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Andrea Nuzzo, Baharak Hosseinkhani, Nico Boon, Giulio Zanaroli, Fabio Fava
Biogenic palladium nanoparticles (bio-Pd NPs) represent a promising catalyst for organohalide remediation in water and sediments. However, the available information regarding their possible impact in case of release into the environment, particularly on the environmental microbiota, is limited. In this study the toxicity of bio-Pd NPs on the model marine bacterium V. fischeri was assessed. The impacts of different concentrations of bio-Pd NPs on the respiratory metabolisms (i.e. organohalide respiration, sulfate reduction and methanogenesis) and the structure of a PCB-dechlorinating microbial community enriched form a marine sediment were also investigated in microcosms mimicking the actual sampling site conditions...
November 25, 2016: Environmental Pollution
Filiz Karakas, Ipek Imamoglu
This study aims to estimate anaerobic dechlorination rate constants (km) of reactions of individual PCB congeners using data from four laboratory microcosms set up using sediment from Baltimore Harbor. Pathway km values are estimated by modifying a previously developed model as Anaerobic Dehalogenation Model (ADM) which can be applied to any halogenated hydrophobic organic (HOC). Improvements such as handling multiple dechlorination activities (DAs) and co-elution of congeners, incorporating constraints, using new goodness of fit evaluation led to an increase in accuracy, speed and flexibility of ADM...
November 9, 2016: Journal of Hazardous Materials
Mine Senyildiz, Buket Alpertunga, Sibel Ozden
3-Monochloropropane-1,2-diol (3-MCPD) is a well-known food processing contaminant that has been regarded as a rat carcinogen, which is known to induce Leydig-cell and mammary gland tumors in males, as well as kidney tumors in both genders. 3-MCPD is highly suspected to be a non-genotoxic carcinogen. 2,3-Epoxy-1-propanol (glycidol) can be formed via dehalogenation from 3-MCPD. We aimed to investigate the cytotoxic effects of 3-MCPD and glycidol, then to demonstrate the possible epigenetic mechanisms with global and gene-specific DNA methylation in rat kidney epithelial cells (NRK-52E)...
November 24, 2016: Drug and Chemical Toxicology
Stanislav Anatolievich Pshenichnyuk, Alberto Modelli, Eleonora F Lazneva, Alexei S Komolov
This study is aimed to point out the important role played by resonance electron attachment in reductive dehalogenation, in particular in phytoremediation of organic pollutants under conditions of excess negative charge. To model enzymatic reactions occurring in reductive conditions, low-energy electron capture by the halogenated herbicides atrazine and bromoxynil was studied in vacuo using electron transmission spectroscopy. A variety of decay channels of the temporary molecular negative ions was discovered by means of dissociative electron attachment spectroscopy...
November 4, 2016: Journal of Physical Chemistry. B
Katarzyna Wińska, Małgorzata Grabarczyk, Wanda Mączka, Barbara Żarowska, Gabriela Maciejewska, Katarzyna Dancewicz, Beata Gabryś, Antoni Szumny, Mirosław Anioł
The aim of this study was the chemical synthesis of a series of halo- and unsaturated lactones, as well as their microbial transformation products. Finally some of their biological activities were assessed. Three bicyclic halolactones with a methyl group in the cyclohexane ring were obtained from the corresponding γ,δ-unsaturated ester during a two-step synthesis. These lactones were subjected to screening biotransformation using twenty two fungal strains. These strains were tested on their ability to transform halolactones into new hydroxylactones...
October 31, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Alain Gamal Giuglio-Tonolo, Thierry Terme, Patrice Vanelle
We report here a novel and easy-to-handle reductive dehalogenation of 9-bromofluorene in the presence of arylaldehydes and dicarbonyl derivatives to give the corresponding fluorenyl alcohol derivatives and Darzens epoxides as by-products in tetrakis(dimethylamino)ethylene (TDAE) reaction conditions. The reaction is believed to proceed via two successive single electron transfers to generate the fluorenyl anion which was able to react with different electrophiles. A mechanistic study was conducted to understand the formation of the epoxide derivatives...
October 24, 2016: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
I Lengyel, F Toth, D Biyashev, I Szatmari, K Monory, C Tomboly, G Toth, S Benyhe, A Borsodi
Endomorphins are natural amidated opioid tetrapeptides with the following structure: Tyr-Pro-Trp-Phe-NH2 (endomorphin-1), and Tyr-Pro-Phe-Phe-NH2 (endomorphin-2). Endomorphins interact selectively with the μ-opioid or MOP receptors and exhibit nanomolar or sub-nanomolar receptor binding affinities, therefore they suggested to be endogenous agonists for the μ-opioid receptors. Endomorphins mediate a number of characteristic opioid effects, such as antinociception, however there are several physiological functions in which endomorphins appear to act in a fashion that does not involve binding to and activation of the μ-opioid receptor...
