Poly Brominated Diphenyl Ethers (PBDEs) are known flame retardants with highly persistent and lipophilic in nature. The continued usage of PBDE in various products amplifies the human burden of PBDEs. It is therefore, important to study the potential toxicological and/or biological effects of PBDE exposure in human. In this study we investigated the mode of action of PBDE induced toxicity in human liver by exposing human hepatocarcinoma cells in a time (24-72h) and dose (0-100μM) dependent manner. The highest test dose caused an inhibition in cell viability up to 50% after 72h, whereas lower doses (<50μM) showed slight increase in cell viability. Likewise, higher doses caused significant accumulation of intracellular ROS over time. Further, increase in caspase-3 enzyme levels and DNA fragmentation showed that, lower brominated PBDEs induce liver toxicity through accumulation of toxic metabolites and reactive oxygen species over time leading to caspase-mediated apoptotic cell death.

Nitrogen-containing heterocyclic compounds are very important to the pharmaceutical and agrochemical industries, among others. Over the past few years, the Beauchemin group has been exploring reactivity of N-substituted isocyanates and as part of this has developed a metal-free alkene aminocarbonylation process relying on imino-isocyanates to form azomethine imines. The azomethine imines formed are interesting since they contain a cyclic β-aminocarbonyl motif. Catalysis of this reaction using basic additives allowed milder reaction conditions with electron-rich C=C bonds such as enol ethers. Efforts have also been made towards the derivatization of these azomethine imines into useful products. It was discovered that upon reduction and aromatization of azomethine imines, pyrazolones could be obtained. This is providing a novel modular approach to these compounds, which have relevance in pharmaceuticals and agrochemicals. This reactivity was extended to include imino-isothiocyanates.

No description available.

Polybrominated diphenyl ethers belong among the persistent compounds, which have been classified as priority organic pollutants. In environmental compartments are observed in the past decade. Polybrominated diphenyl ethers are detected in abiotic and biotic matrices. For this dissertation were chosen the matrixes from seats of fire, taken in various localities of the Czech Republic and Slovakia. Their analysis should demonstrate whether they in these specific matrices remain. There were examined following polybrominated diphenyl ether congeners: BDE- 28, 47, 99, 100, 153, 154, 183. For their isolation from the matrix were used three different extraction techniques, namely ultrasonic extraction, microwave extraction and pressurized solvent extraction. For the determination was chosen method of GC / ECD. In this dissertation are also described basic chemical, physical and environmental properties of BDE, including other analytical methods that can be used to determine polybrominated diphenyl ethers in environmental compartments.

