RESUMO
The major glycosphingolipid in pig vascular endothelium is the ceramide pentasaccharide Gal alpha(1 --> 3)Gal beta(1 --> 4)GlcNAc beta(1 --> 3)Gal beta(1 --> 4)Glc beta(1 --> 0)Cer (1), which binds specifically to human anti-Gal antibody and is involved in the hyperacute rejection response in xenotransplantation from pig to man. The synthesis of 1 and its methyl glycoside 2 is described.
Assuntos
Antígenos Heterófilos/biossíntese , Glicoesfingolipídeos/síntese química , Rejeição de Enxerto/imunologia , Oligossacarídeos/síntese química , Transplante Heterólogo/imunologia , Animais , Anticorpos Heterófilos/imunologia , Antígenos Heterófilos/efeitos adversos , Antígenos Heterófilos/química , Configuração de Carboidratos , Sequência de Carboidratos , Endotélio Vascular/química , Galactose/imunologia , Glicoesfingolipídeos/imunologia , Humanos , Dados de Sequência Molecular , Suínos , Transplante Heterólogo/efeitos adversosAssuntos
Anticorpos Heterófilos/sangue , Dissacarídeos/imunologia , Rejeição de Enxerto/prevenção & controle , Transplante de Coração/imunologia , Transplante Heterólogo/imunologia , Doença Aguda , Animais , Animais Geneticamente Modificados , Antígenos CD/genética , Antígenos CD/imunologia , Antígenos CD55/genética , Antígenos CD55/imunologia , Complemento C3/análise , Complemento C4/análise , Endotélio Vascular/imunologia , Rejeição de Enxerto/imunologia , Humanos , Imunoglobulina M/análise , Papio , SuínosRESUMO
An early step of the inflammatory response-the rolling of leukocytes on activated endothelial cells-is mediated by selectin/carbohydrate interactions. The tetrasaccharide sialyl Lewis(x) (sLe(x)) 1 is a ligand for E-, P-, and L-selectin and, therefore, serves as a lead structure to develop analogues which allow the control of acute and chronic inflammation. Here we describe the efficient synthesis (10 linear steps) of the potent sLe(x) mimetic 2. Compared to sLe(x), compound 2 showed a 30-fold improved affinity in a static, cell-free E-selectin-ligand binding assay (IC(50) = 36 microM). These data were confirmed by a marked inhibition in an in vitro cell-cell rolling assay which simulates in vivo conditions (IC(50) approximately 40 microM). The assays are predictive for the in vivo efficacy of test compounds as indicated by a marked inhibitory effect of 2 in a thioglycollate induced peritonitis model of acute inflammation in mice (ED(50) approximately 15 mg/kg).
Assuntos
Selectina E/metabolismo , Oligossacarídeos/síntese química , Doença Aguda , Animais , Sequência de Carboidratos , Ligantes , Camundongos , Mimetismo Molecular , Dados de Sequência Molecular , Oligossacarídeos/química , Oligossacarídeos/farmacologia , Peritonite/induzido quimicamente , Peritonite/tratamento farmacológico , Antígeno Sialil Lewis X , Relação Estrutura-Atividade , TioglicolatosRESUMO
The synthesis of the ethoxycarbonyloctanyl glycoside of the Lewis-Y (Ley) tetrasaccharide, a part of complex glycosphingolipids, was based on the trichloroacetimidate method for glycoside synthesis. The regioselective introduction of protective groups and the high yield of epimers of the azidonitration reaction applied to O-[2,3,4-tri-O-acetyl-6-O-[dimethyl-(2,3-dimethyl-2-butyl)silyl]-beta-D- galactopyranosyl]-(1-->4)-3-O-acetyl-1,5-anhydro-6-O-[dimet hyl-(2,3- dimethyl-2-butyl)silyl]-D-arabino-hex-1-enitol led to a lactosamine acceptor molecule. The double specific introduction of an alpha-L-fucosyl group in high yield gave a protected Ley-tetrasaccharide. After activation to give the alpha-trichloroacetimidate, specific beta-glycosylation with 8-ethoxycarbonyl octanol under SN 2 condition, followed by cleavage of all protective groups led to the tetrasaccharide, alpha-L-Fucp-(1-->2)-beta-D-galp-(1-->4)-[alpha-L-fucp-(1--> 3)]-beta-D- GlcpNAcO(CH2)8CO2Et in high yield.
Assuntos
Antígenos de Neoplasias/química , Antígenos do Grupo Sanguíneo de Lewis/química , Oligossacarídeos/síntese química , Configuração de Carboidratos , Sequência de Carboidratos , Carboidratos , Glicoesfingolipídeos/química , Indicadores e Reagentes , Espectroscopia de Ressonância Magnética , Dados de Sequência Molecular , Relação Estrutura-AtividadeRESUMO
The synthesis of the methyl alpha- and beta-N-dansyl-D-galactosaminides is described using methyl alpha,beta-2-azido-2-deoxy-D-galactopyranoside as starting material. This was reduced to the corresponding methyl alpha,beta-2-amino-2-deoxy-D-galactopyranoside and then treated with dansyl chloride to yield a mixture of methyl alpha,beta-N-dansyl-D-galactosaminides which was separated into individual anomeric forms by flash chromatography on silica gel. Methyl alpha-N-dansyl-D-galactosaminide was used as a fluorescent indicator ligand in continuous substitution titrations to determine the association constants of nonchromophoric carbohydrates with the N-acetyl-D-galactosamine specific lectin from Erythrina corallodendron.
Assuntos
Acetilgalactosamina/metabolismo , Compostos de Dansil/síntese química , Galactosamina/análogos & derivados , Lectinas/metabolismo , Galactosamina/síntese química , Sondas Moleculares , Estrutura Molecular , Ligação Proteica , Sensibilidade e Especificidade , Espectrometria de FluorescênciaRESUMO
Mucin-type O-glycopeptides containing the beta-D-Galp-(1----3)-D-GalpNAc disaccharide core unit, which is also the T-antigenic determinant, were synthesized from D-galactose, 2-azido-2-deoxy-D-galactose, 2-azido-2-deoxylactose, and L-serine precursors by applying the trichloroacetimidate method. Thus, beta-D-Galp-(1----3)-alpha-D-GalpNAc-(1----3)-Ser (1) and beta-D-Galp-(1----4)-beta-D-GlcpNAac-(1----6)-[beta-D-Galp-(1----3 )]-alpha-D-GalpNAc-(1----3)-Ser (2) were obtained. A protected precursor of 2 having free OH groups at C-4 and C-6 of the inner sugar unit is a valuable intermediate for the synthesis of further O-glycopeptides of this core-unit type.