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Water radiolysis can serve as a useful tool to study the degradation of organic pollutants in water. Manipulation of the radiolytic system enables the selective production of reactive species (RS) with known yields. Our aim was to explore the effects of the radiolytically produced RS on commonly occuring water taste and odor compounds (T&O), 2-methylisoborneol (MIB) and geosmin (GSM). Observed degradation rate constants differ among experimental conditions/dominant RS and follow the order: HO•>H•>>eaq−>(O2−•/HO2•), ranging from 0.002 Gy−1 (O2−•/HO2•) to 0.083 Gy−1 (HO•) for MIB and from 0.006 Gy−1 (O2−•/HO2•) to 0.068 Gy−1 (HO•) for GSM. Degradation by HO• was very efficient, requiring 1.14 and 1.49 μmoles of HO• for each degraded μmole of MIB and GSM, respectively. The oxidative degradation of MIB by HO• proceeds with the production of carbonyl- and hydroxyl‑containing transformation products (TPs), leading to linear structures, while for GSM degradation proceeds with ring opening, followed by formation of carboxyl-groups. Fewer TPs are produced by HO2•, while degradation with H• led to numerous TPs, via dehydroxylation, dehydration and ring opening. Degradation with eaq−, yielded demethylated and rearranged TPs with formation of double bonds.

Pazla R, Jamarun N, Zain M, Yanti G, Chandra RH. 2021. Quality evaluation of tithonia (Tithonia diversifolia) with fermentation using Lactobacillus plantarum and Aspergillus ficuum at different incubation times. Biodiversitas 22: 3936-3942. This research aimed to evaluate the nutritional quality of tithonia (Tithonia diversifolia) fermented using Lactobacillus plantarum and Aspergillus ficuum with different incubation times on nutritional content, digestibility, phytase enzyme activity, and characteristics of rumen fluid. The research used an experimental method with a factorial completely randomized design to evaluate the nutritional content and phytase enzyme activity after fermentation (stage 1). A randomized block design was used to evaluate in vitro digestibility and rumen fluid characteristics (stage 2). For factorial completely randomized design, factor A is the type of microbe (L. plantarum and A. ficuum), then factor B is the incubation time (3,5,7 days). Parameters observed were the nutritional content of dry matter (DM), organic matter (OM), crude protein (CP), crude fiber (CF), and phytase enzyme activity. For the Randomized Block Design, the research treatments were A = A. ficuum + 5 days of incubation, B = A. ficuum + 7 days of incubation, C = L. plantarum + 3 days of incubation, D = L. plantarum + 5 days of incubation. Parameters measured were the digestibility of dry matter(DMD), organic matter (OMD), crude protein (CPD), crude fiber (CFD), rumen pH, VFA production, and NH3 rumen fluid. The results showed that there was an interaction between the type of microbe and incubation time. The treatment had a significantly different effect (P0.05) on DMD, OMD, CPD but had a significant effect (P0.05) on VFA but were significantly different (P

Cyanotoxins (CTs) produced by cyanobacteria in surface freshwater are a major threat for public health and aquatic ecosystems. Cyanobacteria can also produce a wide variety of other understudied bioactive metabolites such as oligopeptides microginins (MGs), aeruginosins (AERs), aeruginosamides (AEGs) and anabaenopeptins (APs). This study reports on the co-occurrence of CTs and cyanopeptides (CPs) in Lake Vegoritis, Greece and presents their variant-specific profiles obtained during 3-years of monitoring (2018–2020). Fifteen CTs (cylindrospermopsin (CYN), anatoxin (ATX), nodularin (NOD), and 12 microcystins (MCs)) and ten CPs (3 APs, 4 MGs, 2 AERs and aeruginosamide (AEG A)) were targeted using an extended and validated LC-MS/MS protocol for the simultaneous determination of multi-class CTs and CPs. Results showed the presence of MCs (MC-LR, MC-RR, MC-YR, dmMC-LR, dmMC-RR, MC-HtyR, and MC-HilR) and CYN at concentrations of &lt, 1 μg/L, with MC-LR (79%) and CYN (71%) being the most frequently occurring. Anabaenopeptins B (AP B) and F (AP F) were detected in almost all samples and microginin T1 (MG T1) was the most abundant CP, reaching 47.0 μg/L. This is the first report of the co-occurrence of CTs and CPs in Lake Vegoritis, which is used for irrigation, fishing and recreational activities. The findings support the need for further investigations of the occurrence of CTs and the less studied cyanobacterial metabolites in lakes, to promote risk assessment with relevance to human exposure.

Cyanobacteria are photosynthetic microorganisms distributed globally in aquatic and terrestrial environments. They are also industrially cultivated to be used as dietary supplements, as they have a high nutritional value; however, they are also known to produce a wide range of toxic secondary metabolites, called cyanotoxins. BMAA (β-methylamino-l-alanine) and its most common structural isomers, DAB (2,4-diaminobutyric acid) and AEG (N-2-aminoethylglycine) produced by cyanobacteria, are non-proteinogenic amino acids that have been associated with neurodegenerative diseases. A possible route of exposure to those amino acids is through consumption of food supplements based on cyanobacteria. The review critically discusses existing reports regarding the occurrence of BMAA, DAB and AEG in cyanobacteria and cyanobacteria-based food supplements. It is shown that inconsistencies in reported results could be attributed to performance of different methods of extraction and analysis applied and in ambiguities regarding determination of soluble and bound fractions of the compounds. The critical aspect of this review aims to grow awareness of human intake of neurotoxic amino acids, while results presented in literature concerning dietary supplements aim to promote further research, quality control as well as development of guidelines for cyanotoxins in food products.

