Rutina como fotoestabilizadora de protetores solares de amplo espectro / Routine as photostabilizer for broad spectrum sunscreens

The combination of butyl methoxydibenzoylmethane (BMBM) and octyl methoxycinnamate (EHMC) is widely used in pharmaceutical formulations but may exhibit alteration in spectral absorption following exposure to UV radiation. The addition of natural substances in sunscreen formulations has been explored regarding photoprotective efficacy. The main objective of this research was to evaluate the potential of rutin as a photostabilizer substance of EHMC and BMBM. The samples were evaluated before and after exposure to UV radiation to in vitro photoprotection and molecular interactions by 1H NMR, DSC, TG and qualitative analysis of the suppression of singlet energy state. The addition of rutin in the formulations containing BMBM and EHMC promoted an increase in the preservation of in vitro SPF of 53.9% to 65.8 (0.1% rutin ) and 70.8 % (1.0% rutin ). The DSC and TG curves of rutin showed interaction between the flavonoid and filters. The trans/cis ratio for EHMC improved from 5.5 ± 0.1 to 12.6 ± 0.4 with rutin addition. The suppression of the singlet state indicated that one of the mechanisms involved in the photostabilization is suppression of singlet excited state. These results can contribute to the development of broad-spectrum sunscreens formulations with increased safety and efficacy.