Lecithin Microemulsions with Gac Oil and Turmeric Essential Oil

It has been shown that water-in-oil microemulsions in lecithin–oleic acid–Vaseline oil–vegetable oil–essential oil–water systems can be obtained using the oil of a tropical plant, gac ( Momordica cochinchinensis ), and turmeric essential oil ( Curcuma longa ). Water (at least 6.5 wt %) can be incorporated into the microemulsions at a lecithin concentration in the organic phase of 20 wt %, a Vaseline oil-to-gac oil ratio of 1 : 1 (weight/weight), and an oleic acid-to-lecithin molar ratio of 0.2–0.8. Depending on the contents of water and lecithin, the hydrodynamic diameter of microemulsion droplets ranges from 3 to 21 nm. FTIR spectroscopy has been employed to show that, for the microemulsion with W = 14, the fraction of bulk (free) water in the droplets is 36.5 mol %, the fraction of hydration water (bound to polar groups of the surfactants) is 55.0 mol %, and the fraction of water trapped between hydrocarbon chains is 8.5 mol %. Using the dialysis method and a water-soluble dye Rhodamine C as a model, it has been shown that the rate of its transfer from the microemulsion to the physiological solution is 15.4 × 10 –3 g/(m 2 h). Approximately 3.2% of the dye has been found to be released over 6 h, thus making it possible to develop controlled drug release systems.