Mutagenicity of carcinogenic azo dyes and their derivatives

Ames test study designs for nitrosamine mutagenicity testing: qualitative and quantitative analysis of key assay parameters

The robust control of genotoxic N-nitrosamine (NA) impurities is an important safety consideration for the pharmaceutical industry, especially considering recent drug product withdrawals. NAs belong to the 'cohort of concern' list of genotoxic impurities (ICH M7) because of the mutagenic and carcinogenic potency of this chemical class. In addition, regulatory concerns exist regarding the capacity of the Ames test to predict the carcinogenic potential of NAs because of historically discordant results. The reasons postulated to explain these discordant data generally point to aspects of Ames test study design. These include vehicle solvent choice, liver S9 species, bacterial strain, compound concentration, and use of pre-incubation versus plate incorporation methods. Many of these concerns have their roots in historical data generated prior to the harmonization of Ames test guidelines. Therefore, we investigated various Ames test assay parameters and used qualitative analysis and quantitative benchmark dose modelling to identify which combinations provided the most sensitive conditions in terms of mutagenic potency. Two alkyl-nitrosamines, N-nitrosodimethylamine (NDMA) and N-nitrosodiethylamine (NDEA) were studied. NDMA and NDEA mutagenicity was readily detected in the Ames test and key assay parameters were identified that contributed to assay sensitivity rankings. The pre-incubation method (30-min incubation), appropriate vehicle (water or methanol), and hamster-induced liver S9, alongside Salmonella typhimurium strains TA100 and TA1535 and Escherichia coli strain WP2uvrA(pKM101) provide the most sensitive combination of assay parameters in terms of NDMA and NDEA mutagenic potency in the Ames test. Using these parameters and further quantitative benchmark dose modelling, we show that N-nitrosomethylethylamine (NMEA) is positive in Ames test and therefore should no longer be considered a historically discordant NA. The results presented herein define a sensitive Ames test design that can be deployed for the assessment of NAs to support robust impurity qualifications.

Mutagenicity Assessment of Homologous Series of Methyl Ester Sulphonates (MES) Using the Bacterial Reverse Mutation (Ames) Test

Methyl ester sulphonate (MES) is an anionic surfactant that is suitable to be used as an active ingredient in household products. Four palm-based MES compounds with various carbon chains, namely C12, C14, C16 and C16/18 MES, were assayed by the in vitro bacterial reverse mutation (Ames) test in the Salmonella typhimurium strains TA98, TA100, TA1535, and TA1537 and the Escherichia coli strain WP2 uvrA, with the aim of establishing the safety data of the compounds, specifically their mutagenicity. The test was also carried out on linear alkylbenzene sulphonate (LAS) for comparison. The plate incorporation method was conducted according to the Organization for Economic Cooperation and Development (OECD) Test Guideline 471. All compounds were tested at five analysable non-cytotoxic concentrations, varying from .001 mg/plate to 5 mg/plate, with and without S-9 metabolic activation. All tested concentrations showed no significant increase in the number of revertant colonies compared to revertant colonies of the negative control. The Ames test indicated that each concentration of C12, C14, C16, C16/18 MES, and LAS used in this study induced neither base-pair substitutions nor frame-shift mutations in the S. typhimurium strains TA98, TA100, TA1535, and TA1537 and the E. coli strain WP2 uvrA. The results showed that C12, C14, C16 and C16/18 MES have no potential mutagenic properties in the presence and absence of S-9 metabolic activation, similarly to LAS. Therefore, the MES is safe to be used as an alternative to petroleum-based surfactants for household cleaning products.

The global anaerobic metabolism regulator fnr is necessary for the degradation of food dyes and drugs by Escherichia coli

IMPORTANCE

This work has broad relevance due to the ubiquity of dyes containing azo bonds in food and drugs. We report that azo dyes can be degraded by human gut bacteria through both enzymatic and nonenzymatic mechanisms, even from a single gut bacterial species. Furthermore, we revealed that environmental factors, oxygen, and L-Cysteine control the ability of E. coli to degrade azo dyes due to their impacts on bacterial transcription and metabolism. These results open up new opportunities to manipulate the azoreductase activity of the gut microbiome through the manipulation of host diet, suggest that azoreductase potential may be altered in patients suffering from gastrointestinal disease, and highlight the importance of studying bacterial enzymes for drug metabolism in their natural cellular and ecological context.

Adsorption profile of anionic and cationic dyes through Fe3O4 embedded oxidized Sterculia gum/Gelatin hybrid gel matrix

Hazardous effluents from textile industries being major contributors of water pollution and impose potential adverse effects on environment. In present study, Fe₃O₄ embedded oxidized Sterculia gum/Gelatin hybrid matrix have been fabricated and evaluated for enrichment of methyl orange (MO) and methylene blue (MB). Newly synthesized matrix was characterized through powdered XRD, FTIR, FESEM, TEM and TGA. Integrated nanoparticles improved dye enrichment and facilitated removal of matrix from the aqueous solution under the influence of magnetic field. Influence of various reaction parameters viz.: contact time, adsorbent dose, initial dye concentration, temperature & pH of the adsorption medium on dye enrichment have been evaluated. Maximum adsorption (90 % and 88 % for MO and MB respectively) has been achieved. Langmuir, Freundlich and Tempkin adsorption isotherms have been evaluated. Experimental results validate well fitted Freundlich isotherm for MO and Temkin isotherm for MB. Adsorption kinetics has been analyzed through Pseudo first order, second order kinetic and intra particle diffusion models. Adsorption of both dyes was best explained via pseudo second order kinetic model. Negative value of Gibb's free energy change (-26.487 KJ mol ^-1 and - 24.262 KJ mol ^-1) for MB and MO at 303 K was an indication of spontaneity of the reaction.

