Prevention of the photodamage in the hairless mouse dorsal skin by kojic acid as an iron chelator

Kojic acid, a fungal metabolic product, has been used as a skin-depigmentin g agent in skin care products marketed in Japan. Iron in the skin is known to be involved in wrinkling as a result of chronic photodamage. Kojic acid was expected to have anti-wrinkling activity, since it possesses iron-chela ting activity. We now evaluated the anti-wrinkling activity of kojic acid b y using hairless mice exposed to chronic solar-simulating ultraviolet (UV) irradiation as model animal. At the end of a 20-week irradiation period, to pical application of kojic acid before UV irradiation was observed to drama tically prevent: (1) the wrinkling. (2) hyperplasia of the epidermis, (3) f ibrosis of the lower dermis, and (4) the increase of extracellular matrix c omponents in the upper dermis. These findings indicate that kojic acid is a typical agent preventing wrinkling of the skin due to chronic photodamage. (C) 2001 Elsevier Science B.V. All rights reserved.