Significant Mutagenic Activity Research Articles

Toxicological evaluation of a glycan preparation from an enzymatic hydrolysis of Saccharomyces cerevisiae

The aim of this paper was to provide a comprehensive toxicological and safety evaluation of a yeast cell wall preparation (YCWP) for use as an animal feed ingredient. The following toxicological assessments were carried out: the mutagenic activity was tested using the Ames’ Test in five Salmonella typhimurium strains; clastogenic activity was investigated using the mammalian micronucleus test in Swiss ICO OF1 (IOPS Caw) mice; genotoxic activity was assessed using the in vitro mammalian chromosomal aberration test in human lymphocytes; acute oral toxicity was tested by administration of a single dose of 2000 mg/kg BW. Eye and skin irritation were assessed in rabbits according to OECD guidelines; skin sensitivity was established in guinea pigs by means of the Buehler test, while acute dermal and inhalation studies in rats were further completed, also according to OECD guidelines. All conducted tests were considered valid under the experimental conditions. No significant mutagenic activity or genotoxic activity was observed, and it was concluded that the test article did not induce any clastogenic effect. YCWP was found to be mildly irritating to the eye, slightly irritating to the skin but was found to be non-sensitizing in the guinea pig. The acute oral, dermal and inhalation studies did not yield any evidence of gross toxicity or pharmacological effects.

Toxicological evaluation of an unextracted Aurantiochytrium limacinum biomass, a novel docosahexaenoic acid rich feed ingredient

The purpose of this paper was to evaluate the toxicological potential of a heterotrophically grown unextracted Aurantiochytrium limacinum biomass (AURA) when used as a food additive. The following toxicological assessments were conducted on this novel docosahexaenoic acid rich feed ingredient: Mutagenic activity was tested by means of the Ames’ test using five Salmonella typhimurium strains; clastogenic activity was investigated using the micronucleus test in male and female Sprague Dawley rats; genotoxic activity was assessed by means of the in vitro metaphase analysis tests in human lymphocytes; oral toxicity was tested by administration of AURA at various concentrations; eye and skin irritation was assessed in rabbits according to OECD guidelines; skin sensitivity was established in guinea pigs by means of the Buehler test. All conducted tests were considered valid under the experimental conditions. No significant mutagenic activity or clastogenic activity was observed. Genotoxic activity in human lymphocytes was not induced. Oral administration of 276 mg AURA/kg bw11administration is based on milligrams unextracted Aurantiochytrium limacinum biomass (AURA) of per kilogram body weight (bw) of animal. and 2000 mg AURA/kg bw resulted in no mortality or signs of acute toxicity. Daily administration of 1000 mg AURA/kg bw caused no mortality or biologically relevant signs of toxicity and was established as the No Observable Adverse Effect Level. AURA was also found to be a non-irritant for the eye and skin of the rabbit and was non-sensitizing to guinea pig skin.

Genotoxic evaluation of newly synthesized iminothiazolidinones.

The current study was designed to assess the potential toxicological effects of newly synthesized iminothiazolidinones by employing Ames Salmonella, Escherichia coli WP2, Zea mays seed germination, and random amplified polymorphic DNA (RAPD) assay systems. The bacterial tester strains S. typhimurium TA1535, TA1537, TA1538, TA98, TA100, and E. coli WP2 uvrA were chosen to test the direct gene mutation inducing capabilities of the test materials in prokaryotic systems and Z. mays seeds for determination of potential toxicological effects in eukaryotic systems. OPA-3 and OPA-6 primers were used in the RAPD analysis to determine genotoxic activities on the eukaryotic genomes. According to the results, none of the test materials showed significant mutagenic activity on the bacterial tester strains at the chosen concentrations. Additionally, none of the tested compounds showed inhibition of the germination of Z. mays seeds. In contrast, the RAPD analysis results were inconsistent with the bacterial reversion assays and the seed germination assay results. All test materials significantly changed the RAPD profiles for OPA-3; however, only compound 5 showed a significant change for OPA-6 when compared with the control groups. In conclusion, the newly synthesized iminothiazolidinone derivatives (C1-C5) were determined as potentially genotoxic compounds and they should be checked with multiple toxicology test systems before further studies to determine their actual use.

