fructosyl-lysine and furosine

OBJECTIVE Salsalate is a nonacetylated salicylate that lowers glucose levels in people with type 2 diabetes (T2D). Here we examined whether salsalate also lowered serum-protein-bound levels of early and advanced glycation end products (AGEs) that have been implicated in diabetic vascular complications. RESEARCH DESIGN AND METHODS Participants were from the Targeting Inflammation Using Salsalate for Type 2 Diabetes (TINSAL-T2D) study, which examined the impact of salsalate treatment on hemoglobin A1c (HbA1c) and a wide variety of other parameters. One hundred eighteen participants received salsalate, 3.5 g/day for 48 weeks, and 109 received placebo. Early glycation product levels (HbA1c and fructoselysine [measured as furosine]) and AGE levels (glyoxal and methylglyoxal hydroimidazolones [G-(1)H, MG-(1)H], carboxymethyllysine [CML], carboxyethyllysine [CEL], pentosidine) were measured in patient serum samples. RESULTS Forty-eight weeks of salsalate treatment lowered levels of HbA1c and serum furosine (P < 0.001) and CML compared with placebo. The AGEs CEL and G-(1)H and MG-(1)H levels were unchanged, whereas pentosidine levels increased more than twofold (P < 0.001). Among salsalate users, increases in adiponectin levels were associated with lower HbA1c levels during follow-up (P < 0.001). Changes in renal and inflammation factor levels were not associated with changes in levels of early or late glycation factors. Pentosidine level changes were unrelated to changes in levels of renal function, inflammation, or cytokines. CONCLUSIONS Salsalate therapy was associated with a reduction in early but not late glycation end products. There was a paradoxical increase in serum pentosidine levels suggestive of an increase in oxidative stress or decreased clearance of pentosidine precursor.

Topics: Adiponectin; Adult; Anti-Inflammatory Agents, Non-Steroidal; Arginine; Diabetes Mellitus, Type 2; Diabetic Angiopathies; Female; Glycated Hemoglobin; Glycation End Products, Advanced; Humans; Lysine; Male; Middle Aged; Pyruvaldehyde; Salicylates

Furosine, generated by acid hydrolysis of fructosyllysine, an early Maillard reaction product, is a highly valuable indicator of food quality and, more specifically, of food protein quality. Ion pair RP-HPLC and CZE techniques were employed to determine furosine content in beverages based on soymilk (n = 15) and cow's milk supplemented with soy isoflavones (n = 1). The levels of furosine found in the samples ranged from 25.55 +/- 0.18 to 170.72 +/- 10.4 mg/100 g of protein by HPLC and from 28.67 +/- 1.84 to 161.25 +/- 5.78 mg/100 g of protein by CZE. Results obtained by both analytical techniques do not differ significantly (p > 0.05), confirming their feasibility for furosine analysis in soy-based products.

Topics: Chromatography, High Pressure Liquid; Electrophoresis, Capillary; Food Analysis; Hydrogen-Ion Concentration; Lysine; Molecular Structure; Soy Milk; Soybean Proteins

In several studies, the absorption and urinary excretion of free and protein bound Amadori products were measured in rats and humans. Both, in vitro tests with everted intestinal sac preparations and in vivo experiments, showed that there is no active intestinal transport of these compounds but an absorption by diffusion. Trials with tissue slices have shown that there was an uptake into the cells of the liver, kidneys and muscles. Metabolism of Amadori products, if it exists in animals, tends to be very low. Micoorganisms in the large intestines decompose the Amadori products almost completely. The profile of urinary excretion of Amadori products after the ingestion of test meals showed a rapid elimination of the absorbed part, while the fecal output, although low because of the hind gut fermentation, persisted up to 3 days. Only 1-3% of the ingested amounts of protein bound Amadori products were recovered in the urine, which suggests a low absorption rate.

Topics: Adult; Amino Acids; Animals; Carbon Isotopes; Chromatography, Ion Exchange; Culture Techniques; Diffusion; Feces; Female; Gastrointestinal Transit; Humans; Intestinal Absorption; Kinetics; Lysine; Maillard Reaction; Male; Rats

By analyzing lysine and furosine the amount of inactivated lysine in several food systems was determined and the values for available lysine and total lysine were calculated. Considerable heat damage was found in heated cereal products, and in heated milk products, including several formula for children and hospitalized patients. Some products contained more inactivated lysine than available lysine. This may have consequences for the nutrition in low protein consuming populations and leads to errors in predicting the protein quality, e.g., by the recently proposed "Protein Digestibility Corrected Amino Acid Score".

Topics: Biological Availability; Dietary Proteins; Food Analysis; Food Handling; Hot Temperature; Humans; Lysine; Maillard Reaction; Nutritive Value

Furosine, which was formed by acid hydrolysis of fructose-lysine, was determined and used as an indicator of glycosylated protein. The diabetic patients had significantly higher fructose-lysine levels in finger nails than healthy subjects [10.8 +/- 4.6% (mean +/- S.D.) vs 4.2 +/- 1.1%]. The best correlation was found between the fructose-lysine value and the fasting blood glucose level determined 3 to 5 months before sampling nails in diabetics. These results suggest that the furosine derived from fructose-lysine in finger nails may become an indicator of blood glucose control during the past 3 to 5 months in diabetics.

Topics: Adult; Aged; Aged, 80 and over; Blood Glucose; Diabetes Mellitus, Type 2; Female; Humans; Lysine; Male; Middle Aged; Nails

Fructose-lysine, which is formed by binding glucose to lysine, is changed by acid hydrolysis into furosine. Furosine derived from fructose-lysine of hair was determined by high-performance liquid chromatography according to the method of Schleicher et al. Furosine values were significantly higher in diabetic patients than in healthy subjects, and significantly correlated with the stable components of hemoglobin A1 (HbA1) values. These results suggest that furosine, like HbA1, may become an indicator of past blood glucose control at any time in diabetic patients and be useful in investigating diabetic complications on the level of tissue.

Topics: Adult; Aged; Chromatography, High Pressure Liquid; Diabetes Mellitus, Type 2; Female; Glycated Hemoglobin; Hair; Humans; Lysine; Male; Middle Aged; Proteins