Ce travail a consisté, dans un premier temps, à extraire et à identifier les flavonoïdes majeurs contenus dans les feuilles de Nitraria retusa et à évaluer leurs activités biologiques. Quatre flavonoïdes ont été identifiés dans les extraits et les fractions obtenus : l’isorhamnétine, l’isorhamnétine-3-O-glucoside et les deux isomères isorhamnétine-3-O-rutinoside et isorhamnétine-3-O-robinobioside. L’étude des activités biologiques des extraits et des fractions de N. retusa a permis d’établir une relation linéaire entre leur teneur en flavonoïdes et leurs activités antioxydantes et antiprolifératives, les milieux les plus riches présentant les activités les plus importantes. Ces activités dépendent également de la nature des flavonoïdes présents ; ainsi, la très forte activité d’inhibition de la xanthine oxydase relevée pour la fraction au chloroforme et sa grande capacité à piéger le radical DPPH ont été attribuées à sa teneur élevée en isorhamnétine, flavonoïde aglycone présentant une grande analogie structurale avec la quercétine, molécule bien connue pour ses activités antioxydantes. Dans un deuxième temps, l’acylation enzymatique de l’isoquercitrine, flavonoïde modèle, et de l’isorhamnétine-3-O-glucoside a été étudiée pour tenter d’améliorer leurs propriétés. L’acylation enzymatique de l’isoquercitrine par des esters éthyliques d’acides gras de différentes longueurs de chaîne, catalysée par la lipase B de Candida antarctica, a montré que les performances de la réaction sont inversement proportionnelles à la longueur de la chaîne du donneur d’acyle. Des résultats similaires ont été obtenus lors de l’acylation de l’isorhamnétine-3-O-glucoside. Les activités des esters d’isoquercitrine et d’isorhamnétine-3-O-glucoside ont été évaluées et comparées à celles des flavonoïdes non acylés. Les esters ont montré des activités antiprolifératives vis-à-vis de cellules Caco2 et d’inhibition de la xanthine oxydase plus importantes que celles des molécules d’origine. Finalement, ce travail a permis d’apporter des éléments de compréhension de la relation structure-activité de flavonoïdes et de leurs dérivés acylés / The present work firstly consisted in studying the extraction and the identification of major flavonoids contained in Nitraria retusa leaves and evaluating their biological activities. Four flavonoids were identified in extracts and fractions: isorhamnetin, isorhamnetin-3-O-glucoside and the two isomers isorhamnetin-3-O-rutinoside and isorhamnetin-3-O-robinobioside. The evaluation of the biological activities of extracts and fractions of N. retusa allowed to establish a linear relationship between their antioxidant and antiproliferative activities and their total flavonoids content, the most enriched exhibiting the highest activities. The nature of the flavonoids present in the extracts and fractions was shown to be important too. Thus, the strong xanthine oxidase inhibition activity and the high DPPH radical scavenging capacity observed for the chloroform fraction can be attributed to its high content in the aglycone flavonoid isorhamnetin, a structural analogue of quercetin which is well known for its antioxidant activities. In a second part, the enzymatic acylation of isoquercitrin as a model compound and isorhamnetin-3-O-glucoside was studied in order to improve their properties. The enzymatic acylation of isoquercitrin by fatty acid ethyl esters of different chain lengths, catalyzed by the lipase B of Candida antarctica, showed that the performance of the reaction is inversely proportional to the acyl donor chain length. Similar results were obtained when acylating the isorhamnetin-3-O-glucoside. The activities of isoquercitrin and isorhamnetin-3-O-glucoside esters were determined and compared to that of initial flavonoids. Esters exhibited higher antiproliferative towards Caco2 cells and xanthine oxidase inhibition activities than original compounds. Finally, this work led to a better understanding of the structure-activity relationship of flavonoids and their acylated derivatives

Inputs from terrestrial habitats to aquatic habitats are important for structuring aquatic communities. Terrestrial producer diversity in the tropics may decline due to anthropogenic causes. I investigated how tree diversity affects aquatic communities. We used leaves from three timber-producing species (Dalbergia retusa, Pachira quinata, and Tectona grandis) to test the effects of leaf litter species composition and richness on invertebrate aquatic communities in Gamboa, Panama. We quantified macroinvertbrate species richness and abundances, leaf litter mass loss, and dissolved carbon to nitrogen ratios (C:N) after 4 weeks. We found that litter types differed in breakdown and C:N. Tectona grandis had lower dissolved C:N than both native species and supported the fewest number of invertebrates. C:N ratios declined with increasing litter diversity; however breakdown was not affected by litter richness. Mosquito abundance increased with litter species richness. Results of this study highlight the importance of diverse detritus in structuring aquatic treehole communities.

