Okanin Attenuates Mitochondrial Dysfunction and Apoptosis in UVA-Induced HaCaT Cells by Mitophagy Through SIRT3 Pathway

As the primary bioactive flavonoid in Coreopsis tinctoria, okanin has emerged as a promising antioxidant compound of substantial pharmacological interest. However, its efficacy against UVA-mediated photoaging remains unexplored. This research investigated the molecular mechanism underlying the photoprotective activity of okanin against UVA-mediated photoaging. Network pharmacology was employed to predict the pharmacological mechanism of Coreopsis tinctoria in skin photoaging, which was then validated through in vivo and in vitro studies. In vitro experiments indicated that treatment with okanin alleviated oxidative damage, apoptosis and mitochondrial dysfunction in HaCaT cells exposed to UVA radiation. In addition, the interaction between okanin and SIRT3 was confirmed using molecular docking, SPR and DARTS assays. However, silencing SIRT3 with siRNA abolished the promoting effects of okanin on mitophagy genes, confirming that okanin protects HaCaT cells against UVA damage through SIRT3 regulation. In in vivo, okanin enhanced the expression of SIRT3 and FOXO3a in dorsal skin, mitigating UV-mediated skin damage. Taken together, our results suggest the protective effects of okanin against UV radiation in both HaCaT cells and mice induced, at least in part, by regulating SIRT3/FOXO3a/PINK1/Parkin signaling pathway. These findings highlight the potential of okanin for use in skin care products aimed at promoting skin repair following UVA exposure.