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1.
Molecules ; 27(15)2022 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-35956748

RESUMO

In this paper, the photochemistry of glyoxal-hydroxylamine (Gly-HA) complexes is studied using FTIR matrix isolation spectroscopy and ab initio calculations. The irradiation of the Gly-HA complexes with the filtered output of a mercury lamp (λ > 370 nm) leads to their photoconversion to hydroxyketene-hydroxylamine complexes and the formation of hydroxy(hydroxyamino)acetaldehyde with a hemiaminal structure. The first product is the result of a double hydrogen exchange reaction between the aldehyde group of Gly and the amino or hydroxyl group of HA. The second product is formed as a result of the addition of the nitrogen atom of HA to the carbon atom of one aldehyde group of Gly, followed by the migration of the hydrogen atom from the amino group of hydroxylamine to the oxygen atom of the carbonyl group of glyoxal. The identification of the products is confirmed by deuterium substitution and by MP2 calculations of the structures and vibrational spectra of the identified species.


Assuntos
Glioxal , Hidrogênio , Ligação de Hidrogênio , Hidroxilamina , Hidroxilaminas
2.
Molecules ; 27(15)2022 Jul 29.
Artigo em Inglês | MEDLINE | ID: mdl-35956815

RESUMO

Due to its carcinogenic properties, the presence of formaldehyde in resins and other industrial products has been a subject of great concern in recent years. The presented review focuses on modern alternatives for the production of wood-based panels; i.e., substitutes for formaldehyde in the production of amino and phenolic resins, as well as novel hardeners for formaldehyde-free wood adhesives. Solutions in which formaldehyde in completely replaced are presented in this review. Recent advances indicate that it is possible to develop new formaldehyde-free systems of resins with compatible hardeners. The formaldehyde substitutes that have primarily been tested are glyoxal, glutaraldehyde, furfural, 5-hydroxymethylfurfural, and dimethoxyethanal. The use of such substitutes eliminates the problem of free formaldehyde emission originating from the resin used in the production of wood-based panels. However, these alternatives are mostly characterized by worse reactivity, and, as a result, the use of formaldehyde-free resins may affect the mechanical and strength properties of wood-based panels. Nonetheless, there are still many substantial challenges for the complete replacement of formaldehyde and further research is needed, especially in the field of transferring the technology to industrial practice.


Assuntos
Adesivos , Madeira , Glioxal , Indústrias , Resinas Vegetais
3.
Food Chem ; 395: 133576, 2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-35802973

RESUMO

This study investigated the Maillard reaction of infant formulas (IFs) produced by four thermal treatments during simulated consumption storage. Among the four sterilization conditions, seventy-five degrees, 2 min was considered the optimal sterilization treatment. The loss of available lysine, 3-DG content and FAST (fluorescence of advanced Maillard products and soluble tryptophan) index was lower in the initial IF produced by this treatment. After storage at 37 °C, 57% RH, the largest loss of available lysine was 71.41%. 5-hydroxymethylfurfural content increased to 7.28 mg/100 g with storage temperature and time, regardless of humidity. The content of α­dicarbonyl compounds fluctuated during storage, and it was estimated that the maximum daily intake was 7.05 mg for 3-deoxyglucuronide and 3.6 mg for glyoxal. The average Nε-carboxymethyllysine concentration during storage at 37 °C was 615.844 ng/mL. At 37 °C, 75% RH, the highest FAST index was 87.11% and ΔE* was 29.95. Compared with thermal treatment, unfavorable storage conditions further promote the occurrence of the Maillard reaction. In particular, the storage temperature should be strictly controlled.


Assuntos
Fórmulas Infantis , Reação de Maillard , Produtos Finais de Glicação Avançada , Glioxal , Humanos , Lactente , Lisina
4.
Food Chem ; 395: 133592, 2022 Nov 30.
Artigo em Inglês | MEDLINE | ID: mdl-35810628

RESUMO

Chemical conversions of reducing sugars and amino compounds induce the formation of heterogenous, high-molecular-weight colorants ('melanoidins') with widely unknown chemical structures. Model experiments of reactive intermediates have proven to be suitable for unravelling the formation mechanisms of colored reaction products. Here, the active methylene norfuraneol was selected and incubated individually as well as in combination with glyoxal, glycolaldehyde, and acetaldehyde at elevated temperatures. Photometric and chromatographic methods as well as mass spectrometry were used to analyze the colored reaction products and reveal the reactivity of different carbonyls regarding the formation of heterogenous oligomers. Aqueous solutions of norfuraneol and glyoxal exceeded the color formation of all other model reaction systems and it could be shown that the initial reactants as well as their degradation products were incorporated into the colorants. The colored oligomers described herein were composed of carbohydrate-based intermediates of the Maillard reaction and defined as melanoidin precursors or pre-melanoidins.


