Saccharomyces Cerevisiae D7 Research Articles

Anise essential oil immobilized in chitosan microparticles: a novel bactericidal material for food protection.

Foodborne infections in humans are one of the major concerns of the food industries, especially for minimally processed foods (MPF). Thereby, the packaging industry applies free chlorine in the sanitization process, ensuring the elimination of any fecal coliforms or pathogenic microorganisms. However, free chlorine's propensity to react with organic matter, forming toxic compounds such as trihalomethanes and haloacetic acid. Therefore, the present work aimed to synthesize a novel organic biomaterial as an alternative to free chlorine. Chitosan microparticles were produced, with Pimpinella anisum (anise) essential oil immobilized in the biopolymer matrix (MPsQTO). The characterization of this biomaterial was done through GC-MS/MS, FT-IR, and SEM. Antimicrobial assays proved that the MPsQTO presented antibacterial activity for Escherichia coli, Salmonella typhi, Pseudomonas aeruginosa, and Bacillus subtilis at 300 µL mL-1 of concentration. The fluorescence microscope also showed the MPsQTO targets the cytoplasmatic membrane, which is responsible for cell death in the first minutes of contact. Studies with the mutant B. subtilis (amy::pspac-ftsZ-gfpmut1) and the Saccharomyces cerevisiae D7 also proved that the biomaterial did not affect the genetic material and did not have any mutagenic/carcinogenic effect on the cells. The sanitization assays with pumpkin MPF proved that the MPsQTO is more effective than free chlorine, increasing the shelf-life of the MPF. Consequently, the novel biomaterial proposed in this work is a promising alternative to traditional chemical sanitizers.

An investigation of the antioxidant potential and bioaccumulated minerals in Tuber borchii and Tuber maculatum mycelia obtained by submerged fermentation.

Submerged fermentation of Tuber borchii and T. maculatum was performed to produce mycelia towards evaluating their bioactive potential and probable toxicity. Truffle mycelia had been mostly explored for biopolymers previously. Methanolic extraction yield, polyphenol content, and flavonoid content varied with species and period of fermentation. In vitro DPPH, FRAP, ABTS and ORAC radical scavenging activity of mycelial extracts of T. maculatum and T. borchii at 7 and 10 days of bioreactor fermentation corroborated with phenolics content. Absence of toxicity and antimutagenicity in lag and log phases in Saccharomyces cerevisiae D7 cells supported possibly safe nutraceutical use of mycelia of both truffles. Mineral content showed variation with species and fermentation time for macro- (calcium, potassium, phosphorus, sodium, iron, magnesium, and manganese) and trace elements (zinc, selenium, copper, chromium, and nickel). Mineral bioaccumulation can be explored for food-fortification applications. The demonstrated activities and detected constituents show potential applications in food, pharmaceutical, cosmetics and nutraceuticals.

133 - Antioxidant and antimutagenic activities of propolis from the Melipona quadrifasciata anthidioides (Hymenoptera, Apidae)

Melipona quadrifasciata anthidioides is a specie of stingless bee able to produce propolis, a product known to have different biological activities. Propolis is obtained from the mixture of plant exudates and mandibular secretions of the bees, which confers a wide diversity of bioactive compounds. The objective of this study was to evaluate the antioxidant and antimutagenic activities of ethanol extracts of propolis obtained from the M. q. anthidioides. The antioxidant action was evaluated in the wildtype N2 strain of the nematode Caenorhabditis elegans, being incubated with the juglone oxidizing agent for 6 hours. To investigate the antimutagenic potential of extract, strains of Saccharomyces cerevisiae D7 diploid (ATCC 201137) were incubated with the mutagenic agent ethyl methanesulfonate. As results, the nematodes treated with 100 μg/mL of propolis extract presented 10.9 ± 3.4% of viability, after 6 hours of incubation with the oxidizing agent. In this period, nematodes incubated only with juglone showed mortality of all individuals. In addition, the propolis extract presented antimutagenic activity, resulting in a reduction in the number of revertant colonies in 82.9 ± 0.5% and to reduce the amount of mutant colonies by 93.3 ± 0.6 %, at a concentration of 3.0 mg/mL, compared to the control group. In conclusion, this study shows that the propolis produced by M. q. anthidioides presents potential to be used in the prevention or treatment of diseases related to oxidative stress and mutagenesis.

