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  • About
  • The Global ETD Search service is a free service for researchers to find electronic theses and dissertations. This service is provided by the Networked Digital Library of Theses and Dissertations.
    Our metadata is collected from universities around the world. If you manage a university/consortium/country archive and want to be added, details can be found on the NDLTD website.
151

Vliv kofeinu na změnu reakční doby / The influence of caffeine on the change of reaction time.

BAUEROVÁ, Miroslava January 2014 (has links)
Thesis is focusing on influence of caffeine on the change of reaction time of individual. The theoretical part consists of the introduction of the specific subject and is following by information about positive and negative caffeine effect on the human body. Certain part of dissertation presents some liquid food products, where caffeine is included. The description of the reaction time of the individual before and after consumption is mentioned as well. The practical part of thesis pays attention to the experimentation with the pre-selected sample of person. The test itself was based upon usage of the reaction measurement tool with the optical stimulus for inputs. The objective of the practical part was to compare the influence of caffeine, and its specific amount, on the reaction abilities of selected individuals. Recorded data have been than statically evaluated, and prepared to final comparison. Based on receiving information the unequivocal deduction was determined.
152

Caffeine : evidence-based guidance for use during upper-body exercise and for individuals with a spinal cord injury

Graham-Paulson, Terri S. January 2016 (has links)
The use of nutritional supplements (NS) is common in able-bodied (AB) athletic populations and good evidence exists for a number of NS such as sports drinks, protein powder, creatine, caffeine and buffering agents. However, little evidence is available regarding the popularity and efficacy of NS in a population of athletes with physical impairments.
153

Efeito do ultrassom de alta intensidade na extração e difusão da cafeína nos grãos de café (Coffea arabica)

