In Vitro Anti-SARS-CoV-2 Activities of Curcumin and Selected Phenolic Compounds

Since the COVID-19 pandemic in 2020, many reports have highlighted several potential anti-SARS-CoV-2 drug candidates, including phenolic compounds. Therefore, this study aimed to evaluate the anti-SARS-CoV-2 activity of nine common phenolic compounds found in plants using the in vitro cellular infection model. The anti-SARS-CoV-2 activity of curcumin, quercetin, gallic acid, catechin, rutin, kaempferol, naringenin, coumaric acid and caffeic acid were evaluated on SARS-CoV-2-infected Vero E6 cells by using a cytopathic effect (CPE)-based assay. The anti-SARS-CoV-2 activity in human lung cells, A549 expressing human ACE2 and TMPRSS2, was evaluated by the RT-qPCR technique. S1-ACE2 interaction and 3CL protease activity assays were also performed for the potent compound. Of the nine phenolic compounds, only curcumin inhibited the SARS-CoV-2 induced CPE activity (EC50 of 13.63 & mu;M) in Vero E6 cells, but with a low selective index (SI) value. Interestingly, curcumin exhibited potent anti-SARS-CoV-2 activity in A549 cells with an EC50 of 4.57 & mu;M and an SI value of 7.96. S1-ACE2 interaction and 3CL protease inhibitory activities of curcumin were also observed. In conclusion, curcumin showed a moderate in vitro anti-SARS-CoV-2 activity. The true potential of curcumin as an anti-SARS-CoV-2 candidate could be further evaluated in a COVID-19 animal model.