Myricetin-bound crystal structure of the SARS-CoV-2 helicase NSP13 facilitates the discovery of novel natural inhibitors

Acta Crystallogr D Struct Biol. 2025 Jun 1;81(Pt 6):310-326. doi: 10.1107/S2059798325004498. Epub 2025 May 27.

Abstract

The SARS-CoV-2 helicase NSP13 is a highly conserved and essential component of the viral replication machinery, making it a promising target for antiviral drug development. Here, we present the 2 Å resolution crystal structure of NSP13 bound to the natural flavonoid myricetin, revealing a conserved allosteric binding site. Guided by these structural findings, a virtual screening campaign identified the caffeic acid derivatives rosmarinic acid and chlorogenic acid as potential novel natural inhibitors, which were experimentally validated to inhibit RNA-unwinding activity. This study provides structural insights that could support ongoing drug-discovery efforts targeting NSP13 in SARS-CoV-2 and other coronaviruses with pandemic potential.

Keywords: NSP13 helicase; SARS-CoV-2; antiviral drug development; caffeic acid derivatives; myricetin; natural inhibitors; virtual screening.

MeSH terms

  • Allosteric Site
  • Antiviral Agents* / chemistry
  • Antiviral Agents* / pharmacology
  • Binding Sites
  • Chlorogenic Acid / chemistry
  • Chlorogenic Acid / pharmacology
  • Cinnamates / chemistry
  • Cinnamates / pharmacology
  • Crystallography, X-Ray
  • Depsides / chemistry
  • Depsides / pharmacology
  • Drug Discovery
  • Flavonoids* / chemistry
  • Flavonoids* / metabolism
  • Flavonoids* / pharmacology
  • Humans
  • Methyltransferases
  • Models, Molecular
  • Protein Binding
  • Protein Conformation
  • RNA Helicases* / antagonists & inhibitors
  • RNA Helicases* / chemistry
  • RNA Helicases* / metabolism
  • Rosmarinic Acid
  • SARS-CoV-2* / drug effects
  • SARS-CoV-2* / enzymology
  • Viral Nonstructural Proteins* / antagonists & inhibitors
  • Viral Nonstructural Proteins* / chemistry
  • Viral Nonstructural Proteins* / metabolism

Substances

  • myricetin
  • Viral Nonstructural Proteins
  • RNA Helicases
  • Flavonoids
  • Antiviral Agents
  • Nsp13 protein, SARS-CoV
  • Cinnamates
  • Depsides
  • Chlorogenic Acid
  • Rosmarinic Acid
  • Methyltransferases