Fluoranthene, a volatile mutagenic compound, present in creosote and coal tar

Creosote, a coal-tar distillation product, contains mutagens which are volatile at 37 degrees C. After distillation of creosote we found that these volatile mutagens were present in the distillation fraction with the highest boiling range (greater than 360 degrees C). The "volatile mutagenic activity" was connected with the presence of fluoranthene, a polycyclic aromatic hydrocarbon. Commercially available fluoranthene was positive in the so-called "taped-plate assay" (the test system used for the detection of volatile mutagens) towards the strains TA98 and TA100 in the presence of S9 mix. The tested creosote and coal tar contained fluoranthene in concentrations of 5.2 and 2.2%, respectively.     

Suppression of mutation induction and failure to detect mutagenic activity with Athabasca tar sand fractions

5 different histidine-requiring strains of Salmonella typhimurium were used to test the mutagenic activity of 7 different fractions of Athabasca tar-sand. None of the 7 fractions (bitumen, maltenes, asphaltenes, saturated, monoaromatic, diaromatic and polyaromatic hydrocarbons), showed positive mutagenic response in any of the Salmonella typhimurium strains. We have tested a wide range of concentrations. The results obtained so far are consistent with the lack of mutagenic activity of all investigated fractions in the absence and in the presence of metabolic activation.Assuming that there might be an association between the absence of mutagenic activity and the complexity of the tar-sand fractions, we investigated the effect of the polyaromatic hydrocaron fraction on the mutagenicity of the carcinogenic agent 2-aminoanthracene. The data obtained indicate clearly that the polyaromatic hydrocarbon fraction suppresses the mutagenic activity of 2-aminoanthracene.     

Antioxidant properties, autooxidation, and mutagenic activity of echinochrome a compared with its etherified derivative

Antioxidant properties of 2,3,5,7,8-pentahydroxy-6-ethyl-1,4-naphthoquinone (echinochrome A) were linked with the scavenging of peroxy radicals in liposomes, trapping of superoxide anion radicals, and binding of ferrous ions to inactive complexes in the aqueous phase. The antioxidant property of 6-ethyl-2,3,7-trimethoxy-5,8-dihydroxy-1,4-naphthoquinone (trimethoxyechinochrome A) was negligible. Autooxidation of echinochrome A was increased in basic media according to the degree of its dissociation. Autooxidation of polyvalent anions in basic media was accompanied by generation of naphthosemiquinone and superoxide anion radicals as free radical intermediates. An increased rate of echinochrome A autooxidation was noted in the presence of calcium ions. This was explained by a shift of pK of Ca²⁺–echinochrome A complexes toward acidic pH comparably with echinochrome A. Echinochrome A possessed pronounced mutagenic activity, while trimethoxyechinochrome A was inactive in the Salmonella/mammalian microsome reverse mutation assay (Ames test) for all examined cells (TA98, TA100, TA1537). Comparison of the chemical and biological activity of echinochrome A and trimethoxyechinochrome A demonstrated the key role of the -hydroxyl groups in the 2nd, 3rd, and 7th naphthol cycle positions. The and naphthosemiquinone radicals generated in the redox transition of 2,3-oxygroups may be the reason for the strongly pronounced mutagenicity of echinochrome A.     

Suppression of mutation induction and failure to detect mutagenic activity with athabasca tar sand fractions.

5 different histidine-requiring strains of Salmonella typhimurium were used to test the mutagenic activity of 7 different fractions of Athabasca tar-sand. None of the 7 fractions (bitumen, maltenes, asphaltenes, saturated, monoaromatic, diaromatic and polyaromatic hydrocarbons), showed positive mutagenic response in any of the Salmonella typhimurium strains. We have tested a wide range of concentrations. The results obtained so far are consistent with the lack of mutagenic activity of all investigated fractions in the absence and in the presence of metabolic activation. Assuming that there might be an association between the absence of mutagenic activity and the complexity of the tar-sand fractions, we investigated the effect of the polyaromatic hydrocaron fraction on the mutagenicity of the carcinogenic agent 2-aminoanthracene. The data obtained indicate clearly that the polyaromatic hydrocarbon fraction suppresses the mutagenic activity of 2-aminoanthracene.     

