Genotoxic effects of potassium bromate on human peripheral lymphocytes in vitro

Toxicity assessment of potassium bromate and the remedial role of grape seed extract

In this study, the multiple toxic effects of potassium bromate were investigated in Allium cepa L., an indicator test material. In addition, the toxicity-reducing effects of grape seed extract (GSE) were tested. The toxicity was investigated by some physiological (germination percentage, root length, weight gain, relative injury rate), cytogenetic [mitotic index (MI), micronucleus (MN), and chromosomal abnormalities (CAs)], biochemical [malondialdehyde (MDA), superoxide dismutase (SOD), catalase (CAT), glutathione (GSH) levels] and anatomical parameters. A. cepa bulbs were divided into 6 groups as control and five treatment groups (Group II: 465 mg/L GSE, Group III: 930 mg/L GSE, Group IV: 100 mg/L potassium bromate, Group V: 100 mg/L potassium bromate + 465 mg/L GSE, Group VI: 100 mg /L potassium bromate + 930 mg/L GSE). The bulbs were germinated for 72 h and at the end of the period the bulbs were subjected to routine preparations and made ready for analysis and measurements. As a result, potassium bromate exposure caused statistically significant (p < 0.05) decreases in all physiological parameter values. Potassium bromate application decreased MI by 41.6%, and increased the MN and CAs frequencies. CAs such as fragment, sticky chromosome, and vagrant chromosome, unequal distribution of chromatin, reverse polarization, nuclear bud and disordered mitosis were induced in root meristem cells. The mechanism of potassium bromate genotoxicity has been associated with DNA-potassium bromate interaction supported by spectral shift. Potassium bromate caused a decrease in GSH levels and an increase in MDA, SOD and CAT levels, thereby disrupting the antioxidant/oxidant balance in root tip cells. GSE administration in two different doses together with potassium bromate reduced the toxic effects and caused improvements in all parameters examined. The most significant reduction in toxicity was in group VI, which received 930 mg/L GSE, and there was an improvement about 18% in MI levels and an improvement about 44% in GSH levels in this group. While GSE application increased physiological parameters and GSH levels, it decreased MDA, SOD, CAT levels, MN and CAs frequencies. As a result, it has been determined that potassium bromate causes multi-directional toxicity at high doses and A. cepa is a very reliable indicator in determining this toxicity. In addition, GSE extract has been found to have a strong role in reducing the toxicity induced by potassium bromate.

New aspects in deriving health-based guidance values for bromate in swimming pool water

Bromate, classified as a EU CLP 1B carcinogen, is a typical by-product of the disinfection of drinking and swimming pool water. The aim of this study was (a) to provide data on the occurrence of bromate in pool water, (b) to re-evaluate the carcinogenic MOA of bromate in the light of existing data, (c) to assess the possible exposure to bromate via swimming pool water and (d) to inform the derivation of cancer risk-related bromate concentrations in swimming pool water. Measurements from monitoring analysis of 229 samples showed bromate concentrations in seawater pools up to 34 mg/L. A comprehensive non-systematic literature search was done and the quality of the studies on genotoxicity and carcinogenicity was assessed by Klimisch criteria (Klimisch et al., Regul Toxicol Pharmacol 25:1-5, 1997) and SciRAP tool (Beronius et al., J Appl Toxicol, 38:1460-1470, 2018) respectively. Benchmark dose (BMD) modeling was performed using the modeling average mode in BMDS 3.1 and PROAST 66.40, 67 and 69 (human cancer BMDL10; EFSA 2017). For exposure assessment, data from a wide range of sources were evaluated for their reliability. Different target groups (infants/toddlers, children and adults) and exposure scenarios (recreational, sport-active swimmers, top athletes) were considered for oral, inhalation and dermal exposure. Exposure was calculated according to the frequency of swimming events and duration in water. For illustration, cancer risk-related bromate concentrations in pool water were calculated for different target groups, taking into account their exposure using the hBMDL10 and a cancer risk of 1 in 100,000. Convincing evidence was obtained from a multitude of studies that bromate induces oxidative DNA damage and acts as a clastogen in vitro and in vivo. Since statistical modeling of the available genotoxicity data is compatible with both linear as well as non-linear dose-response relationships, bromate should be conservatively considered to be a non-threshold carcinogen. BMD modeling with model averaging for renal cancer studies (Kurokawa et al., J Natl. Cancer Inst, 1983 and 1986a; DeAngelo et al., Toxicol Pathol 26:587-594, 1998) resulted in a median hBMDL10 of 0.65 mg bromate/kg body weight (bw) per day. Evaluation of different age and activity groups revealed that top athletes had the highest exposure, followed by sport-active children, sport-active adults, infants and toddlers, children and adults. The predominant route of exposure was oral (73-98%) by swallowing water, followed by the dermal route (2-27%), while the inhalation route was insignificant (< 0.5%). Accepting the same risk level for all population groups resulted in different guidance values due to the large variation in exposure. For example, for an additional risk of 1 in 100,000, the bromate concentrations would range between 0.011 for top athletes, 0.015 for sport-active children and 2.1 mg/L for adults. In conclusion, the present study shows that health risks due to bromate exposure by swimming pool water cannot be excluded and that large differences in risk exist depending on the individual swimming habits and water concentrations.

