A NOVEL CLASS of ANTIVIRAL COMPOUNDS with POTENT ACTIVITY AGAINST SARS-CoV-2

Background: The SARS-CoV-2 pandemic has sickened over 245 million people, and has killed more than 5 million worldwide. Recent data proves that vaccinations are highly effective in preventing Covid-19 disease, however antigenic drift and other functional mutations in the virus genome reduce the efficacy of vaccines, indicating that the development of antiviral treatments remain a crucial priority. We report potent antiviral activity against SARS-CoV-2 for a promising, novel class of nitrogen-based heterocyclic compounds. Methods: 232 compounds based on the same class of nitrogen-based hetereocyclic molecules were synthesized to final purity of greater than 99%. This library was screened for antiviral phenotypes in a cytopathic effect (CPE) assay using VeroE6 cells and the SARS-CoV-2 WA1 isolate. Based on the results of the WA1 CPE screen, 47 lead candidates were structurally analyzed, and this information was utilized to design 56 additional compounds. A second antiviral CPE-based screen was performed using these 103 candidates in VeroE6 cells with the SARS-CoV-2 delta variant. Antiviral assays studying SARS-CoV-1 (Urbani) and MERS-CoV were performed in Vero 76 cells utilizing a Neutral Red cytopathic effect assay. Results: Within the same class of structurally related small molecules, we tested an initial set of 232 compounds using a CPE-based assay with VeroE6 cells and the USA/WA1 SARS-CoV-2 isolate. Of the compounds tested, 124 demonstrated potency 10 to 540-times higher than a Remdesivir control tested in parallel. Importantly, we observed no detectable toxicity for the vast majority of these compounds when tested up to a concentration of 30 μ M. The lead candidate in this screen displayed an IC50 of 0.02 μ M and a selectivity index of >1,500. Based on structural analysis of an initial 47 lead candidates, we synthesized 56 new molecules, and tested all 103 in a CPE-based assay using the delta variant, also observing efficacy against this variant of concern. Examples of this same class of compounds also display antiviral activity against SARS-CoV-1 (Urbani) and MERS-CoV in cell-based assays. Conclusion: We have identified a novel class of antiviral compounds with potent activity against SARS-CoV-2. High potency against both the early WA1 isolate and the more recent delta variant, as well as efficacy against SARS-CoV-1 and MERS-CoV, suggest that this class of antiviral compounds has pan-Coronavirus antiviral activity.

Recent studies of nitrogen containing heterocyclic compounds as novel antiviral agents: A review.

N-heterocycles are important, not only because of their abundance, but above all because of their chemical, biological and technical significance. They play an important role in biological investigation such as anticancer, antiinflammatory, antibacterial, antiviral, anti-tumor, antidiabetic, etc. In this study, we focused on examining synthesized some 5- or 6-ring N-heterocyclic compounds that showed the antiviral activity in last 5 years, and investigation of these compounds structure-activity relationship studies. This review will be useful to scientists in research fields of organic synthesis, medicinal chemistry, and pharmacology.