New Techniques for the Investigation of Structure and Metabolism of Sialic Acids

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Abstract
Sialic acids are derivatives of neuraminic acid with either an acetyl or glycolyl residue at the amino function and frequently one or more O-acetyl group(s) at C-4, C-7, C-8 and preferably at C-9. C-9 can also be O-lactylated and C-8 O-methylated.1,2 Sialic acids are usually determined by colorimetry,3 fluorimetry,4 thin-layer and gas-liquid chromatography.3, 5 Structural analysis is performed by gas-liquid chromatography combined with mass spectrometry (GLC-MS)3 or by 1H-nuclear magnetic resonance spectroscopy.6 Most of these methods require purification of the neuraminic acid derivatives, which is time-consuming and may lead to loss of sialic acids and hydrolysis or migration of O-acetyl groups.7 In GLC analysis the derivatization procedure used so far has sometimes failed to give the expected derivatives, or these were not stable. Furthermore, due to insufficient separation on packed columns, quantitative determination was not satisfactory, either.