Design, microwave-assisted domino synthesis, and biological evaluation of novel naphtho[2,3-b]furan-4,9-diones as rigidified combretastatin A-4 analogs inducing G0/G1 cell cycle arrest and apoptosis.

A novel series of fourteen fluorinated naphtho[2,3-b]furan-4,9-dione derivatives (5a-n) was designed, synthesized, and structurally mapped as conformational equivalents of the microtubule-disrupting agent combretastatin A-4 (CA-4). The core medicinal chemistry strategy relied on replacing the highly flexible exo-ethylene linker of native CA-4 with a rigid carbonyl lock at the C-2 position of the furan ring, thereby restricting rotatable bonds and freezing the peripheral aromatic rings into a stable cis-like bioactive orientation. One aryl domain was substituted with an electron-deficient naphthoquinone core to maximize target pocket engagement. These target compounds were efficiently synthesized in good yields (69-81%) via a microwave-assisted three-component reaction utilizing 2-hydroxy-1,4-naphthoquinone, fluorinated aromatic aldehydes, pyridinium bromides, and 1,4-diazabicyclo[2.2.2]octane as a base catalyst. Cytotoxicity screening demonstrated that this structural rigidification maintained antiproliferative profiles across human cancer cells (KB, HepG2, A549, and MCF7), with compound 5c emerging as the most potent compound exhibiting IC50 values ranging from 1.90 to 11.48 µM. Flow cytometric analysis showed that compound 5c induced concentration-dependent cell cycle arest at G0/G1 phase and apoptosis in A549 cells. Molecular docking and density functional theory simulations predicted that 5c establishes a highly stable interaction network within the colchicine binding site of the α,β tubulin interface. Collectively, these findings highlight compound 5c as a highly promising preliminary cytotoxic lead for the development of novel anticancer agents.