The micronucleus assay with mouse peripheral blood reticulocytes using acridine orange-coated slides

Effects of lutein and chlorophyll b on GSH depletion and DNA damage induced by cisplatin in vivo

Recent studies have proposed the use of low concentrations of phytochemicals and combinations of phytochemicals in chemoprevention to reduce cytotoxicity and simulate normal ingestion through diet. The purpose of the present study was to evaluate whether the DNA damage, chromosome instability, and oxidative stress induced by cisplatin (cDDP) are modulated by a combination of the natural pigments lutein (LT) and chlorophyll b (CLb). The protective effects observed for synergism between phytochemicals have not been completely investigated. The comet assay and micronucleus test were performed and the catalase activities and glutathione (GSH) concentrations were measured in the peripheral blood, bone marrow, liver, and kidney cells of mice. The comet assay and micronucleus test results revealed that the pigments LT and CLb were not genotoxic or mutagenic and that the pigments presented antigenotoxic and antimutagenic effects in the different cell types evaluated. This protective effect is likely related to antioxidant properties in peripheral blood cells through the prevention of cDDP-induced GSH depletion. Altogether our results show that the combination of LT and CLb, which are both usually present in the same foods, such as leafy green vegetables, can be used safely.

Antigenotoxic effects of (-)-epigallocatechin-3-gallate (EGCG), quercetin, and rutin on chromium trioxide-induced micronuclei in the polychromatic erythrocytes of mouse peripheral blood

This study was conducted to investigate the modulating effects of (-)-epigallocatechin-3-gallate (EGCG), quercetin, and rutin on the genotoxic damage induced by Cr(VI) in polychromatic erythrocytes of CD-1 mice. The animals were divided into the following groups: (i) vehicle only; (ii) flavonoids (10 mg/kg EGCG, 100 mg/kg quercetin, 625 mg/kg rutin, or 100-625 mg/kg quercetin-rutin); (iii) Cr(VI) (20 mg/kg of CrO3); and (iv) flavonoids concomitantly with Cr(VI). All of the treatments were administered intraperitoneally (i.p.). The genotoxic damage was evaluated based on the number of micronucleated polychromatic erythrocytes (MN-PCE) obtained from the caudal vein 0, 24, 48, and 72 h after treatment. Groups treated with EGCG and quercetin exhibited no significant statistical changes in induction of MN-PCE. However, CrO3 treatment significantly increased MN-PCE induction 24 and 48 h after injection. Treatment with flavonoids prior to CrO3 exposure decreased MN-PCE induction compared with CrO3 only. The magnitudes of the potency of flavonoids were in the following order: rutin (82%) > quercetin (64%) > quercetin-rutin (59%) and EGCG (44%). The group treated with rutin significantly reduced genotoxic damage in mice treated with Cr(VI) (antioxidant effect). However rutin exerted a marginal genotoxic effect when administered alone (pro-oxidant effect). Our findings suggest protective effects of EGCG, quercetin, and rutin against genotoxic damage induced by Cr(VI).

Inhibitory effect of a propolis on di-n-propyl disulfide or n-hexyl salycilate-induced skin irritation, oxidative stress and inflammatory responses in mice

PURPOSE

Thermal imaging has been utilised, both preclinically and clinically, as a tool for assessing inflammation. Psoriasis is a chronic inflammatory skin disease characterised by hyperkeratosis, dermal inflammatory infiltrate and increased angiogenesis. The aim of the present study was to assess the usefulness of thermography in psoriatic lesion regression after topical treatment with bee propolis, recognised as potent antioxidants and anti-inflammatory agents.

METHODS

We monitored the inflammation process induced by irritants such as n-Hexyl salycilate (HXS) or Di-n-Propyl Disulfide (PPD) by histopatological assessment of the skin, thermographic scanning, total number of inflammatory cells in the peritoneal cavity, differential analysis of cells in the peritoneal cavity, macrophage spreading index, haematological and biochemical parameters, frequencies of micronucleated reticulocytes, lipid peroxidation and glutathione assay in the skin.

RESULTS

Topically applied ethanolic extract of propolis (EEP) with HXS or PPD reduced the lipid peroxidation in the skin and total number of inflammatory cells in the skin and peritoneal cavity, functional activity of macrophages, the number of micronuclei in mouse peripheral blood reticulocytes and enzymatic activity of ALP and AST.

CONCLUSION

These results demonstrate that topical application of EEP may improve psoriatic-like skin lesions by suppressing functional activity of macrophages and ROS production. Taken together, it is suggested that EEP can safely be utilised in the prevention of psoriasis-related inflammatory changes without causing any toxic effect.

Gestational exposure to Byrsonima verbascifolia: teratogenicity, mutagenicity and immunomodulation evaluation in female Swiss mice

ETHNOPHARMACOLOGICAL RELEVANCE

Byrsonima verbascifolia is used in folk medicine to treat diarrhea, intestinal infections, chronic wounds, Chagas disease, inflammation and as a diuretic. However there is no investigation regarding the Byrsonima verbascifolia hydrometanolic extract (BVHME) used during gestation.