Assuntos
Carboidratos , Reação de Maillard , Glioxal
5.
Int J Mol Sci ; 23(14)2022 Jul 14.
Artigo em Inglês | MEDLINE | ID: mdl-35887131

RESUMO

Brain vascular staining is very important for understanding cerebrovascular pathologies. 4% paraformaldehyde is considered the gold standard fixation technique for immunohistochemistry and it revolutionized the examination of proteins in fixed tissues. However, this fixation technique produces inconsistent immunohistochemical staining results due to antigen masking. Here, we test a new fixation protocol using 3% glyoxal and demonstrate that this method improves the staining of the brain vasculature, pericytes, and tight junction proteins compared to 4% paraformaldehyde. Use of this new fixation technique will provide more detailed information about vascular protein expressions, their distributions, and colocalizations with other proteins at the molecular level in the brain vasculature.


Assuntos
Barreira Hematoencefálica , Pericitos , Barreira Hematoencefálica/patologia , Encéfalo/irrigação sanguínea , Glioxal/metabolismo , Imuno-Histoquímica , Pericitos/metabolismo , Junções Íntimas/metabolismo
6.
J Agric Food Chem ; 70(29): 9154-9165, 2022 Jul 27.
Artigo em Inglês | MEDLINE | ID: mdl-35849535

RESUMO

The present study aimed to investigate the effects of fructo-, inulin-, and galacto-oligosaccharides (FOS, IOS, and GOS) on forming the Maillard reaction products such as browning, α-dicarbonyl compounds, and advanced glycation end products (AGEs). The model solutions at pH 6.8 containing each carbohydrate (mono-, di-, and oligosaccharides) and whey protein were incubated at 50 °C for 8 weeks. In the IOS model, sugars of DP3 or larger were significantly decreased at 4 weeks, whereas at 6 weeks in the FOS model. The residual amount of GOS after 8 weeks was higher than FOS and IOS; however, a large amount of 3-deoxyglucosone was formed compared to the other models. Nε-Carboxymethyllysine (CML) concentrations in oligosaccharide models were about half of those in monosaccharide and lactose models. The highest concentrations of glyoxal- and methylglyoxal-derived hydroimidazolones 3 (G-H3 and MG-H3) were observed in the IOS model, indicating the involvement of fructose units linked by ß-2 → 1 bonds. G-H3 and MG-H3 quantification could be a useful indicator to reflect the modification of an arginine residue by fructose if used acid-hydrolysis for AGE analysis. CML, G-H3, and MG-H3 were considerably formed even in the FOS model, which has no reducing terminal site, suggesting that degradation products of oligosaccharides probably participated in the formation of AGEs.


Assuntos
Produtos Finais de Glicação Avançada , Reação de Maillard , Frutose , Produtos Finais de Glicação Avançada/química , Glioxal/química , Inulina , Oligossacarídeos/química , Aldeído Pirúvico/metabolismo , Proteínas do Soro do Leite
7.
J Environ Sci (China) ; 122: 92-104, 2022 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-35717094

