Double emulsion solvent evaporation approach as a novel eugenol delivery system - Optimization by response surface methodology

Eugenol, a substance found in plant essential oils, exhibits significant health benefits due to its antioxidant, antibacterial, anti-inflammatory, anesthetic, and even anticancerogenic properties. Nevertheless, eugenol is light, heat and oxygen sensitive which limits its applications at an industrial scale and for practical uses. Considering these drawbacks, this study aimed to microencapsulate eugenol by double emulsion solvent evaporation technique. A response surface methodology was applied to obtain eugenol-loaded ethyl cellulose microparticles. Optimal encapsulation conditions were found considering a polymer concentration of 32.1 g/L and a surfactant concentration of 1.1% w/w. The microparticles obtained under the optimized encapsulation conditions provided the maximization of both eugenol encapsulation efficiency and the product yield to 94.7 +/- 1.0% and 82.0 +/- 11.2%, respectively. The obtained powder was characterized regarding wettability, thermogravimetric stability, thermal transitions, morphology and particle size distribution. In vitro release studies were performed using simulated gastrointestinal fluids. Microparticles obtained under optimized conditions showed to be spherical, presenting smooth but porous surfaces. The particle size distribution was narrow, and the mean particle size was 11.4 +/- 1.1 mu m. The release stimulation of eugenol in in vitro gastrointestinal transit revealed that this compound was favorably protected in the simulated salivary and gastric fluids. The highest release of eugenol was observed in the simulated intestinal fluid and was much higher than the minimum amount of eugenol that exhibits positive biological effects. This work demonstrates the promising possibility of incorporation of eugenol in ethyl cellulose polymer-based microparticles to potentiate added-value properties of functional foods and nutraceuticals.