Donepezil is a centrally acting acetylcholinesterase (AChE) inhibitor with therapeutic potential in inflammatory diseases; however, the underlying autonomic and cholinergic mechanisms remain unclear. Here, we assessed effects of donepezil on mean arterial pressure (MAP), heart rate (HR), HR variability, and body temperature in conscious adult male C57BL/6 mice to investigate the autonomic pathways involved. Central versus peripheral cholinergic effects of donepezil were assessed using pharmacological approaches including comparison with the peripherally acting AChE inhibitor, neostigmine. Drug treatments included donepezil (2.5 or 5 mg/kg sc), neostigmine methyl sulfate (80 or 240 μg/kg ip), atropine sulfate (5 mg/kg ip), atropine methyl bromide (5 mg/ kg ip), or saline. Donepezil, at 2.5 and 5 mg/kg, decreased HR by 36 ± 4% and 44 ± 3% compared with saline (n = 10, P < 0.001). Donepezil, at 2.5 and 5 mg/kg, decreased temperature by 13 ± 2% and 22 ± 2% compared with saline (n = 6, P < 0.001). Modest (P < 0.001) increases in MAP were observed with donepezil after peak bradycardia occurred. Atropine sulfate and atropine methyl bromide blocked bradycardic responses to donepezil, but only atropine sulfate attenuated hypothermia. The pressor response to donepezil was similar in mice coadministered atropine sulfate; however, coadministration of atropine methyl bromide potentiated the increase in MAP. Neostigmine did not alter HR or temperature, but did result in early increases in MAP. Despite the marked bradycardia, donepezil did not increase normalized high-frequency HR variability. We conclude that donepezil causes marked bradycardia and hypothermia in conscious mice via the activation of muscarinic receptors while concurrently increasing MAP via autonomic and cholinergic pathways that remain to be elucidated.

Malaria (vector: Anopheles gambiae) is a major infectious disease that kills about 1 million people each year. For the improvement of its treatment and vector control during the past decades, several issues such as high medicine cost, insecticide resistance, and lack of an effective vaccine have prevented adequate control of malaria. Additionally, the low selectivity of malaria vector insecticides also presents a public health problem. The purpose of developing novel carbamate insecticides in our laboratory is to offer effective and selective insecticide options to achieve the ultimate goal of malaria control. First, 50% inhibition concentration (IC50) data was collected from three mammalian AChEs with eight commercial carbamate insecticides by using the Ellman assay. The IC50 values varied from 57 nM to 7358 nM. The AChE sensitivity pattern and level were shown to be similar between the recombinant mouse and ICR male mouse brain cortex homogenate (slope = 0.99, R2 = 0.96). Then eight novel carbamate insecticides that are possible malaria vector control agents were selected for further neurotoxicity testing in non-target organisms. For commercial carbamate insecticides, the IC50 varied from 9.1 nM to 2,094 nM. For the novel carbamate insecticides, it varied from 58 nM to 388,800 nM. Based on IC50 data from previous work on A. gambiae, the selectivity index (IC50 of non-target species / IC50 A. gambiae) ranged from 0.17 to 5.64 and from 0.47 to 19,587 for commercial and novel carbamate insecticides, respectively. Subsequently, the AChE protein sequence alignment comparison and cladogram were used to compare the genetic and evolutionary relationship among five different organisms. The alignment score ranged from 88 for mouse vs. human to 54 for hen vs. T. californica. The evolutionary relationships among species was obtained from the cladogram. Recombinant mouse vs. recombinant human was shown to have the most similar inhibitor potency profiles (alignment score = 88, closest taxa position on cladogram, similar AChE sensitivity pattern [R2 = 0.81] and level [P > 0.05] to the novel carbamates). Neurotoxic esterase (NTE) assay showed that the novel carbamates did not significantly inhibit NTE, inhibition of which underlies a significant hazard for anticholinesterases, especially organophosphates, in several nontarget vertebrate organisms. The NTE activity in the presence of novel carbamate insecticides ranged from 93% to 116% of the control, while in the commercial group, bendiocarb significantly inhibited NTE, leaving only 76.5% of the initial reactivity at 1 mM inhibitor concentration. Further in vivo bioassay using Daphnia magna was conducted to compare the aquatic toxicity of commercial and novel carbamates. The data showed that except for PRC331 (3-tert-butylphenylmethylcarbamate), all novel carbamates were of similar potency as bendiocarb (LC50 = 611 nM) for aquatic toxicity, and their LC50 values ranged from 172 nM (PRC331) to 1109 nM. In conclusion, the novel carbamate insecticides would appear to be an improvement over commercial carbamate insecticides because of greater selectivity, negligible NTE inhibition capacity, but in some cases with potent in vivo toxicity to Daphnia magna. However, since the envisioned usage of these compounds is in bednets or as indoor residual sprays (IRS), any environmental exposures to nontarget aquatic organisms are expected to be minimal. / Master of Science