Biological and advanced chemical treatment of cyanotoxins and other cyanobacteria-related contaminants such as taste and odor compounds, results in the formation of myriad transformation products (TPs) prior to their mineralization to simpler compounds such as H2O and CO2. This chapter gives an overview of the TPs formed for the major groups of cyanotoxins, with both biological and chemical treatment processes. In addition, it provides detailed explanations on the mechanistic steps followed that lead up to the formation of stable TPs for each oxidant used. It becomes apparent that besides the oxidizing ability of each oxidant, TP formation can be affected by the experimental conditions used, including oxidant and catalyst dose, solution pH, and presence of scavengers. Finally, the toxic potential of TPs is discussed.

The production of β-Ν-methylamino-L-alanine (BMAA) in cyanobacteria is triggered by nitrogen-starvation conditions and its biological role, albeit unknown, is associated with nitrogen assimilation. In the present study, the effect of BMAA (773 μg L−1) on nitrogen metabolism and physiology of the non-diazotrophic cyanobacterium and non-BMAA producer, Synechococcus sp. TAU-MAC 0499, was investigated. In order to study the combined effect of nitrogen availability and BMAA, nitrogen-starvation conditions were induced by transferring cells in nitrogen-free medium and subsequently exposing the cultures to BMAA. After short-term treatment (180 min) and in the presence of nitrogen, BMAA inhibited glutamine synthetase, which resulted in low concentration of glutamine. In the absence of nitrogen, although there was no effect on glutamine synthetase, a possible perturbation in nitrogen assimilation is reflected on the significant decrease in glutamate levels. During the long-term exposure (24–96 h), growth, photosynthetic pigments and total protein were not affected by BMAA exposure, except for an increase in protein and phycocyanin levels at 48 h in nitrogen replete conditions. Results suggest that BMAA interferes with nitrogen assimilation, in a different way, depending on the presence or absence of combined nitrogen, providing novel data on the potential biological role of BMAA.

This paper presents the first report of cyanobacteria and cyanotoxins from the South Caucasus region, in particular from Lake Yerevan (Armenia). Microcystis, Dolichospermum and Planktothrix were the key genera identified during the growing season. A trend of a remarkable increase in cyanobacterial densities was observed from 2012 to 2013 exhibiting bloom formation in June (by Nostoc linckia) with the highest values in June and August 2013, reaching up to 695.9*103 cells mL−1. Seasonal dependence of cyanobacterial density on temperature, and temperature as a driver for cyanobacterial cells growth and development were suggested. Biogenic nutrients were identified as co-drivers determining species richness and dominance, as well as the distribution of phytoplankton in different parts of the reservoir. Cyanotoxin concentrations in the filtered biomass were reported during July 2012 for both stations of the reservoir (left and right bank). Microcystin-RR (MC-RR) was the most abundant and the most frequently observed cyanotoxin. Lower MC-LR concentrations were identified in all samples from both stations, with the highest values observed at the right bank in July 2012. [D-Asp3]MC-RR, MC-YR, MC-HtyR, [D-Asp3]MC-LR, MC-HilR, MC-WR, MC-LY and MC-LW were also identified in trace levels. Anatoxin-a (ANA) was reported in the samples from both stations during August 2012. Cylindrospermopsin (CYN) was present in trace concentrations in samples from both stations during July and in the sample from the left bank during September.

Insight into how environmental change determines the production and distribution of cyanobacterial toxins is necessary for risk assessment. Management guidelines currently focus on hepatotoxins (microcystins). Increasing attention is given to other classes, such as neurotoxins (e.g., anatoxin-a) and cytotoxins (e.g., cylindrospermopsin) due to their potency. Most studies examine the relationship between individual toxin variants and environmental factors, such as nutrients, temperature and light. In summer 2015, we collected samples across Europe to investigate the effect of nutrient and temperature gradients on the variability of toxin production at a continental scale. Direct and indirect effects of temperature were the main drivers of the spatial distribution in the toxins produced by the cyanobacterial community, the toxin concentrations and toxin quota. Generalized linear models showed that a Toxin Diversity Index (TDI) increased with latitude, while it decreased with water stability. Increases in TDI were explained through a significant increase in toxin variants such as MC-YR, anatoxin and cylindrospermopsin, accompanied by a decreasing presence of MC-LR. While global warming continues, the direct and indirect effects of increased lake temperatures will drive changes in the distribution of cyanobacterial toxins in Europe, potentially promoting selection of a few highly toxic species or strains. © 2018 by the authors. Licensee MDPI, Basel, Switzerland., The authors acknowledge COST Action ES 1105 “CYANOCOST—Cyanobacterial blooms and toxins in water resources: Occurrence impacts and management” and COST Action ES 1201 “NETLAKE—Networking Lake Observatories in Europe” for contributing to this study through networking and knowledge sharing with European experts in the field. Evanthia Mantzouki was supported by a grant from the Swiss State Secretariat for Education, Research and Innovation (SERI) to Bas Ibelings and by supplementary funding from the University of Geneva. We thank Clare Ahnlund, Ena Suarez and Irene Gallego for helping out with the Swiss survey. We thank Wendy Beekman and Els J. Faassen for the nutrient and toxin analysis.

