• Refine Query
  • Source
  • Publication year
  • to
  • Language
  • 10
  • 6
  • 3
  • Tagged with
  • 21
  • 21
  • 7
  • 7
  • 5
  • 4
  • 4
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 3
  • 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.
1

Bioactive natural products from nature

Brastianos, Harry Charilaos 11 1900 (has links)
Bioassay guided fractionation of a crude extract of the marine sponge Neopetrosia exigua resulted in the first reported isolation of exiguamines A and B. These pyrroloquinone alkaloids have an unprecedented hexacyclic skeleton that has not been previously encountered in natural products. Biological studies have identified exiguamine A as a potent in vitro inhibitor of the enzyme indoleamine-2,3-dioxygenase (IDO). IDO is an enzyme expressed by tumor cells to evade the immune system. Inhibitors against this enzyme may allow the immune system to attack cancer cells, making this enzyme a potential drug target for anti-cancer agents. Investigation of the crude extract of a Bacillus sp. collected in Dominica led to the isolation of the known diketopiperazine cyclo(S-Val-S-Phe) (3.9). In vitro biological studies revealed that cyclo(S-Val-S-Phe) is able to promote neurite outgrowth, even in the presence of physiological inhibitors. In vivo studies have shown that cyclo(S-VaI-S-Phe) is able promote sprouting in serotonergic and adrenergic axons. Synthesis of the other three diastereomers led to the discovery that cyclo(R-Val-R-Phe) is also an in vitro activator of axonal outgrowth. Inhibitors of the G2 checkpoint are able to increase the cytotoxicity of DNA damaging chemotherapeutics. Bioassay guided fractionation of an extract of the South American plant Duguetia odorata led to the isolation of the G2 checkpoint abrogator, oliveroline. This investigation also led to the isolation of the previously unreported alkaloid N-methylguatterine, and the known alkaloids dehydrodiscretine and pseudopalmatine. Chemical investigation of the marine sponge Myrmekioderma granulatum led to the isolation of the new compounds abolenone and myrmekioside C, as well as the known compounds curcudiol, curcuphenol, abolene and sesquiterpenoid. Biological studies of these compounds revealed that curcudiol is a ligand of the sex hormone-binding globulin. This protein is involved in transporting and regulating the concentration of steroids such as testosterone and estradiol. Many pathological conditions have a lower plasma concentration of these steroids. Ligands to SHBG can release steroids into the blood, so this protein is a potential drug target to treat conditions where a hormone insufficiency is present.
2

Bioactive natural products from nature

Brastianos, Harry Charilaos 11 1900 (has links)
Bioassay guided fractionation of a crude extract of the marine sponge Neopetrosia exigua resulted in the first reported isolation of exiguamines A and B. These pyrroloquinone alkaloids have an unprecedented hexacyclic skeleton that has not been previously encountered in natural products. Biological studies have identified exiguamine A as a potent in vitro inhibitor of the enzyme indoleamine-2,3-dioxygenase (IDO). IDO is an enzyme expressed by tumor cells to evade the immune system. Inhibitors against this enzyme may allow the immune system to attack cancer cells, making this enzyme a potential drug target for anti-cancer agents. Investigation of the crude extract of a Bacillus sp. collected in Dominica led to the isolation of the known diketopiperazine cyclo(S-Val-S-Phe) (3.9). In vitro biological studies revealed that cyclo(S-Val-S-Phe) is able to promote neurite outgrowth, even in the presence of physiological inhibitors. In vivo studies have shown that cyclo(S-VaI-S-Phe) is able promote sprouting in serotonergic and adrenergic axons. Synthesis of the other three diastereomers led to the discovery that cyclo(R-Val-R-Phe) is also an in vitro activator of axonal outgrowth. Inhibitors of the G2 checkpoint are able to increase the cytotoxicity of DNA damaging chemotherapeutics. Bioassay guided fractionation of an extract of the South American plant Duguetia odorata led to the isolation of the G2 checkpoint abrogator, oliveroline. This investigation also led to the isolation of the previously unreported alkaloid N-methylguatterine, and the known alkaloids dehydrodiscretine and pseudopalmatine. Chemical investigation of the marine sponge Myrmekioderma granulatum led to the isolation of the new compounds abolenone and myrmekioside C, as well as the known compounds curcudiol, curcuphenol, abolene and sesquiterpenoid. Biological studies of these compounds revealed that curcudiol is a ligand of the sex hormone-binding globulin. This protein is involved in transporting and regulating the concentration of steroids such as testosterone and estradiol. Many pathological conditions have a lower plasma concentration of these steroids. Ligands to SHBG can release steroids into the blood, so this protein is a potential drug target to treat conditions where a hormone insufficiency is present.
3

