Pyronaridine for COVID-19

AbstractThere are currently relatively few small-molecule antiviral drugs that are either approved or emergency approved for use against SARS-CoV-2. One of these is remdesivir, which was originally repurposed from its use against Ebola and functions by causing early RNA chain termination. We used this as justification to evaluate three molecules we had previously identified computationally with antiviral activity against Ebola and Marburg. Out of these we previously identified pyronaridine, which inhibited the SARS-CoV-2 replication in A549-ACE2 cells. Herein, the in vivo efficacy of pyronaridine has now been assessed in a K18-hACE transgenic mouse model of COVID-19. Pyronaridine treatment demonstrated a statistically significant reduction of viral load in the lungs of SARS CoV-2 infected mice. Furthermore, the pyronaridine treated group reduced lung pathology, which was also associated with significant reduction in the levels of pro-inflammatory cytokines/chemokine and cell infiltration. Notably, pyronaridine inhibited the viral PLpro activity in vitro (IC50 of 1.8 µM) without any effect on Mpro, indicating a possible molecular mechanism involved in its ability to inhibit SARS-CoV-2 replication. Interestingly, pyronaridine also selectively inhibits the host kinase CAMK1 (IC50 of 2.4 µM). We have also generated several pyronaridine analogs to assist in understanding the structure activity relationship for PLpro inhibition. Our results indicate that pyronaridine is a potential therapeutic candidate for COVID-19.One sentence summaryThere is currently intense interest in discovering small molecules with direct antiviral activity against the severe acute respiratory syndrome coronavirus 2 (SARS-Cov-2). Pyronaridine, an antiviral drug with in vitro activity against Ebola, Marburg and SARS-CoV-2 has now statistically significantly reduced the viral load in mice along with IL-6, TNF-α, and IFN-β ultimately demonstrating a protective effect against lung damage by infection to provide a new potential treatment for testing clinically.

ABSTRACT The coronavirus disease 2019 (COVID-19) pandemic, caused by severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), continues to be one of the largest dangers to human health around the world. The need for effective antiviral and anti-inflammatory treatments is still extremely high as newly emerging variants threaten the efficacy of currently used treatment options. Many compounds are effective at inhibiting SARS-CoV-2 infection in vitro but fail to recapitulate that efficacy in vivo . There is a major demand for antiviral drugs that are efficacious and broadly effective for the treatment of highly pathogenic coronaviruses including SARS-CoV-2, and its close relatives SARS-CoV-1 and Middle East respiratory syndrome coronavirus (MERS-CoV). One drug with the potential to join the small subset of broadly active antiviral compounds that is both efficacious in vivo and orally bioavailable is pyronaridine triphosphate, which has now been published to show both in vitro and in vivo efficacy in A549 cells and the K18-hACE2 mouse model, respectively, by functioning as a protease inhibitor of the SARS-CoV-2 papain-like protease (PLpro). In our studies, pyronaridine treatment resulted in significant improvements to lung inflammatory pathology, reducing pro-inflammatory cytokine and chemokine levels, and inhibiting weight loss seen in the mouse model associated with the severity of disease in three highly pathogenic coronavirus infection models, SARS-CoV-1, SARS-CoV-2, and MERS-CoV. Additionally, we found that pyronaridine treatment can safely and effectively be combined with currently used therapeutics molnupiravir and nirmatrelvir (main protease inhibitor component of Paxlovid) in a SARS-CoV-2 in vivo model, and there was evidence of a synergistic effect that further reduced viral titers, inflammatory lung pathology, and inflammatory cytokine and chemokine levels. These results indicate that pyronaridine represents an excellent potential therapeutic candidate for COVID-19 treatment individually, or in combination with other approved antivirals as well as a potential therapeutic option for the treatment of highly pathogenic coronaviruses such as SARS-CoV-1, MERS-CoV, and future coronaviruses yet to emerge. IMPORTANCE Pyronaridine tetraphosphate is on the WHO Essential Medicine List for its importance as a widely available and safe treatment for malaria. We find that pyronaridine is a highly effective antiviral therapeutic across mouse models using multiple variants of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2), and the highly pathogenic viruses SARS-CoV-1 and Middle East respiratory syndrome coronavirus responsible for previous coronavirus outbreaks. Additionally, we find that pyronaridine additively combines with..

AbstractThe ongoing pandemic caused by the novel severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), necessitates strategies to identify prophylactic and therapeutic drug candidates for rapid clinical deployment. Here, we describe a screening pipeline for the discovery of efficacious SARS-CoV-2 inhibitors. We screen a best-in-class drug repurposing library, ReFRAME, against two high-throughput, high-content imaging infection assays: one using HeLa cells expressing SARS-CoV-2 receptor ACE2 and the other using lung epithelial Calu-3 cells. From nearly 12,000 compounds, we identify 49 (in HeLa-ACE2) and 41 (in Calu-3) compounds capable of selectively inhibiting SARS-CoV-2 replication. Notably, most screen hits are cell-line specific, likely due to different virus entry mechanisms or host cell-specific sensitivities to modulators. Among these promising hits, the antivirals nelfinavir and the parent of prodrug MK-4482 possess desirable in vitro activity, pharmacokinetic and human safety profiles, and both reduce SARS-CoV-2 replication in an orthogonal human differentiated primary cell model. Furthermore, MK-4482 effectively blocks SARS-CoV-2 infection in a hamster model. Overall, we identify direct-acting antivirals as the most promising compounds for drug repurposing, additional compounds that may have value in combination therapies, and tool compounds for identification of viral host cell targets.