The Total Synthesis of Zetekitoxin AB

 描述(申请人提供)：这项研究项目包括完全合成非常有效的胍毒，zetekitoxin AB(ZTX)。ZTX具有阻断电压门控钠通道(NAV)和皮摩尔活性的特殊能力。然而，与相关的胍类毒物相比，导致其活性增加的结构特征仍不清楚。ZTX的合成工作将基于以前合成的中间体，这些中间体是在赞助实验室合成相关的胍类毒素--GTX(GTX)时获得的。这条路线的重点是在Rh催化的氧化环化反应中访问ZTX的双胍基核。将相应地探索和开发合成方法学，以获得ZTX的大环内酰胺和N-羟基氨基甲酸酯的功能。ZTX的灵活合成将允许对ZTX类似物进行重点检查，从而深入了解与钠通道的具体相互作用。电生理分析将使用全细胞电压钳技术针对所有钠通道亚型(Nav1.1-9和Nax)进行，因为到目前为止，ZTX只针对三种异构体进行了测试。这将提供一种信息丰富的方法来揭示任何单个通道亚型的特异性。一种具有皮摩尔活性的特异性异构体抑制剂将是研究损伤神经元中特异性通道异构体分布的一种非常有价值的工具。蛋白质诱变将 也被用来探索与特定氨基酸残基的拟议相互作用，这些氨基酸残基被认为是小分子结合的关键。该项目的总体目标是完成ZTX的全合成，并增加对ZTX结合功效的NAV通道的了解。从这项研究中积累的知识可能会导致新的简化小分子，有望用于治疗炎症和神经性疼痛。

 DESCRIPTION (provided by applicant): This research project encompasses the total synthesis of the remarkably potent guanidinium poison, zetekitoxin AB (ZTX). ZTX has an exceptional ability to block volatage-gated sodium channels (NaV) with picomolar activity. However, the structural features responsible for its increased activity compared to related guanidinium poisons remains unknown. Synthetic efforts toward ZTX will be based on previously synthesized intermediates accessed in the sponsoring lab's synthesis of the related guanidinium toxin, gonyautoxin (GTX). The route is highlighted by a rhodium-catalyzed oxidative cyclization to access ZTX's bis-guanidinium core. Synthetic methodology will be explored and developed accordingly to access ZTX's macroclactam and N-hydroxycarbamate functionalities. A flexible synthesis of ZTX would allow a focused examination of ZTX analogues that could provide insight into specific interactions with sodium channels. Electrophysiology assays will be performed using whole-cell voltage-clamp techniques against all sodium channel isoforms (NaV1.1-9 and NaX), as ZTX has only been tested against three isoforms to date. This will provide an information rich approach to reveal specificity towards any individual channel isoform. A specific isoform inhibitor with picomolar activity would be an extremely valuable tool to study the distribution of specific channel isoforms in injured neurons. Protein mutagenesis will also be used to probe proposed interactions with specific amino acid residues hypothesized to be crucial for small molecule binding. This project's overall goal is to complete the total synthesis of ZTX and increase understanding of NaV channels with respect to ZTX's binding efficacy. The knowledge accrued from this study could lead to new simplified small molecules that hold promise for treating inflammation and neuropathic pain.