Huamaní Meléndez, Víctor Justiniano [UNESP] 21 September 2012 (has links) (PDF)
Made available in DSpace on 2014-06-11T19:24:46Z (GMT). No. of bitstreams: 0 Previous issue date: 2012-09-21Bitstream added on 2014-06-13T20:32:11Z : No. of bitstreams: 1 huamanimelendez_vj_me_sjrp_parcial.pdf: 569064 bytes, checksum: a421744f281164e37617b166ac6f3843 (MD5) Bitstreams deleted on 2014-10-03T16:24:34Z: huamanimelendez_vj_me_sjrp_parcial.pdf,Bitstream added on 2014-10-03T16:27:33Z : No. of bitstreams: 2 huamanimelendez_vj_me_sjrp_parcial.pdf.txt: 53713 bytes, checksum: 111b3a17f7877d22607c79773592bd40 (MD5) 000698203.pdf: 2310634 bytes, checksum: 632d409df815fe5814967be2a2659bf4 (MD5) Bitstreams deleted on 2014-10-03T16:33:11Z: 000698203.pdf,Bitstream added on 2014-10-03T16:43:25Z : No. of bitstreams: 2 huamanimelendez_vj_me_sjrp_parcial.pdf.txt: 53713 bytes, checksum: 111b3a17f7877d22607c79773592bd40 (MD5) 000698203.pdf: 2310634 bytes, checksum: 632d409df815fe5814967be2a2659bf4 (MD5) Bitstreams deleted on 2014-10-03T16:48:51Z: 000698203.pdf,Bitstream added on 2014-10-03T16:49:44Z : No. of bitstreams: 1 000698203.pdf: 2310634 bytes, checksum: 632d409df815fe5814967be2a2659bf4 (MD5) Bitstreams deleted on 2014-10-27T11:47:01Z: 000698203.pdf,Bitstream added on 2014-10-27T11:48:02Z : No. of bitstreams: 1 000698203.pdf: 2310634 bytes, checksum: 632d409df815fe5814967be2a2659bf4 (MD5) / Oea / A presente pesquisa propõe como alternativa melhorar o processo de extração da cafeína dos grãos de café de variedade arábica utilizando água como solvente com auxílio de ultrassom de alta intensidade. Na primeira etapa da pesquisa foram avaliadas propriedades físicas do grão no processo de hidratação e a proposição da solução analítica para a semiesfera da equação de Fick. Na segunda etapa foi avaliado o coeficiente de difusão da cafeína no processo de extração com água em diferentes temperaturas (30, 40, 50 e 60 °C). Na terceira etapa foi empregado um delineamento composto central rotacional para avaliar a porcentagem de recuperação e o coeficiente de difusão de cafeína nos grãos de café, para os tempos de 15, 30 e 60 minutos sob a influência do ultrassom de alta intensidade (30, 45, 65, 85 e 100% da amplitude da potência) em diferentes ciclos de aplicação (30, 45, 65, 85 e 100%) e em função da temperatura de extração (30, 36, 45, 53 e 60 °C). O modelo matemático para geometria semiesférica apresentou melhor ajuste aos dados experimentais, tanto para a difusão de água nos grãos de café no processo de hidratação, como para o processo de extração de cafeína em meio aquoso. O coeficiente de difusão de água no grão de café no processo de hidratação variou de 6,901 .10-11 m2 s-1 a 30 °C até 3,119 .10-10 m2 s-1 a 60 °C, com energia de ativação de 41,243 kJ mol-1. Para a difusão da cafeína, o modelo matemático para semiesfera também resultou ser ligeiramente superior na maioria dos casos, onde o coeficiente de difusão variou de 1,026 .10-11 m2 s-1 a 30 °C até 9,004 .10-11 m2 s-1 a 60 °C com uma energia de ativação de 59,933 kJ mol-1. Na aplicação de ultrassom de alta intensidade, os fatores de potência de ultrassom e a temperatura... / This research proposes as an alternative to improve the process of extracting caffeine from coffee beans, arabica variety, using water as solvent, assisted by high-intensity ultrasound. In the first stage of the research, physical properties of the grain were evaluated in the hydration process and the proposition of an analytical solution for the semi-sphere of the Fick equation. In the second stage, it was determined the diffusion coefficient of caffeine in the extraction process with water at different temperatures (30, 40, 50 and 60 °C). In the third stage, a central composite rotational design was used to assess the percentage of recovery and the diffusion coefficient of caffeine in coffee beans, for caffeine extraction upon different treatment times (15, 30 and 60 minutes) under the influence of high-intensity ultrasound (30, 45, 65, 85 and 100% of the power amplitude), different application cycles (30, 45, 65, 85 and 100%), as a function of the temperature (30, 36, 45, 53 and 60 °C). The mathematical model presented by the semispherical geometry showed the best fit to the experimental data, in comparison to Fick's sphere geometry approach, both for the diffusion of water in the coffee beans in the hydration process, and for the extraction process of caffeine in aqueous media. The diffusion coefficient of water in the coffee bean in the hydration process ranged from 6.901 ×10-11 m2 s-1 at 30°C to 3.119 ×10-10 m2 s-1 at 60°C, with and activation energy of 41.243 kJ mol-1. For the diffusion of caffeine in the grain, the semi-sphere mathematical model also resulted slightly better fitting in most cases, with a diffusion coefficient ranged from 1.026 ×10-11 m2 s-1 at 30°C to 9.004 10-11 m2 s-1 at 60°C, and an activation energy of 59.933 kJ mol-1. In the high-intensity ultrasound assisted extraction process, the ultrasound... (Complete abstract click electronic access below)
154

Consumo materno de cafeína durante a gestação em diferentes ambientes intrauterinos e sua relação com medidas antropométricas de crianças nos primeiros meses de vida

