Geissoschizine methyl ether N-oxide, a new oxindole alkaloid, along with 14 known alkaloids, was isolated from the aerial part of Uncaria rhynchophylla. Their structures were identified by comprehensive spectral methods, including 2D NMR experiments, and confirmed by comparing with the literature data. In vitro acetylcholinesterase (AChE) inhibitory activity assay showed that the new compound exhibited anti-AChE activity with IC₅₀ value of 23.4 μM.

中文翻译：

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Geissoschizine甲基醚N-氧化物，一种新的生物碱，具有抗乙酰胆碱酯酶的活性，来自钩藤（Uncaria rhynchophylla）。

从钩藤Uncaria rhynchophylla的地上部分中分离出一种新的羟吲哚生物碱Geososchizine甲基醚N-氧化物和14种已知生物碱。通过包括2D NMR实验在内的综合光谱方法鉴定了它们的结构，并与文献数据进行了比较证实。体外乙酰胆碱酯酶（AChE）抑制活性测定表明，该新化合物具有抗AChE活性，IC ₅₀值为23.4μM。