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microsome test
155 Samples thus obtained must be checked for possible solvent residues or other factors which may interact with in vitro tests. For some complex substances as lipids, for instance, it is furthermore necessary to check whether the substance penetrates the test organism. This can be done by using lipids as a positive control and chemically determining the lipid content in the test organism.
6 GSggelmann, W., and K.-H. Summer, Abteilung ffir Toxikologie, Gesellschaft fib Strahlen- und Umweltforschung, D-8042 Neuherberg-Munich (West-Germany) 1-Chloro-2,4~iinitrobenzene, mutagenicity and binding to glutathione 1-Chloro-2,4-dinitrobenzene (CDNB) is a reactive compound used to study cell-mediated immunity and to treat Alopecia areata. CDNB is a direct mutagen for Salmonella typhimurium TA1538, TA100 and TA98 (Summer and GSggelmann, Mutation Res., (1979) in press). CDNB binds to glutathione (GSH). This reaction is catalyzed by GSH S-transferases. The level of GSH and the activity of GSH S-transferases in Salmonella typhimurium strains TA1535, TA100, TA1538 and TA98 amounted to 11 nmole/mg protein and 9 nmole/mg X min, respectively. Although CDNB was bound to bacterial GSH, the GSH concentration of the bacteria in the Ames test was not sufficient to prevent mutagenicity of 0.05 mM CDNB. Mutagenicity of CDNB decreased in the presence of rat $9 fraction since $9 contains high levels of GSH and GSH S-transferases. However, high concentrations of CDNB overwhelmed its inactivation by GSH-binding, whereas GSH in excess abolished CDNB mutagenicity. These results demonstrate that the binding of electrophilic compounds to GSH may influence their mutagenicity in the Ames test. Especially in the presence of $9 fractions, small amounts of test compounds may lead to falsenegative results of the test.
7 Herbold, B.A., and D. Lorke, Institut fiir Toxikologie der Bayer AG, D-5600 Wuppertal 1 (West-Germany) On the mutagenicity of artificial sweeteners and their main impurities examined in the Salmonella/microsome test
Animated by the positive findings of Stoltz et al. (1977) in the Salmonella/ microsome test on the mutagenic activity of some impurities in saccharin, we have initiated studies on some products. Cyclamate, cyclohexylamine, saccharin, boiled saccharin, 3 organic extracts of this artificial sweetener and 9 possible impurities including OTS and PTS have been examined for their mutagenic activities in the Ames test with doses up to at least 2500 #g per plate with and without $9 mix. In order to produce metabolic activation $9 fractions from induced livers of Aroclor-treated male Sprague-Dawley rats have been applied to the test system. As indicator organisms the Salmonella tester strains
6 GSggelmann, W., and K.-H. Summer, Abteilung ffir Toxikologie, Gesellschaft fib Strahlen- und Umweltforschung, D-8042 Neuherberg-Munich (West-Germany) 1-Chloro-2,4~iinitrobenzene, mutagenicity and binding to glutathione 1-Chloro-2,4-dinitrobenzene (CDNB) is a reactive compound used to study cell-mediated immunity and to treat Alopecia areata. CDNB is a direct mutagen for Salmonella typhimurium TA1538, TA100 and TA98 (Summer and GSggelmann, Mutation Res., (1979) in press). CDNB binds to glutathione (GSH). This reaction is catalyzed by GSH S-transferases. The level of GSH and the activity of GSH S-transferases in Salmonella typhimurium strains TA1535, TA100, TA1538 and TA98 amounted to 11 nmole/mg protein and 9 nmole/mg X min, respectively. Although CDNB was bound to bacterial GSH, the GSH concentration of the bacteria in the Ames test was not sufficient to prevent mutagenicity of 0.05 mM CDNB. Mutagenicity of CDNB decreased in the presence of rat $9 fraction since $9 contains high levels of GSH and GSH S-transferases. However, high concentrations of CDNB overwhelmed its inactivation by GSH-binding, whereas GSH in excess abolished CDNB mutagenicity. These results demonstrate that the binding of electrophilic compounds to GSH may influence their mutagenicity in the Ames test. Especially in the presence of $9 fractions, small amounts of test compounds may lead to falsenegative results of the test.
7 Herbold, B.A., and D. Lorke, Institut fiir Toxikologie der Bayer AG, D-5600 Wuppertal 1 (West-Germany) On the mutagenicity of artificial sweeteners and their main impurities examined in the Salmonella/microsome test
Animated by the positive findings of Stoltz et al. (1977) in the Salmonella/ microsome test on the mutagenic activity of some impurities in saccharin, we have initiated studies on some products. Cyclamate, cyclohexylamine, saccharin, boiled saccharin, 3 organic extracts of this artificial sweetener and 9 possible impurities including OTS and PTS have been examined for their mutagenic activities in the Ames test with doses up to at least 2500 #g per plate with and without $9 mix. In order to produce metabolic activation $9 fractions from induced livers of Aroclor-treated male Sprague-Dawley rats have been applied to the test system. As indicator organisms the Salmonella tester strains