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Wasserstoffatomdynamik in Radikalen, Clustern und BiomolekülenZierhut, Matthias. January 1900 (has links) (PDF)
Würzburg, Universiẗat, Diss., 2005. / Erscheinungsjahr an der Haupttitelstelle: 2004.
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Simulation of nonadiabatic dynamics and time-resolved photoelectron spectra in the frame of time-tependent density functional theoryWerner, Ute 25 July 2011 (has links)
Ziel dieser Arbeit war die Entwicklung einer allgemein anwendbaren Methode für die Simulation von ultraschnellen Prozessen und experimentellen Observablen. Hierfür wurden die Berechnung der elektronischen Struktur mit der zeitabhängigen Dichtefunktionaltheorie (TDDFT) und das Tully-Surface-Hopping-Verfahren für die nichtadiabatische Kerndynamik auf der Basis klassischer Trajektorien miteinander kombiniert. Insbesondere wurde eine Beschreibung der nichtadiabatischen Kopplungen für TDDFT entwickelt. Diese Methode wurde für die Simulation noch komplexerer Systeme durch die Tight-Binding-Näherung für TDDFT erweitert. Da die zeitaufgelöste Photoelektronenspektroskopie (TRPES) ein exzellentes experimentelles Verfahren für die Echtzeitbeobachtung von ultraschnellen Prozessen darstellt, wurde eine TDDFT-basierte Methode für die Simulation von TRPES entwickelt. Der Methode liegt die Idee zu Grunde, das System aus Kation und Photoelektron näherungsweise durch angeregte Zustände des neutralen Moleküls oberhalb der Ionisierungsgrenze zu beschreiben. Um diese Zustände mit TDDFT berechnen zu können wurde eine Beschreibung der Übergangsdipolmomente zwischen angeregten TDDFT-Zuständen entwickelt. Des Weiteren wurden Simulationen im Rahmen des Stieltjes-Imaging-Verfahrens, das eine Möglichkeit der Rekonstruktion des Photoelektronenspektrums aus den spektralen Momenten bietet, durchgeführt. Diese spektralen Momente wurden aus den diskreten TDDFT-Zuständen berechnet. Die breite Anwendbarkeit der entwickelten theoretischen Methoden für die Simulation von komplexen Systemen wurde an der Photoisomerisierung in Benzylidenanilin sowie der ultraschnellen Photodynamik in Furan, Pyrazin und mikrosolvatisiertem Adenin illustriert. Die dargestellten Beispiele demonstrieren, dass die nichtadiabatische Dynamik im Rahmen von TDDFT bzw. TDDFTB sehr gut für die Untersuchung und Interpretation der ultraschnellen photoinduzierten Prozesse in komplexen Molekülen geeignet ist. / The goal of this thesis was the development of a generally applicable theoretical framework for the simulation of ultrafast processes and experimental observables in complex molecular systems. For this purpose, a combination of the time-dependent density functional theory (TDDFT) for the description of the electronic structure with the Tully''s surface hopping procedure for the treatment of nonadiabatic nuclear dynamics based on classical trajectories was employed. In particular, a new approach for the calculation of nonadiabatic couplings within TDDFT was devised. The method was advanced for the description of more complex systems such as chromophores in a solvation shell by employing the tight binding approximation to TDDFT. Since the time-resolved photoelectron spectroscopy (TRPES) represents a powerful experimental technique for real-time observation of ultrafast processes, a TDDFT based approach for the simulation of TRPES was developed. The basic idea is the approximate representation of the combined system of cation and photoelectron by excited states of the neutral species above the ionization threshold. In order to calculate these states with TDDFT, a formulation of the transition dipole moments between excited states within TDDFT was devised. Moreover, simulations employing the Stieltjes imaging (SI) procedure were carried out providing the possibility to reconstruct photoelectron spectra from spectral moments. In this work, the spectral moments were calculated from discrete TDDFT states. The scope of the developed theoretical methods was illustrated on the photoisomerization in benzylideneaniline as well as on the ultrafast photodynamics in furan, pyrazine, and microsolvated adenine. The examples demonstrate that the nonadiabatic dynamics simulations based on TDDFT and TDDFTB are particularly suitable for the investigation and interpretation of ultrafast photoinduced processes in complex molecules.
