Cynarin Alleviates Sodium Iodate-Induced Retinal Pigment Epithelium Injury by Regulating Oxidative Stress and Inflammation

Background: Age-related macular degeneration (AMD) is a leading cause of irreversible vision loss and is strongly driven by oxidative stress and inflammation. This study investigated the protective effects of cynarin against sodium iodate (NaIO3)-induced retinal pigment epithelium (RPE) injury, focusing on the MAPK and NF-κB signaling pathways. Materials and Methods: Human ARPE-19 cells were exposed to NaIO3, and cell viability was assessed by the MTT assay. Protein expression of MAPK components (p38, JNK, ERK) and the NF-κB pathway was analyzed by Western blotting, and pro-inflammatory cytokine (IL-1β, IL-6, TNF-α) mRNA expression was measured by RT-qPCR. In vivo, NaIO3-induced retinal degeneration in C57BL/6 mice was treated with cynarin (3 or 10 mg/kg) for seven days, and retinal changes were evaluated by fundus photography, fluorescein angiography, and OCT. Results: Cynarin preserved ARPE-19 cell viability without cytotoxicity. It significantly attenuated NaIO3-induced p38 and JNK phosphorylation, IκB degradation, and NF-κB activation while downregulating IL-1β, IL-6, and TNF-α expression. In vivo, cynarin reduced drusen-like lesions, hyperfluorescent abnormalities, and retinal thinning, and dose-dependently suppressed ocular pro-inflammatory cytokines. Conclusions: Cynarin protects against oxidative stress-induced retinal degeneration by suppressing MAPK and NF-κB inflammatory signaling, representing a promising therapeutic candidate for preventing or delaying NaIO3-induced dry AMD-like retinal injury.