Targeting autophagy via mitochondrial uncoupling: Discovery of novel serratin derivative as a potential therapeutic for Parkinson's disease.

Autophagy, a highly conserved cellular degradation pathway, plays a critical role in maintaining cellular homeostasis across eukaryotes. Dysregulation of autophagy has been implicated in numerous diseases, including neurodegenerative disorders such as Parkinson's disease. Although natural compounds like urolithin A and its synthetic analogue serratin (AN2) have been shown to induce autophagy, their limited potency and safety profiles necessitate the development of improved alternatives. In this study, a library of 27 novel AN2 analogues was synthesized and screened for autophagy-inducing activity. Among them, ORA471 emerged as a lead compound, exhibiting superior autophagy and mitophagy activation compared to AN2, along with reduced cytotoxicity in human fibroblast (VA-13) and neuroblastoma (SH-SY5Y) cell lines. Mechanistic investigations revealed that ORA471 induces autophagy primarily via the AMPK/ULK1 signaling pathway and acts as a mitochondrial uncoupler, dissipating membrane potential and enhancing respiration in isolated rat liver mitochondria. In vivo, ORA471 demonstrated low toxicity in Caenorhabditis elegans, zebrafish (Danio rerio), and mice (maximum tolerated dose: 300 mg/kg). Notably, it significantly improved motor function in a zebrafish model of MPTP-induced Parkinson's disease without eliciting adverse effects. These findings highlight ORA471 as a promising therapeutic candidate for the treatment of autophagy-related disorders, particularly Parkinson's disease.