Medeiros, Thamíris Santos de January 2016 (has links)
Objetivo: Investigar a associação entre ingestão materna de cafeína durante o período gestacional e as medidas antropométricas de crianças aos três e seis meses de vida. Métodos: Estudo observacional longitudinal, utilizando uma amostra de conveniência de duplas mãe-filho divididos em cinco grupos: gestantes diabéticas (DM), hipertensas (HAS), tabagistas (TAB), que tiveram filhos pequenos para idade gestacional (PIG) e um grupo controle (CTL). A amostra foi selecionada em três hospitais de Porto Alegre, capital do Rio Grande do Sul, no período de 2011 a 2015. Avaliou-se a ingestão materna de cafeína na gestação por Questionário de Frequência Alimentar (QFA) realizado no sétimo dia pós-parto. Os recém-nascidos foram avaliados ao nascimento, aos três e seis meses. As medidas antropométricas utilizadas foram peso, comprimento e dobras cutâneas (DC). As análises foram realizadas por regressão linear. Resultados: A amostra foi composta por 272 duplas mãe-filho: 41 DM, 26 HAS, 68 TAB, 25 PIG e 112 CTL. Não houve diferença em peso e comprimento dos filhos de consumidoras e não consumidoras de cafeína (p>0,05). As crianças do grupo DM tiveram a maior média ajustada para DC aos três meses de idade. Houve interação entre o consumo de cafeína na gestação e a soma das DC das crianças aos três meses de idade para os grupos DM e CTL (p<0,05). A diferença da média ajustada das DC e a interação delas com o consumo de cafeína não foram observadas aos seis meses. Conclusões: O consumo materno de cafeína influenciou nos valores de DC aos três meses de idade, diminuindo-as para as crianças do grupo DM e aumentando-as no grupo CTL. / Objective: To investigate the association between maternal caffeine intake during pregnancy and anthropometric measures of infant at three and six months. Methods: A longitudinal observational study using the mother-child pairs in convenience sample divided into five groups of pregnant women: diabetic (DM), hypertensive (HYP), smokers (SMO), who had small children for gestational age (SGA) and a control group (CTL). Researchers selected the sample in three public hospitals in Porto Alegre, South of Brazil, in the period from 2011 to 2015. Food Frequency Questionnaire (FFQ) evaluated the maternal caffeine intake during pregnancy on the seventh day postpartum. Anthropometric measures used were weight, length, and skinfold thickness (SK). They assessed at birth, at three and six months of child. Linear regression was used to analyze the interaction between caffeine intake and SK. Results: We investigated 272 mother-child pairs: 41 DM, 26 HYP, 68 SMO 25 SGA and 112 CTL. There were no differences in children’s anthropometric measures of mothers consuming and not consuming caffeine (P >0.05). Children of DM group had the highest adjusted average for skinfolds at 3 months. There was interaction between caffeine consumption during pregnancy and the sum of SK of children at 3 months for DM and CTL groups (P <0.05). The difference between adjusted means for SKs infant and caffeine consumption by pregnant women were not observed at six months. Conclusions: Maternal caffeine intake influenced values of SKs at 3 months of age, reducing to the children of the DM group and increasing in the CTL group.
155

Teores de metilxantinas e metabolismo de cafeína em frutos de guaraná (Paullinia cupanavar. sorbilisKunth.) / Methylxanthine content and caffeine metabolism in guarana fruits (Paullinia cupanavar. sorbilisKunth.)

