Formulation of nanoemulsion containing ellagic acid from pomegranate rind extract for skin delivery

Abstract

The objective of this study was to develop nanoemulsions containing ellagic acid extracted from pomegranate rind for the skin delivery. The two extraction methods were compared to select the suitable method between the hydrolysis and the hydrolysis followed by the recrystallization. The effect of the types and amounts of oils and surfactants including ellagic acid extract to the formation of nanoemulsions, which were prepared by low energy emulsification method, was studied. The physical stability of ellagic acid loaded nanoemulsion under accelerated conditions, including the centrifugation and the storage at 45 oC for 3 months, was investigated. The studies of release and permeation of ellagic acid-loaded nanoemulsion were carried out. This study found that the extraction method with the hydrolysis followed by the recrystallization was the suitable method because it gave the high purity of ellagic acid more than the hydrolysis only. Formulation which composed of rice bran oil could not form nanoemulsion, while sweet orange oil could form nanoemulsion easier than oleic acid. The different structures of surfactants formed nanoemulsion easier than the same structure. The optimal oil to surfactant ratios which could form nanoemulsions were not more than 2:1 depending on the types of surfactants. Moreover, ellagic acid loading did not affect the formation of nanoemulsion. The study of physical stability under the accelerated conditions found that all formulations were stable after centrifugation. In contrast, the stable formulation which was kept at 45 oC for 17 days was the formulation composed of sweet orange oil (10%) and Tween®20:Brij®97 (10%). This ellagic acid loaded nanoemulsion had a slow release profile compared to the solution, and ellagic acid did not permeated through new born pig skin. The developed nanoemulsions from this study would be of benefit for developing nanoemulsions containing other compounds that possess similar property of ellagic acid.