Recent Advances in Functional Polymer Materials for Energy, Water, and Biomedical Applications: A Review

Academic research regarding polymeric materials has been of great interest. Likewise, polymer industries are considered as the most familiar petrochemical industries. Despite the valuable and continuous advancements in various polymeric material technologies over the last century, many varieties and advances related to the field of polymer science and engineering still promise a great potential for exciting new applications. Research, development, and industrial support have been the key factors behind the great progress in the field of polymer applications. This work provides insight into the recent energy applications of polymers, including energy storage and production. The study of polymeric materials in the field of enhanced oil recovery and water treatment technologies will be presented and evaluated. In addition, in this review, we wish to emphasize the great importance of various functional polymers as effective adsorbents of organic pollutants from industrial wastewater. Furthermore, recent advances in biomedical applications are reviewed and discussed.

A review on application of phytoremediation technique for eradication of synthetic dyes by using ornamental plants

Phytoremediation emerges as an innovative and eco-friendly technique to remediate textile dyes with the use of various categories of plants. In recent years, ornamental plants emerge as more attractive and effective substitute in comparison to edible plants for phytoremediation. Regardless of aesthetic value, some ornamental plants can be grown to remediate the sites contaminated with dyes, heavy metals, pesticides, or other organic compounds. In this review, we focus on pioneer research on synthetic dye removal using ornamental plants and evaluate the phytoremediation capability of ornamental plants for treatment of textile effluent. This paper also emphasized specific ornamental plants having high accumulation and tolerance ability for removal of dyes. The mechanisms explored for the phytoremediation of dyes by ornamental plants have also been explained. This review will also be helpful for researchers for exploring more new ornamental plants in phytoremediation technique.

Photoinduced degradation of indigo carmine: insights from a computational investigation

In this work, we present a computational investigation on the photoexcitation of indigo carmine (IC). Physical insights regarding IC photoexcitation and photolysis were obtained from a fundamental perspective through quantum chemistry computations. Density functional theory (DFT) was used to investigate the ground state while its time-dependent formalism (TD-DFT) was used for probing excited state properties, such as vertical excitation energies, generalized oscillator strengths (GOS), and structures. All the computations were undertaken using two different approaches: M06-2X/6-311+G(d,p) and CAM-B3LYP/6-311+G(d,p), in water. Results determined using both methods are in systematic agreement. For instance, the first singlet excited state was found at 2.28 eV (with GOS = 0.4730) and 2.19 eV (GOS = 0.4695) at the TD-DFT/CAM-B3LYP/6-311+G(d,p) and TD-DFT/M06-2X/6-311+G(d,p) levels of theory, respectively. Excellent agreement was observed between the computed and the corresponding experimental UV-Vis spectra. Moreover, results suggest IC undergoes photodecomposition through excited state chemical reaction rather than via a direct photolysis path. To the best of our knowledge, this work is the first to tackle the photoexcitation, and its potential connections to photodegradation, of IC from a fundamental chemical perspective, being presented with expectations to motivate further studies.

Highly Luminescent Copper Nanoclusters Stabilized by Ascorbic Acid for the Quantitative Detection of 4-Aminoazobenzene

As one of the widely studied metal nanoclusters, the preparation of copper nanoclusters (Cu NCs) by a facile method with high fluorescence performance has been the interest of researchers. In this paper, a simple, green, clean, and time-saving chemical etching method was used to synthesize water-soluble Cu NCs using ascorbic acid (AA) as the reducing agent. The as-prepared Cu NCs showed strong green fluorescence (with a quantum yield as high as 33.6%) and high ion stability, and good antioxidant activity as well. The resultant Cu NCs were used for the detection of 4-aminoazobenzene (one of 24 kinds of prohibited textile compounds) in water with a minimum detection limit of 1.44 μM, which has good potential for fabric safety monitoring.

