Showing papers on "Ames test published in 1995"
TL;DR: It seems that IRM, Super-EBA, and MTA are not mutagenic as measured by the Ames Test.
119 citations
TL;DR: Results indicate that nicotine and its major metabolites are not genotoxic in the assays conducted.
Abstract: Nicotine is a naturally occurring alkaloid found primarily in members of the solanaceous plant family, which includes tobacco. Nicotine is rapidly absorbed by humans and then metabolized, primarily by cytochrome P450's. Studies on the genotoxic potential of these metabolites are limited. Nicotine and four of its major metabolites: cotinine, nicotine-N'-oxide, cotinine-N-oxide, and trans-3'-hydroxycotinine were evaluated for genotoxic potential in the Salmonella mutagenicity assay (strains TA98, TA100, TA1535, TA1537, and TA1538) at concentrations ranging from 0 to 1000 micrograms/plate and in the Chinese hamster ovary sister-chromatid exchange (SCE) assay at concentrations ranging from 0 to 1000 micrograms/ml. All assays were conducted with and without S9 metabolic activation. None of the five compounds increased the frequency of mutations or the frequency of SCEs. These results indicate that nicotine and its major metabolites are not genotoxic in the assays conducted.
103 citations
TL;DR: Results suggest that MX and “MX‐like” compounds account for much of the mutagenic activity and specificity of the nonvolatile organics in drinking water and that these halogenated organics are especially capable of promoting misincorporation by the DNA replication complex.
Abstract: Drinking water samples were prepared in a pilot-scale treatment plant by chlorination (Cl2), chloramination (NH2Cl), ozonation (O3), or O3 followed by Cl2 or NH2Cl; and the nonvolatile acidic organics of the raw and treated waters were extracted by XAD/ethyl acetate and evaluated for mutagenicity in Salmonella (-S9). The extracts were 2-8 times more mutagenic in TA100 than in TA98, and the mutagenic potencies of the water extracts ranked similarly in both strains: Cl2 > O3 + Cl2 > NH2Cl > O3 + NH2Cl > O3 > raw. 3-Chloro-4-(dichloromethyl)-5-hydroxy-2(5H)-furanone (MX), which was estimated to account for approximately 20% of the mutagenic activity of the extracts, was shown to be the most potent compound tested thus far in a prophage-induction assay in Escherichia coli and a forward-mutation assay in Salmonella TM677. The mutations in approximately 2,000 revertants of TA98 and TA100 induced by MX and the water extracts were analyzed by colony probe hybridization and polymerase chain reaction/DNA sequence analysis. The water extracts and MX produced similar mutation spectra, which consisted in TA100 of predominantly of GC-->TA transversions in the second position of the CCC (or GGG) target of the hisG46 allele. This spectrum resembles that produced by large aromatic compounds and is distinct from that produced by alkylating agents and the semivolatile drinking water mutagen dichloroacetic acid. In TA98, MX and those water extracts resulting from the introduction of the chlorine atom produced 50-70% hotspot 2-base deletions and 30-50% complex frameshifts (frameshifts with an adjacent base substitution--mostly GC-->TA transversions as found in TA100). No other compound or mixture is known to induce such high frequencies of complex frameshifts. These results suggest that MX and "MX-like" compounds (possibly halogenated aromatics, such as halogenated polycyclic aromatic hydrocarbons) account for much of the mutagenic activity and specificity of the nonvolatile organics in drinking water and that these halogenated organics are especially capable of promoting misincorporation by the DNA replication complex. This study provides further evidence that the mutation spectrum of a complex mixture reflects the dominance of one or a few classes of chemical mutagens within the mixture.
85 citations
TL;DR: The effect of carcinogen exposure on intrachromosomal recombination in a human cell line was determined and it was found that these deletion events were induced by exposure to the Salmonella assay positive carcinogens UV, gamma-rays and methyl methanesulfonate, as well as the Salbornella assay negative carcinogens Aroclor 1221, benzene and thiourea.
Abstract: A major portion of new cases of cancer may be linked to environmental carcinogens. The Ames (Salmonella) test is currently the most widely used short-term test to predict carcinogenic properties of compounds. However, approximately 50% of all carcinogens have been sufficiently tested in long-term animal bioassays do not induce mutations in the Salmonella assay, and many of these carcinogens are also not detectable by other short-term assays. In the work described here we determined the effect of carcinogen exposure on intrachromosomal recombination in a human cell line. The recombination events caused the deletion of one copy of a duplication of exons 2 and 3 of the hprt gene. We found that these deletion events were induced by exposure to the Salmonella assay positive carcinogens UV, gamma-rays and methyl methanesulfonate, as well as the Salmonella assay negative carcinogens Aroclor 1221, benzene and thiourea. These data may further support the accumulating evidence that recombination and deletions may be important in carcinogenesis.
