Distinguishing native trisaccharides having differential monosaccharide composition and linkage using PGC-LC MS/MS

Native glycosyl sucrose derivatives in plants represents primarily the trisaccharide isomers having different monosaccharides composition and linkage specificity. They can occur as complex mixtures wherein the separation and identification of individual trisaccharide becomes challenging. Herein, we employed porous graphitic carbon (PGC) liquid chromatography coupled to mass spectrometry to evaluate the elution order of major glycosyl sucrose trisaccharides and determined the structural feature through tandem mass spectrometry (MS/MS). Major trisaccharides comprised of galactosyl-, glucosyl- and fructosyl sucrose derivatives along with few reducing trisaccharides revealed distinct elution order. Furthermore, the application of this approach to profile the oligosaccharides in grape seeds showed the separation and identification of multiple native trisaccharides in the complex mixture that were hitherto unknown.