KDR and neoplasm: To further investigate theirmechanism of action, VEGFR-2 enzyme inhibition assays were conducted,as VEGFR-2 plays a crucial role in angiogenesis and tumor progression.Compound 5h exhibited potent VEGFR-2 inhibition (IC50 = 0.049 ± 0.002 μM), comparable to the referencedrug sorafenib (IC50 = 0.037 ± 0.001 μM), whilecompounds 5j (IC50 = 0.098 ± 0.011 μM)and 5c (IC50 = 0.915 ± 0.027 μM)also showed notable inhibitory effects.