Repurposing existing drugs: identification of SARS-CoV-2 3C-like protease inhibitors

Wei Chung Chiou, Meng Shiuan Hsu, Yun Ti Chen, Jinn-Moon Yang, Yeou-Guang Tsay, Hsiu Chen Huang, Cheng Huang*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is responsible for coronavirus disease 2019 (COVID-19). Since its emergence, the COVID-19 pandemic has not only distressed medical services but also caused economic upheavals, marking urgent the need for effective therapeutics. The experience of combating SARS-CoV and MERS-CoV has shown that inhibiting the 3-chymotrypsin-like protease (3CLpro) blocks the replication of the virus. Given the well-studied properties of FDA-approved drugs, identification of SARS-CoV-2 3CLpro inhibitors in an FDA-approved drug library would be of great therapeutic value. Here, we screened a library consisting of 774 FDA-approved drugs for potent SARS-CoV-2 3CLpro inhibitors, using an intramolecularly quenched fluorescence (IQF) peptide substrate. Ethacrynic acid, naproxen, allopurinol, butenafine hydrochloride, raloxifene hydrochloride, tranylcypromine hydrochloride, and saquinavir mesylate have been found to block the proteolytic activity of SARS-CoV-2 3CLpro. The inhibitory activity of these repurposing drugs against SARS-CoV-2 3CLpro highlights their therapeutic potential for treating COVID-19 and other Betacoronavirus infections.

Original languageEnglish
Pages (from-to)147-153
Number of pages7
JournalJournal of Enzyme Inhibition and Medicinal Chemistry
Issue number1
StatePublished - Jan 2021


  • 3CLpro inhibitors
  • antiviral
  • FRET
  • repurposing drugs
  • SARS-CoV-2 3CL protease


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