Seventeen highly oxygenated and rearranged limonoids, including nine previously undescribed phragmalin-type limonoids with 1,8,9- and 8,9,30-orthesters (entanutilins C-K, 1-9), three undescribed limonoids with rare rearranged-6/6/7/5 skeleton (entanutilins L-N, 10-12), and 5 known limonoids, were isolated from the stem barks of Entandrophragma utile from Ghana (Africa). Their structures including absolute configurations were elucidated based on comprehensive spectroscopic analyses, such as HRESIMS, 1D/2D-NMR, CD exciton chirality method, time-dependent density functional theory (TDDFT)/ECD calculations, and single-crystal X-ray diffraction. Bioactivity screenings suggested that some of these compounds effectively reversed resistance in MCF-7/DOX cells at a nontoxic concentration of 30 μM with 6- to 19-fold enhancing effects.

中文翻译：

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来自 Entandrophragma utile 茎皮的高度氧化和重排的柠檬苦素

17 种高度含氧和重排的柠檬苦素，包括 9 种以前未描述的具有 1,8,9-和 8,9,30-邻位的 phragmalin 型柠檬苦素（entanutilins CK，1-9），三种未描述的具有罕见重排的柠檬苦素 - 6/6/ 7/5 骨架（entanutilins LN，10-12）和 5 种已知的柠檬苦素类化合物是从来自加纳（非洲）的 Entandrophragma utile 的茎皮中分离出来的。基于综合光谱分析，如 HRESIMS、1D/2D-NMR、CD 激子手性方法、时间相关密度泛函理论 (TDDFT)/ECD 计算和单晶 X 射线衍射，阐明了它们的结构，包括绝对构型。生物活性筛选表明，其中一些化合物以 30 μM 的无毒浓度有效逆转 MCF-7/DOX 细胞中的耐药性，并具有 6 至 19 倍的增强作用。