Synthesis and Biological Evaluation of Benzo[b]furans as Inhibitors of Tubulin Polymerization and Inducers of Apoptosis

A series of benzo[b]furans was synthesized with modification at the 5-position of the benzene ring by introducing C-linked substituents (aryl, alkenyl, alkynyl, etc.). These compounds were evaluated for their antiproliferative activities, inhibition of tubulin polymerization, and cell-cycle effects. Some compounds in this series displayed excellent activity in the nanomolar range against lung cancer (A549) and renal cell carcinoma (ACHN) cancer cell lines. (6-Methoxy-5-((4-methoxyphenyl)ethynyl)-3-methylbenzofuran-2-yl)(3,4,5-trimethoxyphenyl)methanone (26) and (E)-3-(6-methoxy-3-methyl-2-(1-(3,4,5-trimethoxyphenyl)vinyl)benzofuran-5-yl)prop-2-en-1-ol (36) showed significant activity in the A549 cell line, with IC50 values of 0.08 and 0.06M, respectively. G(2)/M cell-cycle arrest and subsequent apoptosis was observed in the A549 cell line after treatment with these compounds. The most active compound in this series, 36, also inhibited tubulin polymerization with a value similar to that of combretastatin A-4 (1.95 and 1.86M, respectively). Furthermore, detailed biological studies such as Hoechst33258 staining, DNA fragmentation and caspase-3 assays, and western blot analyses with the pro-apoptotic protein Bax and the anti-apoptotic protein Bcl-2 also suggested that these compounds induce cell death by apoptosis. Molecular docking studies indicated that compound 36 interacts and binds efficiently with the tubulin protein.