Influence of antioxidants on the photostabilization of avobenzone (UVA filter) and octyl p-methoxycinnamate (UVB filter) on photoprotectors

Abstract

In order to promote broad-spectrum protection, most sunscreens are associated with at least two organic filters (UVA and UVB). The combination of avobenzone (BMBM), UVA filter, and octyl methoxycinnamate (EHMC), UVB filter, is well known and widely used in industrial formulations and pharmaceutical compounding, but shows alteration in spectral absorption after UV radiation exposure. The most commonly used strategy to reduce the instability of the combination is based on the addition of photostabilizer agents. The addition of natural substances in sunscreen formulations has been explored, especially the group of flavonoids, which someones shows positive results regarding photoprotective efficacy. The main objective of this research was to evaluate the potential of antioxidants as a photostabilizer substance of EHMC and BMBM. Formulations will be develop containing the two filters associated or not with antioxidants with best performace results preliminaries and according to factorial design at three levels. The formulations will be evaluated for in vitro photoprotective efficacy applied on PMMA plates and analyzed by spectrophotometer with integrating sphere reflectance before and after exposure to UV radiation. Molecular interactions of filters with antioxidants will be evaluated by 1H NMR, DSC, TG and qualitative analysis of the suppression of singlet energy state, evaluation of cutaneous permeation in vitro (cell Franz difusion), EPR ex vivo and FRET. This work represents news perspectives to the development of broad-spectrum sunscreens formulations with increased safety and efficacy. (AU)