Phthalimide derivatives as a new class of papain-like protease inhibitors in SARS-CoV-2

Arch Pharm (Weinheim). 2025 Jan;358(1):e2400714. doi: 10.1002/ardp.202400714. Epub 2024 Dec 8.

Abstract

The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) papain-like cysteine protease (PLpro) represents one of only two essential cysteine proteases involved in the regulation of viral replication. It, therefore, qualifies as a promising therapeutic target for the development of antiviral agents. We identified a previously synthesized protease inhibitor, resulting from an earlier project, as a PLpro inhibitor and crafted a structure-activity relationship around the hit, leading to the more potent inhibitors ZHAWOC6941 (17h) and ZHAWOC25153 (17o) displaying IC50 values of 8 and 7 µM, respectively. The two compounds represent a new class of PLpro inhibitors and, with single-digit micromolar IC50 values, are comparable to inhibitors found in the literature.

Keywords: SARS‐CoV‐2; inhibitor; papain‐like protease; structure–activity relationship.

MeSH terms

  • Antiviral Agents* / chemical synthesis
  • Antiviral Agents* / chemistry
  • Antiviral Agents* / pharmacology
  • COVID-19 Drug Treatment
  • Coronavirus 3C Proteases / antagonists & inhibitors
  • Coronavirus 3C Proteases / metabolism
  • Coronavirus Papain-Like Proteases / antagonists & inhibitors
  • Coronavirus Papain-Like Proteases / chemistry
  • Cysteine Proteinase Inhibitors / chemical synthesis
  • Cysteine Proteinase Inhibitors / chemistry
  • Cysteine Proteinase Inhibitors / pharmacology
  • Humans
  • Inhibitory Concentration 50
  • Phthalimides* / chemical synthesis
  • Phthalimides* / chemistry
  • Phthalimides* / pharmacology
  • Protease Inhibitors / chemical synthesis
  • Protease Inhibitors / chemistry
  • Protease Inhibitors / pharmacology
  • SARS-CoV-2* / drug effects
  • SARS-CoV-2* / enzymology
  • Structure-Activity Relationship

Substances

  • Antiviral Agents
  • Phthalimides
  • Coronavirus Papain-Like Proteases
  • Cysteine Proteinase Inhibitors
  • Protease Inhibitors
  • papain-like protease, SARS-CoV-2
  • Coronavirus 3C Proteases