Alzheimer's Disease (AD) is an irreversible, age-related neurodegenerative disorder which causes cognitive impairment and a wide variety of neuropsychiatric and behavioral disturbances. Acetylcholinesterase inhibitors (AChEI) are the mainstay for the treatment of AD. Acetylcholinesterase (AChE) catalyzes the hydrolysis of acylcholinesters with a relative specificity for acetylcholine (ACh). Observation of a deficiency of cholinergic neurotransmission in AD led to the development of AChEI as the first approved treatment for dementia symptoms. Tacrine (9-amino-1,2,3,4-tetrahydroacridine) is a reversible inhibitor of AChE. It was the first drug approved by the FDA for the treatment of cognitive symptoms of AD. Tacrine is now rarely prescribed as a drug for the treatment of AD due to its high hepatotoxicity in almost 50% of the patients. However, tacrine derivatives have considerable potential for the palliative treatment of AD. Synthesis of various bivalent tacrines led to the improvement in inhibitory potency and selectivity towards inhibition of AChE. Heptylene-linked bis-tacrine has especially shown immense promise to be an ideal AChEI. Thus dimerization of a lead compound seemed to be an ideal strategy where the compound can bind to both catalytic anionic site (CAS) and peripheral anionic site (PAS) on the AChE enzyme. However synthesis of N-alkyl derivatives of expanded tacrines like 12-chloro-2-methyl-6,7,8,9,10,11-hexahydrocycloocta[b]quinoline by the standard SNAr methods was unsuccessful and thus alternatives needed to be developed to synthesize N-alkylated and bivalent 12-chloro-2-methyl-6,7,8,9,10,11-hexahydrocycloocta[b]quinoline. Upon exploring the alternatives, N-arylation by Pd-catalysis seemed to be the most mild and convenient alternative over the standard SNAr procedures. / Master of Science

Pesticides are commonly used around the world for a multitude of different purposes and on diverse habitats, including agricultural fields, wetlands, and personal lawns and gardens. Currently, acetylcholinesterase (AChE)-inhibiting pesticides are among the most prevalently used chemical pesticides in the United States. A wealth of information exists on sub-cellular responses of organisms, primarily birds, mammals, and fish, exposed to these compounds. However, the effects of AChE-inhibiting pesticides at the whole-organism level, most importantly effects relevant to an individual's fitness, have received less attention. My Master's research focused on describing the effects of carbaryl, an AChE-inhibiting pesticide, on several fitness-related traits in the western fence lizard (Sceloporus occidentalis). Reptiles are the least studied vertebrate taxon in ecotoxicological studies even though contaminants are suspected in contributing to recent population declines. Using multiple dose concentrations within the range expected to occur in nature (based on EPA application rates and published pesticide residues on insects), I quantified the effects of carbaryl on sprint performance energy acquisition, and energy allocation, traits which could have important implications for the animal's ability to avoid predators, capture prey, and grow and reproduce. I found that at the highest dose concentration, lizards experienced a decrease in arboreal and terrestrial locomotor performance, a decrease in energy acquisition, and alterations in energy allocation. My findings suggest that acute exposure to high concentrations of carbaryl can have important sublethal consequences on fitness-related traits in S. occidentalis. Future studies should examine the consequences of multiple-pulse exposures to AChE-inhibiting pesticides on reptiles. / Master of Science

Adéla Dolejšová Testing the efficacy of potential therapeutics for Alzheimer,s disease Charles University in Prague, Faculty of Pharmacy in Hradec Kralove Pharmacy The aim of this thesis was to find out whether already implemented Ellman's method, which is used to analyse irreversible inhibitors AChE, is going to be a suitable technique for measuring reversible inhibitors. Furthermore, the efficiency of newly synthesized AChE inhibitors was established. These inhibitors will be used for treating AD or as prophylaxis against neural paralytic substances. Moreover, it was compared affect the efficacy of AChE inhibitors after intramuscular and intraperitoneal administration. The measurements were done in vivo on potkan species Wistar. In the first experiment standard AChE (tacrin, 7-MEOTA, donepezil, rivastigmin) inhibitors were applied to verify the method. In the second experiment the newly synthesizes AChE (K 298, K 344, K 474) inhibitors were medicine. The results confirmed the effectiveness of the tested method on commonly used inhibitors such as donepezil and rivastigmin. Out of the newly synthesized K 298, K 344 and K 474 inhibitors none was proven to have any significant inhibiting activity. Key words: acetylcholinesterase, acetylcholinesterase inhibitors, Alzheimer disease, cholinergic system,...