Schimpl, Flávia Camila, 1987- 23 August 2018 (has links)
Orientador: Paulo Mazzafera / Dissertação (mestrado) - Universidade Estadual de Campinas, Instituto de Biologia / Made available in DSpace on 2018-08-23T20:50:20Z (GMT). No. of bitstreams: 1 Schimpl_FlaviaCamila_M.pdf: 3074978 bytes, checksum: 589ce5b09a9c5f294c4bd4eaaff896b1 (MD5) Previous issue date: 2013 / Resumo: Alguns grupos de plantas caracterizam-se por acumularem cafeína. Chá, café e guaraná, que acumulam cafeína, são algumas dessas plantas. As sementes de guaraná possuem o maior teor de cafeína já descrito em plantas, entre 2,5 e 6%. A popularização dos produtos a base de guaraná e a alta demanda por cafeína natural (obtida por descafeinação de plantas) destacam o interesse comercial pela espécie. A biossíntese de cafeína em plantas foi extensivamente estudada em café e chá e ambas espécies têm as mesmas vias chave da biossíntese da cafeína. O terceiro passo da via ocorre na presença de teobromina sintase (TS), enzima com atividade específica na conversão de 7-metilxantina em teobromina, e/ou dependendo da espécie, na presença de cafeína sintase (CS), uma enzima bifuncional que atua nos dois últimos passo da síntese de cafeína, na conversão da 7-metilxantina para teobromina e posteriormente desta para cafeína. O objetivo desta tese foi caracterizar os níveis de metilxantinas, atividade e expressão de CS em frutos de guaraná, sendo que para isto foram realizadas análises bioquímicas e moleculares nos tecidos de cinco cultivares (BRS-Amazonas, BRS-CG372, BRS-CG611, BRS-Maués, BRS-Luzéia). Teobromina acumulou preferencialmente em folhas (estádios jovem, intermediária e madura), caule (porção apical e basal), inflorescência, pericarpo de frutos nos estádio verde, intermediário e maduro. Nas sementes, a cafeína foi o alcaloide que acumulou em maior quantidade e atingiu níveis entre 3,3 e 5,8%. Nos tecidos analisados, seja teobromina ou cafeína, a maior concentração do alcaloide foi em tecidos novos, reduzindo com o desenvolvimento. Enquanto que teofilina foi encontrada em quantidades baixas em todos os materiais. A maior concentração de cafeína em frutos imaturos foi confirmada pela maior atividade de CS e maior expressão de PcCS. A busca do gene da CS de guaraná no banco de sequências EST Realgene gerou uma sequencia de nucleotídeos (PcCS) com 1080 pb, que apresenta semelhança filogenética com proteínas de CS de cacau (BCS1) e chá (TCS1 e TCS2). A produção da proteína recombinante permitiu a caracterização funcional de PcCS como uma CS bifuncional, capaz de catalisar os dois últimos passos de metilação da biossíntese de cafeína. PcCS mostrou afinidade para 7-metilxantina e teobromina (maior afinidade), diferindo das CS descritas para outras espécies acumuladoras de cafeína, que possuem maior afinidade por paraxantina. Provavelmente isto se deve aos resíduos de aminoácidos presentes no sítio ativo da proteína predita, quando comparada com a de café / Abstract: Some plants are characterized by presenting high contents of caffeine. Tea, coffee and guarana, which accumulate the alkaloid caffeine, are some of these plants. Guarana seeds have the highest caffeine content (2.5 and 6%) among plants accumulating methylxanthine alkaloids. The increase in popularity of products made from guarana and the high demand for natural caffeine (obtained by decaffeination plant) justify the commercial interest for this species. The biosynthesis of caffeine in plants has been extensively studied in coffee and tea and both species present high similarity regarding the caffeine biosynthesis pathway. The third step of the pathway occurs in the presence of the enzyme theobromine synthase (TS), which converts 7-methylxanthine to theobromine but depending on the species, this step is also mediated by caffeine synthase (CS), an bifunctional enzyme that in addition to convert 7-methylxanthine to theobromine, also convert the later to caffeine. The aim of this study was to characterize the levels of methylxanthine alkaloids, activity and expression of caffeine synthase in the guarana fruit, and for this biochemical and molecular analyses were carried out in tissues of five cultivars of guarana (BRS-Amazonas, BRS-CG372, CG611-BRS, Maués-BRS, BRS-Luzéia). Theobromine was preferentially accumulated in the leaves (young, intermediate and mature stages), stems (apical and basal sections), inflorescence, and pericarp of fruits (green, intermediate and mature stages). However caffeine accumulated in the seeds as the main alkaloid and reached levels between 3.3 and 5.8%. In all tissues analyzed, whether theobromine or caffeine, the alkaloid concentration was higher in new tissues, reducing with the development/maturation. While theophylline was found in low amounts in all materials. The highest concentration of caffeine in immature fruits was confirmed by the highest activity of CS and highest expression of PcCS. The search for the CS gene of guarana in the EST guarana database Realgene generated a sequence of nucleotides (PcCS) with 1080 bp, which presented phylogenetic similarity with proteins of caffeine synthase from cocoa (BCS1) and tea (TCS1 and TCS2). The production of the PcCS recombinant protein allowed the functional characterization of the enzyme as a bifunctional CS, able to catalyze the two last methylation steps in the biosynthesis of caffeine. PcCS showed affinity for 7-methylxanthine and theobromine (highest), differing from the CS described for other species accumulating caffeine, which have highest affinity paraxanthine. This is probably due to the amino acid residues present in the active site of the predicted protein when compared to coffee / Mestrado / Biologia Vegetal / Mestra em Biologia Vegetal
156

Desenvolvimento de bioprocesso para produção de cafeina e teofilina dementilases por Rhizopus delemar em fermentação no estado solido utilizando casca de cafe como substrato

