Identification of a Novel Small Molecule Inhibitor Against SARS Coronavirus Helicase

Abstract

A new chemical inhibitor against severe acute respiratory syndrome (SARS) coronavirus helicase, 7-ethyl-8-mercapto-3-methyl-3,7-dihydro-1H-purine-2,6-dione, was identified. We investigated the inhibitory effect of the compound by conducting colorimetry-based ATP hydrolysis assay and fluorescence resonance energy transfer-based double-stranded DNA unwinding assay. The compound suppressed both ATP hydrolysis and double-stranded DNA unwinding activities of helicase with IC50 values of 8.66 +/- 0.26 mu M and 41.6 +/- 2.3 mu M, respectively. Moreover, we observed that the compound did not show cytotoxicity up to 80 mu M concentration. Our results suggest that the compound might serve as a SARS coronavirus inhibitor.