Photolysis of Indigo Carmine solution by planar vacuum-ultraviolet (147 nm) light source

Advanced oxidation processes (AOPs) are an attractive method to decompose dye-containing wastewaters, because they avoid issues of secondary pollution. In particular, a vacuum-ultraviolet (VUV) process is the simplest method, because an oxidation accelerator or a catalyst is not required. Conventional VUV sources with wavelengths of 185 nm or 172 nm have been used. We predicted that a shorter wavelength VUV process would have a higher ability to decompose dyes in wastewater. We developed a new planar light source that could emit a resonance line at 147 nm and a broad molecular line at 172 nm. The irradiance was 8.7 mW/cm² at a distance of 20 mm from the emission surface to the UV power meter. We then conducted photocatalytic experiments of an Indigo Carmine solution at 3.33 × 10^-4 mol/L to confirm the decomposition abilities of the developed light source, an excimer lamp of 172 nm and a Hg lamp of 254 nm. From the HPLC results, changes in Indigo Carmine concentration with the developed light source were equivalent to those with the excimer lamp. However, the residual ratio of total organic carbon (TOC) with the developed light source was lower than those with the other lamps. Therefore, a wavelength of 147 nm is superior to the conventional wavelength of 172 nm for Indigo Carmine decomposition. In addition, the developed light source emits VUV from only one side, which is a flat emitting surface. Consequently, the developed light source would have reduced manufacturing and maintenance costs compared to current VUV processing equipment.

Application and stability of cathodes with manganese dioxide nanoflowers supported on Vulcan by Fenton systems for the degradation of RB5 azo dye

This work describes the electrochemical degradation of Reactive Black 5 (RB5) by two methods: electrochemical and photo-assisted electrochemical degradation with and without a Fenton reagent. Two anodes were used, Pt and boron-doped diamond (BDD, 2500 ppm), and the cathode was 3% MnO₂ nanoflowers (NFMnO₂) on a carbon gas diffusion electrode (GDE). An electrochemical cell without a divider with a GDE with 3% w/w NFMnO₂/C supported on carbon Vulcan XC72 was used. The decolorization efficiency was monitored by UV-vis spectroscopy, and the degradation was monitored by Total Organic Carbon (TOC) analysis. For dissolution monitoring, aliquots (1 mL) were collected during the degradation. After 6 h of H₂O₂ electrogeneration, the manganese concentration in the RB5 solution was only 23.1 ± 1.2 μg L^-1. It was estimated that approximately 60 μg L^-1 (<0.2%) of manganese migrated from the GDE to the solution after 12 h of electrolysis, which indicated the good stability of the GDE. The photoelectro-Fenton-BDD (PEF-BDD) processes showed both the best color removal percentage (∼93%) and 91% of mineralization. The 3% NFMnO₂/C GDE is promising for RB5 degradation.

Influence of auxochrome group in disperse dyes bearing azo groups as chromophore center in the biotransformation and molecular docking prediction by reductase enzyme: Implications and assessment for environmental toxicity of xenobiotics

Synthetic azo dyes have increasingly become a matter of great concern as a result of the genotoxic and mutagenic potential of the products derived from azo dye biotransformation. This work evaluates the manner in which reducing enzymes produced by Escherichia coli (E. coli) act on three disperse dyes bearing azo groups, namely Disperse Red 73 (DR 73), Disperse Red 78 (DR 78), and Disperse Red 167 (DR 167). UV-Vis spectrophotometry, high-performance liquid chromatography with diode array detector (HPLC-DAD), and liquid chromatography mass spectrometry (LC-MS/MS) were applied towards the identification of the main products. Seven days of incubation of the azo dyes with the tested enzymes yielded a completely bleached solution. 3-4-Aminophenyl-ethyl-amino-propanitrile was detected following the biotransformation of both DR 73 and DR 78. 4-Nitroaniline and 2-chloro-4-nitroaniline were detected upon the biotransformation of DR 73 and DR 78, respectively. The main products derived from the biotransformation of DR 167 were dimethyl 3,3'-3-acetamido-4-aminophenyl-azanedyl-dipropanoate and 2-chloro-4-nitroaniline. The results imply that DR 73 lost the CN^- substituent during the biotransformation. Furthermore, theoretical calculations were also carried out aiming at evaluating the interaction and reactivity of these compounds with DNA. Taken together, the results indicate that DR 73, DR 78, and DR 167 pose health risks and serious threats to both human beings and the environment at large as their biotransformation produces harmful compounds such as amines, which have been widely condemned by the International Agency for Research on Cancer.

Natural Predominance of Abscisic Acid in Pongammia pinnata ("Karanj") Honey Contributed to its Strong Antimutagenicity

Various samples of raw (unprocessed) floral honey collected from different geographical locations of India were assayed for its antimutagenicity against ethyl methanesulfonate in E. coli MG1655 cells through rifampicin resistance assay. A monofloral honey ("Pongammia pinnata", local name "Karanj") displayed maximum antimutagenicity (78.0 ± 1.7; P ≤ 0.05). Solid phase extraction (using Amberlite XAD-2 resin) followed by HPLC resulted into different peaks displaying varying antimutagenicity. Peak at retention time (R_t) 27.9 min (henceforth called P₂₈) displayed maximum antimutagenicity and was further characterized to be abscisic acid (ABA) using ESI-MS and NMR. Its antimutagenicity was reconfirmed through human lymphoblast cell line (TK6) mutation assay using thymidine kinase (tk^+/-) cell line. Although ABA from this honey displayed strong antimutagenicity, it lacked any in vitro antioxidant capacity indicating noninvolvement of any radical scavenging in the observed antimutagenicity.

Regenerative nanobots based on magnetic layered double hydroxide for azo dye removal and degradation

Azo dye removal and degradation protocol using magnetic LDH-based regenerative nanobots.

