Protective effect of Juglans regia L., against ultraviolet-B induced photoaging in human epidermal keratinocytes

Solar ultraviolet-B radiation (UVB) has severe adverse effects on the structure and functions of the skin. Although, UVB (290-320 nm) represents only 5-10% of UV light reaching earth's surface, its contribution towards photoaging is tremendous. In this present study was investigate the photoprotective effect of methanolic extract of the male flower of J. regia L. (MEJR) against UVB induced photoaging in human epidermal keratinocytes (HaCaT). Cells were exposed to UVB-irradiation at a dose of 20 mJ/cm², induces the activation of several signaling pathways which are associated with oxidative stress and photoaging. A single dose of UVB irradiation increased the protein and mRNA expression of MAPKs, AP-1, MMPs, Smad7 and decreased expression of TIMP-1/2, TGF-β1, Smad3, procollagen type-1 in HaCaT cells. In contrast, pretreatment of MEJR (80 μg/ml) prior to UVB-irradiation significantly prevented the overexpression of MAPKs, AP-1, MMPs, Smad7 and decreased expression of TIMP-1/2, TGF-β1, Smad3 and procollagen type-1 in HaCaT cells. Moreover, pretreatment of MEJR (80 μg/ml) prior to UVB-irradiation significantly prevents apoptosis in sub G_o-phase. Thus, MEJR protects UVB-mediated photoaging in human skin cells, by modulating the expression of photoaging markers. The protection might be because of the presence of the good amount of bioactive compounds in MEJR.