RESUMO

Formaldehyde (HCHO) and glyoxal (CHOCHO) are important oxidization intermediates of most volatile organic compounds (VOCs), but their vertical evolution in urban areas is not well understood. Vertical profiles of HCHO, CHOCHO, and nitrogen dioxide (NO2) were retrieved from ground-based Multi-Axis Differential Optical Absorption Spectroscopy (MAX-DOAS) observations in Hefei, China. HCHO and CHOCHO vertical profiles prefer to occur at higher altitudes compared to NO2, which might be caused by the photochemistry-oxidation of longer-lived VOCs at higher altitudes. Monthly means of HCHO concentrations were higher in summer, while enhanced amounts of NO2 were mainly observed in winter. CHOCHO exhibited a hump-like seasonal variation, with higher monthly-averaged values not only occurred in warm months (July-August) but also in cold months (November-December). Peak values mainly occurred during noon for HCHO but emerged in the morning for CHOCHO and NO2, suggesting that HCHO is stronger link to photochemistry than CHOCHO. We further use the glyoxal to formaldehyde ratio (GFR) to investigate the VOC sources at different altitudes. The lowest GFR value is almost found in the altitude from 0.2 to 0.4 km, and then rises rapidly as the altitude increases. The GFR results indicate that the largest contributor of the precursor VOC is biogenic VOCs at lower altitudes, while at higher altitudes is anthropogenic VOCs. Our findings provide a lot more insight into VOC sources at vertical direction, but more verification is recommended to be done in the future.


Assuntos
Poluentes Atmosféricos , Compostos Orgânicos Voláteis , Poluentes Atmosféricos/análise , Monitoramento Ambiental/métodos , Formaldeído/análise , Glioxal/análise , Dióxido de Nitrogênio/análise , Análise Espectral , Compostos Orgânicos Voláteis/análise
8.
Food Res Int ; 156: 111142, 2022 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-35651014

RESUMO

The carbonyl trapping activity of bound-polyphenol rich insoluble dietary fiber (BP-IDF) from different whole grains and underlying mechanism of these BP-IDF actions were studied under simulated physiological conditions. We found that the black highland barley BP-IDF exhibited the most pronounced effect in scavenging carbonyls by trapping 88.7%, 72.2%, 95.7%, and 31.4% for methylglyoxal, glyoxal, acrolein, and malondialdehyde within 24 h, respectively. After vitro gastrointestinal digestion, the black highland barley BP-IDF still retained considerable trapping activity for carbonyls. The carbonyl scavenging capacity was reduced by up to 93% after removing bound polyphenols from the black highland barley BP-IDF, which was consistent with the reduction in its total phenolic content. Moreover, the formation of adducts between reactive carbonyl species (RCS) and polyphenols bound to insoluble dietary fiber (IDF) was also detected. Overall, these findings confirmed that IDF-bound polyphenols were still active to trap RCS, indicating the potential benefits of BP-IDF from whole grains as functional ingredients to limit carbonyl stress across the gastrointestinal tract.


Assuntos
Hordeum , Polifenóis , Fibras na Dieta/análise , Glioxal , Fenóis/análise , Grãos Integrais
9.
Food Res Int ; 157: 111358, 2022 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-35761621

RESUMO

Human serum albumin (HSA) being the most prevalent protein in the plasma is extremely vulnerable to glycation. Two flavonoids naringin and naringenin were tested for their effects on the glyoxal and ribose-induced glycation, advanced glycation end products (AGEs) and fibril formation of HSA. The inhibition of the formation of AGEs in the presence of both flavonoids demonstrated their antiglycating properties. The presence of fibrillar aggregates in the glyoxal and ribose modified HSA were also decreased by naringin and naringenin. The explanation for naringenin's stronger antiglycating potential than naringin was further investigated by examining their interactions with HSA. H-bonding and other non-covalent interactions with flavonoids stabilize HSA. Interactions of lysine and arginine residues with flavonoids may prevent the residues from getting modified during glycation process. Naringenin bind to both subdomains IIA and IIIA of HSA, protecting more residues than naringin, which only binds to subdomain IIA, may describe the higher inhibitory activity of naringenin.


Assuntos
Citrus , Glioxal , Citrus/metabolismo , Flavanonas , Flavonoides/metabolismo , Produtos Finais de Glicação Avançada/metabolismo , Glioxal/química , Humanos , Compostos Fitoquímicos , Ribose , Albumina Sérica Humana/química
10.
Steroids ; 185: 109062, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35690119

