Design, synthesis, and cytotoxicity evaluation of novel indole-acylhydrazone derivatives of 4-pyridinone as potential histone deacetylase-2 inhibitors

Background and purpose: Histone deacetylation is one of the essential cellular pathways in the growth and spread of cancer, so the design of histone deacetylase (HDAC) inhibitors as anticancer agents is of great importance in pharmaceutical chemistry. Here, a series of indole acylhydrazone derivatives of 4-pyridone have been introduced as potential histone deacetylase inhibitors. Experimental approach: Seven indole-acylhydrazone-pyridinone derivatives were synthesized via simple, straightforward chemical procedures. The molecular docking studies were accomplished on HDAC2 compared to panobinostat. The cytotoxicity of all derivatives was studied on MCF-7 and MDA-MB-231 breast cancer cell lines by MTT assay. Findings / Results: Molecular docking studies supported excellent fitting to the HADC2 active site with binding energies in the range of -10 Kcal/mol for all derivatives. All compounds were tested for their cytotoxicity against MCF-7 and MDA-MB-231 cell lines; derivatives A, B, F, and G were the best candidates. The half-maximal inhibitory concentration (IC 50) values on MCF-7 were below 25 mg/mL and much lower than those obtained on the MDA-MB-231 cell line. Conclusion and implications: The derivatives showed selectivity toward the MCF-7 cell line, probably due to the higher HDAC expression in the MCF-7 cell line. In this regard, debenzylated derivatives F and G showed slightly better cytotoxicity, which should be more studied in the future. Derivatives A, B, F, and G were promising for future enzymatic studies.