The reaction of butylated hydroxyanisole and its metabolites with some arylamines: investigations of product mutagenicity

We examined t-butylhydroquinone (t-BHQ) and t-butylquinone (t-BuQ), two of the major microsomal metabolites of the synthetic antioxidant butylated hydroxyanisole (BHA), for their ability to react with the xenobiotic arylamines aniline and N-methylaniline. A number of substances were isolated by thin-layer chromatography. The main products were quantitatively evaluated and their structures assigned. BHA and t-BHQ yielded reaction products with anilines only in the presence of an oxidant such as iodate (KIO3). We used the Salmonella/microsome mutagenicity assay to test the new compounds for mutagenic activity. The reaction products gave no evidence of mutagenicity in the S. typhimurium strains TA98 and TA100, with or without metabolic activation. In some instances the substituted quinone products are less toxic than t-BuQ alone.

Antigenotoxic properties of lactic acid bacteria in the S. typhimurium mutagenicity assay

A high percentage of human tumors is reported to be related to dietary habits. One way to improve the nutritional impact is to increase the intake of protective factors, such as inhibitors of DNA damage and other types of anticarcinogens. Specific strains of lactic acid bacteria used to ferment milk are promising candidates that may be antimutagenic and anticarcinogenic. We have studied the antimutagenicity of 10 isolated strains of beneficial lactic acid bacteria. Four types of fermented milk products were also studied for their protective properties. The effect of these bacteria on the yield of revertants induced by nitrosated beef extract was investigated in the Salmonella typhimurium mutagenicity assay. Eight of 10 isolated Lactobacillus strains reduced the yield of his+ revertants almost back to the levels of the untreated controls. Different fermented fresh yogurts containing viable bacteria (probably Lactobacillus delbrueckii ssp. bulgaricus and Streptococcus thermophilus or Lactobacillus acidophilus and Bifidobacteria) showed protective effects as well. The degree of suppressing revertants was independent of the yogurt's fat content. In contrast, yogurt products that had been heat treated were not inhibitory. The other fresh fermented milk products (e.g., buttermilk, kefir, and "Dickmilch") were not antimutagenic in this study. The results imply that some bacteria used in milk processing have an antimutagenic potential and that this property is specific for the bacterial strain.

The possible role of probiotics as dietary antimutagen

Possible antimutagenic actions of probiotics--mainly lactic acid bacteria--were examined using in vitro and in vivo test systems. In the Ames test with Salmonella typhimurium TA1538 beef extract and nitrosated beef extract were used as mutagens. L. casei showed high antimutagenic activity on mutagenicity induced by nitrosated beef extract only without S9 mix, whereas Omniflora (a lyophilized preparation of lactobacilli and E. coli) and its cell-free culture broth exhibited antimutagenic action only on beef extract. The actions of probiotics were more homogeneous when living animals were used in the tests. Using busulfan as a mutagen both the chromosome aberration test (with Chinese hamster bone marrow cells) and the micronucleus test (with bone marrow cells of Chinese hamsters and mice) showed strong anticlastogenic action when L. casei, Omniflora or yoghurt (with living bifiobacteria) were given orally at the same time as the mutagen. Lactobacilli were effective also after i.p. injection. Cell-free culture broths had no or only weak antimutagenic effects. Mutagen-induced chromosome aberrations and micronuclei were reduced by up to 80% by the lactobacilli.

Re-examination of potassium sorbate and sodium sorbate for possible genotoxic potential

Potassium sorbate and sodium sorbate were investigated for possible genotoxic actions using the Salmonella/mammalian-microsome test, HGPRT and sister chromatid exchange (SCE) test with Chinese hamster ovary cells, the micronucleus test on bone marrow cells of mice and Chinese hamsters, and the chromosome aberration and SCE test on Chinese hamsters. In all the in vitro tests no signs of genotoxicity were detected. Whereas no in vivo mutagenicity of potassium sorbate and sodium sorbate with freshly prepared aqueous solutions and with stored potassium sorbate was found, investigations with stored sodium sorbate revealed weak clastogenic activity by increased chromosome aberrations and elevated numbers of micronuclei at doses of 200 mg/kg body weight, but no induction of SCEs.

