Synthesis and Biological Evaluation of Novel 2-Aroyl Benzofuran-Based Hydroxamic Acids as Antimicrotubule Agents

Abstract

Because of synergism between tubulin and HDAC inhibitors, we used the pharmacophore fusion strategy to generate potential tubulin–HDAC dual inhibitors. Drug design was based on the introduction of a N-hydroxyacrylamide or a N-hydroxypropiolamide at the 5-position of the 2-aroylbenzo[b]furan skeleton, to produce compounds 6a–i and 11a–h, respectively. Among the synthesized compounds, derivatives 6a, 6c, 6e, 6g, 11a, and 11c showed excellent antiproliferative activity, with IC50 values at single- or double-digit nanomolar levels, against the A549, HT-29, and MCF-7 cells resistant towards the control compound combretastatin A-4 (CA-4). Compounds 11a and 6g were also 10-fold more active than CA-4 against the Hela cell line. When comparing the inhibition of tubulin polymerization versus the HDAC6 inhibitory activity, we found that 6a–g, 6i, 11a, 11c, and 11e, although very potent as inhibitors of tubulin assembly, did not have significant inhibitory activity against HDAC6.