67 citations
TL;DR: The genetic toxicity of chlorpyrifos was examined by employing several end points such as gene mutations in bacteria and mammalian cell cultures, cytogenetic abnormalities in mammalian cells both in vitro and in vivo and induction of DNA damage and repair in rat hepatocytes in vitro.
Abstract: The genetic toxicity of chlorpyrifos [O,O,-diethyl-O-(3,5,6-trichloro-2- pyridinyl)phosphorothioate, C.A.S. Number: 2921-88-2)], an organophosphate insecticide, was examined by employing several end points such as gene mutations in bacteria (Ames test) and mammalian cell cultures (CHO/HGPRT assay), cytogenetic abnormalities in mammalian cells both in vitro (rat lymphocyte chromosomal aberration test, RLCAT) and in vivo (mouse bone marrow micronucleus test) and induction of DNA damage and repair in rat hepatocytes in vitro. There was no indication of genotoxic activity for chlorpyrifos in any of these assays. These results are consistent with the reported lack of carcinogenic potential for chlorpyrifos in both mice and rats.
60 citations
TL;DR: These PAH atmospheric reaction products are estimated to account for a significant portion of the mutagenic activity seen in gas- and particle-phase ambient sample extracts using this bioassay.
Abstract: A series of 2-4-ring polycyclic aromatic hydrocarbons (PAH) were reacted under simulated atmospheric conditions in an environmental chamber. The reactant mixtures were adsorbent collected, extracted, fractionated by HPLC, and tested for mutagenic activity in a microsuspension modification of the Ames Salmonella bioassay (strain TA98, -S9). GC/MS analyses were performed on the mutagenic HPLC fractions for identification of the PAH reaction products. In general, the PAH that were studied can be divided into two categories: those which formed mutagenic nitro-PAH products and those which produced more polar mutagenic products, including nitro-PAH lactones. These PAH atmospheric reaction products are estimated to account for a significant portion of the mutagenic activity seen in gas- and particle-phase ambient sample extracts using this bioassay
59 citations
Journal Article•
TL;DR: It is shown that the requirement for S9 can be obviated by the engineered expression of enzymes of bioactivation within the bacterial cell, and an Ames tester strain is constructed, expressing both aromatic amine N-acetyltransferase and human cytochrome P4501A2, which detects aromaticAmine mutagenicity in the absence of S9.
Abstract: The most widely used bioassay in genetic toxicology is the Ames test, which combines a bacterial mutagenicity assay (reversion of Salmonella typhimurium histidine-auxotrophic tester strains) with an exogenous bioactivation system (hepatic postmitochondrial supernatant or "S9"). The enzymatic activities of S9 prepared from the tissues of experimental animals are difficult to control. We show that the requirement for S9 can be obviated by the engineered expression of enzymes of bioactivation within the bacterial cell. With this strategy, reactive metabolites are produced inside the bacterial cell, proximate to the genetic target. Species boundaries can be crossed, and chimeric or mutant enzymes can be studied. We have constructed an Ames tester strain, expressing both aromatic amine N-acetyltransferase and human cytochrome P4501A2, which detects aromatic amine mutagenicity in the absence of S9.
56 citations
TL;DR: Two structure-activity relationships were noted: (1) the genotoxic activity of haloacetonitriles containing bromine substituents appeared higher than the corresponding chlorinated acetonitRiles and (2) the clastogenic activity of the chlorination acetonItriles increased with the number of chlorine substituENTS.
Abstract: Three short-term assays (the SOS chromotest, the Ames-fluctuation test and the newt micronucleus test) were carried out to evaluate the genotoxicity of six halogenated acetonitriles identified in chlorinated waters (monochloro-, dichloro-, trichloro-, monobromo-, dibromo- and bromochloroacetonitrile). With the SOS chromotest, three of the chemicals studied (dichloro-, dibromo- and bromochloroacetonitrile) were found to induce primary DNA damage in Escherichia coli PQ37. In the Ames-fluctuation test, all the compounds except dibromoacetonitrile showed mutagenic activity on Salmonella typhimurium strain TA100. The newt micronucleus assay detected a clastogenic effect on the peripheral blood erythrocytes of Pleurodeles waltl larvae for all the six haloacetonitriles studied. Moreover, two structure-activity relationships were noted: (1) the genotoxic activity of haloacetonitriles containing bromine substituents appeared higher than the corresponding chlorinated acetonitriles and (2) the clastogenic activity of the chlorinated acetonitriles increased with the number of chlorine substituents.
56 citations
TL;DR: The sensitivity to metals of all the assays used was maintained when they were dissolved in sewage, although there was a slight increase in the sensitivity thresholds.