Made available in DSpace on 2015-04-11T13:38:44Z (GMT). No. of bitstreams: 1 Vanessa.pdf: 3684235 bytes, checksum: 9a9ca68627cdbe2a70c583d22130850f (MD5) Previous issue date: 2012-02-27 / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior / In this work was realized a phytochemical study and evaluations of extracts and phases of Andira retusa (Fabaceae) regarding activities such as antioxidant, cytotoxic and antimicrobial. This is the first chemical and biological study with this species. There was realized two collects of vegetal material, whose extracts were analyzed by TLC. From chromatographic fractionation of dichloromethane phase of barks methanolic extract resulted in the isolation of lupeol and the mixture of β-sitosterol and stigmasterol. There were also fractionated: the flowers dichloromethane extract; the dichloromethane and ethyl acetate phases from the barks dichloromethane extract and the ethyl acetate phase from the barks methanolic extract. The NMR 1H spectrum of these extracts and phases showed signs characteristic of terpenes (possibly steroids), aromatic compounds (likely flavonoids and chalcones) and aldehydes groups were observed, but were not possible to isolate the compounds to realize the structural identification. The barks, leaves and branches methanolic extracts, as well as the ethyl acetate and butanolic phases from the barks dichloromethane and methanolic extracts, showed a major antioxidant potencial against free radical DPPH. The extracts of 1 DCM Flower and 2 MeOH Bark showed high cytotoxic potential against Brine shrimp Lethality and on cells L929. All extracts showed low activity against Aeromonas hydrophila. However, when analyzed for antimicrobial activity against other microorganisms (Staphylococcus aureus, Escherichia coli and Pseudomonas aeruginosa), there were observed the activity for the extracts: 1 DCM Branches (1000 μg/mL), 1 MeOH Leaves (1000 e 500 μg/mL) and 1 MeOH Flowers (1000 μg/mL) against S. aureus, 1 MeOH Leaves (1000 μg/mL) against all three microorganisms assayes and 1 DCM Flowers (1000 μg/mL) against S. aureus and E. coli. Of all phases tested, only phase 2 CaM 3.1 (1000 μg/mL) showed antimicrobial activity against S. aureus. The results of biological activities showed that many of the phases whose demonstrated biological activities came from inactive or with low activity crude extracts, which indicated the importance of fractionating biogically active extract as well as those chemically intere / Neste trabalho foi realizado o estudo fitoquímico e avaliações dos extratos e fases de Andira retusa (Fabaceae) quanto às atividades: antioxidante, citotóxica e antimicrobiana. Este é o primeiro estudo químico e biológico com esta espécie. Foram realizadas duas coletas de material vegetal, e extratos obtidos dos mesmos foram analisados por CCD. Do fracionamento cromatográfico da fase diclorometânica do extrato metanólico das cascas foi possível isolar o lupeol e a mistura de -sitosterol e estigmasterol. Foram também realizados os fracionamentos: do extrato diclorometânico das flores e das fases diclorometânica e acetato de etila obtida do extrato diclorometânico das cascas e da fase acetato de etila obtida extrato metanólico das cascas. Os espectros de RMN de 1H dos extratos e fases mostraram sinais característicos de terpenos (possivelmente esteroides), compostos aromáticos (possivelmente flavonoides e chalconas) e grupos aldeídos, mas não foi possível isolar as substâncias para realizar a identificação estrutural. Os extratos metanólicos das cascas, das folhas e dos galhos, assim como as fases de polaridade intermediária e mais polares dos extratos diclorometânico e metanólicos das cascas, apresentaram um maior potencial antioxidante frente ao radical livre DPPH. Dos extratos e fases testados para atividade citotóxica frente à Artemia salina e sobre as células L929, os que tiveram resultados significativos foram os extratos diclorometânico das flores da 1ª coleta e metanólico das cascas da 2ª coleta. Todos os extratos apresentaram baixa atividade contra Aeromonas hydrophila. No entanto, frente a outros micro-organismos (Staphylococcus aureus, Escherichia coli e Pseudomonas aeruginosa) foram ativos os extratos: 1 Galho DCM (1000 μg/mL), 1 Folha MeOH (1000 e 500 μg/mL) e 1 Flor MeOH (1000 μg/mL) contra S. aureus, 1 Folha MeOH (1000 μg/mL) contra os três micro-organismos e 1 Flor DCM (1000 μg/mL) contra S. aureus e E. coli. Das fases testadas, somente a fase 2 CaM 3.1 (1000 μg/mL) apresentou atividade sobre S. aureus. Os resultados das atividades biológicas mostraram que várias das fases que apresentaram atividades provinham de extratos brutos inativos ou com baixa atividade, o que indica a importância do fracionamento de extratos biologicamente ativos e daqueles quimicamente interessantes.