Rapid degradation of azo-dye using Mn–Al powders produced by ball-milling

This study was conducted on the reduction reaction of the azo dye Reactive Black 5 by means of the Mn₈₅Al₁₅ particles prepared by melt-spinning and ball-milling processes.

Preparation of a Fe3O4-Au-GO nanocomposite for simultaneous treatment of oil/water separation and dye decomposition

A nanocomposite capable of simultaneously controlling multiple water pollutants (soluble organic dye and insoluble chemical solvent) has been obtained. The Au and Fe₃O₄ nanoparticles (NPs) were modified on a graphene oxide (GO) surface via light reduction and covalent attachment. The obtained Fe₃O₄-Au-GO nanocomposite has magnetic driving ability and catalytic applications. The nanocomposite can form emulsions after wrapping an insoluble and volatile organic solvent inside; moreover, the multi-layer graphene shell structure may delay volatilization of the solvent, ensuring that the oil droplets are collected efficiently and completely by the Fe₃O₄-Au-GO nanocomposite. At the same time, the Au NPs on the surface of the composite can effectively catalyze the decomposition of an organic dye in water and the recovery of the nanocomposite catalyst can also be realized using an external magnetic field. The simultaneous treatment of non-soluble oil (organic solvents) and organic dyes in water can be realized by the Fe₃O₄-Au-GO nanocomposite. Therefore, based on surface modification of GO, one material with two types of water pollution treatment functions was realized. This provides a new way for the simultaneous treatment of oil separation and dye decomposition, and the assembled structure may result in emulsions to give new applications in fuel cells and other fields.

Identification of methylglyoxal as a major mutagen in wood and bamboo pyroligneous acids

To identify the major mutagen in pyroligneous acid (PA), 10 wood and 10 bamboo pyroligneous acids were examined using the Ames test in Salmonella typhimurium strains TA100 and TA98. Subsequently, the mutagenic dicarbonyl compounds (DCs), glyoxal, methylglyoxal (MG), and diacetyl in PA were quantified using high-performance liquid chromatography, and the mutagenic contribution ratios for each DC were calculated relative to the mutagenicity of PA. Eighteen samples were positive for mutagens and showed the strongest mutagenicity in TA100 in the absence of S9 mix. MG had the highest mutagenic contribution ratio, and its presence was strongly correlated with the specific mutagenicity of PA. These data indicate that MG is the major mutagen in PA.

Metabolism and biotransformation of azo dye by bacterial consortium studied in a bioreaction calorimeter

Effluents from leather and textile industries are difficult for treatment owing to its recalcitrant nature. Since the volume of effluent generated are high, a robust and active microbial consortia is required for effective treatment. The focus in the present study is the calorimetric traceability of the metabolic behaviors of mixed microbial consortia, while it grows and degrades recalcitrant substance such as an azo dye acid blue 113. The consortium exhibited a syntrophic division of substrate and was effective in degrading dye up to 0.8g/l. Notably, it was able to degrade 93.7% of the azo dye in 12-16h whereas its monocultures required 48-72h to reach 82.1%. The products of biodegradation were analyzed and the chemical pathway substantiated using chemical thermodynamic and energy release patterns. MTT assay confirmed that emanates are eco-friendly. Heat profile pattern and bioenergetics provide fundamental data for a feasible application in commercial level.

Novel Strategy for Tracking the Microbial Degradation of Azo Dyes with Different Polarities in Living Cells

Direct visualization evidence is important for understanding the microbial degradation mechanisms. To track the microbial degradation pathways of azo dyes with different polar characterizations, sensors based on the fluorescence resonance energy transfer (FRET) from 1,8-naphthalimide to azo dyes were synthesized, in which the quenched fluorescence will recover when the azo bond was cleaved. In living cells, the sensor-tracking experiment showed that the low polarity and hydrophobic azo dye can be taken up into the cells and reduced inside the cells, whereas the high polarity and hydrophilic azo dye can be reduced only outside the cells because of the selective permeability of the cell membranes. These results indicated that there were two different bacterial degradation pathways available for different polarity azo dyes. To our knowledge, no fluorescent sensor has yet been designed for illuminating the microbial degradation mechanisms of organic pollutants with different characteristics.

Phytoremediation of textile dyes and effluents: Current scenario and future prospects