Specificity of mutagenic effect of N-nitroso-N-methylurea and relation between its mutagenic activity and carbamoylating properties

Significance of carbamoylation for mutagenic effects of N-nitroso-N-methyl-urea (NMU) on the CHO-AT3-2 cell line of Chinese hamster was studied. True point mutations occurred, due to alkylation. Carbamoylation combined with alkylation, or carbamoylation after alkylation induced the increase in other types of gene mutations as well as micro- and macroaberrations. These effects may be explained by the synergistic effect of alkylation and carbamoylation. Possible mechanisms and levels of interaction between alkylation and carbamoylation are discussed.     

The direct mutagenic activity of alpha, omega-dihalogenoalkanes in Salmonella typhimurium. Strong correlation between chemical properties and mutagenic activity

A series of 18 alpha, omega-dihalogenoalkanes (kappa(CH2)n kappa with n = 1-6 and kappa = Cl, Br, I) was tested for direct mutagenic activity in Salmonella strains TA1530, TA1535 and TA100 using spot-test procedures. The results indicate that the mutagenic behaviour of these compounds is strongly dependent upon the carbon chain length as well as the type of halogen involved. This behaviour correlates with the leaving group ability and the degree of neighbouring group participation in nucleophilic displacement reactions of the different halogen atoms.     

ω-Hydroxymodin, a major hepatic metabolite of emodin in various animals and its mutagenic activity

The hepatic microsomes derived from various animal species transformed emodin (1,3,8-trihydroxy-6-methylanthraquinone), and anthraquinoid pigment present in fungal metabolites and a constituent of plant medicines, into an unidentified anthraquinone h, along with 2-hydroxy-, 4-hydroxy- and 7-hydroxyemodins. TLC, UV, MS and NMR clarified this unidentified major metabolite as ω-hydroxy-emodin (1,3,8-trihydroxy-6-hydroxymethylanthraquinone). Among 7 animal species, the highest activity to produce this ω-hydroxyemodin was observed in the hepatic microsomes of guinea pig and rat, followed by mouse and rabbit. The microsomal activity to convert emodin into ω-hydroxyemodin was accelerated by the pretreatment of animals with phenobarbital, and inhibited by SKF 525A. The microsomal hydroxylation reactions of the methyl residue and the anthraquinoid nucleus of emodin were presumed to be catalyzed regiospecifically by multiple forms of cytochrome P-450.

ω-Hydroxyemodin was not mutagenic to Salmonella typhimurium in the absence of S9, but exhibited mutagenicity in the presence of an activating system. This genotoxic potential was comparable to 2-hydroxyemodin, a direct-acting mutagen.     

Uptake, metabolism and mutagenic activity of aromatic glycidyl compounds

Aromatic diglycidyl compounds are very active mutagens when assayed in in vitro tests. In vivo, however, resorcinol diglycidyl ether provided no evidence for the clastogenic activity, while diglycidylaniline exhibited definite mutagenic activity in the micronucleus test. Since the only difference between these two compounds lies in the binding mode of the glycidyl groups to the aromatic nucleus (i.e. ether oxygen vs. aminic nitrogen), this apparent discrepancy in mutagenic activity led to the question of the mechanisms involved in such an activity difference. Although no clear signs of differential uptake or excretion could be detected in mice, differences could be seen in the spectrum of urinary metabolites; while resorcinol diglycidyl ether seemed to become fully converted to the genetically inactive bis-diol compound, a sizeable proportion of diglycidylaniline was converted only to the diol-epoxide. In vitro investigations and enzyme kinetic measurements with postmitochondrial supernatant of rat or mouse liver homogenate (S-9) finally yielded the biochemical explanation for this behaviour, as they showed a very low affinity of the diol-epoxide metabolite of diglycidylaniline for the epoxide hydrolase, normally involved in the degradation of such compounds. The diol-epoxide obtained from resorcinol diglycidyl ether, on the other hand, has an affinity to the degradation enzyme similar to, or even higher than, the one measured with the parent substance.     

Simultaneous measurement of toxicity and mutagenic activity

The assay of mutagenic activity of toxic drugs is difficult to perform and analyze, because one needs to know the kinetics of both effects in order to draw reliable conclusions. This is the case with niflumic acid (NA), which reduced the viability of S. typhimurium TA1535 100 times in the Ames test, but the background microcolonies show no difference from controls and the number of revertants was not altered by the drug. A test which measures the kinetics of growth of viable bacteria and mutants in liquid medium has been developed and applied to NA. No mutagenic activity was detected and elimination of the toxicity from the medium is suggested.     