Nutraceutical potential of hemp (Cannabis sativa L.) seeds and sprouts

In this study the antioxidant effect of Cannabis sativa L. seeds and sprouts (3 and 5 days of germination) was evaluated. Total polyphenols, flavonoids and flavonols content, when expressed on dry weight basis, were highest in sprouts; ORAC and DPPH (in vitro assays), CAA-RBC (cellular antioxidant activity in red blood cells) and hemolysis test (ex vivo assays) evidenced a good antioxidant activity higher in sprouts than in seeds. Untargeted analysis by high resolution mass spectrometry in negative ion mode allowed the identification of main polyphenols (caffeoyltyramine, cannabisin A, B, C) in seeds and of ω-6 (linoleic acid) in sprouts. Antimutagenic effect of seeds and sprouts extracts evidenced a significant decrease of mutagenesis induced by hydrogen peroxide in Saccharomyces cerevisiae D7 strain. In conclusion our results show that C. sativa seeds and sprouts exert beneficial effects on yeast and human cells and should be further investigated as a potential functional food.

Study of gamma radiation induced damages and variation of oxygen enhancement ratio with radiation dose using Saccharomyces cerevisiae

In the present study, an attempt has been made to quantify Oxygen Enhancement Ratio (OER) and variation of OER as a function of dose with experimental and theoretical formulations using Saccharomyces cerevisiae D7, X2180 and rad 52. The study confirms that, the variation of OER with dose depends upon type of cell and repair proficiency of cells. A theoretical model has been formulated to estimate OER values. With the help of this model, OER value for any dose can be calculated in the exponential region of the survival curve without actually extending the experiment in that dose region.

Antimutagenic properties of several kinds of rice as tested upon yeast strainSaccharomyces cerevisiaeD7

The aim of this work was to study antimutagenic and antioxidant properties of water extracts of various types of rice. Antioxidant activity, total phenolic andflavonoid contents were measured spectrophotometrically. Individual phenolics — catechins, catechin gallates, ferulic acid — were analysed by HPLC/PDA. Antimutagenic activity of rice extracts was tested using unicellular eukaryotic yeast strain Saccharomyces cerevisiae D7 the first time.Non-processed rice types contained substantially higher amount of soluble total and individual phenolics and had higher antioxidant activity than peeled rice. Parboiled rice, in which technological processing helps to maintain active substances inside the grains, exhibited also relatively high phenolic levels. The highest antimutagenic effect was proved in Indian Rice, Arborio, Jasmine Rice and Three Colours Rice independently of rice extract concentration. Because of relatively high values of phenolics and high antioxidant activity, the antimutagenic activity of the...

A multivariate analysis approach to the study of chemical and functional properties of chemo‐diverse plant derivatives: lavender essential oils

