Antiviral activity of N-phenyl-N'-aryl- or alkylthiourea derivatives in Coxsackie virus infections in mice.

The effect of five derivatives of N-phenyl-N'-aryl- or alkylthiourea-inhibitors of the multiplication of Coxsackie virus B1 and other picornaviruses in vitro-was tested in experimental infections with Coxsackie viruses B1, B3, A6, and A7 in newborn mice. Under the action of N-phenyl-N'-3-hydroxyphenylthiourea (no. 23) and N-phenyl-N'-4-carboxy-5-hydroxyphenylthiourea (no. 20) a two- to threefold reduction in mortality was observed, as well as an appreciable delay in the course of the disease (mean effective dose, lengthening by 2 to 6 days) after infection with Coxsackie viruses B1, B3, and A7. The infection with Coxsackie virus A6 was affected only by compound no. 23 and, at that, to a low degree. If the antiviral effect is to be obtained, the compounds must be applied daily (once subcutaneously) from the 24th to the 144th h after virus inoculation, a period which corresponds to the incubation period and the beginning of the manifested infection. On the basis of these data, as well as of the relatively high selectivity (therapeutic index of 3 to 20), the two indicated substances may be considered to be reliable antiviral chemotherapeutic agents.