A 2020 study concluded that nitric oxide, a cell-signaling molecule that the body produces naturally, could be a potential treatment for COVID-19 by giving relief to patients and even containing the spread of SARS-CoV-2 coronavirus.
The study, conducted in Sweden, found direct evidence that nitric oxide inhibits the replication of SARS-CoV-2. The scientists found that nitric oxide inhibited a key enzyme called 3C-like protease (3CLpro) that the virus SARS-CoV-2 needs to make copies of itself.
The 3CL protease (3CLpro) is the main protease of the SARS-CoV-2, which is responsible for the viral replication.
“we have evaluated the in vitro antiviral effect of NO on SARS-CoV-2 replication. The NO-donor S-nitroso-N-acetylpenicillamine (SNAP) had a dose dependent inhibitory effect on SARS-CoV-2 replication, while the non S-nitrosated NAP was not active, as expected. Although the viral replication was not completely abolished (at 200 μM and 400 μM), SNAP delayed or completely prevented the development of viral cytopathic effect in treated cells, and the observed protective effect correlated with the level of inhibition of the viral replication. The capacity of the NO released from SNAP to covalently bind and inhibit SARS-CoV-2 3CL recombinant protease in vitro was also tested. The observed reduction in SARS-CoV-2 protease activity was consistent with S-nitrosation of the enzyme active site cysteine.”
“In this study, we demonstrated that NO can inhibit the replication of SARS-CoV-2 in Vero E6 and we identified the SARS-CoV-2 main protease as a target for NO. There is a great need for effective antivirals against SARS-CoV-2 to be used in the on-going COVID-19 pandemic. Based on this study and previous studies on SARS-CoV in vitro, and in a small clinical trial, we conclude that NO may be applied for clinical use in the treatment of COVID-19 and other human coronavirus infections.” research paper Mitigation of the replication of SARS-CoV-2 by nitric oxide in vitro, published October 2020