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Os efeitos do ácido cafeico e do éster fenetil do ácido cafeico sobre as atividades da acetilcolinesterase e das ecto-nucleotidases em ratos / THE EFFECTS OF CAFFEIC ACID AND CAFFEIC ACID PHENETHYL ESTER ON THE ACTIVITIES OF ACETYLCHOLINESTERASE AND ECTO-NUCLEOTIDASES IN RATSAnwar, Javed 21 January 2013 (has links)
Conselho Nacional de Desenvolvimento Científico e Tecnológico / Phenolic compouds and their derivatives constitute a leading family of natural compounds. Caffeic acid (CA) and
caffeic acid phenethyl ester (CAPE) are the important members of phenolic compound, sharing several biological
applications; antioxidant, neuroprotective, anti-inflammatory, antiproliferative, antibacterial, antiviral, antiatherosclerotic and
anticancer properties. In spite of these, literature reportes some of its pro-oxidants activity depending on cellular
environment. These pathophysiolocal properties increased the interest to evaluate the effect of CA and CAPE on the enzyme
evolved in the purines salvage and the acetylcholine hydrolyzing enzyme the acetylcholineterase (AChE); in both PNS and
CNS, since the essential constituent of our dietary items. Previously, our research group has reported that phenolic compound
altered the activities of these enzymes. The AChE rapidly hydrolyzes the acetylcholine in neuronal and non neuronal tissues,
mediating several neurodegenerative diseases. Beside the ACh, ATP (as co-neurotramittors) and adenosine are important
signaling molecules, communicating cells in both PNS and CNS. In the extracellular signalling pathways; the adenine
nucleotides, their derivative and the coupling of these molecules with specific receptor have a crucial role in nervous,
vascular and immune systems. Once released, these molecules are hydrolyzed by a cascade of enzymes including
ectonucleoside triphosphate diphosphohydrolase (NTPDase; E.C. 3.6.1.5, CD39), 5 -nucleotidase (E.C 3.1.3.5, CD73),
ectonucleotide pyrophosphatase/phosphodiesterase (E-NPP), modulating crucially the signaling pathways in the normal
functioning of nervous, vascular and immune systems. Next, adenosine deaminase (ADA) and xanthin oxidase (XO) degrade
the adenosine and xanthine respectively which further control the functioning mechanisms in cellular events. Found in the
neuronal and non neuronal (in both PNS and CNS) the AChE, NTPDase, 5'-nucleotidase, E-NPP, and ADA regulate several
events including neurotransmission, inflammation, and thrombogenic process. We hypothesized to evaluate first the in vitro
effects of CA on AChE activity in peripheral and central cholinergic system of rats. The results showed that CA significantly
modulated the cholinergic system in vitro. By modulating the cholinergic system in vitro, apparently CA (e.g. phenolic
structure) has proper role in neurotransmission. Therefore we hypothesizes to evaluate the in vivo effects of CA on AChE,
NTPDase, E-NPP, 5'-nucleotidase, platelets aggregation and (ADA) in different tissues/cell from rats. The animals were
treated during 30 days and killed after behavioral test. The results showed that caffeic acid increased significantly the AChE
activity in hippocampus, hyphothalmus, pon and lymphocytes while that in cortex, cerebellum and striatum the AChE was
inhibited. CA improves step-down latencies in the inhibitory avoidance. Investigating the in vivo effects of CA in purinergic
system, caffecid acid increased the ATP and AMP hydrolysis in synaptosomes. However, in the synaptosomes no alterations
were observed in the ADA activity in the groups evaluated in this study. CA increased the ATP and AMP hydrolysis, while
the ADP hydrolysis was decreased in platelets. In the present findings caffeic acid decreased the platelets aggregation
induced by ADP agonist. Treatment with CA also increased the NTPDase and ADA activities in lymphocytes of rats.
Considering the dual function of caffeic acid in vitro and in vivo, the present study was extended to CAPE followed by acute
treatment model (ip) in order to elucidate the effect of another phenolic structure on the same parameters. In this line the
animals were treated (ip) with CAPE and killed after 40 minutes. In platelets, the results showed that the effect of CAPE
increased the NTPDase, E-NPP, 5 -nucleotidase activities, while ADA activities did not change significantly. In
synaptosomes CAPE significantly inhibited the NTPDase, and 5 -nucleotidase activity. CAPE induced no significant changes
in ADA in synaptosomes but reduced XO in whole brain. Finaly we investigated the activity of AChE in cortex, cerebellum,
striatum, hippocampus, hyphotalamus, pon, lymphocytes and muscules of rats treated with CAPE. The results showed that
CAPE significantly decreased the AChE activity in cortex cerebellum and striatum. CAPE significantly increased the AChE
activity in hippocampus hypothalamus, pons, muscle and lymphocytes. In cholinergic system our results clearly
demonstrating that both compound with dual functions.These findings demonstrated that the AChE activities and the cascade
of ecto-enzymes was alter in different tissues after treatment with CA and CAPE in rats, suggesting that these compound
should be considered a potentially therapeutic agent in immune, vascular and neurological disorders related with the
cholinergic purinergic system. / Os compostos fenólicos e seus derivados constituem uma importante família de
compostos naturais. O ácido cafeico (AC) e o éster fenetil do ácido cafeico
(CAPE) são membros importantes dessa família e compartilham algumas
aplicações biológicas, tais como: antioxidante, neuroprotetor, antiinflamatório,
antiproliferativo, antibacteriano, antiviral, antiaterosclerótico e anticancerígeno.
Entretanto, a literatura relata algumas atividades pró-oxidantes, dependendo do
ambiente celular. Devido a estas propriedades patofisiológicas, aumentou o
interesse com o objetivo de avaliar o efeito de CA e CAPE sob as atividades
das enzimas purinérgicas e da acetilcolinesterase (AChE), tanto no Sistema
Nervoso Periférico (SNP) como no Sistema Nervoso Central (SNC).
