Synthesis, antitumor evaluation, and in silico investigation of pyridine-based pyrimidotriazine and triazolopyrimidine derivatives as potential EGFR-targeted anticancer agents

Abstract

Cancer remains a major global health challenge and one of the leading causes of mortality worldwide. In the present study, a new series of fused nitrogen-containing heterocyclic derivatives was synthesized from a pyridine-based pyrimidinethione key synthon. Hydrazinolysis followed by cyclo-condensation and condensation reactions afforded structurally diverse pyrimidotriazine, triazolopyrimidine, hydrazone, and pyrazolopyrazole derivatives. The antiproliferative activities of the synthesized compounds were evaluated against human lung carcinoma (A549) and human prostate carcinoma (PC3) cell lines, with WI-38 normal human lung fibroblasts used to assess selectivity. Compounds 6 and 8 emerged as the most promising cell-based candidates, displaying the highest activities against A549 and PC3 cells, respectively, together with favorable selectivity toward cancer cells relative to WI-38 normal cells. To investigate a possible mechanism underlying the observed antiproliferative effects, the most active derivatives (6–8) were screened for EGFR kinase inhibition. Compound 7 exhibited the strongest inhibitory activity, surpassing sorafenib and revealing a clear structure–activity relationship within the series. To gain structural insight into target recognition, molecular docking studies were conducted against EGFR (PDB ID: 1M17) and cyclin-dependent kinase 2 (CDK2; PDB ID: 2A4L). The docking protocol was validated by re-docking of the corresponding co-crystallized ligands, demonstrating satisfactory reproduction of the experimental binding modes. Compounds 6–8 adopted favorable binding orientations within the ATP-binding pockets of both enzymes. Compound 7 displayed the most favorable EGFR binding profile, whereas compound 6 showed the strongest predicted affinity toward CDK2. The observed interactions emphasized the importance of molecular planarity, aromaticity, hydrogen-bonding capability, and hydrophobic contacts in stabilizing ligand–enzyme complexes. In silico ADME analysis revealed generally acceptable drug-likeness and pharmacokinetic characteristics, with compound-dependent variations in lipophilicity, gastrointestinal absorption, blood–brain barrier permeability, and P-glycoprotein recognition. Collectively, these findings identify compounds 6–8 as promising anticancer candidates, with compounds 6 and 8 representing potent and selective cell-based leads and compound 7 emerging as a promising EGFR-directed scaffold for further optimization. Furthermore, this work expands the chemical space of fused nitrogen heterocycles and provides a useful platform for the development of kinase-targeted anticancer agents.