RESUMO

VNPP433-3ß (compound 2, (3ß-(1H-imidazole-1-yl)-17-(1H-benzimidazole-1-yl)-androsta-5,16-diene), a multitarget anticancer agent has emerged as our lead next generation galeterone analogs (NGGA). Here, we describe a large multi-gram (92 g) scale synthesis of compound 2 starting from the commercially available dehydroepiandrosterone-3-acetate (DHEA, 6) via Galeterone (Gal, 1), in 8 steps with a 26% overall yield and 99.5% purity. The overall yield for the synthesis of Gal from DHEA improved from previously reported 47% to 59%. The advantages of this synthesis are as follows: (1) In the first two steps of Scheme 2, the change of solvents and reagents enabled the isolation of compounds 7 and 8 from heptane triturations, as column chromatography was eliminated in both steps. (2) In step 3 (deformylation) the catalyst required was reduced from 50% to 10% (wt/wt) of compound 8 which enable easy purification of compound 9, with modest increased yield. (3) The fourth step to produce Gal (1) was improved by using methanol, eliminating the use of tetrahydrofuran (THF) and dichloromethane, solvent which may be a problem as residual solvent contaminant. (4) In the final step 8, the imidazole-ring formation, inexpensive glyoxal (40% aqueous solution) was used in the reaction instead of expensive glyoxal trimer dihydrate. The structure of the target product (2, VNPP433-3ß) was established by NMR spectroscopy, mass spectrometry and elemental analysis. Gal and VNPP433-3ß exhibit more potent antiproliferative activities against CWR22Rv1 human prostate cancer cells compared to clinical drugs, Abiraterone and Enzalutamide.


Assuntos
Benzimidazóis , Desidroepiandrosterona , Androstadienos , Benzimidazóis/química , Glioxal , Humanos , Masculino , Solventes
11.
Environ Toxicol ; 37(9): 2269-2280, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35621379

RESUMO

Glyoxal, a reactive carbonyl species, can be generated both endogenously (glucose metabolism) and exogenously (cigarette smoke and food system). Increasing evidence demonstrates that glyoxal exacerbates the development and progression of diabetic nephropathy, but the underlying mechanisms of glyoxal toxicity to human embryonic kidney (HEK293) cells remain unclear. In this work, the molecular mechanisms of glyoxal-induced cytotoxicity in HEK293 cells were explored with network toxicology and cell biology experiments. Network toxicology results showed that oxidative stress and advanced glycation end products (AGEs)/RAGE signaling pathways played a crucial role in glyoxal toxicity. Next, further validation was performed at the cellular level. Glyoxal activated the AGEs-RAGE signaling pathway, caused the increase of cellular ROS, and activated the p38MAPK and JNK signaling pathways, causing cellular oxidative stress. Furthermore, glyoxal caused the activation of the NF-κB signaling pathway and increased the expression of TGF-ß1, indicating that glyoxal caused cellular inflammation. Moreover, glyoxal caused cellular DNA damage accompanied by the activation of DNA damage response pathways. Finally, the mitochondrial apoptosis pathway was activated. The results that obtained in cell biology were consistent with network toxicology, which corroborated each other and together indicated that glyoxal induced HEK293 cells damage via the process of oxidative stress, the AGEs-RAGE pathway, and their associated signaling pathways. This study provides the experimental basis for the cytotoxicity of glyoxal on HEK293 cells.


Assuntos
Produtos Finais de Glicação Avançada , Glioxal , Produtos Finais de Glicação Avançada/metabolismo , Glioxal/metabolismo , Glioxal/toxicidade , Células HEK293 , Humanos , Rim/metabolismo , Estresse Oxidativo
12.
Org Biomol Chem ; 20(22): 4522-4525, 2022 06 08.
Artigo em Inglês | MEDLINE | ID: mdl-35605977

RESUMO

A visible-light-mediated synthesis of α,ß-diamino esters has been developed via the cross coupling of N,N-dimethylanilines with glyoxalic oxime ethers. This protocol involves the generation of α-aminoalkyl radicals under mild reaction conditions, provides α,ß-diamino esters in good to excellent yields, and can be performed on a gram-scale.


Assuntos
Ésteres , Éteres , Compostos de Anilina , Glioxal , Oximas
13.
Int J Mol Sci ; 23(7)2022 Mar 22.
Artigo em Inglês | MEDLINE | ID: mdl-35408807