Previamente, nosso grupo de pesquisa relatou que o composto fenólico tem a
capacidade de alterar as atividades dessas enzimas. A AChE rapidamente
hidrolisa a acetilcolina (ACh) em tecidos neuronais e não neuronais, mediando
algumas doenças neurodegenerativas. Ao lado da ACh, o ATP (como coneurotransmissor)
e adenosina são importantes moléculas sinalizadoras,
comunicando as células em ambos os SNP e do SNC. Nas vias de sinalização
extracelulares, os nucleotídeos de adenina e seus derivados podem ser
acoplados a receptores específicos e desse modo ter um papel crucial no
sistema nervoso, sistema vascular e imune. Uma vez liberadas, estas
moléculas são hidrolisadas por uma cascata de enzimas incluindo a
ectonucleosídeo trifosfato difosfoidrolase (NTPDase; EC 3.6.1.5, CD39), 5'-
nucleotidase (EC 3.1.3.5, CD73), ectonucleotideo pirofosfatase/fosfodiesterase
(E-NPP), modulando definitivamente as vias de sinalização do funcionamento
normal do sistema nervoso, sistema vascular e imune. Além disso, a adenosina
deaminase (ADA) e a xantina oxidase (XO) degradam a adenosina e a xantina,
respectivamente, as quais controlam o funcionamento de mecanismos em
eventos celulares. As enzimas encontradas em tecidos neuronais e não
neuronais como a AChE, a NTPDase, a 5'-nucleotidase, a E-NPP e a ADA
regulam eventos celulares incluindo a neurotransmissão, inflamação e
processos trombogênicos. Com essas informações, nós introduzimos a
hipótese de avaliar primeiramente os efeitos in vitro de CA na atividade da
AChE periférica e no sistema central colinérgico de ratos. Os resultados
demonstraram que o CA modula significativamente o sistema colinérgico no
estudo in vitro. Essa modulação demonstra aparentemente que o CA (estrutura
fenólica) possui propriedades de ação que altera a neurotransmissão. Portanto,
a hipótese de se avaliar os efeitos in vivo de CA na atividade da AChE,
NTPDase, E-NPP, 5'-nucleotidase, ADA e da agregação de plaquetas em
diferentes tecidos de ratos tornou-se evidente. Para esse estudo, os animais
foram tratados durante 30 dias e sacrificados após o teste comportamental. Os
resultados do experimento demonstraram que o CA aumentou
significativamente a atividade da AChE em hipocampo, hipotálamo, ponte e nos
linfócitos, enquanto que no córtex cerebral, cerebelo e estriado a AChE foi
inibida. No teste comportamental o CA teve evolução de melhora na latência de
passos da esquiva inibitória. A investigação dos efeitos in vivo do CA no
sistema purinérgico demonstrou aumento na hidrólise de ATP e AMP em
sinaptossomas. Entretanto, não foram observadas alterações significativas na
atividade da ADA em sinaptossomas dos grupos avaliados neste estudo. Em
plaquetas, o CA aumentou significativamente a hidrólise de ATP e AMP,
enquanto que a hidrólise de ADP foi diminuída nesse tecido. No presente
estudo o CA reduziu significativamente a agregação de plaquetas induzida pelo
agonista ADP. Além disso, o tratamento com CA aumentou significativamente
as atividades da NTPDase e da ADA em linfócitos de ratos. Considerando a
dupla função de CA, in vitro e in vivo, o presente estudo foi estendido para
CAPE seguindo o modelo de tratamento agudo pela via intraperitoneal (ip) com
o objetivo de elucidar o efeito de uma segunda estrutura fenólica sobre os
mesmos parâmetros. Nesta linha de pesquisa, os animais foram tratados ip
com CAPE e eutanasiados após 40 minutos. Em plaquetas, os resultados
demonstraram que o CAPE aumentou significativamente a atividade da
NTPDase, E-NPP e 5'-nucleotidase, enquanto que a atividade da ADA não foi
alterada significativamente. Em sinaptossomas, o CAPE inibiu
significativamente a atividade da NTPDase e da 5'-nucleotidase. O CAPE não
induziu alterações significativas na atividade da ADA em sinaptossomas, mas
reduziu significativamente a atividade da XO em todo o cérebro. Finalmente,
nós investigamos a atividade da AChE no córtex cerebral, cerebelo, estriado,
hipocampo, hipotálamo, ponte, linfócitos e músculos de ratos tratados com
CAPE. Os resultados demonstraram que CAPE diminuiu significativamente a
atividade da AChE em córtex cerebral, cerebelo e estriado. O CAPE aumentou
significativamente a atividade da AChE em hipotálamo, hipocampo, ponte,
músculo e linfócitos. No sistema colinérgico, nossos resultados demonstram
claramente que ambos os compostos possuem dupla função. Estes resultados
demonstram que as atividades da AChE e da cascata das ecto-enzimas foram
alteradas em diferentes tecidos após o tratamento com CA ou CAPE em ratos,
sugerindo que estes compostos devem ser considerados agentes com
potencial terapêutico em doenças imunes, vasculares e neurológicas
relacionadas com o sistema colinérgico e purinérgico.
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