RESUMO
Compounds that alter endothelial cell growth are of interest in the development of angiogenesis modulators. A structurally diverse series of saccharide derivatives (glycosylamide conjugates) have been synthesized and evaluated for their effects on bovine aortic endothelial cell (BAEC) growth. Heparin-albumin (HA) reduced BAEC growth by 32% at 10 microg/mL and a number of the novel saccharide conjugates from the library were found to mimic the effect of HA as they also inhibit endothelial cell survival under identical conditions. Two thiophene conjugates, thioglucamide (24% inhibition at 35 microM) and a related glucuronide (26% inhibition at 33 microM) were the most potent inhibitors of BAEC growth, as determined using a methylthiazol tetrazolium (MTT) assay. The effects of thioglucamide and HA on absolute cell number were also studied using cell counting experiments; thioglucamide (47% after 24 h) was more potent than indicated by the MTT assay and initially reduced the BAEC number to a greater extent than HA (30% after 24 h); however, its actions were over more rapidly than were HA's as cell growth had returned to levels of the control after 72 h where HA still caused 25% inhibition. The binding of the monosaccharide conjugates to fibroblast growth factor (FGF-2) in competition with heparin-albumin by ELISA was investigated to establish the possible mechanism by which glycoconjugates could alter growth but there was no general correlation between reduction in viable cell population and binding to FGF-2. No glycoconjugate reduced the proliferation of mouse mammary epithelial cells, nor did any alter gross cell morphology, supporting a proposal that the reduction in BAEC survival by monosaccharide conjugates such as thioglucamide is a result of the inhibition of cell proliferation rather than being an induction of cytotoxicity. These studies indicate that cell biological studies to determine the mechanism of action of the simple monosaccharide conjugates may be worthwhile.
Assuntos
Células Endoteliais/efeitos dos fármacos , Glucose/química , Ácido Glucurônico/síntese química , Ácido Glucurônico/farmacologia , Oligossacarídeos/síntese química , Oligossacarídeos/farmacologia , Animais , Configuração de Carboidratos , Sequência de Carboidratos , Bovinos , Divisão Celular/efeitos dos fármacos , Linhagem Celular , Técnicas de Química Combinatória , Células Endoteliais/metabolismo , Fator 2 de Crescimento de Fibroblastos/farmacologia , Glucosídeos/farmacologia , Ácido Glucurônico/química , Heparina/farmacologia , Camundongos , Dados de Sequência Molecular , Estrutura Molecular , Oligossacarídeos/química , Albumina Sérica/farmacologia , Relação Estrutura-Atividade , Tiofenos/farmacologiaRESUMO
The reaction of silylated nucleophiles with 6,1-anhydroglucopyranuronic acid (glucuronic acid 6,1-lactones) catalysed by tin(IV) chloride provides 1,2-trans or 1,2-cis (deoxy)glycosides in a manner dependent on the donor structure. The alpha-glycoside was obtained for reactions of the donor with the 2-acyl group and 2-deoxydonors, whereas the 2-deoxy-2-iodo donor gave the beta-glycoside. Experimental evidence shows that when 1,2-cis-glycoside formation occurs, the anomerisation of initially formed 1,2-trans-glycosides catalysed by SnCl(4) is possible. The anomerisation of beta-D-glucopyranosiduronic acids was found to be faster, in some cases, than anomerisation of related beta-D-glucopyranosiduronic acid esters and beta-D-glucopyranoside derivatives and the rates are dependent on the structure of the aglycon. Moreover, the rates of anomerisation of beta-D-glucopyranuronic acid derivatives can be qualitatively correlated with rates of hydrolysis of beta-D-glucopyranosiduronic acids. Mechanistic possibilities for the reactions are considered.
Assuntos
Monossacarídeos/síntese química , Compostos de Estanho/química , Ácidos Urônicos/síntese química , Glicosilação , Estrutura Molecular , Monossacarídeos/química , Estereoisomerismo , Fatores de Tempo , Ácidos Urônicos/químicaRESUMO
The solution structure of glycosyl amides has been studied by using NMR. A strong preference is displayed by tertiary aromatic glycosyl amides for E-anti structures in contrast with secondary aromatic glycosyl amides where Z-anti structures predominate. The structural diversity displayed by these classes of molecules would seem to be important as the directional properties of the aromatic ring, or groups attached to the aromatic ring, would be determined by choosing to have either a secondary or tertiary amide at the anomeric center and could be considered when designing bioactive molecules with carbohydrate scaffolds. The structural analysis was also carried out for related divalent secondary and tertiary glycosyl amides and these compounds display preferences similar to that of the monovalent compounds. The constrained divalent compounds have potential for promoting formation of clusters that will have restricted structure and thus have potential for novel studies of mechanisms of action of multivalent ligands. Possible applications of such compounds would be as scaffolds for the design and synthesis of ligands that will facilitate protein-protein or other receptor-receptor interactions. The affinity of restricted divalent (or higher order) ligands, designed to bind to proteins that recognize carbohydrates which would facilitate clustering and concomitantly promote protein-protein interactions, may be significantly higher than monovalent counterparts or multivalent ligands without these properties. This may be useful as a new approach in the development of therapeutics based on carbohydrates.
Assuntos
Amino Açúcares/síntese química , Carboidratos/química , Desenho de Fármacos , Amidas/síntese química , Amidas/farmacologia , Amino Açúcares/farmacologia , Dimerização , Ligantes , Espectroscopia de Ressonância Magnética , Estrutura Molecular , Ligação Proteica/efeitos dos fármacosRESUMO
Inhibitors of FGF-2 binding to a heparin-albumin conjugate were identified by ELISA from a library of glucuronic acid derivatives. These compounds were also inhibitors of endothelial cell survival that is dependant on FGF-2 and heparin or heparan sulfate proteoglycans. The results indicate that these bioactive compounds may prove useful as lead structures for the further development of pharmaceutical agents capable of modulating biological activity of FGF-2.