Nicotinonitrile-Based Dual Inhibitors of Tubulin and Topoisomerase II: Design, Synthesis, and Anticancer Evaluation

A series of 2,4,6-trisubstituted nicotinonitriles, compounds 10 – 41 , designed as pyridine-bridged analogs of combretastatin A-4 (CA-4), was synthesized to function as dual inhibitors of Topoisomerase II (Topo II) and tubulin polymerization. The anticancer potential of the synthesized compounds was evaluated against three cancer cell lines_MCF-7, HepG2, and HCT-116 using the LDH assay. Notably, several compounds 20, 26, 41, 38, 24, 27, 37, 23, 22, 33, 35, 19, 21 , respectively demonstrated superior cytotoxic activity against MCF-7 cells and compounds 20, 26, 38, 41, 39 , respectively showed moderate activity against HepG2 when compared to Doxorubicin, while maintaining good selectivity towards normal BJ-1 cells. Among these, compounds 26 , 20 , and 37 , respectively exhibited significant tubulin polymerization inhibitory activity ( 26 , 75% inhibition), ( 20 , 74.7% inhibition), ( 37 , 74.3% inhibition), compared to CA-4 (72.1% inhibition). Compound 37 showed strong inhibitory activity against Topo II (82.4% inhibition), while compound 20 showed moderate Topo II inhibitory activity (70.3% inhibition) compared with Doxorubicin (81.6% inhibition), highlighting the dual-target nature of these molecules. Cell cycle analysis further revealed that compounds 20 and 26 induced G2/M phase arrest in MCF-7 cells at rates of 43.30% and 50.69%, respectively, along with evidence of apoptosis induction. Molecular docking studies confirmed the favorable binding interactions of these compounds with both Tubulin and Topo II, aligning well with the in vitro findings. These findings underscore the potential of 2,4,6-trisubstituted nicotinonitriles as promising dual-target anticancer agents and pave the way for more potent derivatives with enhanced therapeutic efficacy.