Isolation and characterization of some products of the BHA-nitrite reaction: examination of their mutagenicity

The reaction mixture and several products arising from the reaction of butylated hydroxyanisole (BHA) and nitrite in anaerobic aqueous acidic solution were separated and tested in the Salmonella mutagenicity test. Among the nine products separable by thin-layer chromatography, 1-hydroxyl-2-tert-butyl-4-methoxy-6-nitrobenzene (BHA-NO2), tert-butyl-substituted para-quinone (t-BuQ) and 3-tert-butyl-5-methoxy-1,2-benzoquinone (t-Bu-o-Q) are dominant. The last compound has not been previously reported in this system. Spot testing indicated at least one further compound of nitroso character and traces of tert-butylhydroquinone (t-BuHQ), which reacts with nitrite to yield t-BuQ. No evidence was found for the formation of the BHA dimer under our conditions. The substances gave no evidence of mutagenicity in the Salmonella typhimurium strains TA 98 and TA 100, either in the standard plate incorporation assay or in the procedure with preincubation with or without S9 mix. In some instances the substances were unstable in the test procedure.

Genotoxic investigations of tobacco protein using microbial and mammalian test systems

Tobacco protein was assayed for mutagenicity using the Ames test and three in vivo tests. In the Salmonella strains TA 98 and TA 100 methanolic extracts of the tobacco protein and urine of rats fed tobacco protein exhibited increased revertant numbers, but extracts of feces did not. Using the micronucleus test throughout, weak mutagenic effects after feeding the tobacco protein were detected in Chinese hamsters and two inbred strains of mice, and again in Chinese hamsters when the chromosome aberration test and the SCE test were applied. The analytical specifications of the tobacco protein listed nicotine, chlorogenic acid and rutin as components. These were examined separately in a chromosome aberration test, and nicotine was discovered to be the factor or a factor responsible for the weak positive test results.

Mutagenic activity of the feces of rats following oral administration of tartrazine

After oral administration of the azo dye tartrazine, bile and feces of treated rats were investigated for mutagenicity using the Ames test with Salmonella typhimurium strains TA 98 and TA 100 with and without metabolic activation. In the presence of S 9-mix fecal extracts developed a weak but reproducible dose-related response in strain TA 100. In bile no metabolites exerting mutagenic activity were found.

Modifying action of vegetable juice on the mutagenicity of beef extract and nitrosated beef extract

The effect of juices of different vegetables on the mutagenicity of beef extract (with S-9 mix) and nitrosated beef extract (with and without S-9 mix) was examined using the Ames test. All the juices affected the induced mutagenicity of beef extract and nitrosated beef extract in the presence of S-9 mix, but not the mutagenicity of nitrosated beef extract in the absence of S-9 mix. As the vegetable juices appear to affect mutagenicity only in the presence of S-9 mix, it is concluded that the constituents of vegetables do not act directly on the mutagens; the effects are apparently caused by an interaction with the metabolic activation system.

Mutagenic activity in the stomach and small intestine of rats after oral administration of nitrosated beef extract

The products formed by the reaction of beef extract with nitrite were assayed in the Salmonella/microsome mutagenicity test. In strain TA1538, TA98 and TA100 a direct-acting mutagenic response was observed. The presence of liver-microsome preparation resulted in decreased mutagenicity. To study the absorption, distribution and excretion of mutagenic substances in nitrosated beef extract, the test material was given perorally to rats. Investigations of the stomach, bile fluid, urine, small intestine and blood samples were carried out, and mutagenicity was found in the contents of stomach and small intestine. It is supposed that unlike beef extract itself, its nitroso product is not excreted in the bile but passes directly from the stomach and small intestine.

Investigations on the detection of mutagenic activity of beef extract in rats after oral administration

After oral administration of beef extract the body fluids of Aroclor-treated and untreated rats were investigated for mutagenicity using the Salmonella/microsome test. In the stomach contents, the bile and the urine of the animals, mutagenic activity was discovered after S-9 activation. Although the mutagenic substances must have been transported by the blood stream to the excreting organs no increased mutagen-induced his+ revertants were observed in venous blood. Direct-acting mutagens were not detected in the tested body fluids, either in the Aroclor-treated rats or in the untreated ones.