Phytoremediation has emerged as a green, passive, solar energy driven and cost effective approach for environmental cleanup when compared to physico-chemical and even other biological methods. Textile dyes and effluents are condemned as one of the worst polluters of our precious water bodies and soils. They are well known mutagenic, carcinogenic, allergic and cytotoxic agents posing threats to all life forms. Plant based treatment of textile dyes is relatively new and hitherto has remained an unexplored area of research. Use of macrophytes like Phragmites australis and Rheum rhabarbarum have shown efficient removal of Acid Orange 7 and sulfonated anthraquinones, respectively. Common garden and ornamental plants namely Aster amellus, Portulaca grandiflora, Zinnia angustifolia, Petunia grandiflora, Glandularia pulchella, many ferns and aquatic plants have also been advocated for their dye degradation potential. Plant tissue cultures like suspension cells of Blumea malcolmii and Nopalea cochenillifera, hairy roots of Brassica juncea and Tagetes patula and whole plants of several other species have confirmed their role in dye degradation. Plants' oxidoreductases such as lignin peroxidase, laccase, tyrosinase, azo reductase, veratryl alcohol oxidase, riboflavin reductase and dichlorophenolindophenol reductase are known as key biodegrading enzymes which break the complex structures of dyes. Schematic metabolic pathways of degradation of different dyes and their environmental fates have also been proposed. Degradation products of dyes and their fates of metabolism have been reported to be validated by UV-vis spectrophotometry, high performance liquid chromatography, high performance thin layer chromatography, Fourier Transform Infrared Spectroscopy, gas chromatograph-mass spectroscopy and several other analytical tools. Constructed wetlands and various pilots scale reactors were developed independently using the plants of P. australis, Portulaca grandiflora, G. pulchella, Typha domingensis, Pogonatherum crinitum and Alternanthera philoxeroides. The developed phytoreactors gave noteworthy treatments, and significant reductions in biological oxygen demand, chemical oxygen demand, American Dye Manufacturers Institute color removal value, total organic carbon, total dissolved solids, total suspended solids, turbidity and conductivity of the dye effluents after phytoremediation. Metabolites of dyes and effluents have been assayed for phytotoxicity, cytotoxicity, genotoxicity and animal toxicity and were proved to be non/less toxic than untreated compounds. Effective strategies to handle fluctuating dye load and hydraulics for in situ treatment needs scientific attention. Future studies on development of transgenic plants for efficacious phytodegradation of textile dyes should be focused.

New investigations into the genotoxicity of cobalt compounds and their impact on overall assessment of genotoxic risk

The genotoxicity of cobalt metal and cobalt compounds has been widely studied. Several publications show induction of chromosomal aberrations, micronuclei or DNA damage in mammalian cells in vitro in the absence of S9. Mixed results were seen in gene mutation studies in bacteria and mammalian cells in vitro, and in chromosomal aberration or micronucleus assays in vivo. To resolve these inconsistencies, new studies were performed with soluble and poorly soluble cobalt compounds according to OECD-recommended protocols. Induction of chromosomal damage was confirmed in vitro, but data suggest this may be due to oxidative stress. No biologically significant mutagenic responses were obtained in bacteria, Tk(+/-) or Hprt mutation tests. Negative results were also obtained for chromosomal aberrations (in bone marrow and spermatogonia) and micronuclei at maximum tolerated doses in vivo. Poorly soluble cobalt compounds do not appear to be genotoxic. Soluble compounds do induce some DNA and chromosomal damage in vitro, probably due to reactive oxygen. The absence of chromosome damage in robust GLP studies in vivo suggests that effective protective processes are sufficient to prevent oxidative DNA damage in whole mammals. Overall, there is no evidence of genetic toxicity with relevance for humans of cobalt substances and cobalt metal.

Green synthesis, photocatalytic and photoelectrochemical performance of an Au–Graphene nanocomposite

Visible light-induced photocatalytic degradation of pollutants using an Au–Graphene nanocomposite.

Genotoxicity testing of esterified propoxylated glycerol (EPG)

Four versions of esterified propoxylated glycerols (EPGs) were evaluated for potential genotoxicity using a range of in vitro and in vivo assays. H-EPG-05 HR/SO 9:1, H-EPG-05 soyate, and H-EPG-14 soyate were non-mutagenic in reverse mutation assays (maximum concentration 1000 μg/plate) using Salmonella typhimurium and Escherichia coli. Heated and unheated H-EPG-05 HR/SO 9:1 and EPG-05 HR/ST 45:55 were likewise non-mutagenic in reverse mutation assays in S. typhimurium strains TA98 and TA100 (maximum concentration 5000 μg/plate). H-EPG-05 HR/SO 9:1, H-EPG-05 soyate, and H-EPG-14 soyate, were devoid of mutagenic activity in a mouse lymphoma assay in L5178Y tk +/- cells (maximum concentration 200 μg/plate for H-EPG-05 HR/SO 9:1; 100 μg/plate for H-EPG-05 soyate and H-EPG-14 soyate), and a chromosomal aberration test using human lymphocytes (maximum concentration 50 μg/plate for H-EPG-05 HR/SO 9:1 and H-EPG-05 soyate; 60 μg/plate for H-EPG-14 soyate). All assays were conducted with and without metabolic activation. Additionally, H-EPG-05 HR/SO 9:1, H-EPG-05 soyate, and H-EPG-14 soyate were non-genotoxic in unscheduled DNA synthesis tests in rats (maximum dose 2000 mg/kg). Based on the results of these assays it was concluded that these versions of EPG were not genotoxic under any of the conditions of the assays performed.

TiO2-coated nanostructures for dye photo-degradation in water

The photocatalytic efficiency of a thin-film TiO2-coated nanostructured template is studied by dye degradation in water. The nanostructured template was synthesized by metal-assisted wet etching of Si and used as substrate for the deposition of a thin film of TiO2 (10 nm thick) by atomic layer deposition. A complete structural characterization was made by scanning and transmission electron microscopies. The significant photocatalytic performance was evaluated by the degradation of two dyes in water: methylene blue and methyl orange. The relevance of the reported results is discussed, opening the route toward the application of the synthesized nanostructured TiO2 for water purification.

