Structure and amount of positional isomers of monounsaturated fatty acids in human depot fat.

Positional isomers of decenoic, dodecenoic, and tetradecenoic acids of human adipose tissue have been separated by gas-liquid chromatography and their amounts determined by oxidative cleavage. The following acids have been shown to be present: 7-decenoic, 8-decenoic, 9-decenoic, 7-, 8-, and 9-dodecenoic, and 7-, 8-, 9-, and 11-tetradecenoic acids. Among all isomers of the even-numbered acids from C(10) to C(18) the cis-9-isomer predominates. With increasing chain length, however, the content of 9-isomer decreases and the number of isomers increases. No 3- or 5-enoic acids could be detected. The origin and biosynthesis of all isomers are discussed.