Polyphenol-rich green propolis extract improves antioxidant and UV protection in sunscreen formulations

The potential adverse effects, including systemic reactions, of some organic filters used in sunscreens have driven the search for alternatives. Brazilian green propolis, rich in polyphenols, shows promise in absorbing ultraviolet (UV) radiation and acting as an antioxidant in photoprotective formulations, allowing for a reduction in the concentration of organic filters while maintaining photoprotection efficacy. Oil-in-water emulsions were prepared containing chemical UV filters-ethylhexyl methoxycinnamate and butyl methoxydibenzoylmethane-with or without the addition of Brazilian green propolis extract at concentrations of 2.5 % and 5.0 % (w/w), along with a blank formulation as control. These formulations were assessed for antioxidant activity, photoprotective efficacy (in vitro and in vivo methods), photostability, inhibition of lipid peroxidation in the stratum corneum of human volunteers, and skin permeability. The addition of green propolis extract significantly enhanced both the antioxidant activity and sun protection factor (SPF) of the formulations without significant penetration, making it an excellent alternative to partially replace organic filters. In vitro photoprotective efficacy parameters met broad-spectrum sunscreen standards, providing good to excellent ultraviolet A (UVA) protection. However, the low photostability of the formulations limited the extract's ability to protect the stratum corneum from lipid peroxidation. Therefore, Brazilian green propolis serves as a promising adjuvant in sunscreen formulation, boosting efficacy while ensuring formulation safety.