The total synthesis of (-)-pre-swinholide A

Smith, J. D. January 1994 (has links)
No description available.
4

Bioactive natural products from nature

Brastianos, Harry Charilaos 11 1900 (has links)
Bioassay guided fractionation of a crude extract of the marine sponge Neopetrosia exigua resulted in the first reported isolation of exiguamines A and B. These pyrroloquinone alkaloids have an unprecedented hexacyclic skeleton that has not been previously encountered in natural products. Biological studies have identified exiguamine A as a potent in vitro inhibitor of the enzyme indoleamine-2,3-dioxygenase (IDO). IDO is an enzyme expressed by tumor cells to evade the immune system. Inhibitors against this enzyme may allow the immune system to attack cancer cells, making this enzyme a potential drug target for anti-cancer agents. Investigation of the crude extract of a Bacillus sp. collected in Dominica led to the isolation of the known diketopiperazine cyclo(S-Val-S-Phe) (3.9). In vitro biological studies revealed that cyclo(S-Val-S-Phe) is able to promote neurite outgrowth, even in the presence of physiological inhibitors. In vivo studies have shown that cyclo(S-VaI-S-Phe) is able promote sprouting in serotonergic and adrenergic axons. Synthesis of the other three diastereomers led to the discovery that cyclo(R-Val-R-Phe) is also an in vitro activator of axonal outgrowth. Inhibitors of the G2 checkpoint are able to increase the cytotoxicity of DNA damaging chemotherapeutics. Bioassay guided fractionation of an extract of the South American plant Duguetia odorata led to the isolation of the G2 checkpoint abrogator, oliveroline. This investigation also led to the isolation of the previously unreported alkaloid N-methylguatterine, and the known alkaloids dehydrodiscretine and pseudopalmatine. Chemical investigation of the marine sponge Myrmekioderma granulatum led to the isolation of the new compounds abolenone and myrmekioside C, as well as the known compounds curcudiol, curcuphenol, abolene and sesquiterpenoid. Biological studies of these compounds revealed that curcudiol is a ligand of the sex hormone-binding globulin. This protein is involved in transporting and regulating the concentration of steroids such as testosterone and estradiol. Many pathological conditions have a lower plasma concentration of these steroids. Ligands to SHBG can release steroids into the blood, so this protein is a potential drug target to treat conditions where a hormone insufficiency is present. / Science, Faculty of / Chemistry, Department of / Graduate
5

Studies towards the synthesis of Popolohuanone E

Ross, Andrew R. January 1997 (has links)
No description available.
6

The total synthesis of neohalicholactone

Critcher, Douglas James January 1995 (has links)
No description available.
7

Chemical investigations of Natural Products from Australian Marine Sponge-Derived Fungi

