sodium-nitrite and 2-methyl-1-4-dinitropyrrole

Topics: Antioxidants; Ascorbic Acid; Food Microbiology; Food Preservatives; Hydroxylamines; Lactobacillus delbrueckii; Meat Products; Mutagens; Nitriles; Pyrroles; Sodium Nitrite; Sorbic Acid

Sorbic acid reacts with nitrite to yield mutagenic products such as 1,4-dinitro-2-methylpyrrole (NMP) and ethylnitrolic acid (ENA). In order to know the stability of these compounds, a kinetic study of their decomposition reactions was performed in the 6.0-9.5 pH range. The conclusions drawn are as follows: (i) The decomposition of NMP occurs through a nucleophilic attack by OH- ions, with the rate equation as follows: r = k(dec)NMP[OH-][NMP] with k(dec)NMP (37.5 degrees C) = 42 +/- 1 M(-1) s(-1). (ii) The rate law for the decomposition of ENA is as follows: r = k(dec)ENA[ENA]K(a)/(K(a) + [H+]), with K(a) being the ENA dissociation constant and k(dec)ENA (37.5 degrees C) = (7.11 +/- 0.04) x 10(-5) s(-1). (iii) The activation energies for NMP and ENA decomposition reactions are, respectively, E(a) = 94 +/- 3 and 94 +/- 1 kJ mol(-1). (iv) The observed values for the decomposition rate constants of NMP and ENA in the pH range of the stomach lining cells, into which these species can diffuse, are so slow that they could be the slow determining step of the alkylation mechanisms by some of the products resulting from NMP and ENA decomposition. Thus, the current kinetic results are consistent with the low mutagenicity of these species.

Topics: Hydroxylamines; Kinetics; Mutagens; Nitriles; Pyrroles; Sodium Nitrite; Sorbic Acid

1,4-Dinitro-2-methylpyrrole (DNMP), a mutagenic product formed by the interaction of two common food additives, sorbic acid and sodium nitrite, was transformed to 1-nitro-2-methyl-4-aminopyrrole (NMAP) by human fecal mixtures and various intestinal bacterial strains. Under anaerobic conditions the cell suspensions of Actinomyces, Bacteroides, Clostridium, Eubacterium, Fusobacterium, and Peptostreptococcus spp. demonstrated the nitroreduction activity. Under aerobic conditions, only Actinomyces and Bacteroides spp. showed activity, and this was at a decreased level. In cell suspensions of Bacteroides thetaiotaomicron VPI 5482, NAD(P)H and glucose accelerated the reduction rate, whereas dicoumarol and heat significantly inhibited the rate, and flavin adenine dinucleotide (FAD) and flavin mononucleotide (FMN) did not affect the rate. With cell-free preparations of the same strain, reduction required NAD(P)H as a cofactor in a dose-dependent fashion and was inactivated by air and heat.

Topics: Bacteria, Anaerobic; Bacteroides; Biotransformation; Chromatography, High Pressure Liquid; Chromatography, Thin Layer; Feces; Female; Humans; Intestines; Kinetics; Magnetic Resonance Spectroscopy; Male; Mutagens; Oxidation-Reduction; Pyrroles; Sodium Nitrite; Sorbic Acid

Topics: Ascorbic Acid; Cysteine; Fatty Acids, Unsaturated; Food Additives; Hydrogen-Ion Concentration; Kinetics; Mutagens; Nitrites; Oxidation-Reduction; Pyrroles; Salmonella typhimurium; Sodium Nitrite; Sorbic Acid

Conditions of the reaction between sorbic acid and sodium nitrite generating mutagenic principles were examined. In the rec-assay and the Ames reversion assay, the maximal mutagenic activity was obtained in a pH range of 3.5-4.2. Mutagenic and growth-inhibitor activities of five C-nitro and C-nitroso compounds were studied. The product Y, 2-methyl-1,4-dinitropyrrole, was the strongest mutagen among them.

Topics: Drug Interactions; Fatty Acids, Unsaturated; Hydrogen-Ion Concentration; Microsomes, Liver; Mutagenicity Tests; Mutagens; Nitrites; Nitro Compounds; Nitroso Compounds; Pyrroles; Salmonella typhimurium; Sodium Nitrite; Sorbic Acid