Table 2.
Anti-SARS-CoV-2 RdRp/ExoN activities (along with respective ratios) of the target repurposed drugs riboprine, forodesine, nelarabine, tecadenoson, maribavir, and vidarabine (using both remdesivir and molnupiravir as the positive control/reference drugs, and dimethylsulfoxide “DMSO” as the negative control/placebo drug), respectively, in HEK293T cells, expressed as EC50 values in μM (please note that, in this table, nsp12 refers to nsp12/7/8 complex, nsp14 refers to nsp14/10 complex, and nsp14mutant refers to nsp14mutant/10 complex)
| Classification | Compound Name | Inhibition of SARS-CoV-2 RdRp in vitro (EC50 in μM)a | Respective Ratios of EC50 | |||
|---|---|---|---|---|---|---|
| Nsp12 | Nsp12 + Nsp14 | Nsp12 + Nsp14mutant | (Nsp12 + Nsp14)/Nsp12 |
(Nsp12 + Nsp14mutant)/Nsp12 |
||
| Repurposed NAs | Riboprine | 0.21 ± 0.03 | 0.30 ± 0.03 | 0.25 ± 0.03 | 1.43 | 1.19 |
| Forodesine | 0.23 ± 0.03 | 0.33 ± 0.04 | 0.27 ± 0.03 | 1.44 | 1.17 | |
| Nelarabine | 0.63 ± 0.05 | 1.20 ± 0.07 | 1.07 ± 0.06 | 1.91 | 1.70 | |
| Tecadenoson | 0.95 ± 0.06 | 1.34 ± 0.08 | 1.26 ± 0.07 | 1.41 | 1.33 | |
| Maribavir | 1.05 ± 0.06 | 1.88 ± 0.08 | 1.43 ± 0.08 | 1.79 | 1.36 | |
| Vidarabine | 1.07 ± 0.05 | 2.00 ± 0.07 | 1.44 ± 0.05 | 1.87 | 1.35 | |
| Reference Drugs | Remdesivir | 1.12 ± 0.06 | 2.10 ± 0.08 | 1.56 ± 0.07 | 1.88 | 1.39 |
| Molnupiravir | 0.28 ± 0.03 | 0.48 ± 0.04 | 0.35 ± 0.04 | 1.71 | 1.25 | |
| Placebo Solvent | DMSO | >100 | >100 | >100 | N.A.b | N.A. |
aEC50 or 50% effective concentration is the concentration of the tested compound that is required for 50% reduction in the COVID-19 polymerase (SARS-CoV-2 RdRp) activity in vitro. EC50 is expressed in μM
bN.A. means not available (i.e., it was not determined)