Tagliari, Cristiane Vanessa 19 December 2003 (has links)
Orientadores: Telma Teixeira Franco, Carlos Ricardo Soccol / Tese (doutorado) - Universidade Estadual de Campinas, Faculdade de Engenharia Quimica / Made available in DSpace on 2018-08-03T19:30:30Z (GMT). No. of bitstreams: 1 Tagliari_CristianeVanessa_D.pdf: 4479697 bytes, checksum: 6be0c025bfea14b198b09f150c93d561 (MD5) Previous issue date: 2003 / Resumo: Avanços na biotecnologia, principalmente na área de tecnologia enzimática e de fragmentações, oferecem oportunidades para a utilização econômica de resíduos agroindustriais. A casca obtida durante o processamento do café por via seca tem sido pouco empregada quando comparada com volume em que é gerada. Este resíduo poderia ser mais utilizado se compostos tóxicos como cafeína e taninos fossem removidos. Fungos filamentosos são capazes de assimilar cafeína e taninos de um meio sintético líquido ou de resíduos de café. Existem poucos trabalhos sobre a detoxificação da casca de café e esta nunca foi relatada com cepas de Rhizopus delemar. A via de degradação da cafeína por este microrganismo e as enzimas envolvidas neste processo também não estão descritas na literatura. O objetivo deste trabaJho foi agregar valor a casca de café por fennentação no estado sólido com R. delemar, investigar a via de degradação da cafeína e caracterizar as enzimas envolvidas neste bioprocesso. As condições de fermentação da casca de café por R. delemar foram otimizadas e os melhores níveis de detoxificação (86% de redução da cafeína e 60% de taninos) foram obtidos em frascos de Erlenmeyer com 75% de umidade inicial, 1O6esporos/g substrato seco, pH 6,5 e 28°C. A cinética do processo fermentativo foi conduzida no biorreator de colunas com as condições otimizadas previamente e indicou que o desenvolvimento do fungo filamentoso e a sua respiração foram relacionados com a degradação de cafeína e de açúcares totais presentes na casca de café. A fase exponencial de crescimento microbiano foi encontrada entre 3 e 5 dias, quando foi detectado máximo consumo de 02 e após a máxima produção das enzimas e degradação da cafeína. Valores máximos de atividade enzimática, 1,8 e 3,3 U/g s.s. para a cafeína e a teofilina demetilase respectivamente, foram obtidos após 2 dias de fermentação em frascos de Erlenmeyer. O extrato enzimático foi estável após estocagem a 2°C e o Km estimado, a temperatura e o pH ótimos foram respectivamente 150J.1M, 30°C e pH 6,5 para a cafeína demetilase e 180J.µM, 30°C e pH 7,4 para a teofilina demetilase. Os resultados mostraram boas perspectivas para a utilização de Rhizopus sp. em processos de detoxificação da casca de café e novas oportunidades poderão surgir para a utilização deste bioproduto e para a aplicação do extrato enzimático obtido neste processo / Abstract: Advances in biotechnology, mainly in the area of enzymes and fermentation technology, offer potential opportunities for economic utilization of agro-industrial residues. The coffee husk obtained during dry processing of coffee has been poorly utilized when compared with the produced volume. Removing the toxics compound as caffeine and tannin, this residue could be more utilized. Filamentous fungi are able to assimilate caffeine and tannins from liquid synthetic media or coffee residue. There are few works about coffee husk detoxification and it was never described with strains of Rhizopus delemar. The caffeine degradation pathway and the enzymes involved in this process have not been described in the literature to. The aim of this work was to improve the nutritive value of coffee husk by solid-state fermentation with R. delemar, to investigate the caffeine degradation pathway and to charactecize enzymes involved in this bioprocess. The conditions of coffee husk fermentation by R. delemar were optimized and the best detoxification levels (86% of caffeine and 60% of tannin reduction) were obtained in Erlenmeyer t1asks with 75% initial moisture, 1O6spores/g dry substrate, at pH 6.5 and 28°C. The kinetic of fermentative process was carried out in packed bed column bioreactor using the conditions previously optimized and showed that the development of filamentous fungi and its respiration was related with caffeine degradation and total sugars presents in coffee husk. The exponential phase of microbial growth was achieved between 3 and 5 days, when was detected maximal 02 consumption and after the maximum production of enzymes and caffeine degradation. The maximum activities, 1.8 and 3.3 U/g d.s. for caffeine and the ophylline demethylase respectively, were achieved at 2 days of fermentation in Erlenrneyer :flasks. The enzymatic extracts were stable after storage at 2°C and the Km estimated, the optimum temperature and pH were respectively 150J.1M, 30°C and pH 6.5 for caffeine demethy1ase and 180J.µM, 30°C and pH 7.4 for theophylline demethy1ase. The results showed good prospects of using Rhizopus sp. for the coffee husk detoxification and would open new opportunities for the utilization of this byproduct and for enzymatic extract application / Doutorado / Desenvolvimento de Processos Químicos / Doutor em Engenharia Química
157

