Exploring the In Vitro Photoprotective Effect of a Combination of Aspalathus linearis Natural Extracts: First Steps in Developing New Technologies for Photoprotection Strategies

There is a need for new technologies in photoprotection. The negative effects of solar exposure on the skin have been amply demonstrated and there is an urgency for the development of alternative photoprotective approaches. In this respect, natural extracts represent the most interesting and promising source. Among them, <i>Aspalathus linearis</i> extracts appear to be an excellent candidate due to supporting evidence, their multiple beneficial biological effects, and their robust toxicological profile. Here, we first explored the photoprotective properties of two different <i>Aspalathus linearis</i> extracts (fermented and unfermented) individually, and then in combination, in a simplified model assessing Normal Human Dermal Fibroblast survival after UVB radiation. Surprisingly, we found the fermented extract to be more photoprotective than the unfermented one. In addition, a specific combination of the two extracts showed a synergistic effect. By HPLC and FRAP analyses, we observed that the photoprotective effect did not correlate with the amount of <i>Aspalathus linearis</i> main characteristic metabolites nor with the antioxidant capacity of the ingredients. Finally, an additional photoprotective effect was observed when <i>Aspalathus linearis</i> extracts were combined with a <i>Polypodium leucotomos</i> extract (Fernblock^®), a well-known botanical ingredient with demonstrated photoprotection activities. Thus, this work provides a solid scientific basis for the inclusion of this technology in future topical and systemic photoprotective strategies.