5-Ethynyl-1-beta-D-ribofuranosylimidazole-4-carboxamide (
EICAR) and 6'-(R)-6'-C-methylneplanocin A (
TJ13025) are two novel
antiviral agents which are targeted against
IMP dehydrogenase and
S-adenosylhomocysteine hydrolase, respectively. These compounds have been examined for their activities against various strains of orthomyxoviruses (influenza virus) and paramyxoviruses (
parainfluenza virus, mumps virus, measles virus, and respiratory syncytial virus) in vitro.
EICAR was 10- to 59-fold more active than
ribavirin and
TJ13025 was 32- to 330-fold more active than
ribavirin against
parainfluenza virus types (2 and 3), mumps virus, and measles virus.
EICAR was also more active than
ribavirin against respiratory syncytial virus and influenza virus, whereas
TJ13025 was virtually inactive against these viruses. The 50% virus-inhibitory concentrations of
EICAR and
TJ13025 were generally within the 0.1- to 1-microgram/ml range. Although the compounds did not prove cytotoxic to stationary host cells (HeLa, Vero, MDCK, and LLCMK2) at a concentration of 200 micrograms/ml, concentrations of 4 to 13 micrograms/ml inhibited the growth of dividing cells.
EICAR and
TJ13025 should be further pursued as candidate drugs for the treatment of ortho- and paramyxovirus
infections.