Human beings are actively exposed to ultraviolet (UV) radiation, which is associated with skin cancer. This has encouraged the continuous search for more effective and safer photoprotective formulations. Along with the application of traditional organic sunscreens, there is a growing interest in “green products” containing natural compounds such as plant extracts and oils. This trend is combined with the use of nanotechnology as a tool for optimizing the vehicles of such compounds. Nanoemulsions (NEs) are suitable for the encapsulation of natural compounds, which improves topical treatment. Therefore, we have developed oil-in-water (O/W) nanoemulsions containing 3% buriti oil (BO), incorporated in a 10% vegetal extract of Aloe vera (AV) by means of ultrasonic processing to improve the chemical characteristics of this component and, consequently, its efficacy and safety in pharmaceutical and cosmetic formulations. The composition of the formulation was initially defined in a preliminary study on surfactants where the concentrations of Tween^® 80 and Span^® 20 were evaluated in relation to particle size and the polydispersity index (PDI). The nanoemulsion was prepared and then chemical sunscreens were incorporated with the aim of developing a sunscreen nanoemulsion called NE-A19. This nanoemulsion was found to be the best formulation due to its stability, droplet size (146.80 ± 2.74), and PDI (0.302 ± 0.088), with a monomodal size distribution. The stability was evaluated over 90 days and showed a low growth in particle size at the end of the study. NE-A19 exhibited good viscosity and organoleptic properties, in addition to an occlusion factor indicating an interesting and higher water holding capacity when compared with a NE without AV (p < 0.05). The in vitro efficacy and safety studies of NE-19A were promising. Its average in vitro sun protection factor value was 49, with a critical wavelength (λ_c) of 369.7 nm, satisfactory UVA protection, and a UVA/UVB ratio of 0.40, indicating broad spectrum protection against UVA and UVB radiation. Furthermore, NE-19A displayed a good safety profile in dermal keratinocytes. It can be concluded that NE-19A is a promising formulation for carrying natural products, such as buriti oil and AV, associated with synthetic filters in lower concentrations.

Viscum album L. (Santalaceae), also known as European mistletoe, is a semi-parasitic plant that grows on different host trees. Our group recently demonstrated the antitumoral activity of ethanolic V. album extracts in vitro, depending on the dose and the host tree, V. album ssp abietis from Abies alba being the most active extract. The goal of this work focused on the development of a new topical formulation containing V. album extracts, evaluation of in vitro toxicity and ex vivo skin permeation assays. The Poloxamer 407 hydrogel containing 5% of dry (VA_DEH) or aqueous (VA_AEH) extract presented dermal compatible pH and microbiological stability for 180 days. The hydrogels flow curve presented a non-linear relation, characteristic of non-Newtonian fluids, and the mean viscosity for the VA_DEH and VA_AEH was 372.5 ± 7.78 and 331.0 ± 2.83 Pa.s, respectively, being statistically different (Welch’s t test; p < 0.01). Additionally, WST-1 in vitro assays revealed a dose-dependent toxicity for both formulations and VA_DEH presented a higher activity than the VA_AEH. The promising cytotoxic potential of VA_DEH lead to the ex vivo skin permeation assay with 2.73 ± 0.19 µg/cm² of chlorogenic acid, which permeated at 8 h, showing a transdermal potential. These in vitro results support the idea that VA_DEH is a novel promising candidate for mistletoe therapy. Therefore, further in vivo and pre-clinical experiments should be performed to evaluate the safety and efficacy of this new dermic delivery system.