The combination of vitamin C and vitamin E with ferulic acid is based on a well-documented complementarity among these three antioxidants. Vitamin C, being water-soluble, primarily acts in the aqueous phase of tissues, while vitamin E, being lipid-soluble, protects lipid structures from oxidation, especially cell membranes. Ferulic acid, in turn, plays a stabilizing and synergistic role: it enhances the efficacy of both vitamins while limiting their degradation, particularly that of vitamin C, which is known for its instability in aqueous solution. Combining these three compounds allows achieving a broader antioxidant coverage and a more stable formulation, for example to prevent photoaging.
A study in vivo particularly interesting was conducted to assess the photoprotective efficacy of a complex combining 15% L-ascorbic acid (vitamin C), 1% alpha-tocopherol (vitamin E), and 0.5% ferulic acid, referred to as CEFer in the study. After topical application of this formulation or the vehicle to human skin sites for four days, the researchers exposed these areas to UV radiation simulating sunlight, at doses ranging from 2 to 10 times the MED. As a reminder, the MED is the minimal erythema dose, that is, the minimal UV dose causing sunburn.
The results showed significant protection against UV-induced damage, in contrast to the vehicle control. CEFer markedly reduced both erythema and the occurrence of so-called “sunburn” cells, decreasing from 31.5 ± 14.3 with the vehicle to 8.4 ± 7 with CEFer. “Sunburn” cells are UV-damaged keratinocytes that undergo apoptosis to prevent the transmission of DNA mutations. Cytokine analysis also revealed a decrease in the expression of proinflammatory mediators such as interleukins IL-1α, IL-6, IL-8, IL-10, and TNF-α. This study illustrates the strong synergy among the three antioxidants—ferulic acid, vitamin C, and vitamin E—enabling not only formulation stabilization but also the delivery of multifactorial protection against UV-induced oxidative stress.