PREPARATION OF LIPIDE EXTRACTS FROM BRAIN TISSUE

Abstract

For the preparation of lipide extracts from tissues, the method of Bloor (I), either in its original form or with slight modifications, has been a standard procedure. This method consists in extracting the tissue with a mixture of ethyl alcohol and ether. Since the extract obtained is known to contain non-lipide contaminants, it is usually taken to dryness and the residue extracted with a solvent, such as chloroform or petroleum ether, which exhibits a highly specific solvent power for lipides. However, the secondary extracts obtained have been shown to contain substances other than lipides (2, 3). In the case of nervous tissue, it has been common experience that all of the lipides present in tissue are not extracted by Bloor’s procedure (4, 5). Thus, different workers have found it necessary to introduce a subsequent extraction of the tissue with another solvent of higher solvent power for lipides than Bloor’s mixture. This second solvent has usually been chloroform (4, 5). The methods thus developed are time-consuming, complicated, and, owing to the fact that they involve protracted treatment of the tissue with boiling solvents, they are open to the general objection that the procedure followed results in changing the chemical nature of some of the lipides. Furthermore, the extracts thus obtained are known to contain non-lipide contaminants (4, 5). This paper describes a simple method for the preparation of extracts of total pure lipides from brain tissue. The method consists of homogenizing the tissue with a chloroform-methanol mixture. The clear lipide extract thus obtained is then washed free of non-lipide contaminants by being placed in contact with a large amount of water. The whole procedure can be run at 0” and thus any danger of chemical changes in lipides is reasonably excluded.