Genotoxicity of 2-halocinnamaldehydes in two bacterial assays. Induction of SOS repair and frame-shift mutation

2-Chlorocinnamaldehyde and 2-bromocinnamaldehyde, compoundsof practical interest, for example, as bacterioddes and fungicidesor for utilization in light sensitive layers, were tested inthe Ames preincubation test with various Salmonella typhimuriumstrains, and in the SOS chromotest with Escherichia coli PQ37. 2-Chlorocinnamaldehyde was clearly mutagenic in strain TA100 (6081 revertants/µmol) and in strain TA 98 (3050 revertants/µmol)without S9 mix, and was clearly positive in the SOS chromotest(SOSIP = 0.181). 2-Bromocinnamaldehyde was a strong mutagenin strain TA 100 (105, 500 revertants/µmol), in strainTA98 (41567 revertants/µmol) and in strain TA 1538 (15825revertants/ µmol), and also unambiguously mutagenic instrain TA 1535 (2110 revertants/µmol) without S9 mix.The SOSIP in the SOS chromotest was 1.5. Addition of S9 mixled to a marked decrease in the mutagenic activity of 2-bromocinnamaldehydein all strains tested. In the case of strain TA 1535, mutagenicactivity was abolished or not significant in the presence ofS9 mix. The possible primary mechanisms underlying these mutageniceffects are discussed. Frame-shift activity of these halocinnamaldehydescan be explained by their planar structure. ¹To whom correspondence should be addressed     

Comparative genotoxicity of halogenated acetic acids found in drinking water

Three short-term assays (SOS chromotest, Ames fluctuation testand newt micronucleus test) were performed to detect the genotoxicactivity of organohalides, compounds likely to be found in chlorinatedand/or ozonated drinking water: monochloro-, dichloro- and trichloroaceticacids and monobromo-, dibromo- and tribromoacetic acids. Withthe SOS chromotest, only three of the chemicals studied (dichloroaceticacid, dibromo- and tribromoacetic acids) were found to induceprimary DNA damage in Escherichia coli PQ 37. In the Ames fluctuationtest, all the compounds except monochloroacetic acid showedmutagenic activity in Salmonella typhimurium strain TA100. Inthese two in vitro tests, a good correlation between increasingnumber of substituents and decreasing mutagenicity was observed.Namely, the toxicity of brominated and chlorinated acetic acidsdecreased when the number of substituents increased. The newtmicronucleus test detected a weak clastogenic effect on theperipheral blood erythrocytes of Pleurodeles waltl larvae fortrichloroacetic acid only. ³To whom correspondence should be addressed at: Institut Pasteur de Lille, Laboratoire de Toxicologie Génétique, 1 Rue du Professeur Calmette, BP 245, 59019 Lille Cedex, France     

Use of the SOS chromotest, the Ames-fluctuation test and the newt micronucleus test to study the genotoxicity of four trihalomethanes

Three short-term assays (the SOS chromotest, the Ames-fluctuationtest and the newt micronucleus test) were carried out to evaluatethe genotoxicity of four trihalomethanes (chloroform, bromodichloromethane,chlorodibromomethane and bromoform). With the SOS chromotest,all the chemicals studied except chloroform were found to induceprimary DNA damage in Escherichia coli PQ37. In the Ames-fluctuationtest, only bromoform showed mutagenic activity on Salmonellatyphimurium strain TA100. The newt micronucleus assay detecteda clastogenic effect on the peripheral blood erythrocytes ofPleurodeles waltl larvae for bromodichloromethane and bromoform.It appeared that the presence of bromine substituent(s) generallyled to significant genotoxic activity. Moreover, the use ofthe metabolic system significantly increased the genotoxicityof the brominated trihalomethanes in the SOS chromotest. Unlikeprevious investigations in which the SOS chromotest was alwaysthe least interesting assay, this study exhibited the good efficiencyof this in vitro test on E.coli for the detection of trihalomethaneswith bromine substituents. ⁴To whom correspondence should be addressed at: Institut Pasteur de Lille, Laboratoire de Toxicologie génétique, 1 rue du Professeur Calmette, BP 245, 59019 Lille Cedex, France     