Influência da cafeína na sobrevivência de saúvas Atta sexdens rubropilosa (hymenoptera: Formicidae) e no crescimento in vitro de seu fungo mutualista / Influence of caffeine in the survival of leaf-cutting ants Atta sexdens rubropilosa (Hymenoptera: Formicidae) and to in vitro growth of the mutualistic fungus

Carlos Henrique Miyashira 28 January 2008 (has links)
As formigas cortadeiras (Hymenoptera-Formicidae) estão distribuídas desde o sul dos Estados Unidos até a Argentina. São herbívoros comuns de florestas que coletam material vegetal para cultivar um fungo mutualista específico. São conhecidas pelo seu papel ecológico na aeração do solo, na infiltração da água e na ciclagem de nutrientes. Atividades humanas, como o desmatamento e a agricultura, afetam o ambiente, alterando também o comportamento das saúvas, que acabam atacando os espécimes cultivados. Devido aos prejuízos causados à agricultura, novos inseticidas específicos são necessários. Muitos trabalhos têm sido desenvolvidos usando metabólitos secundários para essa finalidade. Este trabalho tem como objetivo avaliar o efeito da cafeína na mortalidade de Atta sexdens rubropilosa (Forel, 1908) e no crescimento in vitro de seu fungo mutualístico Leucoagaricus gongylophorus (Möller) Singer (Leucocoprineae: Agaricaceae), obtidos de sauveiros mantidos em laboratório. Foram utilizadas quatro concentrações de cafeína, 0,01%, 0,05%, 0,10% e 0,50%. Mortalidade das formigas foi avaliada pelo ensaio de ingestão, acrescentando a cafeína a dietas artificiais sólidas. A cafeína foi incorporada ao meio de cultura para medir a sua influência no crescimento in vitro. Independente das concentrações de cafeína, esse metabólito parece atuar como repelente para a saúvas. A respeito do fungo, quanto maior a concentração de cafeína, menor o crescimento in vitro. Inibição do crescimento foi observada em 0,10% e 0,50% e morte do fungo foi observada em algumas amostras Em conclusão, os resultados sugerem que a cafeína pode ser usada como fungicida, sendo adicionada a iscas que serão coletadas pelas formigas e carregada aos ninhos, causando a redução do fungo e/ou a morte e consequentemente, a morte das formigas. / The leaf-cutting ants (Hymenoptera-Formicidae) are found from south of United States to Argentina. They are common florest herbivorous which collect plant material to feed a specific mutualist fungus. These insects are known by their ecological role at soil aeration, water permeation and nutrient cycling. Human activities, like deforestation and agriculture, affect the environment, affecting the behavior of leaf-cutting ants, which start to attack the crops. Due to crops lost, new specific pesticides are needed. Several researches have been developed using secondary metabolites for this purpose. The present work aimed to evaluate the effect of caffeine at Atta sexdens rubropilosa (Forel, 1908) mortality, and at in vitro growth of the mutualist fungus Leucoagaricus gongylophorus (Möller) Singer (Leucocoprineae: Agaricaceae), collected from laboratory nests. Four caffeine concentrations were tested: 0.01%, 0.05%, 0.10% and 0.50%. Ant\'s mortality was evaluated by ingestion assay, adding caffeine to artificial diets. Caffeine was added to culture medium, to measure its influence on in vitro fungus growth. Despite caffeine concentrations, this compound seems to act as repellent to ants. Concerning to the fungus, the higher the caffeine concentration, the lower the in vitro fungus growth. Growth inhibition was observed at both 0.10% and 0.50% concentrations and death of fungus was observed in some samples. In conclusion, the results suggest that caffeine could be used as fungicide, being added to baits which could be collected by ants and carried to the nests, causing fungus reduction and/or death and consequently, the death of the nests.
158

