Quantitation of free glycation compounds in saliva

Abstract

In the course of the Maillard reaction, which occurs during heating of food but also under physiological condition, a broad spectrum of reaction products is formed. Among them, the advanced glycation endproducts (AGEs) Nε-carboxymethyllysine (CML), pyrraline (Pyr), methylglyoxal-derived hydroimidazolone 1 (MG-H1) and Nε-carboxyethyllysine (CEL) are the quantitatively dominating compounds during later reaction stages. Those dietary glycation compounds are under discussion as to be associated with chronic inflammation and the pathophysiological consequences of diseases such as diabetes. In the present study, the concentration of individual glycation compounds in saliva was monitored for the first time and related to their dietary uptake. Fasting saliva of 33 metabolically healthy subjects was analyzed with HPLC-MS/MS. The observed levels of individual glycation compounds ranged from 0.5 to 55.2 ng/ml and differed both intra- and interindividually. Patterns did not correlate with subject-related features such as vegetarianism or sports activities, indicating that dietary intake may play an important role. Therefore, six volunteers were asked to eat a raw food diet free of glycation compounds for two days. Within two days, salivary Pyr was lowered from median 1.7 ng/ml to a minimum level below the limit of detection, and MG-H1 decreased from 3.6 to 1.7 ng/ml in in a time-dependent manner after two days. Salivary CML and CEL concentrations were not affected. Therefore, measuring Pyr and MG-H1 in saliva is a suitable diagnostic tool to monitor the dietary intake and metabolic transit of glycation compounds present in heated foods.

Effects of Exogenous Dietary Advanced Glycation End Products on the Cross-Talk Mechanisms Linking Microbiota to Metabolic Inflammation

“…These results imply that AGEs found in salivary glands originate, at least in part, from blood. This hypothesis has been recently confirmed in an intervention study on healthy subjects exposed to diets with different amount and quality of AGEs [13]. Nevertheless, the specific mechanisms of transports of AGEs from blood to saliva remains to be elucidated.…”

“…The fraction of arginine and lysine that had been modified was replaced in the diet by the addition of the respective amounts of free lysine and arginine, so that any effect elicited by the diet may not be due to a deficiency in these essential amino acids. This preparation contained 17.4 ± 1.5 g/kg MG-H1 as analyzed by HPLC-MS/MS after enzymatic hydrolysis [13].…”

Fructose and methylglyoxal-induced glycation alters structural and functional properties of salivary proteins, albumin and lysozyme

“…It is known that MGO forms hydroimidazolone derived from modification of arginine (MG-H1) and also carboxyethylisine (CEL) [53]. Manig et al [77] suggested that levels of glycation compounds in saliva may be useful biomarkers to assess diabetes, since some AGEs found in saliva, such as CEL, CML and MG-H1, are higher in diabetic individuals. Studies involving the formation of AGEs in a hyperglycemic state have shown that MGO is considered the main precursor to AGEs, which can lead to enzymatic inactivation and protein denaturation [7,78].…”

Influence of 3-DG as a Key Precursor Compound on Aging of Lager Beers

“…For example, pyrraline is formed from lysine (Lys) during reaction with 3-DG . Further, Lys reacts with MGO to N ε -carboxyethyllysine (CEL) , and with GO to N ε -carboxymethyllysine (CML). , In addition to Lys, arginine (Arg) is also prone to be modified in the late Maillard reaction and forms the methylglyoxal-derived hydroimidazolone 1 (MG-H1) with MGO Figure shows the above-mentioned metabolites.…”

“…18,20 In addition to Lys, arginine (Arg) is also prone to be modified in the late Maillard reaction and forms the methylglyoxal-derived hydroimidazolone 1 (MG-H1) with MGO. 18 Figure 1 shows the above-mentioned metabolites.…”