Anisodamine potently inhibits SARS-CoV-2 infection in vitro and targets its main protease.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) provoked a pandemic of acute respiratory disease, namely coronavirus disease 2019 (COVID-19). Currently, effective drugs for this disease are urgently warranted. Anisodamine is a traditional Chinese medicine that is predicted as a potential therapeutic drug for the treatment of COVID-19. Therefore, this study aimed to investigate its antiviral activity and crucial targets in SARS-CoV-2 infection. SARS-CoV-2 and anisodamine were co-cultured in Vero E6 cells, and the antiviral activity of anisodamine was assessed by immunofluorescence assay. The antiviral activity of anisodamine was further measured by pseudovirus entry assay in HEK293/hACE2 cells. Finally, the predictions of crucial targets of anisodamine on SARS-CoV-2 were analyzed by molecular docking studies. We discovered that anisodamine suppressed SARS-CoV-2 infection in Vero E6 cells, and reduced the SARS-CoV-2 pseudovirus entry to HEK293/hACE2 cells. Furthermore, molecular docking studies indicated that anisodamine may target SARS-CoV-2 main protease (M(pro)) with the docking score of -6.63 kcal/mol and formed three H-bonds with Gly143, Cys145, and Cys44 amino acid residues at the predicted active site of M(pro). This study suggests that anisodamine is a potent antiviral agent for treating COVID-19.