Preparation of Microemulsion of Cymbopogon citratus (DC) Stapf Essential Oil and Analysis of Antioxidant Activity

Abstract:

This study aimed to prepare a microemulsion system that could improve the application of Cymbopogon citratus (DC) Stapf essential oil in aqueous environments. The essential oil was extracted by hydrodistillation and the volatile compounds in the extract (CEO) were analyzed by GC-MS. Pseudo-ternary phase diagrams were constructed to select suitable ingredients for preparation of microemulsions. The effects of surfactants, co-surfactant, Km value, pH value, ionic strength and other factors on the microemulsion existing area in the pseudo ternary diagram were investigated, to prepare a C.EO O/W microemulsion using Tween 80 (surfactant), anhydrous ethanol (co-surfactant), and deionized water ( aqueous phase). Its physicochemical properties were as follows: pH 6.73 ± 0.02, viscosity 15.50 ± 0.11 mPa ? s-1, conductivity 108.90 ± 0.21 μs ? cm-1, and average particle diameter 16.50 ± 0.53 nm. Finally, the antioxidant activities of CEO and CEO microemulsion were determined by DPPH, ORAC and PSC assays. The obtained results showed the antioxidant activity of CEO microemulsion was significantly higher than that of CEO (p < 0.05).