MATERIALS AND METHODS

The pregnant females were randomly divided into 5 groups. Control group received saline plus DMSO (1%) in a volume of 0.1 mL/10 g (b.w.), via gavage, for at least 15 days prior to mating and throughout the gestational period. The Pre-treatment group received the BVHME, via gavage, at a dose of 50 mg/kg (b.w.) for at least 15 days prior to mating and up to the appearance of the vaginal plug. The Organogenesis group received the BVHME at a dose of 50 mg/kg (b.w.), via gavage, on the 5-15th gestational day. The Gestational group received the BVHME at a dose of 50 mg/kg (b.w.), via gavage, throughout the gestational period (from the 1st to the 18th day of pregnancy). The Pre+Gestational group received the BVHME at a dose of 50mg/kg (b.w.), via gavage, for at least 15 days prior to mating and up to throughout the gestational period. The clinical signals of maternal and fetuses toxicity were evaluated, as the mutagenicity and immunomodulation tests were performed.

RESULTS AND CONCLUSIONS

The present investigation shows, for the first time, that the use of Byrsonima verbascifolia extract in pregnant Swiss mice, did not alter the female reproductive function, mutagenicity or immunostimulation as well as not interfere with embryofetal development at least in our experimental conditions.

Lipid peroxidation, detoxification capacity, and genome damage in mice after transplacental exposure to pharmaceutical drugs

Data on genome damage, lipid peroxidation, and levels of glutathione peroxidase (GPX) in newborns after transplacental exposure to xenobiotics are rare and insufficient for risk assessment. The aim of the current study was to analyze, in an animal model, transplacental genotoxicity, lipid peroxidation, and detoxification disturbances caused by the following drugs commonly prescribed to pregnant women: paracetamol, fluconazole, 5-nitrofurantoin, and sodium valproate. Genome damage in dams and their newborn pups transplacentally exposed to these drugs was investigated using the in vivo micronucleus (MN) assay. The drugs were administered to dams intraperitoneally in three consecutive daily doses between days 12 and 14 of pregnancy. The results were correlated, with detoxification capacity of the newborn pups measured by the levels of GPX in blood and lipid peroxidation in liver measured by malondialdehyde (HPLC-MDA) levels. Sodium valproate and 5-nitrofurantoin significantly increased MN frequency in pregnant dams. A significant increase in the MN frequency of newborn pups was detected for all drugs tested. This paper also provides reference levels of MDA in newborn pups, according to which all drugs tested significantly lowered MDA levels of newborn pups, while blood GPX activity dropped significantly only after exposure to paracetamol. The GPX reduction reflected systemic oxidative stress, which is known to occur with paracetamol treatment. The reduction of MDA in the liver is suggested to be an unspecific metabolic reaction to the drugs that express cytotoxic, in particular hepatotoxic, effects associated with oxidative stress and lipid peroxidation.

Antigenotoxic and apoptotic activity of green tea polyphenol extracts on hexavalent chromium-induced DNA damage in peripheral blood of CD-1 mice: analysis with differential acridine orange/ethidium bromide staining

This study was conducted to investigate the modulating effects of green tea polyphenols on genotoxic damage and apoptotic activity induced by hexavalent chromium [Cr (VI)] in CD-1 mice. Animals were divided into the following groups: (i) injected with vehicle; (ii) treated with green tea polyphenols (30 mg/kg) via gavage; (iii) injected with CrO₃ (20 mg/kg) intraperitoneally; (iv) treated with green tea polyphenols in addition to CrO₃. Genotoxic damage was evaluated by examining micronucleated polychromatic erythrocytes (MN-PCEs) obtained from peripheral blood at 0, 24, 48, and 72 h after treatment. Induction of apoptosis and cell viability were assessed by differential acridine orange/ethidium bromide (AO/EB) staining. Treatment of green tea polyphenols led to no significant changes in the MN-PCEs. However, CrO₃ treatment significantly increased MN-PCEs at 24 and 48 h after injection. Green tea polyphenols treatment prior to CrO₃ injection led to a decrease in MN-PCEs compared to the group treated with CrO₃ only. The average of apoptotic cells was increased at 48 h after treatment compared to control mice, suggesting that apoptosis could contribute to eliminate the DNA damaged cells induced by Cr (VI). Our findings support the proposed protective effects of green tea polyphenols against the genotoxic damage induced by Cr (VI).