RESUMO

Glyoxal (GO) and methylglyoxal (MGO) are highly reactive species formed in carbohydrate metabolism. Nε-Carboxymethyllysine (CML) and Nε-carboxyethyllysine (CEL) are considered to be the advanced glycation end-products (AGEs) of L-lysine (Lys) with GO and MGO, respectively. Here, we investigated the reaction of free L-lysine (Lys) with GO and MGO in phosphate buffer (pH 7.4) at 37 °C and 80 °C in detail in the absence of any other chemicals which are widely used to reduce Schiff bases. The concentrations of Lys, GO and MGO used in the experiments were 0.5, 2.5, 5.0, 7.5 and 10 mM. The reaction time ranged between 0 and 240 min. Experiments were performed in triplicate. The concentrations of remaining Lys and of CML and CEL formed in the reaction mixtures were measured by stable-isotope dilution gas chromatography-mass spectrometry (GC-MS). Our experiments showed that CML and CEL were formed at higher concentrations at 80 °C compared to 37 °C. CML was found to be the major reaction product. In mixtures of GO and MGO, MGO inhibited the formation of CML from Lys (5 mM) in a concentration-dependent manner. The highest CML concentration was about 300 µM corresponding to a reaction yield of 6% with respect to Lys. An addition of Lys to GO, MGO and their mixtures resulted in strong reversible decreases in the Lys concentration up to 50%. It is assumed that free Lys reacts rapidly with GO and MGO to form many not yet identified reaction products. Reaction mixtures of Lys and MGO were stronger colored than those of Lys and GO, notably at 80 °C, indicating higher reactivity of MGO towards Lys that leads to polymeric colored MGO species. We have a strong indication of the formation of Nε-(hydroxymethyl)-lysine (HML) as a novel reaction product of Lys methyl ester with MGO. A mechanism is proposed for the formation of HML from Lys and MGO. This mechanism may explain why Lys and GO do not react to form a related product. Preliminary analyses show that HML is formed at higher concentrations than CEL from Lys methyl ester and MGO. No Schiff bases or their hydroxylic precursors were identified as reaction products. In their reactions with Lys, GO and MGO are likely to act both as chemical oxidants on the terminal aldehyde group to a carboxylic group (i.e., R-CHO to R-COOH) and as chemical reductors on labile Schiff bases (R-CH=N-R to R-CH2-NH-R) presumably via disproportionation and hydride transfer. Our study shows that free non-proteinic Lys reacts with GO and MGO to form CML, CEL and HML in very low yield. Whether proteinic Lys also reacts with MGO to form HML residues in proteins remains to be investigated. The physiological occurrence and concentration of HML in biological fluids and tissues and its relation to CML and CEL are elusive and warrant further investigations in health and disease. Chemical synthesis and structural characterization of HML are expected to advance and accelerate the scientific research in this topic.


Assuntos
Glioxal , Aldeído Pirúvico , Ésteres/análise , Cromatografia Gasosa-Espectrometria de Massas , Produtos Finais de Glicação Avançada/química , Concentração de Íons de Hidrogênio , Lisina/análogos & derivados , Lisina/análise , Óxido de Magnésio , Fosfatos , Aldeído Pirúvico/química , Bases de Schiff
14.
Phys Chem Chem Phys ; 24(16): 9394-9402, 2022 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-35384955

RESUMO

The most thermodynamically and kinetically favorable pathways for the formation of 2-methylimidazole (2MI) in the reaction of glyoxal and acetaldehyde with ammonia in aqueous solution have been determined. The formation of 2MI proceeds through a number of successive intermediates of acyclic and cyclic structures, and the most favorable route (thermodynamically and kinetically) for the formation of the imidazole ring is the condensation of amine intermediates, in contrast to the existing concepts of imine structures. The limiting stage is the stage of cyclization involving the intramolecular attack by the amino group of the precyclic intermediate on the carbon atom bound to the hydroxyl group with the simultaneous release of a water molecule according to the SN2 mechanism. Further stages of stepwise dehydration lead to the formation of a cyclic diazine, the intramolecular migration of the proton of the tertiary carbon atom to the nitrogen atom of which completes the formation of 2MI. Experimental studies on the effect of the order of mixing of initial reagents on the 2MI yield confirmed the quantum-chemically substantiated favorable pathway for the formation of 2MI during the interaction of amine intermediates, and also revealed that the selectivity of the 2MI formation is achieved by successive mixing of acetaldehyde with ammonia until the formation of hydroxyamine products and their further interaction with glyoxal.