Neuartige Cellulosederivate werden ausgehend von kommerziellen Celluloseethern synthetisiert. Aufgrund der guten Löslichkeit der Celluloseether in polaren Lösungsmitteln erfolgt eine homogene Reaktionsführung, wodurch eine regelmäßige Verteilung der Sulfatgruppen entlang der Polymerkette gewährleistet wird. Durch Variation der Reaktionsparameter wie Sulfatierungsmittel, Lösungsmittel, Reaktionszeit und -temperatur erfolgte die Synthese zahlreicher Celluloseethersulfate mit unterschiedlichen Eigenschaften bezüglich Sulfatierungsgrad und kinematischer Viskosität. Durch Bestimmung des Schwefelgehaltes und entsprechender Berechnungen konnten die Anzahl der Sulfatgruppen im Molekül (DSSul) ermittelt werden, wobei die Werte für die synthetisierten Proben im Bereich zwischen DSSul = 0.1 bis DSSul = 2.7 lagen. Der Abbau der Polymerkette wurde ebenfalls durch die Reaktionsbedingungen gesteuert, sodass sowohl Produkte mit hohen (1698 mm2/s) als auch sehr niedrigen (2 mm2/s) kinemtischen Viskositäten resultierten. Wasserlöslichkeit der Produkte wurde durch Trübungsmessungen von 1%igen wässrige Lösungen und der daraus erhaltenen geringen Trübungswerte (NTU < 10) ermittelt. Die Funktionalisierung der Celluloseether mit Sulfatgruppen konnte mittels spektroskopischer Methoden nachgewiesen werden. In 13C-NMR-Spektren von Hydroxypropylcellulosesulfaten wurden zusammen-hängende strukturelle Veränderungen mit dem Anstieg des DSSul der Produkte korreliert. Durch charakteristische Signale im Bereich der Ether-Kohlenstoffatome und deren Verschiebung wurde belegt, dass die Sulfatierung des Celluloseethers an den freien Hydroxylgruppen der Etherseitenkette erfolgte. Mittels FT-RAMAN-Spektroskopie konnten für Sulfatgruppen charakteristische Banden der in den Spektren der sulfatierten Celluloseether nachgewiesen und zugeordnet werden. Aufgrund der ionischen Sulfatgruppen dissoziieren die Celluloseethersulfate in Wasser in geladene Polymerketten. Dadurch ist in Gegenwart von kationischen Polyelektrolyten (polyDADMAC) die Bildung von Polyelektrolytkomplexen in Form von Kapseln und Folien/Membranen möglich. Die Fähigkeit solcher Polyelektrolytkapseln aus Celluloseethersulat und polyDADMAC zu Verkapselung von Substanzen und deren anschließende Freisetzung wurde am Beispiel der Verkapselung des Fluoreszenzfarbstoffes Rhodamin B gezeigt. Mittels fluoreszenzspektroskopischer Messungen konnte der aus den Kapseln freiwerdende Farbstoff detektiert werden. Anhand der Messungen wurde gezeigt, dass die Farbstofffreigabe im Fall von Rhodamin B abhängig von den Probeneigenschaften ist. Durch die Wahl des Ausgangsstoffes und deren Funktionalisierung mit Sulfatgruppen kann die Farbstofffreisetzung gesteuert werden. Mit zunehmendem DSSul des Celluloseethersulfates verlängert sich die Verweilzeit des Fluoreszenz-farbstoffes in der Kapsel. Zusätzliche Funktionelle Gruppen in der Seitenkette des Ausgangsstoffes führen zu sterischen Hinderung bei der Wechselwirkung mit polyDADMAC, wodurch eine gegenseitige Durchdringung der Polymerketten bei der Ausbildung des Polyelektrolytkomplexes gehindert wird, sodass weniger kompakte Membranstrukturen der Kapseln resultieren. In Zellexperimente mit adhärenten Zelllinien an entsprechenden mit Celluloseethersulfat präpartierten Oberflächen wurde gezeigt, dass die Zelladhäsion durch den Sulfatierungsgrad der Proben beeinflusst wird. Auf Proben mit höherem Sulfatierungsgrad findet eine verbesserte Adhäsion im Vergleich zu Proben statt, die einen geringen Sulfatierungsgrad aufweisen. Demnach wird die Kompatibilität der Zellen auf solche Oberflächen durch die Erhöhung des Substitutionsgrades der Proben begünstigt.

