Identification of a C25 highly branched isoprenoid (HBI) diene in Antarctic sediments, Antarctic sea-ice diatoms and cultured diatoms

A highly branched isoprenoid (HBI) diene found in Antarctic sea-ice diatoms and surface layer (0–2 cm) sediments from Antarctica is identified as 2,10,14-trimethyl-6-methylene-7-(3′-methylpent-1-enyl)pentadecane. The identification was made by comparison of GC–MS mass spectra and retention indices on both polar and apolar GC stationary phases with those of the diene authenticated by NMR after isolation from a laboratory culture of the diatom, Haslea ostrearia.