Discovery of Propionic Acid Derivatives with a 5‑THIQ Core as Potent and Orally Bioavailable Keap1–Nrf2 Protein–Protein Interaction Inhibitors for Acute Kidney Injury

Keap1 plays a crucial role in regulating the Nrf2-mediated
cytoprotective
response and is increasingly targeted for oxidative stress-related
diseases. Using small molecules to disrupt the Keap1–Nrf2 protein–protein
interaction (PPI) has emerged as a new strategy for developing Nrf2
activators. Through extensive structure–activity relationship
studies, we identified compound 56, which features a
unique 5-tetrahydroisoquinoline scaffold and acts as a potent inhibitor
of the Keap1–Nrf2 PPI. Compound 56 exhibited significant
inhibitory activity (IC50 = 16.0 nM) and tight Keap1 binding
affinity (Kd = 3.07 nM), along with acceptable
oral bioavailability (F = 20%). Notably, 56 enhanced antioxidant defenses in HK-2 renal tubular epithelial cells
and significantly reduced plasma creatinine and blood urea nitrogen
levels in acute kidney injury (AKI) mice. These findings collectively
position compound 56 as a promising candidate for the
treatment of AKI.