Assessment of the ameliorative effect of curcumin on pendimethalin-induced genetic and biochemical toxicity.

The present study aimed to assess the toxic effects of pendimethalin herbicide and protective role of curcumin using the Allium test on cytological, biochemical and physiological parameters. The effective concentration (EC50) of pendimethalin was determined at 12 mg/L by the root growth inhibition test as the concentration reducing the root length by 50%. The roots of Allium cepa L. was treated with tap water (group I), 5 mg/L curcumin (group II), 10 mg/L curcumin (group III), 12 mg/L pendimethalin (group IV), 12 mg/L pendimethalin + 5 mg/L curcumin (group V) and 12 mg/L pendimethalin + 10 mg/L curcumin (group VI). The cytological (mitotic index, chromosomal abnormalities and DNA damage), physiological (rooting percentage, root length, growth rate and weight gain) and oxidative stress (malondialdehyde level, superoxide dismutase level, catalase level and glutathione reductase level) indicators were determined after 96 h of treatment. The results revealed that pendimethalin treatment reduced rooting percentage, root length, growth rate and weight gain whereas induced chromosomal abnormalities and DNA damage in roots of A. cepa L. Further, pendimethalin exposure elevated malondialdehyde level followed by antioxidant enzymes. The activities of superoxide dismutase and catalase were up-regulated and glutathione reductase was down-regulated. The molecular docking supported the antioxidant enzymes activities result. However, a dose-dependent reduction of pendimethalin toxicity was observed when curcumin was supplied with pendimethalin. The maximum recovery of cytological, physiological and oxidative stress parameters was recorded at 10 mg/L concentration of curcumin. The correlation studies also revealed positive relation of curcumin with rooting percentage, root length, weight gain, mitotic activity and glutathione reductase enzyme level while an inverse correlation was observed with chromosomal abnormalities, DNA damage, superoxide dismutase and catalase enzyme activities, and lipid peroxidation indicating its protective effect.

A comprehensive weight of evidence assessment of published acetaminophen genotoxicity data: Implications for its carcinogenic hazard potential.

In 2019, the California Office of Environmental Health Hazard Assessment initiated a review of the carcinogenic hazard potential of acetaminophen, including an assessment of its genotoxicity. The objective of this analysis was to inform this review process with a weight-of-evidence assessment of more than 65 acetaminophen genetic toxicology studies that are of widely varying quality and conformance to accepted standards and relevance to humans. In these studies, acetaminophen showed no evidence of induction of point or gene mutations in bacterial and mammalian cell systems or in in vivo studies. In reliable, well-controlled test systems, clastogenic effects were only observed in unstable, p53-deficient cell systems or at toxic and/or excessively high concentrations that adversely affect cellular processes (e.g., mitochondrial respiration) and cause cytotoxicity. Across the studies, there was no clear evidence that acetaminophen causes DNA damage in the absence of toxicity. In well-controlled clinical studies, there was no meaningful evidence of chromosomal damage. Based on this weight-of-evidence assessment, acetaminophen overwhelmingly produces negative results (i.e., is not a genotoxic hazard) in reliable, robust high-weight studies. Its mode of action produces cytotoxic effects before it can induce the stable, genetic damage that would be indicative of a genotoxic or carcinogenic hazard.

In vitro and in vivo genotoxicity assessment of ferric ferrocyanide and potassium-cobalt ferrocyanide.

