Protective effect of S-allylcysteine and lycopene in combination against N-methyl-N'-nitro-N-nitrosoguanidine-induced genotoxicity

Chemoprotection by diet-derived antioxidants has emerged as a cost-effective approach in preventing genotoxicity and carcinogenicity. In this study, we investigated the protective effects of S-allylcysteine (SAC) and lycopene against N-methyl-N'-nitro-N-nitrosoguanidine (MNNG)-induced genotoxicity. Quantification of bone marrow micronuclei and chromosomal aberrations in male Wistar rats was used to monitor the protective effects of SAC and lycopene. Intragastric administration of MNNG (40 mg/kg) induced a significant increase in the frequency of micronuclei and chromosomal aberrations. Although pretreatment with SAC and lycopene significantly reduced the frequency of MNNG-induced bone marrow micronuclei and chromosomal aberrations, the combination of SAC and lycopene exerted a greater protective effect. These findings indicate that antioxidants such as SAC and lycopene, are effective chemoprotective agents against genotoxicity and carcinogenicity especially when used in combination.     

Re-examination of potassium sorbate and sodium sorbate for possible genotoxic potential

Potassium sorbate and sodium sorbate were investigated for possible genotoxic actions using the Salmonella/mammalian-microsome test, HGPRT and sister chromatid exchange (SCE) test with Chinese hamster ovary cells, the micronucleus test on bone marrow cells of mice and Chinese hamsters, and the chromosome aberration and SCE test on Chinese hamsters. In all the in vitro tests no signs of genotoxicity were detected. Whereas no in vivo mutagenicity of potassium sorbate and sodium sorbate with freshly prepared aqueous solutions and with stored potassium sorbate was found, investigations with stored sodium sorbate revealed weak clastogenic activity by increased chromosome aberrations and elevated numbers of micronuclei at doses of 200 mg/kg body weight, but no induction of SCEs.     

Cytotoxic and genotoxic effects of paraquat in Hordeum vulgare and human lymphocytes in vitro

Two phylogenetically distant types of test‐systems—root tip meristems of barley (Hordeum vulgare) and human lymphocytes in vitro were used to detect genotoxicity and cytotoxicity induced by the herbicide paraquat (PQ) in the concentration range (10^?6 to 5 × 10^?4 mol/l). As an endpoint for cytotoxicity the mitotic index (MI) was evaluated. The frequency of chromosome aberrations (CA) and the frequency of micronuclei (MN) were used as endpoints for genotoxicity. A dose‐dependent increase of CA and MN was observed in both test systems, although the values for PQ‐induced MN were somewhat lower. The increase of the genotoxic effect corresponds to a decrease of mitotic activity. The structurally reconstructed barley karyotype MK14/2034 allowed the allocation of the PQ‐specific features of aberration distribution patterns and gave information about which chromosome segments in different chromosomal positions were involved in induced aberrations. Paraquat produced preferably isochromatid breaks and “aberration hot spots” in a restricted number of heterochromatin‐containing segments. The comparative analysis of susceptibility in the used test‐systems to PQ with respect to its cytotoxic and clastogenic effect showed that the human lymphocytes were more sensitive than Hordeum vulgare. © 2009 Wiley Periodicals, Inc. Environ Toxicol, 2010.     

Genotoxicity evaluation for single‐walled carbon nanotubes in a battery of in vitro and in vivo assays

The genotoxicity of single‐walled carbon nanotubes (SWCNTs) was determined using a battery of genotoxicity assays, comprising a bacterial reverse mutation test, an in vitro mammalian chromosomal aberration test and a mammalian erythrocytes micronucleus test. SWCNTs had no mutagenicity in S. typhimurium TA98, TA100, TA1535 or TA1537, or in E. coli WP2uvrA, in the absence or presence of metabolic activation. SWCNTs did not increase the number of structural or numerical chromosomal aberrations after short‐term or continuous exposure. In the micronucleus test using CD‐1 mice, SWCNTs did not affect the proportion of immature erythrocytes, the total proportion of erythrocytes or the number of micronuclei in immature erythrocytes. SWCNTs appear not to pose a genotoxic risk. Copyright © 2012 John Wiley & Sons, Ltd.     

