Direct-acting Mutagens Research Articles

Prenylated flavanones isolated from flowers of Azadirachta indica (the neem tree) as antimutagenic constituents against heterocyclic amines.

Four prenylated flavanones were isolated from the methanol extract of the flowers of Azadirachta indica (the neem tree) as potent antimutagens against Trp-P-1 (3-amino-1,4-dimethyl-5H-pyrido[4,3-b]indole) in the Salmonella typhimurium TA98 assay by activity-guided fractionation. Spectroscopic properties revealed that those compounds were 5,7,4'-trihydroxy-8-prenylflavanone (1), 5,4'-dihydroxy-7-methoxy-8-prenylflavanone (2), 5,7,4'-trihydroxy-3',8-diprenylflavanone (3), and 5,7,4'-trihydroxy-3',5'-diprenylflavanone (4). All isolated compounds were found for the first time in this plant. The antimutagenic IC(50) values of compounds 1-4 were 2.7 +/- 0.1, 3.7 +/- 0.1, 11.1 +/- 0.1, and 18.6 +/- 0.1 microM in the preincubation mixture, respectively. These compounds also similarly inhibited the mutagenicity of Trp-P-2 (3-amino-1-methyl-5H-pyrido[4,3-b]indole) and PhIP (2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine). All of the compounds 1-4 strongly inhibited ethoxyresorufin O-dealkylation activity of cytochrome P450 1A isoforms, which catalyze N-hydroxylation of heterocyclic amines. However, compounds 1-4 did not show significant inhibition against the direct-acting mutagen NaN(3). Thus, the antimutagenic effect of compounds 1-4 would be mainly based on the inhibition of the enzymatic activation of heterocyclic amines.

Mutagenicity of Water and Sediment Extracts from the Yongdinghe Watershed

Potential mutagenicities of water and sediment in Guanting Reservoir/ Yongdinghe River Watershed in Beijing, China were assessed using the Ame's tests for the organic pollutants. For different sampling sites, the results were indicative for the existence of mutagens. Furthermore, by using different types of Ames tests, different types of mutagens in water and in sediment were elucidated. The results on Ames tests for water concentrates and sediment extracts could be obviously differentiated. Mutagens in water were mainly direct-acting mutagens whereas in sediment they were mainly pro-mutagens, which exhibit mutagenic effects only after metabolic activation. In general, among all the six sampling sites, site-1, site-2 and site-4 were potentially at mutagenic risk. In a trial to find the causes of mutagenicities in the sediment samples, chemical analysis was performed for polychlorinated biphenyls (PCBs) and organochlorinated pesticides. However, the available data were not sufficient to explain the mutagenicity in the sediment. Integration of the results of Ames test and chemical analysis on overlying water and sediment samples in Guanting Reservoir and Yongdinghe River indicated that this catchment was moderately contaminated by PCBs and organochlorinated pesticides thereby causing a significant mutaginicity in water and sediment. Special attention should be given to the water quality in site-1 and sediment quality in site-4.

Direct detection of deletion mutations in the yeast DEL assay using quantitative PCR (TaqMan ®)

Established mutagenesis assays measure mutant frequencies at selectable loci. These assays work by encouraging the growth of mutants to form visible colonies while suppressing the growth of non-mutants. An alternative strategy is to detect DNA alterations directly. We present an example of this latter strategy using TaqMan ® to quantify deletion mutants in mixed cultures of Saccharomyces cerevisiae strain RS112. The RS112 strain contains two heteroallelic his3 sequences that share ∼400 bp homology and are separated by ∼7 kb of plasmid DNA. Spontaneous and chemical-induced strand breaks that occur in this region are repaired by intrachromosomal recombination, resulting in the loss of the plasmid DNA and creation of a His prototroph. Ordinarily, these prototrophs are detected by growth on His− medium over 2–3 days. In this case, we used TaqMan ® to selectively detect the DNA of deletion mutants in the presence of a large excess of DNA from non-mutants. This was accomplished using primers whose annealing sites were outside the region of DNA lost due to recombination. Thus, the primers were too far apart to produce PCR products using DNA from non-mutants, but produced a robust TaqMan ® signal using DNA from deletion mutants. Spontaneous and chemical-induced recombination frequencies (RF) were measured in a series of time-course and dose–response experiments with direct-acting mutagens. Interestingly, chemical-induced increases in RF were observed within a few hours of initiation of exposure, demonstrating that deletion mutations in RS112 can be fixed soon after DNA damage occurs. The ability to measure RF at any time during treatment will be useful for additional mechanistic studies. Chemical-induced increases in RF were also observed in the absence of selective growth conditions. As such, detection of deletion mutations with TaqMan may be applicable to measurements of RFs at non-selectable loci in yeast and other species. Finally, chemical-induced RFs after 17 h exposure were similar to those observed after 3 days growth on selective medium. The TaqMan ® assay may therefore be used to screen compounds more quickly for their ability to cause deletion mutations than is currently done by plating on selective medium.