Lauril amide is one of nonionic surfactant and has potency to become an ecofriendly surfactant. The main problem on lauril amide synthesis is the low conversion of lauric acid. Optimation of lauril amide synthesis is done with three variabels which give influence of amidation reaction. One stage amidation was done by reacting lauric acid with diethanolamine using catalyst Novozyme 435® with substrate ratio lauric acid:diethanolamine 1:1; 2:1; 3:1; 4:1; 5:1, amount of catalyst 1,8; 4; 7; 10; 11,8% from lauric acid total amount, solvent ratio 0; 1:1; 2:1; 3:1; 4:1 from lauric acid total amount and reacted for 24 hours with temperature reaction 55oC and 500 rpm. Product is separated from catalyst using filtration method and then purified by washing with acetone and heated at temperature of 90 oC to remove solvent. Product has been analyzed with acid value to obtained percent conversion of lauril amide, determine of Hydrophilic Liphophilic Balance value, spectroscopy Fourier Transform Infrared and determine of critical micelle concentrasion. Percent conversion optimum has obtained 86,16% at condition substrate ratio 1:1, enzyme concentration Novozyme 435® 7% and solvent ratio 2:1. Analysis result of lauril amide surfactant gave the hidrophile liphophile balance value about 11,93, it means that lauril amide surfactant can be used as emultion oil in water.

Carbohydrate ester is one of many needed nonionic surfactant groups and has the potential to be an environmental friendly surfactant. The principal problem in the synthesis of carbohydrate ester is to obtain the optimum conversion of palmitic acid from temperature influence, the amount of biocatalyst and reaction time. The optimization of carbohydrate ester synthesis is carried out on three variables that influence the esterification reaction. Therefore, the esterification process is carried out by reacting directly the palmitic acid and fructose using a Novozyme®435 an immobilized lipase enzyme catalyst with a free variable of reaction temperature of 41,5 oC, 45 oC, 50 oC, 55 oC, 58,4 oC, the amount of biocatalyst is 6,63%, 8%, 10%, 12%, 13,36% mass based palmitic acid also reaction time of 7,6 hours; 24 hours; 48 hours; 72 hours; 88,3 hours and reacted with fixed variable in 500 rpm; 3:1 substrate ratio (fructose:palmitic acid) and solvent amount 10 ml. The mixture is then separated from the catalyst by filtration. The product was analyzed with determination of acid number to obtain conversion percent of fructose ester, determination of Hydrophilic Lipophilic Balance, Fourier Transform Infrared (FTIR) an surface tension determination. The optimum conversion rate obtained is 61,80% at 55 oC of reaction temperature, Novozyme®435 enzyme count is 12% and 72 hours of reaction time. From the result of fructose ester surfactant analysis obtained HLB 10,592 value which showed fructose ester surfactant can be used as emulsifier of oil in water.

5',8-Cyclo-2'-deoxyadenosine (cdA) and 5',8-cyclo-2'-deoxyguanosine (cdG) in their two diastereomeric forms, 5'S and 5'R, are tandem lesions produced by the attack of hydroxyl radicals to the purine moieties of DNA. Their formation has been found to challenge the cells' repair machinery, initiating the nucleotide excision repair (NER) for restoring the genome integrity. The involvement of oxidatively induced DNA damage in carcinogenesis and the reduced capacity of some cancer cell lines to repair oxidised DNA base lesions, intrigued us to investigate the implication of these lesions in breast cancer, the most frequently occurring cancer in women. Using liquid chromatography tandem mass spectrometry (LC-MS/MS), we measured the levels of diastereomeric cdA's and cdG's in estrogen receptor-alpha positive (ER-alpha) MCF-7 and triple negative MDA-MB-231 breast cancer cell lines before and after exposure to two different conditions: ionising radiations and hydrogen peroxide, followed by an interval period to allow DNA repair. An increase at the measured levels of all four lesions, i.e. 5'S-cdA, 5'R-cdA, 5'S-cdG and 5'R-cdG, was observed either after gamma-irradiation (5Gy dose) or hydrogen peroxide treatment (300muM) compared to the untreated cells (control), independently from the length of the interval period for repair. For comparison reasons, we also measured the levels of 8-oxo-2'-deoxyadenosine (8-oxo-dA), a well-known oxidatively induced DNA damage lesion and base excision repair (BER) substrate. The collected data indicate that MCF-7 and MDA-MB-231 breast cancer cells are highly susceptible to radiation-induced DNA damage, being mainly defective in the repair of these lesions.

The investigation of conditions allowing multi-electron reduction and reoxidation of polyoxometalate (POM) films onto solid substrates is considered an issue of critical importance for their successful incorporation in electronic devices, different types of sensors and catalytic systems. In the present paper, the rich multi-electron redox chemistry of films of Wells–Dawson ammonium salts, namely (NH4)6P2Mo18O62 and (NH4)6P2W18O62, on top of metallic (Al), semiconducting (ITO) and dielectric (SiO2) substrates under ambient conditions is investigated. The respective Keggin heteropolyacids, H3PMo12O40 and H3PW12O40, are also investigated for comparison. On Al substrates, the Wells–Dawson ammonium salts are found to be significantly more reduced (4–6e−) compared to the respective Keggin heteropolyacids (∼2e−), in accordance with their deeper lying lowest unoccupied molecular orbital (LUMO) level. Subsequent thermal treatment in air results in reoxidation of the initially highly reduced POM films. Similar behavior is found on ITO substrates, but in initially less reduced (2–4e−) Wells–Dawson POM films. On the other hand, on SiO2 substrates, the thermal reduction of (NH4)6P2Mo18O62 film is observed and attributed to the thermal oxidation of ammonium counterions by [P2Mo18O62]6− anions. Overall, the multi-electron reduction of Wells–Dawson ammonium salts onto metallic and semiconducting substrates (Al, ITO) is determined by the relative position of the LUMO level of POMs in relation to the Fermi level of the substrate (i.e. substrate work function) and affected in a synergistic way by the presence of ammonium counterions. In contrast, on dielectric substrates (SiO2) the reduction of Wells–Dawson POMs ((NH4)6P2Mo18O62) is attributed only to the oxidation of ammonium counterions.