Assuntos
Acetaldeído , Glioxal , Acetaldeído/química , Aminas , Amônia , Carbono , Glioxal/química , Imidazóis , Termodinâmica
15.
Nutrients ; 14(7)2022 Mar 24.
Artigo em Inglês | MEDLINE | ID: mdl-35405976

RESUMO

α-Dicarbonyl compounds, particularly methylglyoxal (MGO), glyoxal (GO), and 3-deoxyglucosone (3-DG), are highly reactive precursors for the formation of advanced glycation end products (AGEs). They are formed in vivo and during food processing. This study aimed to investigate the role of intracellular glutathione (GSH) levels in the induction of Nrf2-mediated gene expression by α-dicarbonyl compounds. The reactions between α-dicarbonyl compounds (MGO, GO, and 3-DG) and GSH were studied by LC-MS in a cell-free system. It was shown that these three α-dicarbonyl compounds react instantaneously with GSH, with the GSH-mediated scavenging decreasing in the order MGO > GO > 3DG. Furthermore, in a cell-based reporter gene assay MGO, GO, and 3-DG were able to induce Nrf2-mediated gene expression in a dose-dependent manner. Modulation of intracellular GSH levels showed that the cytotoxicity and induction of the Nrf2-mediated pathway by MGO, GO and 3-DG was significantly enhanced by depletion of GSH, while a decrease in Nrf2-activation by MGO and GO but not 3-DG was observed upon an increase of the cellular GSH levels. Our results reveal subtle differences in the role of GSH in protection against the three typical α-dicarbonyl compounds and in their induction of Nrf2-mediated gene expression, and point at a dual biological effect of the α-dicarbonyl compounds, being reactive toxic electrophiles and -as a consequence- able to induce Nrf2-mediated protective gene expression, with MGO being most reactive.


Assuntos
Produtos Finais de Glicação Avançada , Fator 2 Relacionado a NF-E2 , Expressão Gênica , Glutationa , Glioxal/farmacologia , Óxido de Magnésio , Fator 2 Relacionado a NF-E2/genética , Aldeído Pirúvico
16.
Anal Chim Acta ; 1206: 339612, 2022 May 08.
Artigo em Inglês | MEDLINE | ID: mdl-35473884

RESUMO

Direct and rapid analysis of glyoxal by soft ionization mass spectrometry remains a great challenge due to its low ionization efficiency in existing soft ionization techniques, such as proton transfer reaction (PTR) and photoionization (PI). In this work, we developed a new VUV lamp-based cluster-mediated CH2Br2+ chemical ionization (CMCI) source for time-of-flight mass spectrometry (TOFMS), which was accomplished by employing photoionization-generated CH2Br2+ as the reactant ion and co-sampling of glyoxal with high-concentration ethanol (EtOH). The signal intensity of glyoxal could be enhanced by more than 2 orders of magnitude by generating protonated cluster ion [Glx·EtOH·H]+. Density function theory (DFT) calculations was performed to obtain the most stable structure of neutral glyoxal-ethanol cluster and confirm that the ionization energy (IE) of glyoxal-ethanol cluster was significantly lower than that of glyoxal and CH2Br2 molecules, which makes it possible for effective ionization of glyoxal. The ionization efficiency of glyoxal could be dramatically enhanced via ion-molecule reaction between CH2Br2+ and glyoxal-ethanol cluster, as larger ionization cross section of glyoxal-ethanol cluster than glyoxal molecule might be achieved. The cluster-mediated signal enhanced effect was also verified by using other alcohols, such as methanol and isopropanol. Consequently, the limit of quantitation (LOQ, S/N = 10) down to 0.17 ppbv for gas-phase glyoxal was achieved. The analytical capacity of this system was demonstrated by trace analysis of glyoxal in food contact papers, exhibiting new insights and wide potentials of chemical ionization and photoionization mass spectrometry for VOCs measurement with higher sensitivity and wider detectable sample range.


