Thesis(M.S.)--Auburn University, 2006. / Abstract. Vita. Includes bibliographic references.

Organophosphates (OPs), such as nerve agents and insecticides, potently inhibit acetylcholinesterase (AChE). Oximes, such as the currently FDA approved oxime 2-PAM, remove the OP from the inhibited enzyme. 2-PAM is effective against select OPs and cannot effectively pass the blood-brain barrier to attenuate OP induced CNS damage. Our laboratory has synthesized a series of substituted phenoxyalkyl pyridinium oximes (Patent number: 9,227,937) that have demonstrated increased survival rates compared to 2-PAM. This research investigated 1) in vitro oxime reactivation of rat, human, and guinea pig serum BChE after inhibition by nerve agent and insecticidal OPs; 2) in vitro determination of reactivation kinetic rate constants for OP inhibited human and rat serum BChE and electric eel AChE after inhibition by a sarin surrogate and paraoxon; 3) intranasal delivery of oximes to reactivate brain AChE in vivo after inhibition by a sarin surrogate. Novel oxime 15 demonstrated significant broad spectrum reactivation of OP-inhibited rat serum BChE while novel oxime 20 demonstrated significant broad spectrum reactivation of OP-inhibited human serum BChE. All tested oximes were poor reactivators of OP-inhibited guinea pig serum BChE. Kinetic analysis of reactivation for NIMP and paraoxon human and rat serum BChE and electric eel AChE demonstrated differences in the second order rate constants. Oxime 20 demonstrated reactivation efficiency for both NIMP and paraoxon inhibited rat and human serum BChE and electric eel AChE more effectively than 2-PAM. Intranasal delivery of either oxime 20 or 2-PAM showed attenuation of NIMP-inhibited brain AChE inhibition in select brain regions and select time points. Oxime 20 demonstrated a larger window of effectiveness but neither oxime attenuated brain AChE inhibition in the hindbrain for any time point or for any brain region at the ten minute time point. These data suggest that reactivation of OP-inhibited BChE may be contributing to the observed increases in survival seen with our oximes. Novel oxime 20 demonstrated reactivation efficacy towards both BChE and AChE inhibited enzyme and a rapid entry into the brain after intranasal delivery. Having an oxime that can be effective in a multitude of ways would be of great value to medical and military personnel.

Malaria continues to cause significant mortality in sub-Saharan Africa and elsewhere, and existing vector control measures are being threatened by growing resistance to pyrethroid insecticides.  With the goal of developing new human-safe, resistance-breaking insecticides we have explored several classes of acetylcholinesterase inhibitors.  In vitro assay studies have shown that trifluoromethyl ketones (TFK's) are potent inhibitors of An. gambiae AChE (AgAChE), that inhibit the enzyme by making a covalent adduct with the catalytic serine of the enzyme.  However research in the Carlier group has shown that trifluoromethyl ketones bearing benzene and pyrazole cores have shown very little toxicity to An. gambiae, perhaps due to hydration and rapid clearance. Focus was directed towards synthesis of oximes, oxime ethers, and hydrazones as potential prodrugs to prevent immediate hydration and reach the central nervous system.  The synthesis of various oximes, oxime ethers, and hydrazones has been shown to give cimpounds toxic to Anopheles gambiae within 3- to 4-fold of the toxicity of propoxur. However, thus far we have not been able to link the toxicity of these compounds to a cholinergic mechanism.  Pre-incubation studies suggest that significant hydrolysis of these compounds to TFKs does not occur or 22 h at pH 7.7 or 5.5.   Future work will be directed towards TFKs that have better pharmacokinetic properties.  Work will also be directed at synthesis of oxime and hydrazone TFK isosteres to determine the mechanism of action of these compounds. / Master of Science