Visible light (VIS) photocatalysis has large potential as a sustainable water treatment process, however the reaction pathways and degradation processes of organic pollutants are not yet clearly defined. The presence of cyanobacteria cause water quality problems since several genera can produce potent cyanotoxins, harmful to human health. In addition, cyanobacteria produce taste and odor compounds, which pose serious aesthetic problems in drinking water. Although photocatalytic degradation of cyanotoxins and taste and odor compounds have been reported under UV-A light in the presence of TiO2, limited studies have been reported on their degradation pathways by VIS photocatalysis of these problematic compounds. The main objectives of this work were to study the VIS photocatalytic degradation process, define the reactive oxygen species (ROS) involved and elucidate the reaction mechanisms. We report carbon doped TiO2 (C-TiO2) under VIS leads to the slow degradation of cyanotoxins, microcystin-LR (MC-LR) and cylindrospermopsin (CYN), while taste and odor compounds, geosmin and 2-methylisoborneol, were not appreciably degraded. Further studies were carried-out employing several specific radical scavengers (potassium bromide, isopropyl alcohol, sodium azide, superoxide dismutase and catalase) and probes (coumarin) to assess the role of different ROS (hydroxyl radical OH, singlet oxygen (1)O2, superoxide radical anion [Formula: see text] ) in the degradation processes. Reaction pathways of MC-LR and CYN were defined through identification and monitoring of intermediates using liquid chromatography tandem mass spectrometry (LC-MS/MS) for VIS in comparison with UV-A photocatalytic treatment. The effects of scavengers and probes on the degradation process under VIS, as well as the differences in product distributions under VIS and UV-A, suggested that the main species in VIS photocatalysis is [Formula: see text] , with OH and (1)O2 playing minor roles in the degradation.

The present study was launched as a continuation of global efforts to tackle problems associated with two important aesthetic characteristics, taste and odor (T&O), of drinking water. The UV-A/Chlorine process, a promising advanced oxidation process (AOP), was evaluated for the first time for the removal of 2-isopropyl-3-methoxy pyrazine (IPMP), a widely reported compound in the literature that causes unpleasant taste and odor when present in water at or below the ng L-1 level. It was found that the studied process was efficient for the removal of IPMP in both ultrapure and drinking water. The initial chlorine dosage influenced significantly the degradation efficiency under initial neutral pH values. Degradation efficiency of IPMP was slightly inhibited by using drinking water as matrix. Scavenging experiments highlighted the significant role of various reactive species (e.g. HO, ClO, Cl, Cl2-) generated during the process that have not been studied comprehensively until now. In addition, the significant role of HO was further verified by Electron paramagnetic resonance spectroscopy (EPR) experiments. Overall, the formation of diverse radicals during the UV-A/Chlorine treatment enhanced the degradation of IPMP, promoting mainly the formation of hydroxy, hydroperoxy and dealkylated derivatives. In contrast, chlorinated by-products were only identified in traces.

Cyanobacteria can form extensive blooms in water with concurrent production and release of a large number of chemically diverse and bioactive metabolites, including hazardous toxins. Significant number of the metabolites belongs to non-ribosomal peptides, with unique residues, unusual structures and great potential for biotechnological application. The biosynthetic pathways of the peptides generate tens of variants, but only part of them has been identified. Microginins are an understudied class of cyanobacterial linear peptides with a characteristic decanoic acid derivative amino acid residue in their structure. In this study, cyanobacterial blooms and isolated strains from Greek lakes were analyzed for the presence of microginins by liquid chromatography coupled to hybrid triple quadrupole/linear ion trap mass spectrometer (LC-qTRAP MS/MS). Microginin structures were elucidated based on the obtained fragmentation spectra. A large number of microginins occurred in blooms of Greek freshwaters and the most frequently detected were Microginin FR1 (70% of samples), Microginin T1 (52%), Microginin 565B (52%), Microginin T2 (43%), and Microginin 565A (43%). Additionally, nine cyanobacterial strains i.e. Nostoc oryzae, Synechococcus sp., Microcystis aeruginosa, Microcystis viridis, and five Microcystis sp., were found to produce microginins. Thirty-six new microginin structures were characterized out of fifty-one totally detected variants. This is the first time that such a diversity of microginins is reported to be present in water bodies. Results clearly demonstrate the great metabolomic potential of cyanobacteria that inhabit Greek freshwaters and significantly expand the knowledge of cyanobacterial secondary metabolites with regards to the class of microginins.

Research on the development of new TiO2 based photocatalysts has been receiving increased attention due to the ability of TiO2 to degrade a great variety of organic compounds upon UV-A irradiation. In order to evaluate the photocatalytic performance of the new synthesized materials, it is essential to follow specific procedures during the photocatalytic process. Special care should be given on light intensity, presence of oxygen, catalyst loading, initial concentration of substrate, adsorption, pH, different irradiation wavelength, mineralization, intermediate products and toxicity. In this study, catalysts such as commercially available materials (Degussa P25, Kronos vlp-7000) and home prepared materials (N-TiO2, GO–TiO2 and Ref-TiO2) have been tested for their photocatalytic ability on the degradation and mineralization of the cyanobacterial toxin microcystin-LR and off-odor causing compounds (geosmin, 2-methylisoborneol) under UV-A, solar and visible light irradiation. Also, the identification of intermediate products and their toxicity under different experimental conditions for microcystin-LR was studied. Our results showed that in all cases of the compounds Degussa P25 was the better performing catalyst under UV-A light irradiation. Under solar light, all compounds were effectively degraded with the doped materials (N-TiO2, GO–TiO2, Kronos vlp-7000) showing better photocatalytic performance than theirs undoped material (Ref-TiO2). As far as concerning visible light irradiation, only the visible light activated materials showed some photocatalytic activity (N-TiO2, Kronos vlp-7000). It was also showed in order to have reproducible evaluation results on the photocatalytic performance of several catalysts (intra and inter-laboratory), a careful selection of experimental parameters is required.