Abstract: Heavy metal genotoxicity was evaluated by using different microbial tests. Four genotoxicity assays were employed: the Ames test, the E. coli WP2 test, the Mutatox™ test detecting mutagenicity, and the SOS assay with E. coli-detecting enzyme induction. All the metals tested (cadmium, chromium, copper, mercury, nickel, and zinc) were detected as genotoxic by the Mutatox™ and the SOS tests. The Ames test and the E. coli WP2 assay only detected chromium as genotoxic, causing a mutagenic effect. The sensitivity to metals of all the assays used was maintained when they were dissolved in sewage, although there was a slight increase in the sensitivity thresholds.
46 citations
TL;DR: It is suggested that PC extracts and emodin act as blocking and/or suppressing agents to reduce the direct-acting mutagenicity of 1-NP.
Abstract: Polygonum cuspidatum S. (PC) is frequently used as a laxative and an anticancer drug in Chinese medicine. The inhibitory effect of this herb and its component, emodin, on the direct-acting mutagenicity of 1-nitropyrene (1-NP) was examined using the Ames/microsomal test with Salmonella typhimurium TA98 and the genotoxicity of 1-NP was evaluated using the SOS chromotest with E. coli PQ37. Emodin and water extracts of PC markedly decreased the mutagenicity of 1-NP in a dose-dependent manner in both assay systems. Furthermore, emodin and the extracts of PC significantly inhibited the formation of 1-NP DNA adducts in S. typhimurium TA98 in the 32P-postlabeling study. The results suggest that PC extracts and emodin act as blocking and/or suppressing agents to reduce the direct-acting mutagenicity of 1-NP.
46 citations
TL;DR: QSAR (Quantitative Structure Activity Relationships) was used to develop a model to describe the genotoxic mechanism of hydrazine compounds, taking advantage of the results of previous mutagenicity studies, which indicate that unsymmetrically alkylated hydrazines can cause DNA-lesions which are lethal in repair-deficient strains.
Abstract: Hydrazine compounds are important industrial and laboratory chemicals. Many of them are carcinogenic in animal tests. Although the carcinogenicity is well established, the results of mutagenicity tests performed on alkylhydrazines vary greatly in different studies. In an attempt to clarify the situation we have applied Salmonella typhimurium TA102 tests to hydrazine and its mono- and dimethyl derivatives. These compounds were also tested by an Escherichia coli DNA repair-assay. The results of the repair tests indicate that unsymmetrically alkylated hydrazines can cause DNA-lesions which are lethal in repair-deficient strains. Finally QSAR (Quantitative Structure Activity Relationships) was used to develop a model to describe the genotoxic mechanism of hydrazine compounds, taking advantage of the results of previous mutagenicity studies. Energy of the lowest unoccupied molecular orbital together with octanol-water partition coefficient explains nearly completely the mutagenic activity of alkylated hydrazine compounds included in the analysis. The mutagenic activity of unsubstituted hydrazine is apparently based on different mechanisms.
TL;DR: A methanol extract from Vitex rotundiforia showed a suppressive effect on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen (3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1)), which requires liver metabolizing enzymes as mentioned in this paper.
Abstract: A methanol extract from Vitex rotundiforia showed a suppressive effect on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen (3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1)), which requires liver metabolizing enzymes. The methanol extract from V. rotundiforia was re-extracted with dichloromethane, n-butanol, and water, respectively. A suppressive compound in the dichloromethane extract fraction was isolated by SiO 2 column chromatography and identified as (+)-polyalthic acid by EI-MS and 1 H and 13 C NMR spectroscopy. (+)-Polyalthic acid suppressed the SOS-inducing activity of Trp-P-1 in the umu test. Gene expression was suppressed 90% at <0.32 μmol/mL, and the ID 50 value was 0.19 μmol/mL. (+)-Methyl polyalthate also suppressed the SOS-inducing activity of Trp-P-1 in the umu test. Gene expression was suppressed 57% at <0.32 μmol/mL, and the ID 50 value was 0.29 μmol/mL. (+)-Polyalthic acid and (+)-methyl polyalthate were also assayed with the mutagens 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide) and activated Trp-P-1, but these compounds did not show a suppressive effect on the SOS induction of these mutagens. The antimutagenic activities of (+)-polyalthic acid and (+)-methyl polyalthate against Trp-P-1, furylfuramide, and activated Trp-P-1 were tested by an Ames test using S. typhimurium TA100. The results indicated that (+)-polyalthic acid suppressed the mutagenicity of Trp-P-1 and the mutagenicity of activated Trp-P-1 and (+)-methyl polyalthate suppressed the mutagenicity of Trp-P-1.
TL;DR: Addition of the reduced form of glutathione to the assay system resulted in decreased mutagenicity of 2-hydroxy-2',6'-diethylacetanilide, suggesting that these products may act as toxic electrophiles that bind directly to DNA/RNA.
