HUP-55 is a prolyl endopeptidase inhibitor with an IC50 of 5 nM, shown to mitigate α-synuclein dimerization in Neuro2a cells, stimulate autophagy in HEK293 cells, and lower hydrogen peroxide-evoked reactive oxygen species (ROS) production in SH-SY5Y cells at a 10 µM concentration. Additionally, administration of HUP-55 at a dosage of 10 mg/kg reduces ipsilateral paw use and diminishes striatal oligomeric α-synuclein concentrations in a Parkinson’s disease mouse model, which is induced through adenoviral vector-mediated overexpression of α-synuclein (AAV-αSyn).