Immunomodulatory-Galactoglycosphingolipids : Synthesis of 2'-Fluoro-2'-deoxy--galactosylceramide and an Evaluation of Its Immunostimulating Properties

In the framework of a project to assess the immunomodulating properties of α-galactosyl glycosphingolipids, the total synthesis of 1-O-(2-fluoro-2-deoxy-α-D-galactopyranosyl)-2-docosanoylamino-1,3, 4-octadecanetriol (1), a 2′-fluoro analogue of the immunostimulating α-galactoglycosphingolipids, was accomplished. The glycosidation reaction of the azido precursor of sphingosine was performed using the Mukaiyama glycosidation reaction. The stimulation of mouse splenocyte proliferation by the 2′-fluoro analogue was highly reduced compared to that of the α-galactoglycosphingolipids, thereby confirming that a free galactose 2-OH group is essential for the immunostimulatory activity.