Abstract: The Salmonella/microsome assay and the micronucleus test were employed to evaluate the chronic toxicity potential of environmental degradative products of alachlor. Degradative products include 2-hydroxy-2',6'-diethyl-N-(methoxymethyl)acetanilide ; 2-chloro-2',6'-diethylacetanilide ; 2,6-diethylacetanilide; 2,6-diethylaniline ; 2,6-diethyl-N-(methoxymethyl)aniline ; 2-hydroxy-2',6'-diethylacetanilide; and 2,6-diethyl-N-(methoxymethyl)acetanilide. 2-Hydroxy-2',6'-diethylacetanilide and 2-chloro-2',6'-diethylacetanilide were weakly mutagenic to Salmonella strain TA100, with reversion rates of 54.6 and 58.4 His + revertants/μmol, respectively. Reversion was dependent on bioactivation with phenobarbitol-induced microsomes. Addition of the reduced form of glutathione to the assay system resulted in decreased mutagenicity of 2-hydroxy-2',6'-diethylacetanilide, suggesting that these products may act as toxic electrophiles that bind directly to DNA/RNA. None of the environmental degradative products tested acted as clastogens in the micronucleus test, even at near-lethal doses (ca. 500 μg/g). Only 2-hydroxy-2',6'-diethyl-N-(methoxymethyl)acetanilide cross-reacts (ca. 40%) with commercially available alachlor immunoassay test kits. The two mutagenic compounds did not cross-react.
TL;DR: Reconstituted non-fat dry milk powder, fermented by a mixture of Streptococcus thermophilus CH3 and Lactobacillus bulgaricus 191R to produce yogurt, was freeze-dried and extracted in acetone to determine if formation of antimutagenic activity required bacterial growth.
Abstract: Reconstituted non-fat dry milk powder, fermented by a mixture of Streptococcus thermophilus CH3 and Lactobacillus bulgaricus 191R to produce yogurt, was freeze-dried and extracted in acetone. After evaporation of the acetone, the extract was dissolved in dimethyl sulfoxide (DMSO) and tested for antimutagenicity. In the Ames test, significant dose-dependent activity was observed against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 4-nitro-quinoline-N-oxide (4NQO), 3,2'-dimethyl-4-aminobiphenyl (DMAB), 9,10-dimethyl-1,2-benz[a]anthracene (DMBA), and 3-amino-1-methyl-5H-pyrido[4,3-b]indole acetate (Trp-P-2). Weak activity was observed against 1,2,7,8-diepoxyoctane (DEO), and no activity was observed against methyl methanesulfonate (MMS), ethyl methanesulfonate (EMS), or aflatoxin B1 (AFB1). In a related assay (Saccharomyces cerevisiae D7), significant antimutagenic activity was detected against MNNG and 4NQO. Activity against the experimental colon carcinogens MNNG and DMAB was examined further, as assayed in the Ames test (Salmonella typhimurium TA100). Compounds responsible for both activities were less soluble in aqueous solutions than in DMSO. Adjustment of yogurt pH to 3, 7.6, or 13 prior to freeze-drying and acetone extraction did not significantly alter the amount of anti-MNNG activity recovered. In contrast, extractability of anti-DMAB activity was significantly greater at acidic pH. Conjugated linoleic acid, a known dairy anticarcinogen, failed to inhibit mutagenesis caused by either mutagen, suggesting that other yogurt-derived compound(s) are responsible. Unfermented milk was treated with lactic acid, yogurt bacteria without subsequent growth, or both, to determine if formation of antimutagenic activity required bacterial growth. Extracts of the milk treatments exhibited the same weak antimutagenicity observed in unfermented milk, approximately 2.5-fold less than in the yogurt extracts, suggesting that antimutagenic activity is associated with bacterial growth.
TL;DR: Assessing occupational exposure to cytostatic drugs with strain TA 102 requires additional studies to determine environmental mutagens which can be detected by this strain.
Abstract: A study was undertaken to evaluate the urine mutagenicity of 63 individuals working in four hospital departments. The exposed group included 38 subjects who were exposed to various cytostatic drugs and/or contaminated material from treated patients. The control group included 25 individuals of the hospital personnel. Urine mutagenicity was monitored by the Ames test using tester strains TA 98 + S9 Mix and TA 102 — S9 Mix. Urine samples were collected before and after the working periods. A total of 29/116 (25%) urine samples were mutagenic for either strain. Among the mutagenic samples, 24/29 were mutagenic for tester strain TA 98 exclusively. No significant correlation could be found between occupational exposure to cytostatic drugs and urine mutagenicity evaluated by the strain TA 98 + S9 Mix. Smoking was the main environmental factor that modulated urine mutagenicity with TA 98. Three subjects in the exposed group had mutagenic urine samples at the end of the working period with strain TA 102 — S9 Mix. This mutagenicity was related to occupational exposure to cisplatin. In the control group, one individual had mutagenic samples before and after the working period. Assessing occupational exposure to cytostatic drugs with strain TA 102 requires additional studies to determine environmental mutagens which can be detected by this strain.
