2-Substituted 1,5-benzothiazepine-based HDAC inhibitors exert anticancer activities on human solid and acute myeloid leukemia cell lines

Abstract

Herein, we report the development of a new series of histone deacetylase inhibitors (HDACi) containing a 2-substituted 1,5-benzothiazepine scaffold. First, a virtual combinatorial library (∼1.6 × 10³ items) was built according to a convenient synthetic route, and then it was submitted to molecular docking experiments on seven HDACs isoforms belonging to classes I and II. Integrated computational filters were used to select the most promising ones that were synthesized through an optimized approach, also amenable to generating both racemic and enantioenriched benzothiazepine-based derivatives. The obtained compounds showed potent HDAC inhibitory activity, especially those containing the sulphone moiety, endowed with IC₅₀ in the nanomolar range. In addition, in vitro outcomes of our synthesized compounds demonstrated a cytotoxic effect on U937 and HCT116 cell lines and an arrest in the G2/M phase (13 ≤ IC₅₀ ≤ 18 µM). Finally, Western blot analyses outlined the modulation of the histone acetyl markers such as H3K9/14, acetyl-tubulin, and the apoptotic indicator p21 in both cancer cell lines, disclosing a good HDAC inhibitor activity exerted by the designed items. Given the key role of HDACs in many cellular pathways, which makes these enzymes appealing and "hot" drug targets, our findings highlighted the importance of these 2-substituted 1,5-benzothiazepine-based compounds (both in the reduced and oxidized version) for the development of novel epidrugs.

Keywords: 2-substituted 1,5-benzothiazepine; Anticancer activity; Drug design; Enantioselective synthesis; HDAC; Molecular docking.