New Imidazoles Formed in Nonenzymatic Browning Reactions

Velı́šek, J.; Davídek, Tomáš; Davíek, J.; Trška, Petr; Kvasnička, František; Velcová, K.

doi:10.1111/j.1365-2621.1989.tb05155.x

Cited by 34 publications

(19 citation statements)

References 16 publications

(9 reference statements)

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“…[16,17] However, 1 can also be readily synthesised from the reaction of N-(trimethylsilyl)imidazole with two equivalents of methyl chloroacetate, followed by ester hydrolysis and neutralisation of one carboxylic acid group with an organic Abstract: A series of imidazolium dicarboxylic acids have been prepared from the reaction of the 1,3-bis(carboxyA C H T U N G T R E N N U N G methyl)imidazolium zwitterion with the Brønsted acids HX (X = F, Br, Cl, ClO 4 ). The structures of these acids have been established in the solid state by single-crystal X-ray diffraction, which revealed that the cations and anions form strong hydrogen bonds through OÀH···X interactions, leading to the formation of dimeric and polymeric networks.…”

Section: Resultsmentioning

confidence: 99%

Ionic Solid‐State Dimers and Polymers Derived from Imidazolium Dicarboxylic Acids

Fei

Ang

Geldbach

et al. 2006

Chemistry A European J

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A series of imidazolium dicarboxylic acids have been prepared from the reaction of the 1,3-bis(carboxymethyl)imidazolium zwitterion with the Brønsted acids HX (X = F, Br, Cl, ClO4). The structures of these acids have been established in the solid state by single-crystal X-ray diffraction, which revealed that the cations and anions form strong hydrogen bonds through O-H...X interactions, leading to the formation of dimeric and polymeric networks. These acids react with elemental zinc and cobalt to form stable polymeric coordination complexes, some of which have also been characterised by X-ray diffraction.

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Section: Resultsmentioning

confidence: 99%

Ionic Solid‐State Dimers and Polymers Derived from Imidazolium Dicarboxylic Acids

Fei

Ang

Geldbach

et al. 2006

Chemistry A European J

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“…Compounds similar to imidazolysine have been isolated by food chemists from the reaction of glycine or glycyl glycine with glyoxal in the presence of formaldehyde at high temperature (31,32). However, imidazolysine was isolated from the reaction mixture obtained under physiological conditions, and its mechanism of formation does not seem to involve the participation of formaldehyde.…”

Section: Discussionmentioning

confidence: 99%

Protein Cross-linking by the Maillard Reaction

Nagaraj

Shipanova

Faust

1996

Journal of Biological Chemistry

282

101

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The Maillard reaction, initiated by the nonenzymatic reaction of reducing sugars with proteins, is proposed to play a significant role in protein aging and the complications of aging and diabetes. The reaction is initiated with the reversible formation of a Schiff base between a reducing sugar and the amino group of a protein. The relatively unstable Schiff base undergoes rearrangement to form a more stable Amadori product. The Amadori product, over a period of several months to years, undergoes a series of further reactions through dicarbonyl intermediates to form advanced glycation end products (AGEs) 1 that are also known as advanced Maillard products. The AGEs are a heterogeneous group of structures formed as both cross-linking and noncross-linking adducts on proteins. The long-lived proteins in the body like lens crystallins and collagen accumulate AGEs because of their negligible or slow turnover. Immunochemical and chemical methods have clearly shown the progressive accumulation of AGEs in tissue proteins in aging (1-3). In diabetes, AGE accumulation in general is accelerated and linked to atherosclerosis, nephropathy, neuropathy, retinopathy, and cataract (4 -8). The binding of AGEs to specific receptors on macrophages has been shown to result in the synthesis of cytokines and growth factors and enhanced oxidative stress (9 -12). These events are proposed to play a major role in age-and diabetes-associated vascular complications.Considerable interest has focused recently on the structural characterization of AGEs. Attempts are being made to isolate major products by using specific antibodies and by chromatographic methods. A consistent difficulty in these procedures has been the isolation of individual AGEs in a reaction where numerous products are formed with highly cross-linked structures. Although protein cross-linking is a major end result of the Maillard reaction, only two minor protein cross-linking compounds, pentosidine and fluorophore LM-1, have been detected in tissues (13)(14)(15). Therefore, to better understand the impact of the Maillard reaction in aging and diabetes and to develop effective therapeutic methods to prevent AGE accumulation in tissues, it is necessary to elucidate the chemical nature of the major protein cross-links derived from this reaction.In addition to glucose, a number of other sugars and sugar metabolites are known to initiate the Maillard reaction. Among them methylglyoxal (MG) has attracted considerable attention recently. MG is formed by enzymatic and nonenzymatic routes from glycolytic intermediates as well as from autoxidation of sugars (16,17). It has been shown that in diabetes the concentration of MG increases in the lens, blood, and kidney (18 -20). In Type I diabetic patients the blood MG levels increased 5-6-fold and in Type II 2-3-fold compared with normal control