The effect of redox agents on conformation and structure characterization of gluten protein: An extensive review

Gluten protein as one of the plant resources is affected by redox agent. Chemical modifications by redox agent have myriad advantages mainly short reaction times, no requirement for specialized equipment, low cost, and highly clear modification impacts. The gluten network properties could be influenced through redox agents (oxidative and reducing agents) which are able to alter the strength of dough via different mechanisms for various purposes. The present review examined the impact of different redox compounds on gluten and its subunits based on their effects on their bonds and conformations and thus with their impacts on the physico-chemical, morphological, and rheological properties of gluten and their subunits. This allows for the use of gluten for different of purposes in the food and nonfood industry.

Potassium bromate: Effects on bread components, health, environment and method of analysis: A review

Potassium bromate, is an oxidizing agent and one of the best and cheapest dough improvers in the baking industry. Due to its positive effects it plays a major role in the bread-making industry. Potassium bromate has significant effect on food biomolecules, such as starch and protein, as it affects the extent of gelatinization, viscosity, swelling characteristics as well as gluten proteins; it removes the sulfhydryl group and leads to the formation of disulfide linkages and thus improves the bread properties. However, there are many reports elucidating its negative impact on human health. It is deemed as a potential human carcinogen by IARC and classified under class 2B. Due to this, countries across world have either partially or completely banned it. Numerous techniques have evolved to determine the concentration of potassium bromate in bread. This review explains in detail, the effects of potassium bromate on biomolecules, human health, environment and various methods of analysis.

Vitamin E protects against cisplatin-induced genotoxicity in human lymphocytes

Cisplatin is an anticancer drug that is widely used in treatments of human malignancies such as ovaries,' testes,' and solid tumors of the head and neck. However, the use of cisplatin in the treatments can be associated with DNA damage and high risk to the development of secondary malignancies. Vitamin E is a strong lipophilic antioxidant that has the ability to protect normal cells from chromosomal damage and promote the repair of the damaged DNA. In the current study, the possible protective effect of vitamin E on DNA damage induced by cisplatin was investigated. For that, chromosomal aberrations (CAs) frequency and the number of sister chromatid exchanges (SCEs) were measured in cultured human lymphocytes. Results showed that cisplatin statistically significant increases in the number of cells with CAs (P < 0.05) and in the frequency of SCEs (P < 0.05) as compared to the control group. These increases were significantly lowered by pretreatment of cells with vitamin E. Additionally, cisplatin reduced mitotic index at used concentrations (P < 0.05), which was normalized by vitamin E. Therefore, we conclude that vitamin E can prevent the genotoxicity of cisplatin on cultured human lymphocyte.

Oral administration of a potassium bromate dosage: Determination and evaluation of accumulated bromate on the liver of male mice