黄蜀葵花提取物金丝桃苷的急性毒性和遗传毒性评价(英文)

研究黄蜀葵花提取物金丝桃苷的急性毒性和遗传毒性,对其安全性进行评价。急性毒性试验中,选用健康BALB/c小鼠40只,雌雄各半,灌胃给药(5000mg/kg),连续观察14天,记录中毒和死亡情况,测定小鼠的半数致死量(LD50)。用目前新药遗传毒性评价中推荐使用的3种试验方法,营养缺陷型鼠伤寒沙门氏菌回复突变试验(Ames试验),中国仓鼠肺成纤维细胞(CHL)染色体畸变试验和小鼠骨髓微核试验研究金丝桃苷的遗传毒性。在急性毒性试验中,所有实验动物都存活,且行为活泼,未见明显异常。Ames试验中,金丝桃苷在加或不加肝微粒体酶(S9)时均未见引起TA97、TA98、TAl00和TAl02试验菌株基因突变(P>0.05)。体外CHL细胞染色体畸变试验中,金丝桃苷在加或不加S9时均未引起CHL细胞的染色体畸变(P>0.05)。小鼠微核试验中,金丝桃苷各剂量组小鼠骨髓多染红细胞微核率与阴性对照组相比,差异无统计学意义(P>0.05)。在本实验条件下,金丝桃苷对于BALB/c小鼠的LD50大于5000mg/kg,金丝桃苷没有遗传毒性。     

Evaluation of the genotoxic potential of single-wall carbon nanotubes by using a battery of in vitro and in vivo genotoxicity assays

The genotoxic potential of a high purity sample of single-wall carbon nanotubes (SWCNTs) was evaluated using a battery of in vitro and in vivo genotoxicity assays. These comprised a bacterial reverse mutation test (Ames test), an in vitro chromosomal aberration test, and an in vivo mouse bone marrow micronucleus test. The SWCNTs exerted no genotoxicity in Salmonella typhimurium TA97, TA98, TA100, and TA1535, or in Escherichia coli WP2 uvrA/pKM101, whether in the absence or presence of metabolic activation and at concentrations of 12.5–500 μg/plate. In the chromosomal aberration test, at 300–1000 μg/mL, the SWCNTs did not increase the number of structural or numerical chromosomal aberrations, whether the test was conducted with or without metabolic activation. In the in vivo bone marrow micronucleus test, doses of 60 mg/kg and 200 mg/kg SWCNTs did not affect the proportions of immature and total erythrocytes, nor did it increase the number of micronuclei in the immature erythrocytes of mice. The results of these studies show that the high purity and well-dispersed sample of SWCNTs are not genotoxic under the conditions of the in vitro bacterial reverse mutation assay, chromosomal aberration assay, or in vivo bone marrow micronucleus test, and thus appear not to pose a genotoxic risk to human health in vivo.     

Analysis of sister chromatid exchange, micronucleus and chromosomal aberration frequencies in rodents exposed to mosquito coil smoke by inhalation route

Mosquito coil smoke emitting from a mosquito repellent, was tested for its mutagenic effect in bone marrow cells from mouse and rat after 4 h acute inhalation exposure. Coil smoke with suspended particulate concentrations of 99–129 mg/m³, significantly elevated the frequencies of sister chromatid exchanges in bone marrow cells and micronuclei in polychromatic erythrocytes. Analysis of chromosomal aberrations in metaphases also revealed a significantly higher incidence of chromosomal aberration frequency in exposed rats and mice.     

