- Simultaneous generation of acrylamide, β-carboline heterocyclic amines and advanced glycation ends products in an aqueous Maillard reaction model system
-
The simultaneous formation of acrylamide; β-carboline heterocyclic amines (HAs): harmane and norharmane; and advanced glycation end products (AGEs) (Nε-(carboxymethyl)lysine (CML) and Nε-(carboxyethyl)lysine (CEL)) was analyzed based on an aqueous model system. The model systems included lysine–glucose (Lys/Glu), asparagine–glucose (Asn/Glu), tryptophan–glucose (Trp/Glu), and a mixture of these amino acids (Mix/Glu). Only AGEs were generated when heated at 100 °C, Asn and Trp competed with Lys for glucose and methylglyoxal (MGO), and glyoxal (GO) decreased AGE content. The k value of CML, CEL, and acrylamide decreased when heated at 130 °C, whereas that of harmane increased in the Mix/Glu, owing to the competition between Lys and Asn for glucose, GO, and MGO. Harmane preferably formed via the Pictet–Spengler condensation between Trp and acetaldehyde, which further reduced acrylamide formation via the acrolein pathway.
- Chen, Jie,He, Zhiyong,Jiao, Ye,Li, Yong,Liu, Guoping,Qin, Fang,Quan, Wei,Wang, Zhaojun,Xue, Chaoyi,Zeng, Maomao
-
-
- The neurotoxicity of Nε-(carboxymethyl)lysine in food processing by a study based on animal and organotypic cell culture
-
Nε-(carboxymethyl)lysine (CML) is a potentially noxious compound that is causing widespread concern due to its use in various food products. In this study, we investigated CML neurotoxicity via an in vivo experiment with mice, and an in vitro experiment using a 3D microvascular network model (with human brain vascular endothelial cell and human astrocyte) that simulated the blood-brain barrier. We found that CML could induce cell survival status variations, and histopathological changes to the brain. In addition, CML increased levels of oxidative stress, prompted the protein expression of the receptor for advanced glycation end-products (RAGE). CML up-regulated both the gene expression of RAGE, the activating protein-1 (AP-1), the inflammatory cytokines Interleukin-6 (IL-6), vascular cell adhesion molecule1 (VCAM-1), monocyte chemotactic protein1 (MCP-1). We, therefore, postulated that CML has the potential to deleteriously affect the nervous system through oxidative stress and that activation of the p38 MAPK-AP-1 signaling pathway might be implicated in this pathological process.
- Gong, ZhiYong,Li, Yan,Wang, Pengcheng,Wu, Yang,Wu, Yongning,Zheng, Liangqing,liu, Yan
-
-
- Glucoselysine is derived from fructose and accumulates in the eye lens of diabetic rats
-
Prolonged hyperglycemia generates advanced glycation endproducts (AGEs), which are believed to be involved in the pathogenesis of diabetic complications. In the present study, we developed a polyclonal antibody against fructose-modified proteins (Fru-P antibody) and identified its epitope as glucoselysine (GL) by NMR and LC-electrospray ionization (ESI)- quadrupole TOF (QTOF) analyses and evaluated its potential role in diabetes sequelae. Although the molecular weight of GL was identical to that of fructoselysine (FL), GL was distinguishable from FL because GL was resistant to acid hydrolysis, which converted all of the FLs to furosine. We also detected GL in vitro when reduced BSA was incubated with fructose for 1 day. However, when we incubated reduced BSA with glucose, galactose, or mannose for 14 days, we did not detect GL, suggesting that GL is dominantly generated from fructose. LC-ESI-MS/MS experiments with synthesized [13C6]GL indicated that the GL levels in the rat eye lens time-dependently increase after streptozotocininduced diabetes. We observed a 31.3-fold increase in GL 8 weeks after the induction compared with nondiabetic rats, and N∈-(carboxymethyl)lysine and furosine increased by 1.7- and 21.5-fold, respectively, under the same condition. In contrast, sorbitol in the lens levelled off at 2 weeks after diabetes induction. We conclude that GL may be a useful biological marker to monitor and elucidate the mechanism of protein degeneration during progression of diabetes.
