Sauchinone attenuates UVB-induced photoaging by suppressing oxidative stress and ferroptosis through activation of the Keap1-Nrf2 pathway in dermal fibroblasts.

Skin photoaging induced by chronic ultraviolet B (UVB) exposure is primarily driven by oxidative stress. Emerging evidence suggests that ferroptosis contributes to UVB-induced skin damage. Sauchinone, a phenolic lignan derived from Saururus chinensis, possesses potent antioxidant and anti-inflammatory properties; however, its protective effects and underlying mechanisms against UVB-induced skin damage remain unclear. This study aimed to investigate the potential photoprotective effects and underlying mechanisms of sauchinone against UVB-induced skin damage in dermal fibroblasts. UVB-induced HFFs were used as an in vitro model of photoaging. Cellular senescence, extracellular matrix (ECM) degradation, oxidative stress, and ferroptosis were evaluated using fluorescence staining, flow cytometry, qPCR, ELISA, and western blot analysis. Sauchinone significantly attenuated cellular senescence and ECM degradation in UVB-induced HFFs, as evidenced by reduced SA-β-gal activity and decreased expression of p16 and p21, increased COL1A1 levels, and decreased MMP1 levels. Sauchinone also alleviated oxidative stress by reducing intracellular ROS and MDA levels while restoring GSH content and antioxidant enzyme activity. In addition, sauchinone attenuated ferroptosis-related features, including reduced lipid ROS and Fe2+ accumulation, and normalized ACSL4, GPX4, FTH1, and SLC7A11 expression. Mechanistically, sauchinone was associated with activation of the Keap1-Nrf2 pathway, as evidenced by decreased Keap1 levels, enhanced nuclear translocation of Nrf2, and upregulation of downstream antioxidant genes. Importantly, pharmacological inhibition of Nrf2 using ML385 partially reversed the protective effects of sauchinone on oxidative stress, ferroptosis, cellular senescence, and ECM degradation. Our findings revealed that sauchinone protected fibroblasts against UVB-induced photoaging by inhibiting oxidative stress and ferroptosis, potentially through activation of the Keap1-Nrf2 pathway.