Acacetin resists UVA photoaging by mediating the SIRT3/ROS/MAPKs pathway.

Ultraviolet A (UVA) radiation is a major contributor to the pathogenesis of skin photoaging, and the aim of this study was to investigate the effect of Acacetin on skin photoaging in UVA-irradiated mice and human dermal fibroblasts (HDF). Healthy dorsal depilated rats were irradiated with UVA 30 J/cm daily, every other day, for 1 month. Acacetin (40, 80 mg kg/day) was coated to the bare skin of the rats' backs 1 h before UVA irradiation. HDF were treated different concentrations of Acacetin (5, 10, 20 μg/ml) and then irradiated with UVA (20 J/cm ). Acacetin was found to be effective in ameliorating UVA-induced oxidative stress and cell death. Acacetin also prevented the UVA-induced decrease of SIRT3, reduced the activation of mitogen-activated protein kinases (MAPKs, p-38 and p-JNK) and blocked the down-regulated activation of oxidative stress in matrix metalloproteinases (MMPs). In addition, Acacetin increased the expressions of collagen-promoting proteins (TGF-β and Smad3). Finally, the SIRT3 inhibitor 3-TYP blocked all protective effects of Acacetin, indicating that the protective effect of Acacetin against UVA photoaging is SIRT3-dependent. Acacetin effectively mitigated photoaging by targeting the promotion of SIRT3, inhibiting the UVA-induced increases in MMPs and pro-inflammatory factors, and promoting TGF-β and Smad3.