ABSTRACTSix lavender essential oils, L. angustifolia and five Lavandula x hybrida cultivars (Super Z, Abrialis, R.C., Alardii and Ordinario), were evaluated from a phytochemical and biological standpoint, and the results were computed by using multivariate data analysis. The essential oils were analysed by gas chromatography, gas chromatography–mass spectrometry and headspace gas‐chromatography. Multivariate analyses (principal component analysis) identified three main phytochemical clusters among lavender essential oils, represented by 1,8‐cineole, linalyl acetate and linalool. Functional properties of the essential oils were checked by (1) estimating cytotoxicity and genotoxicity using the Saccharomyces cerevisiae D7 strain; (2) determining antifungal activity against three common phytopathogens (Pythium ultimum, Magnaporthe grisea and Botrytis cinerea), by performing an agar vapour bioassay; and (3) calculating the antioxidant capacity by using the 1,1‐diphenyl‐2‐picrylhydrazyl (DPPH) and β‐carotene bleaching tests. No mutagenic effects were detected, but multivariate analyses (PLS, partial least squares regression) showed that the essential oils belonging to the linalool cluster were the most cytotoxic. Antifungal activity against phytopathogens confirmed the predictive results of PLS. The differences among lavender essential oils regarding weak antioxidant capacity showed a positive relationship between the high polarity compounds and the DPPH method, as determined by PLS. The opposite effect was shown for the same type of compound and β‐carotene. Ketones and esters did not exert any significant antioxidant activity. In conclusion, taking lavender essential oils as a model and computing multivariate data of a reduced number of parameters, the proposed approach assured the description of the relationship between a phytocomplex, its constituents and bioactivities, and allowed a comprehensive, predictive approach to be defined, for which the chemical profile provides a possible synergic overall effort in terms of applicative perspectives. Copyright © 2013 John Wiley & Sons, Ltd.

Cell inactivation studies on yeast cells under euoxic and hypoxic condition using electron beam from microtron accelerator

In the case of sparsely ionizing radiation such as electron, the dose rate and the pattern of energy deposition of the radiation are the important physical factors which can affect the amount of damage in living cells. In the present study, the differences in the cell survival efficiency and dose rate effect in diploid yeast strains Saccharomyces cerevisiae X2180 and Saccharomyces cerevisiae D7 under euoxic and hypoxic condition have been quantified. Irradiation was carried out using 8 MeV pulsed electron beam from Microtron accelerator. The dose per pulse and pulse width of the beam used was 0.6 Gy and 2.3 μs, respectively, which correspond to an instantaneous dose rate of 2.6 × 105 Gy s−1. For survival studies doses were delivered at a rate of 50 pulses per second (an average dose rate of 1,800 Gy s−1). Fricke and alanine dosimeters were used to measure the dose delivered to the sample. A significant difference in the dose response has been observed under euoxic and hypoxic condition. Dose rate effect has been studied by changing the pulse repetition rate of the Microtron and the dose rate used was from 180 to 1800 Gy min−1. A significant dose rate effect was observed under euoxic condition for Saccharomyces cerevisiae X2180 but the same was absent under hypoxic condition. The dose rate effect was absent for Saccharomyces cerevisiae D7 under both irradiation condition. The survival curves are found to be sigmoidal in shape under both condition but with a wider shoulder under hypoxic condition. The D0 value and the Oxygen Enhancement Ratio (OER) at that point have been derived.

Chemical fingerprinting and bioactivity of Amazonian Ecuador Croton lechleri Müll. Arg. (Euphorbiaceae) stem bark essential oil: A new functional food ingredient?

