Caracemide (NSC-253272) inhibits the enzyme ribonucleotide reductase of Escherichia coli. Caracemide is a novel anticancer agent derived from a hydroxamic acid and has demonstrated to produce severe central nervous system (CNS) toxicity[1][2].
Caracemide inactivates R1 by covalent modification at the substrate-binding site and has a toxic metabolite, methylisocyanate (MIC), in vivo[1][2].
The mercapturic acid derivative AMCC was identified in urine rats following administration to rats of a single i.p. dose (6.6 mg/kg) of caracemide (NSC-253272)[1]. .
[1]. Slatter JG, et al. Studies on the metabolic fate of caracemide, an experimental antitumor agent, in the rat. Evidence for the release of methyl isocyanate in vivo. Chem Res Toxicol. 1993 May-Jun;6(3):335-40. [2]. Larsen IK, et al. Caracemide, a site-specific irreversible inhibitor of protein R1 of Escherichia coli ribonucleotide reductase. J Biol Chem. 1992 Jun 25;267(18):12627-31.