Induction of micronucleus of Oreochromis niloticus exposed to waters from the Cubatão do Sul River, southern Brazil

In an effort to characterize the pollution of surface waters by potentially genotoxic agents, this study aimed at assessing the frequency of micronucleated (MN) erythrocytes of the fish species, Oreochromis niloticus, from the Cubatão do Sul River. This river is the source of drinking water for the region of Florianópolis, capital of Santa Catarina State, Brazil. Negative control fish showed low frequency of MN, ranging between 0.49‰ and 0.90‰. Positive control (potassium dichromate 2.5 mg/L) organisms showed high MN frequency (16.82-17.25‰). The MN frequency increased along the river (Site 1--1.24‰ winter 2011; Site 4--9.76‰ summer 2011). Based on the observation of elevated MN erythrocytes frequency in O. niloticus exposed to water samples from along the river course, we conclude that the complex environmental mixtures of water from the Cubatão do Sul River have genotoxic potential. This genotoxicity most likely originated from agricultural runoff and domestic effluents released without treatment, based on the evidence from literature data and a survey in the region. This study provides a scientific basis for future studies regarding the genotoxicity of complex environmental mixtures in natural environments.

Structure analysis and antimutagenic activity of a novel salt-soluble polysaccharide from Auricularia polytricha

BACKGROUND

Auricularia polytricha is known to be a highly nutritious foodstuff. We report here the purification, structure characterization and antimutagenic activity in vivo of a 0.9% NaCl solution-soluble polysaccharide (SSP) from the mycelia of A. polytricha.

RESULTS

Analysis by high-performance liquid chromatography coupled to a TSK-G5000PWXL column and gel filtration chromatography on Sephacryl S-400 HR indicated that SSP is homogeneous with an average molecular weight of about 9.30 × 10(5) Da. The structure of SSP was revealed by chemical methods, Fourier transform infrared spectroscopy and nuclear magnetic resonance spectroscopy. Results indicated that SSP is a glucan consisting of a1,3-β-glucan, 1,6-α-glucan, 1,4-α-glucan and 1,3-α-glucan backbone with a single 1,6-α-d-glucopyranosyl side-branching unit on every nine residues, on average, along the main chain. Atomic force microscopy indicates the presence of macromolecular species in morphology and shows a clear association of prolate particle. Meanwhile, SSP was found to significantly preventing micronuclei in polychromatic erythrocytes and reticulocytes of mice (P < 0.01).

CONCLUSION

These results indicate that polysaccharide SSP from A. polytricha exhibits antimutagenic activity against the in vivo DNA-damaging effect of the indirectly acting alkylating agent cyclophosphamide.

Radioprotective effects of gallic acid in mice

Radioprotecting ability of the natural polyphenol, gallic acid (3,4,5-trihydroxybenzoic acid, GA), was investigated in Swiss albino mice. Oral administration of GA (100 mg/kg body weight), one hour prior to whole body gamma radiation exposure (2–8 Gy; 6 animals/group), reduced the radiation-induced cellular DNA damage in mouse peripheral blood leukocytes, bone marrow cells, and spleenocytes as revealed by comet assay. The GA administration also prevented the radiation-induced decrease in the levels of the antioxidant enzyme, glutathione peroxidise (GPx), and nonprotein thiol glutathione (GSH) and inhibited the peroxidation of membrane lipids in these animals. Exposure of mice to whole body gamma radiation also caused the formation of micronuclei in blood reticulocytes and chromosomal aberrations in bone marrow cells, and the administration of GA resulted in the inhibition of micronucleus formation and chromosomal aberrations. In irradiated animals, administration of GA elicited an enhancement in the rate of DNA repair process and a significant increase in endogenous spleen colony formation. The administration of GA also prevented the radiation-induced weight loss and mortality in animals (10 animals/group) exposed to lethal dose (10 Gy) of gamma radiation. (For every experiment unirradiated animals without GA administration were taken as normal control; specific dose (Gy) irradiated animals without GA administration serve as radiation control; and unirradiated GA treated animals were taken as drug alone control).

Assessment of the cytotoxic, genotoxic, and antigenotoxic activities of Celtis iguanaea (Jacq.) in mice

Ethnobotanical surveys of Cerrado native plants show that leaves of Celtis iguanaea (Jacq.) Sargent (Cannabaceae), popularly known in Brazil as "esporão de galo", are used in folk medicine for body pain, asthma, cramps, poor digestion, urinary infection, kidney dysfunctions, as well as a stimulant and diuretic. This work aimed at evaluating possible C. iguanaea aqueous leaf extract (CALE) cytotoxicity, genotoxicity, and antigenotoxicity using the mouse bone marrow micronucleous test. To assess CALE genotoxicity, Swiss mice were orally treated with three different extract concentrations (100, 300, and 500 mgkg-1). To evaluate its antigenotoxicity, the same doses were used simultaneously with a single i.p. dose of mitomycin C (MMC, 4mg.kg-1). The frequencies of micronucleated polychromatic erythrocytes (MNPCE) were evaluated 24 h and 48 h after administration except for the negative control (24 h). Genotoxicity was evaluated using the frequency of micronucleated polychromatic erythrocytes (MNPCE), whereas cytotoxicity was assessed by the polychromatic and normochromatic erythrocytes ratio (PCE/NCE). The results showed that CALE did not exhibit a significant reduction in the PCE/NCE ratio, neither a considerable increase in the frequency of MNPCE. Nonetheless, CALE reduced bone marrow toxicity (increased PCE/NCE ratio) and decreased the micronuclei frequency induced by MMC. We can conclude that CALE presented no cytotoxic and genotoxic effects, but showed antigenotoxic and anticytotoxic actions under the experimental conditions applied in this study.