Croton lechleri essential oil has been obtained by steam distillation of fresh stem bark from Amazonian Ecuador adult plants (yield: 0.61ml/kg [0.061%]; density: 1.01g/ml), and then chemically characterised by GC (Gas Chromatography) and GC–MS (gas chromatography–mass spectrometry). Seventy-four chemicals were detected and identified; the most abundant in descending order, were the sesquiterpenes sesquicineole (17.29%), α-calacorene (11.29%), 1,10-di-epi-cubenol (4.75%), β-calacorene (4.34%) and epi-cedrol (4.09%). Monoterpenes checked with a relative peak area higher than 2.0% were α-pinene (2.01%), p-cymene (2.61%), limonene (4.20%) and borneol (2.67%). The structure of the main chemicals were confirmed by GC–MS and 1H NMR analyses. Spectrophotometric 1,1-diphenyl-2-picrylhydrazyl (DPPH) and DPPH-(high performance) thin layer chromatography (DPPH-(HP)TLC) bioautographic assays showed a lower radical scavenging capacity (IC50) with respect to commercial thyme essential oil and BHA (butylated hydroxyl anisole), pointing out, however, that the C. lechleri essential oil fraction, characterised by α-calacorene, β-calacorene and δ-cadalene, was the most involved in the bioactivity. Similar results were obtained with β-carotene bleaching assay, where the IC50 values were 0.291±0.024mg/ml for C. lechleri essential oil, 0.164±0.013 and 1.34×10−4±10−5mg/ml for thyme essential oil and BHA, respectively. (HP)TLC-bioautographic assay performed with Gram positive and Gram negative bacteria revealed a minimum inhibitory concentration (MIC) values comprised between 0.10mg/ml (Escherichia coli) and 10.10mg/ml (for e.g. Pseudomonas aeruginosa), and the fraction mainly characterised by sesquicineole (97.38%) as the most involved in antibacterial capacity. Ames test employing Salmonella typhimurium TA98 and TA100 with and without a metabolic activation mixture (S9 mix) demonstrated the absence of mutagenicity of the C. lechleri essential oil between a concentration range of 10−2 and 100mg/plate. The same results were achieved by Saccharomyces cerevisiae D7 strain assay. An interesting mutagen-protective efficacy was evidenced by a 30% and 33% revertants reduction of TA98 strain treated with 2-aminoanthracene and nitrofluorene (2μg/plate), suggesting, above all, the possibility to employ C. lechleri essential oil as a new flavouring protective ingredient for foods or dietary supplements against potential mutagens formed during cooking and/or processing in general.

Genotoxicity of 4-nonylphenol and nonylphenol ethoxylate mixtures by the use of Saccharomyces cerevisiae D7 mutation assay and use of this text to evaluate the efficiency of biodegradation treatments

Nonylphenol ethoxylates (NPnEOs, where n is the number of ethoxylic units in the molecule) are non-ionic surfactants widely used for domestic and industrial purposes. 4-Nonylphenol (4-NP), the main product of NPnEO biodegradation, is a toxic xenobiotic compound classified as endocrine disrupter. While numerous studies reported the toxicity and oestrogenic activity of nonylphenols, little is known about the mutagenicity of these compounds. In this paper, the genotoxicity of 4-NP and NPnEO mixtures was evaluated by using the D7 strain of Saccharomyces cerevisiae as experimental model. The same genotoxicity tests were applied to effluents deriving from experimental packed-bed bioreactors, developed for the treatment of NPnEO contaminated wastewater, in order to evaluate the residual genotoxic potential with respect to the influent waste. The target compounds fed to the bioreactors were 4-NP and NPnEO mixtures possessing an average of 5 or 1.5 ethoxylic units (Igepal CO-520 and Igepal CO-210, respectively). The results showed that 4-NP induced significant cytotoxic effect on S. cerevisiae cells at 50mg/L, as well as mutagenic effects at the lowest tested concentrations (12 and 25mg/L). 4-NP was the most genotoxic compound among those assayed, followed by Igepal CO-210, whereas Igepal CO-520 did not induce genotoxicity at any of the assayed concentrations. The genotoxic effects of 4-NP on yeast cells disappeared after the treatment of 4-NP artificially contaminated water in the bioreactor. This indicates that the biological treatment is capable of removing not only the pollutant, but also the toxicity associated to the compound and its degradation metabolites. This study represents, to the best of our knowledge, the first report that evaluates the genotoxicity of both 4-NP, NPnEOs and their potential aerobic degradation products on an eukaryotic organism. The obtained results suggest that the S. cerevisiae D7 strain is a very effective model microorganism to study the induction of genotoxic damage by the compounds under study. Moreover, this yeast assay has been proved effective to evaluate the detoxification effect deriving from biotreatment processes.