Genotoxicity studies on licorice flavonoid oil (LFO)

Licorice flavonoid oil (LFO) is a new functional food ingredient. In this study, the genotoxicity of LFO was investigated using a test battery of three different methods. In a reverse mutation assay using four Salmonella typhimurium strains and Escherichia coli, LFO did not increase the number of revertant colonies in any tester strain with or without metabolic activation by rat liver S9 mix. In a chromosomal aberration test using Chinese hamster lung (CHL/IU) cells, LFO did not induce any chromosomal aberrations either in the short period test without rat liver S9 mix or in the continuous treatment (24 h or 48 h) test. However, in the short-period test with rat liver S9 mix, LFO induced structural chromosomal aberrations at concentrations higher than 0.6 mg/mL. A bone marrow micronucleus test using male F344 rats was initially conducted. The animals were dosed by oral gavage at doses up to 5000 mg/kg/day. No significant or dose-dependent increases in the frequency of micronucleated polychromatic erythrocytes (MNPCE) were observed and the high dose suppressed the ratio of polychromatic erythrocytes (PCE) to total erythrocytes. Subsequently, a liver and peripheral blood micronucleus test using male F344 rats was conducted. No micronuclei induction either in hepatocytes or PCE was observed even at the highest dose of 5000 mg/kg/day. From the findings obtained from the genotoxicity assays performed in this study and the published pharmacokinetic studies of LFO, it appears unlikely that dietary consumption of LFO will present any genotoxic hazard to humans.     

Evaluation of genotoxicity of multi-walled carbon nanotubes in a battery of in vitro and in vivo assays

The genotoxic potential of two products of multi-walled carbon nanotubes (coded as N-MWCNTs, diameter of 44 nm/BET surface area of 69 m²/g and MWNT-7, diameter of 70 nm/BET surface area of 23 m²/g) was evaluated using a battery of genotoxicity assays, comprising a bacterial reverse mutation test, an in vitro mammalian chromosomal aberration test, and a mammalian erythrocytes micronucleus test. Neither type exerted mutagenicity in Salmonella typhimurium TA98, TA100, TA1535, and TA1537, or in Escherichia coli WP2uvrA, in the absence or presence of metabolic activation. The products of MWCNTs did not increase the number of structural chromosomal aberrations either, regardless of metabolic activation, though they increased the number of numerical chromosomal aberrations, one slightly and the other distinctly, in the absence of metabolic activation. In ICR mice, the two products did not affect the proportion of immature erythrocytes, the total proportion of erythrocytes, or the number of micronuclei in immature erythrocytes.     

Genotoxicity of ibuprofen in mouse bone marrow cells in vivo

Genotoxicity of ibuprofen was evaluated by employing the mouse in vivo chromosomal aberration (CA) test. Ibuprofen administered orally at doses of 10, 20, 40, and 60?mg/kg body weight to mice resulted in mitotic depression and induction of CAs. A dose-related decrease in mitotic index (MI) and an increase in the frequencies of chromosomal aberrations per cell (CAs/cell) were recorded in bone marrow cells. However, a statistically significant reduction in MI and an increase in CAs/cell were found for both the higher doses. The results obtained indicate that ibuprofen is capable of inducing dose-dependent genotoxicity in bone marrow cells of mice.     

Pluchea lanceolata attenuates cadmium chloride induced oxidative stress and genotoxicity in Swiss albino mice

Cadmium intoxication induces lipid peroxidation and causes oxidative damage to various tissues by altering antioxidant defence system enzymes. At 24 h after treatment with a single intraperitoneal dose of cadmium chloride (5 mg kg-1), Swiss albino mice showed a significant increase in the levels of malanodialdehyde and xanthine oxidase (P<0.001), and a concomitant depletion of renal glutathione, catalase (P<0.001) and other antioxidant enzymes. CdCl2 also led to a simultaneous increase in micronuclei formation (P<0.001) and chromosomal aberrations (P<0.05) in mouse bone marrow cells. Oral pre-treatment with Pluchea lanceolata extract at doses of 100 and 200 mg kg-1 for 7 consecutive days before CdCl2 intoxication caused a significant reduction in malanodialdehyde formation and xanthine oxidase activity (P<0.001). A significant restoration of the activity of antioxidant defence system enzymes such as catalase, glutathione peroxidase (P<0.05), glutathione-S-transferase and glutathione reductase (P<0.001) was observed. A significant dose-dependent decrease in chromosomal aberrations and micronuclei formation was also observed (P<0.05). The results indicate that pre-treatment with P. lanceolata attenuates cadmium chloride induced oxidative stress and genotoxicity by altering antioxidant enzymes and reducing chromatid breaks and micronuclei formation.     

