Researchers wanted to study the effect grapefruit seed extract had on SARS-CoV-2 to see if it was a potential inhibitor of molecular docking. Using in silico method they found that, "antiviral activity of grapefruit extract, both fractional and combined suggest it could be used as a highly biologically potent adjuvant treatment for COVID-19." The study also concluded that natural extracts ‘have proven to be more effective as treatment (antibacterial or cytotoxic) than synthetically obtained pure derivatives.

Saric, B., Tomic, N., Kalajdzic, A., Pojskic, N., & Pojskic, L. (2021). In silico analysis of selected components of grapefruit seed extract against SARS-CoV-2 main protease. The EuroBiotech Journal, 5(s1), 5-12.