Process optimization of curcumin loaded coconut oil and honey nanoemulsion for better skin permeation

Abstract

This study was focused on the optimization of preparing a curcumin-loaded coconut oil and honey nanoemulsion using a low energy emulsifying technique. Curcumin is a bioactive compound with low bioavailability and stability. Response surface methodology (RSM) with Box Behnken design was used to optimize the base formulation based on the three independent variables such as honey (1-3%), virgin coconut oil (1.0-1.5%) and Tween 80 (5.0-9.0%) to obtain low particle size (10.11nm), polydispersity index (0.27) and turbidity (0.24-1.11) system. Subsequently, the second optimization was carried out after curcumin was loaded into the base formulation. Another three independent variables such as polyethelene glycol (0.8-1.5%), curcumin (0.01-0.1%) and honey (1.8-2.4%) were used to produce the nanorange of particle size (14.32nm), narrow polydispersity index (0.152), and high encapsulation efficiency (98.0%). The curcumin-loaded nanoemulsion was found to have high stability with only 8.5% increment in particle size after storage for three months at 4°C and 45°C. The radical scavenging activity of encapsulated curcumin in nanoemulsion was decreased (<20%) compared to free curcumin. Nanoemulsion appeared to increase in vitro release rate of curcumin by about 42%, especially for the first 2h in Franz diffusion cell using rat skin.