The mutagenic activity and structure of pesticides

The data on mutagenicity of pesticides as to their chemical structure are summarized and discussed. The results from investigation of cytogenetic action of 55 pesticides and their metabolites in somatic human and animal cells are presented. Some structure fragments of molecule related to genotoxic effects are selected.     

Study of the DNA-damaging activity of the mutagenic derivative of tetrahydrodiazapyrene, DDDTDP

2,7-diamino-4,9-dioxo-5,10-dioxy-4,5,9,10-tetrahydro-4.9--diaza prein (DDDTDP)--the frameshift mutagen--induced frameshift mutations in indicator strain Salmonella typhimurium. The mutagen displays strong DNA damaging activity in murine L cell line. The DNA was analyzed for single strand breaks by alkaline elution assay. Analysis of reparation of DNA breaks suggests that DDDTDP acts as bifunctional agent.     

The organic solvents acetone, ethanol and dimethylformamide potentiate the mutagenic activity of N-methyl-N'-nitro-N-nitrosoguanidine, but have no effect on the mutagenic potential of N-methyl-N-nitrosourea

The frequency of recessive chlorophyll and embryonic lethals included by N-methyl-N'-nitro-N-nitrosoguanidine (MNNG) in Arabidopsis thaliana was markedly increased when exposure of the seeds to MNNG (3 h) was carried out in the presence of 4-12% acetone, 4-16% ethanol or 8-32% dimethylformamide. The enhancement of MNNG mutagenicity was proportional to the concentrations of these organic solvents. In contrast, neither of them, applied at the same conditions and doses, influenced the mutagenic activity of N-methyl-N-nitrosourea. The solvents without mutagens did not influence the spontaneous rate of mutations and revealed no or very weak toxic effect as measured by the seed germination.     

Investigation of the mutagenic activity of tobacco smoke

The genotoxic effect of whole tobacco smoke was studied employing the Salmonella/microsome mutagenicity assay, the micronucleus test in mouse bone marrow and UDS in peripheral human lymphocytes. It was established that tobacco smoke (120-480 cm3 in a 16-1 glass chamber, at 1-10 min exposure time) induced a 3-9-fold increase of spontaneous his+ reversion mutation rate in S. typhimurium TA98, but not in strains TA97a, TA100 and TA102. Addition of S9 mix obtained from the liver of Aroclor 1254-treated rats was necessary to reveal the mutagenic activity of tobacco smoke. Treatment of BDF1 mice placed in a 14-1 glass chamber with tobacco smoke (600 cm3 smoke, 2 exposures of 30 min each, with a 1-min interval between them) caused a 2-fold dose-dependent elevation of the number of micronucleated PCE in bone marrow. No cumulative effect was detected when mice were treated with tobacco smoke during 2-28 consecutive days. The effect observed 24 h after tobacco-smoke exposure was abolished 48 h later. Tobacco smoke (180 or 360 cm3) passed through the culture medium (with or without S9 mix) of human peripheral lymphocytes (the cells were then incubated for 60 min at 37 degrees C) did not increase the spontaneous rate of UDS. Both the Salmonella/microsome mutagenicity assay employing S. typhimurium TA98 strain and the micronucleus test in mouse bone marrow might be useful in studying tobacco smoke-induced mutagenesis.     

The mutagenic activity of sodium perborate

Sodium perborate (CAS No. 1333-73-9, 10486-00-7, or 13517-20-9, depending on the structural formula given) is produced in huge amounts mainly for its use as a bleaching agent in laundry detergents. Its action involves the liberation of active oxygen species at elevated temperatures. In view of the widespread use of this compound it is surprising to note that no mutagenicity test data yet exist. The investigations reported in this paper have shown that sodium perborate is indeed capable of producing mutagenic changes in a number of in vitro test systems. Its potential for inflicting damage to DNA could be demonstrated in an assay which is tailored to probe for oxidative damage induced by a chemical agent. As expected, sodium perborate proved to be able to oxidize thymidine to an appreciable extent at an incubation temperature of 80 degrees C, but even at 40 degrees C thymidine oxidation was measurable. The compound induced point mutations in the Salmonella typhimurium strains TA100 and TA102, while TA98 did not respond. Also, incubation in the presence of a mammalian auxiliary metabolic system (rat liver S9) abolished the mutagenic activity completely. Finally, Chinese hamster ovary cells (strain CHO-K1) were shown to undergo extensive chromosomal damage when treated with sodium perborate. The rather unusual prevalence of chromosome rearrangements was especially noted. Sodium perborate is thus to be regarded as a direct-acting in vitro mutagen.     

