Effect of New Coumarin‐Ferulate Cyclic Conjugates on Acute Kidney Injury (Oxalate Nephropathy): Synthesis, In Vitro and In Vivo Evaluations

The inflammatory cascade of acute kidney injury (AKI) is mainly mediated by TLR-4/NF-κB signaling pathway that ultimately leads to increased release of proinflammatory cytokines. This study aims to discover novel anti-inflammatory candidates targeting proinflammatory cytokines in AKI. Ten novel coumarin-ferulate cyclic conjugates (1-10) are synthesized (by oxidative coupling of coumarin derivatives and ethyl ferulate) and characterized (mass and nuclear magnetic resonance spectroscopy). All compounds are tested for cytotoxicity and proinflammatory cytokines inhibition properties using RAW 264.7 cells stimulated with lipopolysaccharide (Enzyme Linked Immuno-Sorbent Assay). The compounds 3 and 5 show excellent inhibition of TNF-α, IL-6, and IL-1β secretions and also inhibite IL-1β protein levels (western blot). Compounds 3 and 5 are then evaluated (50 mg kg^-1 oral dose; C57BL/6 mice) in an oxalate-induced nephropathy model. Results show significant renal protection in compound-treated animals, as evidenced by a significant decrease in the blood urea nitrogen and creatinine, IL-1β protein expression (western blot), and mRNA levels of TNF-α and IL-1β (real-time polymerase chain reaction)). A decrease in the overall percentage of live immune cells and kidney resident macrophages in renal tissues is also observed (flow cytometry). Additionally, histopathological studies (H&E staining) show a significant decrease in renal tissue damage (tubular injury index). This findings suggest that these new anti-inflammatory conjugates have a strong renal protective effect.