HNK-1抗原相关寡糖的合成及构效关系研究

The human natural killer-1 (HNK-1) glyco-epitope is an important carbohydrate component of glycoproteins and glycolipids involved in cell-cell and cell-substrate interactions, cell migration and neurite outgrowth. Moreover, it was found that the expression of HNK-1 epitopes is positively correlated with fatal tumor disease and autoimmune-based peripheral neuropathies. To investigate these processes, it is necessary to have access to homogenous and structurally defined HNK-1 epitope related oligosaccharides and derivatives. This proposal aims to develop a practical method for the synthesis of these important molecules and study the molecular recognition of the HNK-1 oligosaccharides and derivatives. The proposal has two specific aims. Specific Aim 1 is to develop a general strategy for the synthesis of natural HNK-1 oligosaccharides and HNK-1 derivatives. This research plans to use the 2-naphthylmethyl (2-NAP), benzoyl (Bz), 2-tert-butyldimethylsilyl (TBS) and benzyl (Bn) group as orthogonal protecting group in the synthesis. In this regard, these electron-donating protecting groups will arm the glucuronic acid donor; and the final deprotection could be achieved selectively to access the sulfonation. Meanwhile, 2-nitroglycal will be used to prepare 2-nitrothiolactoside as the key building block, constituting the lactosamine component in these oligosaccharides. And the strategy of preactivation-based one-pot oligosaccharide assembly will be applied to construct these oligosaccharides with 2-toluenethiol as leaving groups. Specific Aim 2 is to study the structure-activity relationships of the HNK-1 oligosaccharides with their different receptors.

人类自然杀伤标志物抗原（HNK-1）是一类广泛存在于人类自然杀伤细胞和诸多粘附因子中的寡糖抗原结构，与细胞识别、粘附、迁移以及神经元的分化、生长等过程紧密相关。此外，HNK-1寡糖还影响恶性肿瘤及自身免疫性神经疾病的发生和发展。为了更好地研究HNK-1寡糖结构在生理、病理过程中的作用，本项目拟发展一条通用而又高效快速的合成策略来组装HNK-1系列相关寡糖：（1）通过理性设计获得正交保护的葡萄糖醛酸供体，使其既能够保证糖基供体的反应活性，又可以在寡糖骨架组装完成后实现选择性地脱保护，以便后期在特定羟基位点进行硫酸化操作。（2）发展以硝基糖烯为中间体的新方法来制备HNK-1的重要结构单元—乳糖胺模块。（3）筛选和优化活化体系，以基于“预活化”的一釜合成策略实现HNK-1系列寡糖及其衍生物的高效合成，并研究其与受体相互作用的构效关系。

人类自然杀伤标志物-1（human nature killer-1, HNK-1）糖抗原表位（又称为 CD 57 或者 Leu-7 抗原）以糖蛋白和糖脂的形式广泛存在于动物体内，能够调节神经系统的生长和发育、受损神经的修复，并且影响神经细胞的可塑性。此外，HNK-1相关寡糖也有着重要的病理学意义，其异常表达是一些恶性肿瘤（如神经胶质瘤、黑色素瘤等）发生和转移的重要指标。本项目的研究内容主要集中在发展高效的寡糖合成策略，实现HNK-1系列相关寡糖及其衍生物的大量合成。在本项目研究中，我们针对关键中间体半乳糖基模块发展了区域选择性的苯甲酰化方法，能够一釜获得3位羟基裸露的半乳糖基模块，并分别与葡萄糖基模块、氨基葡萄糖模块等进行糖苷化偶联，实现了HNK-1糖链的延伸。为了进一步构建带有HNK-1糖抗原的糖缀合物，又继续发展了三种甘露糖核心结构的高效制备方法。本项目的完成为HNK-1寡糖及其缀合物的高效制备提供了高效可靠的途径，本项目发展的高区域选择性的半乳糖基模块在多种天然产物的合成中也有广泛的应用。项目相关研究成果发表研究性论文1篇（第一标注），申请专利1项，培养毕业硕士研究生2名，联合培养硕士研究生3名。参加多次国内、国际学术会议并进行口头报告。