Effects of flavonol derivatives on the micronuclei formation by N-methyl-N′-nitro-N-nitrosoguanidine and the enhancement of bleomycin-induced chromosome aberration by N-methyl-N′-nitro-N-nitrosoguanidine

Flavonol derivatives were tested for their anticlastogenic effect against induction of micronuclei by N-methyl-N′-nitro-N-nitrosoguanidine(MNNG), and against induction of chromosome aberration by bleomycin or MNNG/bleomycin. For micronucleus assay, each flavonol derivative (0, 0.001, 0.01, 0.1, 1, 10 and 100 mg/kg) was administered orally twice with 24 h interval, together with intraperitoneally administered MNNG (150 mg/kg). The results showed that most flavonol derivatives tested were effective in suppressing the frequencies of micronuclei induced by MNNG. For chromosome aberration assay, each flavonol derivative (0, 0.1, 1, 10, and 100 mg/kg) was administered to mice orallyin vivo, and then mice were sacrificed and spleen lymphocyte cultures were made. Bleomycin (3 μg/ml) was treated to the mouse spleen lymphocyte cultures at 24 h after con A initiation. There were no marked decrease tendencies in chromosome aberration unless all doses of galangin and some doses of several flavonol derivatives tested. In the another experiment, we have evaluated the effect of flavonol derivatives on the enhancement of bleomycin-induced chromosome aberration by MNNG. Most of flavonol derivatives reduced the incidence of chromosome aberration induced by in vitro treatment of bleomycin followed byin vivo treatment of MNNG. Galangin particulary showed a dose-dependent decrease tendency. Other flavonol derivatives showed slightly decrease tendencies although there were no dose-dependent relationships. These results suggest that most of flavonol derivatives may be capable of protecting the inibition of DNA-repair by MNNG. Our data indicate clearly that flavonol derivatives can suppress MNNG-induced genotoxicity such as an induction of MNPCEs. Therefore, our results could suggest that flavonol derivatives may be useful as a chemopreventive agent of MNNG.     

Effect of temperature on the frequency of chromosome aberrations and micronuclei in cultured Chinese hamster cells

We previously reported that both hyperthermia and hypothermia induced micronuclei in mouse bone marrow cells (Asanami and Shimono, 1997a, 1997b, 1999). To investigate the effects of temperature on chromosome aberration in vitro, we conducted chromosome aberration and micronucleus tests under hyper- and hypothermic conditions using Chinese hamster lung (CHL) cells. In the chromosome aberration test, we observed positive responses at 40 degrees C and 41 degrees C for 24 hr, and at 42 degrees C for 6 hr and over. In the micronucleus test, we observed positive responses at 31 degrees C, 33 degrees C, and 40 degrees C for 24 hr, and at 42 degrees C for 2 hr. The results suggest that in CHL cells, hypothermic conditions can induce micronuclei while hyperthermic conditions can induce both chromosome aberrations and micronuclei.     

