Discovery of a novel SARS-CoV-2 main protease inhibitor by a simple and optimized colorimetric screening assay

ABSTRACT

For rapid discovery of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) main protease (Mpro) inhibitors from a natural product library, a novel colorimetric screening assay was developed. According to the colorimetric principle, the synthetic peptide TSAVLQ-para-nitroanilide (pNA) was used as the Mpro hydrolysis substrate. Subsequently, the working concentration of pNA substrate, Mpro working concentration, hydrolysis time and DMSO tolerance were optimized for the development of a simple and robust colorimetric screening assay. Through these systematic optimizations, we selected 0.4 mumol.L-1 Mpro and 100 mumol.L-1 pNA substrate as the optimal working concentrations in this colorimetric screening assay, and a high Z' factor of 0.9 was achieved. Using this screening assay, natural product ginkgolic acid C13 0 (GA13 0) was identified as a novel competitive Mpro inhibitor in vitro. Taken together, we have successfully developed a simple and optimized colorimetric screening assay, which will be vital for the discovery of novel SARS-CoV-2 Mpro inhibitors. Copyright © 2022, Chinese Pharmaceutical Association. All rights reserved.