Novel Imidazole Phenoxyacetic Acids as Inhibitors of USP30 for Neuroprotection Implication via the Ubiquitin-Rho-110 Fluorometric Assay: Design, Synthesis, and In Silico and Biochemical Assays

USP30, a deubiquitinating enzyme family, forfeits the ubiquitination of E3 ligase and Parkin on the surface of mitochondria. Inhibition of USP30 results in mitophagy and cellular clearance. Herein, by understanding structural requirements, we discovered potential USP30 inhibitors from an imidazole series of ligands via a validated ubiquitin-rhodamine-110 fluorometric assay. A novel catalytic use of the Zn(l-proline)2 complex for the synthesis of tetrasubstituted imidazoles was identified. Among all compounds investigated, 3g and 3f inhibited USP30 at IC50 of 5.12 and 8.43 μM, respectively. The binding mode of compounds at the USP30 binding site was understood by a docking study and interactions with the key amino acids were identified. Compound 3g proved its neuroprotective efficacy by inhibiting apoptosis on SH-SY5Y neuroblastoma cells against dynorphin A (10 μM) treatment. Hence, the present study provides a new protocol to design and develop ligands against USP30, thereby offering a therapeutic strategy under conditions like kidney damage and neurodegenerative disorders including Parkinson's disease.