TL;DR: The toxicity of water samples and extracts was tested with Microtox assay, and acid fractions of the extracts were more toxic than the neutral fractions, which indicates that components responsible for toxic and mutagenic response were at least partly separated between acid and neutral fraction respectively.
Abstract: The present study was conducted on the waters of the Sora river and effluents entering the river. The samples were extracted with XAD-2 resin at different pH and tested for mutagenicity with the modified Ames test using strains S. typhimurium TA98 and TA100. The majority of the mutagenic activity of the samples was found in the neutral pH fraction of the extracts. Strain TA98 in the presence of metabolic activation was the most sensitive condition of mutagenicity. Of the eleven sample extracts, six were positive; neutral fractions of the effluent from wastewater treatment plant, the water leaching from the municipal dump, the water from the lake lying beneath the dump and the untreated effluent, and acid fractions of two samples taken directly from the river. The water leaching from the municipal dump was also mutagenic and toxic without previous extraction. Mutagenic responses before and after extraction of this sample indicate that components responsible for mutagenicity were partly extracted in the neutral fraction. The toxicity of water samples and extracts was tested with Microtox assay, and acid fractions of the extracts were more toxic than the neutral fractions. Comparing the toxicity to the mutagenicity data indicates that components responsible for toxic and mutagenic response were at least partly separated between acid and neutral fraction respectively.
TL;DR: In this article, heavy metal concentrations in wastewaters from the industrial estate of Aligarh city (U.P.) India were determined and the analysis of test samples revealed significantly higher levels of Fe, Zn, Cu, Cr, and Ni compared with the pure domestic samples.
Abstract: Heavy metal concentrations in wastewaters from the industrial estate of Aligarh city (U.P.) India were determined. The analysis of test samples revealed significantly higher levels of Fe, Zn, Cu, Cr, and Ni compared with the pure domestic samples. Raw wastewaters were screened for mutagenic potential using the Ames Salmonella/microsomal test. Mutagenic activity was observed with industrial as well as domestic waste samples. Salmonella typhimurium strains TA102 and TA104 were the most sensitive both in the absence and presence of S9 fraction. A significant decrease in the survival of DNA repair defective Escherichia coli mutants recA, lex A, and polA was observed as compared to their wild-type counterparts in the presence of wastewater. © by John Wiley & Sons, Inc.
TL;DR: It is suggested that serum-free culture allows the stable and highly sensitive measurement of induced MFO activity, and that studies of MFO induction by environmental samples using human hepatoma Hep G2 cells should provide helpful information regarding the risk associated with environmental contaminants.
TL;DR: The mutagenic potency of urinary extracts of coke oven workers depended on exposure to PAHs, tobacco smoking habits, and consumption of fried, grilled or barbecued meat, and epidemiological evidence of the increased risk of renal and urinary tract tumours in these workers was strengthened.
Abstract: The influence of occupational exposure to polycyclic aromatic hydrocarbons (PAHs) on urinary mutagenic activity was assessed in 75 coke oven workers, using a highly sensitive bacterial mutagen technique (extraction with C18 resin and liquid micro-preincubation test on strain TA98 of Salmonella typhimurium in the presence of metabolizing and deconjugating enzymes). Exposure to PAHs was assessed according to the urinary excretion of 1-pyrenol; the main confounding factors were checked by the number of cigarettes smoked per day and the levels of nicotine and its metabolites in urine, or by ascertaining whether recommended dietary restrictions had been followed. Of the 20 urine samples which turned out to be positive (producing at least double the number of spontaneous revertants), 19 (95%) belonged to smokers. Only one non-smoker had obvious urinary mutagenic activity, and was highly exposed occupationally to PAHs (urinary 1-pyrenol of 3.930 mumol/mol of creatinine). Of the five urine samples from subjects who had not followed the recommended diet, two (40%) were clearly mutagenic. Multiple regression analysis (n = 67) showed that the presence of samples positive for urinary mutagenic activity depended only on smoking habits, if this confounding factor was assessed according to the number of cigarettes smoked per day, while the significant influence of exposure to PAH could be shown when the confounding factor was objectively estimated according to the urinary levels of nicotine and its metabolites. Assessment of the mutagenic potency of urinary extracts (net revertants/mmol creatinine) confirmed the strong influence of smoking habits on urinary mutagenic activity (all smokers 2156 +/- 2691 versus non-smokers 939 +/- 947 net revertants/mmol creatinine; Mann-Whitney test: P < 0.01). In smokers highly exposed to PAHs, greater excretion of mutagens with respect to low-exposure smokers was revealed (3548 +/- 4009 versus 1552 +/- 1227 net revertants/mmol creatinine; Mann-Whitney test: P < 0.01). Multiple regression analysis showed that the mutagenic potency of urinary extracts of coke oven workers depended on exposure to PAHs, tobacco smoking habits, and consumption of fried, grilled or barbecued meat. Increased urinary mutagenic activity strengthens epidemiological evidence of the increased risk of renal and urinary tract tumours in these workers. The presence of mutagenic metabolites in urine as a result of occupational exposure to PAH may be demonstrated only by using highly sensitive techniques for assessing urinary mutagenic activity in studies which include careful checking of the main confounding factors.