Effect of 905 MHz microwave radiation on colony growth of the yeast Saccharomyces cerevisiae strains FF18733, FF1481 and D7

BackgroundThe aim of this study was to evaluate the effect of weak radiofrequency microwave (RF/MW) radiation emitted by mobile phones on colony growth of the yeast Saccharomyces cerevisiae.Materials and methodsS. cerevisiae strains FF18733 (wild-type), FF1481 (rad1 mutant) and D7 (commonly used to detect reciprocal and nonreciprocal mitotic recombinations) were exposed to a 905 MHz electromagnetic field that closely matched the Global System for Mobile Communication (GSM) pulse modulation signals for mobile phones at a specific absorption rate (SAR) of 0.12 W/kg.ResultsFollowing 15-, 30- and 60-minutes exposure to RF/MW radiation, strain FF18733 did not show statistically significant changes in colony growth compared to the control sample. The irradiated strains FF1481 and D7 demonstrated statistically significant reduction of colony growth compared to non-irradiated strains after all exposure times. Furthermore, strain FF1481 was more sensitive to RF/MW radiation than strain D7.ConclusionsThe findings indicate that pulsed RF/MW radiation at a low SAR level can affect the rate of colony growth of different S. cerevisiae strains.

Ecuadorian stingless bee (Meliponinae) honey: A chemical and functional profile of an ancient health product

Stingless bee honey samples from west Amazonian Ecuador were studied for their physiochemical, chemical and functional properties. Reducing sugars (44.9 ± 5.72 g/100 g), water (34.1 ± 4.34 g/100 g), free acidity (31.8 ± 4.05 meq/100 g), diastase activity (1.60 ± 0.20 u.d./g), hydroxymethylfurfural (15.0 ± 1.91 mg/kg), electrical conductivity (0.48 ± 0.06 mS/cm), ash (0.28 ± 0.04 g/100 g), colour (150 mm Pfund) were determined as physicochemical parameters. Melissopalynological analyses were processed evidencing pollen belonging to 14 plant families. Glucose (25.5 ± 3.41 g/100 g), fructose (25.2 ± 3.37 g/100 g) and sucrose (3.72 ± 0.49 g/100 g) contents were determined by HPLC, evidencing equal concentrations between fructose and glucose. Coumarins and flavonoids were determined by densitometric HPTLC: fraxin and bergamotin (0.065 ± 0.009; 0.035 ± 0.005 μg/g) among coumarins; luteolin (0.045 ± 0.006 μg/g), quercitrin (0.020 ± 0.003 μg/g), isoramnetin (0.015 ± 0.002 μg/g) among flavonoids. Among the vitamin E isomers, evaluated by HPLC, the occurrence of the only β-tocopherol (1.12 ± 0.15 μg/g) was noted. All these results were compared with those acquired for two multifloral Apis mellifera honeys. DPPH and β-carotene bleaching tests were performed, showing interesting values for Ecuadorian honey samples, higher than those shown by multifloral A. mellifera honeys (88.1 ± 11.1 DPPH inhibition%; 70.8 ± 8.90 β-carotene inhibition%). Antibacterial activity, against both Gram positive and Gram negative bacteria, revealed MIC values (10–50 μg/ml) always lower than those of A. mellifera honeys. Ecuadorian Meliponinae honey samples also showed anti-mutagenic activity assayed with Saccharomyces cerevisiae D7 strain, inhibiting back mutation over the entire range of concentrations.

Genotoxicity of leachates from highly polluted lowland river sediments destined for disposal in landfill

