Amount Of Carboxymethyl)lysine Research Articles

Inhibitory effect of naringenin on Nε‐(carboxymethyl) lysine during cooking of meatballs

SummaryThe aim of this study was to determine the effect of naringenin (Ngn) on Nε‐(carboxymethyl)lysine (CML) inhibition during the cooking of meatballs. In addition, to determine the relationship of CML formation in meatballs with TBARS and pH. For this purpose, CML, TBARS, pH, and sensory analyses were performed by cooking the meatballs in which Ngn was added at different rates and storing them at 4 ± 1 °C for 16 days, by cooking them at 250 °C for 10 min at intervals of 4 days. The amount of CML in the meatballs was 13.74 ± 0.73–14.29 ± 0.56 on day 0 and between 15.24 ± 0.12 and 18.15 ± 0.43 μg g−1 on day 16. TBARS values of the meatballs were between 1.55 ± 0.21 and 1.78 ± 0.17 on day 0 and between 2.54 ± 0.28 and 3.28 ± 0.47 mg MDA kg−1 on day 16. It was determined that there was a difference between the groups containing Ngn and the control group in terms of smell and general taste on the 8th storage day and in the general taste on the 12th storage day. As a result, it was determined that the addition of naringenin to the meatball composition inhibited the formation of CML in the meatballs, slowed the oxidation rate, and did not adversely affect the sensory properties. Thus, it can be emphasised that adding naringenin to meatballs will add functional properties to meatballs and turn them into a more beneficial product for human health. This research provides valuable references and guidelines for the safety of fried foods based on the control of advanced glycation end products (AGEs).

Development of Evaluation Methods for Anti-Glycation Activity and Functional Ingredients Contained in Coriander and Fennel Seeds

Spices are known to have various physiological functions. We focused on the anti-glycation effects of spices, researched anti-glycation active ingredients in coriander (Coriandrum sativum L.) and fennel (Foeniculum vulgare) seeds, and conducted experiments using human skin-derived fibroblast TIG-110 cells as a model of glycation. We isolated 11 compounds from two spice seeds and found several substances that showed anti-glycation activity. A new compound (5,5′-diallyl-2,2′-diglucopyranosyl-3,3′-dimethoxy diphenyl ether) was isolated from fennel seeds and showed high anti-glycation activity with an IC50 value of 0.08 mM, thereby indicating a high anti-glycosylation activity. In this study, we established a glyoxal (GO)-induced glycation test method for human skin cells, confirmed the anti-glycation effect of spice seeds using this glycation induction model, and found that the exposure of TIG-110 human skin-derived fibroblast cells to GO reduced cell viability. The most stable conditions for cell viability were found to be a GO concentration of 1.25 mM and a culture time of 48 h. We evaluated extracts and isolates of spice seeds using this model as a model test for glycation induction. We conducted qualitative and quantitative analyses of carboxymethyl lysine (CML), a type of AGE, to determine the relationship between cell viability and AGEs. The relationship between cell viability and the amount of CML was correlated. Establishing a glycation induction model test using skin cells makes it possible to quickly screen extracts of natural ingredients in the future. Moreover, the results of this model showed that extracts of two spice seeds and their isolates have high anti-glycation activity, and they are expected to be used as cosmetics, health foods, and pharmaceutical ingredients.

Amino acid profile and Maillard compounds of sun-dried pears. Relation with the reddish brown colour of the dried fruits

The sun-dried pear of S. Bartolomeu (Pyrus communis L. var. S. Bartolomeu) is a traditional sweet food product of unique elastic properties and reddish brown colour. Alternative drying methodologies to replace the traditional open air sun-drying procedure are under development, namely the use of greenhouses with and without air convection and a hot air tunnel. To test whether the Maillard reactions can contribute to the colour of this traditional product, the profiles of free and bound amino acids constituents of the pulp of fresh pears as well as pears processed according to different drying methodologies were evaluated. Also, the occurrence of furosine, carboxymethyllysine (CML) and carboxyethyllysine (CEL), indicative of Maillard reaction, was diagnosed and quantified. The drying of the pears affects the free amino acid profile, increasing proline content and decreasing aspartic and glutamic acids. Although the proteic amino acid profile was not significantly modified with the drying process, a loss of the relative content of Lys was observed. This loss was related with the increase in the amount of furosine, CML and CEL formed during the drying of the fruits. Although all drying methods tested promoted the increase in the amount of CML, CEL and furosine, this increase was higher in the case of the traditional sun-drying and greenhouse processing, where the fruits presented reddish brown colour, and lower for the hot air tunnel processing, where the fruits became less intense. These results allow affirming that the drying process promotes the occurrence of Maillard reaction, contributing to the characteristic reddish brown colour of the final product.

