A detailed chemical investigation of the South China Sea nudibranch Hexabranchus sanguineus, as well as its possible sponge-prey Acanthella cavernosa, led to the isolation of fifteen new nitrogenous sesquiterpenoids, namely ximaocavernosins A−O, including seven cadinanes (1—7), seven spiroaxanes (12—18) and one aromadendrane (19), together with thirteen known related compounds (8—11 and 20—28). Compounds (±)-1—9 (except for 4 and 6) were further separated by chiral-phase HPLC to their corresponding unequal enantiomers, respectively. Their structures and absolute configurations were determined by a combination of extensive spectroscopic data analysis, quantum mechanical nuclear magnetic resonance (QM-NMR) methods, Mosher's method, X-ray diffraction analysis and/or time-dependent density functional theory/electronic circular dichroism (TDDFT-ECD) calculation. The commonly existed nitrogenous sesquiterpenoids in these two animals are suggested to be chemical markers for their prey-predator relationship.

中文翻译：

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来自南海裸鳃亚目 Hexabranchus sanguineus 的含氮倍半萜类及其可能的海绵猎物海绵状棘突：手性分离、立体化学和化学生态学

对南海裸鳃类动物 Hexabranchus sanguineus及其可能的海绵猎物Acanthellacabernosa的详细化学调查，导致分离出 15 种新的含氮倍半萜类化合物，即 ximaocavernosins A-O，包括 7 种卡地烷 (1-7)、7 种螺环烷 (12-18) 和一种芳香树烷 (19)，以及 13 种已知的相关化合物 (8-11)和 20-28）。化合物(±)-1-9（4和6除外）分别通过手性相HPLC进一步分离为相应的不等对映异构体。它们的结构和绝对构型是通过广泛的光谱数据分析、量子力学核磁共振 (QM-NMR) 方法、Mosher 方法、X 射线衍射分析和/或瞬态密度泛函理论/电子圆二色性的组合确定的。 TDDFT-ECD) 计算。