Kateřina Janská Evaluation of the kinetics of acetylcholinesterase inhibitors in vitro Diploma thesis Charles University in Prag, Faculty of Pharmacy in Hradec Králové Pharmacy Department of Biological and Medical Sciences Supervisor: Doc. MUDr. Josef Herink, DrSc. Consultant: PharmDr. Vendula Šepsová The aim of the thesis was to determine the type of an inhibition of newly synthesized AChEI and to find out if AChEI structure changes influence the type of an inhibition. Altogether 12 substances (7 tacrine hybrides and 5 7-methoxy- donepezil hybrids) were investigated. The inhibition potential of the tested substances was studied in vitro on the human recombinant AChE. Spectrophotometric Ellman method was utilized as the measurement tool. The noncompetitive type of an inhibition for substances EN 1-5, PC-25 and PC-33, mixed type of an inhibition for substances PC-48 and PC-49, uncompetitive type of an inhibition for substances EN-6, EN-7 and competitive type of an inhibition for the substance PC-37 was determined. The greatest inhibition potential according to Ki values were found for substances EN-7 and PC-37. Substances PC-37 and PC-48 were determined as substances with the biggest affinity to the AChE. The type of an inhibition has been influenced by a substituent position in PC substances and by...

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,...

O Mal de Alzheimer é a causa mais importante de demência em idosos. A progressão dos sintomas da doença está associada com modificações estruturais nas sinapses colinérgicas em determinadas regiões cerebrais e, consequentemente, à diminuição do potencial de neurotransmissão colinérgica. Desta forma, o aumento da capacidade de neurotransmissão colinérgica constitui o mecanismo fundamental dos fármacos utilizados para o tratamento do Mal de Alzheimer. Atualmente, o único tratamento clínico eficaz para o Mal de Alzheimer (MA) é a utilização de inibidores da acetilcolinesterase (AChE). Os anticolinesterásicos são os fármacos mais promissores desenvolvidos até hoje, pois é a única classe terapêutica que mostrou melhora nos sintomas cognitivos do MA. Para esse projeto, foram utilizadas diferentes técnicas de modelagem molecular como estratégia de planejamento racional de fármacos, tendo como base os inibidores de Acetilcolinesterase (AChE) descritos na literatura além dos que possuem estruturas depositadas no PDB, incluindo alguns que já vêm sendo utilizados no tratamento do Mal de Alzheimer. O objetivo foi planejar e testar novos potenciais inibidores desse alvo terapêutico, na tentativa de obter e futuramente otimizar novos protótipos como futuros candidatos a fármacos em Mal de Alzheimer. Os objetivos estendem-se a propostas de novos potenciais protótipos, selecionados de bases de dados de compostos comerciais contendo propriedades de fármacos. Os screenings virtuais foram tendenciados às estruturas dos inibidores já reportados da literatura bem como ao padrão farmacofórico comum a eles, a ser modelado. / Alzheimer\'s disease is the leading cause of dementia in the elderly. The progression of symptoms is associated with structural changes in cholinergic synapses in specific brain regions and consequentely to decrease the potential of cholinergic neurotransmission. Thus, the increased capacity of cholinergic neurotransmission is the fundamental mechanism of the drugs used to treat Alzheimer\'s disease. Currently, the only effective clinical treatment for Alzheimer\'s (MA) is the use of inhibitors of acetylcholinesterase (AChE). Cholinesterase inhibitors are the most promising drugs developed so far, it is the only therapeutic class that showed improvement in cognitive symptoms of MA. For this project, we used different techniques of molecular modeling as a strategy for rational design of drugs based on inhibitors of acetylcholinesterase (AChE) in the literature than those which have structures deposited in the PDB, including some that have already been used in the treatment Alzheimer\'s disease.The objective was to design and test new potential inhibitors of therapeutic target in attempts to obtain and optimize future new prototypes as future drug candidates in Alzheimer\'s disease. The goals extend to proposals from potential new prototypes, selected from databases of commercial compounds containing properties of drugs. The virtual screenings were trends to structures of the inhibitors already reported in the literature as well as the pharmacophoric pattern common to them, to be modeled.

