Scarce natural products that possess unique biological activities have been ideal drug leads for decades. However, their identification and structural determinations are problematic owing to sample amount limitation. Inspired by an extremely rare natural product yaku’amide B (10), highly sensitive labeling reagents that would be powerful tools for scarce natural product chemistry were designed and synthesized in this study. By fusion with the key structural motif for the structural revision of 10, the detection sensitivities of amino acid labeling reagents were drastically enhanced in LC–MS analysis. These advanced labeling reagents enabled the detection of infinitesimal amounts of amino acids and peptide hydrolysates. This sensitivity-enhancement design concept was also applicable to reagents for labeling saccharides and reactivity-guided isolation of electrophilic natural products. Details of these reagents, including their practical preparations and extended applications, are also provided.

中文翻译：

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稀有天然产品的高灵敏度标记试剂。

几十年来，具有独特生物活性的稀有天然产物一直是理想的药物线索。然而，由于样品量的限制，它们的鉴定和结构确定是有问题的。受极其罕见的天然产物yaku'amide B（10）的启发，本研究设计并合成了高灵敏度的标记试剂，该试剂将成为稀有天然产物化学的有力工具。通过与10个结构修订的关键结构基序融合，在LC-MS分析中，氨基酸标记试剂的检测灵敏度大大提高。这些先进的标记试剂能够检测到极少量的氨基酸和肽水解产物。这种提高灵敏度的设计理念也适用于标记糖类的试剂和亲电性天然产物的反应导向分离。还提供了这些试剂的详细信息，包括其实际制备和扩展应用。