Genotoxicity of p-nitrocinnamaldehyde and related alpha, beta-unsaturated carbonyl compounds in two bacterial assays

Seventeen cinnamaldehydes, cinnamic acids, 2-furylacroleins and related compounds were tested in the Salmonella preincubation reversion assay and in the SOS chromotest. Of eight compounds containing nitrogroups, seven were clearly mutagenic in the presence of S9 mix and six in its absence; whereas none of the parent compounds not containing a nitrogroup and none of the congeners containing chlorine, methoxy or amino groups were mutagenic. Metabolic epoxidation was excluded in additional experiments using SKF525, an inhibitor of mono-oxygenases, and trichloropropene oxide, an inhibitor of epoxide hydrolases. Less or no mutagenicity was found in the nitroreductase deficient strains Salmonella typhimurium TA100NR or TA98NR and in the O-acetyltransferase deficient strains TA100/1,8-DNP6 or TA98/1,8-DNP6 except with 5-nitro-2-furylacrolein which exhibited decreased mutagenicity in TA100NR when compared with TA100 but the highest mutagenicity in TA100/1,8-DNP6. Less or no genotoxic activity was found in the SOS chromotest when using the nitroreductase deficient Escherichia coli strain PQ253 whereas all seven compounds tested were positive in strain PQ37. The results demonstrate the importance of the nitro group and that the compounds are activated either by bacterial nitroreductase or by the nitroreductase in the S9 mix. A chemical activation of the acrolein moiety by the negative inductive effect of the nitro group is unlikely. The genotoxicity of the cinnamyl compounds is dependent on the position of the nitro group in the phenyl ring. The genotoxicities of the p-nitro compounds were about two orders of magnitude higher than those of the ortho and meta congeners. The comparison between the Ames test and the SOS chromotest showed good agreement.     

Genotoxic activities of 2-nitronaphthofurans and related molecules

The genotoxic activities of 63, 2-nitronaphthofurans and relatedmolecules were examined using two bacterial short-term tests,the Salmonella mammalian microsome assay test or Mutatest, amutagenesis assay, and/or the SOS Chromotest, an assay for inductionof an SOS function in Escherichia coli. Seven compounds werealso investigated in the Chinese hamster ovary cells/hypoxanthine— guanine phosphoribosyl transferase (CHO/HGPRT) test,a mammalian gene mutation assay. Our main conclusions are thefollowing: (a) Simple empirical rules relating structure tomutagenic activity in the Mutatest can be derived for some ofthe compounds. In particular, they account for the extremelyhigh Mutagenic Potency of 7-methoxy-l-methyl-2-nitronaphtho[2,1-b]furan(R7372), {small tilde}2 x 10⁶ mutants/nmol on strain TA100.(b) There is a good quantitative correlation between the MutagenicPotency in the Salmonella/mammalian microsomes assay and theSOS-inducing potency in the SOS Chromotest. This, and previousevidence, suggests strongly that the 2-nitronaphthofurans derivativesare essentially recA and thus probably umuDC-dependent mutagens.(c) Four out of seven compounds tested hi the CHO/HGPRT assaygave responses correlated with the bacterial responses. Oneof them, 7-methoxy-2-nitronaphtho[2,1-b]furan (R7000), is among,or is, the strongest mutagen described for mammalian cells.We briefly discuss the practical and theoretical implicationsof these results. ³To whom correspondence should be addressed     

Induction of SOS repair by monofunctional methanesulphonates in various Escherichia coli strains. Structure-activity relationships in comparison with mutagenicity in Salmonella typhimurium

