(5-Chloropyridin-3-yl) 1H-indole-4-carboxylate

An anti-coronaviral protease inhibitor.

Phase of research

Potential treatment - pre-clinical evidence

How it helps


Drug status


Supporting references
Contradictory references
AI-suggested references
Clinical trials

General information

(5-Chloropyridin-3-yl) 1H-indole-4-carboxylate is a chloropyridyl ester-derived SARS-CoV and SARS-CoV-2 3C-like protease covalent inhibitor with antiviral activities in micromolar concentrations in vitro (Ghosh et al, 2008; Hattori et al., 2021).

(5-Chloropyridin-3-yl) 1H-indole-4-carboxylate on PubChem


GRL-0496; GRL-1720


Structure image - (5-Chloropyridin-3-yl) 1H-indole-4-carboxylate


Supporting references

Link Tested on Impact factor Notes Publication date
Development of a Cell-Based Luciferase Complementation Assay for Identification of SARS-CoV-2 3CLpro Inhibitors
3CLpro Small molecule Enzyme assay In vitro
in vitro enzyme assay 3.82

The compound inhibited the SARS-CoV-2 3C-like protease in vitro with maximum inhibition of 24% relative to the inhibition by 100 μM GC376 and it showed CC50 of 53.2 μM.

A small molecule compound with an indole moiety inhibits the main protease of SARS-CoV-2 and blocks virus replication
Crystallization Small molecule Enzyme assay In vitro In silico
in silico; in vitro enzyme asay; in vitro biophysical assay; crystallization; Calu-3 cells, peripheral blood mononuclear cells, and human bronchial/tracheal epithelial cells (cytotoxicity assays); Vero E6 cells; SARS-CoV-2 strain JPN/TY/WK-521 12.12

The compound potently inhibited the SARS-CoV-2 3C-like protease (3CLpro) in vitro (IC50 of ca. 0.32 μM) without detectable cytotoxicity at 200 μM. The compound’s EC50 value for Vero E6 cells was ca 15 μM. Using mass spectrometry and fluorimetry techniques, it was found to form a covalent bond with 3CLpro.