New alternatives in photoprotection: Preparation and evaluation of lamellar silicate derivatives and their use as sunscreens

The objective of this work is to investigate different sunscreens and Viscogel group organoclays for the preparation of new intercalated sunscreens to improve the effectiveness and safety in photoprotection using new approach methodology (NAMs). For this study, we examined Diethylamino hydroxybenzoyl hexyl benzoate (DHHB), octyl methoxycinnamate (OMC), Bemotrizinol (BEMT) and Viscogel S4®, S7®, and B8® using a set of Saccharomyces cerevisiae mutant strains that are sensitive to UVA, UVB and Solar Simulated Light (SSL) to evaluate their photoprotective and mutagenic potential. Additionally, we developed delaminated nanocomposites by chemical intercalation reactions followed by ultrasonic treatment to enhance clay exfoliation. These nanocomposites were then characterized using X-ray Powder Diffraction (XRPD), Differential Scanning Calorimetry (DSC), Thermogravimetric Analysis (TGA) and Dynamic Light Scattering (DLS). As a function of photoprotective action and safety, the combination of Viscogel S4® and OMC filter was chosen for nanocomposite development. Our results evidenced the intercalation of the OMC in the organoclay (S4 + OMC-NC). Survival and mutagenesis tests indicated a positive effect of the formulation, as it increased cell survival to SSL, even without reducing mutagenesis, while its respective physical mixture was unable to provide antimutagenic protection. S4 + OMC-NC showed promising results for photoprotection, offering cellular protection combined with antimutagenic effects upon SSL exposure. This formulation enables prospects for the preparation of new, effective and safe photoprotective formulations.