Gangliosides with sialic acid bound to N-acetylgalactosamine from hepatopancreas of the starfish, Evasterias retifera and Asterias amurensis

Abstract

Sialoglycolipids containing glucose, galactose, N-acetylgalactosamine and sialic acids were isolated from the total lipid extracts of hepatopancreas of the starfish, Evasterias retifera and Asterias amurensis, by partition dialysis, DEAE-cellulose column chromatography and preparative silica gel TLC. The structures of the sialoglycolipids were established by total and partial acid hydrolysis, total and partial methanolysis, methylation analysis, periodate oxidation, neuraminidase treatment and chromium trioxide oxidation. The sialoglycolipid from E. retifera was identified as N-acetylneuraminosyl- α-(2 → 9)- N-acetylneuraminosyl- α-(2→3- N -acetylgalactosaminyl- β -(1 → 3)-galactosyl- β-(1 → 4)-glucosyl- β -(1 → 1)-ceramide and that from A. amurensis was identified as 8- O-methyl- N-glycoloylneuraminosyl-(2 →3)-(8- O-methyl- N-glycoloylneuraminosyl-(2 → 6))- N-acetylgalactosaminyl- β-(1 → 3)-galactosyl- β-(1 → 4)-glucosyl- β-(1 → 1)-ceramide. The long-chain bases of both sialoglycolipids were found to be mixtures of phytosphingosines with both branched and linear structures and the fatty acids were shown to be mixtures of normal and α-hydroxy fatty acids. The composition of the lipid moieties of the sialoglycolipids was determined by GLC and GLC-MS.