Made available in DSpace on 2014-06-11T19:35:08Z (GMT). No. of bitstreams: 0 Previous issue date: 2010-10-22Bitstream added on 2014-06-13T20:06:35Z : No. of bitstreams: 1 coqueiro_a_dr_araiq.pdf: 3444220 bytes, checksum: af4b8398d8cad29c3d2633b22662e0d8 (MD5) / Coordenação de Aperfeiçoamento de Pessoal de Nível Superior (CAPES) / Fundação de Amparo à Pesquisa do Estado de São Paulo (FAPESP) / Os testes biológicos realizados por pesquisadores colaboradores do NuBBE para as espécies selecionadas para este estudo Brosimum glaziovii e Kielmeyera variabilis indicaram K. variabilis como uma importante fonte de metabólitos especiais bioativos. O fracionamento bioguiado da fração AcOEt dos galhos de K. variabilis para isolamento de substâncias com potencial antimalárico foi realizado via teste químico com -hematina e in vitro com Plasmodium falciparum, levando a identificação das xantonas oxigenadas 3,6-diidroxi-1,4,8-trimetoxixantona, 3,5-diidroxi-4-metoxixantona, 3,4-diidroxi-6,8-dimetoxixantona, 3,4-diidroxi-2-metoxixantona, 5-hidroxi-1,3- dimetoxixantona, 2,3-dimetoxi-4-hidroxixantona, 3-hidroxi-2-metoxixantona e 2-hidroxi- 1-metoxi-xantona e o xantonolignóide kielcorina. Dentre as substâncias isoladas, o xatonolignóide kielcorina foi considerado ativo quando comparado ao padrão cloroquina. A avaliação do potencial tripanocida também foi realizada para as xantonas isoladas e dentre estas, a 3,4-diidroxi-2-metoxixantona foi a mais ativa, principalmente para a cepa resistente ao benzonidazol (cepa Bolívia). Na fração EHFB das folhas de B. glaziovii foi observado o potencial antichagásico desta espécie. Os resultados observados para os ensaios antioxidantes levaram ao isolamento dos flavonóides quercitrina, podocarpusflavona A e da mistura de quercetina-3-Oglicosídeo e quercetina-3-O-galactosídeo, evidenciando a importância dos grupos catecólicos na potencialização da ação antioxidante. O estudo bioguiado pela atividade antimicrobiana com seis cepas de Staphylococcus aureus resistentes à meticilina culminou no isolamento de um derivado prenilado do floroglucinol (HGK-1) o qual demonstrou ser responsável pela potente atividade demonstrada pela fração hexânica dos galhos de K. variabilis. As xantonas isoladas tiveram seu potencial antimicrobiano... / Several biological activities have been carried out by NuBBE’s collaborators aiming the identification of active extracts from plant species, and Brosimum glaziovii and Kielmeyera variables showed to be important sources of bioactive secondary metabolites. Bio-guided fractionation of the EtOAc bioactive fraction of the branches of K. variabilis by using of the chemical test -hematin, and in vitro by using of Plasmodium falciparum, led to the isolation and identification of oxygenated xanthones 3,6-dihydroxy-1,4,8-trimethoxyxanthone, 3,5-dihydroxy-4-methoxyxanthone, 3,4- dihydroxy-6,8-dimethoxyxanthone, 3,4-dihydroxy-2-methoxyxanthone, 1,3-dimethoxy- 5-hydroxyxanthone, 2,3-dimethoxy-4-hydroxyxantona, 3-hydroxy-2-methoxyxanthone and 2-hydroxy-1-methoxyxanthone and xantonolignoid kielcorin. Among the compounds isolated, the xatonolignoid keilcorine indicated activity when compared to the standard chloroquine. The assessment of potential trypanocidal was also a part of this work and among the isolated xanthones, 3,4-dihydroxy-2-methoxyxanthone showed to be the most active, especially against the resistant strain to benzonidazole (Bolivia strain). In hexane fraction of leaves from B. glaziovii was noted antichagasic potencial for this specie. The antioxidant test used in this study led to the isolation of several flavonoids with antioxidant activity: quercitrin, podocarpusflavone A and the mixture of quercetin-3-O-glucoside and quercetin-3-O-galactoside, showing the importance of catechol group for the potentiating of antioxidant activity. The bio-guided antimicrobial activity using six strains of methicillin-resistant Staphylococcus aureus resulted in the isolation of the prenylated phloroglucinol derivative (HGK-1), which proved to be responsible for the potent activity exhibited by the hexane extract of the branches of K. variabilis. The xanthones isolated were evaluated... (Complete abstract click electronic access below)

