Design, synthesis, and biological evaluation of novel amidoxime or amidine analogues of some 4-anilino-6,7-dimethoxyquinazolines with a potent EGFR inhibitory effect

A series of 6,7-dimethoxy-4-anilinoquinazoline derivatives, which have amidine (4a-4d, 5a-5c, 6a-6d) and amidoxime (4e, 5d, 6e) moieties, were synthesized and evaluated their anticancer activity on various cancerous cell lines (H1975, HCC827, and H23). Among the synthesized compounds, 4c was found to be the most potent inhibitor of EGFR, comparable to erlotinib, with higher than 10 μM EC50 values for H1975 and H23 and 0.16 μM EC50 value for HCC827 cells. 4c activated mitochondrial apoptosis signaling and suppresses EGFR downstream signaling, such as ERK1/2 and PI3K/Akt pathways in HCC827 NSCLC cells (EGFR Del19) as erlotinib. Molecular docking and molecular dynamics simulations studies were performed to evaluate the interaction and binding energies of all synthesized compounds against EGFR wild type, EGFR T790M/L858R, EGFR L858R, and EGFR exon-19 deletion mutant (del-747-749). 4c showed a similar binding profile with erlotinib as stable binding interaction values. Also, 4c formed additional hydrogen bonds via the amidine group in its structure, potentially increasing its affinity and stability within the binding pocket. Hence, 4c was selected as a lead compound for further pharmacomodulation.