Este trabalho descreve a preparação, a caracterização e o uso de um biossensor de pasta de carbono modificado com a enzima acetilcolinesterase para a quantificação de carbamatos em alimentos, bem como o estudo das constantes de velocidade para a reação enzima/substrato (iodeto de acetiltiocolina) em solução. Inicialmente foram realizados testes de estabilidade, tanto para o substrato quanto para a enzima. Nestes testes, a absorção na região do UV-vis do substrato não apresentou diminuição significativa em 11 dias de análises, já a enzima apresentou uma grande perda de sua atividade com apenas três dias de preparo da solução. Na preparação do eletrodo de trabalho alguns parâmetros foram otimizados, tais como: quantidade de enzima e de ftalocianina de cobalto (CoPC) no eletrodo, bem como a porcentagem de glutaraldeído utilizada. A melhor resposta ocorreu para adição de 2,40x10-3g de enzima, 0,90x10-3g de CoPC (referentes à massa de 0,017g de pasta de carbono) e solução de glutaraldeido 1%. A seguir, realizou-se um experimento baseado na inibição da atividade da enzima, causada pela imersão do eletrodo na solução contendo o pesticida carbaril nas concentrações 5,00x10-5 e 1,00x10-4 mol L-1. Notou-se que, com o aumento da concentração do carbaril, houve aumento na inibição da atividade enzimática. Desta forma o eletrodo apresentou-se apto para determinação analítica de pesticidas. Estas medidas foram realizadas em meio de tampão fosfato 0,1 mol L-1, pH 7,4 e com tempo de incubação para o carbaril, metomil e aldicarbe foram de 8, 12 e 15 minutos, respectivamente. Os limites de detecção (LD) e quantificação (LQ) obtidos utilizando-se o biossensor amperométrico para o carbaril foram de 2,00x10-6 mol L-1 (0,40 mg L-1) e 6,70 x 10-6 mol L-1 (1,30 mg L-1), para o metomil de 1,88 x 10-7mol L-1 (30,45 micro g L-1) e 6,26 x 10-7 mol L-1 (0,10 mg / L-1) e para o aldicarbe de 1,10x10-6 mol L-1 (0,20 mg L-1) e 3,60x10-6 mol L-1 (0,70 mg L-1). Para a formulação comercial Lannate (metomil) os LD e LQ foram 2,13x10-7 mol L-1 (34,50 micro g L-1) e 7,09x10-7 mol L-1(0,12 mg L-1), respectivamente. As medidas de HPLC apresentaram LD e LQ de 1,58 x 10-8 mol L-1 (3,18 micro g L-1) e 5,27x10-8 mol L-1 (10,60 micro g L-1) para o carbaril e de 9,02 x 10-10 mol L-1 (0,15 micro g L-1) e 3,00 x 10-9 mol L-1 (48,60 micro g L-1) para o metomil. Testes de recuperação foram realizados usando ambas as técnicas para o carbaril e Lannate. As recuperações utilizando-se o biossensor mostraram-se eficientes, variando de 76,83 a 106,67% para o carbaril e de 78,00 a 96,50% para a Lannate, enquanto que nas medidas de HPLC, as recuperações foram de 78,00 a 108,33% para o carbaril e de 57,00 a 99,50% para o Lannate. A recuperação para o aldicarbe no tomate foi de 62,40 %. As análises da enzima em solução mostraram que a metodologia empregada neste estudo é adequada para a determinação das constantes de velocidade para a etapa lenta da reação AchE/AchI. Observou-se que os valores destas constantes são dependentes da concentração dos pesticidas fenitrothion (organofosforado) e carbaril (carbamato), em baixa concentração ambos apresentaram constantes de velocidade similares, mas com o aumento dessa concentração, o fenitrothion apresentou menor constante de velocidade em relação ao carbaril, sugerindo que este apresenta maior inibição da enzima e por conseqüência maior toxicidade no organismo. Esses resultados mostraram uma possível metodologia analítica para a quantificação destes pesticidas, obtendo-se os valores das constantes de velocidade enzimática e suas dependências com as concentrações dos pesticidas em solução. / This work describes the development, characterization and utilization of a carbon paste biosensor based in the acetylcholinesterase enzyme for carbamates determinations in foodstuff, as well as the study of rate constants for enzyme/substrate reaction in solution. Stability tests were initially performed for both the substrate and the enzyme. In these tests, the signal for UV-vis adsorption for the substrate shows no inhibition during 11 days while for the enzyme it has been demonstrated that a considerable loss of activity occurs after three days from the solution preparation. In the electrode preparation, some experimental parameters were optimized, such as the amount of enzyme and the content of cobalt ftalocyanine (CoPC) in the electrode, as well as the employed percentage of glutaraldehide. The highest analytical signals were obtained for the addition of 2.40x10-3 g enzyme, 0.90x10-3 g CoPC (related to the massa of 0,017g of carbon paste) and a 1% glutaraldehide solution. The next step was to carry out an experiment based in the inhibition of enzyme activity by the pesticide. For this, the biosensor was immersed in 5.00x10-5 e 1.00x10-4 mol L-1 carbaryl solutions. It was observed that, by increasing the carbaryl concentration, the electrochemical signal of the sensor was inhibited proportionally. This was indicative that the sensor was adequate to be used in carbaryl