|The potential anti-aging properties of a hydroglycolic preparation (HP) from Epilobium angustifolium were assessed by determining its ability to reduce the stress induced senescence of dermal fibroblasts (NHDF) in vitro and to protect skin against harmful UV in vivo. The chemical profile of HP was determined by using LC-DAD-MS. Treatment of NHDF by HP at 10 ug/ml increased the cell viability of senescent (serum-free cultivated cells) NHDF. This preparation diminished the connective tissue growth factor and fibronectin gene expression in senescent NHDF. It also elevated collagen release in repeatedly UV-irradiated NHDF and down-regulated the induced release of both matrix metalloproteinases (MMPs) -1 and -3, and tissue inhibitor of MMP -1 and -2. In addition, a downregulating effect of HP on gene expression of hyaluronidase 2 in repeatedly UV-irradiated NHDF was observed. The in vivo experiments showed that the application of HP before single UV-exposure protected skin against UVinduced erythema formation. Major constituents of HP were preliminarily identified as gallic acid, oenothein B, chlorogenic acid, myricetin-3-O-hexoside, myricetin-3-O-rhamnoside, quercetin-7-O-glucuronide and kaempferol- 3-O-hexoside. The observed reduction in connective tissue growth factor, fibronectin and tissue inhibitor of MMPs indicates the antifibrotic and anti-scarring potential of HP. It is suggested that this phytopreparation protects dermal cells and extracellular matrix components against cutaneous aging and exhibits a significant photoprotective effect. Polyphenols, the major constituents of HP, may account for the observed benefits. HP from Epilobium angustifolium could be a potential candidate to be used as an active ingredient in dermatological and cosmetic formulations.