New ribonucleotide reductase inhibitors with antineoplastic activity.

possible cancer chemotherapeutic agents. Howeven, pre himinary data indicate that these compounds are toxic and are not effective in humans (4, 14). In order to develop an effective chemothemapeutic agent for which the mode of action is inhibition of nibonucleotide meductase activity, a number of ahiphatic and aromatic hydroxamic acids and their corresponding amides and esters were synthesized and evaluated for inhibition of nibonucleotide meductaseand for their ability to prolong the life span of Ll210-leukemic mice. Several polyhydroxybenzohydroxamic acids and some of their corresponding amides and esters were found to be more effective inhibitors of nibonucleotide meductase than was hydmoxyurea. Additionally, several of these compounds increased the life span of L1210-leukemic mice to a greater extent and at a lower dosage than did hydroxyumea on a similar regimen.