Seventeen monofunctional alkylmethanesulphonates of widely varyingstructures were investigated in the SOS Chromotest using theEscherichia coli strains PM21, PQ37 and GC4798. As a measureof the SOS-inducing activity, the ß-ga1actosidaseenzyme units (Up/µmol) were determined. Strains PM21 andPQ37 gave similar results in spite of the presence of differentgenetic markers. In general, the S_N1 type secondary compounds(O-alkylation) induced higher SOS repair than the S_N2 type primarycompounds (N-alkylation). However, methylmethanesuiphonate exertedthe highest SOS induction of all tested strains, presumablydue to its extremely high S_N2 reactivity. In general, strainGC4798, which lacks 3-alkyladenine-DNA glycosylases I and II,was more sensitive towards monofunctional alkylating compoundsand in particular towards the S_N2 type compounds. A good correlationwas found between the SOS repair response in the E.coli strainsPM21 and PQ37 and the mutagenicity in Salmonella lyphimuriumTA100. There was, however, little correspondence when comparingthe two measures used for the SOS-inducing activity in thiswork, the SOSIP (SOS-inducing potency) and the specific ß-galactosidaseactivity (Up/µmol). This effect was explained by the differenttoxicity corrections used for the calculation of the two measures.Whereas for the SOSIP value the single constitutive enzyme alkalinephosphatase is used, for the Up/µmol the absorbance at600 nm, which indicates the growth delay (overall toxicity),is utilized. The influence of the toxicity corrections is discussedin more detail. ¹To whom correspondence should be addressed     

SOS induction by {gamma}-radiation in Escherichia coli strains defective in repair and/or recombination mechanisms

Ionizing radiation causes several types of DNA lesions, mainlysingle- or double-strand breaks and base damage. By means ofthe chromotest, an assay that allows the level of the SOS responseto be monitored via ß-galactosidase enzymatic activity,the roles of several repair (uvrA, recN and oxyR) and recombination(recB, recJ and recO) genes in the response of Escherichiacolito     

Testing human faecal extracts for genotoxic activity with the SOS Chromotest: the importance of controlling for faecal enzyme activity

Two aqueous extracts of human faeces were prepared from a healthymale donor and assayed in the SOS Chromotest. Both extractswere positive in microtitre fluctuation tests in Salmonellatyphimurium TA100 and Escherichia coli WP2uvrA(pKM101). Differenceswere observed in the induction factors of these samples whenp-nitrophenyl-/5–D-galacto-pyranoskle (p-NPG) and o-nhTophenyl–3-D-galactopyranoside(o-NPG) were used as substrates for the /3-galactosidase assayin the SOS Chromotest. With one sample, a positive inductionfactor was reproducibly obtained using p-NPG but not o-NPG.When the bacterial cells were washed with fresh LB broth beforeenzyme assay, the positive induction factor obtained with p-NPGwas reduced to an insignificant level. During the 2-h treatmentperiod, both faecal samples enhanced bacterial growth abovethat of the zero-dose control. When SOS Chromotest assays wereperformed with no bacteria or with 5. typhimurium TA100 or hisG46(non-lactose fermenting organisms) in place of E. coli PQ37,it was found that the extracts contained significant levelsof endogenous 3–galactosidase and alkaline phosphatase,which, due to their carry-over in the bacterial pellet (aftercentrifugation to remove the coloured extract) gave rise tothe positive induction factor obtained with p-NPG. The resultsobtained in these experiments indicate that where the SOS Chromotestis applied to biological samples, care should be taken in theinterpretation of the data and that a washing step should beincluded to prevent possible errors occurring due to exogenousenzymes in the sample.     

Mutagenic activity in synthetic pyrethroids in Salmonella typhimurium

Four pyrethroids, allethrin, resmethrin, permethrin and fen-valerate,were tested for mutagenicity in bacterial reversion assay systemswith seven strains (TA1535, TA100, TA1538, TA98, TA1537, TA97and TA104) of Salmonella typhimurium. Our results show thatthree pyrethroids, namely resmethrin, permethrin and fenvalerate,were not found to be mutagenic in S. typhimurium in the presenceor absence of a rat liver activation system. Allethrin was foundto be mutagenic with TA100, TA104 and TA97 strains and requiredmetabolic activation (S9 mix) in order to show its activity,mainly with TA100 and TA104 strains.     

