UTILITY OF NICOTINOYL DERIVATIVES IN STRUCTURAL STUDIES OF MONOACYLGLYCEROLS AND DIACYLGLYCEROLS BY GAS-CHROMATOGRAPHY MASS-SPECTROMETRY .3. APPLICATION TO ACYLGLYCEROLS WITH METHYL BRANCHINGS AND EPOXY AND CYCLOPROPYL RINGS

Mono- and diacylglycerols with methyl branches and epoxy and cycloprop yl rings were synthesized and, subsequently converted into their nicot inoyl derivatives by reaction with nicotinic acid and N,N'-dicyclohexy lcarbodiimide in the presence of N,N-dimethyl-4-aminopyridine. The res ulting nicotinoyl derivatives were examined by gas chromatography/mass spectrometry (GC/MS). Their electron impact mass spectra reveal the s tructures of mono- and diacylglycerols in greater detail than the mass spectra of other acylglycerol derivatives. The positions of methyl br anches and epoxy and cyclopropyl rings in mono- and diacylglycerols ca n be determined from characteristic features in the fragmentation patt erns, which are caused by radical-induced cleavage of the alkyl chains following random hydrogen abstraction by the pyridine nucleus, These results offer a promising approach to the structural analysis of glyce rophospholipids by means of GC/MS.