Model Studies on the Influence of High Hydrostatic Pressure on the Formation of Glycated Arginine Modifications at Elevated Temperatures

Abstract

Aqueous solutions of Nalpha-acetylarginine and glucose were reacted for 2 h with pressure application from 0 to 600 MPa and varying temperatures between 90 and 120 degrees C. After enzymatic deacetylation of the reaction products, the glycated amino acids were separated by means of a self-assembled preparative ion exchange chromatography system using ninhydrin detection. On the basis of the use of eight synthesized reference compounds known in the literature as posttranslational arginine modifications, first, the presence of several glycated amino acids could be excluded. On the other hand, N5-[[(1-carboxyethyl)amino]iminomethyl]ornithine [N7-(1-carboxyethyl)arginine; N7-CEA; 12] was identified as a previously unknown arginine modification based on LC-MS, NMR measurements, and synthesis. In addition, N5-(5-hydro-5-methyl-4-imidazolon-2-yl)-L-ornithine (1) was identified as a further major reaction product. In further experiments, the formation of 1 and 12 was quantitatively followed at different pressures and/or temperatures. The results indicated that high hydrostatic pressure at elevated temperatures significantly increased the amounts of both arginine modifications. 2-Oxopropanal, known to form 1 in a reaction with arginine, was also quantified to explain the different yields observed after pressure application. A new formation mechanism leading to 12 by a reaction of the guanidine group or arginine with 2-oxopropanal is discussed.

Tracking the behavior of Maillard browning in lysine/arginine–sugar model systems under high hydrostatic pressure

“…Moreover, reports on the effect of high pressure on arginine–sugar models are few. Notably, our results are consistent with those of Alt and Schieberle, who reported that high hydrostatic pressure at elevated temperatures significantly increased the amounts of certain arginine modification products.…”

“…Most fluorescent compounds produced in the Maillard reaction were reported to have typical excitation wavelengths of 340–370 nm and emission wavelengths of 420–470 nm, and the fluorescence results in the present work were within these ranges. As the Maillard reaction was reported to form extremely complex patterns of arginine modifications, the other peak detected at 400 nm may be attributed to the fluorescent compounds that formed with different structures . The fluorescent compounds with different emission wavelengths in the arginine–sugar models at 60 and 95 °C might indicate that temperature induced the production of intermediates via different pathways.…”

“…As the Maillard reaction was reported to form extremely complex patterns of arginine modifications, the other peak detected at 400 nm may be attributed to the fluorescent compounds that formed with different structures. 31 The fluorescent compounds with different emission wavelengths in the arginine-sugar models at 60 and 95 ∘ C might indicate that temperature induced the production of intermediates via different pathways. Temperature was reported to affect not only the overall reaction rate but also the relative rates and kinetics of different reaction pathways during the Maillard reaction.…”

Inhibition of L-Arginine Metabolizing Enzymes by L-Arginine-Derived Advanced Glycation End Products

“…CMA, CEA and MG-H1 were synthesized and purified according to the methods described previously [26]. Their structures were confirmed by nuclear magnetic resonance and electrospray ion mass spectrometry.…”

Pathways of the Maillard reaction under physiological conditions

“…Here, as illustrated in Fig. 5, the homologous structure N 7 -carboxyethyl arginine (CEA) [50,51] is a minor intermediate of the equilibrium between a kinetically controlled (MG-H3) and a thermodynamically controlled imidazolinone (MG-H1) [52]. In the methylglyoxal reactions the various cyclic imidazolinone and pyrimidine derivatives are Fig.…”