Ganglioside lactones:1H-NMR determination of the inner ester position of GD1b-ganglioside lactone naturally occurring in human brain or produced by chemical synthesis

The complete definition of the chemical structure of GD1b-ganglioside (GD1b) lactone isolated from human brain has been given by means of spectrometric and spectroscopic analyses. GD1hlactone contains a single ester linkage involving the external sialic acid carboxyl group and the C-9 hydroxyl group of the internal sialic acid unit. A synthetic lactone of GD1bprepared treating GD1bwith glacial acetic acid characterized in the same way showed an identical chemical structure.