Identification of mercaptoacetamide-based HDAC6 inhibitors via a lean inhibitor strategy : screening, synthesis, and biological evaluation

Non-selective inhibition of different histone deacetylase enzymes by hydroxamic acid-based drugs causes severe side effects when used as a (long-term) cancer treatment. In this work, we searched for a potent zinc-binding group able to replace the contested hydroxamic acid by employing a lean inhibitor strategy. This instructed the synthesis of a set of HDAC6-selective inhibitors containing the more desirable mercaptoacetamide moiety. Biological evaluation of these new compounds showed an IC50 in the nanomolar range, dose-dependent HDAC6 inhibition in MM1.S cells and improved genotoxicity results, rendering these new inhibitors valuable hits for applications even beyond oncology.