Novel 6-aryl-1-(3,4,5-trimethoxyphenyl)-1 H -pyrazolo[3,4-d]pyrimidine derivatives: design, synthesis, and biological evaluation as potent tubulin polymerisation inhibitors with anticancer activity

Microtubules assembled from α/β-tubulin heterodimers are critical for cell division and well-established anticancer drug targets, making tubulin polymerization inhibitors a viable route for new chemotherapeutics. Guided by structural analysis of colchicine-site binders and tubulin-ligand computational simulations, we rationally designed and synthesized a series of 6-aryl-1-(3,4,5-trimethoxyphenyl)-1H-pyrazolo[3,4-d]pyrimidines as novel colchicine-binding site tubulin inhibitors. Derivative 9t displayed the strongest antiproliferative potency, with IC₅。 values of 0.065-0.096 μM across tested cancer lines. It exerted minimal toxicity to normal L929 fibroblasts, yielding a selectivity index over 300. Mechanistic assays confirmed 9t suppresses cell-free tubulin polymerization, destroys cellular microtubule architecture, induces persistent G₂/M cell cycle arrest, and activates cancer cell apoptosis. Overall, 9t serves as a promising dual-function tubulin inhibitor with both cytostatic and cytotoxic anticancer effects, meriting further preclinical investigation.