The cerebrosides of brain tissue

Abstract

Since the work of Thudichum, evidence has existed that there was more than one cerebroside. On the basis of physical properties and analyses, Thudichum distinguished two cerebrosides, phrenosin and kerasin. He had the correct intuition as to the points of difference of the two cerebrosides, and suggested that this difference was in the nature of one component, namely, the fatty acid. As far as he worked, the other components were identical in all cerebrosides. Unfortunately his method of separation was imperfect. Therefore, each fraction contained a large portion of the other. When the fatty acids were obtained, they analyzed approximately for a stearic acid, which Thudichum named neuro stearic acid. Subsequent workers improved the methods of purification particularly that of phrenosin; this permitted the isolation of the fatty acid, cerebronic acid. This acid was identified by Thierfelder as an hydroxy pentacosanic acid, C₂₅H₅₀O₃. The further work on cerebrosides brought nothing new as regards their structure. The attempt of Thierfelder to classify them on the basis of their sugar contents was futile. Finally, it was possible to isolate from a cerebroside corresponding to Thudichum's kerasin, a fatty acid of different structure from cerebronic acid, namely, lignoceric acid. This acid was isolated nearly simultaneously in three laboratories, but its relation to cerebronic and lignoceric acids was first established in our laboratory, and independently of us by Rosenheim. Since then, it has been possible to judge of the purity of a cerebroside by the composition of the fatty acid fraction obtained on hydrolysis. This standard has been employed by us in testing the purity of the substance designated as phrenosin and kerasin.

By methods employed in different laboratories, it has been possible to obtain phrenosin in a fair degree of purity.