Novel Benzohydroxamate-Based Potent and Selective Histone Deacetylase 6 (HDAC6) Inhibitors Bearing a Pentaheterocyclic Scaffold: Design, Synthesis, and Biological Evaluation

J Med Chem. 2019 Dec 12;62(23):10711-10739. doi: 10.1021/acs.jmedchem.9b01194. Epub 2019 Nov 25.


Histone deacetylase 6 (HDAC6) is a peculiar HDAC isoform whose expression and functional alterations have been correlated with a variety of pathologies such as autoimmune disorders, neurodegenerative diseases, and cancer. It is primarily a cytoplasmic protein, and its deacetylase activity is focused mainly on nonhistone substrates such as tubulin, heat shock protein (HSP)90, Foxp3, and cortactin, to name a few. Selective inhibition of HDAC6 does not show cytotoxic effects in healthy cells, normally associated with the inhibition of Class I HDAC isoforms. Here, we describe the design and synthesis of a new class of potent and selective HDAC6 inhibitors that bear a pentaheterocyclic central core. These compounds show a remarkably low toxicity both in vitro and in vivo and are able to increase the function of regulatory T cells (Tregs) at well-tolerated concentrations, suggesting a potential clinical use for the treatment of degenerative, autoimmune diseases and for organ transplantation.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Animals
  • Cell Survival / drug effects
  • Drug Design
  • Gene Expression Regulation, Enzymologic / drug effects
  • Histone Deacetylase 6 / antagonists & inhibitors*
  • Histone Deacetylase 6 / genetics
  • Histone Deacetylase 6 / metabolism
  • Histones / metabolism
  • Hydroxamic Acids / chemistry*
  • Mice
  • Protein Isoforms
  • Spleen / cytology
  • T-Lymphocytes, Regulatory
  • Tubulin / genetics
  • Tubulin / metabolism


  • Histones
  • Hydroxamic Acids
  • Protein Isoforms
  • Tubulin
  • HDAC6 protein, human
  • Hdac6 protein, mouse
  • Histone Deacetylase 6
  • benzohydroxamic acid