English

Considering the vast use of sweeteners by the Brazilian population and the constant need for toxicological studies of food additives, this study aimed to evaluate the cytotoxic and mutagenic potentials of the sodium saccharin and/or sodium cyclamate sweeteners in plant (Allium cepa) and animal (Mus musculus) test systems based on concentrations permitted by the Brazilian laws. In A. cepa, both the sweeteners individually and their combinations concentration and exposure time (ET: 48, 72 and 168 h) dependently exerted cytotoxic and mutagenic effects. Similarly, an increased in micronuclei formation was also observed by the sweeteners in peripheral blood cells in mice. More toxic effects were observed with the combination doses at 168 ET. There may be a synergistic effect and DNA damage with an increasing concentration and ET. In conclusion, the concentrations considered safe by the Brazilian laws had significant cytotoxic and mutagenic activity on the eukaryotic cells. Key words: Allium cepa, Mus musculus, sweeteners, toxicity.

In vitro mammalian mutagenicity of complex polycyclic aromatic hydrocarbon mixtures in contaminated soils.

This study employed an in vitro version of the lacZ transgenic rodent mutation assay to assess the mutagenicity of nonpolar neutral and semipolar aromatic soil fractions from 10 PAH-contaminated sites, and evaluated the assumption of dose additivity that is routinely employed to calculate the risk posed by PAH mixtures. Significant mutagenic activity was detected in all nonpolar neutral fractions, and 8 of 10 semipolar aromatic fractions (nonpolar > semipolar). Mutagenic activity of synthetic PAH mixtures that mimic the PAH content of the soils (i.e., 5-PAH or 16-PAH mix) were greater than that of the PAH-containing soil fractions, with 5-PAH mix >16-PAH-mix. Predictions of mutagenic activity, calculated as the sum of the contributions from the mutagenic mixture components, were all within 2-fold of the observed activity of the nonpolar neutral fractions, with one exception. Observed differences in mutagenic activity are likely the result of dynamic metabolic processes, involving a complex interplay of AhR agonsim and saturation of metabolic machinery by competitive inhibition of mixture components. The presence of hitherto unidentified polar compounds present in PAH-contaminated soils may also contribute to overall hazard; however, these compounds are generally not included in current contaminated site risk assessment protocols.

Mutagenic assessment of three synthetic pyridine-diaryl ketone derivatives

Nowadays, there are increasing numbers of studies about synthetic chemicals according to the supply demands of bioactive chemicals. The current study aims to investigate genotoxic potential of bioactive synthetic pyridine compounds, phenyl-3-pyridinylmethanone (1), p-tolyl-3-pyridinylmethanone (2), and 4-methoxyphenyl-3-pyridinylmethanone (3), using Ames/Salmonella and Escherichia coli WP2 bacterial reversion mutagenicity test systems. The mutant bacterial tester strains sodium azide-sensitive Salmonella typhimurium TA1535, 9-aminoacridine-sensitive S. typhimurium TA1537, and N-methyl-N'-nitro-N-nitrosoguanidine-sensitive E. coli WP2uvrA were used to detect the mutagenic potential of the test compounds. The results indicated that none of the test substances showed significant mutagenic activity on S. typhimurium TA1535, TA1537, and E. coli WP2uvrA bacterial strains up to 1 µg/plate concentrations.

In vitro toxic action potential of anti tuberculosis drugs and their combinations

Tuberculosis (TB) is one of the leading infectious causes of death due to single infectious agent after HIV/AIDS. Rifampicin (RIF), Isoniazid (INH), Ethambutol (EMB), Pyrazinamide (PZA) and/or their combinations are extensively prescribed to treat TB. Despite several therapeutic implications, these drugs also produce several toxic effects at cellular level. MTT assay and Ames test were adopted in this study for the determination of cytotoxic and mutagenic potential of these anti-TB drugs. Among all tested drugs, cytotoxic potential of RIF was strongest with highly significant decline (p<0.001) in cell numbers at the concentration of 250μg/ml with LC50 at 325μg/ml, while significant decline (p<0.01) in cell count was observed in INH treated group at the concentration 500μg/ml with LC50 at 1000μg/ml. Moreover, combination RIPE demonstrated significant reduction (p<0.01) in cell number at the concentration of 25–500–500–500μg/ml with LC50 at 60–1200–1200–1200μg/ml. It is apparent from the data that almost all drugs represented identical mutagenic pattern i.e., more significant results were achieved in TA100 with metabolic activation (+S9). RIF proved to be highly mutagenic of all tested drugs with significant mutagenicity (p<0.01) at 0.0525μg/plate against TA98 strain with S9. The combination RIPE exhibited highly significant mutagenic activity (p<0.01) at concentration 0.125–3–3–3μg/plate without S9, while addition of S9 resulted in similar activity at lower doses, i.e., 0.0525–1–1–1μg/plate. It was concluded from the data that all anti-TB drugs possess significant cytotoxic and mutagenic potential, especially in combination, making TB patient more vulnerable to cytotoxic and mutagenic effects of anti-TB drugs, which could produce further health complications in TB patients.