monitoring and analytical determinations. The analytical determinations of carbamate pesticides were performed in 0.1 mol L-1 phosphate buffer, pH 7,4, with incubation time of 8, 12 and 15 minutes for carbaryl, metomil and aldicarb, respectively. The detection (LD) and quantification (LQ) limits obtained with the biosensor were 2.00x10-6 mol L-1 (0.40 mg L-1) and 6.70 x 10-6 mol L-1 (1.30 mg L-1) for carbaryl, 1.88x10-7mol L-1 (30.45 micro g L-1) and 6.26x10-7 mol L-1 (0.10 mg / L-1) for metomil and 1.10x10-6 mol L-1 (0.20 mg L-1) and 3.60x10-6 mol L-1 (0.70 mg L-1) for aldicarb. For the commercial formulation of metomil, Lannate, LD and LQ obtained were 2.13x10-7 mol L-1 (34.50 microg L-1) and 7.09x10-7 mol L-1(0.12 mg L-1), respectively. The HPLC measurements showed LD and LQ of 1.58x10-8 mol L-1 (3.18micro g L-1) and 5.27x10-8 mol L-1 (10.60 micro g L-1) for carbaryl and 9.02x10-10 mol L-1 (0.15 micro g L-1) and 3.00x10-9 mol L-1 (48.60 micro g L-1) for metomil. Recovering tests were also done with both analytical techniques for carbaryl and Lannate. The obtained recoveries using the biosensor were in the range of 76.83 to 106.67% for carbaryl and 78.00 to 96.50% for Lannate, while using the HPLC, the recoverings were 78.00 a 108.33% for carbaryl and 57.00 to 99.50% for Lannate. The recovering of aldicarb in tomatoes, with HPLC, were 62.40 %. The study of the enzymatic reaction in solution showed that the employed methodology allows to obtain the rate constant values for the rate determining step of the AchE/AchI reaction. It was observed that these rate constant values were strongly dependent in the pesticide concentrations for fenitrothion (organofosforous) and carbaryl (carbamate). At low concentration levels of the pesticide in the electrolyte, all the rate constants showed similar values but, when the pesticide concentration was raised, fenitrothion was found to exert a more powerful inhibition action for the enzyme activity than carbaryl, thus suggesting its higher toxic character. These results showed the development of a possible analytical methodology for quantification of these pesticides, by calculating the rate constant value and its dependence to the pesticide concentration in solution.

In dieser Arbeit wird die Entwicklung eines bifunktionellen Biosensors nach dem Vorbild eines Baukastensystems beschrieben. Das Ziel wird durch die Kombination verschiedenster molekularer Erkennungselemente erreicht. Solche molekularen Erkennungselemente im verwendeten System sind: • Propidium und die periphere anionische Bindungsstelle der Acetylcholinesterase (AChE) • Organophosphate und das aktive Zentrum der AChE • ein an die AChE gekoppeltes Hapten und das Epitop eines Antikörpers • ein an die AChE gekoppeltes Hapten, das als Ligand ein weiteres Enzym bindet Neben dem molekularen Erkennungselement wird ein Biosensor ebenso durch die Art des Transducers charakterisiert. Hier werden Quarzplättchen mit Goldelektroden zur Signalumwandlung eingesetzt. Die Verwendung solcher Sensoren mit einem EQCM-Gerät (electrochemical quartz crystal microbalance) ermöglicht es zwei Messsignale gleichzeitig aufzunehmen: die piezoelektrische Bestimmung einer Massebeladung und die amperometrische Detektion von Enzymaktivität auf der Sensoroberfläche. Für die Analytik stehen somit zwei verschiedene Assay-Varianten zur Verfügung: die Bestimmung der Inhibition der ACHE-Aktivität und ein Bindungstest über das Hapten. Die Basis beider Tests ist die Modifizierung der piezoelektrischen Kristalle mit Propidium – einem reversiblen Inhibitor der Acetylcholinesterase. Dies ermöglicht die Beladung des Sensors mit AChE über die Wechselwirkung mit der peripheren anionischen Bindungsstelle des Enzyms. Die Aktivität der so immobilisierten AChE und die Inhibition durch Organophosphate (Pestizide) werden amperometrisch bestimmt. Durch die chemische Kopplung eines Hapten an die Cholinesterase wird ein weiteres Erkennungselement eingeführt. Das eröffnet die Möglichkeit, an die auf dem Propidium-modifizierten Sensor immobilisierte, haptenisierte Cholinesterase einen Antikörper zu binden. Als Voraussetzung für elektrochemische Bestimmung der AChE-Aktivität wurde zunächst die Optimierung der amperometrischen Messmethode vorgenommen. Die Oxidatationspotentiale für die Detektion von Thiocholin wurden im Bereich von 150 mV bis 300 mV variiert. Dabei wurde für die nachfolgenden Untersuchungen eine Arbeitspotential von 200 mV (vs. Ag/AgCl) festgelegt, da hier das beste Verhältnis von gemessenem Oxidationsstrom und Langzeitstabilität der Propidium-modifizierten Sensoren erzielt wurde. Dieses Potential war deutlich geringer als die bisher publizierten Mediator-freien AChE-Biosensoren. Es wurde ein Vergleich verschiedener Organophosphate über ihre Inhibitionskonstanten durchgeführt, um diejenigen herauszufinden, die möglichst schnell mit dem aktiven Zentrum der Acetylcholinesterase reagieren. Das verwendete Messsystem beruht nicht auf der Vorinkubation der AChE und damit einer Einstellung