Topical isoflavones provide effective photoprotection to skin.
OBJECTIVE
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.


CONCLUSIONS
Isoflavones provide effective photoprotection and are good candidate ingredients for protection against ultraviolet (UV) photodamage.
Lin
Jing-Yi
JY
Chang Gung Memorial Hospital, Chang Gung University College of Medicine, Taipei, Taiwan. lindajylin@adm.cgmh.org.tw
Tournas
Joshua A
JA
Burch
James A
JA
Monteiro-Riviere
Nancy A
NA
Zielinski
Jan
J
D000279:Administration, Cutaneous; D000818:Animals; D001205:Ascorbic Acid / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D003373:Coumaric Acids / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D004305:Dose-Response Relationship, Drug; D004338:Drug Combinations; D060754:Equol; D019833:Genistein / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use; D007529:Isoflavones / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D008517:Phytotherapy; D010946:Plants, Medicinal; D012867:Skin / Q000187:drug effects* / Q000528:radiation effects; D013471:Sunburn / Q000473:pathology / Q000517:prevention & control*; D013472:Sunlight / Q000009:adverse effects; D013473:Sunscreening Agents / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D013552:Swine; D014810:Vitamin E / Q000008:administration & dosage / Q000494:pharmacology / Q000627:therapeutic use
C007610:4',7-dihydroxy-3,4-dihydroisoflavone; D003373:Coumaric Acids; D004338:Drug Combinations; D007529:Isoflavones; D013473:Sunscreening Agents; D014810:Vitamin E; C007768:formononetin; D060754:Equol; C004742:daidzein; C004999:ferulic acid; D019833:Genistein; D001205:Ascorbic Acid; C004541:biochanin A