The Matanza-Riachuelo is one of the most polluted rivers of Latin America. The complex chemical mixture of pollutants discharged into the river is accumulated in the river sediments. In this paper, Matanza-Riachuelo river sediment composition and genotoxicity were tested in order to develop a cost-effective, environmentally sound option for disposal and management of contaminated dredged materials. Sampling was performed in a rural area, in a solid waste dumpsite and also in an urban and industrial area. The concentrations of total heavy metals increased from the upper basin to the lower basin. The Ames Salmonella typhimurium test and the Saccharomyces cerevisiae D7 test were performed using toxicity characteristic leachate procedure (TCLP) leachates. The concentrations of copper, lead, and chromium in the leachates exceeded the guide levels for the protection of aquatic life. Low concentrations of organic chlorinated compounds were detected in the leachates. Genotoxic profiles were obtained by testing TCLP leachates from polluted sediment samples with Salmonella typhimurium, Saccharomyces cerevisiae D7, and water sediment suspension with Allium cepa test. No mutagenicity effects on Ames test were observed. Gene conversion and mitotic reversion in Saccharomyces cerevisiae D7 and chromosome aberration in Allium cepa were induced by the sediment samples. Results obtained suggest that dredged sediments could be classified as genotoxic hazardous waste.

Evaluation of Genotoxicity and Toxicity of Buenos Aires City Hospital Wastewater Samples

The untrated wastewaters from health centers present a potential risk aquatic ecosystems because of the content of toxic and genotoxic chemicals. The composition of these wastewaters discharged to the urban sewer system present fluctuations generated by spatial and temporal variations in the discharges of citostatics, heavy metals (Pb, Cr, Hg), antibiotics, etc. In Buenos Aires city the Hospital effluents are discharged to the sewer system with no previous treatment, in turn, the wastes of the municipal sewage system are released to the Río de la Plata, with no treatment at all. This river is also the source of water for the plants that provide drinking water to the city. The objective of this paper was the study of the genotoxicity and toxicity from Hospital San Martín wastewaters. This General Hospital releases approximately 560 m3/daily of effluents to the municipal sewer system, from. Sampling this effluent was performed seasonally, in this paper we report the results obtained in summer 2003, autumn 2004 samples. The determination of toxicity was performed with the Pseudomonas fluorescens growth inhibition test and with the determination of mitotic index in Allium root tips. On the other hand, the genotoxicity was studied with Saccharomyces cerevisiae D7 assay and with the induction of chromosomal aberrations in Allium cepa test. Each sample was assayed either after sterilization by filtration or as an XAD-2 resins extract. The summer 2003 samples were toxic and genotoxic in the Allium test when were assayed at 100% and 50% v/v dilutions, genotoxicity in the Saccharomyces cerevisiae test was also detected at 100% and 10% v/v dilutions. The samples of autumn 2004 were not genotoxic, only toxicity for Saccaromyces strain was detected when raw effluents and 100X extracts were tested. None of the wastewaters samples assayed demonstrated toxicity in the Pseudomonas fluorescens test.

Evaluation of Genotoxicity and Toxicity of Buenos Aires City Hospital Wastewater Samples

The untrated wastewaters from health centers present a potential risk aquatic ecosystems because of the content of toxic and genotoxic chemicals. The composition of these wastewaters discharged to the urban sewer system present fluctuations generated by spatial and temporal variations in the discharges of citostatics, heavy metals (Pb, Cr, Hg), antibiotics, etc. In Buenos Aires city the Hospital effluents are discharged to the sewer system with no previous treatment, in turn, the wastes of the municipal sewage system are released to the Río de la Plata, with no treatment at all. This river is also the source of water for the plants that provide drinking water to the city. The objective of this paper was the study of the genotoxicity and toxicity from Hospital San Martín wastewaters. This General Hospital releases approximately 560 m3/daily of effluents to the municipal sewer system, from. Sampling this effluent was performed seasonally, in this paper we report the results obtained in summer 2003, autumn 2004 samples. The determination of toxicity was performed with the Pseudomonas fluorescens growth inhibition test and with the determination of mitotic index in Allium root tips. On the other hand, the genotoxicity was studied with Saccharomyces cerevisiae D7 assay and with the induction of chromosomal aberrations in Allium cepa test. Each sample was assayed either after sterilization by filtration or as an XAD-2 resins extract. The summer 2003 samples were toxic and genotoxic in the Allium test when were assayed at 100% and 50% v/v dilutions, genotoxicity in the Saccharomyces cerevisiae test was also detected at 100% and 10% v/v dilutions. The samples of autumn 2004 were not genotoxic, only toxicity for Saccaromyces strain was detected when raw effluents and 100X extracts were tested. None of the wastewaters samples assayed demonstrated toxicity in the Pseudomonas fluorescens test.

