Ion-trap tandem mass spectrometric analysis of amadori-glycated phosphatidylethanolamine in human plasma with or without diabetes

Peroxidized phospholipid-mediated cytotoxicity is involved in the pathophysiology of diseases (i.e., an abnor- mal increase of phosphatidylcholine hydroperoxide (PCOOH) in plasma of type 2 diabetic patients). The PCOOH accu- mulation may relate to Amadori-glycated phosphatidyletha- nolamine (Amadori-PE; deoxy- d -fructosyl phosphatidyleth- anolamine), because Amadori-PE causes oxidative stress. However, the occurrence of lipid glycation products, includ- ing Amadori-PE, in vivo is still unclear. Consequently, we de- veloped an analysis method of Amadori-PE using a qua- drupole/linear ion-trap mass spectrometer, the Applied Biosystems QTRAP. In positive ion mode, collision-induced dissociation of Amadori-PE produced a well-characterized diglyceride ion ((MH � 303) � ) permitting neutral loss scan- ning and multiple reaction monitoring (MRM). When lipid extract from diabetic plasma was infused directly into the QTRAP, Amadori-PE molecular species could be screened out by neutral loss scanning. Interfacing liquid chromatog- raphy with QTRAP mass spectrometry enabled the separa- tion and determination of predominant plasma Amadori-PE species with sensitivity of � 0.1 pmol/injection in MRM. The plasma Amadori-PE level was 0.08 mol% of total PE in healthy subjects and 0.15-0.29 mol% in diabetic patients. Furthermore, plasma Amadori-PE levels were positively cor- related with PCOOH (a maker for oxidative stress). These results show the involvement between lipid glycation and lipid peroxidation in diabetes pathogenesis. —Nakagawa, K., J-H. Oak, O. Higuchi, T. Tsuzuki, S. Oikawa, H. Otani, M. Mune, H. Cai, and T. Miyazawa. Ion-trap tandem mass spectrometric analysis of Amadori-glycated phosphatidyl- ethanolamine in human plasma with or without diabetes. J. Lipid Res. 2005. 46: 2514-2524.