Topical isoflavones provide effective photoprotection to skin

• Published in: Photodermatology, photoimmunology & photomedicine photoimmunology & photomedicine, 2008-04, Vol.24 (2), p.61-66
• Main Authors: Lin, Jing-Yi, Tournas, Joshua A., Burch, James A., Monteiro-Riviere, Nancy A., Zielinski, Jan
• Format: Article
• Language: English
• Subjects: Administration, Cutaneous; Animals; antioxidants; Ascorbic Acid - administration & dosage; Ascorbic Acid - pharmacology; Ascorbic Acid - therapeutic use; Biological and medical sciences; Coumaric Acids - administration & dosage; Coumaric Acids - pharmacology; Coumaric Acids - therapeutic use; Dermatology; Dose-Response Relationship, Drug; Drug Combinations; Equol; Genistein - administration & dosage; Genistein - pharmacology; Genistein - therapeutic use; isoflavones; Isoflavones - administration & dosage; Isoflavones - pharmacology; Isoflavones - therapeutic use; Medical sciences; photoprotection; Phytotherapy; Plants, Medicinal; Skin - drug effects; Skin - radiation effects; Sunburn - pathology; Sunburn - prevention & control; Sunlight - adverse effects; Sunscreening Agents - administration & dosage; Sunscreening Agents - pharmacology; Sunscreening Agents - therapeutic use; Swine; Vitamin E - administration & dosage; Vitamin E - pharmacology; Vitamin E - therapeutic use
• ISSN: 0905-4383; 1600-0781
• DOI: 10.1111/j.1600-0781.2008.00329.x

Summary 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%α‐tocopherol, and 0.5% ferulic acid. Conclusion: Isoflavones provide effective photoprotection and are good candidate ingredients for protection against ultraviolet (UV) photodamage.