A pilot study on the DNA-protective, cytotoxic, and apoptosis-inducing properties of olive-leaf extracts

Leaves of olive trees are an abundant raw material in the Mediterranean basin. They contain large amounts of potentially useful phytochemicals and could play beneficial roles in health care. In the present study, the principal bioactive phenols in olive-leaf extracts (OLEs) have been identified and quantified, and their genotoxic/antigenotoxic, cytotoxic and apoptotic effects have been assessed. The Somatic Mutation and Recombination Test (SMART) in wing imaginal discs of Drosophila melanogaster has been performed to test the possible genotoxicity of overall OLE and the individual components oleuropein and luteolin at different concentrations. The same assay was able to detect antigenotoxic activity against hydrogen peroxide as oxidative genotoxicant. None of the extracts/phenols tested showed significant mutagenic activity. This fact, together with the antigenotoxic activity against H 2O 2 detected for all these extracts/phenols, confirmed the safety of OLE, oleuropein and luteolin in terms of DNA protection. HL60 human promyelocytic leukemia cells were used to assess the cytotoxic effects of the extracts/phenols. OLE, oleuropein and luteolin showed a dose-dependent cytotoxic effect with different IC50 (10 μl/ml, 170 μM, and 40 μM, respectively). DNA fragmentation patterns and cell staining with acridine orange and ethidium bromide indicated that the mechanism for the cytotoxic effect of OLE, oleuropein and luteolin was the apoptotic pathway, with DNA laddering and cytoplasmic and nuclear changes. These results could help explain the mechanism of action that underlies the beneficial effect of OLE, proposed as a nutraceutical in the prevention of human cancer.

Poly(ethylene imine) Nanocarriers Do Not Induce Mutations nor Oxidative DNA Damage in Vitro in MutaMouse FE1 Cells

Genotoxicity information on polymers used for gene delivery is scant, but of great concern, especially when developing polymeric nanocarriers as nonviral vector systems for cancer treatment. The genotoxicity of some engineered nanomaterials, e.g., metal oxides like ZnO, TiO₂, and CuO but also carbon based materials like carbon black or nanotubes, has commonly been related to oxidative stress, and subsequent inflammation. Recent studies of poly(ethylene imine) (PEI)-based polymers, important nonviral vector systems for pDNA and siRNA, might raise concerns because of their toxic effects dominated by cellular oxidative stress and inflammatory responses, similar to the mentioned effects of engineered nanoparticles. In this study, we employed a FE1-MutaMouse lung epithelial cell line based mutation assay to determine the genotoxicity of three PEI-based polymers and nanosized zinc oxide particles (NZO), all of which have previously been shown to trigger oxidative stress and inflammation. In addition, oxidative DNA damage (8-OH-dG) in FE1 cells was assessed by ELISA. The well-known carcinogen benzo[a]pyrene (B[a]P) was used as positive control. FE1 lung epithelial cells were exposed for eight sequential 72 h incubations, and reporter-gene mutation frequency or 8-OH-dG formation was determined to assess mutagenicity and oxidative DNA damage, respectively. No cytotoxic effects were detected at the exposure levels examined, which are representative of PEI concentrations normally used in in vitro transfection studies. In contrast to B[a]P, neither PEI-polymers nor NZO showed any significant mutagenic activity or oxidative DNA damage in the exposed cells, although PEI-based polymers have been shown to generate significant levels of cellular stress and inflammatory responses. We suggest that the lack of any detectable mutagenic/genotoxic activity of the PEI-based polymers studied here is a crucial step toward a safe use of such nanocarriers in clinical trials.

