| Summary: | This study investigates the role of nobiletin (NBN), a dietary flavonoid preventing ultraviolet-A (UVA) radiation-induced oxidative damage and photoaging responses in skin epidermal keratinocytes (HaCaT). NBN treatment prevents cell toxicity, ROS, DNA damage, and apoptosis in UVA-exposed HaCaT cells. Furthermore, NBN prevents UVA radiation treatment-mediated overexpression of p-Erk-1, p-Jnk, p-p38, and AP-1 in HaCaT cells. Peroxiredoxin I (Prdx-1) is an antioxidant protein and enhanced activities of Prdx-1 have been considered a major target for inhibition of UVA radiation-mediated oxidative damage and photoaging responses. In this study, we noticed that NBN enhanced Prdx-1 expression, thereby enhancing antioxidants and inhibiting matrix metalloproteinase (MMP-1, MMP-2, MMP-9) and collagen degradation (Col-I and Col-III) in UVA-exposed HaCaT cells. Moreover, NBN treatment prevents UVA irradiation-induced downregulations of p-Smad and TGF-β1 expressions in HaCaT cells. In conclusion, our present results stated that NBN effectively prevents UVA-induced skin oxidative damage and photoaging responses through enhanced Prdx-1 expression.
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