Chemical behaviour of cytidine 5′‐monophospho‐N‐acetyl‐β‐d‐neuraminic acid under neutral and alkaline conditions

Abstract

The chemical behaviour of CMP‐N‐acetylneuraminic acid under neutral and different alkaline conditions has been investigated. The products formed were isolated by ion‐exchange chromatography and gel filtration and analysed by colorimetric methods, thin‐layer chromatography, combined gas‐liquid chromatography/mass spectrometry and/or 360‐MHz ¹H‐NMR spectroscopy. A maximum stability of CMP‐N‐acetylneuraminic acid was observed at pH 8–11. In the tested pH range of 6–13, CMP and N‐acetylneuraminic acid were formed in variable amounts as decomposition products. 2‐Deoxy‐2,3‐dehydro‐N‐acetylneuraminic acid was produced at pH > 7; the amount of this substance increased with increasing pH. In anhydrous triethylamine its yield was 50%. A new neuraminic acid derivative, N‐acetyl‐β‐d‐neuraminic acid 2‐phosphate, could be isolated from the mixture of alkaline decomposition products of CMP‐N‐acetylneuraminic acid. The yield of this compound was maximum 22% in anhydrous triethylamine. Because 2‐deoxy‐2,3‐dehydro‐N‐acetylneuraminic acid was formed under simulated physiological conditions, it is assumed that this compound, which occurs in tissues and fluids of man and animals, is derived from CMP‐N‐acetylneuraminic acid non‐enzymically also under conditions in vivo.