Mutagenicity of Hypericum lysimachioides extracts

Hypericum (Hypericaceae) species are extensively used in several fields such as traditional medicine, food and crop protection. Despite its usage in many fields, the identification of the genotoxic potential of this herb is still incomplete. In this study, we evaluated genotoxic effects of the petroleum ether, hexane, ethyl acetate, and methanol extract of Hypericum lysimachioides Boiss. var. lysimachioides by Ames Salmonella/microsome test and SOS chromotest. The mutagenic activity of Hypericum lysimachioides var. lysimachioides extracts was investigated by using Salmonella typhimurium strains TA98 and TA100 and also the SOS chromotest with Escherichia coli PQ37 strain, with or without S9 metabolic activation. In this initial report we demonstrated that all extracts of H. lysimachioides var. lysimachioides showed significant mutagenic activity on both strains of Salmonella either with or without S9 mixture. No mutagenicity was found in the SOS chromotest either with or without S9 mixture. These results indicate a significant mutagenicity of the petroleum ether, hexane, ethyl acetate and methanol extracts of Hypericum lysimachioides var. lysimachioides in vitro. It can be suggested that quercetin and flavonol or their synergistic effects may be main mutagenic agents in the photopharmaceuticals Hypericum lysimachioides var. lysimachioides extract.

Mutagenic activity of 1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine

MPTP (1-methyl-4-phenyl-1,2,3,6-tetrahydropyridine) is a neurotoxin, which can damage dopaminergic neurons. It causes symptoms resembling those observed in patients suffering from Parkinson's disease, and hence this toxin is widely used in studies on animal models of this disorder. Mutagenicity of MPTP was also reported by some authors, but results obtained by others suggested that this compound is not mutagenic. Interestingly, those contrasting results were based on the same assay (the Ames test). Therefore, we aimed to test MPTP mutagenicity by employing a recently developed Vibrio harveyi assay, which was demonstrated previously to be more sensitive than the Ames test, at least for some mutagens. We found that MPTP showed a significant mutagenic activity. Moreover, MPTP mutagenicity was attenuated by methylxanthines, compounds that are known to form complexes with aromatic mutagens.

Genotoxic and mutagenic activity of environmental air samples from different rural, urban and industrial sites in Flanders, Belgium

The present study reports mutagenic and genotoxic activities associated with ambient air collected at 15 sites characteristic for urban, industrial or rural conditions in Flanders. Airborne particulates (PM10) and semi-volatile compounds were collected on quartz filters (QF) and polyurethane foam (PUF) cartridges using a high-volume sampling device. The mutagenic and genotoxic potency of the organic extracts – Soxhlet extraction with acetone – was determined by use of the Salmonella mutagenicity standard plate-incorporation assay and the Vitotox ® assay, respectively. Concentrations of 16 polycyclic aromatic hydrocarbons (PAHs) in the extracts were determined by reversed-phase high-performance liquid chromatography (HPLC). Ambient air samples contained significant PAH levels and mutagenic activities at all 15 sites: direct mutagenicity of up to 47 revertants per cubic meter was found in the QF extracts and more limited activity of up to 11 rev m −3 in the PUF extracts. Metabolic activation of PUF extracts resulted in an important increase in mutagenic activity, up to 30 rev m −3, but no such increase was observed for QF extracts. The highest values were observed outside large cities at industrial sites and at a rural site contaminated by pollution from a chemical plant at a distance of 4 km. Also at the background location near the North Sea a significant mutagenic activity was measured in the QF extracts (+S9: 9 rev m −3; −S9: 7 rev m −3). Apparently, there is in Flanders a significant background exposure level to airborne mutagenicity, even in areas with limited or no nearby pollution sources. Based on the concentrations of 10 mutagenic PAHs and supposing additivity of their specific mutagenicities, only a few percent (mean 3%) of the observed indirect mutagenic activity could be explained. This implies that most mutagenic activity originated from other substances that were not identified or measured in our chemical analysis. This underscores the importance of bio-monitoring measurements.