Mutagenicity and DNA damage studies of N-acyloxy-N-alkoxyamides--the role of electrophilic nitrogen.

N-Acyloxy-N-alkoxyamides are anomeric amides that are direct-acting mutagens. They have been shown to damage DNA in the major and the minor grooves in a pH and sequence-selective manner. In acidic media, they damage adenines at N3 in the minor groove but above neutral pH, only guanine is damaged at N7 in the major groove. Both the acyloxy leaving group and the alkoxy group at the amide nitrogen are responsible for their electrophilicity and Salmonella mutagenicities in TA 100 and DNA damage data confirm that the mutagens react with DNA in an intact form, rather than by solvolysis to electrophilic nitrenium ions in the cytosol, or in vitro, prior to reacting with DNA. Hydrophobicity plays a role in both mutagenicity and DNA damage.

Development and characterization of a stable epithelial cell line from Muta Mouse lung.

We have isolated and characterized a stable epithelial cell line from Muta Mouse lung that is a suitable complement to the in vivo assay system. The cells are contact inhibited, forming a flat monolayer, and retain several epithelial/pulmonary characteristics. The genome is stable across more than 50 generations, with a modal chromosome number of 78. Spontaneous rates of micronuclei (19.2 +/- 1.4 per 1,000), sister chromatid exchanges (0.25 +/- 0.004 per chromosome), and chromosome aberrations ( approximately 4%) are lower than, or comparable to, other transgenic cell lines currently used in mutagenicity research. Fluorescence in situ hybridization analyses showed that 80% of cells contain three lambdagt10lacZ loci. Slot-blot analyses indicated that the average cell contains approximately 17 transgene monomers. Spontaneous mutant frequency at the lacZ transgene is stable (39.8 +/- 1.1 x 10(-5)), and the direct-acting mutagens N-ethyl-N-nitrosourea and ICR-191 yielded increases in mutant frequency of 6.3- and 3.2-fold above control, respectively. Benzo[a]pyrene (BaP) exposure increased mutant frequency more than 25-fold above control and did not require an exogenous metabolic activation mixture. Inhibition of Cyp1A1 by 5 microM alpha-naphthoflavone eliminated BaP mutagenesis. Activation and mutation induction by the heterocyclic amine 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine required a low concentration (0.05% v/v) of exogenous rat liver S9. High activity of alpha, micro, and pi glutathione-S-transferase isozymes appears to confer resistance to the cytotoxic effects of xenobiotics. The cell line is a suitable complement to the in vivo Muta Mouse assay, and provides an opportunity for routine in vitro mutagenicity testing using an endpoint that is identical to that employed in vivo.

Bioassay-Guided Isolation of Antimutagenic Factors from Fruits of Terminalia Bellerica

In the course of our search for novel polyphenolic antimutagenic agents from medicinal plants, we examined water, acetone, and chloroform extracts of Terminalia bellerica for their antimutagenic potency using the Ames Salmonella/microsome assay. Acetone extract exhibited variable inhibitory activity of 65.6%, and 69.7% with 4-O-nitrophenylenediamine (NPD) and sodium azide, respectively (as direct-acting mutagens), and 81.4% with 2-aminofluorene (2AF) (an S9-dependent mutagen), in the preincubation mode of experimentation. Inhibition with chloroform and water extracts was rather insignificant. Studies are well underway to isolate and identify the active polyphenolic compounds from acetone extract, which could be used as effective chemopreventive agents in the future.