Lentinula edodes (shiitake) modulates chemically induced mutagenesis by enhancing pitting

This study was undertaken to understand how Lentinula edodes modulates in vivo mutagenesis induced by alkylating agents in bone marrow and peripheral blood as described in our previous article. Male Swiss mice were pretreated for 15 consecutive days with aqueous extracts prepared from L. edodes, after which, the number of circulating blood cells, normal erythroid bone marrow cell cycling, and phagocytosis of micronucleated reticulocyte (MNRET) and activation of spleen macrophages were assessed. The results indicate that the antimutagenicity seen in bone marrow and peripheral blood is exerted by distinct compounds with different actions. The antimutagenic effect in bone marrow is exerted by compounds subject to degradation at deep-freeze storage temperature of -20°C. On the other hand, compounds responsible for antimutagenicity in peripheral blood are not subject to degradation at -20°C. The results also indicate that the antimutagenic action in peripheral blood leading to the reduction of circulating MNRET occurs in the spleen primarily through a phagocytic activity due to higher macrophage numbers and probably not due to the enhanced activation state of individual cells.

In vivo evaluation of the antimutagenic and antigenotoxic effects of β-glucan extracted from Saccharomyces cerevisiae in acute treatment with multiple doses

Ample evidence suggests that cancer is triggered by mutagenic damage and diets or supplements capable of reducing such incidences can be related to the prevention of neoplasy development or to an improvement in life quality of patients who undergo chemotherapy. This research aimed to evaluate the antimutagenic and antigenotoxic activity of β-glucan. We set up 8 experimental groups: control (Group 1), cyclophosphamide (Group 2), Groups 3–5 to assess the effect of β-glucan administration, and Groups 6–8 to evaluate the association between cyclophosphamide and β-glucan. The intraperitonial concentrations of β-glucan used were 100, 150 and 200 mg/kg. Micronucleus and comet assays showed that within the first week of treatment β-glucan presented a damage reduction rate between 100–62.04% and 94.34–59.52% for mutagenic and genotoxic damages, respectively. This activity decreased as the treatment was extended. During the sixth week of treatment antimutagenicity rates were reduced to 59.51–39.83% and antigenotoxicity was not effective. This leads to the conclusion that the efficacy of β-glucan in preventing DNA damage is limited when treatment is extended, and that its use as a chemotherapeutic adjuvant need to be better clarified.

Cytotoxicity, cytocompatibility, cell-labeling efficiency, and in vitro cellular magnetic resonance imaging of gadolinium-catalyzed single-walled carbon nanotubes

Cell tracking by magnetic resonance imaging (MRI) is an emerging technique that typically requires the use of MRI contrast agents (CAs). A MRI CA for cellular imaging should label cells efficiently at potentially safe concentrations, have high relaxivity, and not affect the cellular machinery. In this article, we report the cytotoxicity, cytocompatibility, and cell labeling efficiency in NIH/3T3 fibroblasts of novel, single-walled carbon nanotubes synthesized using gadolinium nanoparticles as catalysts (Gd-SWCNTs). Cells incubated with the Gd-SWCNT showed a dose- (50-100 µg/mL nanotube concentration) and time- (12-48 h) dependent decrease in viability. 30% cell death was observed for cells incubated with Gd-SWCNTs at the maximum dose of 100 µg/mL for 48 h. Cells incubated with the Gd-SWCNTs at concentrations between 1-10 μg/mL for 48 h showed no change in viability or proliferation compared to untreated controls. Additionally, at these potentially safe concentrations, up to 48 h, the cells showed no phosphatidyl serine externalization (pre-apoptotic condition), caspase-3 activity (point of no return for apoptosis), genetic damage, or changes in their division cycle. Localization of Gd-SWCNTs within the cells was confirmed by transmission electron microscopy (TEM) and Raman microscopy, and these results show 100% cell labeling efficiency. Elemental analysis also indicates significant uptake of Gd-SWCNTs by the cells (10(8) -10(9) Gd(3+) ions per cell). Finally, T1 -weighted MRI at 3 T of Gd-SWCNT-labelled cells show up to a four-fold increase in MR signal intensities as compared to untreated cells. These results indicate that Gd-SWCNTs label cells efficiently at potentially safe concentrations, and enhance MRI contrast without any structural damage to the cells.

