9-Amino minocycline inhibits SARS-CoV-2 viral replication by targeting proteolytic and deubiquitinase activity of papain-like protease (PLpro) enzyme
Location
Suwanee, GA
Start Date
6-5-2025 1:00 PM
End Date
6-5-2025 4:00 PM
Description
The 3-chymotrypsin-like protease (3CLpro), papain-like protease (PLpro), and RNA-dependent RNA polymerase (RdRp) are vital enzymes in SARS-CoV-2 replication and are targets for antiviral drugs. Presently, Paxlovid® and Lagevrio™ target 3CLpro and RdRp, respectively, for treating COVID-19. However, no drugs target PLpro, a crucial enzyme for viral replication and immune response preservation. This study identified 9-amino minocycline (9-AMN) as a potent inhibitor of SARS-CoV-2 PLpro. While minocycline alone did not inhibit these enzymes, introducing an amino group at the 9th carbon position led to over 90% inhibition of PLpro's proteolytic and deubiquitinase (DUB) functions, with IC50 values of 4.15µM and 4.55µM, respectively. Structural analysis revealed that 9-AMN binds to the catalytic site of PLpro, disrupting its proteolytic and DUB activities. Importantly, 9-AMN did not exhibit cytotoxicity against uninfected lung carcinoma cells at concentrations up to 50µM. Effectively reduced SARS-CoV-2 infection by 70% at 6.25µM concentration and caused only 25-35% cytotoxicity in infected cells. It also displayed an inhibitory effect against Delta and Omicron variants with IC50 values of 1.04µM and 2.35µM, respectively. Synergistic effects were observed when combining 9-AMN with EIDD-1931 the active component of FDA-approved pro drug Molnupiravir and Nirmatrelvir (PF-332), resulting in a significant reduction in required doses for similar potency against SARS-CoV-2 omicron infection in Calu-3 cells. In summary, these findings suggest that 9-AMN is a promising inhibitor of SARS-CoV-2 replication while preserving the host's immune response by suppressing PLpro's DUB activity. Nonetheless, pre-clinical investigations are necessary to evaluate its therapeutic viability and safety before potential clinical trials.
Embargo Period
5-19-2025
9-Amino minocycline inhibits SARS-CoV-2 viral replication by targeting proteolytic and deubiquitinase activity of papain-like protease (PLpro) enzyme
Suwanee, GA
The 3-chymotrypsin-like protease (3CLpro), papain-like protease (PLpro), and RNA-dependent RNA polymerase (RdRp) are vital enzymes in SARS-CoV-2 replication and are targets for antiviral drugs. Presently, Paxlovid® and Lagevrio™ target 3CLpro and RdRp, respectively, for treating COVID-19. However, no drugs target PLpro, a crucial enzyme for viral replication and immune response preservation. This study identified 9-amino minocycline (9-AMN) as a potent inhibitor of SARS-CoV-2 PLpro. While minocycline alone did not inhibit these enzymes, introducing an amino group at the 9th carbon position led to over 90% inhibition of PLpro's proteolytic and deubiquitinase (DUB) functions, with IC50 values of 4.15µM and 4.55µM, respectively. Structural analysis revealed that 9-AMN binds to the catalytic site of PLpro, disrupting its proteolytic and DUB activities. Importantly, 9-AMN did not exhibit cytotoxicity against uninfected lung carcinoma cells at concentrations up to 50µM. Effectively reduced SARS-CoV-2 infection by 70% at 6.25µM concentration and caused only 25-35% cytotoxicity in infected cells. It also displayed an inhibitory effect against Delta and Omicron variants with IC50 values of 1.04µM and 2.35µM, respectively. Synergistic effects were observed when combining 9-AMN with EIDD-1931 the active component of FDA-approved pro drug Molnupiravir and Nirmatrelvir (PF-332), resulting in a significant reduction in required doses for similar potency against SARS-CoV-2 omicron infection in Calu-3 cells. In summary, these findings suggest that 9-AMN is a promising inhibitor of SARS-CoV-2 replication while preserving the host's immune response by suppressing PLpro's DUB activity. Nonetheless, pre-clinical investigations are necessary to evaluate its therapeutic viability and safety before potential clinical trials.