Oxidative Damage in the Liver of Rats Treated With Glycolaldehyde

Liver diseases are often associated with hyperglycemia, inflammation, and oxidative stress. These conditions, commonly associated with diabetes mellitus and obesity, facilitate the formation of advanced glycation end products (AGEs). These products are known to impair protein function and promote inflammation. Accumulation of AGEs such as N(ε)-(carboxymethyl)lysine (CML) is related to chronic liver diseases and their severity. Although several reports suggest a crucial role of AGEs in liver failure, there is little investigation on the direct effects of reducing sugars, precursors of AGEs, and on the onset and progression of liver failure. In this work, we investigate the effects of intravenously administrated glycolaldehyde (GA), a short-chain aldehyde, on oxidative parameters in the liver of Wistar rats. Animals received a single injection of GA (10, 50, or 100 mg/kg) and were sacrificed after 6, 12, or 24 hours. Levels of protein carbonyl, lipid peroxidation, and reduced thiol were quantified. The activities of catalase, superoxide dismutase, and glyoxalase I were also assessed. The amount of CML was quantified with specific antibody. There was an increase in oxidative stress markers in the liver of GA-treated rats. Glycolaldehyde induced a decrease in the activities of all enzymes assayed. Also, all tested doses led to an increase in CML content. Our data suggest that GA might play an important role in liver diseases through the impairment of antioxidant defenses and generation of AGEs.

Antiglycation Effects of Carnosine and Other Compounds on the Long-Term Survival of Escherichia coli

Glycation, or nonenzymatic glycosylation, is a chemical reaction between reactive carbonyl-containing compounds and biomolecules containing free amino groups. Carbonyl-containing compounds include reducing sugars such as glucose or fructose, carbohydrate-derived compounds such as methylglyoxal and glyoxal, and nonsugars such as polyunsaturated fatty acids. The latter group includes molecules such as proteins, DNA, and amino lipids. Glycation-induced damage to these biomolecules has been shown to be a contributing factor in human disorders such as Alzheimer's disease, atherosclerosis, and cataracts and in diabetic complications. Glycation also affects Escherichia coli under standard laboratory conditions, leading to a decline in bacterial population density and long-term survival. Here we have shown that as E. coli aged in batch culture, the amount of carboxymethyl lysine, an advanced glycation end product, accumulated over time and that this accumulation was affected by the addition of glucose to the culture medium. The addition of excess glucose or methylglyoxal to the culture medium resulted in a dose-dependent loss of cell viability. We have also demonstrated that glyoxylase enzyme GloA plays a role in cell survival during glycation stress. In addition, we have provided evidence that carnosine, folic acid, and aminoguanidine inhibit glycation in prokaryotes. These agents may also prove to be beneficial to eukaryotes since the chemical processes of glycation are similar in these two domains of life.

Formation pathways of Nε-(carboxymethyl)lysine and dicarbonyl compounds by peroxynitrite

In our previous paper, hydroxyl radical was found to be a major reactive oxygen species for Nε-(carboxymethyl)lysine (CML) formation through Amadori products. Peroxynitrite (PN) is also known as one of the reactive oxygen species. However, the contribution of PN to the formation of advanced glycation end products (AGE) such as CML has been poorly understood so far. In this work, the effect of PN on CML formation was discussed. First, glycated human serum albumin (glycated HSA) was incubated with 70 μM PN at 37 °C for 1 h. Second, d-glucose was incubated with 1 mM PN at 37 °C for 30 min in advance, followed by further incubation in the presence of HSA at 37 °C for 24 h. The amount of CML in these samples was determined by ELISA. After incubation of glycated HSA with PN for 5 min, CML formation was observed to a significant extent. Furthermore, the reaction of PN-treated glucose with HSA resulted in the production of CML. In contrast, CML was not formed in the parallel incubation without PN. To determine aldehydes produced during PN-induced CML formation, aliquots of the reaction mixtures were mixed with 2,3-diaminonaphthalene (DAN) and then quantified by HPLC. This experiment demonstrated that glucosone is an important intermediate on the formation of CML.

Advanced glycation end products in Descemet’s membrane and their effect on corneal endothelial cell

Purpose. The purpose of this study was to evaluate the effect of advanced glycation end products (AGEs) in Descemet’s membrane on the attachment and spreading of the corneal endothelial cells. Methods. An anti-AGEs monoclonal antibody (6D12), which recognizes a N e -carboxymethyl lysine (CML)-protein adduct as an epitope, was used for immunohistochemistry and enzyme-linked immunosorbent assay (ELISA). Fresh bovine Descemet’s membrane was incubated for 4 weeks in the buffered solution with 500 mM of glucose-6-phosphate (G-6-P). In the incubated Descemet’s membrane, the immunohistochemical localization of CML was examined. Type I collagen-, type IV collagen-, fibronectin-, or laminin-coated 96-well plates were glycated by G-6-P. The amount of CML was determined by ELISA using 6D12. Cultured bovine corneal endothelial cells were seeded onto glycated or non-glycated extracellular matrix (ECM) in 96-well plates and allowed to attach for 3 hours. The number and the surface area of the attached cells were examined. Results. Immunoreactivity to CML was detected in Descemet’s membrane incubated in the buffered solution containing G-6-P. Glycation of fibronectin and laminin decreased the number and the surface area of the attached corneal endothelial cells. Aminoguanidine in the incubation mixture inhibited CML formation of ECM components and increased the number and the surface area of the attached corneal endothelial cells in a dose-dependent manner. Conclusions. AGE formation on fibronectin and laminin attenuated the attachment and spreading of the corneal endothelial cells. AGEs’ formation in Descemet’s membrane may be responsible for the corneal endothelial cell loss with aging and corneal endothelial abnormalities in diabetic patients