Možnosti ovlivnění vstřebávání kofeinu z kolových nápojů / Influencing of caffein absorption from cola-type beverages

Osecká, Karolína January 2014 (has links)
This diploma thesis was focused on basic physicochemical properties of caffeine and investigation of the interaction between the polysaccharide sodium hyaluronan (HA), pectin (PEC) or lignohumate (HUM) and the alkaloid caffeine (CAF). The reason why this thesis was focused on study of aqueous solutions of hyaluronan or pectin with caffeine is that the presence of polysaccharide- caffeine complex could be beneficial for slowing the absorption of caffeine. In the theoretical part of the diploma thesis there is described a group of alkaloids, which caffeine belongs to and also polysaccharides hyaluronic acid and pectin. The most attention has been paid to caffeine, its properties and effects on the human organism. This diploma thesis also deals with non-alcoholic beverages with caffeine, 4-methylimidazole, and phosphoric acid. The last chapter of the theoretical part is dedicated to fluorescence spectroscopy. In the experimental part of this work I deal with the basic properties of caffeine and interaction between the caffeine and selected polysaccharides or lignohumate. At first, the chemical and physical properties of caffeine were determined. Based on these results the interaction of caffeine and hyaluronan or pectin was studied by using the fluorescence and absorbance. The HA of molecular weight of 1,7 MDa and pectin from citrus fruits were chosen for the study of the interaction with the caffeine. These two substances were mixed with the caffeine of concentration contained in Coca-Cola. The results of interaction that would lead to the influence of the emission or absorption properties of caffeine, were not proved. As a part of the work there was determined how pectin behaves in strongly acidic solution and then there was monitored the pH, conductivity and solubility of caffeine in water by using thermogravimetry and visual experiments. The obtained results of the interaction of hyaluronan-caffeine, pectin caffeine or caffeine-lignohumate can be used for description of the behavior of caffeine in the presence of selected polysaccharides and natural organic substance.
159

The Toxicology of Chemical Interactions During Pregnancy in the Mouse: Caffeine and Phenytoin

Skalko, R. G., Poche, P. D., Kwasigroch, Thomas E. 14 February 1984 (has links)
The toxic interaction of caffeine and phenytoin during pregnancy was investigated in mice of the ICR strain on E10 of gestation. Caffeine, over a range of dosages, showed limited embryotoxic activity. Phenytoin was also weakly teratogenic and dosages needed to elicit embryotoxicity were accompanied by a significant increase in maternal lethality. Pretreatment with caffeine enhanced phenytoin-induced toxicity and teratogenicity and these observations confirm that caffeine has the ability to function as a coteratogen. Pretreatment with phenytoin produced a significant increase in maternal lethality following caffeine administration but no co-teratogenic effect. It is suggested that these results are the consequence of a yet undefined interaction at critical receptor sites in the maternal-embryo unit.
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Potential Toxicity of Caffeine When Used as a Dietary Supplement for Weight Loss

Pendleton, Morgan, Brown, Stacy, Thomas, Christan, Odle, Brian 01 December 2012 (has links)
Many dietary supplements being promoted for weight loss contain caffeine-or ephedra-related alkaloids to increase energy and suppress appetite. People may be unaware that supplements can contain caffeine, even if caffeine is not listed as an ingredient. Commonly used herbal dietary supplement ingredients, such as guarana, are natural sources of caffeine. Additions of these natural sources of caffeine to dietary supplements have increased in recent years. We describe a case of possible caffeine-induced seizure in a patient taking an over-the-counter weight loss supplement. A previously healthy 38-year-old female experienced blurring of vision and a new onset grand mal seizure. The patient had a 2-month history of taking the dietary supplement, Zantrex-3™. Zantrex-3™ is advertised as a weight loss supplement, which may provide rapid weight loss and extreme energy in one "power packed pill." Zantrex-3™ is a proprietary blend containing niacin, caffeine, and various herbs. After presenting to the hospital emergency room, the patient's chemistry panel, with the exception of potassium (2.9 mEq/L), was within normal limits. An electroencephalogram (EEG) was unremarkable. The magnetic resonance imaging (MRI) showed possible atrophy in the right frontal lobe. Findings from follow-up MRI and EEG ordered as an outpatient were within normal limits. After discontinuation of Zantrex-3™, the patient has experienced no further seizure activity.

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