Design, synthesis and bioevaluation of 2,7-diaryl-pyrazolo[1,5-a]pyrimidines as tubulin polymerization inhibitors

Two series of 2,7-diaryl-pyrazolo[1,5-a]pyrimidines as tubulin polymerization inhibitors were designed to restrict bioactive configuration of (E,Z)-vinylogous CA-4. All of the target compounds were synthesized and then evaluated for their in vitro antiproliferative activities against three cancer cell lines (MCF-7, SGC-7901 and A549). Among them, 6d exhibited the most potent antiproliferative activity against the MCF-7 with IC₅₀ value of 0.047 μM. Moreover, 6d significantly inhibited tubulin polymerization, disrupted microtubule networks, arrested cell cycle at G2/M phase, induced apoptosis and hindered cancer cell migration. Colchicine competition assay and molecular docking studies suggested that 6d could interact with tubulin by binding to the colchicine site.