Lake Karla (Central Greece) is a unique example - at European scale - of a shallow lake ecosystem that was dried in the 1960s and in 2009 started to be restored. The lake is listed in the network of the Greek protected areas as it is considered a vital aquatic ecosystem, in terms of biodiversity. It has, however, already been adversely affected by both agricultural and industrial land uses in the surrounding area, leading to eutrophication and shifting algal community towards bloom-forming toxic cyanobacterial species. After repeated heavy-blooms, cyanotoxin occurrence and mass fish kills, the local ecosystem management authority has implemented a water quality monitoring program (July 2013 - July 2015) to assess environmental pressures and the response of aquatic biota in the lake. Microscopic, immunological, and molecular techniques combined with physico-chemical parameters, complemented by liquid chromatography tandem mass spectrometry (LC-MS/MS), were used to monitor cyanobacteria blooms and the associated cyanotoxin production from three different sites in Lake Karla and from the adjacent Kalamaki Reservoir. Water quality was also assessed by the structure of benthic invertebrate community on the sediment. Cyanobacteria were the main phytoplankton component, representing more than 70% of the total phytoplankton abundance; dominant taxa belonged toCylindrospermopsis raciborskii,Limnothrix redekei,Anabaenopsis elenkinii, andMicrocystisspp. Euglenophytes (Euglena), diatoms (Nitzschia), and chlorophytes (Scenedesmus) were also important phytoplankton constituents. LC-MS/MS confirmed the co-occurrence of microcystins, cylindrospermopsin, saxitoxin, neo-saxitoxin and anatoxin-a. The occurrence of cyanotoxins in relation to the persistent and dominant cyanobacteria and the impact of cyanobacterial harmful algal blooms on the newly constructed lake along with the land uses and the emergent mitigation measures are discussed.&nbsp

Geosmin (GSM) and 2-methylisoborneol (MIB) are produced by several species of cyanobacteria and actinomycetes. These compounds can taint water and fish causing undesirable taste and odours. Studies have shown that GSM/MIB are resistant in standard water treatments. Polyoxometalates (POM) are efficient photocatalysts in the degradation and mineralization of a great variety of organic pollutants, presenting similar behaviour with the widely published titanium dioxide (TiO 2 ). Photocatalytic degradation of GSM and MIB under UV-A light in the presence of a characteristic POM photocatalyst, SiW 12 O 40 4− , in aqueous solution has been studied and compared with the photodegradation by TiO 2 suspensions. GSM and MIB are effectively degraded in the presence of both photocatalysts. Addition of OH radical scavengers (KBr and tertiary butyl alcohol, TBA) retards the photodegradation rates of both compounds, suggesting that photodegradation mechanism takes place via OH radicals. Intermediates identified using GC–MS in the case of GSM and MIB, are mainly identical in the presence of both photocatalysts, also suggesting a common reaction mechanism. Possible photocatalytic degradation pathway for both GSM and MIB is proposed.

Increased rates of reactive oxygen/nitrogen species (ROS/RNS) are involved in almost all cancer types, associated with tumor development and progression, causing damage to biomolecules such as proteins, nucleic acids and membrane lipids, in different biological compartments. We used a human tumor xenograft mouse model to evaluate for the first time in parallel the remodeling of fatty acid moieties in erythrocyte membrane phospholipids and the level of ROS-induced DNA lesions in liver and kidney tissues. Using liquid chromatography tandem mass spectrometry the 5&rsquo, R and 5&rsquo, S diastereoisomers of 5&rsquo, 8-cyclo-2&rsquo, deoxyadenosine and 5&rsquo, deoxyguanosine, together with 8-oxo-7,8-dihydro-2&rsquo, deoxyadenosine, were determined in mice at young (4- and 5-weeks) and old (17-weeks) ages and compared with control SCID mice without tumor implantation. Tumor-bearing mice showed a higher level of ROS-damaged nucleosides in genomic DNA as the age and tumor progress, compared to controls (1.07&ndash, 1.53-fold in liver and 1.1&ndash, 1.4-fold in kidney, respectively). The parallel fatty acid profile of erythrocyte membranes showed a profound lipid remodeling during tumor and age progression consisting of PUFA consumption and SFA enrichment (ca 28% and 58%, respectively, in late stage tumor-bearing mice), markers of enhanced oxidative and proliferative processes, respectively. Membrane lipid remodeling and ROS-induced DNA lesions may be combined to afford an integrated scenario of cancer progression and ageing, reinforcing a holistic vision among molecular markers rather than the biomarker identification in a single compartment.

Microcystin-LR (MC-LR) is the most common and toxic variant of the group of microcystins (MCs) produced during the formation of harmful cyanobacterial blooms. Geosmin (GSM) and 2-methylisoborneol (...

