Biologic effects of isohydroxyurea.

SUMMARY Isohydroxyurea causes a rapid devitalization of E. coli C600. The effect of this agent on bacterial metabolism is manifested mainly in an inhibition in the synthesis of RNA. This is in marked contrast to the biologic action of the isomeric com pound, hydroxyurea, which is primarily bacteriostatic in na ture and which involves a specific block in DNA production. The lethal action of isohydroxyurea is accompanied by deg radation of cellular DNA. A bacterial strain resistant to the devitalizing action of the drug did not exhibit this degradation. This strain was still, however, blocked in its ability to synthe size RNA. Using bacterial strains resistant to either hydroxy urea or isohydroxyurea, a relationship based on cross resistances was established between the two compounds. A metabolic scheme seeking to relate these and other observa tions is proposed.