des Inhibitionsgleichgewichts. Stattdessen wurde die Inhibition der AChE direkt im Fließsystem verfolgt. Daher war eine schnelle Inhibitionskinetik für einen empfindlichen Organophosphat-Nachweis erforderlich. Da einige Inhibitoren nur als Phosphothionat vorlagen, wurde die Überführung dieser Substanzen in die entsprechenden Oxo-Formen mittels N-Bromsuccinimid untersucht. Die NBS-Aktivierung wurde erfolgreich durchgeführt, die erwartete Inhibitionsstärke konnte jedoch aufgrund hydrolytischer Vorgänge nicht erreicht werden. Untersuchungen mit Diisopropylfluorophosphat (DFP) und Chlorpyriphos-oxon (CPO) konnten die Voruntersuchungen über die Inhibitionskinetik in Bezug auf die erreichten Nachweisgrenzen von 2E-06 M für DFP und 5E-08 M für CPO bestätigen. Für die chemische Modifizierung der Acetylcholinesterase wurde zunächst 2,4-Dichlorphenoxyessigsäure (2,4-D) als Hapten ausgewählt. 2,4-D wird als Herbizid eingesetzt und in der EU über die Gewässerschutzrichtlinie reguliert. 2,4-D konnte in unterschiedlichen molaren Verhältnissen von 2,6 : 1 bis 260 : 1 (2,4-D : AChE) nach Aktivierung mit einem Norbornendicarboximido-Derivat an die AChE gekoppelt werden. Dabei konnte die spezifische Aktivität der Acetylcholinesterase erhalten und die Bindung eines anti-2,4-D-Antikörpers ermöglicht werden. Zur Verstärkung des piezolelektrischen Signals der Antikörperbindung wurden die Immunoglobuline zunächst an Goldnanopartikel gekoppelt. Damit konnte eine Verstärkung um den Faktor 10 erreicht werden. Allerdings waren die Antikörper-modifizierten Goldnanopartikel nicht langzeitstabil. Daher wurden auch Silica-Nanopartikel als Matrix für die Antikörperkopplung getestet. Mit diesem System konnte eine Verstärkung um den Faktor von 5 bis 13 je nach Grad der Beladung den Nanopartikel mit Antikörper bestimmt werden. Die hohe unspezifische Bindung der Antikörper-Nanopartikel-Konjugate an den Propidium-modifizierten QCM-Sensor konnte keinen empfindlichen 2,4-D-Nachweis ermöglichen. Als Alternative wurde Kokain (Benzoylecgonin, BZE) als Hapten an die Aceytlcholinesterase gekoppelt. Da Kokain selbst auch als Inhibitor im aktiven Zentrum der AChE binden kann, wurden zwei verschiedene Strategien zur Konjugatsynthese verfolgt. Durch Zugabe von Kokain während der Kopplung sollte die kovalente Fixierung des Kokain-Derivats BZE-DADOO im aktiven Zentrum verhindert werden (Konjugat B). In der Tat konnten mit dieser Synthesestrategie 67% der spezifischen Cholinesterase-Aktivität erhalten werden, während im Kokain-freien Ansatz (Konjugat A) nur 2% der Ausgangsaktivität wiedergefunden wurden. Das BZE-AChE-Konjugat ermöglichte auch die Untersuchung der Bindungskinetik der anti-BZE-Antikörper. Dabei konnte eine Assoziationsgeschwindigkeitskonstante ka von 12911 l/(mol•s) berechnet werden. Dieser Wert ist trotz der vergleichsweise geringen Oberflächenbeladung vergleichbar mit den in der Literatur angegebenen Werten. Die Dissoziationsgeschwindigkeitskonstante ist mit 2,89E−3 1/s um den Faktor 30 höher als der Literaturwert. Diese Abweichung ist auf Unterschiede im Bindungsmodell zurückzuführen. Mit beiden BZE-AChE-Konjugaten konnte ein kompetetiver Immunoassay mit Kokain im Fließsystem durchgeführt werden. Dabei zeigte sich für beide Konjugate ein ähnlicher Testmittelpunkt: IC50 = 4,40E−8 mol/l für Konjugat A bzw. IC50 = 1,77E−8 mol/l für Konjugat B. Diese Werte sind vergleichbar zu bereits publizierten Kokainassays im Fließsystem. Wie vorstehend beschrieben, bindet Kokain als Inhibitor auch im aktiven Zentrum von Cholinesterasen. Diese Eigenschaft wurde genutzt, um ein zweites Enzym – Butyrylcholinesterase (BChE) – an die BZE-AChE zu binden. Die Spezifität dieser Bindung konnte durch die Abwesenheit einer Affinität der BChE zum Propidium und durch die Blockierbarkeit der Bindung von BChE und BZE-AChE durch Kokain nachgewiesen werden. Damit konnte erfolgreich die Kombination mehrere molekularer Erkennungselemente demonstriert werden. Die Propidium-Plattform ermöglicht den Aufbau einer Architektur aus verschiedenen Cholinesterasen, die über unterschiedliche Bindungsstellen wechselwirken. Sowohl freie als auch BZE-modifizierte AChE können über die Affinität zum Propidium auf dem EQCM-Sensor immobilisiert werden. Mit Kokain als Substrat der Butyrylcholinesterase kann Benzoylecgonin nicht nur als Epitop für die Bindung eines Antikörpers, sondern auch als Erkennungselement für die BChE genutzt werden. Auf der anderen Seite erschwert die geringe Affinität der BChE im Gegensatz zum anti-BZE-Antikörper den Einsatz dieses Systems für analytische Zwecke. Durch die Verwendung anderer Ligand-Enzym-Kombinationen läßt sich das in dieser Arbeit vorgestellte Konzept noch weiter ausbauen und ermöglicht damit eine Entwicklung ausgehend von „einfachen“ molekularen Erkennungselementen (MRE) hin zu „multifunktionellen“ Erkennungselementsystemen. In dieser Arbeit konnte demonstriert werden, dass der Aufbau solch komplexe Systeme möglich ist, ohne Abstriche in Bezug auf die Empfindlichkeit der einzelnen Assays