Xenobiotic acyl-coenzymes A: critical intermediates in the biochemical pharmacology and toxicology of carboxylic acids.

ronidazole. The reduction of the nitro group to the amine cesults in the total loss of mutagenic activity. Furthermore, once the amine is formed, it is not re-activated like those of other aromatic amines. In conclusion, the major ronidazole-protein adduct contains a reduced nitro function, has lost the carbamoyl group, and is alkylated by cysteine at the 2-methylene or 4-position. These structural alterations strongly suggest that the protein-bound adduct has lost all the mutagenic potential associated with the parent nitroimidazole. Similar structure-activity relationships in protein binding and mutagenicity suggest that the same reactive species is responsible for both biological events.