sodium-nitrite and 4-diazoquinone

Protein and its components in high concentrations similar to those found in the digestive tract effectively scavenged nitrite and thus inhibited the formation of mutagens from nitrite. Various amino acids at 100 mM, bovine serum albumin (BSA) and trypsinized casein at 100 mg/ml effectively decreased the nitrite level of 50 mM-nitrite solution at pH 3 and 37 degrees C. Most, but not all, amino acids can convert nitrite into nitrogen gas; Pro can be converted into non-mutagenic nitrosoproline, CySH to S-nitrosocysteine, Trp to weakly mutagenic nitrosotryptophan and Tyr to non-mutagenic diazotyrosine. BSA was cross-linked, probably owing to the reaction of Tyr and Lys residues. Most amino acids inhibited more than 50% of nitrosodimethylamine formation in the reaction between 200 mM-dimethylamine and 50 mM-nitrite at pH 3 and 37 degrees C; BSA inhibited 50% of nitrosodimethylamine formation, and trypsinized casein, 100%. Most amino acids inhibited more than 50% of p-diazoquinone formation in the reaction between 25 mM-phenol and 100 mM-nitrite at pH 3 and 37 degrees C; BSA inhibited 80%, and trypsinized casein, 95% of such formation. Trypsinized casein effectively inhibited the development of the mutagenic effects attributable to the formation of diazobamethan from bamethan and nitrite.

Topics: Amino Acids; Animals; Caseins; Cattle; Chromatography, High Pressure Liquid; Dietary Proteins; Dimethylnitrosamine; Mutagenicity Tests; Mutagens; Quinones; Salmonella typhimurium; Serum Albumin; Sodium Nitrite

Reaction of phenol with nitrite under mildly acidic conditions produced p-nitrosophenol, p-diazoquinone and o-diazoquinone. p-Diazoquinone showed mutagenicity in Salmonella typhimurium strains TA98 and TA100 without metabolic activation; the number of his+ revertant colonies in strain TA98 was 85 with a dose of 20 nmol (after deduction of the background (control) number of about 20). Higher doses of the compound were bactericidal. While the reaction of phenol with an equivalent amount of nitrite at pH 3 produced p-nitrosophenol in high yield, reaction with excess nitrite produced a high yield of p-diazoquinone. p-Nitrosophenol was converted to p-diazoquinone by reaction with nitrite. Formation of o-diazoquinone also increased with increasing amounts of nitrite. The formation of these compounds was not greatly affected by the presence of dimethylamine. Nitrosation of dimethylamine with nitrite was stimulated by phenol because of the formation of p-nitrosophenol and its stimulatory effect. Thus, the reaction of phenol with nitrite can produce mutagenic p-diazoquinone, and can also stimulate nitrosation of secondary amines by production of p-nitrosophenol.

Topics: Chromatography; Hydrogen-Ion Concentration; Mutagenicity Tests; Mutagens; Nitrites; Nitroso Compounds; Phenol; Phenols; Quinones; Sodium Nitrite; Spectrum Analysis