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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.
21

Efeito induzido pelo vírus Y da batata (Potato virus Y) no metabolismo secundário do camapu (Physalis angulata L.) / Potato virus Y induced effect in Physalis angulata L. secondary metabolism

Nagai, Alice 23 November 2012 (has links)
Physalis angulata L. (Solanaceae), popularmente conhecida como camapu ou balãozinho, é uma espécie que vem ganhando importância econômica em decorrência de suas atividades biológicas, como citotóxica, antibacteriana e anti-inflamatória. Dentre os diversos metabólitos secundários conhecidos para esta espécie, destacam-se os flavonoides e alcaloides. É amplamente difundido que o metabolismo secundário das plantas pode ser alterado por fatores bióticos e abióticos. Nesse sentido, esse trabalho objetivou destacar a influência do Potato virus Y, estirpe O (PVYO), isolado de camapu, no metabolismo secundário, avaliando as quantidades e os perfis de flavonoides e alcaloides também em plantas de camapu infectadas. A infecção viral foi induzida em plantas obtidas por sementes, os metabólitos foram extraídos a partir de folhas, foram analisados em CLAE e CG-EM e comparados com aqueles provenientes de plantas sadias. Não foram observadas diferenças qualitativas nos perfis tanto dos flavonoides quanto dos alcaloides. Por outro lado, houve diminuição no teor de flavonoides totais nas plantas infectadas na infecção sistêmica. Além disso, houve aumento significativo do derivado de atropina nas plantas infectadas em comparação com os demais tratamentos. Dessa forma, sugerimos que a infecção induzida pelo PVYO em plantas de camapu teve maior impacto na via das substâncias nitrogenadas em relação às fenólicas / Physalis angulata L. (Solanaceae), popularly known as \"camapu\" or \"balãozinho\", has become economically important due to its biological activities, such as cytotoxic, antibacterial and anti-inflammatory. Among the secondary metabolites, flavonoids and alkaloids have already been described for this species. Secondary metabolism can be influenced by both biotic and environmental agents. The main goal of this work was to analyze the influence of Potato virus Y (PVYO) on the secondary metabolism of infected \"camapu\" plants, evaluating total amount and profiles of flavonoids and alkaloids. Viral infection was induced in plants obtained from seeds. The compounds were extracted from leaves, analyzed in HPLC and GC/MS and compared with those from healthy plants. There were no qualitative differences between healthy and infected plants concerning to alkaloid and flavonoid profiles. On the other hand, it was noticed a lower flavonoid concentration in the systemic infection of infected plants. An increase of an atropine derivative was observed in infected plants. In conclusion, according to the results we propose that the PVYO induced infection in plants of \"camapu\" had stronger impact on the nitrogenous compounds than on phenolics
22

Isolamento e identificação de metabólitos produzidos por linhagens de microrganismos do ambiente marinho / Isolation and identification of metabolites produced by strains of microorganisms from the marine environment

Karen de Jesus Nicácio 21 July 2017 (has links)
A investigação de produtos naturais tem sido cada vez mais direcionada para o estudo de microrganismos, com destaque para aqueles do ambiente marinho. Neste trabalho foram estudadas linhagens bacterianas isoladas de tecidos da esponja Arenosclera brasiliensis, como parte de um estudo que tinha o objetivo de encontrar novas moléculas bioativas. O cultivo da linhagem bacteriana Pseudovibrio denitrificans Ab134 permitiu o isolamento e identificação de três compostos derivados de dibromotirosina, a fistularina-3 (26), o ácido verongidoico (27) e a 11-hidroxiaerotionina (28). Outros cinco compostos derivados de dibromotirosina foram detectados, em frações ainda impuras, através de análises por CLUE-qTOF e tiveram suas estruturas propostas de acordo com os íons de fragmentação observados no espectro de EMAR: aerotionina (29), um éster do ácido purpurocerático B (30), purealidina L (31) e aplisinamisina II (32). Este é o primeiro relato da produção dos derivados de dibromotirosina a partir de uma linhagem bacteriana e representa um forte indício de que tais compostos, comumente isolados de esponjas, são na verdade produzidos pela microbiota associada destes animais. O cultivo da linhagem fúngica Biatriospora sp. permitiu o isolamento e identificação de nove compostos diterpênicos da classe das fomactinas, sendo seis deles inéditos. As fomactinas são conhecidas por apresentarem potente atividade como inibidoras de receptores do PAF. As fomactinas S, P, U e I apresentaram bons resultados na inibição da ligação do PAF aos seus receptores. As fomactinas S e P foram também avaliadas em ensaio de re-população tumoral pós irradiação e foram capazes de inibir o fenômeno de re-população em concentração molar equivalente a antagonistas comerciais. Tal resultado sugere que a associação da radioterapia com antagonistas do PAF-R pode ser uma nova e eficiente alternativa terapêutica para inibição do crescimento de tumores. / Research on natural products is increasingly focusing on the study of microorganisms, especially those from the marine environment. In the present investigation, bacterial strains isolated from tissues of the sponge Arenosclera brasiliensis were studied in order to find new bioactive molecules. Cultivation of the bacterial strain P. denitrificans allowed the isolation and identification of three dibromotyrosine-derived compounds: fistularin-3 (26), verongidoic acid (27) and 11-hydroxyaerothionin (28). Another five dibromotyrosine-derived compounds were detected in still impure fractions by UPLC-qTOF analysis and had their structures proposed according to the fragmentation ions observed in the HRMS spectrum: aerothionin (29), the methyl ester of purpuroceric acid B (30), purealidin L (31) and aplisinamysin II (32). This is the first report of the production of dibromotyrosine derivatives by a bacterial strain and represents a strong indication that such compounds, commonly isolated from sponges, are actually produced by the associated microbiota of these animals. Cultivation of the fungal strain Biatriospora sp. allowed the isolation and identification of nine fomactin diterpenes, six of wich are new. Fomactins are known as inhibitors of PAF receptors. Fomactins S, P, U and I have shown good results in inhibiting the binding of PAF to their receptors. The fomatins S and P were also evaluated in the post-irradiation tumor re-population assay and were able to inhibit the re-population phenomenon at micromolar concentration equivalent to commercial antagonists. Such a result suggests that the association of radiotherapy with PAF-R antagonists may be a new and efficient therapeutic alternative in tumors.
23