Evaluation of Genotoxicity and Toxicity of Buenos Aires City Hospital Wastewater Samples

The untrated wastewaters from health centers present a potential risk aquatic ecosystems because of the content of toxic and genotoxic chemicals. The composition of these wastewaters discharged to the urban sewer system present fluctuations generated by spatial and temporal variations in the discharges of citostatics, heavy metals (Pb, Cr, Hg), antibiotics, etc. In Buenos Aires city the Hospital effluents are discharged to the sewer system with no previous treatment, in turn, the wastes of the municipal sewage system are released to the Río de la Plata, with no treatment at all. This river is also the source of water for the plants that provide drinking water to the city. The objective of this paper was the study of the genotoxicity and toxicity from Hospital San Martín wastewaters. This General Hospital releases approximately 560 m3/daily of effluents to the municipal sewer system, from. Sampling this effluent was performed seasonally, in this paper we report the results obtained in summer 2003, autumn 2004 samples. The determination of toxicity was performed with the Pseudomonas fluorescens growth inhibition test and with the determination of mitotic index in Allium root tips. On the other hand, the genotoxicity was studied with Saccharomyces cerevisiae D7 assay and with the induction of chromosomal aberrations in Allium cepa test. Each sample was assayed either after sterilization by filtration or as an XAD-2 resins extract. The summer 2003 samples were toxic and genotoxic in the Allium test when were assayed at 100% and 50% v/v dilutions, genotoxicity in the Saccharomyces cerevisiae test was also detected at 100% and 10% v/v dilutions. The samples of autumn 2004 were not genotoxic, only toxicity for Saccaromyces strain was detected when raw effluents and 100X extracts were tested. None of the wastewaters samples assayed demonstrated toxicity in the Pseudomonas fluorescens test.

Antigenotoxic potential of glucomannan on four model test systems

Antimutagenic, anticlastogenic, and bioprotective effect of polysaccharide glucomannan (GM) isolated from Candida utilis was evaluated in four model test systems. The antimutagenic effect of GM against 9-aminoacridine (9-AA)- and sodium azide (NaN3)-induced mutagenicity was revealed in the Salmonella typhimurium strains TA97 and TA100, respectively. GM showed anticlastogenic effect against N-nitroso-N'-methylurea (NMU) induced chromosome aberrations in the Vicia sativa assay. The bioprotective effect of GM co-treated with methyl-methane-sulphonate (MMS) was also established in Chlamydomonas reinhardtii repair deficient strains uvs10 and uvs14. The statistically significant antimutagenic potential of GM was not proved against 4-nitro-quinoline-1-oxide (4-NQO)-induced mutagenicity in Saccharomyces cerevisiae D7 assay. It may be due to bioprotectivity of alpha-mannan and beta-glucan, which are integral part of S. cerevisiae cell walls. Due to the good water solubility, low molecular weight (30 kDa), antimutagenic/anticlastogenic, and bioprotective activity against chemical compounds differing in mode of action, GM appears to be a promising natural protective (antimutagenic) agent.

Sodium hypochlorite-, chlorine dioxide- and peracetic acid-induced genotoxicity detected by the Comet assay and Saccharomyces cerevisiae D7 tests.

