Synthesis, docking study, and structure-activity relationship of novel niflumic acid derivatives acting as anticancer agents by inhibiting VEGFR or EGFR tyrosine kinase activities

A new series of niflumic acid (NF) derivatives were synthesized by esterification of (NF) to give ester compound 1, which was treated with hydrazine hydrate to produce (NF) hydrazide 2. Hydrazine-1-carboxamide compounds (3A–C), and hydrazine-1-carbothioamide derivatives (4A–D) were synthesized by treatment of (NF) hydrazide with phenyl isocyanate, and phenyl isothiocyanate derivatives, respectively. The cyclization of (4B–D) and (3B) was achieved using NaOH solution to produce 1,2,4-triazole derivatives (5A–C) and 6, respectively. The prepared compounds were characterized using IR, ¹HNMR, ¹³CNMR, and MS (ESI) spectroscopy. A molecular docking study was performed to evaluate the binding affinity of the synthesized compounds against EGFR and VEGFR kinase domains which revealed that compounds 3B, and 4A had the best binding energy (-7.87, and -7.33 kcal/mol, respectively) against VEGFR, while compound 5A had the best binding energy (-7.95 kcal/mol) against EGFR. The biological investigation results indicated that all the tested compounds caused cell killing in the two cancer cell lines (Hep G2 and A549) studied, with compound 4C being the most cytotoxic, as well as being cancer selective. Additionally, compound 4C-treated Hep G2 cells were arrested at the S and G2/M cell cycle phases. Cytotoxicity of compound 4C was attributed to apoptosis as determined by flow cytometry and qRT-PCR results of the apoptosis markers p53, BAX, and caspase-3. Finally, compound 4C inhibited VEGFR kinase activity, while compound 5B inhibited EGFR kinase activity. In conclusion, the novel (NF) derivatives are potent anticancer agents, inhibiting cell proliferation by inhibiting EGFR and VEGFR tyrosine kinase enzymes.