In this work, we developed a simple spectrophotometric strategy for BrO₃^- ions determination as a major water disinfection constituents in the mice's liver tissues by using pararosaniline (PRA). Mice were divided into seven main groups (6 doses): lowest dose KBrO₃ (G₁ 0.01 mg L^-1, G₂ 0.025 mg L^-1 and G₃ 0.1 mg L^-1), highest dose KBrO₃ (G₄ 1 mg L^-1, G₅ 10 mg·L^-1 and G₆ 30 mg L^-1) and control. All these groups maintained a dose-specific feeding for one month, just before the bromate assessment in mice's liver samples. The results revealed that groups of exposure to lower doses of drinking water did not detect the presence of BrO₃^- accumulated in the liver tissue during the study period (1-2 months). While, the BrO₃^- was detected in higher dosages for samples analyzed in first, second, third, fourth and fifth weeks (W₁, W₂, W₃, W₄, and W₅). These results confirmed that the higher BrO₃^- dosages (1, 10, and 30 mg L^-1) were fatal if introduced in drinking water and could accumulate in the liver tissues both for mice and for human. Detection the accuracy of the method for recovery of bromate ions in liver samples (N = 5) was found to be more than 95%. Relative standard deviations (RSDs) were found to be less than 2.0% confirming the reproducibility of the assay technique.

Ozonation of whole wheat flour and wet milling effluent: Degradation of deoxynivalenol (DON) and rheological properties

The objective of this study was to evaluate the reduction on the levels of the mycotoxin deoxynivalenol (DON) in whole wheat flour (WWF) with different moisture levels, on the wet milling effluent through ozone (O₃) processing, as well as the impact of ozonation on the rheological properties of flour. The results have shown that the reduction of DON was improved with increasing moisture and exposure time of WWF and wet milling effluent to ozone. The maximum reduction was about 80%, proving that ozonation is an effective and promising technology in reducing mycotoxins in different products. However, the process altered the rheological profile of WWF. Therefore, further studies are needed to better understand the process.

Deleterious effects of potassium bromate administration on renal and hepatic tissues of Swiss mice

Potassium bromate (KBrO₃) is widely used as a food additive and is a major water disinfection by-product. The present study reports the side effects of KBrO₃ administration in Swiss mice. Animals were randomly divided into three groups: control, low dose KBrO₃ (100 mg/kg/day) and high dose KBrO₃ (200 mg/kg/day) groups. Administration of KBrO₃ led to decreased white blood corpuscles (WBCs), red blood corpuscles (RBCs) and platelets count in the animals of both the high and the low dose groups. Altered lipid profile represented as low density lipoprotein (LDL), high density lipoprotein (HDL) and cholesterol levels were observed in plasma samples of both KBrO₃ treated groups of mice. Also, an increased plasma level of LDH was detected in both KBrO₃ treated groups. Histological investigations showed impaired renal and hepatic histology that was concomitant with increased plasma Creatinine level in both of KBrO₃-treated groups. Nevertheless, decreased glutathione (GSH) level in both renal and hepatic tissue of mice after KBrO₃ intake was detected. These results show that KBrO₃ has serious damaging effects and therefore, its use should be avoided.

The role of natural indigo dye in alleviation of genotoxicity of sodium dithionite as a reducing agent

Indigo blue is a natural dye used for thousands of years by civilizations to dye fabric blue and it is naturally obtained from Isatis tinctoria. I. tinctoria is not only used for extraction of indigo blue color but also used medicinally in Traditional Chinese Medicine because of its active compounds. Sodium dithionite (Na₂S₂O₄) is used in dye bath for indigo blue extraction, but this reducing agent and its derivatives are major pollutants of textile industry and subsequently have hazardous influences on public health. Herein, the present study was designed to obtain the high yield of natural indigo dye but with low possible toxic effect. In this context, genotoxic effects of particular combinations of natural dye solutions obtained from Isatis tinctoria subsp. tomentolla with Na₂S₂O₄ as reducing agent were investigated. Dye solutions were obtained using two different pH levels (pH 9 and 11) and three different concentrations of Na₂S₂O₄ (2.5, 5 and 10 mg/ml). In addition to the dye solutions and reducing agent, aqueous extracts of I. tinctoria were assessed for their genotoxicity on human lymphocytes. For in vitro testing of genotoxicity, chromosomal aberrations (CAs), sister chromatid exchanges (SCEs) and mitotic indexes (MI) assays were used. Accordingly, Na₂S₂O₄ caused significant increases in CA and SCE as well decrease in MI but the genotoxic effects of sodium dithionite were reduced with natural indigo dye. As a result, aqueous extracts of Isatis leaves removed the toxic effects of sodium dithionite and showed anti-genotoxic effect. For the optimal and desired quality but with less toxic effects of natural dye, 2.5 mg/ml (for wool yarn) and 5 mg/ml (for cotton yarn) of Na₂S₂O₄ doses were found to be the best doses for reduction in the dye bath at Ph 9.