A acetilcolinesterase (AChE) é uma enzima essencial que encerra a transmissão colinérgica através de uma rápida hidrólise do neurotransmissor, acetilcolina (ACh). Uma ampla série de evidências mostraram que os inibidores da AChE podem interferir com a progressão da doença de Alzheimer (DA). O desenvolvimento bem sucedido de compostos inibidores da AChE foi baseado na teoria de que o declínio nas funções cognitivas e mentais associadas a DA está relacionado com a perda da neurotransmissão cortical colinérgica, sendo assim, esses compostos podem ser usados para tratar as deficiências colinérgicas. Uma coleção de moléculas orgânicas foi escaneada para ser avaliada a capacidade dessas moléculas em inibir a atividade enzimática da AChE com o objetivo de se encontrar compostos líderes para posteriores otimizações, conduzindo a fármacos com aumento da eficácia e/ou menores efeitos adversos. As estratégias aplicadas incluem o screening ou triagem virtual baseado na estrutura e também no ligante, modelagem farmacofórica, docking molecular e buscas por similaridade (forma e eletrostática). Os estudos foram também concentrados na descoberta de novas classes de inibidores da AChE, tendo como molécula de referência o fármaco donepezil, o qual inaugurou uma nova classe de inibidores da AChE com a ação mais longa e mais seletiva com efeitos adversos manejáveis. Do total de compostos triados, 50 foram selecionados com adequadas propriedades físico-químicas e ADME/Tox. Em geral, esses compostos possuem substancial interação com o sítio periférico aniônico (PAS) da AChE e a maioria deles faz interações adicionais com o sítio catalítico (CAS) e com outros resíduos de aminoácidos importantes ao longo da enzima. Destes 50 compostos, oito foram comercialmente adquiridos e os ensaios enzimáticos revelaram que estes compostos exibem uma alta afinidade pela AChE. Os resultados apontam, ainda, que o composto entitulado ZINC30019441 exibiu a mais potente atividade inibitória para a AChE, com 1,8 micromolar de concentração, e os demais ficaram ainda situados em baixo micromolar, de 2 a 3 micromolar de concentração. Estes resultados, além das modificações químicas ora propostas in silico para estes inibidores protótipos, apontam para o desenvolvimento de uma nova e promissora série de potentes anticolinesterásicos, contendo propriedades de fármacos, as quais são ainda apropriadas para atuarem no Sistema Nervoso Central e interagirem com o peptídeo beta-amiloide, com vistas ao tratamento quimioterápico da doença de Alzheimer. A perspectiva imediata inclui os ensaios de anti-agregação do peptídeo com os oito inibidores já testados com a Acetilcolinesterase. / Acetylcholinesterase (AChE) is an essential enzyme that terminates cholinergic transmission by rapid hydrolysis of the neurotransmitter acetylcholine (ACh). A wide range of evidence shows that AChE inhibitors may interfere with the progression of Alzheimer\'s disease (AD). The successful development of AChE inhibitor compounds was based on the theory that the decline in cognitive and mental functions associated with AD is related to the loss of cortical cholinergic neurotransmission, thus, these compounds can be used for treating cholinergic deficiencies. A collection of organic molecules has been scanned to evaluate the ability of these molecules to inhibit the enzymatic activity of AChE in order to find lead compounds for further optimization, leading to drugs with increased efficacy and/or fewer adverse effects. The strategies applied include structure-based virtual screening and also in ligand-based virtual screening, pharmacophoric modeling, molecular docking and similarity searches (shape and electrostatic). Studies have also focused on the discovery of new classes of AChE inhibitors, having as a reference molecule the drug donepezil, which has opened a new class of AChE inhibitors with longer and more selective action with manageable side effects. 50 of the compounds screened, were selected with appropriate physical and chemical properties and ADME/Tox. In general, these compounds possess substantial interaction with the peripheral anionic site (PAS) of AChE and most of them make further interact with the catalytic site (CAS) and other key amino acid residues throughout the enzyme. Out of these 50 compounds, eight were commercially purchased and the enzyme assays have shown that these compounds exhibit a high affinity for AChE. The results show also that the compound titled ZINC30019441 exhibited the most potent inhibitory activity for AChE, with 1.8 micromolar concentration, and the rest were still located in low micromolar, 2-3 micromolar concentration. These results as well as chemical modifications herein proposed for these prototypes, indicate the development of a new and promising series of potent anticholinesterase containing drug properties, which are still suitable to act on the central nervous system and interact with the ?-amyloid peptide, for chemotherapy treatment of Alzheimer\'s disease. The immediate prospect includes the peptide anti-aggregation assays with the eight inhibitors already tested against acetylcholinesterase