Ferric hexacyanoferrate(II) (Fe4[Fe(CN)6]3), i.e. Prussian blue (PB) has been used for many years to remove from the body the two toxic isotopes of cesium and thallium following irradiation. Recently, potassium cobalt hexacyanoferrate(II) (K2COFe(CN)6), which has shown a better efficacy for decontamination, is also being considered for use to enhance the elimination of cesium isotopes. In view to its preclinical and clinical development, in vitro and in vivo GLP-compliant genotoxicity studies were carried out on this product as well as on PB for comparison. Several tests dissecting the main events leading to genotoxicity, i.e. mutagenicity and chromosomal aberrations, both structural and quantitative were implemented. In vitro, no mutagenic effect was observed in the Ames test but both compounds were positive in the mouse lymphoma assay on TK locus and induced clastogenic effects in the in vitro chromosomal aberrations test on human lymphocytes, either in absence or in presence of metabolic activation. K-Co-ferrocyanide was also assayed in vivo in the mouse bone marrow micronucleus assay and PB was assessed for DNA fragmentation in the rodent Comet assay in both glandular stomach and colon. In the in vivo micronucleus mouse bone marrow, K-Co-ferrocyanide did not display any genotoxic activity up to 2000 mg/kg/d (x2) by oral route. In opposite, PB induced a significant increase in DNA fragmentation both in the glandular stomach and in the colon of rat treated 3 times with intake ranging from 2000 to 500 mg/kg. PB should be considered as an in vivo mutagen as well as Potassium cobalt hexacyanoferrate(II) since the in vitro genotoxicity profiles of both ferrocyanides are quite similar. Their use as cesium/ thallium decontamination agents in human should be assessed following a benefit/risk approach to enable a robust decision-making.

Genotoxicity as a toxicologically relevant endpoint to inform risk assessment: A case study with ethylene oxide.

The purpose of the present investigation is to analyze the in vivo genotoxicity dose-response data of ethylene oxide (EO) and the applicability of the derived point-of-departure (PoD) values when estimating permitted daily exposure (PDE) values. A total of 40 data sets were identified from the literature, and benchmark dose analyses were conducted using PROAST software to identify a PoD value. Studies employing the inhalation route of exposure and assessing gene or chromosomal mutations and chromosomal damage in various tissues were considered the most relevant for assessing risk from EO, since these effects are likely to contribute to adverse health consequences in exposed individuals. The PoD estimates were screened for precision and the values were divided by data-derived adjustment factors. For gene mutations, the lowest PDE was 285 parts per trillion (ppt) based on the induction of lacI mutations in the testes of mice following 48 weeks of exposure to EO. The corresponding lowest PDE value for chromosomal mutations was 1,175 ppt for heritable translocations in mice following 8.5 weeks of EO exposure. The lowest PDE for chromosomal aberrations was 238 ppt in the mouse peripheral blood lymphocytes following 48 weeks of inhalation exposure. The diverse dose-response data for EO-induced genotoxicity enabled the derivation of PoDs for various endpoints, tissues, and species and identified 238 ppt as the lowest PDE in this retrospective analysis.

In vitro and in vivo assessment of the genotoxic effects of ceric ammonium nitrate and 1,3-propane sultone.

A variety of methods have been developed for accurate and systematic evaluation of chemical genotoxicity. Ceric ammonium nitrate (CAN) and 1,3-propane sultone (1,3-PS) have been extensively applied in industrial fields. Although 1,3-PS, but not CAN, has been reported as a potent carcinogen, systematic assessment of the genotoxic properties of these chemicals has not been conducted. The purpose of this study was to establish a decision tree for evaluating genotoxicity based on the good laboratory practices (GLP) system using 1,3-PS and CAN as test chemicals. In vitro studies were performed including the bacterial reverse mutation assay, chromosomal aberration assay, and micronucleus assay. We conducted in vivo studies using a combined micronucleus and alkaline comet (MN-CMT) assay and the Pig-a gene mutation assay, which is a promising method for detecting gene mutations in vivo. CAN showed negative responses in all in vitro genotoxicity assays and the in vivo combined MN-CMT assay. Meanwhile, 1,3-PS had positive results in all in vitro and in vivo genotoxicity assays. In this study, we confirmed the genotoxicity of 1,3-PS and CAN using both in vitro and in vivo assays. We propose a decision tree for evaluating chemical-induced genotoxicity.

In vitro genotoxicity assessment and comparison of cerium (IV) oxide micro- and nanoparticles.