Exposure to beta-N-methylamino-l-alanine (BMAA) might be linked to the incidence of amyotrophic lateral sclerosis, Alzheimer's disease and Parkinson's disease. Analytical chemistry plays a crucial role in determining human BMAA exposure and the associated health risk, but the performance of various analytical methods currently employed is rarely compared. A CYANOCOST initiated workshop was organized aimed at training scientists in BMAA analysis, creating mutual understanding and paving the way towards interlaboratory comparison exercises. During this workshop, we tested different methods (extraction followed by derivatization and liquid chromatography coupled to tandem mass spectrometry (LC-MS/MS) analysis, or directly followed by LC-MS/MS analysis) for trueness and intermediate precision. We adapted three workup methods for the underivatized analysis of animal, brain and cyanobacterial samples. Based on recovery of the internal standard D(3)BMAA, the underivatized methods were accurate (mean recovery 80%) and precise (mean relative standard deviation 10%), except for the cyanobacterium Leptolyngbya. However, total BMAA concentrations in the positive controls (cycad seeds) showed higher variation (relative standard deviation 21%-32%), implying that D(3)BMAA was not a good indicator for the release of BMAA from bound forms. Significant losses occurred during workup for the derivatized method, resulting in low recovery (

Cyanobacterial and algal toxins comprise a large group of harmful metabolites, belonging to different chemical classes, with a variety of chemical structures, physicochemical properties and toxic activities. In this study, a fast, simple and sensitive analytical method was developed for the simultaneous determination of multi-class cyanobacterial and algal toxins in water. The target compounds were: Cylindrospermopsin, Anatoxin-a, Nodularin, 12 Microcystins ([D-Asp3]MC-RR, MC-RR, MC-YR, MC-HtyR, [D-Asp3]MC-LR, MC-LR, MC-HilR, MC-WR, MC-LA, MC-LY, MC-LW and MC-LF), Okadaic acid and Domoic acid. Analytes were determined using liquid chromatography-tandem mass spectrometry (LC-MS/MS). A dual Solid Phase Extraction (SPE) cartridge assembly was applied for the extraction of target compounds from water. Optimized SPE parameters included cartridge material, initial sample pH, sequence of the cartridges in the SPE assembly as well as composition and volume of the elution solvent. The method was validated, providing acceptable mean recoveries and reproducibility for most analytes. Limits of detection were at the ngL-1 level. The method was successfully applied in real lake water samples from Greece, where a wide range of Microcystins were detected for the first time, at concentrations ranging from 0.034 to 63μgL-1.

This chapter discusses thoroughly the outcomes of the TiO2 photocatalytic degradation of organic contaminants of emerging concern, including manmade (insecticides, organochlorinated compounds, and antibiotics) and naturally occurring compounds (cyanotoxins and taste and odor compounds). Specifically, information is provided on the degradation of various organic contaminants in actual water samples, their corresponding reaction kinetics, the individual effects of water quality parameters (including pH, natural organic matter, and alkalinity) and nano-interfacial adsorption phenomena. Emphasis is given to the mechanisms of photocatalytic degradation of organic contaminants based on their structural differences and the corresponding transformation products formed.

Cyanobacteria blooms pose an environmental hazard because of the release of water soluble toxic compounds, called cyanotoxins. Microcystins (MCs), hepatotoxic cyclic peptide toxins, are the most widespread cyanotoxins with microcystin-LR (MC-LR) the most common and toxic variant. Health effects of MCs have resulted in the need of using efficient treatment methods for the removal of this class of toxins in water supplies. While physical treatment methods can remove MCs at full or some extent from contaminated water, their function is primary separation of the whole toxins as intact molecules and further processing is required. On the other hand, chemical oxidation processes are a promising alternative treatment option due to the potential of complete destruction of the MCs, transformation to less toxic by-products, and even complete mineralization. MCs reactivity towards different conventional oxidants is strongly affected by water quality parameters like pH, DOC and oxidant dose. Although there is a general trend for MCs oxidation (ozone > permanganate > chlorine >>> chlorine-based oxidants), the selection of the appropriate oxidant for toxin elimination during water treatment should be assessed for each particular source of water. Although advanced oxidation processes are generally more effective on MCs degradation than conventional oxidation processes, scale-up studies are needed before these methods are considered as economically-feasible and practical sustainable alternatives in water treatment facilities. In this review, recent literature concerning treatment of MCs in water by conventional and advanced oxidation processes are reviewed and discussed in terms of the degree of degradation, reaction kinetics, identity and toxicity of oxidation by-products and possible degradation pathways.

The destruction of the commonly found cyanobacterial toxin, microcystin-LR (MC-LR), in surface waters by UV-C/H2O2 advanced oxidation process (AOP) was studied. Experiments were carried out in a bench scale photochemical apparatus with low pressure mercury vapor germicidal lamps emitting at 253.7 nm. The degradation of MC-LR was a function of UV fluence. A 93.9% removal with an initial MC-LR concentration of 1 μM was achieved with a UV fluence of 80 mJ/cm2 and an initial H2O2 concentration of 882 μM. When increasing the concentration of MC-LR only, the UV fluence-based pseudo-first order reaction rate constant generally decreased, which was probably due to the competition between by-products and MC-LR for hydroxyl radicals. An increase in H2O2 concentration led to higher removal efficiency; however, the effect of HO scavenging by H2O2 became significant for high H2O2 concentrations. The impact of water quality parameters, such as pH, alkalinity and the presence of natural organic matter (NOM), was also studied. Field water samples from Lake Erie, Michigan and St. Johns River, Florida were employed to evaluate the potential application of this process for the degradation of MC-LR. Results showed that the presence of both alkalinity (as 89.6–117.8 mg CaCO3/L) and NOM (as ∼2 to ∼9.5 mg/L TOC) contributed to a significant decrease in the destruction rate of MC-LR. However, a final concentration of MC-LR bellow the guideline value of 1 μg/L was still achievable under current experimental conditions when an initial MC-LR concentration of 2.5 μg/L was spiked into those real water samples.

