Acinetobacter baumannii poses a serious threat to human health. Pathogenic bacterial lipopolysaccharides (LPSs) are potent immunogens for the development of antibacterial vaccines. To investigate the antigenic properties of A. baumannii LPS, five well-defined core oligosaccharide fragments from the LPS of A. baumannii SMAL and ATCC 19606 were synthesized. A divergent synthesis strategy based on orthogonally protected α-(2 → 5)-linked Kdo dimer 6 was developed. Selective exposure of different positions in this key precursor and then elongation of sugar chains via stereocontrolled formation of both 1,2-trans and 1,2-cis-2-aminoglycosidic linkages permitted the efficient synthesis of the targets. The synthetic route also highlights a 4-O and then 7-O glycosylation sequence for assembly of the novel 4,7-branched Kdo framework. Antigenicity assay using the glycan microarray technique disclosed that tetrasaccharide 3 featuring both 4,7-branch and α-(2 → 5)-Kdo-Kdo structural elements was a potential antigenic determinant.

中文翻译：

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鲍曼不动杆菌 SMAL 和 ATCC 19606 脂多糖核心寡糖的分歧合成及抗原性评价


鲍曼不动杆菌对人类健康构成严重威胁。致病性细菌脂多糖（LPS）是开发抗菌疫苗的有效免疫原。为了研究鲍曼不动杆菌LPS 的抗原特性，从鲍曼不动杆菌SMAL 和 ATCC 19606 的 LPS 中合成了五个明确的核心寡糖片段。开发了基于正交保护的 α-(2 → 5)-连接 Kdo 二聚体6的发散合成策略。选择性暴露该关键前体中的不同位置，然后通过立体控制形成 1,2-反式和 1,2-顺式-2-氨基糖苷键来延长糖链，从而可以有效合成靶标。该合成路线还强调了用于组装新型 4,7 分支 Kdo 框架的 4- O糖基化序列，然后是 7- O糖基化序列。使用聚糖微阵列技术的抗原性测定表明，具有4,7-分支和α-(2→5)-Kdo-Kdo结构元件的四糖3是潜在的抗原决定簇。