Isolation of Less Polar Alkali-Labile Glycolipids of Human Brain by High-Speed Countercurrent Chromatography

Abstract

High-speed countercurrent chromatography (HSCCC), a liquid-liquid partition system, was used for the final purification of less polar alkali-labile glycolipids (ALGLs) of human brain. It has been reported that vertebrate brain contains ALGLs consisting of ester cerebroside and monoglucosyldiacylglycerol. ALGLs have alkali-labile ester bonds and are shown to be less polar than cerebroside.

First, ALGLs (ALGL-I, II, III and IV) were extracted and isolated by repeated silica gel column chromatography. Then, the mixture of ALGLs was subjected to the HSCCC in which a solvent system, hexane/ethanol/water (5:4:1, by volume), was used with the lower phase mobile. ALGL-IV and -III were clearly separated. ALGL-IV, which was resolved as a single band on high performance thin-layer chromatography, was further separated into several components (ALGL-IVa, b, c, d and e). This is the first application of HSCCC for the separation of human brain ALGLs. The availability of purified ALGLs provides an opportunity to determine their structure, metabolic pathway, and function in relation to human health and disease.