This study aimed to investigate the mechanism underlying the protective effects of galangin against HO/UVB-induced damage usingandmodels of photodamage. Moreover, we identified the involvement of miRNA regulation in this process. The HO/UVB-treated HS68 human dermal fibroblasts and UVB-induced C57BL/6J nude mice were used asandmodels of photodamage. The results showed that galangin treatment alleviated HO/UVB-induced reduction in cell viability, TGFβ/Smad signaling impairment, and dermal aging. Based on the results of microRNA array analyses and database searches, hsa-miR-4535 was identified as a potential candidate miRNA that targets Smad4., galangin treatment activated Smad2/3/4 complex and inhibited hsa-miR-4535 expression in H2O2/UVB-exposed cells., topical application of low (12 mg/kg) and high doses (24 mg/kg) of galangin to the dorsal skin of C57BL/6J nude mice significantly alleviated UVB-induced skin photodamage by promoting TGFβ/Smad collagen synthesis signaling, reducing epidermal hyperplasia, wrinkle formation, and skin senescence, as well as inhibiting hsa-miR-4535 expression. Taken together, our findings indicate a link between hsa-miR-4535 and TGFβ/Smad collagen synthesis signaling and suggest these factors to be involved in the photo-protective mechanism of galangin in dermal fibroblasts against HO/UVB-induced aging. The evidence indicated that galangin with anti-aging properties can be considered as a supplement in skin care products. 2 2 2 2 2 2 2 2in vitro in vivo in vitro in vivo In vitro In vivo