Early Reappearance of Primary Solid Cancer in Patients Treated With Purine Analogs

Two patients, observed at our institution, developed, after treatment with flu-darabine, an early reappearance of metastatic primary solid cancers which were previously in long-lasting, complete remission. Patients had earlier suffered from a solid cancer considered cured and, subsequently, developed a lymphoid disorder treated with fludarabine. The two patients developed histologically confirmed hepatic metastasis from breast cancer and colic adenocarcinoma respectively 11 and 4 months after the beginning of fludarabine-therapy.Purine analogs have been reported to be effective against chronic lymphocytic leukemia and indolent lymphomas. However, these drugs induce severe immunodeficiency. In addition to the infectious diseases related to the treatment, the use of these drugs could facilitate the development of secondary neoplasms, related to the patient's impaired immunosurveillance.The surprisingly short latency between the therapy and the reappearance of non hematological cancers seen in our patients suggests that treatment with purine analogs may be involved in the reappearance of the tumors. In this regard, we suggest a possible role for purine analog-induced immunodeficiency in allowing the growth of previously undetected cancer cells rather than a direct drug-related muta-genic activity.

Crystal structures and properties of mutagenic N-acyloxy-N-alkoxyamides--"most pyramidal" acyclic amides.

X-Ray data for two N-acyloxy-N-alkoxyamides, a class of direct-acting mutagens, indicate extreme pyramidalisation at the amide nitrogen in keeping with spectroscopic and theoretically determined properties of amides with bisoxosubstitution at nitrogen. The combined electronegativity of two oxygens leads to average angles at nitrogen of 107.8 and 108.1 degrees and [chiN] of 66 degrees and 65 degrees. The sp3 nature of nitrogen results in negligible amide resonance as evidenced by long N-C(O) bonds, high IR carbonyl stretch frequencies, carbonyl 13C NMR data and very low amide isomerisation barriers. In addition, conformations in the solid state support a strong n(O)-sigma*(NOAc), anomeric interaction as predicted by molecular orbital theory. HF/6-31G* calculations on formamide, N-methoxyformamide and N-formyloxy-N-methoxyformamide support these findings.

Sensitive method for the determination of nitrated polycyclic aromatic hydrocarbons in the human diet.

The presence of nitrated polycyclic aromatic hydrocarbons (nitro-PAHs) as contaminants in foods is nowadays a legitimate cause of concern, as they are reported to be strong direct-acting mutagens and carcinogens that may pose a risk to human health. Nevertheless, their concentrations in foods are in the ultra-trace region. In this study, we present a very sensitive analytical method for the determination of this compound class in complex food matrices. Special emphasis was put on sample extraction and clean up. Recoveries of 75% could be obtained for 1- and 2-nitronaphthalene; for all other compounds investigated the recoveries were >/=94%. The determination of the compounds was performed by gas chromatography-mass spectrometry. The results show that the use of negative chemical ionization (NCI) increases the sensitivity by one order of magnitude in comparison to electron impact ionization (EI) (limits of detection 0.07-0.25 micro g kg(-1) for EI and 0.01-0.02 micro g kg(-1) for NCI). The influence of the sample matrix on the sensitivity of the method is demonstrated with extracts of a sample from a duplicate diet study. Due to the lack of a certified reference material the suitability of the method is demonstrated with pumpkin seed oil that was spiked with nitro-PAHs at two different concentration levels.

Comparative mutagenicity assessment of aerosols in emissions from biofuel combustion

This study was designed to determine the mutagenicity in extracts of aerosols generated from biofuel combustion in household cooking devices commonly used in India. Wood, dung cake and biofuel briquette were used as fuel in various stoves, including both traditional and improved stoves made of mud, fired clay and metal. The combustion aerosols of particle diameter less than 2.5 μm (PM2.5) were collected, and their organic extracts were tested for mutagenicity using the Ames Assay test with TA98 and TA100 strains of Salmonella typhimurium and studies were performed both with and without metabolic activation to account for direct and indirect acting mutagens. The measured mutagenicity emission factors, i.e., number of revertants per kg of fuel burnt, indicate that wood demonstrates significantly lower mutagenicity compared to dung cake and briquette. No significant stove effect was observed across all the fuels studied. The contribution of direct-acting mutagens was found to be greater than 70% in all cases. Such a high relative contribution of direct-acting mutagenicity has not been previously reported for biomass combustion aerosols.

The comet assay with MCL-5 cells as an indicator of genotoxic treatment with chemicals and cigarette smoke condensates.

