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Isolation of natural arachidonic acid as its methyl ester

1951; Wiley; Volume: 28; Issue: 2 Linguagem: Inglês

10.1007/bf02612091

1558-9331

S. F. Herb, R. W. Riemenschneider, Jeanette Donaldson,

Metabolomics and Mass Spectrometry Studies

Summary Fresh beef suprarenal glands were ground and extracted thoroughly with alcohol and then with ethyl ether. After removal of solvent the total lipid residue was saponified, and the fatty acids were recovered by extraction. The less unsaturated acids were removed by crystallization from acetone at −40°C. At this stage the filtrate contained essentially all the arachidonic acid originally present in the glands and also unsaponifiable matter. After the unsaponifiable material was removed, the arachidonic acid content of the concentrate was about 25%. These unsaturated acids were converted to their methyl esters and fractionated on a silicic acid adsorption column. The progress of the adsorption fractionation was followed by spectrophotometric examination and determination of iodine values of the eluted fractions. Methyl arachidonate of 90% purity was obtained by this means. It was further purified by fractional distillation in vacuo. The final product had an iodine value of 316.1; theory, 318.8. The purity of this preparation was further established by spectrophotometric examination, by saponification equivalents, mean molecular weight, and by x‐ray diffraction patterns and melting points of a completely hydrogenated portion. Evidence of acids of greater unsaturation than arachidonic acid in suprarenal lipids was also clearly established by spectrophotometric examination. A fraction was obtained which was estimated to contain about 80–85% of a C 20 acid with five double bonds.