A 9-week feeding trial was conducted to investigate the effects of dietary Enteromorpha prolifera on the growth performance and body composition of juvenile large yellow croaker (Pseudosciaena crocea) (Richardson, 1846) (11.41 ± 1.59 g) in floating sea cages (1.5 × 1.5 × 2.0 m). Four isonitrogenous and isoenergetic diets were formulated to contain graded levels (0%, 5%, 10% and 15%) of E. prolifera. Survival ranged from 98.7% to 99.7%, and was independent of dietary treatment (P>0.05). There were no significant differences in the feeding rate among dietary treatments (P>0.05). The specific growth rate (SGR) increased with increasing levels of E. prolifera. When the supplementation of E. prolifera was >5%, SGR was significantly higher compared with the control group (0%). The feed efficiency ratio (FER) in fish fed the diet with 5%E. prolifera (diet 2) was higher than that of the other groups, while in fish fed the diet with 10%E. prolifera (diet 3), it was the lowest (P

Anatoxin-a is a potent alkaloid neurotoxin produced by a number of cyanobacterial species and released in freshwaters during cyanobacterial blooms. Its high toxicity is responsible for several incidents of lethal intoxications of birds and mammals around the world; therefore anatoxin-a has to be regarded as a health risk and its concentration in lakes and water reservoirs should be monitored. Phenylalanine is a natural amino acid, also present in freshwaters, isobaric to anatoxin-a, with a very similar fragmentation pattern and LC retention. Since misidentification of phenylalanine as anatoxin-a has been reported in forensic investigations, special care must be taken in order to selectively determine traces of anatoxin-a in the presence of naturally occurring phenylalanine. A fast LC tandem MS method was developed by using a 1.8 microm 50 x 2.1 mm C18 column for the separation of anatoxin-a and phenylalanine, achieving a 3-min analysis time. Isotopically labelled phenylalanine-d(5) was employed as internal standard to compensate for electrospray ion suppression and sample preconcentration losses. Both compounds were preconcentrated 1,000-fold on a porous graphitic carbon solid-phase extraction (SPE) cartridge after adjustment of sample pH to 10.5. The method was validated by using lake water spiked at four different levels from 0.01 to 1 microg L(-1). Anatoxin-a recovery ranged from 73 to 97%, intra-day precision (RSD%) ranged from 4.2 to 5.9, while inter-day precision (RSD%) ranged from 4.2 to 9.1%. Limits of detection and quantification were 0.65 and 1.96 ng L(-1) respectively. The method was successfully applied for the detection of anatoxin-a in Greek lakes at concentrations ranging from less than 0.6 to 9.1 ng L(-1).

The photocatalytic degradation of lindane (γ-1,2,3,4,5,6-hexachlorocyclohexane) has been studied in the presence of the polyoxometalate PW12O403− in aqueous solutions. Lindane is fully decomposed to CO2, Cl− and H2O, while a great variety of intermediates has been detected using GC–MS, including aromatic compounds (dichlorophenol, trichlorophenols, tetrachlorophenol, hexachlorobenzene, di- and trichloro-benzenodiol), non-aromatic cyclic compounds (penta-, tetrachlorocyclohexene, heptachlorocyclohexane), aliphatic compounds (tetrachloroethane) and condensation products (polychlorinated biphenyls). The number and nature of the intermediates implies that the mechanism of decomposition of lindane is based on both oxidative and reductive processes. Common intermediates have been reported during photolysis of lindane in the presence of titanium dioxide. A similar overall mechanism of polyoxometalates and TiO2 photocatalysis through the formation of common reactive species is suggested.

Selenium nanoparticles are formed upon photolysis of solutions of (propan-2-ol/POM/Se(IV)), where polyoxometalate (POM) is either PW 12 O 40 3− or SiW 12 O 40 4− . Propan-2-ol serves as sacrificial reagent for the photoformation of 1-equivalent reduced blue polyoxometalate, POM(e), which further reacts with Se(IV) to produce selenium nanoparticles. POM serves both as relay for the transfer of electrons from propan-2-ol to Se(IV) and stabilizer for the nanoparticles. Changing the ionic strength from 0 to 0.025 and 0.05 M, results in the formation of gradually larger nanoparticles 40, 60 and 90 nm, respectively. Increase of the initial concentration of SiW 12 O 40 4− , from 2 to 4 and 10 × 10 −3 M, results in the formation of gradually smaller nanoparticles, 110, 80 and 60 nm, respectively.

Uniform silver nanoparticles were obtained upon the reduction of silver ions by reduced polyoxometalates (POMs) by simple mixing at room temperature. Control of the size and the dispersity of silver nanoparticles was achieved by rate control. Faster reduction of Ag+ led to smaller and more uniform silver nanoparticles, suggesting that the rate of Ag+ reduction strongly affects the initial nucleation of silver particles. A faster rate is achieved by either (i) increasing the concentration of the reducing reagent (reduced POM) or, more interestingly (ii) selecting POMs having appropriate (more negative) redox potentials: different POMs with increasing negative reduction potential or the same POM with more electrons accumulated on it. The rates of Ag+ reduction parallel the more negative reduction potential for POMs according to the series H2W12O407– > SiW12O405– > P2W18O628– > P2W18O627– > P2Mo18O6210– > P2Mo18O628– = 0. This precise redox-control is summarized in a log k (E0) electrochemical-like behavior, in alliance to a “soluble cathode” behavior of POMs, which leads to more uniform particles than those obtained with conventional electrochemistry. Alternatively, the concentration of silver ions influences the size of the particles obtained: increasing the amount of Ag+ leads to larger nanoparticles.(© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2008)