hinzunehmen. / This work describes the development of a bifunctional biosensor following a modular assembly approach. This aim is reached through the combination of various molecular recognition elements. The system presented herein uses the following recognition elements: • propidium and the peripheral anionic site of the acetylcholinesterase (AChE) • an organophosphate and the active site of the AChE • a hapten – covalently coupled to the AChE – and the epitope of an antibody • a hapten – covalently coupled to the AChE – binding as a ligand to another enzyme A biosensor is not only characterized by the molecular recognition element, but also by the type of signal transducer. This work is based on an electrochemical quartz crystal microbalance (EQCM) device that uses gold-plated quartz sensors for the signal transduction. This allows monitoring two distinct signals at the same time: the piezoelectric determination of a mass loading and the amperometrical detection of enzymatic activity on the sensor surface. Thus two different assay systems are provided: the determination of the inhibition of the AChE activity and ligand binding assay via the hapten. Both tests are based on the modification of the piezoelectric crystals with propidium – a reversible AChE inhibitor. This allows the deposition of AChE on the sensor surface via the interaction with the enzyme’s peripheral anionic site. The enzymatic activity of the in-situ immobilized AChE and the inhibition by organophosphates (pesticides) are measured amperometrically. Another recognition element is introduced by the chemical coupling of a hapten to the cholinesterase. This provides the opportunity bind an antibody to the haptenized cholinesterase that is immobilized on the propidium-modified sensor. Preliminary experiments were focussed on the improvement of the amperometric determination the AChE activity. The applied potential for the oxidation of thiocholine was changed over a range from 150 to 300 mV. The best results for the measured oxidation current and the long-term stability of the propidium-modified sensors were obtained at 200 mV (vs. Ag/AgCl). This potential was used throughout all subsequent experiments. This potential was also found to be lower as compared to mediator-free AChE-biosensors published hitherto. Different organophosphates were evaluated with regard to their inhibition constants to find those which react with active site of the acetylcholinesterase as fast as possible. The assay format used herein monitors the inhibition of the AChE directly in the flow-system. That is, it is not based preincubation of the enzyme with the inhibitor and therefore no inhibition equilibrium is reached. This approach requires fast inhibition kinetics in order to detect the organophosphates highly sensitively. Some of the inhibitors were only available in the phosphothionate form. Thus was necessary to convert these compounds to their respective oxon-forms by N-bromosuccinimide (NBS). The NBS-activation was performed successfully, though the expected inhibition potential could not be reached due to hydrolytic processes. Experiments with diisopropylfluorophosphate (DFP) und chlorpyriphos-oxon (CPO) could confirm the previous experiments on the inhibtion kinetics. Lower limits of detection of 2E-06 M for DFP and 5E-08 M for CPO could be reached with this approach. Initially 2,4-dichlorphenoxyacetic acid (2,4-D) was chosen as a hapten for the chemical modification of the acetylcholinesterase. The use of 2,4-D as a herbicide is regulated by the water protection directive of the European Union. 2,4-D was coupled to AChE in different molar ratios from 2,6 : 1 to 260 : 1 (2,4-D : AChE) after activation with a norbornendicarboximido derivative. The chosen coupling method allowed to recover the complete specific activity of the acetylcholinesterase and to bind a specific anti-2,4-D-antibody. Furthermore, the coupling of the immunoglobulins to gold nanoparticles was tested to enhance the piezoelectric signal of the antibody binding. An amplification factor of 10 was reached with this system. However the antibody-coated gold nanoparticles show a very poor long-term stability. Therefore also silica nanoparticles were tested as a matrix for the coupling of the antibodies. This approach yielded an amplification factor from 5 to 13 depending amount of antibodies bound to the nanoparticles. Unfortunately the high non-specific binding of the antibody nanoparticle conjugates did not allow a sensitive 2,4-D detection assay. Cocaine (benzoylecgonine, BZE) was coupled as a hapten to Acetylcholinesterase in an alternative approach. Two different strategies for the synthesis of the conjugate were pursued, since cocaine can bind also bind as an inhibitor for the AChE’s active site. The addition of excess cocaine during the coupling reaction should the covalent binding of the cocaine derivative BZE-DADOO at the active site (conjugate B). Indeed over two thirds of the original specific cholinesterase activity