Influence of Ferulic Acid on SPF and pH Values in Semi-Solid Formulations

Abstract

Background: There is a need for exploring plant-derived materials to be used as UV filters in sunscreens [1]. Research highlights the photoprotective potential of phenolic acids [2], along with their influence on modifying the pH of the formulation in which they are incorporated [3]. Thus, it is beneficial to investigate ferulic acid, a phenolic acid, to unveil its photoprotective and pH-modifying properties in semi-solid formulations. Aim(s): The aim of this study was to develop semi-solid cream formulations containing 1% and 2% ferulic acid, evaluate their SPF and pH, and compare the results with a control formulation lacking ferulic acid. Methods: Three formulations were prepared, each consisting of a lipophilic phase (pumpkin seed oil, Olivem-1000) and a hydrophilic phase (water, glycerol, phenoxyethanol). One served as a control, while the others contained 1 % or 2 % of dispersed ferulic acid. Sun Protection Factor (SPF) was determined using the Mansur method through in vitro UV spectroscopy. pH was measured potentiometrically with a pH-meter (WinLab, Windaus Labortechnik, Germany). The results were analyzed using “MS Excel 2023”. Results: The SPF values obtained for the formulations were 2.189 ± 0.109 (control cream), 3.857 ± 0.193 (cream with 1% of ferulic acid), and 6.883 ± 0.344 (cream with 2% of ferulic acid). Values differ statistically significantly (p < 0.001). Results indicate that the incorporation of ferulic acid into semisolid formulation may enhance its photoprotective properties. The pH values measured were 6.673 ± 0.334 (control cream), 5.575 ± 0.279 (cream with 1% of ferulic acid), and 4.518 ± 0.226 (cream with 2% of ferulic acid). Values differ statistically significantly (p < 0.001). These results suggest that higher ferulic acid concentrations may lower pH to undesirable levels, requiring pH-modifying agents in semi-solid formulations. Conclusion: Ferulic acid enhanced SPF of the formulation, indicating its potential as a photoprotective agent, but also statistically significantly lowered pH, requiring careful formulation adjustments to ensure optimal skin compatibility.