Targeted degradation of aberrant Tau for the discovery of Pulsatilla chinensis in Alzheimer's disease.

BACKGROUND: Alzheimer's disease (AD) is characterized by Tau aggregation, mitochondrial dysfunction, and oxidative stress, yet effective interventions targeting these pathological cascades remain limited. Therapeutic strategies that enhance autophagic and mitophagic clearance, attenuate Tau toxicity, and restore mitochondrial homeostasis are crucial for AD management. METHODS: This study investigated the neuroprotective effects of Pulsatilla chinensis extract (PCE) in SH-SY5Y neuronal cells and Caenorhabditis elegans (C. elegans) models of Tauopathy. Autophagic flux was evaluated by GFP-LC3 puncta formation, LC3-II conversion, and p62 degradation. Mitochondrial function was assessed through reactive oxygen species (ROS) production, mitochondrial membrane potential (MMP), and ultrastructural analysis. The roles of autophagy and mitophagy were examined using 3-methyladenine (3-MA) and the Parkin inhibitor AC220. In C. elegans, locomotion, Tau aggregation, oxidative stress, and mitophagosome formation were assessed, and pink-1 knockdown was used to confirm mitophagy dependence. RESULTS: PCE significantly enhanced autophagic flux, decreased total and phosphorylated Tau (p-Tau Ser404) levels, and improved neuronal viability. It significantly reduced ROS accumulation, maintained MMP, and preserved mitochondrial morphology under both Tau overexpression and H2O2-induced oxidative stress. Inhibition of autophagy or Parkin-mediated mitophagy negated these protective effects. In C. elegans, PCE ameliorated neuromuscular dysfunction, suppressed Tau inclusions, and reduced oxidative injury, while the loss of pink-1 abolished its benefits, underscoring the critical role of mitophagy. CONCLUSION: PCE exerts potent neuroprotective effects by promoting mitophagy, reducing Tau phosphorylation and aggregation, and restoring mitochondrial integrity. These findings reveal a novel mechanism linking mitochondrial quality control with Tau proteostasis and highlight PCE as a promising natural therapeutic candidate for AD.