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“…Compound V was prepared from the reaction of 1-methylimidazole with b-propiolactone, [14] and zwitterions of type VI were first observed as products in the glucose-glycine Maillard reaction, [15] but have subsequently been prepared by the condensation of glyoxal with glycine. [16] The solid-state structure of VI (n = 1) determined by single-crystal X-ray diffraction reveals the presence of CH 2 COO À and CH 2 COOH units. [17] These groups are connected by strong intermolecular O···HÀO hydrogen bonding with O···O = 2.463 , possibly contributing to the high melting (decomposition) point of 290 8C.…”

Section: Introductionmentioning

confidence: 99%

Brønsted Acidic Ionic Liquids and Their Zwitterions: Synthesis, Characterization and pK_a Determination

Fei

Zhao

Geldbach

et al. 2004

Chemistry A European J

263

183

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Imidazolium chlorides with one or two carboxylic acid substituent groups, 1-methyl-3-alkylcarboxylic acid imidazolium chloride, [Me[(CH2)nCOOH]im]Cl (n=1, 3), and 1,3-dialkylcarboxylic acid imidazolium chloride, [[(CH2)nCOOH]2im]Cl (n=1, 3), have been synthesized via their corresponding acid esters. Deprotonation of the carboxylic acid functionalized imidazolium chlorides with triethylamine affords the corresponding zwitterions [Me[(CH2)nCOO]im] (n=1, 3) and [[(CH2)nCOOH][(CH2)nCOO]im] (n=1, 3). Subsequent reaction of the zwitterions with strong acids gives the new imidazolium salts [Me[(CH2)nCOOH]im]X (n=1, 3; X=BF4, CF3SO3) and [[(CH2)nCOOH]2im]X (n=1, 3; X=BF4, CF3SO3), which exhibit melting points as low as -61 degrees C. The solid-state structures of two of the carboxylic acid functionalized imidazolium salts have been determined by single-crystal X-ray diffraction analysis. Extensive hydrogen bonding is present between the chloride and the imidazolium, with eight Cl.H interactions below 3 A. The pK(a) values of all the salts, determined by potentiometric titration, lie between 1.33 and 4.59 at 25 degrees C.

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New Imidazoles Formed in Nonenzymatic Browning Reactions

Cited by 34 publications

References 16 publications

Ionic Solid‐State Dimers and Polymers Derived from Imidazolium Dicarboxylic Acids

Ionic Solid‐State Dimers and Polymers Derived from Imidazolium Dicarboxylic Acids

Protein Cross-linking by the Maillard Reaction

Brønsted Acidic Ionic Liquids and Their Zwitterions: Synthesis, Characterization and pK_a Determination

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New Imidazoles Formed in Nonenzymatic Browning Reactions

Cited by 34 publications

References 16 publications

Ionic Solid‐State Dimers and Polymers Derived from Imidazolium Dicarboxylic Acids

Ionic Solid‐State Dimers and Polymers Derived from Imidazolium Dicarboxylic Acids

Protein Cross-linking by the Maillard Reaction

Brønsted Acidic Ionic Liquids and Their Zwitterions: Synthesis, Characterization and pKa Determination

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Brønsted Acidic Ionic Liquids and Their Zwitterions: Synthesis, Characterization and pK_a Determination