Assessment of genotoxicity of vincristine, vinblastine and vinorelbine in human cultured lymphocytes: a comparative study

Vincristine (VCR), vinblastine (VBL) and vinorelbine (VRL) are anticancer agents from the Vinca alkaloid family that have the potential to induce genotoxic effect. The aim of the present study was to compare the genotoxic effect of VCR, VBL and VRL. Levels of 8-hydroxy-2-deoxy guanosine (8-OHdG) and sister chromatid exchanges (SCEs) were measured in cultured human blood lymphocytes treated with VCR, VBL and VRL at concentrations of 0.01 and 0.1 μg/mL. Results showed that VCR, VBL and VRL significantly increased the 8-OHdG levels (p <0.05), whereas it did not cause a significant increase in the frequencies of SCEs in human blood lymphocytes as compared to controls. On the other hand, all three agents significantly increased cells mitotic index (p <0.05). At both tested concentrations, the magnitude of the increase in 8-OHdG was VBL>VCR>VRL. In conclusion, VCR, VBL and VRL induce DNA damage as indicated by the increase in the 8-OHdG biomarker but with different magnitude.

Effect of Potassium Bromate on the Liver of Adult Male Albino Rat and A Possible Protective Role of Vitamin C: Histological, Immunohistochemical, and Biochemical Study

Potassium bromate (KBrO3 ) is a food additive which is used primarily as a maturing agent for flour. It is proved as a toxic agent with significant reduction in the activities of antioxidant capacity. The therapeutic efficacy of vitamin C as antioxidant may provide a possible solution to KBrO3 mediated oxidative damage. Twenty four adult male albino rats were used to evaluate the protective role of vitamin C against KBrO3 induced hepatotoxicity and divided into four groups; Group 1 (control), Group 2: received 30 mg/Kg/day vitamin C orally for 4 weeks, Group 3: received 20 mg/Kg/dose KBrO3 orally twice weekly for 4 weeks and Group 4: received both KBrO3 and vitamin C. Liver specimens were processed for histological study by light and electron microscopes and stained immunohistochemically to detect glial fibriller acidic protein (GFAP). Serum levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) were estimated as well as the levels of malondialdehyde (MDA), glutathione (GSH) and superoxide dismutase (SOD) activities in all dissected tissues were determined. KBrO3 induced histological alterations in the form of degeneration, cellular infiltration and significant increase in collagen deposition in portal tracts with a significant increase in immunoexpression of GFAP. Significant rise in serum levels of AST, ALT, and MDA in liver tissues were recorded. However, levels of GSH and SOD were significantly decreased. Most of these changes were improved by vitamin C treatment. In conclusion, vitamin C ameliorates the histological and biochemical alterations of the liver induced by KBrO3 . Anat Rec, 299:1256-1269, 2016. © 2016 Wiley Periodicals, Inc.

Direct spectral analysis and determination of high content of carcinogenic bromine in bread using UV pulsed laser induced breakdown spectroscopy

Laser induced breakdown spectroscopy (LIBS) was applied for the detection of carcinogenic elements like bromine in four representative brands of loaf bread samples and the measured bromine concentrations were 352, 157, 451, and 311 ppm, using Br I (827.2 nm) atomic transition line as the finger print atomic transition. Our LIBS system is equipped with a pulsed laser of wavelength 266 nm with energy 25 mJ pulse(-1), 8 ns pulse duration, 20 Hz repetition rate, and a gated ICCD camera. The LIBS system was calibrated with the standards of known concentrations in the sample (bread) matrix and such plot is linear in 20-500 ppm range. The capability of our system in terms of limit of detection and relative accuracy with respect to the standard inductively coupled plasma mass spectrometry (ICPMS) technique was evaluated and these values were 5.09 ppm and 0.01-0.05, respectively, which ensures the applicability of our system for Br trace level detection, and LIBS results are in excellent agreement with that of ICPMS results.

