Evaluation of antiviral compounds for inhibition of SARS-CoV-2 replication in vitro

Introduction:Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), mainly affects the human respiratory system.Even with the available treatments, more efficient therapeutic drugs are necessary.We have synthesized a series of compounds from two different classes that have shown promising activity against viruses and other microrganisms and propose to test them against SARS-CoV-2.Objectives: Evaluate a series of compounds synthesized by us, belonging to two different chemical classes (Class I and Class II), regarding their antiviral activity against SARS-CoV-2 replication in vitro and their cellular toxicity.Methodology: Vero E6 cells were infected with the original SARS-CoV-2 isolate MOI 0.01 and further treated with Class I and Class II compounds for 48 hours.Virus titration was further performed by plaque assay.Lactate dehydrogenase (LDH) assay was used to evaluate cytotoxicity.Results: To investigate the 5 Class I and 14 Class II derivatives, we initially performed a screening using a high concentration (100M) of the compounds for the treatment of the infected cells.Titration of viral particles showed that 4 Class I and 7 Class II compounds showed reduction of SARS-CoV-2 replication by at least 80%.After that, we selected the three most potent derivatives to determine their IC 50 (6.25,12.5, 25, 50, 100, 200 M) and CC 50 (25, 50, 100, 200, 400, 600, 1600 M).Our preliminary data show that the selected compounds reduce viral replication by 2 logs and have no significant cytotoxicity in the higher tested concentrations. Conclusion:The results demonstrated that Class I and Class II compounds have potent antiviral activity and low toxicity.Our studies open a new perspective for the inhibition of SARS-CoV-2 infection, with the characterization of a new antiviral compounds.Further analysis will determine compounds selectivity index, viral variants efficacy and potential sinergy with double treatment with approved antivirals.