Chemical and Biological Investigation of the Antarctic Red Alga <em>Delisea pulchra</em>

Nandiraju, Santhisree 09 July 2004 (has links)
Our interest in the red alga Delisea pulchra (=D.fimbriata) (Greville) Montagne 1844 (Rhodophyceae, Bonnemaisoniales, Bonnemaisoniaceace) was stimulated by its activity in the biosssays done at Wyeth Pharmaceuticals. Halogenated compounds from D. pulchra interfere with Gram-negative bacterial signaling systems, affect the growth of Gram-positive bacteria, inhibit quorum sensing and swarming motility of marine bacteria (inhibit bacterial communication). They also inhibit surface colonization in marine bacteria and exhibit antifouling properties against barnacle larvae and macroalgal gametes. Chemical investigation of D.pulchra collected near Palmer Station, Antarctica yielded three new dimeric halogenated furanones, pulchralide A-C (41-43), along with previously reported fimbrolide (21), acetoxyfimbrolide (22), hydroxyfimbrolide (23) and halogenated ketone 40. The reported Compounds were characterized by comparison of their 1H and 13C NMR data with that previously published. Pulchralide A-C were characterized by both 1D (1H NMR, 13C NMR, DEPT, 1H-1H COSY) and 2D (gHMQC, gHMBC) NMR techniques, supported by HREIMS/HRESIMS data. The absolute stereochemistry of Pulchralide A was determined by a single crystal X-ray analysis. Significant antimicrobial activity was observed in acetoxyfimbrolide (22) and hydroxyfimbrolide (23), where as pulcharlide A (41) and fimbrolide (21) were weakly active.
24

Studies on Secondary Metabolites from the Bamboo Coral Isis hippuris

Chen, Wei-Hua 05 September 2011 (has links)
Previous studies on the secondary metabolites of Formosan octocoral Isis hippuris were collected only at Green Island. In the course of our studies on secondary metabolites from marine organisms, the acetone-solubles of the Formosan octocoral Isis hippuris collected at Orchid Island has led to the isolation of eleven polyoxygenated steroids (1¡V11), along with two known compounds (12 and 13). The structures of these compounds were determined on the basis of their spectroscopic and physical data, including NMR, IR, MS, etc. The cytotoxicity against of A-549 (human lung epithelial carcinoma), HT-29 (human colon adenocarcinoma), and P-388 (mouse lymphocytic leukemia) cells, and anti-HCMV (human cytomegalovirus) activity of metabolites 1¡V13 were evaluated. Compounds 12 and 13 displayed cytotoxicity against P-388 cell line with ED50 values of 3.2 and 3.6 £gg/mL, respectively. Compound 12 exhibited cytotoxicity against A-549 cell line with an ED50 value of 3.8 £gg/mL. Compound 8 exhibit inhibitory activity against HCMV, with EC50 values of 2.0 £gg/mL.
25