A acetilcolinesterase (AChE) é uma enzima essencial que encerra a transmissão colinérgica através de uma rápida hidrólise do neurotransmissor, acetilcolina (ACh). Uma ampla série de evidências mostraram que os inibidores da AChE podem interferir com a progressão da doença de Alzheimer (DA). O desenvolvimento bem sucedido de compostos inibidores da AChE foi baseado na teoria de que o declínio nas funções cognitivas e mentais associadas a DA está relacionado com a perda da neurotransmissão cortical colinérgica, sendo assim, esses compostos podem ser usados para tratar as deficiências colinérgicas. Uma coleção de moléculas orgânicas foi escaneada para ser avaliada a capacidade dessas moléculas em inibir a atividade enzimática da AChE com o objetivo de se encontrar compostos líderes para posteriores otimizações, conduzindo a fármacos com aumento da eficácia e/ou menores efeitos adversos. As estratégias aplicadas incluem o screening ou triagem virtual baseado na estrutura e também no ligante, modelagem farmacofórica, docking molecular e buscas por similaridade (forma e eletrostática). Os estudos foram também concentrados na descoberta de novas classes de inibidores da AChE, tendo como molécula de referência o fármaco donepezil, o qual inaugurou uma nova classe de inibidores da AChE com a ação mais longa e mais seletiva com efeitos adversos manejáveis. Do total de compostos triados, 50 foram selecionados com adequadas propriedades físico-químicas e ADME/Tox. Em geral, esses compostos possuem substancial interação com o sítio periférico aniônico (PAS) da AChE e a maioria deles faz interações adicionais com o sítio catalítico (CAS) e com outros resíduos de aminoácidos importantes ao longo da enzima. Destes 50 compostos, oito foram comercialmente adquiridos e os ensaios enzimáticos revelaram que estes compostos exibem uma alta afinidade pela AChE. Os resultados apontam, ainda, que o composto entitulado ZINC30019441 exibiu a mais potente atividade inibitória para a AChE, com 1,8 micromolar de concentração, e os demais ficaram ainda situados em baixo micromolar, de 2 a 3 micromolar de concentração. Estes resultados, além das modificações químicas ora propostas in silico para estes inibidores protótipos, apontam para o desenvolvimento de uma nova e promissora série de potentes anticolinesterásicos, contendo propriedades de fármacos, as quais são ainda apropriadas para atuarem no Sistema Nervoso Central e interagirem com o peptídeo beta-amiloide, com vistas ao tratamento quimioterápico da doença de Alzheimer. A perspectiva imediata inclui os ensaios de anti-agregação do peptídeo com os oito inibidores já testados com a Acetilcolinesterase. / Acetylcholinesterase (AChE) is an essential enzyme that terminates cholinergic transmission by rapid hydrolysis of the neurotransmitter acetylcholine (ACh). A wide range of evidence shows that AChE inhibitors may interfere with the progression of Alzheimer\'s disease (AD). The successful development of AChE inhibitor compounds was based on the theory that the decline in cognitive and mental functions associated with AD is related to the loss of cortical cholinergic neurotransmission, thus, these compounds can be used for treating cholinergic deficiencies. A collection of organic molecules has been scanned to evaluate the ability of these molecules to inhibit the enzymatic activity of AChE in order to find lead compounds for further optimization, leading to drugs with increased efficacy and/or fewer adverse effects. The strategies applied include structure-based virtual screening and also in ligand-based virtual screening, pharmacophoric modeling, molecular docking and similarity searches (shape and electrostatic). Studies have also focused on the discovery of new classes of AChE inhibitors, having as a reference molecule the drug donepezil, which has opened a new class of AChE inhibitors with longer and more selective action with manageable side effects. 50 of the compounds screened, were selected with appropriate physical and chemical properties and ADME/Tox. In general, these compounds possess substantial interaction with the peripheral anionic site (PAS) of AChE and most of them make further interact with the catalytic site (CAS) and other key amino acid residues throughout the enzyme. Out of these 50 compounds, eight were commercially purchased and the enzyme assays have shown that these compounds exhibit a high affinity for AChE. The results show also that the compound titled ZINC30019441 exhibited the most potent inhibitory activity for AChE, with 1.8 micromolar concentration, and the rest were still located in low micromolar, 2-3 micromolar concentration. These results as well as chemical modifications herein proposed for these prototypes, indicate the development of a new and promising series of potent anticholinesterase containing drug properties, which are still suitable to act on the central nervous system and interact with the ?-amyloid peptide, for chemotherapy treatment of Alzheimer\'s disease. The immediate prospect includes the peptide anti-aggregation assays with the eight inhibitors already tested against acetylcholinesterase

