Mercaptoamide-based non-hydroxamic acid type histone deacetylase inhibitors

Inhibitors of histone deacetylases (HDAC) are emerging as a promising class of anti-cancer agents. A mercaptoamide functionality was designed as a bidentate zinc chelator and incorporated into the hydroxamic acid based SAHA (1) scaffold in order to identify non-hydroxamate compounds as potential inhibitors of histone deacetylases. Two sets of mercaptoamides 2 and 3 with varying spacer length were synthesized and their HDAC inhibitory activity was evaluated. Low micromolar inhibition was observed for mercaptoamides 2e, 3b, and 3d.