Classification into a Novel Mollu-Series of Neutral Glycosphingolipids from the Lamp Shell, Lingula unguis¶

Abstract

Seven neutral glycosphingolipids were isolated and purified from the lamp shell, Lingula unguis by successive column chromatography on ion exchange Sephadex (QAE-Sephadex), magnesium silicate (Florisil) and silicic acid (Iatrobeads). Their chemical structures were characterized as Glcβ1-1ceramide (CMS₁, CMS₂ and CMS₃), Manβ1-4Glcβ1-1ceramide (MlOse₂Cer, CDS), Manα1-3Manβ1-4Glcβ1-1ceramide (MlOse₃Cer, CTS), GlcNAcβ1-2Manα1-3Manβ1-4Glcβ1-1ceramide (MlOse₄Cer, CQS) and GlcNAcβ1-4GlcNAcβ1-2Manα1-3Manβ1-4Glcβ1-1ceramide (IV⁴βGlcNAc-MlOse₄Cer, CPS) by compositional analysis, methylation analysis, exoglycosidase cleavage, gas-liquid chromatography, gas chromatograph-mass spectrometry and matrix-assisted laser desorption ionization time-of-flight mass spectrometry. Aliphatic constituents of CDS, CTS, CQS and CPS were virtually the same, with C16:0 and C18:0, and their 2-hydroxy homologues as the fatty acids, and octadecasphinga-4,8,10-trienine as the sole sphingoid. However, the ceramide compositions of CMS₁, CMS₂ and CMS₃ differed from those of the other four glycolipids. The fatty acid composition of CMS₁ consisted completely of C16:0, C17:0 and C18:0 acids, but both CMS₂ and CMS₃ contained instead of their 2-hydroxy homologues. The sphingoid components of CMS₁ and CMS₂ were octadecasphinga-4-enine and octadecasphinga-4,8,10-trienine, but that of CMS₃ was entirely trihydroxysphingoid, 4-hydroxyoctadecasphiganine.