Cerium (IV) oxide (CeO2), which is used as a biomaterial, has wide application in areas such as the biomedical, glass polishing, electronic, automotive, and pharmacology industries. Comparing with the literature, in this study, the genotoxic effects of cerium (IV) oxide microparticles (COMPs) and cerium (IV) oxide nanoparticles (CONPs) were investigated for the first time in human peripheral blood cultures at concentrations of 0.78, 1.56, 3.125, 6.25, 12.5, 25, and 50 ppm for 72 h under in vitro conditions. Particle sizes of COMPs and CONPs were determined using scanning electron microscopic analysis. Micronucleus and chromosome aberration tests were used to determine the genotoxicity of COMPs and CONPs. The average particle sizes of COMPs and CONPs were approximately 148.25 and 25.30 nm, respectively. It was determined that CeO2 particles in both micro and nano sizes were toxic at all concentrations compared to the negative control group (distilled water). Importantly, COMPs and CONPs were genotoxic even at the lowest concentration (0.78 ppm). Comparing particle sizes, the data indicated that COMPs were more toxic than CONPs. The results suggest that genotoxicity of COMPs and CONPs may be a function of applied concentrations and particle sizes.

Initial hazard assessment of 1,4-dichlorobutane: Genotoxicity tests, 28-day repeated-dose toxicity test, and reproductive/developmental toxicity screening test in rats.

1,4-Dichlorobutane (1,4-DCB) is used as raw materials for drugs, pesticides, fragrances, and chemical fibers, and being used as a solvent. Its toxicity data was insufficient for screening assessment under the Japanese Chemical Substances Control Law. We conducted toxicity tests and hazard classification for screening assessment 1,4-DCB showed negative in the Ames test, positive in the in vitro chromosomal aberrations test with metabolic activation, and negative in the in vivo mouse bone-marrow micronucleus test. The 28-day repeated-dose toxicity study, where male and female rats were administered 1,4-DCB by gavage at 0, 12, 60, and 300 mg/kg/day, showed significant effects on the liver and pancreas from 12 mg/kg/day and kidney at 300 mg/kg/day. Based on periportal hepatocellular hypertrophy and decreased zymogen granules in pancreas, the lowest observed adverse effect level (LOAEL) of 12 mg/kg/day was obtained. The reproductive/developmental toxicity screening study, in which male and female rats were administered 1,4-DCB by gavage at dose of 0, 2.4, 12, and 60 mg/kg/day for 42-46 days, showed that the delivery index was decreased at 60 mg/kg/day without maternal toxicity. Based on the general toxicity, we classified this chemical as hazard class 2, with a D-value (Derived No Effect Level) of 0.002 mg/kg/day.

The Potential Risk Assessment of Phenoxyethanol with a Versatile Model System.

In this study, the toxic effects of phenoxyethanol (Phy-Et), which is widely used in cosmetic industry, has been investigated with Allium test by means of physiological, cytogenetic, anatomical and biochemical parameters. To determine the changes in physiological reactions weight gain, relative injury rate, germination percentage and root length were investigated. Malondialdehyde, superoxide dismutase, glutathion and catalase levels were analyzed as biochemical parameters for determining the presence of oxidative stress. Mitotic index, micronucleus and chromosomal abnormality frequencies were studied as cytogenetic evaluation and the anatomical changes in root tip cells were investigated by cross sections. Changes in surface polarity and wettability were investigated by taking contact angle measurements of pressed root preparations. The mechanism of toxicity has been tried to be explained by these contact angles and this is the first study using contact angle measurements in toxicity tests. Consequently, exposure to Phy-Et resulted in a decrease in all measured physiological parameters and in mitotic index. In contrast, significant increases in the micronucleus and chromosomal abnormality frequencies were observed and the most significant toxic effect was found in 10 mM Phy-Et treated group. Phy-Et application induced oxidative damage and caused a significant increase in malondialdehyde level and a decrease in glutathione level compared to control group. Also a response occured against oxidative damage in superoxide dismutase and catalase activity and the activities increased in 2.5 mM and 5 mM Phy-Et treated groups and decreased in 10 mM Phy-Et treated groups. Furthermore, Phy-Et treatment resulted in some anatomical damages and changes such as necrosis, cell deformation and thickening of the cortex cell wall in root tip meristem cells of A. cepa. In the contact angle measurements taken against water, it was found that the wettability and hydrophilicity of the root preparations treated with Phy-Et were reduced, and this was the explanation of the growth abnormalities associated with water uptake. As a result, it was found that Phy-Et application caused toxic effects on many viability parameters and A. cepa test material was a reliable biomarker in determining these effects.

