincreased antifungal efficiency of the encapsulation of OEO in NESas compared to that of free OEO.