Journal Article•
TL;DR: The synthesized N-acetoxy-SMX was found to be weakly mutagenic to the Salmonella typhimurium TA100 strain in the Ames test, and the N- acetoxy metabolites of sulfonamides could potentially play a role in mediating sulfonamide idiosyncratic adverse drug reactions.
Abstract: Variation in the formation and disposition of the hydroxylamine of (SMX-HA) is thought to play an important role in the pathogenesis of sulfamethoxazole (SMX)-induced idiosyncratic adverse drug reactions. We hypothesized that, in analogy to carcinogenic arylamines, SMX-HA might be further converted to an electrophilic N-acetoxy metabolite which could play a role in mediating SMX toxicity. Accordingly, we chemically synthesized N-acetoxy-SMX, and examined the characteristics of its formation, metabolism, cytotoxicity and mutagenicity in human and bacterial test systems. The human arylamine N-acetyl-transferases, (NAT)1 and NAT2, were capable of converting SMX-HA to N-acetoxy-SMX. NAT1 and NAT2 possessed similar affinities for SMX-HA (apparent Km values of 650 and 520 microM, respectively), but the apparent maximal velocity of the NAT1-mediated acetylation was higher than that of NAT2. (1332 vs. 37 nmol/min/U of immunoreactive NAT protein). Human peripheral blood mononuclear cells 12,000 x g supernatant fractions converted N-acetoxy-SMX mainly back to SMX-HA, and also to a lesser extent to SMX, at clinically relevant concentrations. Similar pathways were observed in human hepatic cytosolic fractions. In a cytotoxicity assay, N-acetoxy-SMX was significantly more toxic to human peripheral blood mononuclear cells than SMX-HA (16.6 vs. 11.5% dead cells at a concentration of 300 microM). N-acetoxy-SMX was weakly mutagenic to the Salmonella typhimurium TA100 strain in the Ames test. These data suggest that the N-acetoxy metabolites of sulfonamides could potentially play a role in mediating sulfonamide idiosyncratic adverse drug reactions.
TL;DR: Evidence is provided that quercetin and other flavonoids found to be mutagenic in the Ames test can bind DNA by intercalation and that their affinity for DNA increased following the same sequence of their biological activity.
Abstract: Quercetin and other flavonoids which had been previously found to be mutagenic in the Ames test, have been proved to inhibit tumor development in several experimental animal models. We studied the interaction between DNA and a series of flavonoids whose biological activity was known to span a wide range of potency: quercetin (the most active), morin, rutin, naringin, and 2,3-dihydroquercetin (inactive). The sensitivity of equilibrium binding analysis carried out by the dextran-polyethylene glycol-H 2 O biphase system was not high enough to reveal and evaluate the binding affinity of these flavonoids toward DNA. The much more sensitive flow linear dichroism technique provided evidence that they can bind DNA by intercalation and that their affinity for DNA increased following the same sequence of their biological activity
TL;DR: Results indicate that saikosaponin a and ginsenoside Rbl may enhance DNA repair, and gINSenosideRbl may also have the ability to inactivate the mutagenic activity of AF‐2 directly.
Abstract: The antimutagenic effects of nine active compounds in the Chinese herbal medicine "sho-saiko-to" on mutagenesis induced by a direct-acting mutagen, 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2) were investigated in Salmonella typhimurium, strain TA100. The active compounds examined were classified into two major groups, saponins and flavonoids, the former comprising glycyrrhizin, saikosaponins a, c, and d, and ginsenosides Rb1 and Rg1, and the latter, baicalin, baicalein and wogonin. Saikosaponin a and ginsenoside Rb1 were found to reduce the mutagenicity of AF-2 significantly when applied post-AF-2-treatment in the Salmonella mutagenicity assay. Ginsenoside Rb1 also decreased the mutagenic activity of AF-2 in a simultaneous treatment protocol. The results indicate that saikosaponin a and ginsenoside Rb1 may enhance DNA repair, and ginsenoside Rb1 may also have the ability to inactivate the mutagenic activity of AF-2 directly. On the other hand, saikosaponin d and baicalin showed a slight enhancing effect. None of the compounds, except baicalein, showed any toxic effect on the test strain. These findings may be useful for the development of chemopreventive agents.
TL;DR: In this article, a dichloromethane extract from Dictamnus dasycarpus showed a suppressive effect on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen 2-(2-furyl)-3-(5-nitro-2-Furyl)acrylamide (furylfuramide).
