A novel tri-unsaturated highly branched isoprenoid (HBI) alkene from the marine diatom Navicula salinicola

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.