Isolation and Structure Elucidation of GM4-Type Gangliosides from the Okinawan Starfish Protoreaster nodosus

Three new ganglioside molecular species, termed PNG-1, PNG-2A, and PNG-2B were isolated from pyloric caeca of the starfish Protoreaster nodosus. Their structures were elucidated using a combination of spectroscopic and chemical methods, and characterized as 1-O-[8-O-methyl-N-acetyl-alpha-neuraminosyl-(2 -> 3)-beta-galactopyranosyl]-ceramide for PNG-1, 1-O-[beta-galactofuranosyl-(1 -> 3)-alpha-galactopyranosyl-(1 -> 4)-8-O-methyl-N-acetyl-alpha-neuraminosyl-(2 -> 3)-beta-galactopyranosyl]-ceramide for PNG-2A, and 1-O-[beta-galactofuranosyl-(1 -> 3)-alpha-galactopyranosyl-(1 -> 9)-N-acetyl-alpha-neuraminosyl-(2 -> 3)-beta-galactopyr anosyl]-ceramide for PNG-2B. PNG-2A and PNG-2B represent the first GM4 elongation products in nature.