Abstract: A dichloromethane extract from Dictamnus dasycarpus showed a suppressive effect on umu gene expression of the SOS response in Salmonella typhimurium TA1535/pSK1002 against the mutagen 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (furylfuramide). The suppressive compound in the dichloromethane extract from D. dasycarpus was isolated by SiO 2 column chromatography and identified as isofraxinellone by EI-MS and 1 H and 13 C NMR spectroscopy. Isofraxinellone exhibited an inhibition of the SOS-inducing activity of furylfuramide in the umu test. Gene expression was suppressed completely at less than 0.86 μmol/mL, and the ID 50 value was 0.35 μmol/mL. Fraxinellone, which was one of the major components in D. dasycarpus, was also isolated, but this compound did not show any suppressive effect on the SOS induction of furylfuramide. Isofraxinellone was also assayed with the mutagen 3-amino-1,4.dimethyl-5H-pyrido[4,3-b]indole (Trp-P-1), which requires liver metabolizing enzymes, and showed a suppressive effect similar to that with furylfuramide. Its ID 50 value against Trp-P-1 was 0.50 μmol/mL. The antimutagenic activities of isofraxinellone against furylfuramide and Trp-P-1 were tested by an Ames test using Salmonella typhimurium TA100, which indicated that isofraxinellone showed antimutagenic activity.
TL;DR: Results indicate that HTHQ is a powerful antimutagenic compound and specifically acts against heterocyclic amines.
Abstract: Antimutagenic effects of a novel lipophilic antioxidant, 1-O-hexyl-2,3,5-trimethylhydroquinone (HTHQ), and other known antioxidants against heterocyclic amine- or other mutagen-induced mutagenesis were examined in the Ames assay using Salmonella strain TA 98 to access the chemo-preventive effects of antioxidants on heterocyclic amine-induced carcinogenesis. Further the mechanisms of inhibition by HTHQ were accessed. HTHQ was shown to potently inhibit mutagenesis induced by all of 8 different heterocyclic amines at rates between 100% and 63% in the presence of S9 mix. When the protection of HTHQ against 2-amino-6- methyldipyrido[1,2-alpha:3',2'-d]imidazole (Glu-P-1)-induced mutagenesis was compared with known antioxidants t-butylhydroquinone, propyl gallate, BHA, BHT and alpha-tocopherol, HTHQ showed the greatest effect. Among hexyl, butyl, ethyl and methyl derivatives of 1-O-alkyl-2,3,5-trimethylhydroquinone, HTHQ was the most effective in inhibiting Glu-P-1-, 3-amino-1-methyl-5-H-pyrido[4,3-b]indole (Trp-P-2)- or 2-amino-3-methylimidazo[4,5-f]quinoline (IQ)-induced mutagenesis. On the other hand, HTHQ did not inhibit mutagenic activity induced by other mutagens such as N-methyl-N'-nitro-N-nitrosoguanidine (MNNG), 2-(2-furyl)-3-(5-nitro-2-furyl)acrylamide (AF-2) and benzo[a]pyrene. HTHQ weakly inhibited that due to direct mutagen 2-nitro derivative of 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline (MeIQx) only in the presence of S9 mix. No such influence on a 2-nitro derivative of 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ) or 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP)-induced mutagenesis, was observed with or without the S9 mix. HTHQ slightly inhibited mutagenesis induced by activated Glu-P-1, a direct acting proximate metabolite of Glu-P-1, in the absence of the S9 mix. HPLC analysis revealed activated Glu-P-1 to be formed by incubating Glu-P-1 with the S9 mix, but this was considerably decreased by the addition of HTHQ. These results indicate that HTHQ is a powerful antimutagenic compound and specifically acts against heterocyclic amines. Its antimutagenic activity appeared to exert by both inhibiting metabolic activation of heterocyclic amines and action on activated N-hydroxy species.
TL;DR: The toxicological evaluation of urinary human epidermal growth factor (u-hEGF) included mutagenicity, single and repeated dose general toxicity, and teratogenicity studies in various animal species and no mutagenic or clastogenic effects were found.
Abstract: The toxicological evaluation of urinary human epidermal growth factor (u-hEGF) included mutagenicity, single and repeated dose general toxicity, and teratogenicity studies in various animal species. The mutagenic potential of u-hEGF was tested in vitro (Ames test, chromosome aberration in human lymphocytes, unscheduled DNA synthesis in HeLa cells) and in vivo (chromosome aberration in Chinese hamster bone marrow and micronucleus test in rat bone marrow). No mutagenic or clastogenic effects were found. The acute toxicity of u-hEGF was evaluated in mice and rats, using single subcutaneous (sc) or intravenous (iv) injection of 15 mg/kg. No toxic effects were observed. Four-week iv daily administration of u-hEGF at the doses of 0.3, 0.9, and 3 mg/kg in the SD rat followed by 2 wk of compound withdrawal induced pronounced and generally dose-related effects (i.e., epithelial hyperplasia) in a wide range of tissues and organs, at all doses. However, these effects were not apparently detrimental to the general he...