Genotoxicity and antigenotoxicity of Origanum oil and carvacrol evaluated by Ames Salmonella/microsomal test

This study evaluates the genotoxic and antigenotoxic effects of the essential oil of Origanum onites L. and carvacrol that are used in medicine, flavouring of food and crop protection by Ames Salmonella/microsomal test. The mutagenic activity was initially screened using Salmonella typhimurium strains TA98 and TA100, with or without S9 metabolic activation. No mutagenicity was found in the oil to the both strains either with or without S9 mixture whereas significant mutagenic activity was induced by carvacrol generally in the absent of metabolic activity. The oil and its major constituent carvacrol were finally tested for their antimutagenic activity with 30 min standard preincubation time. It was shown that both of them strongly inhibited mutagenicity induced by 4-nitro- o-phenylenediamine and 2-aminofluorene in both strains with or without S9, respectively. These results indicate significant antimutagenicity of the essential oil and carvacrol in vitro, suggesting its pharmacological importance for the prevention of cancer.

Mutagenicity of benzo[ b]phenanthro[2,3-d]thiophene (BPT) and its metabolites in TA100 and base-specific tester strains (TA7001–TA7006) of Salmonella typhimurium: evidence of multiple pathways for the bioactivation of BPT

Benzo[ b]phenanthro[2,3-d]thiophene (BPT), and a number of its metabolites, including BPT-3,4-diol, BPT sulfoxide, BPT sulfone, and 3-hydroxyBPT were assessed for their mutagenic activity in Salmonella typhimurium strain TA100, and S. typhimurium base-specific strains TA7001, TA7002, TA7003, TA7004, TA7005, and TA7006. Among the compounds tested in strain TA100, BPT, BPT sulfone, and 3-hydroxyBPT did not show any significant mutagenic response in the presence of S9. In contrast BPT sulfoxide and BPT-3,4-diol (a precursor to the bay-region diol epoxide of BPT) showed significant mutagenic activity in the presence of S9. Surprisingly, BPT sulfoxide was nearly 3.3-fold more mutagenic than BPT-3,4-diol in the presence of S9. BPT sulfoxide also displayed intrinsic mutagenic activity, which was nearly 1.5-fold less than that displayed by BPT-3,4-diol in the presence of S9. In base specific tester strains, BPT sulfoxide was the most active metabolite in strains TA7002, TA7004, and TA7005 with S9 activation. In these strains, BPT-3,4-diol was 2- to 7-fold less mutagenic than BPT sulfoxide in the presence of S9. Only in strain TA7006, BPT-3,4-diol was four-fold more mutagenic than BPT sulfoxide. The fact that BPT sulfoxide is significantly more mutagenic than BPT-3,4-diol in S. typhimurium strain TA100 suggests that the formation of sulfoxide may be the principal pathway for the metabolic activation of BPT to mutagenic products. Based on the results from Tester Strain TA7005, it indicate that BPT and its most mutagenic metabolite BPT sulfoxide induce predominantly CG → AT transversion, which is observed as the most frequent base substitution mutation of p53 tumor-suppressor gene in human lung cancer.

Toxicological profile of pollutants in surface water from an area in Taihu Lake, Yangtze Delta

The environment in urbanized areas is often contaminated with a complex mixture of toxic compounds originating from industries, agriculture and private households. Most of the contaminants end up in surface waters, such as lakes, rivers and finally the sea. Toxic contaminants may disturb the biological condition of aquatic ecosystems and be harmful for humans, if they are transported to human food or drinking water. A variety of biological tests have been introduced for monitoring the toxicological profile of aquatic ecosystems. In the present investigation, genotoxic, hormone disrupting and Ah-receptor activity was analyzed in water collected in January 1999 at Meiliang Bay, Taihu Lake, China, near to the city of Wuxi in the Shanghai area. Significant mutagenic activity could be detected in water extracts with the Salmonella/microsome assay and the arabinose resistance test. Frame shift mutations were the predominant mode of action. Ah-receptor active compounds were detected by using a luciferase reporter gene assay (CALUX-assay). The estimated toxic equivalent factor-values ranged between 134 and 232 pg TCCD-equivalents per liter lake water. The estrogen-like potential of Taihu water was estimated with two luciferase reporter gene assays using transgenic human cell lines expressing estrogen receptor alpha. Estradiol equivalents obtained with water extracts were in the range of 2.2–12.1 ng/l. We also analyzed the concentrations of 17-β-estradiol and ethinylestradiol in the extracts using a high-pressure liquid chromatography-method. The values obtained correlated with the biologically determined estradiol equivalents, indicating that the estrogenic activity is mainly due to natural and synthetic hormones rather than xenoestrogens.