Assessment of titanium dioxide nanoparticles toxicity via oral exposure in mice: effect of dose and particle size.

Objective: The aim of the present work is to evaluate the toxicity of titanium dioxide nanoparticles (TiO2NPs) according to their doses and particle sizes. Materials and methods: The effect of five days oral administration of TiO2NPs (21 and 80 nm) with different doses (50, 250 and 500 mg/kg body weight) was assessed in mice via measurement of oxidative stress markers; glutathione (GSH), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA) and nitric oxide (NO), liver function indices; aspartate and alanine aminotransferases (AST and ALT), chromosomal aberrations and liver histopathological pattern. Results: The results revealed drastic alterations in all the measured parameters and showed positive correlation with the gradual dose increment. In addition, the smaller particle size of TiO2NPS (21 nm) had more adverse effect in all the selected biochemical parameters, genetic aberrations and histological investigations. Conclusions: Toxicity of TiO2NPs increases in a dose-dependent manner and vice versa with particles size. The evaluated biomarkers are good indicators for TiO2NPs toxicity. More detailed studies are required before the recommendation of TiO2NPS as food additives.

Assessment of anticytotoxic effect of lichen Cladonia foliacae extract on Allium cepa root tips.

The aim of this study is to investigate the protective effect of lichen Cladonia foliacae (Huds.) (CF) on hydrogen peroxide (H2O2)-induced toxicity through cell death, chromosome aberrations, mitotic index, oxidative stress parameters, and DNA damage in a Allium cepa root meristematic cells. Any chemical was not given for control group. Two doses of H2O2 (3 and 7%) were given to the roots for 1 h and the root tips were treated with CF water extract (50 and 100 µL) with increasing times for treatment groups. The roots were taken from control and treatment groups, and mitotic index, cell death, and chromosome aberrations were performed by light microscope. Changing antioxidant capacity of roots was revealed by FRAP and TEAC assay. Also, DNA damage was measured by comet assay and RAPD-PCR technique. Chromosome aberration values were obtained with increasing concentrations with longer treatment times, such as chromosome bridge, vagrant, and polyploidy in both groups. Increasing exposure doses of H2O2 caused decreasing mitotic index values at 72 h. TEAC and FRAP assay demonstrated that roots' capacity of antioxidant was altered by increasing concentrations of H2O2. The tail DNA% and tail length significantly increased in all exposure times when compared to control group. Three and seven percent of H2O2 caused the genotoxic effect on genetic material at 72 h according to RAPD-PCR technique. Increasing the doses of H2O2 resulted in increased toxicity to all studied parameters of A. cepa, but CF extract altered all changing parameters of A. cepa root cell. The H2O2 tested in this study have cytotoxic and mutagenic potential, but extract of CF was protective against H2O2 caused toxicological changes. But, it did not protect completely in the A. cepa root meristematic cells.

Potential of the Bioinspired CaCO3 Microspheres Loaded with Tetracycline in Inducing Differential Cytotoxic Effects toward Noncancerous and Cancer Cells: A Cytogenetic Toxicity Assessment Using CHO Cells in Vitro.

Calcium carbonate (CaCO3)-based materials as feasible pH-sensitive drug carriers, which can actively dissolve in an acidic microenvironment of cancer cells, are finding increasing importance. This has drawn our interest in the development of a bioinspired polypeptide- mediated method to design calcium carbonate microspheres loaded with tetracycline (CaCO3-TC) with an aim to explore its safe application in cancer therapeutics. Its therapeutic application in cancer patients essentially demands its safety information on the normal cells. Herein our study presents the in vitro genetic toxicological information on CaCO3-TC using noncancerous mammalian CHO cells in comparison to bare TC at three different concentrations (100, 200, and 300 µM) selected based on the cytotoxicity data (MTT). Assessment of various end points like chromosome aberrations, micronucleus, mitotic index and effects on cell cycle distribution after 24 h post-treatment demonstrates a significant reduction in clastogenic ( P < 0.001), aneugenic potential ( P < 0.05), and nonmitotoxic nature of CaCO3-TC than that of bare TC. Noticeably, as inferred from the FACS analysis on cancer cells, G2/M phase accumulation in breast cancer cells (MDA-MB-231), and at G1 phase in cervical cancer cells (HeLa) reveal its potential anticancer property. On the other hand, the genotoxicity studies illustrate protective effects of CaCO3-TC on noncancerous cells. While the pH-dependent dissolution property of the CaCO3 matrix encasing tetracycline results in higher toxicity on cancer cells, the near neutral pH in the case of normal cells prevents complete dissolution of CaCO3 thereby not allowing the encapsulated TC to adequately interact with the cells. Therefore, thus assembled CaCO3 spheres not only provide a way for facile encapsulation of tetracycline under mild conditions but also result in an effective matrix for differential toxicity toward normal and cancer cells justifying its clinical development as a novel target-specific drug in therapeutic applications for metastatic cancers.