Mutagenicity of drinking water is due not only to industrial, agricultural and urban pollution but also to chlorine disinfection by-products. Furthermore, residual disinfection is used to provide a partial safeguard against low level contamination and bacterial re-growth within the distribution system. The aims of this study were to further evaluate the genotoxic potential of the world wide used disinfectants sodium hypochlorite and chlorine dioxide in human leukocytes by the Comet assay and in Saccharomyces cerevisiae strain D7 (mitotic gene conversion, point mutation and mitochondrial DNA mutability, with and without endogenous metabolic activation) and to compare their effects with those of peracetic acid, proposed as an alternative disinfectant. All three disinfectants are weakly genotoxic in human leukocytes (lowest effective dose 0.2 p.p.m. for chlorine dioxide, 0.5 p.p.m. for sodium hypochlorite and peracetic acid). The results in S.cerevisiae show a genotoxic response on the end-points considered with an effect only at doses higher (5- to 10-fold) than the concentration normally used for water disinfection; sodium hypochlorite and peracetic acid are able to induce genotoxic effects without endogenous metabolic activation (in stationary phase cells) whereas chlorine dioxide is effective in growing cells. The Comet assay was more sensitive than the yeast tests, with effective doses in the range normally used for water disinfection processes. The biological effectiveness of the three disinfectants on S.cerevisiae proved to be strictly dependent on cell-specific physiological/biochemical conditions. All the compounds appear to act on the DNA and peracetic acid shows effectiveness similar to sodium hypochlorite and chlorine dioxide.

Cytotoxic and genotoxic effects of megazol, an anti-Chagas’ disease drug, assessed by different short-term tests

Cyto- and genotoxicity induced by drugs can limit the dose and duration of treatment, can adversely affect patient quality of life, and may be life-threatening. Two drugs are currently being used for treatment of the acute phase of Chagas’ disease and both have serious undesirable effects. In this research, cyto- and genotoxic activity of the nitroimidazole-tiadiazole derivative CL 64855 2-amino-5-(1-methyl-5-nitro-2-imidazolyl)-1,3,4-thiadiazole (megazol), a promising alternative drug, was evaluated in vitro with different short-term tests: (a) induction of recombination events and mutation in the yeast Saccharomyces cerevisiae D7 strain, with and without induction of cytochrome P-450; DNA damage (single and double strand breaks, alkali-labile sites, etc.) by the Comet assay in different mammalian cells. S. cerevisiae did not show a significant increase of mutant and recombinant event frequency, both with and without cytochrome P-450. On the other hand, the cytochrome complex appeared to detoxify the drug with respect to cytotoxicity. Results in rat and mouse fresh leukocytes showed a dose–response relation of drug-induced DNA damage. Findings in treated VERO cells suggested a complex treatment time–DNA damage relationship and the possible induction of repair mechanisms. Furthermore, bleomycin effects were increased in rat cells by simultaneous administration of megazol. Megazol shows different biological activity in relation to cellular types and experimental conditions (with or without cytochrome P-450, short/long time of exposure, with or without other genotoxins), thus suggesting a modulation of effectiveness by different physiological/biochemical conditions of cells. The findings could be useful to evaluate new megazol-derived compounds and to assess the risks/benefits relationship for each drug.

Urban airborne particulate: genotoxicity evaluation of different size fractions by mutagenesis tests on microorganisms and comet assay

The genotoxic effects of different size fractions of airborne particulate (Total, PM 10 and PM 2.5), extracted with acetone or toluene, were evaluated by: the Ames plate test (TA98 and TA100 strains, w/o S9), gene conversion and reversion (w/o endogenous metabolic activation) in the Saccharomyces cerevisiae D7 strain, and the comet assay on human leukocytes. The data on human leukocytes confirm the sensitivity of the comet assay and its applicability to assess genotoxicity in environmental samples. The PM 2.5 fraction of airborne particulate generally shows the highest concentration of DNA-damaging compounds. Genotoxic response, in all the test systems applied, is highly dependent on extraction solvent used. Acetone seems to extract compounds with more similar genotoxic responses in the three test systems used than toluene extracts. Toluene appears to extract air pollutants genotoxic on yeast and leukocytes but is mainly cytotoxic on Salmonella.