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A new leuco-anthocyanidin, (+)-7,4'dihydroxyflavan- 3:4-diol has been isolated from the heartwood of Guibourtia coleosperma. The heartwood extractives were fractionated by enrichment procedures involving fractional precipitation and Craig partitioning, to give a high RF (subscript) low molecular weight fraction containing the above leuco -anthocyanidin. This was further fractionated by "preparative" paper chromatography . The leuco-anthocyanidin was amorphous and present in low proportion (0.004%) in the wood. On boiling with alcoholic hydrochloric acid the compound gave an anthocyanidin which was identified as 3,7,4'-trihydroxyflavylium chloride. The degradation products formed by alkali fusion, on a micro-scale, were resorcinol and ♭-resorcylic acid, and also p (underscore)-hydroxybenzoic acid. This indicated resorcinol and phenol A and B nuclei respectively. The formation of amorphous dimethyl ether and tetra-acetoxy derivatives indicated two phenolic and two alcoholic hydroxyl groups. The above indicates that the compound was 7,4'-dihydroxyflavan- 3:4- diol and a molecular weight estimation showed it to be monomeric. Comparison of the infrared absorption spectra of the natural dimethyl ether with synthetic (±) dimethoxyflavan- 3:4-diol, to which a tentative 2:3- trans- 3:4-cis conformation had been assigned (Phatak and Kulkarni 94), showed close identity. Crystalline (±)-7, 4 '-dihydroxyflavan- 3:4 - diol was synthesised by catalytic hydrogenation over platinum oxide of the corresponoing (±) -7,4'-dihydroxyflavanonol. The flavanonol was synthesised by sodium hyposulphite reduction of the 7,4 ' -dihydroxyflavonol. The infrared absorption spectra of the natural and synthetic diols were similar but not identical. Chromatographic evidence showed the apparent identity of the synthetic and natural flavan- 3:4- diols, and two possible configurations were assigned for the natural flavan-3:4-diol. The new leuco-anthocyanidin was observed to form an O(underscore)-ethyl ether derivative on manipulation in ethanol. A monomeric leuco- fisetinidin from the heartwood was identified, by two dimensional paper chromatography, as (+) - mollisacacidin. The condensed tannins found also in the heartwood of G.(underscore)- coleosperma appear to be polymeric forms of leuco - fisetinidin and leuco - guibourtinidin. These polymeric tannins form a large proportion of the heartwood extractives and furnish high yields of fisetinidin and guibourtinidin chlorides on boiling with alcoholic hydrochloric acid. Examination of some other members of the Guibourtia spp . by paper chromatography showed that only G (underscore). coleosperma contained the new leuco - anthocyanidin as well as a leuco - fisetinidin. G. (underscore) tessmannii and G. (underscore) demeusii heartwoods contained only leuco-fisetinidin and the related polymers and a close chemical relationship to G.(underscore) coleosperma is thus apparent. G.(underscore) arnoldiana on the other hand is not chemically interrelated with the above members since it appeared to contain only leuco - cyanidin. (±) - 7,4 ' -Dihydroxyflavan- 4-ol was synthesised by hydrogenation of the corresponding flavanone over platinum oxide. Observations were made regarding its reddenig and ease of condensation.

No description available.

An extensive range of oxygen and sulphur substituted benzodiazepine analogues has been synthesised via Baeyer-Villiger and Schmidt reactions of specially prepared flavanone and N-acetyl-4-quinolone precursors. Alternative, cyclisation routes have also been used to prepare some of these compounds. Ring-opening reactions of 1,5-benzodioxepinones have been investigated and a detailed kinetic-mechanistic study of the Baeyer-Villiger reaction of flavanones has been carried out using 1 H NMR spectroscopy to explain the observed regiochemistry of oxygen insertion. The electron-impact mass spectrometric fragmentation patterns of series of 4-aryl-l ,5-benzoxathiepinones, 3-aryl-4, I-benzoxathiepinones and 3-aryl-4,1-benzoxathiepines have been studied using a combination of low-resolution, highresolution and metastable-peak analyses. The 170 NMR spectroscopic properties of various oxygenated analogues have also been studied. The binding affinities of selected benzodiazepine analogues for rat brain benzodiazepine receptors have been evaluated using a radioreceptor assay technique; at certain concentrations, some of test compounds exhibited remarkable potentiation of diazepam binding, others the ability to displace diazepam from benzodiazepine receptors. A conformational analysis of the 7-membered ring systems has been undertaken, using lH NMR spectroscopic, computer modelling and x-ray crystallographic techniques, and certain conformational preferences have been identified.