The metabolically competent human lymphoblastoid cell line MCL-5 was treated with a panel of mutagens to assess the induction of DNA damage. Treatment effects were observed by monitoring cell proliferation and by single-cell gel electrophoresis (SCGE). The direct-acting mutagens benzo[a]pyrene-7,8-diol 9,10-epoxide (BPDE) and 1-methyl-3-nitro-1-nitrosoguanidine (MNNG), as well as pro-mutagens requiring metabolic activation, i.e. benzo[a]pyrene (BaP), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 4-N-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK), and cigarette-smoke condensate (CSC), were assayed by SCGE. Assay schemes were adapted for the MCL-5 cell line and for low levels of strand break induction, by inclusion of the DNA synthesis inhibitors cytosine arabinoside and hydyroxyurea, and by extending the electrophoresis time. For all mutagens tested, dose-dependent increases of median and average tail moment values among 50 nucleoids per slide were observed. The determining factors for selecting the treatment doses for mutation-induction experiments were the solubility of BaP and PhIP in the exposure medium, and the cytotoxicity exhibited by BPDE, MNNG and CSC. Induction of DNA strand breaks was obtained at mutagen concentrations permitting sufficient cell proliferation, except in the case of MNNG.

Antimutagenic activities of acetone and methanol fractions of Terminalia arjuna

The antimutagenic effect of benzene, chloroform, acetone and methanol fractions from Terminalia arjuna, a well-known medicinal plant, was determined against Acid Black dye, 2-aminofluorene (2AF) and 4-nitro- o-phenylenediamine (NPD) in TA98 Frameshift mutagen tester strain of Salmonella typhimurium. Among the different fractions, the antimutagenic effect of acetone and methanol fractions was more than that observed with other fractions. Co-incubation and pre-incubation modes of experimentation did not show much difference in the antimutagenic activity of the extracts. Moreover, these fractions inhibited the S9-dependent mutagens, 2AF and Acid Black dye more effectively than the direct-acting mutagens. Studies are under way to isolate and elucidate the nature of the antimutagenic factor in acetone and methanol fractions.

The in vitro antimutagenic activity of Triphala — an Indian herbal drug

A study to evaluate an antimutagenic potential of water, chloroform and acetone extracts of Triphala has been made in an Ames histidine reversion assay using TA98 and TA100 tester strains of Salmonella typhimurium against the direct-acting mutagens, 4-nitro- o-phenylenediamine (NPD) and sodium azide, and the indirect-acting promutagen, 2-aminofluorene (2AF), in the presence of phenobarbitone-induced rat hepatic S9. A combination drug ‘Triphala’ — a composite mixture of Terminalia bellerica, T. chebula and Emblica officinalis, has been used in traditional system of medicine for the treatment of many malaises, such as heart ailments and hepatic diseases. The drug was sequentially extracted with water, acetone and chloroform at room temperature. The study revealed that water extract was ineffective in reducing the revertants induced by the mutagens. The results with chloroform and acetone extracts showed inhibition of mutagenicity induced by both direct and S9-dependent mutagens. A significant inhibition of 98.7% was observed with acetone extract against the revertants induced by S9-dependent mutagen, 2AF, in co-incubation mode of treatment. Various spectroscopic techniques, namely 1H-NMR, normal 13C-NMR, distortionless enhancement by polarization transfer (DEPT-90 and DEPT-135), UV and IR, are under way to identify the polyphenolic compounds from an acetone extract.

Emission of polycyclic aromatic hydrocarbons, toxicity, and mutagenicity from domestic cooking using sawdust briquettes, wood, and kerosene.

Smoke samples, in both gas and particulate matter (PM) phases, of the three domestic stoves were collected using U.S. EPA modified method 5 and were analyzed for 17 PAH (HPLC-UV), acute toxicity (Microtox test), and mutagenicity (Amestest). The gas phase of smoke contributed > or = 95% of 17 PAH, > or = 96% of toxicity, and > or = 60% of mutagenicity. The highest emission factor of 17 PAH was from sawdust briquettes (260 mg/kg), but the highest emission of 11 genotoxic PAH was from kerosene (28 mg/kg). PM samples of kerosene smoke were not toxic. The total toxicity emission factor was the highest from sawdust, followed by kerosene and wood fuel. Smoke samples from the kerosene stove were not mutagenic. TA98 indicated the presence of both direct and indirect mutagenic activities in PM samples of sawdust and wood fuel but only direct mutagenic activities in the gas phase. TA100 detected only direct mutagenic activities in both PM and gas-phase samples. The higher mutagenicity emission factor was from wood fuel, 12 x 10(6) revertants/kg (TA100-S9) and 3.5 x 10(6) (TA98-S9), and lower from sawdust, 2.9 x 10(6) (TA100-S9) and 2.8 x 10(6) (TA98-S9). The low burning rate and high efficiency of a kerosene stove have resulted in the lowest PAH, toxicity, and mutagenicity emissions from daily cooking activities. The bioassays produced toxicity and mutagenicity results in correspondence with the PAH content of samples. The tests could be used for a quick assessment of potential health risks.