- Ohno, Rei-Ichi,Ichimaru, Kenta,Tanaka, Seitaro,Sugawa, Hikari,Katsuta, Nana,Sakake, Shiori,Tominaga, Yu-Ki,Ban, Ikuho,Shirakawa, Jun-Ichi,Yamaguchi, Yoshiki,Ito, Emi,Taniguchi, Naoyuki,Nagai, Ryoji
-
p. 17326 - 17338
(2019/11/25)
-
- Novel α-Oxoamide Advanced-Glycation Endproducts within the N6-Carboxymethyl Lysine and N6-Carboxyethyl Lysine Reaction Cascades
-
The highly reactive α-dicarbonyl compounds glyoxal and methylglyoxal are major precursors of posttranslational protein modifications in vivo. Model incubations of N2-t-Boc-lysine and either glyoxal or methylglyoxal were used to further elucidate the underlying mechanisms of the N6-carboxymethyl lysine and N6-carboxyethyl lysine reaction cascades. After independent synthesis of the authentic reference standards, we were able to detect N6-glyoxylyl lysine and N6-pyruvoyl lysine for the first time by HPLC-MS2 analyses. These two novel amide advanced-glycation endproducts were exclusively formed under aerated conditions, suggesting that they were potent markers for oxidative stress. Analogous to the well-known Strecker degradation pathway, leading from amino acids to Strecker acids, the oxidation of an enaminol intermediate is suggested to be the key mechanistic step. A highly sensitive workup for the determination of AGEs in tissues was developed. In support of our hypothesis, the levels of N6-glyoxylyl lysine and N6-pyruvoyl lysine in rat livers indeed correlated with liver cirrhosis and aging.
- Baldensperger, Tim,Jost, Tobias,Zipprich, Alexander,Glomb, Marcus A.
-
p. 1898 - 1906
(2018/03/06)
-
- A kind of organic synthesis of carboxymethyl lysine separation and purification method
-
The invention provides a separating purification method of organically synthesized carboxy methyl lysine. Separating purification is a key step for finally obtaining high-purity carboxy methyl lysine; preparative liquid chromatography and ion exchange chromatography separating purification methods are used at present in the prior art and these methods are relatively cumbersome, low in efficiency and not suitable for mass preparation. To explore quick, efficient and low-price separating purification method becomes very important for obtaining a large quantity of low-cost high-purity carboxy methyl lysine monomers. The separating purification method of carboxy methyl lysine is innovated boldly in the invention, the synthesis amount of carboxy methyl lysine is improved to the gram grade, the purification efficiency of carboxy methyl lysine is increased greatly, the experiment cost is lowered, and a foundation is further laid for carrying out various toxicological evaluations on carboxy methyl lysine.
- -
-
Paragraph 0056; 0072-0073
(2020/05/05)
-
- Convenient synthesis of Nε-(carboxymethyl)lysine, a key advanced glycation endproduct biomarker
-
Advanced glycation endproducts (AGEs) are formed when sugars react with peptides and proteins without the help of enzymes and by thermal processing of food such as baking and frying. AGEs and especially N-(carboxymethyl) lysine (CML) has been used as general key biomarkers for oxidative stress and a number of diseases associated with poor lifestyle. Herein we present the first synthetic pathway to the free zwitter ion of CML via a protected intermediate. Georg Thieme Verlag Stuttgart · New York.
- Andersen, Jeanette M.,Hjelmgaard, Thomas,Dragsted, Lars O.,Nielsen, John
-
experimental part
p. 531 - 534
(2012/04/04)
-
- Astragalosides isolated from the root of astragalus radix inhibit the formation of advanced glycation end products
-
Because advanced glycation end product (AGE) inhibitors such as pyridoxamine significantly inhibit the development of retinopathy and neuropathy in the streptozotocin-induced diabetic rat, treatment with AGE inhibitors is believed to be a potential strate
- Motomura, Keita,Fujiwara, Yukio,Kiyota, Naoko,Tsurushima, Keiichiro,Takeya, Motohiro,Nohara, Toshihiro,Nagai, Ryoji,Ikeda, Tsuyoshi
-
experimental part
p. 7666 - 7672
(2010/09/15)
-
- Identification of the carboxymethyllysine residue in the advanced stage of glycated human serum albumin
-
As an advanced stage of glycation, glycated human serum albumin (G-HSA; glucose content, 2 mol of 5-hydroxymethylfurfural equivalent/mol of HSA) was incubated at 37°C up to 30 d in 0.2 M phosphate buffer, pH 7.4, with 100 μM Fe3+. G-HSA incubated for 30 d (G-HSA-30(Fe)) was subsequently hydrolyzed at 110 °C for 24 h in 6 N HCl. In the hydrolysate, N(ε)-carboxymethyllysine (CML) was identified by cochromatography with synthesized CML on an amino acid analyzer. pI of HSA (4.8) shifted to 4.5 in G-HSA. A more acidic fraction, pI 4.3, appeared in G-HSA-30(Fe). CML content (mol of CML/mol of HSA) of HSA and G-HSA was as follows; 0 in HSA, 0.2 in HSA-30(Fe), 0.4 in G-HSA and 1.5 in G-HSA-30(Fe) pI 4.3. The amino acid compositions also changed in lysine, arginine and tyrosine at the advanced stage of the reaction.
- Takanashi,Sakurai,Tsuchiya
-
p. 705 - 708
(2007/10/02)
-