Kinetics and Mechanism of Oxidation of d-Penicillamine in Acidified Bromate and Aqueous Bromine

The oxidation of the biologically active compound d-penicillamine (Depen) by acidic bromate has been studied. The stoichiometry of the reaction is strictly 1 : 1, in which Depen is oxidized only as far as the sulfonic acid with no cleavage of the C–S bond to yield sulfate. Electrospray ionization spectroscopy shows that Depen is oxidized through addition of oxygen atoms on the sulfur centre to successively yield sulfenic and sulfinic acids before the product sulfonic acid. In conditions of excess Depen over the oxidant, sulfenic acid was not observed. Instead, nearly quantitative formation of the dimer was obtained. The dimer, which is the d-penicillamine disulfide species, was formed from a reaction of the putative highly electrophilic sulfenic acid with unreacted Depen in a condensation-type reaction and not through a radical-mediated pathway. Further oxidation of the dimer is slow because it is the most stable intermediate in the oxidation of Depen. In excess oxidant conditions, negligible dimer formation is observed. The reaction of bromine with Depen gives a stoichiometry of 3 : 1 with the same sulfonic acid product. This reaction is so fast that it is essentially diffusion controlled. Our stopped-flow instrument could not capture the oxidation by the first 2 moles of bromine, only the section of the reaction in which the sulfinic acid is oxidized to sulfonic acid.

Tempol prevents genotoxicity induced by vorinostat: role of oxidative DNA damage

Vorinostat is a member of histone deacetylase inhibitors, which represents a new class of anticancer agents for the treatment of solid and hematological malignancies. Studies have shown that these drugs induce DNA damage in blood lymphocytes, which is proposed to be due to the generation of oxidative lesions. The increase in DNA damage is sometimes associated with risk of developing secondary cancer. Thus, finding a treatment that limits DNA damage caused by anticancer drugs would be beneficial. Tempol is a potent antioxidant that was shown to prevent DNA damage induced by radiation. In this study, we aimed to investigate the harmful effects of vorinostat on DNA damage, and the possible protective effects of tempol against this damage. For that, the spontaneous frequency of sister chromatid exchanges (SCEs), chromosomal aberrations (CAs), and 8-hydroxy-2-deoxy guanosine (8-OHdG) levels were measured in cultured human lymphocytes treated with vorinostat and/or tempol. The results showed that vorinostat significantly increases the frequency of SCEs, CAs and 8-OHdG levels in human lymphocytes as compared to control. These increases were normalized by the treatment of cells with tempol. In conclusion, vorinostat is genotoxic to lymphocytes, and this toxicity is reduced by tempol. Such results could set the stage for future studies investigating the possible usefulness of antioxidants co-treatment in preventing the genotoxicity of vorinostat when used as anticancer in human.

Genotoxicity of structurally related copper and zinc containing Schiff base complexes

The utilization of Schiff bases in the industrial and pharmaceutical fields has led to an increase in their syntheses and evaluation of their biological activities. In this study, we described the synthesis and genotoxicity of two Schiff bases that share common platform in their construction, namely, naphthalene, and are complexed to either Cu(II) or Zn(II). The genotoxicity of these complexes was evaluated in cultured lymphocytes using sister chromatid exchanges (SCEs) and chromosomal aberrations (CAs), and in rats using the urine 8-OH-2-deoxyguanosine (8-OH-dG) assay. The results showed that the examined complexes are genotoxic, but with different degrees. The order of genotoxicity of the complexes at 10 µg/mL was: Cu(L3)(NCS)(H2O) > Zn(L3)(NCS)(H2O) > Cu(L2)(NCS) > Zn(L2)(NCS), where L2 and L3 are the conjugate bases of N-(8-quinolyl)napthaldimine and N-(anilinyl)napthaldimine, respectively. However, at the 1-µg/mL concentration, only the Cu(L3)(NCS)(H2O) complex induced significant CAs, whereas at the 0.1-µg/mL concentration, only Cu(L3)(NCS)(H2O) and Zn(L2)(NCS) complexes induced significant SCEs, compared to controls. In the urine 8-OH-dG assay, all complexes at 10 mg/100 g body weight (b.w.) were found to cause DNA damage with the following order: Cu(L3)(NCS)(H2O) > Zn(L2)(NCS) > Zn(L3)(NCS)(H2O) > Cu(L2)(NCS), whereas no significant DNA damage was observed in animals exposed to 1 and 0.1 mg/100 g b.w. (p > 0.05). In conclusion, the two examined Schiff base complexes are found to induce DNA damage, but with different degrees.

