Characterization of lyso-galactolipids, C-2 and C-3 O-acyl trigalactosylglycerol isomers, obtained from the lichenized fungus Dictyonema glabratum

Abstract

A mixture of two lyso isomers of a galactolipid was obtained from Dictyonema glabratum. Aqueous hydrolysis gave rise to galactose and glycerol in a 3:1 molar ratio. ESI^MS spectroscopy gave, in the positive-ion mode, a pseudomolecular ion at m/z 839 and daughter ions with m/z 677, 600, 515 and 353, suggesting three galactosyl units linked to a glycerol moiety, substituted by one O-acyl group. 1D and 2D NMR experiments were used to characterize the glycolipid, and HMQC examination showed three anomeric signals, corresponding to two K-Galp and one L-Galp residue liked to glycerol. The glycolipid structure was shown to be-2-and -3-monoacyl-D-glycerol, the latter structures not having been previously found in nature. The fatty acid composition was determined by GC^MS of derived methyl esters: that of palmitic acid C 16:0 was the most abundant, although the presence of C 12:0 , C 14:0 , C 16:1 and C 18:0 esters was observed. ß

Positive and negative tandem mass spectrometric fingerprints of lipids from the halophilic Archaea Haloarcula marismortui

“…One of the most powerful is mass spectrometry (MS), in which tandem-MS configuration has been successfully employed to characterize the structures of several lipids, such as glycolipids, phosphonolipids, sphingolipids, and archaeal lipids (4,(12)(13)(14)(15)(16)(17)(18). Furthermore, recent improvements in the preparation of lipid derivatives allow the employment of gas liquid chromatography-mass spectrometry (GC-MS) for a broad range of analyses (19).…”