Direct electrospray-ionization mass spectrometric analysis of the major ganglioside from crucian carp liver after thin layer chromatography

Ganglioside patterns from crucian carp brain, muscle, and liver as well as liver gangliosides of roach, carp, the cichlid Oreochromis mossambicus, pig eon, dwarf hamster, and calf were comparatively analyzed by high performanc e thin layer chromatography (HPTLC). To achieve a rapid estimation on poten tially interesting ganglioside compounds, electrospray-ionization mass spec trometry (MS) was directly applied to a chloroform/methanol extract of the major TLC band of crucian carp liver. The spectrum, obtained from a few mic rograms of this crude biological sample, revealed a series of peaks corresp onding to GM4-like monosialoganglioside species. GC-MS analysis revealed hy droxylated fatty acids ranging from 2 h 20 min:0 to 2 h 26 min:0 for the [M 'H](-) ions of m/z 1061-1145. Collision induced dissociation tandem MS/MS o f the major peak with a [M'H] ion of m/z 1117 demonstrated the presence of N-acetylneuraminic acid as sialic acid compound. The sugar composition was confirmed by GLC as galactose and sialic acid in a 1:1 molar ratio. Thus, t he structure of the ion at mit 1117 is N-acetylneuraminylgalactosylceramide (NeuAc-Gal-Cer) with the long chain base d18:1 and the hydroxylated fatty acid 2 h 24 min:0. The results demonstrate for the first time unambiguously that NeuAc-Gal-Cer is the main ganglioside fraction in fish liver and that electrospray ionization-mass spectrometry (ESI-MS) can be used to elucidat e the chemical composition of a ganglioside fraction obtained by convenient extraction of a HPTLC band. (C) 1999 Elsevier Science Inc. All rights rese rved.