Dose-response analysis of bromate-induced DNA damage and mutagenicity is consistent with low-dose linear, nonthreshold processes

Mutagenic agents have long been inferred to act through low-dose linear, nonthreshold processes. However, there is debate about this assumption, with various studies interpreting datasets as showing thresholds for DNA damage and mutation. We have applied rigorous statistical analyses to investigate the shape of dose-response relationships for a series of in vitro and in vivo genotoxicity studies using potassium bromate (KBrO(3) ), a water ozonation byproduct that is bioactivated to a reactive species causing oxidative damage to DNA. We analyzed studies of KBrO(3) genotoxicity where no-effect/threshold levels were reported as well as other representative datasets. In all cases, the data were consistent with low-dose linear models. In the majority of cases, the data were fit either by a linear (straight line) model or a model which was linear at low doses and showed a saturation-like downward curvature at high doses. Other datasets with apparent upward curvature were still adequately represented by models that were linear at low dose. Sensitivity analysis of datasets showing upward curvature revealed that both low-dose linear and nonlinear models provide adequate fits. Additionally, a simple biochemical model of selected key processes in bromate-induced DNA damage was developed and illustrated a situation where response for early primary events suggested an apparent threshold while downstream events were linear. Overall, the statistical analyses of DNA damage and mutations induced by KBrO(3) are consistent with a low-dose linear response and do not provide convincing evidence for the presence of a threshold.

Evidence that BRCA1- or BRCA2-associated cancers are not inevitable

Inheriting a BRCA1 or BRCA2 gene mutation can cause a deficiency in repairing complex DNA damage. This step leads to genomic instability and probably contributes to an inherited predisposition to breast and ovarian cancer. Complex DNA damage has been viewed as an integral part of DNA replication before cell division. It causes temporary replication blocks, replication fork collapse, chromosome breaks and sister chromatid exchanges (SCEs). Chemical modification of DNA may also occur spontaneously as a byproduct of normal processes. Pathways containing BRCA1 and BRCA2 gene products are essential to repair spontaneous complex DNA damage or to carry out SCEs if repair is not possible. This scenario creates a theoretical limit that effectively means there are spontaneous BRCA1/2-associated cancers that cannot be prevented or delayed. However, much evidence for high rates of spontaneous DNA mutation is based on measuring SCEs by using bromodeoxyuridine (BrdU). Here we find that the routine use of BrdU has probably led to overestimating spontaneous DNA damage and SCEs because BrdU is itself a mutagen. Evidence based on spontaneous chromosome abnormalities and epidemiologic data indicates strong effects from exogenous mutagens and does not support the inevitability of cancer in all BRCA1/2 mutation carriers. We therefore remove a theoretical argument that has limited efforts to develop chemoprevention strategies to delay or prevent cancers in BRCA1/2 mutation carriers.

Genotoxicity of food preservative sodium sorbate in human lymphocytes in vitro

The genotoxic effects of antimicrobial food additive sodium sorbate (SS) was assessed by using chromosome aberrations (CAs), sister-chromatid exchanges (SCEs), and micronucleus (MN) in cultured human lymphocytes and comet assay in isolated human lymphocytes. Lymphocytes were treated with four concentrations (100, 200, 400 and 800 μg/ml) of SS as well as a negative (sterile distilled water) and a positive control (Mitomycin-C: MMC for cultured lymphocytes and H(2)O(2) for isolated lymphocytes). The result of this study indicated that SS increased the frequency of CAs at both 24 and 48 h period compared to control. When gaps were included, this increase was significant at 200, 400 and 800 μg/ml concentrations at 24 h and, at all concentrations at 48 h treatment time. When gaps were excluded, this increase was significant at only 800 μg/ml concentration at both 24 and 48 h treatments. In addition, SS increased SCEs/cell and MN frequency at 400 and 800 μg/ml concentrations at both 24 and 48 h compared to negative control. Furthermore, this additive caused DNA damage at all concentrations in isolated human lymphocytes after 1 h in vitro exposure. The present results show that SS is genotoxic to the human peripheral blood lymphocytes in vitro at the highest concentrations.