TL;DR: The good efficiency of this in vitro test on E.coli for the detection of trihalomethanes with bromine substituents was exhibited, unlike previous investigations in which the SOS chromotest was always the least interesting assay.
Abstract: Three short-term assays (the SOS chromotest, the Ames-fluctuation test and the newt micronucleus test) were carried out to evaluate the genotoxicity of four trihalomethanes (chloroform, bromodichloromethane, chlorodibromomethane and bromoform). With the SOS chromotest, all the chemicals studied except chloroform were found to induce primary DNA damage in Escherichia coli PQ37. In the Ames-fluctuation test, only bromoform showed mutagenic activity on Salmonella typhimurium strain TA100. The newt micronucleus assay detected a clastogenic effect on the peripheral blood erythrocytes of Pleurodeles waltl larvae for bromodichloromethane and bromoform. It appeared that the presence of bromine substituent(s) generally led to significant genotoxic activity. Moreover, the use of the metabolic system significantly increased the genotoxicity of the brominated trihalomethanes in the SOS chromotest. Unlike previous investigations in which the SOS chromotest was always the least interesting assay, this study exhibited the good efficiency of this in vitro test on E.coli for the detection of trihalomethanes with bromine substituents.
TL;DR: In this paper, male Syrian golden hamsters were exposed for 1 or 2 weeks to smoke produced by commercial non-filter cigarettes for 5 consecutive days in a Hamburg type II smoking machine.
TL;DR: The low mutagenicity of moflomycin shown in this study enhances the potential advantage of this new derivative which displays a high antileukemic activity.
Abstract: The mutagenicity of a new anthracycline (moflomycin) with potent antileukemic activity was studied by the Ames test in four strains of Salmonella typhimurium (TA97a, TA98, TA100 and TA102), and compared to the mutagenicity of doxorubicin, widely used as antineoplastic agent. Unlike doxorubicin, moflomycin displayed no mutagenic activity in strains TA98 and TA100. Low mutagenicity was only observed in TA102 strain and was not enhanced after metabolic activation. This result indicates that moflomycin induce mutagenicity by reverting base-pair substitution. The structural changes in the sugar moiety may be involved in the reduced mutagenicity of moflomycin. The low mutagenicity of moflomycin shown in this study enhances the potential advantage of this new derivative which displays a high antileukemic activity.
TL;DR: A streamlined bacterial mutagenicity assay, the MINISCREEN, was developed to enable the rapid screening of a large number of chemical compounds on a purely qualitative basis and has proven its value as a screening method.
Abstract: A streamlined bacterial mutagenicity assay, the MINISCREEN, was developed to enable the rapid screening of a large number of chemical compounds on a purely qualitative basis. Experiments with a series of known carcinogens/mutagens and non-carcinogens/mutagens showed a good correlation with conventional bacterial mutagenicity assays (Ames tests), and the subsequent testing of over 300 candidate agricultural chemicals and over 100 industrial chemicals has proven its value as a screening method.
TL;DR: A series of aniline mustards and half-mustards targeted to DNA by linkage (through a polymethylene chain) to the bisbenzimidazole chromophore of pibenzimol have been evaluated for their mutagenic properties and mutagenicity data provided no supportive evidence for DNA alkylation.
Abstract: A series of aniline mustards and half-mustards targeted to DNA by linkage (through a polymethylene chain) to the bisbenzimidazole chromophore of pibenzimol (Hoechst 33258) have been evaluated for their mutagenic properties, as estimated in three strains of Salmonella typhimurium, and for their mitotic crossing-over and petite mutagenesis activities in Saccharomyces cerevisiae strain D5. Agarose gel electrophoresis studies showed that only the derivative with the longest linker chain cross-linked DNA, with the remaining compounds being monoalkylators. The parent (non-alkylator) minor groove binding ligand (Hoechst 33258) was inactive in the bacterial strains TA98 or TA100 but weakly mutagenic in TA102, and caused neither mitotic crossing-over nor 'petite' mutagenesis in yeast. Aniline half-mustard itself (monoalkylator) was an effective base-pair substitution mutagen (events in S. typhimurium strain TA100) with some frameshift mutagenesis activity in TA98, but showed only weak effects in the yeast assays, whereas aniline mustard (cross-linker) was inactive in these bacterial systems but caused substantial amounts of mitotic crossing-over in yeast. The composite molecules studied here showed effects more characteristic of the minor groove binding chromophore than of alkylating moieties. All showed weak mutagenic activity in TA102 and none in TA98. The only compound to show significant mitotic crossing-over ability was the long-chain derivative which cross-linked DNA. For most of the compounds, the mutagenicity data provided no supportive evidence for DNA alkylation. Since other evidence suggests this does occur readily, it is likely to have a different target to that seen with untargeted aniline mustards. The significant antitumor activity and low mutagenic potential shown by these compounds make them worthy of further study.