Modulatory Effect of Phenolic Fractions of Terminalia arjuna on the Mutagenicity in Ames Assay

We determined the antimutagenicity of phenolic fractions of Terminalia arjuna (soluble and insoluble in chloroform) against two direct-acting mutagens, 4-nitro-o-phenylenediamine (NPD) and sodium azide, and against the S9-dependent mutagen 2-aminofluorene (2AF), in TA98 and TA100 tester strains of Salmonella typhimurium. We found that the phenolic fractions of T. arjuna inhibited revertants induced by the S9-dependent mutagen more remarkably than the direct-acting mutagens. Furthermore, the phenolic fractions showed maximum inhibition of 98% and 101.55%, respectively, in the pre-incubation mode of treatment against the mutations induced by 2AF. Overall, the fractions inhibited the revertants induced by S9-dependent mutagens more effectively than those induced by direct-acting mutagens. The percentage of inhibition was higher in the pre-incubation than with direct acting mutagens. The fraction insoluble in chloroform showed more inhibition than the soluble one, which corresponds to a higher polyphenol content in the insoluble fraction than in the soluble extract.

A CORRELATIVE STUDY ON ANTIMUTAGENIC AND CHEMOPREVENTIVE ACTIVITY OF ACACIA AURICULIFORMIS A. CUNN. AND ACACIA NILOTICA (L.) WILLD. EX DEL

The present study provides a correlation of the antimutagenic and chemopreventive activity of the barks of two commonly observed plants viz. Acacia auriculiformis and Acacia nilotica. We used the Ames antimutagenicity assay and the mouse mammary gland organ culture (MMOC) model. The plants were extracted with organic solvents to obtain chloroform fractions and acetone extracts. The antimutagenic activity was determined in two different strains using both direct-acting [4-nitro-o-phenylenediamine (NPD) or sodium azide] and indirect-acting [2-aminofluorene (2AF)] mutagens. The anticarcinogenic activity was evaluated based on the development of preneoplastic lesions in response to the chemical carcinogen 7,12-dimethylbenz[a]anthracene (DMBA). The results showed that the activity resulting from the 2AF mutagen was selectively greater than the activity from the direct-acting mutagens. Moreover, in general, acetone extracts were more potent in suppressing mutagenesis than the chloroform extracts. The antimutagenicity results obtained with extracts using the 2AF – TA100 system were comparable to the chemopreventive results with DMBA-induced mammary lesions. The order of activity in both tests was A. nilotica > A. auriculiformis. These results exhibited a good correlation between the antimutagenesis assay and the MMOC model, suggesting that these plants may contain active chemopreventive agents.

Genotoxic activity of extractable organic matter from urban airborne particles in Shanghai, China

The aim of this research is to investigate the impact of air pollution on the population in Shanghai. The genotoxicity of extractable organic matter (EOM) from the air particles was investigated by the means of the Salmonella plate incorporation assay, rat hepatocyte unscheduled DNA repair assay, and mice micronuclei test. The airborne particles were collected in 13 locations during the summer of 1992 and winter of 1993. The crude extracts were fractionated by acid–base partitioning into acid, base and neutral fractions. The neutral fractions were further fractionated by resin–silica gel column chromatography into three subfractions. The induction of revertants with the crude extracts was higher in winter samples than in summer samples. Both indirect-acting and direct-acting mutagenicity were observed. The mutagenicity was detected with TA98, but was not detected with TA100. The mutagenic activity was the greatest in the acid, aromatic and polar fractions from summer samples. The fractions from the winter samples did not show clear differences. There was no substantial location-related variance in the mutagenic potencies of EOM, but substantial location- or time-related variances in the mutagenic potencies of the airborne particles per cubic meter air were found. While rat hepatocyte unscheduled DNA synthesis (UDS) assay revealed genotoxicity for all the samples, there was no big variance in the genotoxicity of the fractions. The mouse micronuclei test showed results similar to the UDS assay. The difference of locality did not have statistical significance.

