Stability of nitrofuran derivatives to cysteine, gastro-intestinal contents and light

Abstract

Stability of a series of nitrofuran derivatives against cysteine, content of digestive tract, and light was examined. 1) (a) Nitrofuran derivatives are decomposed by the SH group of cysteine (H3N+·R·S-). There is a certain relationship between the chemical structure and stability against cysteine (Chart 1).[chemical formula] (b) Stability of the derivatives with vinylog structure can be improved to some extent by N-oxygenation of the hetrocyclic nitrogen. (c) There is a positive correlation between stability to cysteine and therapeutic effect of typhoid-infected mice by oral administration in derivatives with vinylog structure. 2) Nitrofuran derivatives are decomposed by the content in the digestive tract lower than the small intestine and this decomposition is especially marked by cecal content. This decomposition is due to insoluble protein, enzyme, or bacterial SH in the content of the digestive tract. 3)(a) Nitrofuran derivatives in aqueous solution are decomposed by sunlight. Relationship between chemical structure and stability to light is approximately similar to that in the case of cysteine but not completely identical. (b) Stability of the aqueous solution to light depends on the concentration of derivatives, stability being better the higher the concentration. (c) Stability of the derivatives in various solvents became better with higher dielectric constant of the solvent. 4) Decomposition products of nitrofuran derivatives have no antibacterial activity.