Assessment of cytotoxic and genotoxic effects of enniatin-A in vitro.

Enniatin A (EN-A) is a Fusarium mycotoxin which is a common contaminant in grains and especially in maize and it causes serious loss of product. The aim of this study was to investigate the cytotoxic effects using 3-(4,5-dimethylthiazolyl-2)-2,5 diphenyltetrazolium bromide (MTT) assay in human cervix carcinoma (HeLa) cell line, and genotoxic effects of EN-A using chromosome aberrations (CAs), sister chromatid exchanges (SCEs), micronuclei (MN) and comet assays in human lymphocytes. The cells were treated with 0.07, 0.14, 0.29, 0.57, 1.15, 2.29, 4.59 and 9.17 µM concentrations of EN-A. It exhibited cytotoxic effects in HeLa cell lines especially when the concentrations were increased. The half-inhibitory value (IC50) was determined as 1.15 µM concentration for 24 h and 0.57 µM concentration for 48 h. However, EN-A failed to affect the frequency of CAs, SCEs and MN in human lymphocytes. Only a slight increase was observed in the frequency of SCEs at 0.57 µM concentration over 48 h. The replication (RI) and nuclear division (NDI) indices were not affected. On the contrary, EN-A decreased the mitotic index (MI) significantly at all concentrations compared to the negative control and solvent control (except at 0.29 µM for 24 h, and except at 0.14, 0.29 and 0.57 µM for 48 h). Treatments over 2.29 µM showed toxic effects in human lymphocytes. EN-A significantly increased comet tail intensity (except at 0.07 and 0.57 µM) in isolated human lymphocytes. The results of this study demonstrate that EN-A has an obvious cytotoxic effect especially when the EN-A concentration was increased. In addition, EN-A could exhibit a mild genotoxic effect.

Initial hazard assessment of 4-benzylphenol, a structural analog of bisphenol F: Genotoxicity tests in vitro and a 28-day repeated-dose toxicity study in rats.

4-Benzylphenol (CAS No. 101-53-1), a structural analog of bisphenol F, has estrogenic activity in vitro and in vivo, as is the case with bisphenol F. 4-Benzylphenol is used in plastics and during organic synthesis. Since its safety is largely unknown, we conducted toxicity tests as part of screening risk assessment in an existing chemical safety survey program. Based on results of the Ames test and the chromosomal aberration test using Chinese hamster lung cells (OECD TG 471 and 473), 4-benzylphenol was determined to be non-genotoxic in vitro. In a 28-day repeated-dose toxicity study, Crl:CD (SD) rats were administrated 4-benzylphenol by gavage at 0, 30, 150, or 750 mg/kg/day (OECD TG 407). Consequently, body weight was lower in males at 750 mg/kg/day. In the liver, relative organ weights were increased in both sexes at 750 mg/kg/day, and centrilobular hepatocellular hypertrophy was observed in males at 150 and 750 mg/kg/day. In the forestomach, hyperkeratosis and hyperplasia of squamous cells were observed in males at 150 and 750 mg/kg/day, and in females at 750 mg/kg/day. Based on these results, we identified the NOAEL for 4-benzylphenol as 30 mg/kg/day, with a hazard assessment value (D-value) of 0.05 mg/kg/day corresponding to hazard class 3.

