One new picrotoxane sesquiterpene (1) and one new α-pyrone derivative (4), together with nine known compounds, were isolated from the aerial parts of Dendrobium signatum. The structures of the new compounds were elucidated based on the interpretation of 1D and 2D NMR, HRESIMS and electronic circular dichroism (ECD) data. The absolute configuration of 1 was confirmed by single-crystal X-ray diffraction data. The new α-pyrone 4 exhibited promising ABTS scavenging activity with IC₅₀ value of 0.7 μM.

Graphic abstract

中文翻译：

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来自石斛的苦环烷倍半萜烯和α-吡喃酮衍生物及其自由基清除能力

从石斛的地上部分分离出一种新的苦环素倍半萜烯 ( 1 ) 和一种新的 α-吡喃酮衍生物 ( 4 )，以及 9 种已知化合物。基于一维和二维核磁共振、HRESIMS 和电子圆二色性 (ECD) 数据的解释阐明了新化合物的结构。通过单晶 X 射线衍射数据证实了1的绝对构型。新的 α-吡喃酮 4 表现出有希望的 ABTS 清除活性，IC ₅₀值为 0.7 μM。

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