Li, Hang, n/a January 2007 (has links)
This thesis described the chemical investigations of natural products from Australian marine sponge-derived fungi. Sponge samples were collected from the Great Barrier Reef, Queensland, Australia, by Queensland Museum. The thesis is divided into eight chapters and can be devided into two major parts. The first three chapters comprised the first part of the thesis: Chapter 1 outlined the research background, literature review of marine fungal secondary metabolites; Chapter 2 introduced fungal culture and storage background knowledge, and the list of isolated marine fungal strains. Chapter 3 introduced the background of the thrombin inhibition assay and assay results. The second part (Chapter 4 to 7) of this thesis is focused on chemical isolation and structure elucidation of secondary metabolites from isolated fungal strains, mostly active strains against thrombin. An unidentified fungal strain, FS-G315858 (T)-Y, isolated from the frozen sponge sample Dysidea sp.1400 produced five peptide compounds (chapter 4, 16-20). Compound 16 is a polypeptide which features the same relative configuration with a known compound unguisine A, and compounds 17-20 are diketopiperazines. Active fungal strains FS-G315695 (T)-Y and FDPS-61732-YB were isolated from different sponge samples. However, they were identified to be the identical fungal strain Eurotium rubrum; the chemical isolation of FS-G315695 (T)-Y from its mycelia EtOAc extract resulted in three compounds (chapter 5, 17-19). Compounds 18 and 19 were identified to be flavoglaucin and iso-dihydroauroglaucin. Compound 17 was identified to have the same relative configuration with a known compound neo-echinulin A. The chemical isolation of FDPS-61732-YB from its broth EtOAc extract resulted in several diketopiperazines (chapter 5, 27-29). Another active fungal strain FS-G315695 (T)-WY was identified as Aspergillus ochraceous, the chemical isolation of its mycelia EtOAc extract resulted in one benzodiazepine compound (chapter 6, 18), together with two fatty acids (chapter 6, 16-17). The structure of compound 18 was elucidated and identified to have same relative configuration with the known compound circumdatin E. Media comparison for active fungal strain FS-G315695 (T)-Y was conducted and this work resulted in producing several neo-echinulin analogues (chapter 7, 1-3). The isolation and structure elucidation of these compounds were reported in chapter 7.
8

Bioprospecção de proteínas da esponja marinha Aaptos sp. por análise proteômica / Protein bioprospecting of the marine sponge Aaptos sp. by proteomic analysis

