Assay of advanced glycation endproducts in selected beverages and food by liquid chromatography with tandem mass spectrometric detection

Food and beverages contain protein glycation adducts - both early-stage adducts and advanced glycation endproducts. We determined the concentrations of glycation adducts in selected food and beverages by liquid chromatography with triple quadrupole mass spectrometric detection. Cola drink contained low concentrations of glycation free adducts, whereas pasteurised and sterilised milk were rich sources of heat-stable glycation adduct residues - N-epsilon-carboxymethyl-lysine and N-epsilon-carboxyethyl-lysine. Laboratory rodent food was a rich source of advanced glycation endproducts. Measurement of glycation adducts in 24 h urine samples of normal and diabetic rats indicated that < 10% of glycation adduct residue consumption was excreted. Induction of diabetes by streptozotocin led to a 2-fold increase in urinary excretion of N-epsilon-carboxymethyl-lysine and a 27-fold increase in urinary excretion of methylglyoxal-derived hydroimidazolone N-delta-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine the latter was decreased by high-dose thiamine therapy that also prevented the development of nephropathy. We conclude that cola drinks are a poor source of glycation adduct whereas thermally processed milk is rich in glycation adducts. Dietary glycation adducts residues probably have low bioavailability. Experimental diabetes is associated with a marked increase in exposure to endogenous formation of methylglyoxal-derived hydroimidazolone which is linked to the development of diabetic nephropathy.