Preparation, characterization, and biological evaluation of retinyl palmitate and Dead Sea water loaded nanoemulsions toward topical treatment of skin diseases

Millions of people suffer from different types of skin diseases worldwide. In the last decade, the development of nanocarriers has been the focus of the pharmaceutical and cosmetic industries to enhance the performance of their products, and to meet consumers' demands. Several delivery systems have been developed to improve the efficiency and minimize possible side effects. In this study, retinyl palmitate and Dead Sea water loaded nanoemulsions were developed as carriers to treat skin conditions such as photoaging, psoriasis, or atopic dermatitis. Toxicity profiles were carried out by means of viability, cell membrane asymmetry study, evaluation of oxidative stress induction (reactive oxygen species), and inflammation via cytokines production with a human keratinocyte cell line (HaCaT) and a mouse embryo fibroblasts cell line (BALB/3T3). Results showed that loaded nanoemulsions were found to be non-cytotoxic under the conditions of the study. Furthermore, no oxidative stress induction was observed. Likewise, an efficacy test of these loaded nanoemulsions was also tested on human skin organ cultures, before and after ultraviolet B light treatment. Viability and caspase-3 production assessment, in response to the exposure of skin explants to the loaded nanoemulsions, indicated non-toxic effects on human skin in culture, both with and without ultraviolet B irradiation. Further the ability of loaded nanoemulsions to protect the skin against ultraviolet B damage was assessed on skin explants reducing significantly the apoptotic activation after ultraviolet B irradiation. Our promising results indicate that the developed loaded nanoemulsions may represent a topical drug delivery system to be used as an alternative treatment for recurrent skin diseases.