Mutagenicity and cytotoxicity of fruits and vegetables evaluated by the Ames test and 3-(4,5-dimethylthiazol-2-yl)- 2,5-diphenyltetrazolium bromide (MTT) assay / Mutagenicidad y citotoxicidad de frutas y vegetales evaluadas por el test de Ames y el ensayo del bromuro de 3-(4,5-dimetiltiazol-2-il)-2,5-difeniltetrazolio (MTT)

The mutagenic and cytotoxic activity of the aqueous (H2O) and ethanolic (EtOH) extracts of fruits and vegetables were studied by the Ames test and the MTT assay. A significant mutagenic activity was found for three H2O extracts of broccoli ( Brassica oleracea), carrot ( Dacus carota) and licorice ( Glycyrrhiza glabra) and for one EtOH extract of kiwi ( Ananas sativus ) of the nine species analyzed. The frameshift tester strain TA98 was reverted by broccoli (2.4, 4.8 and 9.6 mg/mL; p &lt; 0.01) and carrot (9.6 mg/mL; p &lt; 0.001) aqueous extracts and by kiwi (9.6 mg/mL; p &lt; 0.0001) EtOH extract, whereas strain TA100 was only sensitive to the mutagens of licorice H,O extract, within the nine fruits and vegetables tested. The mutagenic response of the extracts was not altered by the presence of S9 mix. Cytotoxicity was only found for three of the nine species tested. Percentage cytotoxic ac tivities at 4.8 mg/mL in pineapple ( Actinidin diasinensis) and garlic ( Allium sativum) H,O extracts were 77 and 91 %, respectively. Licorice EtOH extract was the only one that showed a cytotoxic activity at all of the concentrations used. The percentage of cytotoxic activity of licorice extract was 63% at 0.24 mg/mL and increased with increasing concentration of licorice up to 4.8 mg/mL. Thus, licorice (EtOH) extract was the most cytotoxic of the species tested.

In vitro mutagenicity and genotoxicity study of a number of short-chain chlorinated hydrocarbons using the micronudeus test and the alkaline single cell gel electrophoresis technique (Comet assay) in human lymphocytes: a structure–activity relationship (QSAR) analysis of the genotoxic and cytotoxic potential

Using the micronucleus (MN) test and the alkaline single cell gel electrophoresis (Comet) assay, potential mutagenicity (MN formation), genotoxicity (DNA breakage capacity) and cytotoxicity (cell proliferation reduction) of five chlorinated hydrocarbons (carbon tetrachloride, hexachloroethane, 1,2-dichloroethane, 1-chlorohexane and 2,3-dichlorobutane) have been evaluated in isolated human lymphocytes. With the MN test a low but statistically significant mutagenic activity was detected for all tested substances (except 2,3-dichlorobutane) with one out of the two donors and in the presence or absence of an exogenous metabolic activation system (S9 mix). However, at the concentration ranges tested none of the positive compounds induced a clear dose-dependent mutagenic effect. The Comet assay detected a strong DNA damaging effect for 1-chlorohexane, 2,3-dichlorobutane and 1,2-dichloroethane, but not for carbon tetrachloride and hexachloroethane. The influence of metabolism on the genotoxic activity of the chemicals was more clear in the Comet assay than in the MN test. The experimental genotoxicity and cytotoxicity data obtained in this study, together with data on five more related chemicals previously investigated, and their physico-chemical descriptors or electronic parameters have been used for QSAR analysis. The QSAR analysis high-lighted that the toxicity of the tested compounds was influenced by different parameters, like lipophilicity (logP), electron donor ability (charge) and longest carbon-chlorine (LBC-Cl) bond length. In addition, steric parameters, like molar refractivity (MR) and LBC-Cl, and electronic parameters, like ELUMO (energy of the lowest unoccupied molecular orbital, indicating electrophilicity), were predominant factors discriminating genotoxins from non-genotoxins in the presence but not in the absence of S9 mix. Although a limited number of compounds have been examined and cytotoxicity and genotoxicity were identified in two different bioassay tests, the data set was obtained by the same experimentor, strengthening the reliability of the QSAR.

