Abstract
4-[(1,2-Dihydro-2-oxo-3H-indol-3-ylidene)amino]-N-(4,6-dimethylpyrimidin-2-yl) benzenesulphonamide and its derivatives were tested in vitro for antiviral activity against vaccinia and cowpox virus replication in human foreskin fibroblast (HFF) cells, and their activity was compared with cidofovir (CDV). Among the tested compounds, 4-[(5-methyl-1,2-dihydro-2-oxo-3-H-indol-3-ylidene)amino]-N-(4,6-dimethylpyrimidin-2-yl)benzene-sulphonamide was the most active against vaccinia virus, with a 50% effective concentration (EC50) value of 18 µM and 4-[(N-acetyl-1,2–dihydro-2-oxo-3-H-indol-3-ylidene)amino]-N-(4,6-dimethylpyrimidin-2-yl) benzenesulphonamide was the most active against cowpox virus (EC50=33 µM). Cidofovir was found to have an EC50 of 20 µM and 32 µM against vaccinia and cowpox virus, respectively. Most of the tested compounds were non-cytotoxic (>300 µM) in HFF cells as determined by a neutral red uptake assay. The substitution of a halogen atom at the 5-position of isatin abolished the antiviral activity.