聚乙二醇修饰降纤酶的遗传毒性评价

目的检测聚乙二醇修饰降纤酶的遗传毒性。方法应用鼠伤寒沙门菌回复突变试验(Ames试验)、体外培养CHO细胞染色体畸变试验和小鼠骨髓微核试验检测聚乙二醇修饰降纤酶的遗传毒性。结果 Ames试验结果显示每平皿100、20、4、0.8、0.16 U各个剂量组,在加或不加S9代谢活化系统时对组氨酸缺陷型鼠伤寒沙门菌TA97、TA98、TA100、TA102及TA1535所诱发的回复突变菌落数均与溶剂对照的突变菌落数相近。体外培养CHO细胞染色体畸变试验结果显示2.5、5.0和10.0 U.mL-1各个剂量组在加S9代谢活化系统于24 h和不加S9代谢活化系统于24 h、48 h培养的CHO细胞染色体畸变率与溶剂对照组比较均无显著差异(P>0.05)。小鼠骨髓微核试验显示425、850、1700 U.kg-1各个剂量组对ICR小鼠的微核诱发率与溶剂对照组比较均无显著差异(P>0.05)。结论聚乙二醇修饰降纤酶对鼠伤寒沙门菌无致突变性,对哺乳动物培养细胞的染色体无致畸变作用,对ICR小鼠无诱发骨髓嗜多染红细胞微核的效应。表明聚乙二醇修饰降纤酶在本实验条件下无遗传毒性。     

Effect of genetic polymorphism of GSTM1 and GSTT1 genotypes on cytogenetic biomarkers among coaltar workers

Chromosomal aberrations (CAs) in peripheral blood lymphocytes and micronuclei (MN) in exfoliated buccal cells have been used for decades as cytogenetic biomarkers to investigate genotoxicity among occupationally or environmentally exposed population. In our study, we investigated the association of increased cytogenetic damage with genetic polymorphism in glutathione-S transferase genotypes among occupationally exposed 115 coaltar workers and 105 unexposed controls. We found higher mean value of chromosome aberrations (chromatid type-2.01 ± 1.76; chromosomal type-2.22 ± 1.73) and buccal micronuclei (BMN-7.10 ± 1.56) in exposed subjects when compared to referents (chromatid type-0.82 ± .51; chromosomal type-0.87 ± .54; BMN-5.09 ± 2.88). We observed that individuals having null genotype of GSTM1 and GSTT1 have significantly higher frequency of CAs and MN. Despite of small sample size, our findings suggest a significant association between polymorphism of glutathione-S transferase genotypes and cytogenetic biomarkers which are considered as early effects of genotoxic carcinogens.     

乙双吗啉的致突变作用

目的:研究乙双吗啉的遗传毒性.方法:乙双吗啉5,10和15 mg·kg~(-1),腹腔注射观察诱发的小鼠骨髓染色体/染色单体畸变;应用Ames试验观察对测试菌株TA97,TA98,TA100,TA102的诱变作用.结果:乙双吗啉显著诱发小鼠骨髓染色体/染色单体畸变,其诱发的畸变细胞率(ACF)显著增加(P<0.01);在不加S9条件下,乙双吗啉对TA98,TA102有一定的诱发回复突变的作用.结论:乙双吗啉是一种遗传毒物质.     

Aspect ratio has no effect on genotoxicity of multi-wall carbon nanotubes

Carbon nanotubes (CNTs) have specific physico-chemical and electrical properties that are useful for telecommunications, medicine, materials, manufacturing processes and the environmental and energy sectors. Yet, despite their many advantages, it is also important to determine whether CNTs may represent a hazard to the environment and human health. Like asbestos, the aspect ratio (length:diameter) and metal components of CNTs are known to have an effect on the toxicity of carbon nanotubes. Thus, to evaluate the toxic potential of CNTs in relation to their aspect ratio and metal contamination, in vivo and in vitro genotoxicity tests were conducted using high-aspect-ratio (diameter: 10–15 nm, length: ~10 μm) and low-aspect-ratio multi-wall carbon nanotubes (MWCNTs, diameter: 10–15 nm, length: ~150 nm) according to OECD test guidelines 471 (bacterial reverse mutation test), 473 (in vitro chromosome aberration test), and 474 (in vivo micronuclei test) with a good laboratory practice system. To determine the treatment concentration for all the tests, a solubility and dispersive test was performed, and a 1,2-dipalmitoyl-sn-glycero-3-phosphocholine (DPPC) solution found to be more suitable than distilled water. Neither the high- nor the low-aspect-ratio MWCNTs induced any genotoxicity in a bacterial reverse mutation test (~1,000 μg/plate), in vitro chromosome aberration test (without S9: ~6.25 μg/ml, with S9: ~50 μg/ml), or in vivo micronuclei test (~50 mg/kg). However, the high-aspect-ratio MWCNTs were found to be more toxic than the low-aspect-ratio MWCNTs. Thus, while high-aspect-ratio MWCNTs do not induce direct genotoxicity or metabolic activation–mediated genotoxicity, genotoxicity could still be induced indirectly through oxidative stress or inflammation.     

