1P-39 PDF
Diversity of glycosylated sterols in brain – Complete structural determination of glucosylated cholesterol and sitosterol
Sterylglycosides are glycosylated sterols and have been reported in bacteria, fungi, plants, and animals. In animals, cholesterol is glucosylated to form cholesterylglucoside (β-GlcChol). We found that β-GlcChol biosynthesis in animals is facilitated by the transglucosylation reaction of β-glucocerebrosidase 1 (GBA1) or 2 (GBA2), utilizing glucosylceramide as a glucose donor. Impaired GBA1 or GBA2 function is associated with neurological disorders, such as cerebellar ataxia, spastic paraplegia, and Parkinson’s disease. The presence of β-GlcChol in mouse brain has been inferred by liquid chromatography-mass spectrometry. However, purification of β-GlcChol from the brain and its complete structural analysis had not been reported. In this study, we prepared highly enriched sterylglucoside from embryonic chicken brains utilizing a novel three-step chromatographic procedure, and confirmed the presence of β-glucosidic linkage by 1H-NMR analysis. Although cholesterol had been believed to be the sole sterol backbone structure of animal sterylglucoside, two additional sterylglucosides were isolated during the purification. In addition to the major component featuring the expected cholesteryl aglycon, two more steryl aglycons including the plant-type sitosteryl were identified. Our work is the first report of the complete structure of β-GlcChol and β-sitosterylglucoside derived from vertebrate brain with MALDI-MS/MS, uncovering unexpected aglycon heterogeneity of sterylglucosides in vertebrate brain.