Abstract
The structural characterization of the 2-hydroxy monounsaturated fatty acids of pig brain sphingolipids is described. The acids were isolated via the copper chelate and converted to the 2-methoxy methyl esters. The ether esters were separated using column, thin-layer, and gas-liquid chromatography, and the positions of the double bonds were determined by oxidative ozonolysis. Seventeen chemically defined hydroxy acids were found, 15 of which have not been previously reported. These include the odd- and even-numbered hydroxy acids 22 to 26 carbon atoms long. Each acid consisted of three to four positional isomers which appear to have been derived from the corresponding non-hydroxy unsaturated acids. The proportion of isomers in the hydroxy acids structurally related to palmitoleate (ω7) was higher than in the non-hydroxy monoenoic acids. Components tentatively identified as 2-hydroxy dienoic acids, 22 to 26 carbons long, and 27h:1 were found by gas-liquid chromatography, and small amounts of 2-hydroxy trienoic acids were also tentatively identified by thin-layer chromatography of the mercuric acetate adducts.
Highlights
RECENTLY WE HAVE examined the unsaturated nonhydroxy fatty acids of pig brain sphingolipids by a combination of silver nitrate-silica gel chromatography, GLC,' and ozonolysis [1]
From the positions of the double bonds, it appeared that most of the acids were formed from oleic, palmitoleic, linoleic, Abbreviations used: DEGS is a polymeric form of diethyleneglycol succinate; SE-30 is a General Electric silicone gum; SkB is SkellysolveB, a commercial hexane from Skelly Oil Co., Kansas City, Missouri; TLC is thin-layer chromatography; GLC is gasliquid chromatography
The first number indicates the chain length, the second number indicates the number of double bonds, the superscripts indicate the positions of the double bonds, h indicates a 2-hydroxy group, and d indicates the acid is an a, w-dicarboxylic acid
Summary
RECENTLY WE HAVE examined the unsaturated nonhydroxy fatty acids of pig brain sphingolipids by a combination of silver nitrate-silica gel chromatography, GLC,' and ozonolysis [1]. 2 6 dienes, and each acid consisted of two to four positional isomers. From the positions of the double bonds, it appeared that most of the acids were formed from oleic, palmitoleic, linoleic, Abbreviations used: DEGS is a polymeric form of diethyleneglycol succinate; SE-30 is a General Electric silicone gum; SkB is SkellysolveB, a commercial hexane from Skelly Oil Co., Kansas City, Missouri; TLC is thin-layer chromatography; GLC is gasliquid chromatography. The position of a fatty acid double bond, as measured from the wend, is indicated by a prefixed w, as in w7. Apparatus, and procedures employed in this study have been described previously [1]
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