Genotoxidty of 2-nitropropane and 1-nitropropane in Salmonella typhimurium and human lymphocytes

A 10- and 12-fold increase of revertant numbers could be demonstratedfor 2-nitropropane (2-NP of >99% purity) tested in the preincubationassay with Salmonella typhimurium strains TA 100 and TA 98 inthe presence and absence of s9 mix. In the nitroreductase-deficientstrains TA 100NR and TA 98NR, 2-NP was less mutagenic than inthe parent strains. In human lymphocytes the induction of aweak clastogenic effect and of sister chromatid exchanges requiredexogenous metabolic activation. No significant mutagenic orcytogenetic response was found with 1-nitropropane of 97% purityin S.typhimurium or human lymphocytes.     

Applicability of the SOS Chromotest to detect urinary mutagenicity caused by smoking

The mutagenicity of urine obtained from five cigarette smokerswas investigated using two bacterial assays: the Ames test andthe SOS Chromotest. Urinary mutagens were extracted on AmberliteXAD-2 resin. Four urine samples showed activity towards Salmonellatyphimurium tester strain TA98 with S9 mix while no SOS-inducingactivity could be measured with Escherichia coli strain PQ37in the SOS Chromotest. Using factorial design and a positivecontrol benzo[a]pyrene (BaP), the concentration of S9, nicotinamideadenine dinucleotide phosphate (NADP) and glucose-6-phosphate(G6P) were optimized (2% 0.5 mM and 10 mM respectively) forthe SOS Chromotest. The SOS-inducing power of BaP was 1.42/nMwith the standard S9 mix and 3.26/nM with the optimized S9 mix.B buffer and the age of L-broth were found to decrease the sensitivityof ß-galactosidase assays in the SOS Chromotest. A4000-fold urine concentrate from a smoker was finally testedusing the Ames test and the modified SOS Chromotest. Mutagenicand toxic activities were found toward tester strain TA98 (+S9mix) in the Ames test but no inducing activity was detectedwith strain PQ37 (+S9 mix) showing that the SOS Chromotest isnot at present suitable for assaying urinary mutagens in thepresence of an in vitro metabolic activating mixture.     

Comparative mutagenicity of structurally related aliphatic epoxides in a modified Salmonella/microsome assay

Four structurally related aliphatic epoxides (1,2-epoxypropane,1,2-epoxyisobutane, cis- and trans-2,3-epoxybutane) have beentested in the Salmonella/microsome assay, modified for volatilesubtances, using the strains TA1535 and TA100. The aim of thestudy was to evaluate the effect of methylation on the mutagenicityof 1,2-epoxypropane in this vaporization assay, with and withoutexogenous metabolization. All substances induced a significantincrease of revertants in the strains TA1535 and TA100. In termsof mutagenic potency, the following hierarchy was observed inthe standard tester strain TA1535 and in the absence of ratS9: 1,2-epoxypropane > cis-2,3-epoxybutane > 1,2-epoxyisobutane> trans-2,3-epoxybutane. After exogenous metabolization,the mutagenic response of 1,2-epoxyisobutane was substantiallyreduced, while a moderate decrease of cis-2,3-epoxybutane wasobserved in the presence of S9, as compared with the responsewithout S9. No influence of the S9 on the mutagenic responseof trans-2,3-epoxybutane was noticed in both strains TA1535and TA100, while an increased response with 1,2-epoxypropanewas observed in TA100 but not in TA1535. The results suggestthat the vaporization assay may provide more relevant informationconcerning mutagenic potencies of gaseous or volatile compoundsthan the common treat-and-plate or preincubation assays. Moreover,it appears that mutagenicity theories, based only upon inductiveeffects of side groups, may not suffice to explain differencesin mutagenicity. Sterical factors or differential interactionswith metabolizing enzymes could also be important in the evaluationof mutagenic effects. ⁴Present address: Ministrium für Umwelt und Gesundheit,Kaiser Friedrichstrasse 7, D-6500 Mainz, Germany      