Martins, Maria Gleiciane De Queiroz January 2015 (has links)
MARTINS, Maria Gleiciane De Queiroz. Bioprospecção de proteínas da esponja marinha Aaptos sp. por análise proteômica. 2015. 67 f. : Tese (doutorado) - Universidade Federal do Ceará, Centro de Ciências Agrárias, Departamento de Engenharia de Pesca, Fortaleza-CE, 2015 / Submitted by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-27T14:14:45Z No. of bitstreams: 1 2015_tese_mgqmartins.pdf: 1676608 bytes, checksum: 5949b16ede3a943dff4e0208ea167426 (MD5) / Approved for entry into archive by Nádja Goes (nmoraissoares@gmail.com) on 2016-07-27T14:15:02Z (GMT) No. of bitstreams: 1 2015_tese_mgqmartins.pdf: 1676608 bytes, checksum: 5949b16ede3a943dff4e0208ea167426 (MD5) / Made available in DSpace on 2016-07-27T14:15:02Z (GMT). No. of bitstreams: 1 2015_tese_mgqmartins.pdf: 1676608 bytes, checksum: 5949b16ede3a943dff4e0208ea167426 (MD5) Previous issue date: 2015 / Marine sponges are a rich reserve of natural substances, many of them of immense biotechnological interest. They comprise a promising group in providing bioactive compounds for humanity. Thus, research on new drugs from natural sources suggest that marine sponges have important bioactive compounds ponteciais: pharmacological, antimicrobial; antitumor; antiviral; anti-inflammatory; immunosuppressive; cardiovascular; neurosupressor; muscle relaxant and pollution biomarker. Analysis of expressed proteins is an important approach to determine the function of these molecules in a given organism. This study aimed to bioprospect proteins expressed by the marine sponge Aaptos sp. collected in Icarai de Amontada, Ceará, who may have biotechnological potential. For the realization of this approach were used as strategies the two-dimensional electrophoresis (2-DE) and bioinformatics. The 2-DE is a tool used to separate proteins from different organisms. Knowing the proteins expressed in the study sponge can be established Protein patterns characteristic of the species under study. Based on the above, this study used 2DE to investigate the expressed protein Aaptos sp. In order to make the extraction of total proteins was performed using 400 mg of the marine sponge Aaptos sp. For qualitative and quantitative analysis of proteins was used the method of Bradford and SDS-PAGE, respectively. From the total protein extract was determined the two-dimensional reference map for marine sponge in the study. The adjustment of images of two-dimensional gels, the protein spot detection and evaluation of data to determine apparent molecular weight (MW) and isoelectric point (pI) of the spots was made by the ImageMaster software 7. Expressed proteins were identified using the values of pI and MM spot against a UniProt protein database available on the ExPASy server. The average number of protein spots of replicas of the gels 2DE was 124. The highest abundance proteins was observed in 2DE gels in the pH range of 4 to 6.7 and with MM between 13 to 119.67 kilodalton (kDa). From the 2DE reference gel was identified 122 proteins of which 61, 46 and 15 belong to the Cnidaria taxon deuterostomia and Porifera, respectively. The proteins identified Porifera belong to functional category: ATP binding, structural component of the ribosome, catalytic activity, GTP binding, calcium ion binding and disulfide oxidoreductase activity. The functional category binding of ATP and GTP with more spots. Adicionadamente, was expressed proteins with important molecular functions already hued in the literature but not in Aaptos sp., thus indicating the importance of these marine sponges as a source of protein information that may be studied in the future for their potential use as biotechnological tools in several areas and can be used in studies to elucidate the metabolic pathways and the development of drugs against possible pathologies. / As esponjas marinhas constituem uma rica reserva de substâncias naturais, muitas delas de imenso interesse biotecnológico. Elas compreendem um grupo promissor no fornecimento de compostos bioativos para a humanidade. Desta forma, pesquisas de novas drogas de fontes naturais sugerem que as esponjas marinhas possuem importantes compostos bioativos com ponteciais: farmacológico, antimicrobiano; antitumoral; antiviral; antiinflamatório; imunossupresor; cardiovascular; neurosupressor; relaxante muscular bem como biomarcador de poluição. A análise de proteínas expressas é uma abordagem importante para determinar a função dessas moléculas em um determinado organismo. Esse trabalho teve como objetivo bioprospectar proteínas expressas pela esponja marinha Aaptos sp. coletada no Icaraí de Amontada, Ceará, que possam apresentar potencial biotecnológico. Para a realização dessa abordagem, foram utilizadas como estratégias a eletroforese bidimensional (2-DE) e a bioinformática. A 2-DE é uma ferramenta utilizada para separar proteínas de diversos organismos. Conhecendo-se as proteínas expressas na esponja estudada pode-se estabelecer padrões protéicos característicos da espécie em estudo. Com base no exposto, neste estudo foi utilizado 2DE para investigar as proteínas expressas de Aaptos sp. A fim de fazer a extração de proteínas totais foi realizada a partir de 400 mg da esponja marinha Aaptos sp. Para análise quantitativa e qualitativa das proteínas foi utilizado o método de Bradford e SDS-PAGE, respectivamente. A partir das proteínas totais extraídas foi determinado o mapa bidimensional de referência para a esponja marinha em estudo. O ajuste das imagens dos géis bidimensionais, a detecção de spots protéicos e a avaliação dos dados para determinação massa molecular aparente (MM) e ponto isoelétrico (pI) dos spots foi feito pelo programa ImageMaster 7. Proteínas expressas foram identificadas utilizando os valores de pI e MM do spot contra um banco de dados de proteínas UniProt disponível no servidor ExPASy. O número médio de spots protéicos das replicas dos géis 2DE foi de 124. A maior abundância de proteínas foi observada nos géis 2DE na faixa de pH de 4 a 6,7 e com MM entre 13 a 119,67 quilodalton (kDa). A partir do gel 2DE de referencia foi identificado 122 proteínas das quais 61, 46 e 15 pertencem aos táxon cnidária, deuterostomia e porífera, respectivamente. As proteínas identificadas de porífera pertencem a categoria funcional: ligante de ATP, componente estrutural do ribossomo, atividade catalítica, ligante de GTP, ligante de íon de cálcio e atividade dissulfeto oxidoredutase. Sendo a categoria funcional ligante de ATP e de GTP com maior número de spots. Adicionadamente, houve proteínas expressas com importantes funções moleculares já relada na literatura, porém não em Aaptos sp., assim indicando a importância destas esponjas marinhas como fonte de informação proteica que poderão ser estudadas no futuro quanto ao seu potencial uso como ferramentas biotecnológicas em diversas áreas, podendo ser empregadas em estudos que possam elucidar as vias metabólicas bem como o desenvolvimento de fármacos contra possíveis patologias.
9