O Mal de Alzheimer é a causa mais importante de demência em idosos. A progressão dos sintomas da doença está associada com modificações estruturais nas sinapses colinérgicas em determinadas regiões cerebrais e, consequentemente, à diminuição do potencial de neurotransmissão colinérgica. Desta forma, o aumento da capacidade de neurotransmissão colinérgica constitui o mecanismo fundamental dos fármacos utilizados para o tratamento do Mal de Alzheimer. Atualmente, o único tratamento clínico eficaz para o Mal de Alzheimer (MA) é a utilização de inibidores da acetilcolinesterase (AChE). Os anticolinesterásicos são os fármacos mais promissores desenvolvidos até hoje, pois é a única classe terapêutica que mostrou melhora nos sintomas cognitivos do MA. Para esse projeto, foram utilizadas diferentes técnicas de modelagem molecular como estratégia de planejamento racional de fármacos, tendo como base os inibidores de Acetilcolinesterase (AChE) descritos na literatura além dos que possuem estruturas depositadas no PDB, incluindo alguns que já vêm sendo utilizados no tratamento do Mal de Alzheimer. O objetivo foi planejar e testar novos potenciais inibidores desse alvo terapêutico, na tentativa de obter e futuramente otimizar novos protótipos como futuros candidatos a fármacos em Mal de Alzheimer. Os objetivos estendem-se a propostas de novos potenciais protótipos, selecionados de bases de dados de compostos comerciais contendo propriedades de fármacos. Os screenings virtuais foram tendenciados às estruturas dos inibidores já reportados da literatura bem como ao padrão farmacofórico comum a eles, a ser modelado. / Alzheimer\'s disease is the leading cause of dementia in the elderly. The progression of symptoms is associated with structural changes in cholinergic synapses in specific brain regions and consequentely to decrease the potential of cholinergic neurotransmission. Thus, the increased capacity of cholinergic neurotransmission is the fundamental mechanism of the drugs used to treat Alzheimer\'s disease. Currently, the only effective clinical treatment for Alzheimer\'s (MA) is the use of inhibitors of acetylcholinesterase (AChE). Cholinesterase inhibitors are the most promising drugs developed so far, it is the only therapeutic class that showed improvement in cognitive symptoms of MA. For this project, we used different techniques of molecular modeling as a strategy for rational design of drugs based on inhibitors of acetylcholinesterase (AChE) in the literature than those which have structures deposited in the PDB, including some that have already been used in the treatment Alzheimer\'s disease.The objective was to design and test new potential inhibitors of therapeutic target in attempts to obtain and optimize future new prototypes as future drug candidates in Alzheimer\'s disease. The goals extend to proposals from potential new prototypes, selected from databases of commercial compounds containing properties of drugs. The virtual screenings were trends to structures of the inhibitors already reported in the literature as well as the pharmacophoric pattern common to them, to be modeled.

Nicotinic acetylcholine receptors are ligand-gated ion channels which are located on neuromuscular junction and in central and perifric nervous system. Activity of nicotinic receptor might be modulated by variety of pharmacological agents. In this work, we have focused on the study of the inhibition effect of tacrine and its derivatives on the nicotinic acetycholine receptors of muscle and neuronal type. These derivatives function as acetylcholinesterase inhibitors and also interact with nicotinic acetylcholine receptors. The majority of current forms of treatment of Alzheimer's disease is based on cholinesterase inhibitors. We have studied the mechanism of tacrine and its derivatives by using patch clamp method in the configuration of whole-cell recording. Powered by TCPDF (www.tcpdf.org)