Potential of plant extracts in targeting SARS-CoV-2 main protease: an in vitro and in silico study

The deaths caused by the covid-19 pandemic have recently decreased due to a worldwide effort in vaccination campaigns. However, even vaccinated people can develop a severe form of the disease that requires ICU admission. As a result, the search for antiviral drugs to treat these severe cases has become a necessity. In this context, natural products are an interesting alternative to synthetic medicines used in drug repositioning, as they have been consumed for a long time through traditional medicine. Many natural compounds found in plant extracts have already been shown to be effective in treating viral and bacterial diseases, making them possible hits to exploit against covid-19. The objective of this work was to evaluate the antiviral activity of different plant extracts available in the library of natural products of the Universidade Estadual de Maringa, by inhibiting the SARS-CoV-2 main protease (M-pro), and by preventing viral infection in a cellular model. As a result, the extract of Cytinus hypocistis, obtained by ultrasound, showed a M-pro inhibition capacity greater than 90%. In the infection model assays using Vero cells, an inhibition of 99.6% was observed, with a selectivity index of 42.7. The in silico molecular docking simulations using the extract compounds against M-pro, suggested Tellimagrandin II as the component of C. hypocistis extract most likely to inhibit the viral enzyme. These results demonstrate the potential of C. hypocistis extract as a promising source of natural compounds with antiviral activity against covid-19.Communicated by Ramaswamy H. Sarma

Automated summary

The deaths caused by covid-19 have decreased due to vaccination efforts, but severe cases still exist. Therefore, the search for antiviral drugs is crucial. Natural products, such as plant extracts, have shown potential in treating viral diseases. This study evaluated the antiviral activity of different plant extracts and found that Cytinus hypocistis extract had a high inhibition capacity against the SARS-CoV-2 main protease and viral infection in a cellular model. These results highlight the potential of C. hypocistis as a source of natural compounds with antiviral activity against covid-19.