Nicotinonitrile based dual inhibitors of tubulin and topoisomerase II exhibit potent anticancer activity

A series of 2,4,6-trisubstituted nicotinonitriles, compounds 10-41, was designed as pyridine bridged analogs of combretastatin A4 and evaluated as dual inhibitors of topoisomerase II and tubulin polymerization. Anticancer activity was tested in MCF7, HepG2, and HCT116 cells using the LDH assay. Several compounds including 19-24, 26-27, 33-35, 37-38, and 41 showed strong cytotoxicity in MCF7 cells, while compounds 20, 26, 38, 39, and 41 displayed moderate activity in HepG2 cells with good selectivity toward BJ1 normal cells. Tubulin polymerization assays identified compounds 20, 26, and 37 as the most active, showing inhibition values of 74.7%, 75.0%, and 74.3%, compared with 72.1% for combretastatin A4. Compound 37 showed strong topoisomerase II inhibition (82.4%), while compound 20 displayed moderate inhibition (70.3%), both compared with DOX (81.6%). Cell cycle analysis indicated that compounds 20 and 26 induced G2 and M phase arrest in MCF7 cells and promoted apoptosis. Molecular docking confirmed favorable binding interactions with both tubulin and topoisomerase II. These results highlight 2,4,6-trisubstituted nicotinonitriles as promising dual target anticancer candidates and support their further optimization.