Bacterial genotoxicity of nitrosated famotidine

Famotidine, a histamine H2-receptor antagonist, was devoid ofmutagenic activity in seven his^- Salmonella typhimurium strains(TA1535, TA1537, TA1538, TA97, TA98, TA100 and TA102) and wasequitoxic in repair-proficient (WP2) and repair-deficient (WP2uvr,WP67, CM561, CM571, WP100 and CM871) Escherichia coli strains,both in the presence and in the absence of S9 mix containingliver S9 fractions from Aroclor-treated rats. However, aftera short pre-incubation step with nitrite in an acidic environment,the drug increased, by a direct mechanism, the number of his⁺revertants in Salmonella strains TA100, TA102 and TA97 (a decreaseof mutagenicity being conversely observed in TA1535) and oftrp+ revertants in E. coli strains WPluvrA and WP67. Moreover,it enhanced the induction of non-reparable DNA damage in E.coli strains simultaneously lacking the uvrA-dependent excisionrepair and the lexA post-replication repair pathways. The mutagenicityof acidified nitrite-famotidine mixtures was related to dosesof both precursors, with a maximum production of mutagenic derivativesin a slight molar excess of nitrite. The optimal pH of the nitrosationreaction (2.0) was intermediate between the one required forcimetidine (1.5) and ranitidine (2.5). Potency of famotidineas a precursor of mutagenic derivatives was considerably lowerthan the one of the other two H₂ blockers. The nitrosation productsof all three drugs mainly induced base-pair substitutions inSalmonella DNA, to a greater extent at sites containing G-Cbase pairs (strain TA100) in the case of famotidine and cimetidine,and at sites containing AT base pairs (TA102) in the case ofranitidine. Although these experimental findings may suggestpossible toxicological consequences in ulcer patients receivinganti-secretory drugs, various considerations tend to minimizetheir practical in vivo relevance, especially for risk-benefitevaluations. Additionally, as in the case of cimetidine andranitidine, formation of mutagenic nitrosated famotidine wasefficiently prevented by equimolar ascorbic acid.     

9-Methoxytariacuripyrone, a naturally occurring nitro-aromatic compound with strong mutagenicity in Salmonella typhimurium

9-Methoxytariacuripyrone, a nitro-aromatic compound isolatedfrom Aristolochia brevipesshowed strong mutagenic activity instrain TA98, TA100 and some YG strains of Salmonella typhimuriumwithand without S9 mix. Incubation with cytosol resulted in a heavyincrease in mutagenicity. When incubated with microsomes theactivity was dramatically decreased. The results are discussedin view of the enzymes possibly involved in activation and detoxificationof the compound. The role of the basic structure on the mutagenicitymediated through the nitro group was also considered.     

Genetic differences between the standard Ames tester strains TA100 and TA98

The standard Ames tester strains of Salmonella typhimurium areseparated by many steps in their pedigree, some involving mutagentreatments, and contain independently isolated uvrB-bio-galdeletions and rfa mutations. In this work the araD531 mutationwas introduced into the Ames tester strains TA100 and TA98.The responsiveness of the resulting strains (BA15 and BA14)to a number of chemical mutagens was then assessed by monitoringthe induction of forward mutations to L-arabinose resistance(Ara test). Here we have shown that these two strains of theAmes test differ greatly in their responses to mutagens, inways that are not associated with the mutagenic specificitiesof the original his mutations. In general, the genetic backgroundof strain TA100 appears to be more sensitive to the killingeffects of chemicals than that of TA98. The greatest differenceswere found with nifurtimox (NFX) and its analogue, compound1K. The Ara test responded to the mutagenic effects of thesetwo nitrofurans when carried out in the genetic background ofstrain TA98 but not in that of TA100. A higher sensitivity tothe lethal effects of NFX and 1K together with the greater nitroreductioncapability of strain TA100 as compared with TA98 might explainthe differences. In conclusion, our results indicate that thestandard Ames S. typhimurium tester strains are not isogenicand that genetic differences at loci other than his might besignificant for mutagenicity testing. To this respect the routineuse of the isogenic set of S. typhimurium strains constructedby Popkin et al. (Mut. Res., 224, 453–464, 1989) and derivedfrom strain hisD3052 (as the standard TA98) seems advisable.     

