Inhibiting human astrocytoma growth: structure-activity relationships in neurostatin related glycolipids.

Neurostatin, a mammalian brain inhibitor of division of astroblast and astrocytoma cells, was characterized as the disialoganglioside GD1b, 9-O-acetylated on the outer sialic acid residue (Galbeta1-->3GalNAcbeta1-->4(9-O-Ac-NeuAcalpha2-->8NeuAcalpha2-->3)Galbeta1-->4Glcbeta1-->1'-ceramide). Using semisynthetic approaches, we prepared and tested different gangliosides O-acetylated in the sialic acid and compared them to non-O-acetylated partners as inhibitors of U-373 glioma cells. Athough the O-acetylation of the sialic acid was the most important molecular feature for the antiproliferative activity of O-acetylated gangliosides, monosaccharide links Galbeta1--> 3GalNAcbeta1 and NeuAcalpha2-->8NeuAcalpha2 enhanced the inhibitory activity.