Cytogenetic effects of quinalphos in mice

The cytogenetic effect of quinalphos was studied in Swiss albino mice using the micronucleus test, bone marrow and germ cell chromosome assays and sperm morphology assay. Quinalphos at 5, 10 and 15 mg/kg body weight was administered orally to mice. Quinalphos induced micronuclei in the bone-marrow cells of mice and also caused a significant increase in chromosomal aberrations in bone-marrow cells (at 10 and 15 mg/kg body weight dose levels) and in germ cells (at all tested doses). A high incidence of abnormal sperms was also observed in mice treated with quinalphos.     

Genotoxicity evaluation of Isaria sinclairii (ISE) extract

The mutagenic potential Isaria sinclairii, a traditional Chinese medicine composed of the fruiting bodies of I. sinclairii and its parasitic host larva, was evaluated using short-term genotoxicity tests, namely, the Ames test, chromosome aberration (CA), and micronuclei (MN) tests. In a Salmonella typhimurium assay, I. sinclairii extract (ISE) did not produce any mutagenic response in the absence or presence of 59 mix with TA98, TA100, TA1535, and TA1537. In the chromosome aberration (CA) test, ISE induced no significant effect on Chinese hamster ovary (CHO) cells compared with control. In the MN test, no significant change in the occurrence of micronucleated polychromatic erythrocytes was observed in male ICR mice intraperitoneally administered ISE at doses of 15, 150, or 1500 mg/kg. These results indicate that ISE has no mutagenic potential in these in vitro and in vivo systems.     

Inhibition of benzo(a)pyrene induced lung adenoma by panax ginseng extract, EFLA400, in Swiss albino mice

In the present investigation the chemopreventive action of Panax ginseng extract, EFLA400, in Swiss albino mice has been evaluated. We used a 9-week medium term anticarcinogenicity test model of lung adenomas [Yun et al.1)]. Lung adenomas were induced by single subcutaneous injection in the subscapular region with 0.02 ml of benzo(a)pyrene (BP) (0.5 mg suspension in 1% aqueous gelatin) in newborn mice (less than 24 h old). Also chromosomal aberrations and micronuclei induction were evaluated in bone marrow cells. These genotoxicity end-points were compared with adenoma incidence at the same dose levels of BP and EFLA400. The oral administration of EFLA400 (10 mg/kg body weight) showed significant reduction in number of adenomas and weight of the lungs induced by BP. A significant reduction (p<0.001) in lung adenoma incidence in EFLA400-treated mice was observed as compared to the 68.3+/-2.96% lung adenoma incidence in BP-alone group. The inhibition rate was 72.05+/-1.36% in EFLA400-treated group with respect to the reference group (BP-alone group). However, tumor multiplicity was observed as 0.91+/-0.08 and 0.25+/-0.01 in BP alone and BP+EFLA400-treated groups respectively. In EFLA400-treated group significantly reduced frequencies of chromosomal aberrations and micronuclei induced by BP were observed. The results of the present investigation suggest the chemopreventive action and antimutagenic effect of EFLA400 in Swiss albino mice induced by BP in newborn mice.