Abstract
Sphingolipids are composed of a ceramide backbone that consists of a C18 long-chain base (LCB) bound to a fatty acid via an amide linkage. Glucosylceramides (GlcCers) (also referred as 'cerebrosides' or 'glucocerebrosides' in plants) are a major class of complex sphingolipids that are formed by the addition of a glucose residue to a ceramide backbone. The LCBs in plant GlcCers are C-18 chain lengths and often include double bonds in C-4 or C-8 positions. Molecular species profiles of GlcCers that differentiate between Z and E stereoisomers of 8-unsaturated LCBs are not yet clear. In the present study, glucosylceramides molecular species were characterized by liquid chromatography tandem mass spectrometry in leaves of Poaceae. Liquid chromatography tandem mass spectrometry analysis was performed using a tandem quadrupole mass spectrometer (ACQUITY TQD, Waters). Molecular species including 2-hydroxy arachidic acids paired with 4-E, 8-Z-sphingadienine and 4-E, 8-E-sphingadienine were found. In addition, 4-hydroxy-8-Z-sphingenine and 4-hydroxy-8-E-sphingenine [t18:1(8Z) and t18:1(8E)] were exclusively attached to 2-hydroxy fatty acids (2-hFAs) with 22 to 26 carbon chain lengths.
