Rational Construction of a Lipid Droplet-Targeted Redox-Responsive Ratiometric Probe for Screening of Antioxidant Drugs and Its Application in Parkinson’s Disease

Parkinson's disease (PD) is a neurodegenerative disorder that is increasingly prevalent due to global aging, requiring urgent efforts to uncover its pathogenic mechanisms and develop effective treatments. Abnormal lipid metabolism in glial cells is a key pathological feature of PD, and identifying lipid droplets (LDs) is crucial for studying lipid metabolism, disease progression, and potential therapies. Ferroptosis, a regulated form of cell death induced by iron-dependent lipid peroxides, is a critical mechanism in PD. Ferroptosis is closely linked to PD progression and redox homeostasis, regulated by reactive oxygen and sulfur species. Understanding changes in redox homeostasis in LDs during ferroptosis in the brain is key to understanding PD pathology. However, the development of fast-responding and highly sensitive reversible fluorescent probes for monitoring of LDs redox changes during ferroptosis and PD is still lacking. To address this, we developed <b>RHG-Se-5F</b>, a reversible, ratiometric, LDs-targeted fluorescent probe that detects fluctuations in HClO/GSH levels. <b>RHG-Se-5F</b> visualized HClO elevation and GSH depletion in LDs during ferroptosis. We also established a high-throughput screening platform and identified Salidroside (Sal) as a potent ferroptosis inhibitor. Sal promotes GSH synthesis, scavenges ROS, and activates the Nrf2/GPX4 pathway, protecting neurons from ferroptosis. <b>RHG-Se-5F</b> can image HClO/GSH levels in brain tissue, showing increased HClO levels in PD mouse brains as PD progresses, validating its potential in PD pathology. In conclusion, <b>RHG-Se-5F</b> is a valuable molecular tool for in situ fluorescence labeling of redox levels in biological samples, with broad potential for neurobiological research and the diagnosis and monitoring of neurological diseases.