Effects of β-glucan polysaccharide revealed by the dominant lethal assay and micronucleus assays, and reproductive performance of male mice exposed to cyclophosphamide

β-glucan is a well-known polysaccharide for its chemopreventive effect. This study aimed to evaluate the chemopreventive ability of β-glucan in somatic and germ cells through the dominant lethal and micronucleus assays, and its influence on the reproductive performance of male mice exposed to cyclophosphamide. The results indicate that β-glucan is capable of preventing changes in DNA in both germ cells and somatic ones. Changes in germ cells were evaluated by the dominant lethal assay and showed damage reduction percentages of 46.46% and 43.79% for the doses of 100 and 150 mg/kg. For the somatic changes, evaluated by micronucleus assay in peripheral blood cells in the first week of treatment, damage reduction percentages from 80.63–116.32% were found. In the fifth and sixth weeks, the percentage ranged from 10.20–52.54% and −0.95–62.35%, respectively. Besides the chemopreventive efficiency it appears that the β-glucan, when combined with cyclophosphamide, is able to improve the reproductive performance of males verified by the significant reduction in rates of post-implantation losses and reabsorption in the mating of nulliparous females with males treated with cyclophosphamide.

Evaluation of the mutagenicity and antimutagenicity of soy phytoestrogens using micronucleus and comet assays of the peripheral blood of mice

Studies show that soy imparts many favorable properties in the human body, including the prevention of chronic diseases such as osteoporosis, heart disease, cancer, and diabetes. Soy is rich in isoflavones, and it is a candidate for the chemoprevention of diseases owing to its low toxicity. In this study, a soy phytoestrogen (with high levels of the isoflavones genistin and daidzein) was tested in mice to investigate its mutagenicity and genotoxicity using micronucleus and comet assays of mouse peripheral blood. Phytoestrogen (0.083, 0.83 and 8.3 mg/kg body weight) was evaluated with and without the chemotherapeutic agent cyclophosphamide. For the micronucleus assay, blood was collected before treatment and after 24 and 48 h. For the comet assay, blood was collected only after 24 h. Phytoestrogen was not mutagenic and reduced cyclophosphamide-induced DNA damage. The results from the comet assay revealed a reduction of DNA damage; however, phytoestrogen did induce genotoxic damage during the 24-h treatment. This genotoxic damage could have been repaired and was therefore not identified in the micronucleus assay, which detects mutations. The results suggested that the reduction of DNA damage observed in associated treatments could also reduce the side effects of chemotherapy. Moreover, they suggested that phytoestrogen might be a candidate of interest for the chemoprevention of cancer because it protects against DNA damage.

Exposure to lambda-cyhalothrin, a synthetic pyrethroid, increases reactive oxygen species production and induces genotoxicity in rat peripheral blood

Lambda-cyhalothrin (LTC) is a synthetic pyrethroid with a broad spectrum of insecticidal and acaricidal activities used to control a wide range of insect pests in a variety of applications. However, there is little known about its adverse effects, in particular those related to its genotoxicity in humans. To elucidate the genotoxicity mechanisms of LTC, the micronuclei (MN) frequencies, the levels of reactive oxygen species (ROS), erythrocyte osmotic fragility, nitrite (NO) formation, protein carbonyl (PCO) levels and malondialdehyde (MDA) production were evaluated for a period of 7, 14 and 21 days. Our results show that exposure rat to LTC (1/10DL50 = 6.23 mg/kg) for a period of 7, 14 and 21 days induced a noticeable genotoxic effect in rat peripheral blood evidenced by a significant increase in the frequency of MN only at day 21 of treatment. Significant differences between the two groups were observed in erythrocyte osmotic fragility. Further, a significant (p < 0.01) increase in ROS contents, NO formation, PCO levels and lipid peroxidation in erythrocytes were observed at different times of treatments, suggesting the implication of oxidative stress in its toxicity. These results confirm the genotoxic and the pro-oxidant effects of LTC in rat peripheral blood.

In vivo micronucleus assay in mouse bone marrow and peripheral blood

The rodent micronucleus assay has been most widely and frequently used as a representative in vivo assay system to assess mutagenicity of chemicals, regardless of endpoint of mutagenicity. The micronucleus has been developed to assess induction of structural and numerical chromosomal aberrations of target chemical. In this chapter, we describe the standard protocols of the assay using mouse bone marrow and peripheral blood. These methods are basically applicable to other rodents. The methodology of the micronucleus assay is rapidly developing, especially automatic analysis by flow cytometry (see also Chapter 11 ). Also we have to pay attention to the animal welfare, for example integration into repeat dose toxicity assay, combination of the micronucleus assay and Comet assay, and also omission of concurrent positive control group. Therefore, modification of the standard protocol is necessary for the actual assay on a case-by-case basis.

Genotoxic and mutagenic effects of diflubenzuron, an insect growth regulator, on mice

This study assessed the genotoxic and mutagenic potential of diflubenzuron (DFB) insecticide in mice. Mice were divided into five groups: group I: negative control; group II: positive control; group III: 0.3 mg/kg of DFB; group IV: 1 mg/kg of DFB; group V: 3 mg/kg DFB. Peripheral blood was collected for the comet assay and the micronucleus (MN) test. DFB increased incidence of comet formation at all doses tested. A rise in the frequency of MN in mouse peripheral blood was observed 24, 48, and 72 h postexposure at all doses tested. Data demonstrate that DFB exerts genotoxic and mutagenic effects in a dose-dependent manner.