Chemical Constituents of the Formosan Soft Coral Nephthea chabrolii

Puu, Shyh-Yueh 10 September 2012 (has links)
Numerous bioactive secondary metabolites including sesquiterpenoids,diterpenoids, meroditerpenoids, and steroids have been isolated from the soft corals of the genus Nephthea. In order to search for novel bioactive substances from marine organisms, we have investigated the secondary metabolites of the organic extract of the soft coral Nephthea chabrolii collected at San-Hsian-Tai. Chromatographic fractionation of the acetone-soluble has led to the isolation of four 19-oxygenated steroids 1¡V4 and two 19-norergosterols 5, 6, along with twelve known compounds 7¡V18. The structures of these compounds were determined on the basis of their spectroscopic analysis data (1H NMR, 13C NMR, 1H¡V1H COSY, HSQC, HMBC, NOESY, IR, and HRESIMS), physical data and compared with the literature data. The cytotoxicity against of A-549 (human lung epithelial carcinoma), HT-29 (human colon adenocarcinoma), and P-388 (mouse lymphocytic leukemia) cells, and anti-HCMV (human cytomegalovirus) activity of compounds 1¡V6 were evaluated. Metabolites 1¡V6 displayed cytotoxicity against P-388 cell line with ED50 values of 0.93, 1.05, 1.20, 1.74, 1.19, 1.19 £gg/mL. However, none of them exhibited inhibitory activity against HCMV (human cytomegalovirus).
26

Studies on Secondary Metabolites of the Formosan Gorgonian Isis hippuris and Virgularia juncea

Chen, Shin-Pin 27 July 2001 (has links)
Abstract In our continuing studies on the chemical constituents of Taiwanese octocorals, the gorgonian coral Isis hippuris and the sea pen coral Virgularia juncea, which were collected from the coast of Green Island and Peng-Hung Islands, respectively, have been the subjects of our investigations. Six compounds, including two new steroids, hippuristerones A and E (1 and 2), along with three known steroids 3£]-hydroxy-5£\-pregnan -20-one (3), prenga-4-ene-3,20-dione (4), prenga-1,4-diene-3,20-dione (5) and a known sesquiterpene subergorgic acid (6) were isolated from I. hippuris. Four compounds, incoulding a new sesquterpene, junceol A (7) and two known diterpenoids, sclerophytin A (8), cladiellisin (9) and a known steroid 24-methylenecholesterol (10) were isolated from V. juncea. The structures of above isolates were determined by physical (mp and optical rotation) and extensive spectral (UV, IR, MS, HRMS, 1D and 2D NMR) analysis and by comparison with the related physical and spectral data from other known compounds. The structure, including the relative configuration of hippuristerone A (1) was further confirmed by a single-crystal X-ray analysis.Furthermore, the relative configuration of hippuristerone E (2) was supported by the chemical dynamics calculations.
27

Molecular Mapping and Characterization of Phenylpropanoid Pathway Genes in Common Bean (Phaseolus vulgaris L.)

Yadegari, Zeinab 06 September 2013 (has links)
Common bean is a nutritionally and economically important food crop and a major source of dietary protein in many developing countries throughout the world. Seed coat colour and size in this crop are the main factors determining its marketability in different parts of the world. Flavonoid compounds that are responsible for seed coat colour in beans have been shown to have anti-oxidant, anti-proliferative, anti-tumor, anti-inflammatory, and pro-apoptotic activities. They also may enhance the resistance of beans to pest and disease. A better understanding of the relationships between seed coat colour and flavonoid metabolism in the seed coat may help breeders to select for more nutritionally-beneficial bean varieties. The objective of this research was to test the hypothesis that the genes determining colour in beans are structural and regulatory genes of the phenylpropanoid pathway. The map positions of phenylpropanoid genes were determined in two recombinant inbred populations. Segregation patterns of 18 phenylpropanoid pathway genes in the BAT93 × Jalo EEP 558 RIL population and five phenylpropanoid pathway genes in OAC Rex × SVM Taylor were used to place them on the linkage maps for these populations. Five out of 18 genes were mapped within 2-17 cM of colour gene loci in the BAT93 × Jalo EEP 558 RIL population. The sequences of central genes of the phenylpropanoid pathway were determined by sequencing 6 BAC clones selected with probes for two PAL genes, two CHS genes, DFR, and Myb. The functional annotations of the BAC clones were determined and the similarities between bean phenylpropanoid genes and their corresponding orthologs in other plant species were investigated. A recently developed approach of whole genome sequence comparison was utilized to compare the microsynteny of the sequenced BAC clones with regions of the soybean genome. The physical locations of BAC clones were verified on the bean genome and their counterpart locations on the soybean genome were confirmed. The results agreed with previous studies that indicated that bean genome segments have two homologous segments in soybean and confirmed the high degree of microsynteny that is shared between bean and soybean.
28

Metabolic Engineering of Isoflavonoid Biosynthesis in Tobacco and White Clover.