Specificity of base substitution mutations induced by the dietary carcinogens 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP) and 2-amino-3-methylimidazo[4,5-f]quinoline (IQ) in Salmonella

The base pair substitution mutational profiles induced by the heterocyclic amine cooked food mutagens PhIP and IQ in Salmonella typhimurium strains TA100 and TA1535 were determined by colony hybridization analysis. Both PhIP and IQ induced predominantly G→TA transversions in strain TA100 (rfa,ΔuvrB/pKM101) with a pronounced preference for the second codon position (CC→CAC; 72% of total). PhIP also reverted strain TA1535 (rfa, ΔuvrB) efficiently at concentrations similar to those required for strain TA100. In contrast to the PhIP-induced mutational profile observed in strain TA100, in strain TA1535 PhIP induced exclusively G→AT transitions at the second codon position (CC→CTC; 96–99% of total). Base substitution mutagenesis induced by heterocyclic amines related to PhIP is generally SOS-dependent, requiring the presence of plasmid pKM101 in Salmonella hisG46 strains. Thus, the SOS dependent reversion of S. typhimurium strain TA100 probably reflects error-prone lesion bypass at the major PhIP- guanosine adduct at the C-8 position. The G→AT transition mutations induced by PhIP in strain TA1535 appear to be SOS-independent, however, suggesting that these mutations may arise from the formation of PhIP-DNA adducts other than the replication-blocking C8-dG lesion. Environ. Mol. Mutagen. 31:327–332, 1998 © 1998 Wiley-Liss, Inc.     

Formaldehyde is a bacterial mutagen in a range of Salmonella and Escherichia indicator strains

Formaldehyde was examined for bacterial mutagenicity using Escherichiacoli WP2(pKM101) and WP2uvrA(pKM101), and Salmonella typhimuriumTA1535, TA1537, TA1538, TA98, TA100 and TA102, in the absenceof any exogenous source of metabolic activation. Using pre-incubationexposure, clear mutagenicity was seen for TA98, TA100 and TA102,and both E.coli strains. In standard plate-incorporation assays,consistent mutagenicity was seen only for TA100 and WP2uvrA(pKM101).No evidence of mutagenicity was seen for TA1535, TA1537 or TA1538using either method of exposure. These data confirm the enhancedability of the pre-incubation method to detect the mutagenicityof formaldehyde both quantitatively, as expressed by numbersof revertant colonies, and qualitatively, in terms of the rangeof indicator strains reverted. The relatively greater sensitivityof the pre-incubation assay is probably due to better containmentof a volatile agent and/or lack of interaction with agar duringthe initial period of exposure. The findings are consistentwith the suggestion that formaldehyde induces lesions in bacteriawhich are, at least to some extent, excision-repairable, andindicate that the presence of the R-factor plasmid may be requiredfor the expression of its mutagenicity in excision repair-deficientSalmonella.     

Relevance of plasmid pKM101-mediated mutagenicity in bacteria to genotoxicity in mammalian cells