A novel microplate-based assay for screening radioprotectors and its validation based on DNA and membrane system

Ionizing radiation leads to damage at various cellular and sub-cellular levels and can be prevented by radioprotectors. There are many in vitro and in vivo but rather expensive assays for screening of radioprotectors from natural and synthetic sources. We have developed a cell free radioprotector screening assay which involves bleaching of crocin pigment, isolated from saffron by radiolytic products of water. Any molecules/compounds which can inhibit the bleaching of the crocin will act as a radioprotector. The developed assay was further validated by the existing in vitro assays. Different radioprotectors have different level for inhibition of bleaching of crocin. The trends of radioprotection offered by crocin bleaching assay, plasmid relaxation and lipid peroxidation are TMG>FA>VA>Amifos>Trox, TMG>VA>FA>Amifos>Trox, and TMG>FA>Trox>VA>Amifos, respectively. We are getting different trends for different assays. This is because different drugs have different mechanisms of radioprotection in different assay systems. In conclusion, the crocin bleaching assay developed here is a simple, fast and economical screening assay and it will have great value in radioprotection programme for screening many potential compounds for radioprotection.

Prevention of γ-radiation induced cellular genotoxicity by tempol: protection of hematopoietic system

Tempol (TPL) under in vitro conditions reduced the extent of gamma radiation induced membrane lipid peroxidation and disappearance of covalently closed circular form of plasmid pBR322. TPL protected cellular DNA from radiation-induced damage in various tissues under ex vivo and in vivo conditions as evidenced by comet assay. TPL also prevented radiation induced micronuclei formation (in peripheral blood leucocytes) and chromosomal aberrations (in bone marrow cells) in whole body irradiated mice. TPL enhanced the rate of repair of cellular DNA (blood leucocytes and bone marrow cells) damage when administered immediately after radiation exposure as revealed from the increased Cellular DNA Repair Index (CRI). The studies thus provided compelling evidence to reveal the effectiveness of TPL to protect hematopoietic system from radiation injury.

Design, synthesis, and pharmacological evaluation of novel hybrid compounds to treat sickle cell disease symptoms. part II: furoxan derivatives

Phthalimide derivatives containing furoxanyl subunits as nitric oxide (NO)-donors (3a-g) were designed, synthesized, and evaluated in vitro and in vivo for their potential uses in the oral treatment of sickle cell disease symptoms. All compounds (3a-g) demonstrated NO-donor properties at different levels. Moreover, compounds 3b and 3c demonstrated analgesic activity. Compound 3b was determined to be a promising drug candidate for the aforementioned uses, and it was further evaluated in K562 culture cells to determine its ability to increase levels of γ-globin expression. After 96 h at 5 μM, compound 3b was able to induce γ-globin expression by nearly three times. Mutagenic studies using micronucleus tests in peripheral blood cells of mice demonstrated that compound 3b reduces the mutagenic profile as compared with hydroxyurea. Compound 3b has emerged as a new leading drug candidate with multiple beneficial effects for the treatment of sickle cell disease symptoms and provides an alternative to hydroxyurea treatment.

Genotoxicity assessment of Copaiba oil and its fractions in Swiss mice

Copaiba oil-resin, extracted from the trunk of Copaifera, and traditionally used in folk medicine in the treatment of various disorders, has been shown to be an effective antiinflamatory, antitumor, antitetanus, antiseptic and anti-blenorrhagea agent. As, there are few studies evaluating its genotoxicity, this aspect of the commercial oil-resin, and its volatile and resinous fractions, were evaluated in mice by comet assay and micronucleus (MN) test. A single dose of oil resin, volatile or resin fractions (500; 1,000 or 2,000 mg/kg b.w.) was administered by gavage. The chemical compositions of Copaiba oil resin and its fractions was analyzed by gas chromatography. According to comet assaying, treatment with either one did not increase DNA damage, and as to MN testing, there was no alteration in the incidence of micronucleated polychromatic erythrocytes. Chromatographic analysis of the oil-resin itself revealed sesquiterpenes, diterpenic carboxylic acid methyl esters and high levels of β-caryophyllene. Thus, it can be assumed that the oil resin and volatile and resinous fractions from the commercial product are not genotoxic or mutagenic.