A new method for the simultaneous determination of 1,4-dichlorobenzene (p-DCB), naphthalene and 1,2-dibromoethane (1,2-DBE) residues in honey has been developed. Analysis is carried out using gas chromatography-mass spectrometry (GC/MS) in selected ion monitoring mode (SIM), after extraction and preconcentration of target analytes by headspace solid-phase microextraction (HS-SPME), with a 100 microm film thickness polydimethylsiloxane (PDMS) fiber. Several parameters affecting the extension of the adsorption process (i.e., addition of salt, extraction time, extraction temperature) were studied. The optimal conditions for the determination of these analytes were established. The proposed HS-SPME method showed good sensitivity, without carryover between the samples. Linearity was studied from 5 to 2500 microg kg(-1) for p-DCB, 0.5 to 500 microg kg(-1) for naphthalene and 5 to 500 microg kg(-1) honey for 1,2-DBE with correlation coefficients (r(2)) ranging from 0.9901 to 0.9999. Precision was assessed and both intra and inter-day R.S.D.s (%) were below 6.3%. The detection limits were found to be 1, 0.1 and 2 microg kg(-1) honey for p-DCB, naphthalene and 1,2-DBE, respectively. The percentage recoveries that were evaluated with the proposed HS-SPME method and the standard addition calibration technique gave values among 72.8 and 104.3% for measurements in samples spiked with one target analyte or mixtures of the three. This method has been applied for the analysis of unknown honey samples. The results showed an excellent applicability of the proposed method for the determination of the target compounds in honey samples.

Polyoxometallates (POMs) as a homogeneous photocatalyst and TiO2 as a heterogeneous photocatalyst seem to exhibit overall similar photocatalytic behavior. Both systems cause photodecomposition of a variety of organic pollutants via the formation and decay of several similar intermediates formed by OH addition (hydroxylation), dehalogenation, deamination, decarboxylation, etc. The final degradation products, for most organic substrates for both systems are CO2, H2O and inorganic anions. The similarity of behavior has been attributed to the formation of the common powerful oxidizing reagent, OH radical, from the reaction of the excited catalyst and water molecules. On the other hand, lately, various laboratories have pointed out differences in reactivity and degradation mechanism between the two photocatalysts. The results are interesting and to a great extent contradictory. This study compares the photodegradation of four substrates with diversified structures, namely, atrazine, fenitrothion, 4-chlorophenol (4-ClPh), and 2,4-dichlorophenoxyacetic acid (2,4-D) by both PW12O403− and TiO2 and how their photodegradation is affected by the presence of strong OH radical scavengers, i.e., Br− and isopropyl alcohol (i-prOH). The results provide substantial evidence that the literature data on the apparent photooxidation mechanism of these two categories of photocatalysts is circumstantial, depending on substrate and the mode of investigation. Overall, though, the action of OH radicals relative to h+ appears to be more pronounced with PW12O403− than TiO2. With respect to thermal (dark) reaction of photoreduced catalysts, both systems can deliver their electrons to a variety of oxidants including metal ions. The advantages of POM relative to TiO2 relates to the selective reduction precipitation of metal ions and to their unique ability to form metal nanoparticles in which POM serve both as reducing reagents and stabilizers.

Various polyoxometallates (POM) PW12O403−, SiW12O404−, P2W18O626− and P2Mo18O626− have been used as photocatalysts for the reductive destruction of the azo dye naphthol blue black (NB). In the process POM absorb light and mediate the electron transfer from a sacrificial donor, propan-2-ol, to the azo dye. NB is rapidly destructed in the presence of POM, while toxic intermediate products, such as aromatic amine derivatives (aniline, p-nitro-aniline and p-phenylene-diamine) are observed in a multi-electron process. Increase of catalyst and/or propan-2-ol concentration accelerates the photodegradation of dye till a saturation value, while an optimum concentration of the added dye is required. The nature of the POM catalyst dictates the efficiency of the reductive decoloration of NB, following the order PW12O403− > SiW12O404− > P2W18O626− according to their photooxidizing ability. No reaction is noticed with the 2-e-reduced molybdate, P2Mo18O628−, which exhibits a more positive redox potential.

Introduction: The aim of this study was to quantitatively characterize the bisphenol-A (BPA) released from orthodontic adhesives after artificial accelerated aging. Methods: A chemically cured, no-mix adhesive and a visible light-cured adhesive were bonded to 40 stainless steel brackets divided in 2 groups of 20 brackets each. In total, 3 series of specimens were prepared for each adhesive-bracket group. All specimens were immersed in alcohol to induce accelerated aging. Samples of eluent removed from each group at 1 day and at 1, 3, and 5 weeks after aging were processed with high-pressure liquid chromatography; all assays were performed in triplicate, and the results were averaged. Results: No trace of BPA was identified for either adhesive across all time intervals, implying that, if present, the amount of BPA did not exceed the detection limit of the analytical technique (0.1 ppm or 0.1 μg/L). Conclusions: BPA release from light-cured or chemically cured, no-mix adhesives did not reach the 0.1 ppm level. Estrogenicity assays are required to clarify the potential estrogenicity of adhesives, whereas formulation of benzoic ring-free, high molecular weight monomers might eliminate the concerns associated with the use of Bis-GMA.

Parallel experiments under similar conditions, using various substrates (atrazine, fenitrothion, 4-chlorophenol and 2,4-D) and OH radical scavengers (Br − , isopropyl alcohol, tertiary butyl alcohol and acetone), have shown that the photooxidizing mode of PW 12 O 40 3− and TiO 2 , i.e., OH radicals and/or holes (h + ), depends on the nature of substrate and the mode of investigation. This provides an explanation for the controversial results reported in the literature. Atrazine shows that both PW 12 O 40 3− and TiO 2 operate, mainly, via OH radicals and to a lesser extent with holes (h + ), whereas, fenitrothion suggests that both systems operate almost exclusively, via OH radicals. Differences in the action of the catalysts are encountered in the photodegradation of 4-chlorophenol (4-ClPh) and 2,4-dichlorophenoxyacetic acid (2,4-D). PW 12 O 40 3− appears to operate essentially via OH radicals, whereas, h + appear to be the major oxidant with TiO 2 . Overall, though, the action of OH radicals relative to h + appears to be more pronounced with PW 12 O 40 3− than TiO 2 .