Synthesis of α-Ketoamide-Based Stereoselective Calpain-1 Inhibitors as Neuroprotective Agents

Ammar Jastaniah, Irina N. Gaisina, Rachel C. Knopp, Gregory R.J. Thatcher

Research output: Contribution to journalArticlepeer-review

4 Scopus citations


Calpain inhibitors have been proposed as drug candidates for neurodegenerative disorders, with ABT-957 entering clinical trials for Alzheimer's disease and mild cognitive impairment. The structure of ABT-957 was very recently disclosed, and trials were terminated owing to inadequate CNS concentrations to obtain a pharmacodynamic effect. The multistep synthesis of an α-ketoamide peptidomimetic inhibitor series potentially including ABT-957 was optimized to yield diastereomerically pure compounds that are potent and selective for calpain-1 over papain and cathepsins B and K. As the final oxidation step, with its optimized synthesis protocol, does not alter the configuration of the substrate, the synthesis of the diastereomeric pair (R)-1-benzyl-N-((S)-4-((4-fluorobenzyl)amino)-3,4-dioxo-1-phenylbutan-2-yl)-5-oxopyrrolidine-2-carboxamide (1 c) and (R)-1-benzyl-N-((R)-4-((4-fluorobenzyl)amino)-3,4-dioxo-1-phenylbutan-2-yl)-5-oxopyrrolidine-2-carboxamide (1 g) was feasible. This allowed the exploration of stereoselective inhibition of calpain-1, with 1 c (IC50=78 nM) being significantly more potent than 1 g. Moreover, inhibitor 1 c restored cognitive function in amnestic mice.

Original languageEnglish (US)
Pages (from-to)2280-2285
Number of pages6
Issue number23
StatePublished - Dec 3 2020
Externally publishedYes


  • alpha-ketoamides
  • calpain
  • chirality
  • cysteine proteases
  • peptidomimetics

ASJC Scopus subject areas

  • Biochemistry
  • Molecular Medicine
  • Pharmacology
  • Drug Discovery
  • Pharmacology, Toxicology and Pharmaceutics(all)
  • Organic Chemistry


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