Inhibitory Effect of an Extract of Sanguisorba officinalis L. on Ultraviolet-B-Induced Photodamage of Rat Skin

Abstract

We previously reported that chronic Ultraviolet-B (UVB) irradiation causes wrinkle formation, decreases skin elasticity, and damages/curls dermal elastic fibers. Those UVB-induced wrinkles can be improved by treatment with retinoic acid or with a CO₂ laser which results in a recovery of skin elasticity and a repair of elastic fiber linearity. We showed further that topical application of N-phenetyl-leucyl-tryptophane, an agent that specifically inhibits fibroblast-derived elastase, immediately after UVB irradiation inhibited UVB-induced wrinkle formation, maintained skin elasticity, and inhibited changes in the three-dimensional structure of dermal elastic fibers in a dose-dependent manner. In this study, the effects of an extract of Sanguisorba officinalis L., which also inhibits fibroblast-derived elastase, was evaluated for possible inhibition of UVB induced wrinkle formation, maintenance of skin elasticity, and prevention of damage to the 3-dimensional structure of dermal elastic fibers. Hind limb skins of 3-week-old Sprague-Dawley rats were irradiated with UVB at a suberythemal dose 3 times a week for 6 weeks. Simultaneously, an extract of Sanguisorba officinalis L. (at 0.2% (v/v) or 1% (v/v)) was topically applied 5 times per week immediately following each UVB irradiation and 1 d later. The extract of Sanguisorba officinalis L. inhibited wrinkle formation, maintained skin elasticity, and inhibited the decrease of dermal elastic fiber linearity in the rat hind limb skin in a dose-dependent manner. We have confirmed that the inhibition of elastase activity in fibroblasts immediately after UVB irradiation using an extract of Sanguisorba officinalis L. prevents chronic photodamage following UVB irradiation.