Previous studies [Martini, 1998] on the leaves of Combretum erythrophyllum (Combretaceae) confirmed the antimicrobial activity but the compounds responsible for the activity could not be identified due to insufficient material. The main aim of this study was therefore to isolate and identify the antimicrobial compounds from Combretum erythrophyllum leaf material. Trees around the Pretoria region were tested for variation in activity and a small difference in bioactivity between plants was noted. Leaf extracts were also tested for free radical scavenging activity exhibiting good antioxidant activity and possible anti-inflammatory activity. Toxicity tests using human lymphocytes showed that compounds isolated were not toxic to these human cells.For preliminary testing four standard organisms were used to compare the activity of antimicrobial components, namely Staphylococcus aureus, Enterococcus faecalis, Escherichia coli and Pseudomonas aeruginosa. These are isolates recommended by the National Committee for Clinical Laboratory Standards. The pure compounds isolated were tested using a wider spectrum of bacteria and fungi.Acetone as solvent extracted 14 antibacterial inhibitors in previous studies and was hence used for the crude extraction. The extracts were complex and group separation by solvent/solvent extraction yielded six fractions. The hexane and chloroform fractions were selected for further study. The hexane fraction contained mainly non-polar compounds and the chloroform fraction both non-polar and polar compounds. Both these fractions showed activity against S. aureus.Methods used for compound isolation were mainly column chromatography, preparative TLC and HPLC using solvents with different polarities and selectivity. Column chromatography produced the best results, yielding a number of pure compounds. Although PTLC was not as effective, seven highly active compounds were isolated from the hexane fraction but were too impure and in insufficient quantities for structure elucidation.NMR was the method used for identification of isolated compounds and confirmed by MS. The hexane fraction yielded primarily waxes and fatty acids. Although these compounds are known to exhibit good antimicrobial activity, they have not been used in medicinal research due to their poor pharmacokinetic properties and as a result further research with this fraction was abandoned. Previous work with the chloroform fraction produced triterpenoids but these were in insufficient quantity for identification. This study yielded seven antibacterial flavonoids from the same fraction, possibly due to different extraction techniques. Three of these compounds were flavones, i.e. apigenin, genkwanin and 5-hydroxy-7,4'-dimethoxyflavone and four flavonols were identified i.e. kaempferol, rhamnocitrin, rhamnazin and quercetin-5,3'-dimethylether. Although all these compounds are fairly common flavonoids they are all reported for the first time in Combretum erythrophyllum, and in some cases in the family Combretaceae.Bioassays showed selective antibacterial activity between different microorganisms. In some cases MIC values ranged in the order of 25-100 mg/ml with the overall best activity against Vibrio cholerae. For some of these compounds this is the first report of antibacterial activity. / Dissertation (PhD(Pharmacology))--University of Pretoria, 2003. / Pharmacology / unrestricted

No description available.

No / Two new prenylated flavanones, 2S-3¿-(2-hydroxy-3-methylbut-3-enyl)licoflavone-4¿-methyl ether (3) and 2S-3¿-(2- hydroxy-3-methylbut-3-enyl)abyssinone II (4), and four known flavanones (1, 2, 5, 6) were isolated from the stem bark of Erythrina addisoniae. The structures were elucidated on the basis of their spectroscopic and physicochemical data. None of the compounds showed antioxidative properties. 4¿-Methylabyssinone V (1) and abyssinoflavanone VII (6) showed moderate cytotoxic activity (IC50 ) 5 and 3.5 ¿mol/L, respectively), but apoptosis (caspase-3/7-activation, nuclear fragmentation) was selectively induced by abyssinoflavanone VII (6).

