Separation and Isolation of Methyl Esters and Dimethylacetals Formed from Brain Lipids.

THE PROCEDURE of Stoffel, Chu, and Ahrens (1) for preparing and separating the methyl esters of fatty acids and the dimethylacetals (DMA) when applied to brain lipid extracts proved adequate for the nonoxygenated fatty acids and DMA. Some of the cholesterol in the extract, however, was converted to derivatives, one of which, A3kholestadiene (2), sublimed along with the methyl esters and the DMA. Furthermore, it was found that under the conditions specified by Stoffel et al. (l), approximately 75% of the 2-hydroxy methyl esters remained unsublimed. Reports (3-5) on the fractionation and estimation of nonoxygenated and oxygenated fatty acid derivatives suggest that a thin-layer chromatographic procedure (TLC) could be developed to separate quantitatively the esters of the nonoxygenated and of the 2-hydroxy fatty acids as well as of the DMA. This consideration and the possibility that cholesterol and its derivatives could be separated were explored. Chimyl alcohol, glyceryl monostearate, 12-hydroxy stearic acid, behenic acid, 2-hydroxy behenic acid, oleyl and behenyl alcohols, nonoxygenated methyl esters,'