Design, Synthesis, In Vitro Evaluation, and Molecular Docking of 4-Substituted Anilides as Histone Deacetylase...

Histone deacetylases (HDAC) overexpression is associated with oncogenesis. Hence, HDAC inhibitors are a promising class of compounds for targeted cancer therapy. Some HDAC inhibitors, such as vorinostat (SAHA), are already approved for the treatment of hematologic cancer. A number of 4-substituted anilides (para-aminophenol or para-aminobenzoic acid derivatives) were designed and synthesized as potential HDAC inhibitors. Compound 23e behaved as a potent HDAC2 inhibitor (IC₅₀ = 4.2 nM) with greater activity than SAHA. Molecular docking results showed that the ligand 23e well placed to the HDAC2 active site through both hydrogen (Gly32, Asp104, Gly154, and His183) and hydrophobic (His33, Pro34, Phe155, His183, and Phe210) interactions. Molecular dynamics simulations confirmed stable complex formation over 500 ns with only small adaptive conformational fluctuations upon ligand binding. MM/PBSA analysis indicated a favorable binding free energy (ΔG_bind = -27.98 kcal/mol), confirming a thermodynamically stable and dynamically compatible protein-ligand interaction. Compound 23e exhibited a pronounced antiproliferative effect comparable to SAHA against HeLa and Raji cells, with IC₅₀ values of 5.07 ± 0.09 µM and 1.87 ± 0.22 µM, respectively, with low toxicity on normal cells. The synthesized derivatives can be considered as potential compounds for further development.