Virucidal activity of tiliacorinine, dioscorine, racemosol, and terrein against influenza A virus (H1N1), coronavirus 229E, SARS-CoV-2, and enterovirus 71.

Emerging infectious diseases such as COVID-19 and Disease X, which was detected in the Democratic Republic of the Congo in early December 2024, underscore the importance of developing new virucidal, antiviral, and antimicrobial compounds. The virucidal activity of natural products, including tiliacorinine (1), dioscorine (2), racemosol (3), and terrein (4), against influenza A virus (H1N1), human coronavirus 229E (HCoV-229E), severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2), and enterovirus 71 (EV71) were evaluated using the American Society for Testing and Materials E1053-20 method. Racemosol (3) from Bauhinia malabarica had the most potent virucidal activity against the H1N1, HCoV-229E, and SARS-CoV-2 viruses, followed by terrein (4), a metabolite of the fungus Aspergillus terreus. Racemosol (3) exhibited virucidal activity with a log reduction of 4 (99.99 % viral reduction) against H1N1, HCoV-229E, and SARS-CoV-2 at a concentration of 0.1250 mg/mL. The alkaloids tiliacorinine (1) from Tiliacora triandra and dioscorine (2) from Dioscorea hispida exhibited weaker virucidal activity than racemosol (3) and terrein (4). Compounds 1, 2, and 4 showed weak virucidal activity against the EV71 virus, while racemosol (3) displayed moderate activity with a log reduction of 3.813 at the concentration of 0.1250 mg/mL. This work underscores the importance of natural products as sources of virucidal agents, which may be useful for the future threats of emerging and re-emerging viral diseases.