sodium-nitrite and dibutylamine

A kinetic study of the formation of N-nitrosodibenzylamine (NDBzA), from the nitrosation of dibenzylamine (DBzA) by sodium nitrite, was performed in a model system under conditions (temperature, pH) that are similar to those encountered in the industrial production of hams processed in elastic rubber nettings. The nitrosation reaction was carried out in a KH2PO4 buffer (0.5 M) at pH 5.8 and at a temperature of 69 degrees C. Since DBzA is insoluble in an aqueous buffer system, a non-ionic surfactant, Tween 20, was used as a solubilizing agent. The nitrosation reaction exhibited first-order kinetics with respect to DBzA and second-order kinetics with respect to nitrite. The calculated rate constant was 4.7 +/- 0.5 M-2/min. The pH profile of NDBzA formation was also determined. The optimal pH of NDBzA formation, 3.12, was close to the pKa of nitrous acid (HNO2, pKa = 3.1).

Topics: Benzylamines; Butylamines; Chromatography, Gas; Hydrogen-Ion Concentration; Kinetics; Models, Chemical; Nitrosamines; Nitrosation; Sodium Nitrite

The potential carcinogenic effect of nitrosamine precursors, DBA (dibutylamine) and nitrite, was clearly demonstrated pathologically in the liver and bladder of male Swiss albino mice. Benign tumours were induced in the bladder with an incidence of 40%, and hepatomas were detected in the liver in 27% of the cases. The protective effect of soybean and ascorbic acid, added separately to the diet or to the drinking water respectively, was demonstrated by a marked reduction in dysplastic features and absence of tumour in both the liver and the urinary bladder.

Topics: Animals; Ascorbic Acid; Butylamines; Glycine max; Liver; Liver Neoplasms, Experimental; Male; Mice; Mice, Inbred Strains; Nitrites; Sodium Nitrite; Urinary Bladder; Urinary Bladder Neoplasms

Endogenous formation of N-nitrosodi-n-butylamine (NDBA) was studied in rats after administration of sodium nitrite or sodium nitrate and N,N-dibutylamine (DBA) by monitoring the urinary excretion of NDBA and its metabolites, N-butyl-N-(4-hydroxybutyl)-nitrosamine (BBN) and N-butyl-N-(3-carboxypropyl)nitrosamine (BCPN). Animals were given sodium nitrite (0.2%) or sodium nitrate (0.5%), dissolved in the drinking-water. This treatment was started 24 h before DBA administration and was continued throughout the experiment. Animals were fasted overnight before receiving DBA, which was administered by gavage as three doses of 50 mg/kg, 8 h apart; 24-h urine samples were collected on ammonium sulfamate. NDBA, BBN and BCPN were extracted and analysed by GC-TEA, according to a method previously described. Under the experimental conditions reported, NDBA and BBN (free or glucuronic acid-conjugated) were not detected in the urine of animals given nitrite or nitrate and DBA, but the presence of BCPN indicated that N-nitrosation had occurred in both groups of animals. These results suggest that, when studying nitrosamines that are extensively metabolized, quantitative analysis of urinary metabolites is a better indicator of nitrosamine exposure than measurement of nitrosamine itself.

Topics: Animals; Butylamines; Butylhydroxybutylnitrosamine; Environmental Exposure; Male; Nitrates; Nitrosamines; Rats; Sodium Nitrite