Twenty-six glucoconjugated monoterpene indole alkaloids, including 12 new compounds, rhynchophyllosides A-L (1-12), and 14 known ones, 13-26, were obtained from the hook-bearing stems of Uncaria rhynchophylla (Miq.) Miq. ex Havil. Their structures were unambiguously elucidated by analyses of UV, MS, NMR, ECD, and single-crystal X-ray diffraction data. The ESI-MSn behavior of the new glucoalkaloids was also elucidated. Although comprising the same glucosyl moiety, the aglycone skeletons and glucosidic numbers and linkage varied greatly, implying the diversity in biosynthetic pathways. This is the first report of such structurally diverse glucoconjugated monoterpene indole alkaloids from U. rhynchophylla. Compound 1 represents a new subtype of oxindole alkaloid with a seven-membered D-ring, 10 is a rare monoterpene indole alkaloid with the glucosyl moiety located at C-9, 4 and 5 are the first two oxindole alkaloid diglycosides, and 11 and 12 represent the first two examples of alkaloids with a quinolone nucleus from the genus Uncaria. Compound 10 exhibited moderate acetylcholinesterase (AChE) inhibitory activity with an IC50 value of 10.5 μM. Molecular docking was performed to explore the binding mode of inhibitor 10 at the active site of AChE.

中文翻译：

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钩藤Uncaria rhynchophylla的糖共轭单萜吲哚生物碱。

从钩藤Uncaria Rhynchophylla（Miq。）Miq的带钩茎中获得了二十六个糖缀合的单萜吲哚生物碱，包括12种新化合物，Rhychochophyllosides AL（1-12），和14种已知化合物13-26。前哈维尔。通过对UV，MS，NMR，ECD和单晶X射线衍射数据的分析清楚地阐明了它们的结构。还阐明了新的生物碱的ESI-MSn行为。尽管包含相同的葡萄糖基部分，但糖苷配基的骨架，糖苷的数量和键变化很大，这暗示了生物合成途径的多样性。这是来自U. rhynchophyllala的这种结构多样的葡糖共轭单萜吲哚生物碱的首次报道。化合物1代表具有七元D环的羟吲哚生物碱的新亚型，10是稀有的单萜吲哚生物碱，其葡糖基部分位于C-9，4和5是前两个氧吲哚生物碱二糖苷，而11和12代表前两个实例的生物碱，其具有来自钩藤属的喹诺酮核。化合物10表现出中等的乙酰胆碱酯酶（AChE）抑制活性，IC50值为10.5μM。进行分子对接以探索抑制剂10在AChE的活性位点的结合模式。