Calculation of ECL values in the gas-liquid chromatography of multiple-branched fatty acids

Novel branched-chain fatty acids in certain fish oils

Methyl-branched fatty acids, which are usually minor components (equal or less than 0.1%) in fish oils, were concentrated in the non-urea-complexing fraction along with polyunsaturated fatty acids during the enrichment of omega-3 fatty acids from certain fish oils via the urea complexation process. The methyl-branched fatty acids in the omega-3 polyunsaturated fatty acid concentrates, which were prepared from three fish body oils, were characterized by gas chromatography and gas chromatography/mass spectrometry. Among the major branched-chain fatty acids expected and identified were the known isoprenoid acids--mainly 4,8,12-trimethyltridecanoic, pristanic, and phytanic--and the well-known iso and anteiso structures. Two novel phytol-derived multimethyl-branched fatty acids, 2,2,6,10,14-pentamethylpentadecanoic and 2,3,7,11,15-pentamethylhexadecanoic, were identified in redfish (Sebastes sp.) oil. These two fatty acids were absent in oils from menhaden (Brevoortia tyrannus) and Pacific salmon (mixed, but mostly from sockeye, Oncorhynchus nerka). The major branched-chain fatty acid in the salmon oil, 7-methyl-7-hexadecenoic acid, was also present to a moderate extent in menhaden oil. A novel vicinal dimethyl-branched fatty acid, 7,8-dimethyl-7-hexadecenoic was detected in all of the fish oils examined, but was most important in the salmon oil. Three monomethyl-branched fatty acids, 11-methyltetradecanoic acid, and 11- and 13-methylhexadecanoic, hitherto undescribed in fish lipids, were also detected in salmon, redfish and menhaden oils.

Identification of methyl-branched fatty acids from the triacylglycerols of subcutaneous adipose tissue of lambs

A concentrate of branched chain fatty acids (as methyl esters) was prepared from the triacylglycerols of subcutaneous adipose tissue lipids of lambs receiving a carbohydrate-rich (cereal diet). This was accomplished by procedures which allowed the removal of unsaturated components by peroxidation and straight chain saturated components by urea-adduct formation. The concentrate was analyzed by high resolution gas chromatography in combination with mass spectrometry and was shown to consist of a complex mixture of saturated methyl-substituted fatty acids. Methyl substitution occurred on even-numbered carbon atoms (relative to the carboxyl group) and the chain lengths of the acids ranged from 10 to 18 carbon atoms. Acids with one methyl substituent in the fatty acyl chain were most abundant; di-, tri- and tetramethyl-substituted acids were also present. The biosynthesis of these methyl-substituted acids is discussed briefly.

A new cerebroside from Fusicoccum amygdali Del

A homogeneous cerebroside was isolated from a strain of Fusicoccum amygdali Del., a fungus pathogenic to almond and peach. Chemical degradations, together with extensive application of nuclear magnetic resonance and mass spectrometry techniques, led to elucidation of its structure. This corresponds to N-2'-hydroxy-3'-trans-octadecenoyl-1-O-beta-D-glucosyl-9-methyl-cis-4,x-8-sphingadienine.

Characterization of branched-chain fatty acids from fallow deer perinephric triacylglycerols by gas chromatography-mass spectrometry

Branched-chain fatty acids of perinephric triacylglycerols of semi-feral fallow deer (Dama dama dama) were analyzed by high resolution gas chromatography-mass spectrometry. Of the total fatty acids, 15.50% were Branched-chain components including 8.96% iso acids, mostly 14-methylpentacanoic acid, 2.85% anteiso acids and 1.73% of other monomethyl-substituted acids; dimethyl-branched acids with an iso structure (1.05%) and with an anteiso structure (0.18%) were also present. Whereas the predominant iso acids and methyl-substituted iso acids had chain lengths of 13 and 15 carbon atoms, the anteiso acids and methyl-substituted anteiso acids had chain lengths of 14 and 16 carbon atoms. Methyl substitution occurred on the even numbered carbon atoms relative to the carboxyl group. The general composition is also given of the fatty acids comprising the triacylglycerols of subcutaneous (rump area) and perinephric adipose tissue.

Fatty acids. II. The synthesis and gas-liquid chromatographic behaviour of five trimethylene-interrupted C18-diunsaturated fatty acids

Five trimethylene-interrupted methyl octadecadiynoates, C18 delta-2a,-7a; delta-3a,-8a; delta-4a,-9a; delta-5a,-10a and delta-6a,-11a, and the corresponding cis,cis-octadecadienoates were synthesized, and their gas-liquid chromatographic properties were studied on Apiezon L, diethylene glycol succinate polyester and Silac 10C stationary phases. The equivalent chain lengths of these esters have been determined, and the separation of mixtures and the prediction of gas chromatographic behaviour of these isomers are discussed.