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1.
Phys Chem Chem Phys ; 17(17): 11609-14, 2015 May 07.
Artigo em Inglês | MEDLINE | ID: mdl-25866853

RESUMO

The recently reported electro-catalytic reaction mechanism for the oxidation of cellulose is proposed to work also for the electro-oxidation of other polysaccharides (e.g. hemicelluloses). In this report, the electrochemical reactivity of some hemicelluloses (xylan, arabinoxylan, glucomannan, xyloglucan, and glucuronoxylan) in 1.3 M NaOH solution is described. The electrochemical property of each of the studied hemicelluloses at the Au electrode surface was characterized by cyclic voltammetry. Xylan, xyloglucan and glucuronoxylan were found to be electrochemically active. Electrochemical properties of xylan were further studied by electrochemical impedance spectroscopy. The electrochemical reaction products of xylan, obtained by extensive electrolysis of the xylan solution by cyclic voltammetry, were characterized by FTIR spectroscopy, (13)C-NMR spectroscopy, SEM and TEM. The structural studies suggest that the oxidized xylan is a functional material where some of the OH-groups have been oxidized to carboxyl groups making that part of the oxidation product soluble in water under ambient conditions (23 °C, pH 7). The other part remains insoluble in water and contains Au nanoparticles. This work indicates that other polysaccharides than cellulose can also be electrochemically oxidized.


Assuntos
Técnicas Eletroquímicas , Ouro/química , Polissacarídeos/química , Catálise , Eletrodos , Oxirredução , Tamanho da Partícula , Propriedades de Superfície
2.
Clin Vaccine Immunol ; 19(11): 1889-93, 2012 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-22993407

RESUMO

Immunostimulatory properties of synthetic structures mimicking the ß-(1→2)-linked mannans of Candida albicans were evaluated in vitro. Contrary to earlier observations, tumor necrosis factor (TNF) production was not detected after stimulation with mannotetraose in mouse macrophages. Divalent disaccharide 1,4-bis(α-D-mannopyranosyloxy)butane induced TNF and some molecules induced low levels of gamma interferon (IFN-γ) in human peripheral blood mononuclear cells (PBMC).


Assuntos
Candida albicans/química , Candida albicans/imunologia , Mananas/síntese química , Mananas/imunologia , Animais , Células Cultivadas , Humanos , Interferon gama/metabolismo , Leucócitos Mononucleares/imunologia , Macrófagos/imunologia , Camundongos , Camundongos Endogâmicos BALB C , Fator de Necrose Tumoral alfa/metabolismo
3.
Carbohydr Res ; 356: 295-8, 2012 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-22520504

RESUMO

Many different glycoconjugates, including saponins (e.g., hellebrin) and anthracyclines (e.g., doxorubicin), are known to display cytotoxic activities. In recent work, we have developed synthetic protocols for the synthesis of various glycoconjugates, focusing on glycosylation methods for different classes of biomolecules. Simultaneously a number of saponins and anthracyclines have been generated. In this note, the cytotoxic activities of these synthesized compounds are briefly addressed.


Assuntos
Antraciclinas/farmacologia , Antibióticos Antineoplásicos/farmacologia , Doxorrubicina/farmacologia , Glicoconjugados/farmacologia , Saponinas/farmacologia , Esteroides/farmacologia , Antraciclinas/síntese química , Antibióticos Antineoplásicos/síntese química , Linhagem Celular Tumoral , Proliferação de Células , Sobrevivência Celular , Doxorrubicina/síntese química , Feminino , Glicoconjugados/síntese química , Humanos , Concentração Inibidora 50 , Saponinas/síntese química , Esteroides/síntese química , Relação Estrutura-Atividade
4.
Steroids ; 77(1-2): 110-7, 2012 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-22085429

RESUMO

Polyhydroxylated steroids, such as brassinosteroids, phytoecdysteroids and steroid saponins, are structurally attractive compounds possessing a number of interesting biological properties. Accordingly, development of synthetic procedures to build steroid based structures mimicking the naturally occurring hydrophilic steroids is of topical interest. In the present work, a D-secoestrone derivative was modified further by Barbier-allylation - ring-closing metathesis - dihydroxylation sequence with the aim to prepare steroid based structures with limited hydrophilicity. A straightforward synthesis route was developed with the isolated yield for each step ranging from good to excellent. All compounds prepared were fully characterized by NMR spectroscopic techniques and completely assigned (1)H and (13)C spectra are reported herein. Finally, the effects of the synthesized amphiphilic steroid derivatives on the proliferation of cancer cells are reported and discussed.


Assuntos
Antineoplásicos/síntese química , Estradiol/análogos & derivados , Estradiol/síntese química , Tensoativos/síntese química , Antineoplásicos/farmacologia , Brassinosteroides/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Sobrevivência Celular/efeitos dos fármacos , Ensaios de Seleção de Medicamentos Antitumorais , Ecdisteroides/química , Estradiol/farmacologia , Humanos , Interações Hidrofóbicas e Hidrofílicas , Hidroxilação , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Saponinas/química , Tensoativos/farmacologia
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