The mutagenic activity of gastric juice

The mutagenic activity of fasting gastric juice was assessed in 123 patients including 18 with normal endoscopic findings, 53 peptic ulceration, 9 gastric cancer, 12 pernicious anaemia and 31 patients who had undergone peptic ulcer surgery in the past. Significant mutagenic activity was detected in 96 (78%). Marked variations in mutagenic activity were noted both within and between the patient groups and no significant differences were detected. No correlation was found between mutagenic activity and patient age or sex, gastric pH, bile acid concentrations or bacterial counts, intestinal metaplasia on gastric mucosal biopsy, or intragastric nitrite. About 30% of gastric juice samples showed evidence of a cytotoxic activity towards the Salmonella tester strains in the mutation assay. Preliminary studies on other body fluids showed the presence of significant mutagenic activity in fasting saliva, bile and plasma. These findings demonstrate widespread human exposure to potentially genotoxic substances.     

Genotoxic and mutagenic activity of environmental air samples in Flanders, Belgium

Atmospheric pollution is assumed to play a role in the incidence of respiratory diseases and cancers. Airborne particles are able to penetrate deep into the lung and are composed of complex chemical mixtures, including mutagens and carcinogens such as polycyclic aromatic compounds (PACs). The present study reports mutagenic and genotoxic activities associated with ambient air collected near a busy street in Borgerhout, at an industrial site in Hoboken and in Peer, a rural community 70 km east of Antwerp in Flanders, Belgium. Airborne particulates (PM10) and semi-volatile organic compounds were sampled during winter and summer. Samples were collected with a high-volume sampler using quartz filters (QF) and polyurethane foam (PUF) cartridges. The mutagenic and genotoxic activity of the organic extracts was determined using the Salmonella test/standard plate-incorporation assay and the Vitotox assay. Concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in the extracts were determined by reversed-phase high-performance liquid chromatography (HPLC). The mutagenicity assay, using Salmonella typhimurium strain TA98, demonstrated direct mutagenicity of up to 58 revertants/m3 for the QF extracts and low or no mutagenic activity in the PUF extracts. Metabolic activation of the samples resulted in high indirect mutagenicity for both QF and PUF extracts: up to 96 revertants/m3 were found in QF samples and 62 revertants/m3 in PUF samples. Genotoxic effects of the filter extracts were assessed with the Vitotox assay: some direct genotoxic effects were noted, i.e. without metabolic activation, but almost no effects were observed after metabolic activation. Without activation, most PUF extracts were bacteriotoxic. With metabolic activation this toxicity disappeared, but genotoxic effects were not observed. Statistical analysis showed that the observed biological effects correlated well with the PAH concentrations.     

Change in mutagenic activity of genistein after a nitrite treatment

This study examined the mutagenic activity of genistein after a nitrite treatment under acidic conditions. Nitrite-treated genistein exhibited mutagenic activity toward Salmonella typhimurium strains TA 100 and TA 98 with or without S9 mix. Nitrite-treated genistein was demonstrated by electron spin resonance to generate radicals. An instrumental analysis showed 3'-nitro-genistein to have been formed in the reaction mixture. However, 3'-nitro-genistein did not exhibit mutagenic activity toward the S. typhimurium strains, suggesting that other mutagens might also have been formed in the reaction mixture. The clastogenic properties of nitrite-treated genistein and 3'-nitro-genistein were examined by a micronucleus test with male ICR mice. Nitrite-treated genistein and 3'-nitro-genistein showed a significantly higher frequency of micronucleated reticulocytes in mice than in the control group. These results suggest that a daily oral intake of genistein and nitrite through foodstuffs might induce the formation of various mutagenic compounds in the body.     

The distribution of mutagenic activity in red, rose and white wines

Using a modified Salmonella typhimurium TA98 Ames-test system, more than 150 red, white and rose wines were analyzed for direct-acting and microsomal enzyme-enhanced mutagenic activity. The following conclusions were reached from analysis of this wine mutagenicity data base. White and rose wines, as well as grape juices, exhibited little or no detectable direct-acting or microsomal enzyme-enhanced mutagenic activity. However, red wine samples contained highly variable amounts of mutagens, ranging from undetectable to levels 30-fold above the sensitivity limit of the assay system. The variations in red wine mutagenicity were unrelated to grape variety, vintage, aging methods or production region. Hence, individual winery production practices must represent the most significant contribution to the variations observed.