TMPRSS2 and COVID-19: In parallel studies, Hariprasad et al. (2020) tested the virtual interaction between many plant secondary metabolites and four target proteins involved in COVID-19, the host protease TMPRSS2 and the three virus proteins, Spike, main protease, and RNA-dependent RNA polymerase, and predicted among the class of triterpenoids the most active compounds in blocking the Spike-binding site.