Eupatin, a Flavonoid, Inhibits Coronavirus 3CL Protease and Replication

Area of Science:

• Pharmacology
• Virology
• Natural Products Chemistry

Background:

• The COVID-19 pandemic highlights the urgent need for effective treatments against emerging coronaviruses.
• Existing vaccines necessitate complementary antiviral strategies due to continuous viral variant evolution.

Purpose of the Study:

• To investigate the antiviral properties of eupatin, a compound isolated from Inula japonica.
• To determine if eupatin inhibits coronavirus replication and its mechanism of action.

Main Methods:

• Isolation of eupatin from Inula japonica.
• In vitro assays to assess inhibition of SARS-CoV-2 3CL protease.
• Computational modeling to predict eupatin's interaction with the protease.
• Viral plaque assays and measurement of viral RNA and protein levels using human coronavirus OC43 (HCoV-OC43).

Main Results:

• Eupatin was isolated from Inula japonica flowers.
• Eupatin demonstrated inhibition of SARS-CoV-2 3CL protease, with computational modeling supporting interaction with key residues.
• Treatment with eupatin reduced viral plaque formation in HCoV-OC43 infected cells.
• Eupatin treatment led to decreased levels of viral protein and RNA.

Conclusions:

• Eupatin exhibits antiviral activity against coronaviruses.
• Eupatin inhibits coronavirus replication, likely through interaction with the 3CL protease.
• Inula japonica may be a source of novel antiviral compounds.