N-phenethylphenazine-1-carboxamide, a novel antiviral compound against infectious bronchitis virus

Avian infectious bronchitis virus (IBV) is a globally prevalent and highly contagious avian pathogen that imposes significant disease burden and economic losses on the poultry industry. Given the challenges associated with current vaccine-based immunization strategies, there is an urgent need to develop novel therapeutic approaches for the prevention and treatment of IBV infection. In this study, a newly synthesized compound, N-phenethylphenazine-1-carboxamide (SQXA-12), was evaluated for its potent inhibitory effects on IBV replication. The cytotoxicity assay revealed CC₅₀ values of 151.2 µM in H1299 cells, 147.0 µM in Vero cells, 96.83 µM in DF-1 cells, 166.6 µM in HeLa cells, and 136.7 µM in Mac-145 cells, while the EC₅₀ value of SQXA-12 was determined to be 12.25 µM. Sensitivity tests against a panel of viruses, including vesicular stomatitis virus (VSV), human coronavirus OC43 (HCoV-OC43), porcine epidemic diarrhea virus (PEDV), Newcastle disease virus (NDV), porcine reproductive and respiratory syndrome virus (PRRSV), and avian influenza virus H9N2 (AIV-H9N2), demonstrated that SQXA-12 exhibits potential broad-spectrum antiviral activity against both positive- and negative-sense RNA viruses. Collectively, these findings underscore the promising therapeutic potential of SQXA-12 for the treatment of IBV infection.