Tartell, M. | Search bioRxiv

bioRxiv2025

Inhibitors of membrane associated serine proteases block replication of coronavirus SARS-CoV-2 and influenza virus H1N1

TMPRSS2 is a membrane associated serine protease which is important in the viral pathogenesis of coronaviruses and influenza viruses. We developed mechanism-based covalent -ketobenzothiazole (kbt) inhibitors using substrate specificity PS-SCL screening of TMPRSS2 as a rational guide for inhibitor design. Three distinct focused libraries of tetrapeptide kbts were synthesized and evaluated for their inhibition of TMPRSS2, matriptase and other serine proteases. We also investigated different capping groups for the previously reported tripeptide inhibitor Ac-QFR-kbt (MM3144) to increase its selectivity over the blood coagulation protease factor Xa. The most potent compounds were tested for their ability to inhibit viral replication of SARS-CoV-2 coronavirus and the H1N1 influenza virus. The most active compounds were profiled for their pharmacokinetics (PK) in mice. Several promising new compounds were identified with improved potency, selectivity, and drug-like properties including Bz-QFR-kbt (CA1043) and Cbz-QFR-kbt (ZFH9141) with an IC50 of 150 nM and 60 nM for H1N1, respectively.

microbiology↗

bioRxiv2021

A novel class of TMPRSS2 inhibitors potently block SARS-CoV-2 and MERS-CoV viral entry and protect human epithelial lung cells

The host cell serine protease TMPRSS2 is an attractive therapeutic target for COVID-19 drug discovery. This protease activates the Spike protein of Severe Acute Respiratory Syndrome Coronavirus 2 (SARS-CoV-2) and of other coronaviruses and is essential for viral spread in the lung. Utilizing rational structure-based drug design (SBDD) coupled to substrate specificity screening of TMPRSS2, we have discovered a novel class of small molecule ketobenzothiazole TMPRSS2 inhibitors with significantly improved activity over existing irreversible inhibitors Camostat and Nafamostat. Lead compound MM3122 (4) has an IC50 of 340 pM against recombinant full-length TMPRSS2 protein, an EC50 of 430 pM in blocking host cell entry into Calu-3 human lung epithelial cells of a newly developed VSV SARS-CoV-2 chimeric virus, and an EC50 of 74 nM in inhibiting cytopathic effects induced by SARS-CoV-2 virus in Calu-3 cells. Further, MM3122 blocks Middle East Respiratory Syndrome Coronavirus (MERS-CoV) cell entry with an EC50 of 870 pM. MM3122 has excellent metabolic stability, safety, and pharmacokinetics in mice with a half-life of 8.6 hours in plasma and 7.5 h in lung tissue, making it suitable for in vivo efficacy evaluation and a promising drug candidate for COVID-19 treatment.

microbiology↗