Assessment of protective potential of Nigella sativa oil against carbendazim- and/or mancozeb-induced hematotoxicity, hepatotoxicity, and genotoxicity.

Nigella sativa oil (NSO) possesses antioxidant activity. However, its protective role against the hazards of fungicides has been poorly studied. Therefore, the present work aimed at determining the ameliorative potential of NSO against hepatotoxicity induced by carbendazim (CBZ) and/or mancozeb (MNZ) in female rats. In the present study, about 120 adult female Sprague-Dawley rats were randomly divided into eight equal groups. One group of animals was kept as a negative control (Gp. 1); groups 2, 3 and 4 orally received CBZ (200 mg/kg body wt) and/or MNZ (300 mg/kg body wt) daily for 2 weeks (positive groups). In order to assess the hepatoprotective potential of NSO, in comparison with NSO-treated rats (Gp. 5), groups 6, 7 and 8 were CBZ- and/or MNZ-exposed groups pre-treated orally with NSO (2 ml/kg body wt) daily for 2 weeks (prophylactic groups). All groups were kept further for 15 days without medications to observe the withdrawal effect. At the end of exposure and withdrawal periods, the body weight of all experimental rats was recorded and blood samples were collected for hematological, clinico-biochemical, and micronucleus assays. The animals were then sacrificed, and the liver and bone marrow were harvested for oxidative stress bioassay, chromosomal aberrations, DNA fragmentation, and histopathological examinations. The results suggested that pre-treatment with NSO remarkably diminished CBZ- and MNZ-induced macrocytic hypochromic anemia, leukocytosis, lymphocytosis, eosinophilia, and neutropenia. Besides, it also minimized the elevated liver enzymes, lipid peroxidation, micronucleus incidence, DNA damage, and chromosomal aberration frequency. Conversely, NSO significantly stimulated the CBZ- and/or MNZ-induced antioxidant system suppression. The NSO also normalized the hepatic structural architecture. As far as withdrawal effect is concerned, there was almost disappearance of the bad effects of these fungicides and the values were close to the normal range especially with the use of NSO. Ultimately, the results revealed that N. sativa oil is an effective hepatoprotective agent due to its genoprotective and free radical scavenging activities.

An insight into the genotoxicity assessment studies in dipterans.

The dipterans have been widely utilized in genotoxicity assessment studies. Short life span, easy maintenance, production of large number of offspring in a single generation and the tissues with appropriate cell populations make these flies ideal for studies associated to developmental biology, diseases, genetics, genetic toxicology and stress biology in the group. Moreover, their cosmopolitan presence makes them suitable candidate for ecological bio-monitoring. An attempt has been made in the present review to reveal the significance of dipteran flies for assessing alterations in genetic content through various genotoxicity biomarkers and to summarize the gradual advancement in these studies. Recent studies on genotoxicity assays in dipterans have opened up a broader perspective for DNA repair related mechanistic studies, pre-screening of chemicals and environmental bio-monitoring. Studies in dipterans, other than Drosophila may be helpful in using them as an alternative model system for assessment of genotoxicity, especially at the gene level and further extension of these studies give a future insight to develop new strategies for maintaining environment friendly limits of the toxicants.

Synthesis and characterization of silver nanoparticles using Caesalpinia pulcherrima flower extract and assessment of their in vitro antimicrobial, antioxidant, cytotoxic, and genotoxic activities.

Caesalpinia pulcherrima flower extract mediated synthesis of silver nanoparticles was attempted in the present work including optimization of some procedure parameters. Characterization of synthesized silver nanoparticles was done by various spectral analyses. The size of synthesized silver nanoparticles was 12 nm and they were spherical in shape. The green synthesized silver nanoparticles were further evaluated for antimicrobial, antioxidant, cytotoxic, and genotoxic activities; they showed good antimicrobial, antioxidant, and cytotoxic effects. Genotoxic study revealed non-toxic nature at lower concentration. Overall results suggest that the synthesized silver nanoparticles have pronounced applicability in pharmaceutical and biomedical field.

The influence of blood storage time and general anaesthesia on chromosomal radiosensitivity assessment.