Breast cancer is the most common cancer among females and it is the leading cause of death in mid-age women. Epidemiological studies indicate that Asian women have a lower incidence of breast cancer compared with their counterparts in the West, which soy consumption has been suggested as a contributory factor. Soy and soy-based food contain a rich amount of phytoestrogens, which are suggested to be protective against cancer. Cyclooxygenase (COX) is the rate-limiting enzyme for the conversion of arachidonic acid to prostaglandins. Recent studies have revealed that up-regulation of cyclooxygenase-2 (COX-2), an isoform of COX, plays an important role in tumorigenesis and metastasis. COX-2 may facilitate carcinogenesis in a number of means, may include altering cell proliferation and apoptosis, enhancing angiogenesis and suppressing immune surveillance. Clinical examinations of breast cancer specimens indicated that COX-2 is overexpressed. In the present study, we investigated the effect of flavonoids on COX-2 expression in human breast cells. / Our results showed that daidzein and its metabolite eqoul, genistein, butein, isoliquiritigenin (ILN) and apigenin could inhibit phorbol 12-myristate 13-acetate (PMA)-induced COX-2 expression in breast cells MCF-7 and MCF-10A. The inhibitory effects were in concentration-dependent manners. Real-time PCR and western blot analysis showed that the flavonoids suppressed the induced mRNA and protein expression. Suppression could be observed in concentration as low as 0.1 muM. Luciferase reporter assay indicated that the inhibition was at the gene transactivation level. Further investigation using truncated hCOX-2 promoter plasmids revealed that the AP-1 site (-67/-61) and cyclic AMP response element (CRE) site (-59/-53) on hCOX-2 promoter were responsible for the suppression. Electrophoretic mobility shift assay results further confirmed that the flavonoids acted through inhibiting AP-1/CREB DNA binding to suppress the expression. / To examine the possible upstream signal transduction pathways involved, inhibitors of protein kinase A (PKA), protein kinase (PKC) and mitogen activated protein kinase (MAPK) were employed. Reporter gene assay revealed a possible involvement of ERK1/2 MAP kinase in AP-1 and/or CRE activation of hCOX-2 promoter. Taken together, these results suggested that the phytochemicals down-regulated PMA-induced COX-2 expression by counteracting AP-1 and CRE sites via the modulation of MAPK pathway. The findings might have significant implications in the chemopreventive and chemotherapeutic applications of flavonoids in breast cancer. / Lau, Tak Yi. / "December 2007." / Adviser: Lai Kwok Leung. / Source: Dissertation Abstracts International, Volume: 69-08, Section: B, page: 4734. / Thesis (Ph.D.)--Chinese University of Hong Kong, 2007. / Includes bibliographical references (p. 142-164). / Electronic reproduction. Hong Kong : Chinese University of Hong Kong, [2012] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Electronic reproduction. [Ann Arbor, MI] : ProQuest Information and Learning, [200-] System requirements: Adobe Acrobat Reader. Available via World Wide Web. / Abstracts in English and Chinese. / School code: 1307.

Poon, Ching Ho. / "October 2010." / Thesis (M.Phil.)--Chinese University of Hong Kong, 2011. / Includes bibliographical references (leaves 95-102). / Abstracts in English and Chinese. / ACKNOWLEDGEMENTS --- p.3 / TABLE OF CONTENTS --- p.4 / ABSTRACT --- p.6 / 摘要 --- p.8 / ABBREVIATIONS --- p.10 / LIST OF FIGURES --- p.11 / Chapter CHAPTER 1 --- GENERAL INTRODUCTION --- p.14 / Chapter CHAPTER 2 --- MATERIALS AND METHODS --- p.26 / Chemicals and materials --- p.26 / Mammalian cell culture --- p.27 / Reporter gene assay --- p.28 / Semi-quantitative real-time PCR --- p.30 / RNA degradation assay --- p.31 / Western Blotting --- p.32 / Electrophoretic mobility shift assay (EMSA) --- p.34 / EROD assay in intact cells --- p.35 / Statistical Analysis --- p.35 / Chapter CHAPTER 3 --- Two citrus bioflavonoids suppress DMBA-induced CYP1 gene expression and activity via antagonizing AhR transactivation activity --- p.36 / Chapter CHAPTER 4 --- Modulation of AhR-mediated CYP1 enzymes transcription by licorice flavonoids isoliquiritigenin --- p.60 / Chapter CHAPTER 5 --- Protein kinase signaling pathways are not involved in the modulation of AhR transactivation activity by flavonoids --- p.81 / Chapter CHAPTER 6 --- SUMMARY --- p.94 / BIBLIOGRAPHY --- p.97