Selaginella Tamariscina extract reduces UVA-induced skin photodamage via regulating apoptosis and autophagy by AKT phosphorylation

Ultraviolet (UV) radiation, particularly in the UVA spectrum (320-400 nm), induces significant damage to both dermal and epidermal layers of skin, generating Reactive Oxygen Species (ROS) and triggering apoptotic pathways that compromise skin health. Selaginella tamariscina (P. Beauv.), a traditional medicinal plant widely used throughout Asia, contains numerous flavonoid compounds with recognized therapeutic value in Chinese medicine. Through comprehensive molecular analyses including Western blotting, RT-qPCR, and flow cytometry, we demonstrated that the Selaginella tamariscina (P. Beauv.) extract (STE) significantly reduces UVA-induced Apoptosis while simultaneously activating protective autophagic responses. Mechanistically, STE modulates Akt phosphorylation to regulate two critical downstream pathways: (1) the JNK-mediated apoptotic cascade and (2) the Akt/mTOR autophagic axis. In vivo experiments revealed that topical STE application provided substantial protection against UVA-induced photodamage in murine dorsal skin models. Liquid chromatography analysis identified amentoflavone as the principal bioactive component responsible for these protective properties. These findings collectively establish STE as a promising therapeutic agent against UVA photodamage, functioning through its dual capacity to attenuate Apoptosis while promoting cytoprotective Autophagy.