BioprospecÃÃo de proteÃnas da esponja marinha Aaptos sp. por anÃlise proteÃmica / Protein bioprospecting of the marine sponge Aaptos sp. by proteomic analysis

Maria Gleiciane De Queiroz Martins 06 February 2015 (has links)
CoordenaÃÃo de AperfeiÃoamento de Pessoal de NÃvel Superior / As esponjas marinhas constituem uma rica reserva de substÃncias naturais, muitas delas de imenso interesse biotecnolÃgico. Elas compreendem um grupo promissor no fornecimento de compostos bioativos para a humanidade. Desta forma, pesquisas de novas drogas de fontes naturais sugerem que as esponjas marinhas possuem importantes compostos bioativos com ponteciais: farmacolÃgico, antimicrobiano; antitumoral; antiviral; antiinflamatÃrio; imunossupresor; cardiovascular; neurosupressor; relaxante muscular bem como biomarcador de poluiÃÃo. A anÃlise de proteÃnas expressas à uma abordagem importante para determinar a funÃÃo dessas molÃculas em um determinado organismo. Esse trabalho teve como objetivo bioprospectar proteÃnas expressas pela esponja marinha Aaptos sp. coletada no Icaraà de Amontada, CearÃ, que possam apresentar potencial biotecnolÃgico. Para a realizaÃÃo dessa abordagem, foram utilizadas como estratÃgias a eletroforese bidimensional (2-DE) e a bioinformÃtica. A 2-DE à uma ferramenta utilizada para separar proteÃnas de diversos organismos. Conhecendo-se as proteÃnas expressas na esponja estudada pode-se estabelecer padrÃes protÃicos caracterÃsticos da espÃcie em estudo. Com base no exposto, neste estudo foi utilizado 2DE para investigar as proteÃnas expressas de Aaptos sp. A fim de fazer a extraÃÃo de proteÃnas totais foi realizada a partir de 400 mg da esponja marinha Aaptos sp. Para anÃlise quantitativa e qualitativa das proteÃnas foi utilizado o mÃtodo de Bradford e SDS-PAGE, respectivamente. A partir das proteÃnas totais extraÃdas foi determinado o mapa bidimensional de referÃncia para a esponja marinha em estudo. O ajuste das imagens dos gÃis bidimensionais, a detecÃÃo de spots protÃicos e a avaliaÃÃo dos dados para determinaÃÃo massa molecular aparente (MM) e ponto isoelÃtrico (pI) dos spots foi feito pelo programa ImageMaster 7. ProteÃnas expressas foram identificadas utilizando os valores de pI e MM do spot contra um banco de dados de proteÃnas UniProt disponÃvel no servidor ExPASy. O nÃmero mÃdio de spots protÃicos das replicas dos gÃis 2DE foi de 124. A maior abundÃncia de proteÃnas foi observada nos gÃis 2DE na faixa de pH de 4 a 6,7 e com MM entre 13 a 119,67 quilodalton (kDa). A partir do gel 2DE de referencia foi identificado 122 proteÃnas das quais 61, 46 e 15 pertencem aos tÃxon cnidÃria, deuterostomia e porÃfera, respectivamente. As proteÃnas identificadas de porÃfera pertencem a categoria funcional: ligante de ATP, componente estrutural do ribossomo, atividade catalÃtica, ligante de GTP, ligante de Ãon de cÃlcio e atividade dissulfeto oxidoredutase. Sendo a categoria funcional ligante de ATP e de GTP com maior nÃmero de spots. Adicionadamente, houve proteÃnas expressas com importantes funÃÃes moleculares jà relada na literatura, porÃm nÃo em Aaptos sp., assim indicando a importÃncia destas esponjas marinhas como fonte de informaÃÃo proteica que poderÃo ser estudadas no futuro quanto ao seu potencial uso como ferramentas biotecnolÃgicas em diversas Ãreas, podendo ser empregadas em estudos que possam elucidar as vias metabÃlicas bem como o desenvolvimento de fÃrmacos contra possÃveis patologias. / Marine sponges are a rich reserve of natural substances, many of them of immense biotechnological interest. They comprise a promising group in providing bioactive compounds for humanity. Thus, research on new drugs from natural sources suggest that marine sponges have important bioactive compounds ponteciais: pharmacological, antimicrobial; antitumor; antiviral; anti-inflammatory; immunosuppressive; cardiovascular; neurosupressor; muscle relaxant and pollution biomarker. Analysis of expressed proteins is an important approach to determine the function of these molecules in a given organism. This study aimed to bioprospect proteins expressed by the marine sponge Aaptos sp. collected in Icarai de Amontada, CearÃ, who may have biotechnological potential. For the realization of this approach were used as strategies the two-dimensional electrophoresis (2-DE) and bioinformatics. The 2-DE is a tool used to separate proteins from different organisms. Knowing the proteins expressed in the study sponge can be established Protein patterns characteristic of the species under study. Based on the above, this study used 2DE to investigate the expressed protein Aaptos sp. In order to make the extraction of total proteins was performed using 400 mg of the marine sponge Aaptos sp. For qualitative and quantitative analysis of proteins was used the method of Bradford and SDS-PAGE, respectively. From the total protein extract was determined the two-dimensional reference map for marine sponge in the study. The adjustment of images of two-dimensional gels, the protein spot detection and evaluation of data to determine apparent molecular weight (MW) and isoelectric point (pI) of the spots was made by the ImageMaster software 7. Expressed proteins were identified using the values of pI and MM spot against a UniProt protein database available on the ExPASy server. The average number of protein spots of replicas of the gels 2DE was 124. The highest abundance proteins was observed in 2DE gels in the pH range of 4 to 6.7 and with MM between 13 to 119.67 kilodalton (kDa). From the 2DE reference gel was identified 122 proteins of which 61, 46 and 15 belong to the Cnidaria taxon deuterostomia and Porifera, respectively. The proteins identified Porifera belong to functional category: ATP binding, structural component of the ribosome, catalytic activity, GTP binding, calcium ion binding and disulfide oxidoreductase activity. The functional category binding of ATP and GTP with more spots. Adicionadamente, was expressed proteins with important molecular functions already hued in the literature but not in Aaptos sp., thus indicating the importance of these marine sponges as a source of protein information that may be studied in the future for their potential use as biotechnological tools in several areas and can be used in studies to elucidate the metabolic pathways and the development of drugs against possible pathologies.
10

