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

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.