Evaluation of vitamin B12 effects on DNA damage induced by pioglitazone

Pioglitazone is a prototype of thiazolidinediones, used for the treatment of type 2 diabetes mellitus. Previous studies suggest that pioglitazone might cause DNA damage by generation of oxidative species. In this study, we investigated the mutagenic effects of pioglitazone using sister chromatid exchanges (SCEs), and chromosomal aberrations (CAs) assays in cultured human lymphocytes. In addition, oxidative DNA damage was evaluated in cells culture by measuring 8-hydroxy-2'-deoxyguanosine (8-OH-dG) marker. We also investigated the possible protective effects of vitamin B12, which is associated with DNA repair, on DNA damage induced by pioglitazone. Treatment of the human lymphocytes with pioglitazone (100μM) significantly increases the frequency of SCEs and CAs (p<0.01). In addition, significant elevation in 8-OH-dG release from lymphocytes was observed after treatment with pioglitazone (p<0.01). On the other hand, pretreatment of cultures with vitamin B12 (13.5μg/ml) protected lymphocytes from the genotoxic effect of pioglitazone. Therefore, we conclude that pioglitazone is genotoxic, and it induces chromosomal and oxidative DNA damage in cultured lymphocytes and this toxicity is prevented by pretreatment with vitamin B12.

Review of current and "omics" methods for assessing the toxicity (genotoxicity, teratogenicity and nephrotoxicity) of herbal medicines and mushrooms

ETHNOPHARMACOLOGICAL RELEVANCE

The increasing use of traditional herbal medicines around the world requires more scientific evidence for their putative harmlessness. To this end, a plethora of methods exist, more or less satisfying. In this post-genome era, recent reviews are however scarce, not only on the use of new "omics" methods (transcriptomics, proteomics, metabonomics) for genotoxicity, teratogenicity, and nephrotoxicity assessment, but also on conventional ones.

METHODS

The present work aims (i) to review conventional methods used to assess genotoxicity, teratogenicity and nephrotoxicity of medicinal plants and mushrooms; (ii) to report recent progress in the use of "omics" technologies in this field; (iii) to underline advantages and limitations of promising methods; and lastly (iv) to suggest ways whereby the genotoxicity, teratogenicity, and nephrotoxicity assessment of traditional herbal medicines could be more predictive.

RESULTS

Literature and safety reports show that structural alerts, in silico and classical in vitro and in vivo predictive methods are often used. The current trend to develop "omics" technologies to assess genotoxicity, teratogenicity and nephrotoxicity is promising but most often relies on methods that are still not standardized and validated.

CONCLUSION

Hence, it is critical that toxicologists in industry, regulatory agencies and academic institutions develop a consensus, based on rigorous methods, about the reliability and interpretation of endpoints. It will also be important to regulate the integration of conventional methods for toxicity assessments with new "omics" technologies.

Quality of bread made from ozonated wheat (Triticum aestivum L.) flour

BACKGROUND

Ozone gas could be used as a fumigant during grain and flour storage. Experiments were conducted to determine the effects of exposure to ozone and the effects of blending ozone-treated flour with control flour on flour functionality and bread-making quality.

RESULTS

Ozone treatment oxidized lipids, increased brightness and reduced the yellow hue of flour, and increased peak viscosity and setback viscosity of flour. Bread made from flour treated with ozone at 1500 mg kg(-1) for 4.5 min and bread made from flour blended with 100 g kg(-1) ozonated flour had good crust color and a whiter crumb and had more crumb cells, which resulted in a greater specific volume of the bread when compared with control flour. Flour functionality declined as ozone exposure increased beyond 9 min and as the concentration of ozonated flour increased beyond 200 g kg(-1) .

CONCLUSION

Bread made from flour exposed to ozone for 4.5 min or flour that contained 100 g kg(-1) fully ozonated flour had greater specific loaf volume and whiter crumb compared to bread made with control flour. Exposure of flour to ozone for longer times (9-45 min) and higher blends (200-1000 g kg(-1) ) deteriorated quality of bread.

