Isolation and structure of a monomethylated ganglioside possessing neuritogenic activity from the ovary of the sea urchin Diadema setosum

A new monomethylated ganglioside, DSG-A (3), was obtained, together with four known gangliosides, compounds (1, 2, 4, 5), from the lipid fraction of the chloroform/methanol extract of the ovary of the sea urchin Diadema setosum. The structures of the new ganglioside was determined on the basis of chemical and spectroscopic evidence to be 1-O-[9-O-methyl-(N-acetyl-α-D-neuraminosyl)- (2→6)-β-D-glucopyranosyl]-ceramide (3). The ceramide moiety of 3 was composed of C₁₈-phytosphingosine base, and 2-hydroxy and nonhydroxylated fatty acid units. These gangliosides showed neuritogenic activity toward the rat pheochromocytoma cell line PC-12 in the presence of nerve growth factor, in which compound 3 showed the most potent activity.