A topical antioxidant solution containing vitamins C and E stabilized by ferulic acid provides protection for human skin against damage caused by ultraviolet irradiation.

BACKGROUND: Skin cancer and photoaging changes result from ultraviolet (UV)-induced oxidative stress. Topical antioxidants may protect skin from these effects. OBJECTIVE: We sought to determine whether a stable topical formulation of 15% L-ascorbic acid, 1% alpha-tocopherol, and 0.5% ferulic acid (CEFer) could protect human skin in vivo from substantial amounts of solar-simulated UV radiation. METHODS: CEFer and its vehicle were applied to separate patches of normal-appearing human skin for 4 days. Each patch was irradiated with solar-simulated UV, 2 to 10 minimal erythema doses, at 2-minimal erythema dose intervals. One day later, skin was evaluated for erythema and sunburn cells, and immunohistochemically for thymine dimers and p53. UV-induced cytokine formation, including interleukin (IL)-1alpha, IL-6, IL-8, and IL-10, and tumor necrosis factor-alpha, were evaluated by real-time polymerase chain reaction. RESULTS: CEFer provided significant and meaningful photoprotection for skin by all methods of evaluation. LIMITATIONS: The number of patients evaluated was relatively small. CONCLUSION: CEFer provided substantial UV photoprotection for skin. It is particularly effective for reducing thymine dimer mutations known to be associated with skin cancer. Its mechanism of action is different from sunscreens and would be expected to supplement the sun protection provided by sunscreens.

Topical isoflavones provide effective photoprotection to skin.

BACKGROUND/PURPOSE: Isoflavones, one main group of phytoestrogens, have antioxidative and photoprotective effects in cellular and mouse studies. The aim of this study is to obtain a more comprehensive understanding of the isoflavone-mediated photoprotection with the pig skin model, a more human-resembling model. METHODS: The pig skin was treated with five well-known isoflavone compounds (genistein, equol, daidzein, biochanin A, and formononetin) and one antioxidant combination solution of 15% vitamin C and 1% vitamin E and 0.5% ferulic acid (CEF) daily for 4 days. Skin was irradiated with solar-simulated UV irradiation, 1 to 5 minimal erythema dose (MED) at 1-MED intervals. Evaluation was carried out 24 h later by colorimeter-measured erythema and sunburn cell numbers. RESULTS: Topical application of 0.5% solutions of three individual phytoestrogens - genistein, daidzein, biochanin A - are better than similar solutions of equol or formononetin in protecting pig skin from solar-simulated ultraviolet (SSUV)-induced photodamage, as measured by sunburn cell formation and/or erythema. However, the protection was less than that provided by a topical combination antioxidant standard containing 15% L-ascorbic acid, 1%alpha-tocopherol, and 0.5% ferulic acid. CONCLUSION: Isoflavones provide effective photoprotection and are good candidate ingredients for protection against ultraviolet (UV) photodamage.