Mpro inhibitor N3 hemihydrate is a potent inhibitor of SARS-CoV-2 Mpro with an EC50 of 16.77 μM for SARS-CoV-2. Mpro inhibitor N3 hemihydrate specifically inhibits Mpro from multiple coronaviruses, including SARS-CoV and MERS-CoV. Mpro inhibitor N3 hemihydrate displays inhibition against HCoV-229E, FIPV, and MHV-A59 with individual IC50 of 4.0 μM, 8.8 μM, and 2.7 μM, respectively[1][2]. Mpro inhibitor N3 hemihydrate (0-0.64 μM) is able to penetrate cells to inhibit the replication of IBV viruses, probably at the beginning of infection in embryos[3]. [1]. Jin Z, et al. Structure of Mpro from SARS-CoV-2 and discovery of its inhibitors. Nature. 2020;582(7811):289-293.[2]. Yang H, et al. Design of wide-spectrum inhibitors targeting coronavirus main proteases [published correction appears in PLoS Biol. 2005 Nov;3(11):e428]. PLoS Biol. 2005;3(10):e324.[3]. Wang F, et al. Structure of Main Protease from Human Coronavirus NL63: Insights for Wide Spectrum Anti-Coronavirus Drug Design. Sci Rep. 2016;6:22677. Published 2016 Mar 7.