Submitted by Emanoel Martins Filho (emanoelfilho@ufba.br) on 2016-09-12T17:23:39Z No. of bitstreams: 1 Dissertação Ravena Nascimento.pdf: 6552693 bytes, checksum: 2ae939c27305452b9886c764511a027c (MD5) / Approved for entry into archive by Patricia Barroso (pbarroso@ufba.br) on 2016-09-13T20:33:18Z (GMT) No. of bitstreams: 1 Dissertação Ravena Nascimento.pdf: 6552693 bytes, checksum: 2ae939c27305452b9886c764511a027c (MD5) / Made available in DSpace on 2016-09-13T20:33:18Z (GMT). No. of bitstreams: 1 Dissertação Ravena Nascimento.pdf: 6552693 bytes, checksum: 2ae939c27305452b9886c764511a027c (MD5) / As interações metabólicas e de sinalização entre neurônios e células gliais são necessárias para o desenvolvimento e manutenção das funções e estruturas cerebrais e para neuroproteção, o que inclui a proteção contra ataques químicos. Os astrócitos são essenciais para a desintoxicação cerebral e apresentam um eficiente e específico sistema enzimático citocromo P450. Embora plantas do gênero Crotalária (Fabaceae, Leguminosae) sejam utilizadas na medicina popular, estas plantas são também consideradas tóxicas e podem causar danos a animais domésticos bem como problemas à saúde humana. Estudos em animais mostraram casos de intoxicação por plantas desse gênero, que induziram danos ao sistema nervoso central. Esta descoberta tem sido atribuída aos efeitos tóxicos do alcaloide pirrolizidinico (AP), monocrotalina (MCT). O envolvimento dos sistemas enzimáticos hepáticos P450 no metabolismo e toxicidade pulmonar da MCT foi elucidado, mas pouco se sabe sobre os mecanismos envolvidos na bioativação destes sistemas e a sua relação direta sobre a toxicidade no cérebro. Esta revisão apresenta os principais aspectos toxicológicos do gênero Crotalária que são estabelecidos na literatura e os resultados recentes que descrevem os mecanismos envolvidos nos efeitos neurotóxicos da MCT, extraída de Crotalária retusa, e sua interação com os neurônios em astrócitos isolados. / The metabolic interactions and signaling between neurons and glial cells are necessary for the development and maintenance of brain functions and structures and for neuroprotection, which includes protection from chemical attack. Astrocytes are essential for cerebral detoxification and present an efficient and specific cytochrome P450 enzymatic system. Whilst Crotalaria (Fabaceae, Leguminosae) plants are used in popular medicine, they are considered toxic and can cause damage to livestock and human health problems. Studies in animals have shown cases of poisoning by plants from the genus Crotalaria, which induced damage to the central nervous system. This finding has been attributed to the toxic effects of the pyrrolizidine alkaloid (PA) monocrotaline (MCT). The involvement of P450 enzymatic systems in MCT hepatic and pulmonary metabolism and toxicity has been elucidated, but little is known about the pathways implicated in the bioactivation of these systems and the direct contribution of these systems to brain toxicity. This review will present the main toxicological aspects of the Crotalaria genus that are established in the literature and recent findings describing the mechanisms involved in the neurotoxic effects of MCT, which was extracted from Crotalaria retusa, and its interaction with neurons in isolated astrocytes.