CHEMICAL BEHAVIOR OF CYTIDINE 5'-MONOPHOSPHO-N-ACETYL-BETA-D-NEURAMINIC ACID UNDER NEUTRAL AND ALKALINE CONDITIONS

The chemical behavior of CMP-N-acetylneuraminic acid under neutral and different alkaline conditions was investigated. The products formed were isolated by ion-exchange chromatography and gel filtration, and analyzed by colorimetric methods, TLC, combined GLC/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-.beta.-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.