In vitro mutagenicity and genotoxicity study of 1,2-dichloroethylene, 1,1,2-trichloroethane, 1,3-dichloropropane, 1,2,3-trichloropropane and 1,1,3-trichloropropene, using the micronucleus test and the alkaline single cell gel electrophoresis technique (comet assay) in human lymphocytes

The main objective of this study was to compare the cytotoxic genotoxic and mutagenic activity of a number of chlorinated aliphatic hydrocarbons, which are widely used as chemical intermediates, solvents, degreasing agents etc. in industry, and to establish the structure-toxicity relationship of the chemicals by using the most adequate determinants in estimating their toxicity. The mutagenicity and cytotoxicity of some of the candidate chemicals, namely 1,2-dichloroethylene, 1,1,2-trichloroethane, 1,3-dichloropropane, 1,2,3-trichloropropane and 1,1,3-trichloropropene were evaluated in an in vitro micronucleus assay. The cytokinesis-block methodology was applied on human lymphocytes in the presence or absence of an external metabolic activation system (S9-mix). In the micronucleus assay, all test substances, except 1,2,3-trichloropropane with and without S9-mix and 1,1,2-trichloroethane without S9-mix in the repeated experiment, exhibited a low but statistically significant mutagenic activity, compared to the concurrent control. However, none of the five chemicals was able to induce a clear and reproducible linear dose-dependent increase in micronucleus frequencies in this assay. Generally, mutagenic activity of the chemicals was found in the absence of severe cytotoxicity and/or cell cycle delay. The DNA breakage capacity and the cytotoxicity of these chemicals were also assessed in the alkaline single cell gel (SCG) electrophoresis test (comet assay) with and without S9-mix in isolated human lymphocytes. All chemical compounds induced DNA breakage, in the presence or absence of the metabolic activation system, at the doses tested. The data showed that the DNA reactivity of the chemicals increased with increasing degree of halogenation. The results of the present work suggested that the comet assay might be a more suitable and sensitive screening method than the micronucleus test for this particular class of compound. However, both assays do detect different endpoints.

Mutagenic Activity (Ames Test) of Wood-Preserving Waste Sludge Applied to Soil

In both laboratory (McGinnis et al. 1988; Aprill et al. 1990) and field soiltreatability studies (Brown et al. 1985a), the majority of hazardousconstituents present in creosote/pentachlorophenol (PCP) bottomsediment sludges have been rendered less toxic after undergoingdegradation or transformation.However, the present investigators,utilizing the Ames test to monitor potential detoxification of creosote/PCPsludge constituents during field land treatment studies, observed apersistent mutagenic residue remaining in surface soil a year or moreafter the sludge was applied (Donnelly et al. 1987; Barbee et al. 1992).Not surprisingly therefore, surface runoff from soils amended withcreosote/PCP bottom sediment sludge also displayed significant levels ofAmes test mutagenic activity even 360 days after sludge application(Davol et al. 1989). It was estimated that three or more years would berequired for the mutagenic activity of runoff water discharging from landtreated sludge to return to background levels. In addition, after one yearof treatment water soluble fractions and leachate extracted from acreosote sludge/soil mixture produced a toxic response in the Microtox

Imidazole derivatives. XXVII. Synthesis and radioprotective activity of substituted phenacylthioimidazoline and 3-phenyl-5,6-dihydroimidazo[2,1-B]thiazole hydrochlorides

Previously, we described the synthesis of phenacylthioimidazolines and investigated the biological properties of the corresponding hydrochlorides. It was found that some hydorchlorides exhibited quite significant sympathicolytic and mutagenic activity. Due to the low solubility of substituted phenacylthioimidazoline hydrobromides in water and the fact that they can cyclize into imidazothiazoles it was difficult to convert the hydrobromides to the corresponding hydrochlorides. For this reason the phenacylthioimidazoline hydrochlorides were synthesized in the present work by reacting the phenacyl chlorides with 2-thio-2-imidazoline. 8 refs., 2 figs., 2 tabs.