Metabolism-Based Drug Discovery: Novel Benzothiazepine-Containing HDAC6 Inhibitor as a Potential Neuroprotective...

Area of Science:

• Medicinal Chemistry
• Neuropharmacology
• Biochemistry

Background:

• Histone deacetylase 6 (HDAC6) inhibition is a key strategy for treating central nervous system diseases.
• Previous brain-penetrant HDAC6 inhibitor 5 exhibited metabolic instability, necessitating further optimization.

Purpose of the Study:

• Identify metabolic sites of inhibitor 5.
• Optimize the structure of inhibitor 5 to enhance metabolic stability and potency.
• Evaluate the neuroprotective efficacy of the optimized inhibitor 8k.

Main Methods:

• Structure-based drug design and synthesis.
• In vitro enzymatic assays for HDAC6 inhibition and selectivity.
• In vitro metabolic stability assays using rat liver microsomes.
• In silico molecular docking to assess HDAC6 complex stabilization.
• In vitro cell-based assays measuring acetylated α-tubulin levels.
• In vivo studies using a rat middle cerebral artery occlusion (MCAO) model for ischemic stroke.

Main Results:

• Compound 8k potently and selectively inhibited HDAC6 (IC50 = 4.0 nM; >176-fold selectivity).
• 8k demonstrated a 2-fold longer half-life (29.49 min) in rat liver microsomes compared to compound 5.
• In silico analysis showed 8k stabilized the HDAC6 complex, and in vitro studies confirmed increased acetylated α-tubulin in SH-SY5Y cells.
• In vivo, 8k significantly reduced cerebral infarction by over 50% in the rat MCAO model.

Conclusions:

• 8k is a metabolically stable, highly selective HDAC6 inhibitor.
• 8k exhibits significant neuroprotective effects in an ischemic stroke model.
• 8k warrants further development as a potential therapeutic agent for ischemic stroke and other CNS diseases.