could be recovered with this strategy, while the cocaine-free batch (conjugate A) showed only 2% of the original activity. Furthermore the BZE-AChE conjugate allowed the evaluation of the binding kinetics of the anti-BZE-antibody. The association rate constant ka was calculated to 12911 l/(mol•s). Despite the low surface coverage this value is still comparable to other published results. The dissociation rate constant kd of 2,89E−3 1/s is thirty times higher than values found in the literature. This deviation is due to differences in the applied binding model. Both BZE-AChE conjugates could be applied in a competitive immunoassay for cocaine in the flow system. It was shown that for both conjugates a similar half maximal inhibitory concentration was reached: : IC50 = 4,40E−8 mol/l for conjugate A and IC50 = 1,77E−8 mol/l for conjugate B, respectively. These values are comparable to other published assay for cocaine in a flow system. As described earlier, cocaine is also able to bind to the active site of cholinesterases. This feature was used to examine the interaction of a second enzyme – butyrylcholinesterase (BChE) – with the BZE-AChE. Evidence for the specificity of this interaction was provided by two further experiments, i.e. BChE has no affinity towards Propidium and the binding of BChE towards BZE-AChE could be blocked by excess cocaine. Thus the successful integration of recognition elements on the molecular level could be demonstrated. The propidium-modifies sensor allowed the construction of a scaffold of cholinesterases that interact via different recognition sites. Unmodified and BZE-coupled AChE can be immobilized on the EQCM-sensor via the interaction with propidium. With cocaine being a substrate BChE this compound cannot only be used to capture anti-BZE-antibodies, but also as a recognition element for BChE. The affinity of the BChE towards is relatively low as compared to the antibody’s binding strength, thus making it difficult to employ this system for analytical purposes. Still the concept presented herein can be extended by other ligand-enzyme-combinations. On the basis of “simple” molecular recognition elements this enables the development of “multifunctional” recognition element systems. This work could show that the construction of such complex systems is possible without cutting back with regard to the sensitivity of the individual assays.

Nováková D.: Biological activity of secondary plants metabolites I. Alkaloids of Narcissus jonquilla L. Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Department of Pharmaceutical Botany and Ecology, Hradec Králové 2015, pp. 70. The aim of the diploma thesis was a preparation of alkaloid extracts to identification of alkaloid patterns and measure cholinesterase inhibitory activity. This activity is useful for treating Alzheimer's disease. Alkaloid extracts of seven Narcissus jonquilla L. (Amaryllidaceae) varieties (Sundial, Sundisc, Sweetness, Waterperry, Simplex, Twinkling Yellow, Yazz) were studied with respect to their acetylcholinesterase (HuAChE) and butyrylcholinesterase (HuBuChE) inhibitory activity and alkaloid patterns. Twenty-three alkaloids were determined by GC/MS, and ten of them identified from their mass spectra and retention times. All samples exhibited content of galanthamine, most samples contained lycorine and tazettine. Promising HuAChE inhibition activity was demonstrated by Narcissus jonquilla L. cv. Waterperry with IC50 values of 6.53 ± 0.88 μg/mL. The strongest inhibitory activity against HuBuChE was detected in extract from Narcissus jonquilla L. cv. Sundisc with IC50 value of 5.09 ± 0.64 μg/mL. Keywords: Alzheimer's disease, Amaryllidaceae, Narcissus,...

Panchartková, M.: Biological aktivity of secondary plants metabolites III. Alkaloids of Narcissus tazetta L., Diploma thesis, Charles University in Prague, Faculty of Pharmacy in Hradec Králové, Department of Pharmaceutical Botany and Ecology, Hradec Králové, 2015, 67s. Plants from the Amaryllidaceae family contain alkaloids that have multiple biological effects. There is described antiviral, antitumor, antibacterial, antimalarial and anti-fungal effect. Activity against human cholinesterases is important too. The aim of this thesis was to prepare seven alkaloid extracts of individual cultivars of the plants Narcissus and then to realize their GC/MS analysis. Thanks to this analysis, several different structural types of alkaloids from the Amaryllidaceae family were identified. The most frequently identified alkaloids were homolycorine, lycorine, tazettine and galanthamine type. This was followed by the measuring of biological activity against human acetylcholinesterase (HuAChE) and butyrylcholinesterase (HuBuChE). The highest inhibitory activity IC50 identified the alkaloidal extract of the Narcissus jonquilla cv. New baby with the values in relation to HuAChE 13,78 ± 1,48 and in relation to HuBuChE 96,12 ± 9,55. The main reason was probably the highest content of galanthamine of all cultivars,...

