RESUMO
The ribose and phosphorus contents in Haemophilus influenzae type b (Hib) capsular polysaccharide (CPS) are two important chemical indexes for the development and quality control of Hib conjugate vaccine. A quantitative 1H- and 31P-NMR method using a single internal standard was developed for simultaneous determination of ribose and phosphorus contents in Hib CPS. Hexamethylphosphoramide (HMPA) was successfully utilized as an internal standard in quantitative 1H-NMR method for ribose content determination. The ribose and phosphorus contents were found to be affected by the concentration of polysaccharide solution. Thus, 15-20 mg·L-1 was the optimal concentration range of Hib CPS in D2O solution for determination of ribose and phosphorus contents by this method. The ribose and phosphorus contents obtained by the quantitative NMR were consistent with those obtained by traditional chemical methods. In conclusion, this quantitative 1H- and 31P-NMR method using a single internal standard shows good specificity, accuracy and precision, providing a valuable approach for the quality control of Hib glycoconjugate vaccines.
Assuntos
Vacinas Anti-Haemophilus , Haemophilus influenzae tipo b , Fósforo , Polissacarídeos Bacterianos , RiboseRESUMO
Bacterial surface glycans perform a diverse and important set of biological roles, and have been widely used in the treatment of bacterial infectious diseases. The majority of bacterial surface glycans are decorated with diverse rare functional groups, including amido, acetamidino, carboxamido and pyruvate groups. These functional groups are thought to be important constituents for the biological activities of glycans. Chemical synthesis of glycans bearing these functional groups or their variants is essential for the investigation of structure-activity relationships by a medicinal chemistry approach. To date, a broad choice of synthetic methods is available for targeting the different rare functional groups in bacterial surface glycans. This article reviews the structures of naturally occurring rare functional groups in bacterial surface glycans, and the chemical methods used for installation of these groups.
Assuntos
Infecções Bacterianas , Polissacarídeos , Humanos , Polissacarídeos/química , Relação Estrutura-AtividadeRESUMO
Most bacterial cell surface glycans are structurally unique, and have been considered as ideal target molecules for the developments of detection and diagnosis techniques, as well as vaccines. Chemical synthesis has been a promising approach to prepare well-defined oligosaccharides, facilitating the structure-activity relationship exploration and biomedical applications of bacterial glycans. L-Galactosaminuronic acid is a rare sugar that has been only found in cell surface glycans of gram-negative bacteria. Here, an orthogonally protected L-galactosaminuronic acid building block was designed and chemically synthesized. A synthetic strategy based on glycal addition and TEMPO/BAIB-mediated C6 oxidation served well for the transformation of commercial L-galactose to the corresponding L-galactosaminuronic acid. Notably, the C6 oxidation of the allyl glycoside was more efficient than that of the selenoglycoside. In addition, a balance between the formation of allyl glycoside and the recovery of selenoglycoside was essential to improve efficiency of the NIS/TfOH-catalyzed allylation. This synthetically useful L-galactosaminuronic acid building block will provide a basis for the syntheses of complex bacterial glycans.
Assuntos
Carboidratos , Polissacarídeos , Glicosídeos , Oligossacarídeos , Oxirredução , Polissacarídeos/químicaRESUMO
D-Glycero-D-mannno-heptose 1ß, 7-bisphosphate (HBPß) is an important intermediate for constructing the core structure of Gram-negative bacterial lipopolysaccharides and was reported as a pathogen-associated molecular pattern (PAMP) that regulates immune responses. HBPß with 3-O-amyl amine linker and its monophosphate derivative D-glycero-D-mannno-heptose 7-phosphate (HP) with 1α-amyl amine linker have been synthesized as candidates for immunity study of HBPß. The O3-amyl amine linker of heptose was installed by dibutyltin oxide-mediated regioselective alkylation under fine-tuned protecting condition. The stereoselective installation of 1ß-phosphate ester was achieved by NIS-mediated phosphorylation at low temperature. The strategy for installation of 3-O-amyl amine linker onto HBP derivative can be expanded to the syntheses of other conjugation-ready carbohydrates bearing anomeric phosphoester.