Photoprotective nanoemulsions containing microbial carotenoids and buriti oil: efficacy and safety study

Abstract Photoprotective nanoemulsions are able to attenuate skin damage from overexposure to the sun, thus avoiding the immediate effects caused by ultraviolet radiation. The global cosmetics market understands that there is a demand and greater acceptance by consumers for formulations containing natural products compatible with the skin. Consequently, there is an increasingly need to develop such products that are safe and effective. Furthermore, there is a growing interest in nanoemulsions (NE) in the pharmaceutical industry, due the versatility of incorporating lipophilic substances into cosmetic formulations. In the present work, oil-in-water photoprotective nanoemulsions containing microbial carotenoids, buriti oil and chemical filters were developed and characterized. The essential physical properties of the droplets, the transmission electronic microscopy (TEM), the sun protection factor (SPF) as well as the stability of the formulations were determined. In vitro phototoxicity was evaluated using Balb 3T3 with relative cell viability estimated by Neutral Red Uptake, with the Photo Irritation Factor (PIF) and the Medium Photo Effect Factor (MPF) as the measurement parameters. Nanoemulsion 3 (NE3) showed spherical morphology with an average droplet size of 142.11 ± 0.92 nm and polydispersity index (PDI) of 0.198 ± 0.017. This nanoemulsion containing microbial carotenoids and buriti oil exhibited a SPF of 36 ± 1.5. Neutral Red Uptake revealed that the cells kept their viability even after irradiation and those nanoemulsions containing the microbial carotenoids and buriti oil were not phototoxic. The addition of microbial carotenoids and buriti oil in nanoemulsions was positive in increasing the mean SPF values compared to the control formulation.