Antigenotoxic effects of piquiá (Caryocar villosum) in multiple rat organs

This study investigated the in vivo genotoxicity of piquiá pulp (Caryocar villosum) and its potential antigenotoxicity on doxorubicin (DXR)-induced DNA damage by comet assay and micronucleus test. In addition, the phytochemicals present in piquiá pulp were determined. Piquiá fruit pulp (75, 150 or 300 mg/kg b.w.) was administered by gavage to Wistar rats for 14 days, and the animals received an injection of saline or DXR (15 mg/kg b.w., i.p.) 24 h before they were euthanized. The phytochemical analysis revealed the presence of carotenoids; phenolic compounds, including flavonoids; tannins and α-tocopherol in piquiá pulp. No statistically significant differences were observed in the evaluated parameters, demonstrating the absence of cytotoxic and genotoxic effects of piquiá pulp at all tested doses. In liver, kidney, cardiac and bone marrow cells, piquiá significantly reduced the DNA damage induced by DXR. Our results showed that the lowest piquiá dose caused the largest decrease in DNA damage and the highest dose caused the smallest decrease, demonstrating an inverse dose-response of piquiá pulp. Furthermore, we observed a difference in the potential antigenotoxic effects in several tissues. In conclusion, our results demonstrated that piquiá pulp was not genotoxic and inhibited the genotoxicity induced by DXR, but some of the protective effects that were observed depended on the doses and experimental conditions. Therefore, further investigations are needed to clarify how piquiá pulp positively affects human health.

Differences in micronucleus induction in peripheral blood reticulocytes of mice exposed to N-ethyl-N-nitrosourea at light and dark dosing times

Mammals, including human beings, have a circadian clock system to regulate behavioral and physiological processes. In this study, we investigated the effect of dosing time on micronucleus induction in the bone marrow by evaluating the frequencies of micronucleated peripheral reticulocytes (MNRETs) in mice exposed to N-ethyl-N-nitrosourea (ENU) to assess any difference in genotoxic sensitivity to chemicals between light and dark periods (inactive phase for rodents and active phase for rodents). Male C3H/He mice were treated intraperitoneally with ENU (12.5 or 25 mg/kg body weight) at zeitgeber time (ZT) 3 in the light period or ZT15 in the dark period, and then the time courses of the frequencies of the MNRETs were determined. The frequencies of the MNRETs induced by ENU increased time-dependently and peaked at 48 hr after treatment for ZT3 and ZT15, and were obviously higher in the ZT15 treatment group than the ZT3 treatment group. The MNRETs were measured at 48 hr after treatment with ENU (25 mg/kg body weight) at various dosing times (ZT0, 3, 6, 12, 15 and 18). The frequencies of the MNRETs in mice treated at ZT0, 15 and 18 were significantly higher than those in mice treated at ZT3, 6 and 12. These results suggest that genotoxic sensitivity to chemicals in mouse bone marrow is different between light and dark periods maybe due to different biological responses (detoxification, cell cycle, DNA repair, etc.) related to circadian rhythms.

Metal nanoparticle-induced micronuclei and oxidative DNA damage in mice

Several mechanisms regarding the adverse health effects of nanomaterials have been proposed. Among them, oxidative stress is considered to be one of the most important. Many in vitro studies have shown that nanoparticles generate reactive oxygen species, deplete endogenous antioxidants, alter mitochondrial function and produce oxidative damage in DNA. 8-Hydroxy-2'-deoxyguanosine is a major type of oxidative DNA damage, and is often analyzed as a marker of oxidative stress in human and animal studies. In this study, we focused on the in vivo toxicity of metal oxide and silver nanoparticles. In particular, we analyzed the induction of micronucleated reticulocyte formation and oxidative stress in mice treated with nanoparticles (CuO, Fe₃O₄, Fe₂O₃, TiO₂, Ag). For the micronucleus assay, peripheral blood was collected from the tail at 0, 24, 48 and 72 h after an i.p. injection of nanoparticles. Following the administration of nanoparticles by i.p. injection to mice, the urinary 8-hydroxy-2'-deoxyguanosine levels were analyzed by the HPLC-ECD method, to monitor the oxidative stress. The levels of 8-hydroxy-2'-deoxyguanosine in liver DNA were also measured. The results showed increases in the reticulocyte micronuclei formation in all nanoparticle-treated groups and in the urinary 8-hydroxy-2'-deoxyguanosine levels. The 8-hydroxy-2'-deoxyguanosine levels in the liver DNA of the CuO-treated group increased in a dose-dependent manner. In conclusion, the metal nanoparticles caused genotoxicity, and oxidative stress may be responsible for the toxicity of these metal nanoparticles.

Mutagenicity and safety evaluation of the water extract of Camellia oleifera Abel

The purpose of this study was to evaluate the mutagenicity and safety of water extract of the fruit hull of Camellia oleifera Abel (WECO), which was prepared using hot-reflux method. The oral maximum tolerated dose (MTD) of WECO was above 20 g/kg body weight both in rats and in mice, which can be regarded as virtually nontoxic. No mutagenicity was found in Ames test, mouse bone marrow cell micronucleus test and mouse sperm abnormality test. In the subacute study, the SD rats were administered orally at 0.5, 1, or 2 g/kg/BW for 30 d. There were no treatment-related toxic effects from WECO. No significant differences were found in parameters of body weight, hematology value, clinical chemistry value, and organ/body weight ratio. The level of no observed adverse effect level (NOAEL) for WECO was 2 g/kg/BW for subacute toxicity study.

