Abstract

Spectroscopic analysis ofmutarotatedmethyl(-d-glucopyranosyluronate)-(1ï�?®3)-2-amino-2-deoxy-D-galactopyranose in aqueous solution

Author(s): Hammed.H.A.M.Hassan

Chondrosine [-D-GlcpA-(13)-,-D-GalNH2] is a natural disaccharide accessible fromChondroitin sulfate (CS).We report in this communication the 1H and 13C NMR spectral data of the chondrosine methyl ester (3) in D2O. Data revealed that two isomers of (3) namely methyl [-D-GlcpA- (13)-,-D-GalNH2] (3a) andmethyl [-D-GlcpA-(13)-,-D-GalNH2] (3b) are present in solution and undergoing mutarotation on the GalNH2 reducing end. Since the glycosidic linkage of the GlcpA residue can not undergo interconversion, it is rational to conclude that the  anomers of this residue are either generated in an early step during the preparation of chondrosine itself or both are natural products. This is the first experimental evidence for the presence of two combinations of mutarotated condrosine methyl ester in aqueous solution and thus the  designation can be made for the GlcpA residue in (3).