Isolation and structure of monomethylated GM₃-Type ganglioside molecular species from the starfish Luidia maculata

Two monomethylated GM₃-Type ganglioside molecular species, 1 and 2, have been obtained from the polar lipid fraction of the chloroform/methanol extract of the starfish Luidia maculata. The structures of these gangliosides have been determined on the basis of chemical and spectroscopic evidence as 1-O-[8-O-methyl-(N-acetyl-α-D-neuraminosyl)-(2→3)-β-D- galactopyranosyl-(1→4)-β-D-glucopyranosyl]-ceramide (1) and 1-O-[8-O-methyl-(N-glycolyl-α-D-neuraminosyl)-(2→3) -β-D-galactopyranosyl-(1→4)-β-D-glucopyranosyl]-ceramide (2). The ceramide moieties were composed of heterogeneous unsubstituted fatty acid, 2-hydroxy fatty acid, sphingosine and phytosphingosine units. Compound 1, designated as LMG-3, represents new ganglioside molecular species. Compound 2 was a known ganglioside molecular species.