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PubMed1982

Quantitative comparisons between carcinogenicity, mutagenicity and electrophilicity of direct-acting N-nitroso compounds and other alkylating agents.

The quantitative relationship between carcinogenicity in rodents and mutagenicity in S. typhimurium was examined using 10 monofunctional alkylating agents, including N-nitrosamides, alkylmethane sulfonates and epoxides. The compounds were assayed for mutagenicity in two S. typhimurium strains (TA1535, TA100) and in plate and liquid assays. Mutagenic activity was compared with alkylating activity, half-life (solvolysis constant) and carcinogenic activity in rodents (TD50). No correlations between these variables were found. However, there was a good positive relationship between the TD50 values of the carcinogens and the initial ratios of N-7-alkylguanine to 0(6)-alkylguanine formed after reaction with double-stranded DNA in vitro (r = 0.88, p less than 0.01; n = 9). From these results, it is concluded that the N-7/0(6)-alkylguanine ratio is quantitatively related to the carcinogenic activity for this class of compounds and it may therefore be used to predict the carcinogenic potency of new compounds within this class.

Alkylating Agents↗
PubMed1984

On-line combination of high-performance liquid chromatography and total N-nitroso determination apparatus for the determination of N-nitrosamides and other N-nitroso compounds, and some recent data on the levels of N-nitrosoproline in foods and beverages.

A simple high-performance liquid chromatographic chemiluminescence detection method has been developed for the quantitative determination of N-nitrosamides and is based on post-column denitrosation of the compounds with hydrogen bromide-acetic acid or hydrogen iodide-acetic acid, followed by detection of the liberated NO by a chemiluminescence detector (TEATM). The method was used for the simultaneous analysis of DiazaldR, N-nitroso-N-methylurea, N-methyl-N'-nitro-N-nitrosoguandine and streptozotocin standards, and for N-methyl-N-nitrosourea extracted from model-system reaction mixtures and spiked, cured meats. The minimum detection limit of N-methyl-N-nitrosourea was about 0.5 ng. The method for the determination of N-nitrosarcosine and N-nitrosoproline in foods and beverages has been improved by replacing diazomethane with a mixture of BF3-methanol as the esterifying reagent and by simplifying the clean-up technique for purifying the prepared methyl esters. The average levels of N-nitrosoproline detected in 11 malts, 37 beers, 11 samples of fried bacon and 18 cured-meat products were found to be 24.1 micrograms/kg (5-113), 1.7 micrograms/kg (undetectable-6.0), 19.0 micrograms/kg (0.9-67.5), and 3.2 micrograms/kg (undetectable-21.6), respectively.

Amino Acids↗
PubMed1971

Environmental nitroso compounds: reaction of nitrite with creatine and creatinine.

Creatine reacts with nitrite under acid conditions to produce first sarcosine and then N-nitrososarcosine, which is a weak carcinogen in the rat. Creatinine reacts with acidified nitrite to produce either creatinine-5-oxime or 1-methylhydantoin-5-oxime, depending on reaction conditions. The toxicity and environmental significance of these compounds is not yet known.

Carcinogens↗