The monounsaturated acyl- and alkyl-moieties of wax esters and their distribution in commercial orange roughy (Hoplostethus atlanticus) oil

Wax esters were isolated from commercial orange roughy (Hoplostethus atlanticus) oil by column chromatography and fractionated by argentation thin layer chromatography. Following transesterification, the resultant fatty acid methyl esters and fatty alcohols were analyzed by gas chromatography. both acyl- and alkyl-moieties were mainly of the monoene structure within the 16∶1–22∶1 range. After derivatization, the positions of the double bonds of even numbered fatty acid and fatty alcohol isomers were located by chromatography-mass spectrometry and compared. Results of these positional analyses indicate that the primary desaturation reactions takes place in the Δ9 position of pre-existing (C₁₄ to C₂₄) acyl chains. It is proposed that acyl components from 18∶1 are subjected to chain elongation to form a mixture of 24∶1 isomers as the final product. Apart from the 24∶1 acyl moiety of the wax esters, in which the double bond was almost exclusively in the Δ15 position, de novo biosynthetic reactions on acids and alcohols appear to yield related acyl- and alkyl-moieties of resynthesized wax esters.