Comparison of in vitro toxicity of mainstream cigarette smoke particulate matter from nano- to micro-size

In order to investigate the interrelationship between particulate matter (PM) size and in vitro toxicological effects of mainstream cigarette smoke, PM sized between 10 nm and 10 μm in mainstream cigarette smoke was sampled and divided into six stages. The in vitro cytotoxicity, genotoxicity and cell inhibition effects of PM were assessed by the neutral red cytotoxicity assay, Salmonella mutagenicity assay, micronucleus test and flow cytometry analysis, respectively. The results showed that all test samples were cytotoxic in the neutral red cytotoxicity assay. The IC50 values in the small-sized groups were significantly lower than those in the large-sized groups. Most test samples were mutagenic in the Salmonella mutagenicity assay (TA98 with S9 and TA100 with S9) and increased the frequency of micronucleated cells. Most PM disturbed the normal progression of the cell cycle, resulting in the accumulation of cells in the G0/G1 phase and the induction of apoptosis. In these tests, PM of a large size induced less toxicity compared with PM of a small size. These findings suggest that most PM samples induced toxicity in vitro, and PM of a small size was more toxic than PM of a large size.

Facile and rapid synthesis of a dithiol-protected Ag7 quantum cluster for selective adsorption of cationic dyes

We report a facile and rapid (less than 15 min) synthesis of atomically precise, dithiol-protected, silver quantum cluster, Ag7(DMSA)4 (DMSA: meso-2,3-dimercaptosuccinic acid), through a modified solid state route. The as-synthesized cluster exhibits molecular optical absorption features with a prominent λmax at ~500 nm. Composition of the cluster was confirmed using various spectroscopic and microscopic techniques such as electrospray ionization mass spectrometry (ESI MS), X-ray photoelectron spectroscopy (XPS), X-ray diffraction (XRD), Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), transmission electron microscopy (TEM), and energy dispersive analysis of X-rays (EDAX). Clusters supported on neutral alumina have been shown as better adsorbents for selective adsorption of cationic dyes (over anionic dyes) from water. This selectivity for cationic dyes was evaluated by zeta potential (ζ) measurements. The efficiency of clusters for removal of dyes is very high when compared to nanoparticles (NPs) protected with ligands (citrate and mercaptosuccinic acid (MSA)) possessing similar chemical structures as that of DMSA. The higher efficiency of clusters for the removal of dyes is attributed to their smaller size and large surface area compared to the NPs in addition to favorable electrostatic interactions between the clusters and cationic dyes. Adsorption of dyes (cationic and anionic) was enhanced when dye molecules contain hydrogen bond forming functional groups. Supported clusters have been reused up to five cycles without the loss of activity once the adsorbed dye is extracted using suitable solvents.

Short-Term Clinical Exposure Evaluation of a Second-Generation Electrically Heated Cigarette Smoking System

This randomized, controlled, forced-switching, open-label, parallel-group study in 100 adult male and female smokers of conventional cigarettes evaluated 8 biomarkers of tobacco smoke exposure. After baseline exposure determinations, adult smokers were switched to a second-generation electrically heated cigarette smoking system (EHCSS) for 8 days in a clinical setting. After 8 days of smoking the EHCSS biomarkers of exposure decreased by 43% to 85% compared to baseline. After correction for residual effects (carryover effects due to long elimination half-life and non-tobacco-confounding sources of exposure), reductions in exposure ranged from 59% to 97%. Results from this short-term clinical exposure study indicate that switching from a conventional cigarette to a second-generation electrically heated cigarette smoking system substantially reduced the exposure to several measured potentially harmful constituents of tobacco smoke.

Acid azo dye remediation in anoxic-aerobic-anoxic microenvironment under periodic discontinuous batch operation: bio-electro kinetics and microbial inventory

Functional behavior of anoxic-aerobic-anoxic microenvironment on azo dye (C.I. Acid black 10B) degradation was evaluated in a periodic discontinuous batch mode operation for 26 cycles. Dye removal efficiency and azo-reductase activity (30.50 ± 1 U) increased with each feeding event until 13th cycle and further stabilized. Dehydrogenase activity also increased gradually and stabilized (2.0 ± 0.2 μg/ml) indicating the stable proton shuttling between metabolic intermediates providing higher number of reducing equivalents towards dye degradation. Voltammetric profiles showed drop in redox catalytic currents during stabilized phase also supports the consumption of reducing equivalents towards dye removal. Change in Tafel slopes, polarization resistance and other bioprocess parameters correlated well with the observed dye removal and biocatalyst behavior. Microbial community analysis documented the involvement of specific organism pertaining to aerobic and facultative functions with heterotrophic and autotrophic metabolism. Integrating anoxic microenvironment with aerobic operation might have facilitated effective dye mineralization due to the possibility of combining redox functions.

