Abstract A novel tri-unsaturated C25 highly branched isoprenoid (HBI) alkene has been identified in a laboratory culture of the diatom Navicula salinicola and its structure determined using a combination of NMR spectroscopy and gas chromatography–mass spectrometry (GC–MS). This represents the first report of a C25 HBI in a marine diatom from the Navicula genus, although a different tri-unsaturated C25 HBI has been reported previously in the freshwater species N. sclesvicensis and unspecified HBIs have been identified in the brackish N. phyllepta. The newly characterised HBI contains a relatively unusual conjugated diene sub-unit, a structural feature only previously reported in some HBIs biosynthesised by a further marine diatom, Haslea ostrearia.

中文翻译：

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来自海洋硅藻 Navicula salinicola 的新型三不饱和高度支化类异戊二烯 (HBI) 烯烃

摘要 在硅藻 Navicula salinicola 的实验室培养物中鉴定出一种新型三不饱和 C25 高度支化类异戊二烯 (HBI) 烯烃，并结合使用核磁共振光谱法和气相色谱-质谱法 (GC-MS) 确定了其结构。这代表了舟形藻属海洋硅藻中 C25 HBI 的首次报告，尽管之前在淡水物种 N. sclesvicensis 中报道了不同的​​三不饱和 C25 HBI，并且在微咸水 N. phyllepta 中发现了未指定的 HBI。新表征的 HBI 包含一个相对不寻常的共轭二烯亚基，这种结构特征之前仅在由进一步的海洋硅藻 Haslea ostrearia 生物合成的一些 HBI 中报道过。