PRACTICAL APPLICATION

  With the gradual increase in tea oil production, it was in urgent need of dealing with Camellia fruit hull, which was always discarded because of low economic benefits. Camellia fruit hull has been shown to have significant antioxidant effects including DPPH radical-scavenging ability and ferric-reducing antioxidant power (Zhang and others 2010). Toxicological evaluation of WECO provided a safety assurance of WECO for developing dietary supplements and functional foods.

Identification of differentially expressed genes in the livers of chronically i-As-treated hamsters

Inorganic arsenic (i-As) is a human carcinogen causing skin, lung, urinary bladder, liver and kidney tumors. Chronic exposure to this naturally occurring contaminant, mainly via drinking water, is a significant worldwide environmental health concern. To explore the molecular mechanisms of arsenic hepatic injury, a differential display polymerase chain reaction (DD-PCR) screening was undertaken to identify genes with distinct expression patterns between the liver of low i-As-exposed and control animals. Golden Syrian hamsters (5-6 weeks of age) received drinking water containing 15 mg i-As/L as sodium arsenite, or unaltered water for 18 weeks. The in vivo MN test was carried out, and the frequency of micronucleated reticulocytes (MN-RETs) was scored as a measure of exposure and As-related genotoxic/carcinogenic risk. A total of 68 differentially expressed bands were identified in our initial screen, 41 of which could be assigned to specific genes. Differential level of expression of a selected number of genes was verified using real-time RT-PCR with gene-specific primers. Arsenic-altered gene expression included genes related to stress response, cellular metabolism, cell cycle regulation, telomere maintenance, cell-cell communication and signal transduction. Significant differences of MN-RET were found between treated (8.70 ± 0.02 MN/1000RETs) and control (2.5 ± 0.70 MN/1000RETs) groups (P<0.001), demonstrating both the exposure and the i-As genotoxic/carcinogenic risk. Overall, this paper reveals some possible networks involved in hepatic arsenic-related genotoxicity, carcinogenesis and diabetogenesis. Additional studies to explore further the potential implications of each candidate gene are of especial interest. The present work opens the door to new prospects for the study of i-As mechanisms taking place in the liver under chronic settings.

An evaluation, using the comet assay and the micronucleus test, of the antigenotoxic effects of chlorophyll b in mice

We investigated the effects of the dietary pigment chlorophyll b (CLb) on cisplatin (cDDP)-induced oxidative stress and DNA damage, using the comet assay in mouse peripheral blood cells and the micronucleus (MN) test in bone marrow and peripheral blood cells. We also tested for thiobarbituric acid reactive substances (TBARS) and reduced glutathione (GSH) in liver and kidney tissues, as well as catalase (CAT) activity and GSH in total blood. CLb (0.2 and 0.5mg/kg b.w.) was administrated by gavage every day for 13 days. On the 14th day of the experiment, 6 mg/kg cDDP or saline was delivered intraperitoneally. Treatment with cDDP led to a significant decrease in DNA migration and an increase in MN frequency in both cell types, bone marrow and peripheral blood cells. In the kidneys of mice treated with cDDP, TBARS levels were increased, whereas GSH levels were depleted in kidney and liver. In mice that were pre-treated with CLb and then treated with cDDP, TBARS levels maintained normal concentrations and GSH did not differ from cDDP group. The improvement of oxidative stress biomarkers after CLb pre-treatment was associated with a decrease in DNA damage, mainly for the highest dose evaluated. Furthermore, CLb also slightly reduced the frequency of chromosomal breakage and micronucleus formation in mouse bone marrow and peripheral blood cells. These results show that pre-treatment with CLb attenuates cDDP-induced oxidative stress, chromosome instability, and lipid peroxidation.

Evaluation of extracts from Coccoloba mollis using the Salmonella/microsome system and in vivo tests

The common everyday use of medicinal plants is an ancient, and still very widespread practice, whereby the need for studies on their possible toxicity and mutagenic properties. The species Coccoloba mollis has been much used in phytotherapy, mainly in cases involving loss of memory and stress. In order to investigate its genotoxic and mutagenic potential, ethanolic extracts from the leaves and roots underwent Salmonella/microsome assaying (TA98 and TA100 strains, with and without exogenous metabolism – S9), besides comet and micronucleus tests in vivo.There was no significant increase in the number of revertants/plate of Salmonella strains in any of the analyzed root-extract concentrations, although the extract itself was extremely toxic to the Salmonella TA98 strain in the tests carried out with S9 (doses varying from 0.005 to 0.5 μg/plate). On the other hand, the leaf-extract induced mutations in the TA98 strain in the absence of S9 in the highest concentration evaluated, although at very low mutagenic potency (0.004 rev/ μg). Furthermore, there was no statistically significant increase in the number of comets and micronuclei, in treatments involving Swiss mice. It was obvious that extracts of Coccoloba mollis, under the described experimental conditions, are not mutagenic.