Euphnerins A (1) and B (2), two extremely modified diterpenoids possessing an unprecedented 5/6/6 rearranged spirocyclic carbon skeleton, and a biosynthetically related known diterpenoid (3) were purified from the stems of Euphorbia neriifolia. Their structures were identified by NMR experiments and X-ray diffraction analysis, as well as experimental and calculated electronic circular dichroism data comparison. A putative biosynthetic relationship of 1 and 2 with their presumed precursor 3 is proposed. Compound 1 showed NO inhibitory effects in lipopolysaccharide-stimulated BV-2 cells with an IC₅₀ value of 22.4 μM.

中文翻译：

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Euphnerins A 和 B，来自大戟属植物茎的具有 5/6/6 重排螺环碳骨架的二萜。

Euphnerins A ( 1 ) 和 B ( 2 )，两种极其修饰的二萜类化合物，具有前所未有的 5/6/6 重排螺环碳骨架，以及一种生物合成相关的已知二萜类化合物 ( 3 ) 从大戟的茎中纯化出来。它们的结构通过核磁共振实验和 X 射线衍射分析，以及实验和计算电子圆二色性数据比较确定。提出了1和2与其假定的前体3 的假定生物合成关系。化合物1在脂多糖刺激的 BV-2 细胞中显示 NO 抑制作用，IC ₅₀ 值为 22.4 μM。