Artemia salina Leach in photoprotection: A new model to evaluate the potential of nanoparticles for topical application

Using animals in research has generated heated debates around the world and in the scientific community. This fact, as well as the need to prove the safety and efficacy of pharmaceutical products, has led to a growing interest in the search for alternative methods. Given this scenario, developing new alternative methods has become vital, also including an economic perspective. Invertebrate models can be easily applied in research assays owing to their advantages, such as effortless handling, low cost, small size, and simple anatomy. Therefore, this study aimed to evaluate the use of the invertebrate microcrustacean Artemia salina Leach for phototoxicity and photoprotection assays. As a product model, solid lipid nanoparticles of the flavonoid rutin (SLNR) were produced, which shows several activities, focusing on antioxidant action. SLNR were obtained by the hot melt microemulsion technique using a high-shear homogenizer. These were characterized and evaluated for the average particle size (185 +/- 12.19 nm), polydispersity index (0.140 +/- 0.11), zeta potential (-34.04 +/- 1.43 mV), and encapsulation efficiency (98.82 +/- 0.37 %), representing satisfactory values for topical applications. Regarding the physicochemical characterization by thermal analysis, infrared spectroscopy by Fourier transform and X-ray diffraction results showed a decrease in the crystallinity of rutin. In the assay with Artemia salina, the lethal doses were determined against UVA radiation (LD50 = 133.2 +/- 0.82 J/cm2) and UVB (LD50 = 0.45 +/- 0.056 J/cm2). In the phototoxicity assay, the SLNR showed photochemopreventive action, mainly against UVA radiation. In photoprotection studies, formulations containing SLNR exhibited greater photoprotection against UVB radiation (86.60 % +/- 7.64 viability) than UVA (58.00 % +/- 10.95 viability). In conclusion, the method using Artemia salina L. proved to be a very effective and promising tool to evaluate the phototoxic and photoprotective potential of nanostructured systems.