Three structurally related compounds, 4-acetoxy-3-acetoxy-methyl-acetophenone(AAMAP), 1-[4'- hydroxy-3'-hydroxy-methylphenyl]-2-[benzyl-t-butylamino]ethanone hydrochloride (HHBEH) and 1-[4'-hydroxy-3'-hydroxymethyl-phenyl]-2-[benzyl-t-butylamino]ethanol (HHBE), gave positive dose-related mutagenic responsesin the Ames test when Salmonella typhimurium strain TA100 wasused as the test organism. Strain TA100 carries the hisG46 allele,which is revertable by base changes, together with plasmid pKM101,which encodes mucAB genes that are analogous to umuDC, the chromosomalSOS-repair genes of Escherichia coli K-12. None of the compoundswas mutagenic in Ames strain TA1535, which is the plasmid-freederivative of strain TA100. Only AAMAP, and that at only thehighest concentration tested, was mutagenic in strain TA98,which detects frameshift mutations and carries plasmid pKM101.No compound was significantly mutagenic in strain TA1538, whichis the plasmid-free derivative of strain TA98. When the threecompounds were tested for the induction of sister-chromatidexchanges (SCEs) in Chinese hamster cells, the two more potentmutagens, AAMAP and HHBEH were found to increase SCEs, whereasHHBE did not give a significant response at any concentrationtested. Ames test data showing plasmid pKM101-dependent mutagenesisare therefore, at least for these compounds, relevant indicatorsof eukaryotic genotoxicity. Parts of this paper were communicated to the Science Group atthe 123rd British Pharmaceutical Conference, Jersey, 1986.      

Mutagenic evaluation of some triazino indoles using the Salmonella/mammalian microsome assay

The mutagenicity of ethyl l,2,3-triazino[5,4-b]indole-4-carb-oxylateN(3)-oxide (D3) and 2-chloroethyl 1,2,3-triazino-[5,4-b]indole-4-carboxylateN(3)-oxide (D4), heads of series of new products with considerableplatelet antiaggregating and hypotensive activity, and theirprecursors 2-ethoxy-carbonylmethyl-l-methyUndole-3-carboxylicacid (A₃) and 2-(2-chloroethoxycarbonyhnethyl)-l-methylindole-3-carb-oxylkacid (A₄) were tested in four strains of Salmonella typhimurium(TA98, TA100, TA97 and TA102) using the standard plate incorporationtechnique. A₃ and A₄ were not mutagenic whereas D3 was mutagenicto all the strains and D₄ was mutagenic to TA97, TA98 and TA100.The addition of 4 or 10% of S9 mix decreased the mutagenic activityof both compounds. This effect was independent of the concentrationof S9 in the S9 mix.     

The effectiveness of Salmonella strains TA100, TA102 and TA104 for detecting mutagenicity of some aldehydes and peroxides

Several aldehydes and peroxides were tested for mutagenicityusing Salmonella typhimurium tester strains TA97a, TA100, TA102and TA104, in the presence and absence of Aroclor-induced liverS9 mix from F344 rats and B6C3F₁ mice, in either preincubationor vapour phase rotocols. Some chemicals were tested in additionalSalmonella strains. Benzaldehyde, butyraldehyde, benzoyl peroxide,4-chlorobenzaldehyde, isobutyraldehyde, propionaldehyde andveratraldehyde were non-mutagenic Acetaldehyde and dicumyl peroxidegave inconsistent results and furfural gave equivocal responsesin TA100 and TA104. Cumene hydroperoxide, formaldehyde and glutaraldehydewere mutagenic in TA100, TA102 and TA104. trans-Cinnamaldehydeexhibited a weak mutagenic response in TA100 with mouse liverS9 only. 2,4,5-Trimethoxybenzaldehyde was mutagenic only instrain TA1538 with rat liver S9. With the exception of butanoneperoxide, which was mutagenic only in TA104, all chemicals mutagenicin strains TA102 and/or TA104 were also mutagenic in TA100.The data do not, therefore, support the preferential use ofstrains TA102 and TA104 for screening aldehydes and peroxidesfor mutagenicity. For a number of these chemicals the advantagesof using TA102 or TA104 was in the increased responses comparedwith those obtained with TA100. Two of the four peroxides weremutagenic and one of these was mutagenic only with TA104. Thissuggests that strains TA102 and TA104 be used if peroxides arenot mutagemc in TA100 or TA97. ⁴Present addresses: ⁴British American Tobacco Ltd, SouthamptonSO15 8TL, UK ⁵FRAME, Nottingham NG1 4EE, UK ³To whom correspondence should be addressed. Tel: +1 919 541 4482; Fax: +1 919 541 2242; Email: zeiger{at}niehs.nih.gov