August 2016: Journal of Physiology and Pharmacology: An Official Journal of the Polish Physiological Society
Sunday A Adebusoye
Cupriavidus sp. strain SK-3, previously isolated on polychlorinated biphenyl mixtures, was found to aerobically utilize a wide spectrum of substituted aromatic compounds including 4-fluoro-, 4-chloro- and 4-bromobenzoic acids as a sole carbon and energy source. Other chlorobenzoic acid (CBA) congeners such as 2-, 3-, 2,3-, 2,5-, 3,4- and 3,5-CBA were all rapidly transformed to respective chlorocatechols (CCs). Under aerobic conditions, strain SK-3 grew readily on 4-CBA to a maximum concentration of 5 mM above which growth became impaired and yielded no biomass...
October 20, 2016: Biodegradation
Shanquan Wang, Siyuan Chen, Yu Wang, Adrian Low, Qihong Lu, Rongliang Qiu
Due to massive production and improper handling, organohalide compounds are widely distributed in subsurface environments, primarily in anoxic groundwater, soil and sediment. Compared to traditional pump-and-treat or dredging-and-disposal treatments, in situ remediation employing abiotic or biotic reductive dehalogenation represents a sustainable and economic solution for the removal of organohalide pollutants. Both nanoscale zero-valent iron (nZVI) and organohalide-respiring bacteria remove halogens through reductive dehalogenation and have been extensively studied and successfully applied for the in situ remediation of chloroethenes and other organohalide pollutants...
October 17, 2016: Biotechnology Advances
Valeria Ochoa-Herrera, Jim A Field, Antonia Luna-Velasco, Reyes Sierra-Alvarez
Perfluorooctane sulfonate (PFOS) and related perfluoroalkyl and polyfluoroalkyl substances (PFASs) are emerging contaminants that have been widely applied in consumer and industrial applications for decades. However, PFOS has raised public concern due to its high bioaccumulative character, environmental persistence, and toxicity. Shorter PFASs such as perfluorobutane sulfonate (PFBS) and polyfluoroalkyl compounds have been proposed as alternatives to PFOS but it is unclear whether these fluorinated substances pose a risk for public health and the environment...
September 14, 2016: Environmental Science. Processes & Impacts
L Szatkowski, M B Hall
The nickel(i) octaethylisobacteriochlorin anion ([OEiBCh-Ni((I))](-)) is commonly used as a synthetic model of cofactor F430 from Methyl-Coenzyme M Reductase. In this regard, experimental studies show that [OEiBCh-Ni((I))](-) can catalyze dehalogenation of aliphatic halides in DMF solution by a highly efficient SN2 reaction. To better understand this process, we constructed theoretical models of the dehalogenation of chloromethane by a simple nickel(i) isobacteriochlorin anion and compared its reactivity with that of similar Ni((I)) complexes with other porphyrin-derived ligands: porphyrin, chlorin, bactreriochlorin, hexahydroporphyrin and octahydroporphyrin...
September 28, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Xinlin Li, Shiling Zhao, Wei Zhang, Yansheng Liu, Rong Li
Ruthenium (Ru) nanoparticles (NPs) are supported on nitrogen-doped porous carbon (NPC) derived from metal-organic-framework (MOF) ZIF-8 for the first time. NPC is prepared by the direct carbonization of ZIF-8 crystals, which not only retains the original morphology of ZIF-8 but also provides a high surface area and stable chemical-physical properties. Ru NPs were supported by different methods. Four types of Ru-based catalysts are tested in the selective hydrogenation of p-chloronitrobenzene (p-CNB) and p-bromonitrobenzene (p-BNB) to haloanilines...
October 4, 2016: Dalton Transactions: An International Journal of Inorganic Chemistry
Feng-Cheng Jia, Cheng Xu, Zhi-Wen Zhou, Qun Cai, Yan-Dong Wu, An-Xin Wu
An unusual benzannulation reaction has been realized by integrating intermolecular adol condensation with subsequent intramolercular base-promoted homolytic aromatic substitution. This novel cascade reaction provides a straightforward approach toward various naphtho-fused oxindoles from 2-halobenzaldehydes and indolin-2-ones in the presence of Cs2CO3 in DMSO. The enolates of indolin-2-ones as new and internal electron donors have been demonstrated to initiate intramolecular radical dehalogenative coupling.