Assessment of genotoxicity of waterpipe and cigarette smoking in lymphocytes using the sister-chromatid exchange assay: a comparative study

Tobacco smoking is a major world health problem. Recently, waterpipe smoking has become more popular in many countries. Although the genotoxicity associated with cigarette smoking has been extensively investigated, studies evaluating such toxicity in waterpipe users are still lacking. In this study, we examined the genotoxicity of waterpipe smoking in lymphocytes compared with the genotoxicity of cigarette smoking. Genotoxicity was evaluated using the sister chromatid exchanges (SCEs) assay. Fifty waterpipe smokers and 18 healthy nonsmokers participated in this study. Additionally, 18 heavy cigarette smokers (CS) were recruited for comparison. The results show that waterpipe smoking and cigarette smoking significantly increase the frequencies of SCEs (P < 0.01) compared with those of nonsmokers, indicating the genotoxic effect of tobacco smoking. In addition, frequencies of SCEs were significantly higher among waterpipe smokers compared with CS (P < 0.01), indicating that waterpipe smoking is more genotoxic than cigarette smoking. Moreover, the frequency of SCEs increased with the extent of waterpipe use. In conclusion, waterpipe smoking is genotoxic to lymphocytes and the magnitude of its genotoxicity is higher than that induced by regular cigarette smoking.

Possible involvement of oxidative stress in potassium bromate-induced genotoxicity in human HepG2 cells

Potassium bromate (KBrO(3), PB) is a by-product of ozone used as disinfectant in drinking water. And PB is also a widely used food additive. However, there is little known about its adverse effects, in particular those related to its genotoxicity in humans. The aim of this study was to investigate the genotoxic effects of PB and the underlying mechanisms, using human hepatoma cell line, HepG2. Exposure of the cells to PB caused a significant increase of DNA migration in single cell gel electrophoresis (SCGE) assay and micronuclei (MN) frequencies in micronucleus test (MNT) at all tested concentrations (1.56-12.5 mM and 0.12-1 mM), which suggested that PB-mediated DNA strand breaks and chromosome damage. To indicate the role of antioxidant in those effects, DNA migration was monitored by pre-treatment with hydroxytyrosol (HT) as an antioxidant in SCGE assay. It was found that DNA migration with pre-treatment of HT was dramatically decreased. To elucidate the genotoxicity mechanisms, the study monitored the levels of reactive oxygen species (ROS), glutathione (GSH) and 8-hydroxydeoxyguanosine (8-OHdG). PB was shown to induce ROS production (12.5 mM), GSH depletion (1.56-12.5 mM) and 8-OHdG formation (6.25-12.5 mM) in HepG2 cells. Moreover, lysosomal membrane stability and mitochondrial membrane potential were further studied for the mechanisms of PB-induced genotoxicity. A significant increase was found in the range of 6.25-12.5 mM in lysosomal membrane stability assay. However, under these PB concentrations, we were not able to detect the changes of mitochondrial membrane potential. These results suggest that PB exerts oxidative stress and genotoxic effects in HepG2 cells, possibly through the mechanisms of lysosomal damage, an earlier event preceding the oxidative DNA damage.

Genotoxic effects of white fluorescent light on human lymphocytes in vitro

Sources of light beams such as white fluorescent light, are present in our daily life to meet the needs of life in the modern world. This study was conducted with the objective of determining the possible genotoxic, cytotoxic and aneugenic effects caused by this agent in different stages of the cell cycle (G0/early G1, S, and late G2), using different cytogenetic parameters (sister chromatid exchanges--SCE, chromosome aberrations--CA, and detection of aneugenic effects) in lymphocytes from temporary cultures of human peripheral blood. WFL showed a genotoxic effect in vitro, expressed by an increase in the frequency of SCE's, regardless of the cell cycle stage. However, no increase in the frequency of CAs was observed. In addition, disturbances in cell cycle kinetics and chromosomal segregation were also observed. Taken together, such data may contribute to a better understanding and a different management in the use of phototherapy for some pathological conditions.

Clastogenic effects of food additive citric acid in human peripheral lymphocytes

Clastogenic properties of the food additive citric acid, commonly used as an antioxidant, were analysed in human peripheral blood lymphocytes. Citric acid induced a significant increase of chromosomal aberrations (CAs) at all the concentrations and treatment periods tested. Citric acid significantly decreased mitotic index (MI) at 100 and 200 mug ml(-1) concentrations at 24 h, and in all concentrations at 48 h. However, it did not decrease the replication index (RI) significantly. Citric acid also significantly increased sister chromatid exchanges (SCEs) at 100 and 200 mug ml(-1) concentrations at 24 h, and in all concentrations at 48 h. This chemical significantly increased the micronuclei frequency (MN) compared to the negative control. It also decreased the cytokinesis-block proliferation index (CBPI), but this result was not statistically significant.