Glycosphingolipids in insects

Abstract

The two major components of the acidic glycolipid fraction from the pupae of Calliphora vicina were isolated using high‐performance liquid chromatography. The acidic moiety was identified as glucuronic acid by β‐glucuronidase cleavage and gas chromatographic analysis as the pentafluoropropionyl derivative. The structures of the carbohydrate moiety were elucidated by peracetylation, methylation, exoglycosidase cleavage, fast‐atom‐bombardment mass spectrometric and ¹H‐nuclear magnetic resonance spectroscopic analysis. The only difference between the two hexasaccharide variants was the presence, in one of them, of a phosphoethanolamine (AeP) sidechain on the third sugar of the sequence, i. e. N‐acetylglucosamine. The composition of the ceramide moiety was dominated by a C₂₀:₀ fatty acid (arachidic acid) and a C₁₄:₁ sphingoid base (tetradecasphing‐4‐enine). The chemical structures of the two insect acidic glycosphingolipids were determined to be: GlcA(β‐3)Gal‐(β1‐3)GalNAc(β1 ‐4)GlcNAc(β1 ‐3)Man(β1‐4)Glc(β ‐1)Cer; GlcA(β1‐3)Gal(β1‐3)GalNAc(β1 ‐4)[2AeP‐6]‐GlcNAc(β1‐3)Man(β1 ‐4)Glc(β1‐1)Cer. Such glucuronic‐acid‐containing insect glycosphingolipids have been given the generic name arthrosides, with the implied synonymity to the gangliosides.