Structural analysis of leech galactocerebrosides using 1D and 2D NMR spectroscopy, gas chromatography mass spectrometry, and FAB mass spectrometry

摘要

Cerebrosides were isolated from the leech species, Hirudo medicinalis, and purified to homogeneity by silicic acid chromatography, followed by preparative thin-layer chromatography. Their structure was determined by spectroscopic and chemical methods. 1D and 2D H-1 NMR spectroscopy, DQF-COSY and HMQC indicated that the head group consists of a single galactose residue in the beta configuration. The galacto configuration was determined by the characteristic chemical shift, the spin-spin splitting and the multiplicity of the characteristic resonance of its equatorial H-4 proton, as well as by the splittings of the other ring protons. GC, GC-MS and fast-atom-bombardment mass spectrometry studies indicated that C-24:0 and C-22:0 are the major saturated fatty acid species. Unsaturated fatty acids present were C-25:2, C-27:2, C-27:3, C-28:3, C-29:3, C-30:3, C-33:3 GC-MS indicated the presence of hydroxylated C-27:2 and one other unidentified hydroxylated fatty acid. The cerebroside contained an unusual polyunsaturated sphingosine analogue, namely 2-amino-1,3-dihydroxydocosatriene. (C) 1998 Elsevier Science Ltd. All rights reserved. [References: 22]