Franzmayr, Benjamin January 2011 (has links)
Isoflavonoids are a class of plant secondary metabolites which have multiple biological roles in plants as pest feeding deterrents, phytoalexins and signals to rhizobial microbes. Some isoflavonoids, or their breakdown products, are estrogenic when ingested by animals, and pastures with high levels of the isoflavonoid formononetin can cause sterility in ewes. White clover has low levels of isoflavonoids and is susceptible to pests like the clover root weevil. The overall aim of this project was to test whether isoflavonoids could be manipulated in white clover through metabolic engineering. The genes of the key isoflavonoid biosynthesis enzymes have been cloned from a range of legumes and three major genes, chalone reductase (CHR), isoflavone synthase (IFS) and isoflavonoid O-methyltransferase (IOMT), were cloned from white clover in this study. The white clover IFS2_12 gene was expressed in transgenic tobacco. Genistein, an isoflavonoid that is not naturally present in tobacco, was detected in the IFS-expressing tobacco, thus confirming the functionality of the IFS2_12 gene. Tobacco plants were transformed with ANT1, a transcription factor that induces the production of anthocyanins that share precursors with the isoflavonoid biosynthesis pathway. When IFS was expressed in red tobacco leaves, where anthocyanin biosynthesis was occurring, the levels of genistein were greater than in anthocyanin-free green leaves. White clover was transformed to overexpress the cloned IFS2_12 gene and some transformants had greater levels of IFS gene expression, up to 12.9 times the average wild type level. However, these transformants did not produce formononetin levels greater than the wild-type. A gene fusion of alfalfa chalcone isomerase (CHI), which produces the precursors naringenin and liquiritigenin, and soybean IFS, which converts the precursors to genistein and daidzein, respectively, was received from the Noble Foundation. Transgenic white clover plants expressing IFS/CHI were produced using a novel method that also regenerated wild-type clones of the transgenic plants. When compared with their wild-type clones, two IFS/CHI transformants produced higher levels of formononetin, thus supporting the suggestion that isoflavonoid levels can be increased in white clover through overexpression of isoflavonoid biosynthesis genes.
29

Ecological patterns in plant defence chemistry and herbivore responses in natural populations of Brassica oleracea

Goodey, Nicole Ann January 2015 (has links)
Relationships between two taxonomic kingdoms; plants and herbivorous insects, are hypothesized to be a major zone of interaction for generating current day biodiversity; and coevolutionary processes between these intricately linked organisms are hypothesized to maintain diversity in plant secondary chemistry. These metabolites play a key role in plant defence against herbivory and a high degree of intraspecific variation is observed at multiple ecological scales. However, the nature of selection maintaining variation in plant defence profiles is still a major question in evolutionary biology and ecology, and progress towards a deeper understanding is hampered by a lack of studies that take into account ecological context and the multivariate nature of plant defence phenotypes. In this thesis, I employ sophisticated chemical analysis techniques to identify a suite of glucosinolate secondary chemicals, representing different biosynthetic pathways, in the wild cabbage, Brassica oleracea, in natural populations in the UK. I used model-based cluster analysis to explore patterns of association between individual glucosinolates, predicting that as simultaneous resource allocation to multiple defences is likely to be constrained; negative associations between defensive traits should be observed. However, results revealed positive associations between glucosinolates. Therefore co-expression of multiple defences may not be costly for this species. Using this information in conjunction with herbivore surveys and experiments, I show that this mixture has the potential to shape patterns of herbivore abundance and host plant utilization: species-specific responses to variation in glucosinolate phenotypes are discovered at various ecological scales. Thus there is the potential for differential selection on plant chemotypes though species-specific attractions and aversions. By conducting fine scale experiments with herbivore species, I also found that glucosinolate variation has an impact on the counter-adaptations that some brassica specialists have evolved: in order to optimally defend against their own natural enemies, Brevicoryne brassicae aphids sequestering glucosinolates from their host plants must do so selectively, and must choose plants whose chemical profile best matches this behaviour. These findings show that glucosinolate profiles may be under natural selection by herbivores in wild populations, and that reciprocal evolution between these plants and their specialists may continue to promote diversity in secondary metabolites. Together these results highlight the complexity inherent in plant-insect interactions, the importance of field studies and generate a wealth of testable hypotheses for future work.
30

Cytostatický efekt nostatinu A a jeho přírodních analogů na buněčnou linii HeLa

VICKOVÁ, Kateřina January 2017 (has links)
Cyanobacterial secondary metabolites are a rich source of bioactive compounds with potential utilization in pharmacology. The aim of this study was to evaluate the effect of the novel compound nostatin A isolated from the cyanobacterium Desmonostoc muscorum. Project was focused on the extraction, purification and characterization of the cytostatic effect caused by this novel compound and its naturally occurred structural analogues. The cytostatic activity of nostatin A and its analogs was evaluated in HeLa cell line. Experiments based on microscopy, flow cytometry and HPLC-HRMS techniques were performed in order to clarify the cytostatic effect of nostatin A in HeLa cells and its mechanism of the action.

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