In vitro cytotoxicity and mutagenicity of mainstream waterpipe smoke and its functional consequences on alveolar type II derived cells

INTRODUCTION

While waterpipe tobacco smoking has become a global phenomenon, its potential health consequences are poorly understood. In this manuscript, we report the in vitro mutagenicity of waterpipe smoke condensate (WSC), the alteration in cellular parameters of lung alveolar cells in response to WSC exposure and discuss the implication of cellular responses in the pathophysiology of chronic obstructive pulmonary disease (COPD).

METHODS

The mainstream WSC was generated using a standard laboratory machine protocol. We assessed its mutagenicity using Ames test. In addition, we studied the effect of WSC on the proliferation and cell cycle of alveolar type II cells and vascular endothelial cells. We also assessed the effect of WSC on the expression of genes involved in cell cycle arrest and inflammation.

RESULTS

Within the range of tested doses, WSC did not elicit sufficient response to be considered mutagenic in any of the strains tested (TA98, TA100, TA102, and TA97a) but were found to be toxic for strains TA97a and TA102 at the highest tested doses. However, WSC induced cell cycle arrest and cellular senescence mediated by the p53-p21 pathway. Also our study indicated that WSC induced an increase in the transcriptional expression of matrix metalloproteinases, MMP-2 and MMP-9 and an immune response regulator, Toll Like Receptor-4.

CONCLUSION

The data reported here represent the first in vitro demonstration of the effect of waterpipe smoke on cellular parameters providing evidence of the potential involvement of WPS in the pathogenesis of COPD through impairing cellular growth and inducing inflammation.

Assessment of by-products of chlorination and photoelectrocatalytic chlorination of an azo dye

The present work describes a more efficient methodology for the chlorination of water containing disperse dyes, where the chlorinated byproducts identified by mass spectra are compared. For this investigation, we tested the degradation of CI Disperse Blue 291 dye, 2-[(2-Bromo-4,6-dinitrophenyl)azo]-5-(diethylamino)-4-methoxyacetanilide) a commercial azo dye with mutagenic properties. The present work evaluates the photoelectrocatalytic efficiency of removing the CI Disperse Blue 291 dye from a wastewater of the textile industry. We employed NaCl as a supporting electrolyte. It should be noted that photoelectrocatalytic techniques are non-conventional method of generating chlorine radicals. The by-products formed in this process were analyzed using spectrophotometry, liquid chromatography, dissolved organic carbon, mass spectral analysis and mutagenicity assays. The process efficiency was compared with the conventional chlorination process adopted during sewage and effluents treatment processes. This conventional chlorination process is less efficient in removing color, total organic carbon than the photoelectrochemistry technique. Furthermore, we shall demonstrate that the mutagenicity of the generated by-products obtained using photoelectrocatalysis is completely different from that obtained by the conventional oxidation of chloride ions in the drinking water treatment process.

Suppression of error prone pathway is responsible for antimutagenic activity of honey

Honey, both unifloral (Syzygiumcumini) and bifloral, demonstrated strong antimutagenicity against physical (UV, γ) and chemical (ethylmethane sulfonate) mutagens as ascertained by rpoB/RifR and Ames tests. The effect of honey was evaluated in radiation (UV or γ) exposed Escherichia coli cells for SOS response, a well known error prone repair pathway known to significantly contribute to mutagenicity by quantifying LexA repressor level, measuring cell filamentation frequency, and prophage induction by SIVET (Selectable--In-Vivo Expression Technology) assay. LexA was almost completely degraded, phenotypically long filamentous cells (∼30 μm) were formed, and SIVET induction frequency was increased in radiation exposed E. coli cultures, however, these changes were significantly inhibited in presence of honey confirming its strong antimutagenic nature. Further, rpoB/RifR mutation frequency upon UV exposure in E. coli recA- cells was found to be negligible, whereas, E. coliumuC- and umuD- knockouts showed comparatively higher mutation frequency. Honey did not show any effect on mutagenesis in these knockouts, indicating the SOS dependence of the observed mutagenesis. Honey was also found to suppress EMS induced mutagenesis but through SOS independent mechanism. Phenolics present in honey were found to be one of the important factors contributing to the antimutagenicity of honey.

Subchronic toxicity and genotoxicity of diiodomethyl-p-tolylsulfone (DIMPTS) in laboratory animals

These studies were conducted to determine subchronic toxicity and genotoxicity of the biocide diiodomethyl-p-tolysulfone (DIMPTS) in rats and dogs. Male and female Sprague-Dawley rats and Beagle dogs were administered DIMPTS for 90-days via the diet at 0, 5, 20, and 80 mg/kg/day to rats and via capsules at 0, 2, 10, and 60 mg/kg/day to dogs. In rats, the only treatment-related finding was squamous metaplasia of the salivary gland duct in the 80 mg/kg/day group. In dogs, female body weights in the high-dose group were significantly lower than controls. Altered clinical pathology parameters were considered secondary to inflammatory changes observed in some of the dogs. Treatment-related alterations were found in the thyroid glands, salivary glands, GI-tract in the mid- and/or high-dose groups. DIMPTS was negative in the four in vitro and one in vivo genotoxicity assays. The toxicological effects noted in the two mammalian species are consistent with the principal toxic effects of iodine, and are proposed to arise from release of iodide from the DIMPTS molecule with toxic sequelae.