A doença de Alzheimer é uma afecção crônica degenerativa que não possui tratamento até o momento. O uso de alimentos funcionais como a romã na prevenção e/ou tratamento de doenças neurodegenerativas têm sido amplamente pesquisados. Diante disto, o presente trabalho teve como objetivo avaliar a quantidade de compostos bioativos (antocianinas, compostos fenólicos e flavonoides), atividade anticolinesterásica e a capacidade antioxidante in vitro e on line dos extratos de polpa e casca de romã e posteriormente estudar o possível efeito neuroprotetor de micropartículas obtidas a partir do extrato da casca de romã em um animal submetido a infusão crônica de peptídeo &beta;-amilóide. O extrato de casca de romã apresentou maior teor de antocianinas, compostos fenólicos, flavonoides e atividade antioxidante in vitro e on line do que o extrato da polpa. Na análise de compostos não voláteis pela técnica de GC-MS foram identificados 38 compostos no extrato da casca e 37 da polpa de romã, sendo o ácido gálico a principal substância detectada. Foram encontrados no total 13 compostos no extrato de casca e 8 no extrato de polpa de romã que apresentaram atividade antioxidante pelo método HPLC-ABTS on line. A punicalagina, epicatequina e ácido gálico foram os compostos determinantes para a atividade antioxidante em ambos os extratos. O extrato da casca de romã apresentou atividade anticolinesterásica superior ao da polpa. Estes resultados, em conjunto, indicaram um possível potencial da casca de romã como um agente neuroprotetor na doença de Alzheimer. Para estudar o possível efeito neuroprotetor do extrato da casca de romã foram utilizados camundongos C57BL/6 cronicamente infundidos com peptídeo &beta;A1-42 e/ou veículo através de mini-bombas osmóticas durante 35 dias e foram avaliados biomarcadores e alterações comportamentais. Micropartículas de extrato de casca de romã, produzidas em spray dryer, foram diluídas em água e administradas na dose de 800 mg de casca de romã/kg de animal/dia. A memória espacial foi avaliada em labirinto de Barnes e uma redução no número de erros para encontrar a caixa de escape foi verificada nos animais tratados com micropartículas de casca de romã e nos animais do grupo controle, mas não nos animais do grupo &beta;A. A atividade da acetilcolinesterase, neurotrofina BDNF, TNF-&alpha; e a enzima SOD foram avaliadas no hipocampo, córtex e soro dos animais. A peroxidação lipídica foi avaliada no fígado dos animais. Como a casca de romã não é comumente consumida foram dosados marcadores de dano isquêmico hepático. O consumo de micropartículas de casca de romã promoveu uma redução do acumulo de placas amiloides, aumento da expressão de neurotrofinas, redução da atividade da enzima acetilcolinesterase, redução da peroxidação lipídica e da citocina pró-inflamatória TNF-&alpha; em animais infundidos com peptídeo &beta;-amilóide. O consumo das microcáspulas de casca de romã não acarretou nenhum tipo de lesão hepática. No geral, verificou-se que os compostos presentes na casca de romã podem apresentar um efeito neuroprotetor em animais submetidos a infusão crônica de peptídeo &beta;-amilóide. / Alzheimer\'s disease is a chronic and degenerative condition that have no treatment until now. The research of functional foods such as pomegranate for the prevention and/or treatment of many conditions, including neurodegenerative diseases, is increasing year after year. The amount of bioactive compounds (anthocyanins, phenolic compounds and flavonoids), acetylcholinesterase activity and antioxidant capacity in vitro and on line of pomegranate peel and pulp extracts were evaluated. Pomegranate peel extract has higher content of anthocyanins, phenolic compounds, flavonoids and antioxidant activity in vitro and on line than pulp. The analyses of the profile of non-volatile compounds identified 38 compounds in the peel and 37 in the pulp. The gallic acid was main compound detected. Pomegranate peel showed 13 compounds with antioxidant activity by the HPLC-ABTS method online and pulp showed eight compounds. Punicalagin, Gallic acid and epicatechin were determinants for the antioxidant capacity of the aqueous-alcoholic extract of pomegranate. Pomegranate peel extract had greater anticholinesterase activity than pulp. These results together indicated a possible potential of pomegranate peel as a neuroprotective agent in Alzheimer\'s disease. This research had as objective to study the possible neuroprotective effect of pomegranate peel on an animal model of the Alzheimer\'s disease. For that purpose, mice model of Alzheimer\'s disease were used and biomarkers and behavioral changes were evaluated. C57BL/6 mice were chronically infused with &beta;A1-42 peptide and/or vehicle by mini - osmotic pumps during 35 days. Microparticles of pomegranate peel extract, produced by spray drying, were diluted in water and administered at a dose of 800 mg of pomegranate peel/ kg animal/day. The spatial memory was evaluated in the Barnes maze and a reduction of the errors to find the scape box was verified in animals treated with the PPE, as observed in the Control group, but not in th A&beta; group. The activity of acetylcholinesterase, neurotrophin BDNF, TNF-&alpha; and SOD were measured in the hippocampus, cortex and serum. Lipid peroxidation was evaluated in the liver. As the pomegranate peel is not commonly consumed, biomarkers of liver ischemic damage were measured. Pomegranate peel consumption promoted a reduction of amyloid plaques, increasing neurotrophin expression, reduction in a AChE activity, reduced lipid peroxidation and reduced TNF-&alpha; in animal models of Alzheimer\'s disease. The consumption of pomegranate peel did not cause liver injury. In general, pomegranate peel showed a neuroprotective effect on animal models of the Alzheimer\'s disease.