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Metabolism of arachidonate in rat testis: Characterization of 26–30 carbon polyenoic acids
Author(s) -
Grogan W. McLean
Publication year - 1984
Publication title -
lipids
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.601
H-Index - 120
eISSN - 1558-9307
pISSN - 0024-4201
DOI - 10.1007/bf02534785
Subject(s) - isomerization , chemistry , double bond , arachidonic acid , fatty acid , high performance liquid chromatography , chromatography , metabolism , polyunsaturated fatty acid , lipidology , carbon fibers , carbon number , gas chromatography , metabolite , biochemistry , stereochemistry , organic chemistry , catalysis , enzyme , materials science , alkyl , composite number , composite material
Fatty acid methyl esters of long‐chain polyenoic fatty acids (LCPA) from rat testis injected with [1‐ 14 C] arachidonate were analyzed and separated by reversed‐phase high performance liquid chromatography (RP‐HPLC). Earlier, all previously identified LCPA were prepared in high purity along with 4 previously unidentified fatty acids, which were further characterized by capillary gas chromatography (GC), catalytic hydrogenation and alkaline isomerization. Unidentified fatty acids proved to be 26∶4, 26∶5, 28∶5 and 30∶5. All of these LCPA incorporated 14 C from arachidonate (20∶4) to specific activities that were comparable to that of 20∶4 and previously identified metabolites of 20∶4 and much greater than specific activities of 18∶1n−9 or 22∶6n−3. LCPA were analyzed on a capillary GC system capable of resolving known cis‐trans and positional isomers of the n−3, n−6, n−7 and n−9 families of unsaturated fatty acids. Log plots of isothermal retention times and normal plots of temperature programmed retention times were linear (r=0.999) in carbon number when values for known and previously unidentified LCPA of 4 or 5 double bonds, respectively, were coplotted. Thus, the newly identified fatty acids belong to the n−6 family of fatty acids synthesized from arachidonic acid.