Direct gas chromatographic analysis of cyclic N-nitrosamines

Apparent mutagenicity of N-nitrosothiazolidine caused by a trace contaminant

The identification of N-nitrosothiazolidine (NTHZ) in smoked meat products prompted us to evaluate this compound for mutagenicity by the Salmonella assay. NTHZ was prepared in 99 + % purity by the nitrosation of the cysteamine-formaldehyde reaction mixture without isolation and purification of the resulting amine, and from thiazolidine, directly. Mutagenic activity was observed with TA100 without metabolic activation in the former, but not the latter preparation. An examination of the precursors, reaction intermediates, and HPLC separation of the NTHZ from the mutagenic product demonstrated that the genotoxic activity resulted from a synthesis-produced trace contaminant.

Genotoxicity of N-nitrosothiazolidine in microbial and hepatocellular test systems

The genotoxicity of N-nitrosothiazolidine was studied in a microbial system and in a hepatocellular system. The compound showed positive responses in both tests, exhibiting weak mutagenicity at the lowest level tested (1 mg/plate) in the rec assay in Bacillus subtilis, and inducing statistically significant levels of DNA repair in primary hepatocyte cultures at concentrations ranging from 2 X 10(-4) to 2 X 10(-3) M.

Mutagenicity of 2-hydroxyalkyl-N-nitrosothiazolidines

The mutagenicity of 2-hydroxyalkyl-N- nitrosothiazolidines was tested using Salmonella typhimurium strains TA98 and TA100. The N- nitrosothiazolidines tested were unsubstituted N- nitrosothiazolidine (NT), N- nitrosothiazolidine -4-carboxylic acid ( NTC ), 2-hydroxymethyl-N- nitrosothiazolidine ( HMNT ), 2-(1,2,3,4- tetrahydroxybutyl )-N- nitrosothiazolidine , 2-(1,2,3,4- tetrahydroxypentyl )-N- nitrosothiazolidine , 2-(1,2,3,4,5- pentahydroxypentyl )-N- nitrosothiazolidine ( PHPNT ) and 2-(1,2,3,4,5- pentahydroxypentyl )-N- nitrosothiazolidine -4-car boxylic acid. Among the N- nitrosothiazolidines tested, only HMNT and PHPNT exhibited clear dose-response mutagenicity toward strain TA100 with or without metabolic activation. None of the 2-hydroxyalkyl-N- nitrosothiazolidines were mutagenic to strain TA98. NT exhibited much stronger mutagenicity than either HMNT or PHPNT . Mutagenic activities of NT and PHPNT were eliminated by carboxyl substitution in the position alpha to the N-nitroso group.