V. Cholerae O100 O-Antigen Synthesis for Absolute Configuration
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Solution Overview
Problem
The synthesis of V. cholerae serotype O100 O-antigen trisaccharide repeating units is challenging due to 1,2-cis-α-glycosidic linkages and 1-2-trans-β-D-quinovosidic linkages, and the absolute configurations of dHh modifying groups are unclear, hindering the development of effective glycoconjugate vaccines.
Innovation Solution
A chemical synthesis method using three monosaccharide building blocks and five carboxylic acid derivatives through orthogonal protection, selective assembly, and amide coupling to synthesize four potential trisaccharide isomers, followed by NMR analysis to determine absolute configurations and immunological effects using a glycan microarray.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If conventional synthesis methods are used to construct O-antigen trisaccharide repeating units, then the synthesis process becomes extremely challenging and incomplete, but the structural complexity with 1,2-cis-α-glycosidic linkages and 1-2-trans-β-D-quinovosidic linkages cannot be avoided
Solution Approach 1:
The patent divides the complex trisaccharide synthesis into modular disaccharide building blocks (e.g., FucpNAc-Fucp4N disaccharide) that can be independently synthesized and then assembled. This segmentation allows each module to be optimized separately, making the overall complex structure achievable through systematic assembly rather than attempting to construct the entire trisaccharide in one complex process.
Solution Approach 2:
The patent employs preliminary protection of hydroxyl groups and pre-synthesis of disaccharide units with defined stereochemistry before final assembly. By preparing building blocks with predetermined configurations and protecting groups in advance, the actual coupling reactions can proceed more efficiently with fewer side reactions, addressing the complexity of forming multiple stereospecific glycosidic linkages.
2Measurement precision
If four potential trisaccharide isomers are synthesized to determine absolute configurations, then the immunological effects can be studied, but the synthesis time and resource requirements increase significantly
Solution Approach 1:
The patent focuses synthesis efforts on the specific dHh modifying group region where absolute configuration is uncertain, rather than synthesizing completely different trisaccharide structures. By maintaining consistency in other regions and only varying the dHh configuration, the patent minimizes redundant synthesis while still obtaining all necessary stereoisomers for configuration determination.
Solution Approach 2:
The patent uses NMR spectroscopy to compare the synthesized trisaccharide structures with natural O-antigen standards and each other to determine absolute configurations. This analytical copying/comparison approach allows determination of stereochemistry without requiring extensive additional synthesis or biological testing for each isomer.
3Reliability
If chemically synthesized oligosaccharides are used for vaccine development, then the immunogenicity can be enhanced, but the structural homogeneity and purity requirements become more stringent
Solution Approach 1:
The patent systematically varies protecting group parameters (e.g., using different silyl groups like TBS, TBDPS, TES) and glycosylation conditions to optimize the synthesis of each disaccharide building block. By carefully controlling reaction parameters such as temperature, catalysts, and solvent conditions, the patent achieves high stereoselectivity and minimizes formation of unwanted isomers, ensuring structural homogeneity in the final trisaccharide products.
Solution Approach 2:
The patent uses orthogonal protecting groups as temporary intermediaries that allow selective manipulation of specific hydroxyl groups during synthesis. These protecting groups (e.g., acetates, benzoyl, silyl ethers) act as mediators that enable stepwise construction of the trisaccharide with controlled stereochemistry, ensuring that only the desired isomers are formed while maintaining pathways for later deprotection to yield homogeneous final products.
Data Source
AI summary
The disclosure discloses a chemical synthesis method and an application of V. cholerae serotype O100 O-antigen oligosaccharides, belonging to the field of chemical technologies. The disclosure uses three monosaccharide building blocks and five carboxylic acid derivatives to synthesize five oligosaccharide fragments of V. cholerae serotype O100 O-antigen under the action of the solvent effect, temperature effect, neighboring group participation effect, etc., through orthogonal protection, selective assembly and amide coupling. The absolute configurations and immunological effects of 3,5-dihydroxyhexanoyl in the O-antigen trisaccharide are illustrated by the synthesized oligosaccharide fragments in combination with the NMR analysis and glycan microarray technology, thereby providing a theoretical basis for further structure-activity study and minimal antigenic epitope screening. The disclosure has excellent application prospects in the aspects of development of V. cholerae synthetic glycoconjugate vaccines and new drugs, etc.