Therapeutic potential of Cordyceps militaris mushroom against SARS-CoV-2 : Virtual screening against Mpro and in vitro validation

Pathogenic coronavirus, including COVID-19, threatens human health, and there are strong demands for efficient therapeutics. Cordyceps militaris is a medicinal mushroom that has long been used for immune enhancement, anticancer, and antiviral effects. Therefore, the inhibitory potentials of constituents of C. militaris against COVID-19 were analyzed using various virtual screening analyses. Among ten constituents of C. militaris, cordycepin, the major component, and 3´-deoxyuridine and 2´-O-methyl-adenosine showed strong binding affinity to Mpro, a potential target for COVID-19 therapeutics. Considering the structure activity relationship, nucleosides having deoxyribose and methoxyribose moiety are important for the affinity to Mpro. Cordycepin is also bound to Mpro mutants, and the binding mechanisms between cordycepin and Mpro were further demonstrated by MD simulation, RMSA, and MM/PBSA analysis. Principal component analysis also confirmed the conformational change of Mpro by cordycepin, which inhibits the function of Mpro. In vitro, the efficacy of cordycepin was measured using Vero cells infected with SARS-CoV-2, which showed excellent inhibition with an IC50 value of 29 μM. Conclusively, the constituents of C. militaris are expected to inhibit SARS-CoV-2 replication through binding to Mpro. Therefore, C. militaris can be an important therapeutic for coronavirus through the synergistic effect of its constituents.