The micronucleus assay (MN assay) is a well-established assay in genetic toxicology, biomonitoring of mutagen-exposed populations and chromosomal radiosensitivity testing. To evaluate the effect of storage time on the chromosomal radiosensitivity assessment in lymphocytes, micronuclei (MN) yields in blood samples received and processed on the same day were compared with MN yields obtained when blood cultures were set up 24 and 48h after blood sampling. Furthermore, the influence of general anaesthesia on MN and binucleated cells (BN) yields in the MN assay was considered. Blood samples of 10 healthy donors were irradiated and blood cultures were set up during the same day of blood sampling or with a delay of 24 or 48h. The MN assay was also performed on two blood samples from 60 women undergoing breast surgery. The first blood sample was taken before general anaesthesia and the second sample, 2h after anaesthesia induction. Fifty percent of the blood samples were transported to the cytogenetics lab within 2h while the other 50% reached the lab after 24h. The results of this study show a decrease in BN and an increase in MN yields with increasing storage time before irradiation and setting up of the MN assay for both healthy controls and patients. The administration of general anaesthesia in patients resulted in lower BN yields, higher spontaneous MN yields but no differences in radiation-induced MN yields. In conclusion, this study indicates that the time between blood sampling and the in vitro irradiation of the samples for the MN assay influences the MN yields. Delays of more than 24h should be avoided. To assess chromosomal radiosensitivity in patients, blood samples should be taken before induction of general anaesthesia as anaesthesia can have an impact on the reliability of the MN results.

Genotoxicity assessment of cobalt chloride in Eisenia hortensis earthworms coelomocytes by comet assay and micronucleus test.

Cobalt and its different compounds are extensively used worldwide and considered as possible environmental pollutant. Earthworms are useful model organism and its different species are used to monitor soil pollution. No study has been found to detect cobalt chloride (CoCl2) genotoxicity in earthworms. So, current study aimed to evaluate CoCl2 induced genotoxicity in Eisenia hortensis earthworms coelomocytes by alkaline comet assay (CA) and micronucleus (MN) test. The earthworms (n = 10 for each group) were exposed to different series of CoCl2 concentrations (100 ppm, 200 ppm, 300 ppm, 400 ppm, 500 ppm, 600 ppm) to find LD50. The LD50 for CoCl2 was found at 226 ppm. Then, doses of LD50/2, LD50 and 2XLD50 for 48 h were used. CA and MN demonstrated the significant increase (P < 0.05) in DNA damage and chromosomal aberrations. Dose dependent relationship was found. Highest DNA damage and chromosomal aberrations were noticed at 2XLD50. The results concluded that CoCl2 induced DNA damage, cytokinesis failure and chromosomal aberrations in E. hortensis earthworms.

In vitro risk assessment of usnic acid.

Lichens are symbiotic organisms composed of fungi and algae and are very common in Turkey. Lichen secondary metabolites are mainly phenolic compounds produced by fungal partner of lichen symbiosis. Usnic acid (UA) is one of the most common lichen metabolites, and it was reported that to be effective for a wide range of pharmacological purposes including antiviral, antitumor, and antiprotozoal. However, there are limited data on the genotoxic and antioxidant effects of UA in cultured human peripheral blood cells. Therefore, the aim of this thesis study was to investigate the genetic and oxidative effects of UA in cultured human blood cells (n = 5). The UA was added into culture tubes at various concentrations (0-200 µg/ml). Chromosomal aberrations (CA) and micronuclei (MN) tests were performed for genotoxic damage influences estimation. In addition, biochemical parameters (total antioxidant capacity (TAC) and total oxidative status (TOS)) were examined to determine oxidative effects. In our in vitro test systems, it was observed that UA had no mutagenic effects on human lymphocytes. Furthermore, our results indicated that low concentrations (1 and 5 µg/ml) of UA caused increases of TAC levels in cultured human blood cells. And, the TOS levels were not changed (p > 0.05) when all the concentrations (except for 200 µg/ml) of UA were applied. In conclusion, UA can be a new resource of therapeutics as recognized in this study with their nonmutagenic and antioxidant features.