We also investigated whether BDE-47 exposure could worsen PD situation by applying transgenic Drosophila (fly) model in which human α-synuclein (α-syn) was overexpressed in wide-type fly to simulate PD. BDE-47 (0, 2, 10 and 50 µM) was fed to flies continuously for 30 days. Integrated LC-MS and GC-MS profiling indicated metabolic changes in tryptophan, phenylalanine, purine, and alanine, aspartate and glutamate pathways, similar to those from mouse experiment. After quantified metabolites of interest by LC-triple quadrupole MS, we confirmed the slowed-down formation of KYNA (kynurenic acid, a neuro-protector) and speeded-up formation of 3HKYN (3-hydroxykynurenine, a neurotoxin) in all BDE-47 exposed groups on the 20th exposure day. The levels of SAM/SAH (methylation biomarker) and GSH/GSSG (oxidative stress biomarker) were found to decrease on the 30th exposure day. Collectively, we propose that BDE-47 could induce imbalance of kynurenine metabolism, insufficient methylation and oxidative stress, which might contribute to the PD progression. To further explore the underlying mechanism of 6-OH-BDE-47 induced neurotoxicity, we conducted omics study of metabolic changes induced by 6-OH-BDE-47 on N2a cells. Cells were exposed to 6-OH-BDE-47 (0, 0.5 and 1 μM) for 24 hours. Considerable metabolic changes in pyrimidine and purine metabolism were observed in high exposure condition while oxidative stress was appeared under low exposure condition. Moreover, 6-OH-BDE-47 was found to affect the dopamine production. iTRAQ proteomics was carried out and pinpointed the dysregulation of ribosome, proteasome, RNA metabolism, aminoacyl-tRNA biosynthesis, vesicular trafficking, purine pathway, and mitochondria electron transport. Immunocytochemistry and Western blot analysis further confirmed that 6-OH-BDE-47 could inhibit autophagy flux, which might result in the aberrant protein aggregation, a pathological hallmark of PD. We further investigated whether 6-OH-BDE-47 exposure could directly induce PD pathology in Sprague Dawley rat. 6-OH-BDE-47 (0.1, 1 and 10 µg) was stereotaxically injected into the right VTA and SNc regions in the midbrain of rat where there are abundant dopaminergic neurons. The apomorphine-induced rotation test indicated significant deterioration in motor function in the group receiving injection of 10 µg. Striatal dopamine was found to decline in a dose-dependent manner. Notably, 6-OH-BDE-47 also promoted the formation of α-syn aggregate, an important pathological hallmark of PD. Proteomics study revealed that protein degradation processes were crucial rather than oxidative stress in 6-OH-BDE-47 induced neurotoxicity in vivo. Mechanistic study based on Western blot further confirmed that 6-OH-BDE-47 could inhibit ubiquitination and autophagy. Collectively, the rat experiment demonstrated that 6-OH-BDE-47 administration could induce motor defect by impairing dopaminergic system and promote α-syn aggregation by inhibiting ubiquitination and autophagy, suggesting that 6-OH-BDE-47 could be a novel risk factor of PD.;Polybrominated diphenyl ethers (PBDEs), as one typical persistent organic pollutants (POPs), are widely spread in the environment and pose potential adverse impacts on human health. As a predominant congener of PBDEs, 2,2',4,4'-tetrabromodiphenyl ether (BDE-47) has been reported to affect habituation capability, synaptic plasticity, and vesicular neurotransmitter release. As an important in vivo metabolite derived from BDE-47, 6-hydroxy-BDE-47 (6-OH-BDE-47) was also reported as a neurotoxin. However, the possible linkages between BDE-47/6-OH-BDE-47 exposure and typical neurodegenerative diseases such as Parkinson's disease (PD) are still unclear. Mass spectrometry (MS) based omics integrated with bioinformatics is emerging as a powerful tool to evaluate metabolic changes occurred after different exposures. Here we developed non-targeted metabolomics, lipidomics, and isobaric tag for relative and absolute quantitation (iTRAQ) proteomics methods based on liquid chromatography-mass spectrometry (LC-MS) and gas chromatography-mass spectrometry (GC-MS) to depict BDE-47/6-OH-BDE-47 induced metabolic changes and to explore the possible contribution of their exposure to PD pathology/pathogenesis. BDE-47 dissolved in corn oil (0, 1, 10 and 100 mg/kg bwt) was orally administered to adult male C57BL/6 mice for 30 consecutive days. Results of global metabolomics and lipidomics studies of PD-related brain regions based on LC-orbitrap MS revealed significant metabolite changes between the exposed and control groups in purine pathway, glutathione pathway, tryptophan pathway, phenylalanine pathway, alanine, aspartate and glutamate pathway, and lipid composition, mainly involved in oxidative stress and neurotransmitter production. By further quantifying metabolites involved in tryptophan and phenylalanine pathways in mice serum, colon and brain samples by using LC-triple quadrupole MS, dysregulation of PD linked neurotransmitters dopamine and serotonin were confirmed. iTRAQ proteomics study of the striatum, the part of the brain that is most intensively studied in PD pathogenesis, revealed that BDE-47 could induce neurotransmitter system disturbance, mitochondrial dysfunction, oxidative stress and abnormal phosphorylation. Oxygen consumption rate after BDE-47 treatment (0, 1 and 10 μM) in mouse neuroblastoma (N2a) cells was measured for the confirmation. BDE-47 was demonstrated to impair mitochondrial function.

No description available.

No description available.

Flame retardants (FRs) are widely used in a variety of consumer products, including electronics, textiles, vehicles, furniture foams, and children’s toys. Many of these chemicals are halogenated compounds that are persistent in the environment over long periods of time and are known or suspected endocrine disruptors. As a result, FRs may have a variety of negative health effects on humans and wildlife. Following the discontinuation of commercial polybrominated diphenyl ether (PBDE) mixtures, a variety of alternative FRs have been developed and employed. In comparison with legacy FRs, relatively little is known about the ability of these emerging FRs to bioaccumulate and biomagnify in various systems. The primary objective of my dissertation was to better understand the contamination status of both legacy and emerging FR in the biota of the northwestern Atlantic Specifically my objectives were to (1) identify and quantify legacy and emerging FRs in high trophic level predator species (sharks) of the northwestern Atlantic, (2) determine Tropic Magnification Factors (TMFs) for legacy and emerging FRs within the same food web, and (3) evaluate the maternal transfer of a variety of brominated and chlorinated FRs in viviparous Atlantic sharks.

The purpose of this investigation is to examine reactions of anions of oximes, oxime ethers and imines with acylating agents and other electrophiles. It is also an attempt to utilize the phenomenon of geometrical enantiomeric isomerism, in which absolute configuration is determined by double bond geometry, and the concept of regiospecific anion formation, also determined by double bond geometry, for stereospecific synthesis of tropinone derivatives.