Synthesis and anticancer evaluation of novel azoloquinolinyl phosphonates, 1,4,2-Diazaphospholes, 1,4,2-Oxazaphosphinines, and 1,4,2-Diazaphosphinines containing a 4-quinolinone ring: Cytotoxicity, apoptosis, cell cycle analysis, In silico ADMET, and molecular docking studies

One-pot synthetic strategy was designed for the synthesis of novel diethyl (pyrazolo- [4,3-c]quinolin-3-yl)phosphonates and diethyl (isoxazolo[4,5-c]quinolin-3-yl)phosphonate. The novel phosphorus hetero­cycles of types 1,4,2-diazaphospholes, 1,4,2-oxazaphosphinines and 1,4,2-diazaphosphinines containing 4-quinolinone ring were also achieved. The designed strategies depended on a three component reaction of 4-oxo-1,4-dihydroquinoline-3-carboxaldehyde (1) with a series of bi-nucleophilic nitrogen reagents in the presence of diethyl phosphite under solvent-free and catalyst-free conditions. This newly developed approach helped to synthesize new ten organophosphorus compounds with good yields. The IR, MS and NMR spectroscopic tools were used to characterize the isolated compounds, and their formation mechanisms were discussed. All synthesized compounds were evaluated for their in vitro cytotoxicity against A549, MDA-MB-231 and HeLa cell lines. Compounds 10 and 11 exhibited the most potent cytotoxicity, in comparison with doxorubicin. Furthermore, these two compounds significantly induced early apoptosis and reducing cell viability in the studied tumor cells. Additionally, both compounds 10 and 11 demonstrated promising ability to arrest the cell cycle at the S and G2 phases. In silico ADMET predictions indicated that compounds 10 and 11 possess higher predicted human intestinal absorption (∼89.6% vs. 51.85% for doxorubicin), absence of AMES mutagenicity, and lower predicted acute and chronic oral toxicities in rats. Potential hepatotoxicity and CYP enzyme inhibition were also observed. Molecular docking against EGFR-T790M/V948R revealed that both compound 10 and 11 exhibited a binding affinity of −8.4 and 8.9 kcal/mol, respectively. The interactions of both compounds with key amino acid residues (e.g., LEU 718, VAL 726, ALA 743, MET 790, ASP 855) were consistent with their strong in vitro cytotoxic activity against A549 (EGFR-mutated) cells, supporting their potential as EGFR-targeted anticancer agents.