In the present study, we hypothesized that small molecules quercetin, glabridin, gallic acid, and chrysoeriol, derived from active ingredients of TCM recipes proven effective in treating COVID-19 (11), protect against COVID-19 by inhibiting viral receptors of ACE2 and TMPRSS2 on endothelial cells, thus regulating expression of NOX2 and MCP-1, as well as endothelial cell production of superoxide. Here, ACE2 is linked to COVID-19.