Bacterial mutagenicity assays: test methods

The most widely used assays for detecting chemically induced gene mutations are those employing bacteria. The plate incorporation assay using various Salmonella typhimurium LT2 and E. coli WP2 strains is a short-term bacterial reverse mutation assay specifically designed to detect a wide range of chemical substances capable of causing DNA damage leading to gene mutations. The test is used worldwide as an initial screen to determine the mutagenic potential of new chemicals and drugs.The test uses several strains of S. typhimurium which carry different mutations in various genes of the histidine operon, and E. coli which carry the same AT base pair at the critical mutation site within the trpE gene. These mutations act as hot spots for mutagens that cause DNA damage via different mechanisms. When these auxotrophic bacterial strains are grown on a minimal media agar plates containing a trace of the required amino-acid (histidine or tryptophan), only those bacteria that revert to amino-acid independence (His(+) or Tryp(+)) will grow to form visible colonies. The number of spontaneously induced revertant colonies per plate is relatively constant. However, when a mutagen is added to the plate, the number of revertant colonies per plate is increased, usually in a dose-related manner.This chapter provides detailed procedures for performing the test in the presence and absence of a metabolic activation system (S9-mix), including advice on specific assay variations and any technical problems.

Les colorants textiles sources de contamination de l’eau : CRIBLAGE de la toxicité et des méthodes de traitement

Les colorants sont largement utilisés dans les imprimeries, les produits alimentaires, cosmétiques et cliniques, mais en particulier dans les industries textiles pour leur stabilité chimique et la facilité de leur synthèse et leur variété de couleurs. Cependant, ces colorants sont à l’origine de la pollution une fois évacués dans l’environnement. La production mondiale des colorants est estimée à plus de 800 000 t•an-1et les colorants azoïques sont majoritaires et représentent 60-70 %. Compte tenu de la composition très hétérogène de ces derniers, leur dégradation conduit souvent à la conception d’une chaîne de traitement physique-chimique et biologique assurant l’élimination des différents polluants par étapes successives. Dés études ont montré que plusieurs colorants azoïques sont toxiques et mutagènes et le traitement biologique de ces colorants semble présenter un intérêt scientifique majeur. Les traitements physico-chimiques communs (adsorption, coagulation/floculation, précipitation etc.) sont couramment utilisés pour les effluents industriels. Malgré leur rapidité, ces méthodes se sont avérées peu efficaces compte tenu des normes exigées sur ces rejets. Le traitement biologique constitue une alternative fiable; en effet, plusieurs microorganismes sont capables de transformer les colorants azoïques en sous-produits incolores. Les bactéries dégradent les colorants azoïques en deux étapes : un clivage de liaison azo, par l’intermédiaire de l’azoréductase, suivi d’une oxydation des amines aromatiques formées lors de la première étape. L’azoréduction constitue alors une étape clé du traitement des effluents chargés de ces colorants.

A summary of toxicological and chemical data relevant to the evaluation of cast sheet tobacco

A tiered testing strategy based on a comparative chemical and biological testing program has been developed to evaluate the potential of tobacco processes, ingredients, or other technological developments to change the biological activity that results from burning tobacco. Cast sheet tobacco is a specific type of reconstituted tobacco sheet that can be used in the manufacture of cigarettes. The comparative chemical and biological testing program was used to compare the mainstream smoke and cigarette smoke condensate (CSC) from a Reference cigarette that did not contain cast sheet to that collected from Test cigarettes containing cast sheet at a final blend level of either 10% or 15%. Testing included mainstream cigarette smoke chemistry studies, in vitro studies (Ames assay, sister chromatid exchange assay, and neutral red cytotoxicity assay), and in vivo toxicology studies (13-week rat nose-only inhalation assay and 30-week mouse dermal tumor promotion assay). Certain statistically significant differences were observed in the chemical and biological studies when the Reference cigarette was compared to each of the Test cigarettes. However, when viewed collectively, the chemical and biological studies demonstrated that inclusion of cast sheet up to 15% in the final blend did not increase the inherent biological activity of mainstream cigarette smoke or CSC.

Mutagenicity and genotoxicity of acid yellow 17 and its biodegradation products

Acid yellow 17 (AY17), a very important commercial azo dye used in the textile industry, was degraded by Pseudomonas putida mt-2 at a concentration of up to 200 mg/L. High-performance liquid chromatography analysis of the biodegradation media revealed the presence of 4-aminobenzensulfonic acid (4-ABS) derived from AY17 azoreduction, which attests the expression of an azoreductase by this bacterium. This amine was identified only in the medium of static incubation, which is consistent with its biotransformation under shaken incubation (i.e., aerobic conditions). The mutagenicity of AY17 and its biodegradation products was evaluated by using Salmonella typhimurium TA102 and TA104. No mutagenicity was observed in the presence or absence of a metabolic activation system (S9). In addition, the ability of tested compounds to induce DNA damage in vitro with the DNA strand scission assay was evaluated. Results showed that only static decolorization culture of AY17 showed a significant ability to induce the pKS plasmid DNA opening. The present study showed that P. putida mt-2, cultivated under aerobic conditions, was able to decolorize, and especially to detoxify, AY17.