Methodology to Reach Full Spectral Photo-Protection by Selecting the Best Combination of Physical Filters and Antioxidants

Antioxidants help prevent the generation of free radicals in the skin's deeper layers, where traditional sunscreen filters may no longer be effective. Here, a generic strategy for selecting optimal mixtures of antioxidants and physical filters is provided. The radical production of selected common physical filters after UV irradiation, the capacity of various antioxidants, and the interaction between these compounds were investigated in solution by optical measurement of DPPH scavenging, allowing a theoretical calculation of the amount of antioxidant required to scavenge UV-induced radicals. In addition, the antioxidant capacity and scattering characteristics of the sample were examined. The addition of physical filters resulted in a decrease in the high radical protection factor (RPF) of cream formulations that did not contain physical filters at first. In varied degrees, the inclusion of physical filters to formulations containing antioxidants reduces their reduction capability, as demonstrated by the results.