Development of N-hydroxybenzamide derivatives with indole-containing cap group as histone deacetylases inhibitors

Histone deacetylases inhibitors (HDACIs) have captured more and more attention in many diseases therapies, of which cancer is the most intractable. A novel series of N-hydroxybenzamide derivatives containing indole cap group was designed and synthesized. Most compounds exhibited excellent HDACs inhibitory activity, especially 8q-8v with low nanomolar IC₅₀ values (1.5-13.0 nM), which were much more potent than the positive control SAHA. The most potent compound 8r showed slightly higher growth inhibitory activity than SAHA in multiple tumor cell lines, even though, antiproliferative activity of 8r seemed inferior to its HDAC inhibition activity. Poor transcellular permeability obtained from the result of HDAC class I cellular assay could explain the inferior antiproliferative activity. In addition, 8r displayed similar HDAC IIa cellular activity to class I, which indicated 8r might be a potent pan-HDAC inhibitor.