Peptidomimetic α-Acyloxymethylketone Warheads with Six-Membered Lactam P1 Glutamine Mimic: SARS-CoV-2 3CL Protease Inhibition, Coronavirus Antiviral Activity, and in Vitro Biological Stability

J Med Chem. 2022 Feb 24;65(4):2905-2925. doi: 10.1021/acs.jmedchem.1c00616. Epub 2021 Jul 9.


Recurring coronavirus outbreaks, such as the current COVID-19 pandemic, establish a necessity to develop direct-acting antivirals that can be readily administered and are active against a broad spectrum of coronaviruses. Described in this Article are novel α-acyloxymethylketone warhead peptidomimetic compounds with a six-membered lactam glutamine mimic in P1. Compounds with potent SARS-CoV-2 3CL protease and in vitro viral replication inhibition were identified with low cytotoxicity and good plasma and glutathione stability. Compounds 15e, 15h, and 15l displayed selectivity for SARS-CoV-2 3CL protease over CatB and CatS and superior in vitro SARS-CoV-2 antiviral replication inhibition compared with the reported peptidomimetic inhibitors with other warheads. The cocrystallization of 15l with SARS-CoV-2 3CL protease confirmed the formation of a covalent adduct. α-Acyloxymethylketone compounds also exhibited antiviral activity against an alphacoronavirus and non-SARS betacoronavirus strains with similar potency and a better selectivity index than remdesivir. These findings demonstrate the potential of the substituted heteroaromatic and aliphatic α-acyloxymethylketone warheads as coronavirus inhibitors, and the described results provide a basis for further optimization.

Publication types

  • Research Support, N.I.H., Extramural
  • Research Support, Non-U.S. Gov't
  • Research Support, U.S. Gov't, Non-P.H.S.

MeSH terms

  • Antiviral Agents / chemical synthesis
  • Antiviral Agents / chemistry
  • Antiviral Agents / pharmacology*
  • COVID-19 / metabolism
  • COVID-19 Drug Treatment
  • Coronavirus 3C Proteases / antagonists & inhibitors*
  • Coronavirus 3C Proteases / metabolism
  • Cysteine Proteinase Inhibitors / chemical synthesis
  • Cysteine Proteinase Inhibitors / chemistry
  • Cysteine Proteinase Inhibitors / pharmacology*
  • Glutamine / chemistry
  • Glutamine / pharmacology
  • Humans
  • Ketones / chemistry
  • Ketones / pharmacology
  • Microbial Sensitivity Tests
  • Molecular Structure
  • Peptidomimetics / chemistry
  • Peptidomimetics / pharmacology*
  • SARS-CoV-2 / drug effects*
  • SARS-CoV-2 / enzymology
  • Virus Replication / drug effects


  • Antiviral Agents
  • Cysteine Proteinase Inhibitors
  • Ketones
  • Peptidomimetics
  • Glutamine
  • 3C-like protease, SARS coronavirus
  • Coronavirus 3C Proteases

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