Crucial Structural Understanding for Selective HDAC8 Inhibition: Common Pharmacophores, Molecular Docking, Molecular Dynamics, and Zinc Binder Analysis of Selective HDAC8 Inhibitors

Background: Overexpression of HDAC8 was observed in various cancers and inhibition of HDAC8 has emerged as a promising therapeutic approach in recent decades. Objective: This review aims to facilitate the discovery of novel selective HDAC8 inhibitors by analyzing the structural scaffolds of 66 known selective HDAC8 inhibitors, along with their IC₅₀values against HDAC8 and other HDACs. Methods: The inhibitors were clustered based on structural symmetry, and common pharmacophores for each cluster were identified using Phase. Molecular docking with all HDACs was performed to determine binding affinity and crucial interacting residues for HDAC8 inhibition. Representative inhibitors from each cluster were subjected to molecular dynamics simulation to analyze RMSD, RMSF, active site amino acid residues, and crucial interacting residues responsible for HDAC8 inhibition. The study reviewed the active site amino acid information, active site cavities of all HDACs, and the basic structure of Zn²⁺binding groups. Results: Common pharmacophores identified included AADHR_1, AADDR_1, ADDR_1, ADHHR_1, and AADRR_1. Molecular docking analysis revealed crucial interacting residues: HIS-142, GLY-151, HIS-143, PHE-152, PHE-208 in the main pocket, and ARG-37, TYR-100, TYR-111, TYR-306 in the secondary pocket. The RMSD of protein and RMSF of active site amino acid residues for stable protein-ligand complexes were less than 2.4 Å and 1.0 Å, respectively, as identified from MD trajectories. The range of Molecular Mechanics Generalized Born Surface Area (MM-GBSA) ΔG predicted from MD trajectories was between -15.8379 Å and -61.5017 Å kcal/mol. Conclusion: These findings may expedite the rapid discovery of selective HDAC8 inhibitors subject to experimental evaluation.