Effect of petrochemical sludge concentrations on changes in mutagenic activity during soil bioremediation process

AbstractThe present study was performed to assess the effect of the petrochemical sludge application rate on the mutagenic activity (Ames test) of soil and the persistence of mutagenic activity during laboratory soil bioremediation process. Sludge‐soil systems were prepared at four different sludge application rates (1.25, 2.5, 5, and 10% w/w). Unamended soil was used as a control. Immediately following sludge application, in the absence or presence of S9, a linear correlation between sludge application rates and mutagenicity was found but differed significantly (p < 0.05) from the control system only at higher application rates (5 and 10% w/w). The direct mutagenicity of all systems decreases during the bioremediation process, and after a year of treatment only the 10% system induced a mutagenic response that was significantly different from the control system. On the other hand, an initial increase of the indirect mutagenicity was observed at all application rates. The time required for observing this increase was inversely proportional to the initial sludge concentration. After a year of treatment, the indirect mutagenicity of all sludge‐amended soils was not significantly different but was significantly different from the unamended soils. The persistence of the direct mutagenic activity of the sludge‐amended soils was related to the sludge concentration, whereas the indirect mutagenic persistence was related to the relationship between easily degradable hydrocarbons and polynuclear aromatic hydrocarbons concentration and independent from the initial application rate.

A study of 2,4,6-trinitrotoluene inhibition of benzo[a]pyrene uptake and activation in a microbial mutagenicity assay

A number of in vitro and in vivo studies have determined that binary and complex mixtures may interact to produce a toxicity that could not be predicted based on the individual chemicals. The present study was conducted with a binary mixture of model compounds to investigate possible interactions affecting their mutagenicity. The compounds included Benzo[a]pyrene (BAP), a polycyclic aromatic hydrocarbon that is an indirect-acting mutagen of great environmental concern, and 2,4,6-Trinitrotoluene (TNT), a nitro-aromatic compound that is a direct-acting mutagen frequently found as a soil contaminant at munitions sites. This study indicated that a binary mixture of BAP and TNT failed to induce the positive mutagenic response in Salmonella typhimurium strain TA98 characteristic of either compound alone. Spectrofluorometric analysis of BAP, and kinetic analyses of 3HBAP uptake in the presence or absence of TNT using TA98 cells that were treated or untreated with activated rat liver microsomes were performed. In cells preloaded with BAP, cellular BAP fluorescence was rapidly suppressed in the presence of TNT. Mass spectroscopy of BAP and TNT mixtures revealed a number of products, believed to be the result of complexation and nitration, that may account for the antagonistic action of TNT on BAP-induced mutagenicity in TA98 cells. Further, kinetic studies indicated that TNT inhibited the incorporation of BAP into cells.

Antimutagenicity and induction of anticarcinogenic phase II enzymes by basidiomycetes

Extracts from Phellinus linteus, Phellinus igniarius, and Agrocybe cylindracea have been tested for their antimutagenic properties against direct-acting mutagens {4-nitro- o-phenylenediamine (NPD) and sodium azide (NaN 3)} and indirect-acting mutagens {2-aminofluorene (2-AF) and benzo[a]pyrene (B[a]P)}, using the Salmonella typhimurium tester strains TA 98 and TA 100. In addition, the chemopreventive potentials of these extracts to induce NAD(P)H:quinone oxidoreductase (QR) and glutathione S-transferase (GST) activities and glutathione (GSH) level extracts from the filtrate of the cultured broth of P. linteus, polysaccharide extracts from the cultured broth (PI I) and mycelia (PI II) and water extract of fruiting bodies (PI II) of P. igniarius, and polysaccharide extracts from the cultured broth (AC I) and mycelia (AC II) of A. cylindracea showed inhibitory effects on the mutagenic activities induced by the direct-acting mutagens, NPD and NaN 3, and the indirect-acting mutagens, 2-AF and B[a]P. QR was induced with PI I, PI II, AC I, and AC II, and GST activity was induced with PL I, PL II, PI I, PI II, PI III and AC I in murine Hepa1c1c7 cell culture. In addition, PL I, PL II, PI I, PI II, PI III and AC II increased glutathione level. These results suggest that P. linteus, P. igniarius, and A. cylindracea have antimutagenic activities and may play a role in the prevention of cancer by inducing QR and GST activities and increasing GSH level.