Mutagenicity testing of quinine with submammalian and mammalian systems

Quinine hydrochloride was assayed for genotoxic activity by using 4 different test systems with distinct genetic endpoints. No indications for point mutations were observed in the Ames system. In 3 cytogenetic tests performed on small rodents, Chinese hamsters showed no genotoxic activity, while inbred strains of mice revealed a dose dependent increase of SCEs, enhanced incidence of micronuclei and elevated chromatid breaks.

Genotoxicity of cocoa examined by microbial and mammalian systems

Unroasted or roasted cocoa powder dispersed in water and applied to Chinese hamsters by stomach tube caused elevated numbers of SCEs in the sister-chromatid exchange test (bone-marrow cells). Roasted cocoa freed from fat produced distinctly higher SCE values with a linear dose-response relationship, whereas cocoa butter had no influence on SCE levels. Positive results in the SCE test (1.5-fold values of the controls) were obtained after application of about 5 g cocoa/kg b.w. Presumably, because of the smaller quantities that could be administered in this way, positive test results were not found when cocoa was given in the diet instead of being administered by stomach tube. Cocoa from which theobromine was extracted by chloroform did not affect SCE levels. Pure theobromine increased SCE levels in a dose-dependent way. Theobromine was also positive in the micronucleus test at 2 X 40 mg/animal and negative in the chromosome aberration test at 1 X 40 mg/animal. Cocoa and the theobromine were negative in the Salmonella/mammalian microsome mutagenicity test both with and without metabolic activation.

Chemical aspects of the mutagenic activity of the ascorbic acid autoxidation system

It has been proposed that the mutagenic activity associated with the ascorbic acid autoxidation system may involve hydrogen peroxide and peroxide radicals. We report here that the system may involve hydrogen peroxide and peroxide radicals. We report there that the mutagenic effect may also partially reside in as yet unknown secondary products. The observed mutagenicity of 2,3-diketogulonic acid, one of the main oxidation products, reflects its ability to form hydrogen peroxide.

Mutagenicity of sulphonylureas

The 11 derivatives of beta-cytotropic sulphonylureas commonly used in the treatment of diabetes mellitus were tested in vivo in the highly sensitive sister-chromatid exchange test. Chlorpropamide and tolbutamide gave a positive reaction with a clear dose-response in Chinese hamsters and mice. The two compounds gave a mutagenic response neither in the Salmonella/mammalian-microsome mutagenicity test (with and without microsomal activation) nor in the chromosomal aberration test. In the micronucleus test, chlorpropamide was positive in 3 strains of mouse, tolbutamide in one strain. In Chinese hamsters and in rats the micronucleus test was negative with both compounds.

Mutagenic evaluation of single cell protein with various mammalian test systems

Single cell protein (SCP)--a product containing 80% raw protein obtained from bacteria grown on a methanol substrate--was tested for mutagenicity in 5 in vivo tests in different mammalian species. The animals were fed either a standard laboratory diet, a semi-synthetic diet, diets containing 12.5 and 25% SCP or pure SCP. The following investigations were carried out: dominant-lethal-test; host-mediated assay; micronucleus test; chromosome studies in bone marrow cells; in vivo sister chromatid exchange test. The statistical evaluation of all test results did not reveal any evidence for mutagenic activity of the SCP.

[Identification of irradiated onions (author's transl)]

A method is described by which irradiated onions are identified by failure to root formation.

[Mutagenicity testing of irradiated laboratory animal feed in the 'host-mediated' assay with Salmonella typhimurium G 46]

Food irradiated with 10 MeV-electrons (dose: 4-5 Mrad) was tested for mutagenic effects, using the host-mediated assay. Irradiated 'Altomin' (a pelleted laboratory diet) was fed to mice for 9 to 44 days. After the 30th day of feeding, the animals additionally received irradiated glucose-solution instead of drinking water. Results did not indicate any mutagenic activity of the irradiated diet on the histidine-auxotroph strain of Salmonella typhimurium used in the assay.