Saturated and olefinie hydrocarbons were determined in additional species of benthic marine algae from the Cape Cod (Massachusetts, USA) area (see: Youngblood et al., t97t).
The distribution of homologous and isomeric olcfins was studied in plants of different age and in morphologically different parts of the same specimen. With two minor exceptions, only normal alkanes and alkenes are present. The methyleneinterrupted C19 -and C21-polyolefins are particularly abundant; Al-heneicosahexaene and the corresponding pentaene are common to all brown algae, while the corresponding A~-isomers occur in green algae. The hydrocarbon concentration, the alkenc-to-alkane ratio and the polyolefin content are highest in young plants or in rapidly growing tissues of older plants. This suggests a deeper involvement in cell biochemistry of straight-chain hydrocarbons than previously considered. The biosynthesis of the plant polyolefins remains to be explored; no immediately obvious precursors of the A~-polyolefins were found among the algal fatty acids. The hydrocarbon composition of these benthic algae differs greatly from that of fossil fuels in its simplicity and predominately unsaturated nature. The separation of the isomers by gas chromatography and their structural elucidation by mass spectrometry, ~lone and in combination with hydrogenation and ozonolysis, are discussed. legatine ]3iology, Vol.