October 4, 2016: Organic Letters
Abrahim El Gamal, Vinayak Agarwal, Imran Rahman, Bradley S Moore
Enzymes capable of performing dehalogenating reactions have attracted tremendous contemporary attention due to their potential application in the bioremediation of anthropogenic polyhalogenated persistent organic pollutants. Nature, in particular the marine environment, is also a prolific source of polyhalogenated organic natural products. The study of the biosynthesis of these natural products has furnished a diverse array of halogenation biocatalysts, but thus far no examples of dehalogenating enzymes have been reported from a secondary metabolic pathway...
October 12, 2016: Journal of the American Chemical Society
Yu Zhang, Jeffrey L Petersen, Carsten Milsmann
Titanium and zirconium complexes carrying two 2,6-bis(pyrrolyl)pyridine ligands have been synthesized and characterized. The neutral complexes Ti((Me)PDP)2 and Zr((Me)PDP)2 ((Me)PDP = 2,6-bis(5-methyl-3-phenyl-1H-pyrrol-2-yl)pyridine) show intense ligand-to-metal charge-transfer bands in the visible region and undergo multiple reversible redox events under highly reducing conditions. Zr((Me)PDP)2 exhibits photoluminescent behavior and its excited state can be quenched by mild reductants to generate a powerful electron transfer reagent with a ground state potential of -2...
October 12, 2016: Journal of the American Chemical Society
Abhishek Phatarphekar, Steven E Rokita
The flavoprotein iodotyrosine deiodinase (IYD) was first discovered in mammals through its ability to salvage iodide from mono- and diiodotyrosine, the by-products of thyroid hormone synthesis. Genomic information indicates that invertebrates contain homologous enzymes although their iodide requirements are unknown. The catalytic domain of IYD from Drosophila melanogaster has now been cloned, expressed and characterized to determine the scope of its potential catalytic function as a model for organisms that are not associated with thyroid hormone production...
December 2016: Protein Science: a Publication of the Protein Society
Peter H Jacobse, Adri van den Hoogenband, Marc-Etienne Moret, Robertus J M Klein Gebbink, Ingmar Swart
The Ullmann coupling has been used extensively as a synthetic tool for the formation of C-C bonds on surfaces. Thus far, most syntheses made use of aryl bromides or aryl iodides. We investigated the applicability of an aryl chloride in the bottom-up assembly of graphene nanoribbons. Specifically, the reactions of 10,10'-dichloro-9,9'-bianthryl (DCBA) on Au(111) were studied. Using atomic resolution non-contact AFM, the structure of various coupling products and intermediates were resolved, allowing us to reveal the important role of the geometry of the intermediate aryl radicals in the formation mechanism...
October 10, 2016: Angewandte Chemie
Haiming Zhang, Lifeng Chi
Gold-organic hybrids can be prepared on gold substrates by on-surface dehalogenation of molecular precursors with multiple halogen substituents. Various contact geometries of covalent arylAu bonds are achieved by changing the halogen substituents in the bay or peri regions. Scanning tunneling microscopy/spectroscopy (STM/STS) investigations allow a better understanding of the structure/property relationships in various gold-aryl contacts. Recent progress on the synthesis, large-scale alignment, and STS measurement of gold-organic hybrids is described, ending with an emphasis on potential future applications, e...
September 15, 2016: Advanced Materials
Ian D Wilson, Jeremy K Nicholson
The gut microbiota has both direct and indirect effects on drug and xenobiotic metabolisms, and this can have consequences for both efficacy and toxicity. Indeed, microbiome-driven drug metabolism is essential for the activation of certain prodrugs, for example, azo drugs such as prontosil and neoprontosil resulting in the release of sulfanilamide. In addition to providing a major source of reductive metabolizing capability, the gut microbiota provides a suite of additional reactions including acetylation/deacylation, decarboxylation, dehydroxylation, demethylation, dehalogenation, and importantly, in the context of certain types of drug-related toxicity, conjugates hydrolysis reactions...
August 13, 2016: Translational Research: the Journal of Laboratory and Clinical Medicine
Xianbin Su, Ruihong Li, Jimmy S H Tsang
Biodegradation is an effective way to remove environmental pollutants haloacids, and haloacids uptake is an important step besides cytoplasmic dehalogenation. Previous study has identified a robust haloacids transport system in Burkholderia caribensis MBA4 with two homologous genes deh4p and dehp2 as major players. Both genes are inducible by monochloroacetate (MCA), and dehp2 is conserved among the Burkholderia genus with a two component system upstream. Here we show that dehp2 is not in the same operon with the upstream two component system, and fusion with lacZ confirmed the presence of MCA-inducible promoter activity in the 228bp upstream non-coding region of dehp2...
November 30, 2016: Gene
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