De novo Transcriptome Analysis of the Marine Sponge Cinachyrella spp: A Potential Model Organism for Oil and Dispersant Ecotoxicology

Smith, Emily 01 May 2013 (has links)
In order to study the potential effects of an oil spill on coral reef organisms, the marine sponge, Cinachyrella spp. was investigated. In this study, Cinachyrella spp. was placed in a closed aquaculture system and exposed to sub-lethal water-accommodated fractions (WAFs) of Macondo crude oil and chemically-enhanced water accommodated fractions (CE-WAFs) of the dispersant, Corexit 9500, over a 24-hour time course, in order to model the BP Deepwater Horizon oil spill and oil spill sponge response. Illumina RNA sequencing and gene expression analysis utilizing hierarchical clustering, principal component analysis, and KEGG bioinformatic database generated 34,147 unique transcripts with differential expression of 483 transcripts across all samples related to metabolism, genetic, environmental, and cellular processes, and associations with pathways involved in human disease development and progression. These pathways highlight the induction of Rac1, a GTPase in the Ras superfamily responsible for cell proliferation, differentiation, and senescence and SOS, a set of specialized Ras-GTP activators. These Ras-regulated signaling proteins are thought to play a significant role in the development of human malignancies, specifically Rac1. The data reported here helps support the possible role of Cinachyrella spp. as an ecotoxicological model for oil and dispersant pollution as well as the identification of potential biomarkers of stress and environmental perturbation. These results have important implications in identifying stress response in coral reef associated communities, and will ultimately be useful in coral reef conservation, management, and oil spill mitigation activities.

Page generated in 0.0837 seconds