Stereoselective HDAC inhibition from cysteine-derived zinc-binding groups

Area of Science:

• Medicinal Chemistry
• Neuroscience
• Biochemistry

Background:

• Histone deacetylase (HDAC) inhibitors are investigated for therapeutic potential.
• Existing HDAC inhibitors, such as hydroxamic acids, can exhibit neurotoxicity.
• There is a need for novel neuroprotective agents with improved safety profiles.

Purpose of the Study:

• To synthesize and evaluate novel small-molecule HDAC inhibitors.
• To assess the neuroprotective efficacy of these compounds in a cellular model of neurodegeneration.
• To investigate the structure-activity relationships, particularly concerning cysteine enantiomers.

Main Methods:

• Synthesis of small-molecule HDAC inhibitors featuring cysteine-derived zinc-binding groups (ZBGs).
• Enzymatic assays to determine HDAC isoform inhibition (IC50 values).
• Cellular assays to evaluate neuroprotection against oxidative stress-induced cell death.
• Molecular modeling to explore enantiomeric differences in inhibitory activity.

Main Results:

• Compound 10 demonstrated potent HDAC inhibition with IC50 values below 1 microM.
• Many synthesized inhibitors provided significant neuroprotection (near-complete) at 10 microM.
• Cysteine-derived inhibitors were less toxic than hydroxamic acid-based compounds.
• L-cysteine derivatives inhibited HDACs, while D-cysteine derivatives did not, yet both showed neuroprotection.

Conclusions:

• Cysteine-derived HDAC inhibitors represent a promising class of neuroprotective agents.
• The differential activity of L- and D-cysteine enantiomers suggests multiple mechanisms of neuroprotection.
• These novel inhibitors may offer an improved therapeutic window compared to existing agents.