Ceramides (Cer) and cerebrosides are important sphingolipids (SL) involved in many biological processes. Herein, the SL content of yellow lupin seeds (Lupinus luteus) was determined by liquid-liquid extraction, mild alkaline hydrolysis (1 h at 37 °C) and reversed-phase liquid chromatography with negative electrospray ionization coupled to either an orbital-trap (Fourier-transformed, FT) or linear ion-trap (LIT) mass spectrometry (RPLC-ESI/MS). The chemical identity of SL including the sugar residues and sphingoid backbone (SB) was inferred by collision-induced dissociation multiple-stage mass spectrometry (MSn, n = 2,3). Up to 52 Cer and 47 cerebrosides were successfully recognized and quantified in sample extracts of L. luteus seeds also counting isobaric species. As reported for other vegetables, a hydroxylated SB was observed whereby the N-acyl chains showed a high occurrence of very-long-chain moieties; phytosphingosine and 4-hydroxy-8-sphingenine were the predominant SB paired mainly with oleic acid (C18:1), hydroxylated behenic acid (C22:0;1) and hydroxylated lignoceric acid (C24:0;1).
Keywords: Ceramides; Cerebroside; Legume; Lupin; multistage CID-MS.
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