Assuntos
Glioxal , Prótons , Fenômenos Químicos , Etanol , Espectrometria de Massas/métodos
17.
J Agric Food Chem ; 70(14): 4434-4444, 2022 Apr 13.
Artigo em Inglês | MEDLINE | ID: mdl-35348319

RESUMO

Short-chained α-hydroxycarbonyl compounds such as glycolaldehyde (GA) and its oxidized counterpart glyoxal (GX) are known as potent glycating agents. Here, a novel fluorescent lysine-lysine cross-link 1-(5-amino-5-carboxypentyl)-3-(5-amino-5-carboxy-pentylamino)pyridinium salt (meta-DLP) was synthesized and its structure unequivocally proven by 1H NMR, 13C-NMR attached proton test, and 2D NMR. Further characterization of chemical properties and mechanistic background was obtained in comparison to the known monovalent protein modification 2-ammonio-6-(3-oxidopyridinium-1-yl)hexanoate (OP-lysine). Identification and quantitation in various sugar incubations with N2-t-Boc-lysine revealed a novel alternative formation pathway for both advanced glycation end products (AGEs) by the interplay of both carbonyl compounds, GA and GX, which was confirmed by isotope labeling experiments. The concentration of pyridinium AGEs was about 1000-fold lower compared to the well-established N6-carboxymethyl lysine. However, pyridinium AGEs were shown to lead to the photosensitized generation of singlet oxygen in irradiation experiments, which was verified by the detection of 3,3'-(naphthalene-1,4-diyl)-dipropionate endoperoxide. Furthermore, meta-DLP was identified in hydrolyzed potato chip proteins by collision-induced dissociation mass spectrometry after HPLC enrichment.


Assuntos
Glioxal , Lisina , Acetaldeído/análogos & derivados , Produtos Finais de Glicação Avançada/química , Glioxal/química , Lisina/química , Reação de Maillard
18.
Food Chem ; 382: 132500, 2022 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-35245757

RESUMO

The generation of pyrazines in a binary methionine/glucose (Met/Glc) mixture and corresponding methionine/glucose-derived Amadori rearrangement product (MG-ARP) was studied. Quantitative analyses of pyrazines and methional revealed that MG-ARP generated more methional compared to Met/Glc, whereas lower content and fewer species of pyrazines were observed in the MG-ARP model. Comparing the availability of α-dicarbonyl compounds generated from the Met/Glc model, methylglyoxal (MGO) was a considerably effective α-dicarbonyl compound for the formation of pyrazines during MG-ARP degradation, but glyoxal (GO) produced from MG-ARP did not effectively participate in the corresponding formation of pyrazines due to the asynchrony on the formation of GO and recovered Met. Diacetyl (DA) content was not high enough to form corresponding pyrazines in the MG-ARP model. The insufficient interaction of precursors and rapid drops in pH limited the formation of pyrazines during MG-ARP degradation. Increasing reaction temperature could reduce the negative inhibitory effect by promoting the content of precursors.


Assuntos
Reação de Maillard , Metionina , Glucose , Glioxal , Pirazinas/química
19.
Sci Rep ; 12(1): 4268, 2022 03 11.
Artigo em Inglês | MEDLINE | ID: mdl-35277529

RESUMO

Reactive glucose degradation products (GDPs) are formed during heat sterilization of glucose-containing peritoneal dialysis fluids (PDFs) and may induce adverse clinical effects. Long periods of storage and/or transport of PDFs before use may lead to de novo formation or degradation of GDPs. Therefore, the present study quantified the GDP profiles of single- and double-chamber PDFs during storage. Glucosone, 3-deoxyglucosone (3-DG), 3-deoxygalactosone (3-DGal), 3,4-dideoxyglucosone-3-ene (3,4-DGE), glyoxal, methylglyoxal (MGO), acetaldehyde, formaldehyde, and 5-hydroxymethylfurfural (5-HMF) were quantified by two validated UHPLC-DAD methods after derivatization with o-phenylenediamine (dicarbonyls) or 2,4-dinitrophenylhydrazine (monocarbonyls). The PDFs were stored at 50 °C for 0, 1, 2, 4, 13, and 26 weeks. The total GDP concentration of single-chamber PDFs did not change considerably during storage (496.6 ± 16.0 µM, 0 weeks; 519.1 ± 13.1 µM, 26 weeks), but individual GDPs were affected differently. 3-DG (- 82.6 µM) and 3-DGal (- 71.3 µM) were degraded, whereas 5-HMF (+ 161.7 µM), glyoxal (+ 32.2 µM), and formaldehyde (+ 12.4 µM) accumulated between 0 and 26 weeks. Acetaldehyde, glucosone, MGO, and 3,4-DGE showed time-dependent formation and degradation. The GDP concentrations in double-chamber fluids were generally lower and differently affected by storage. In conclusion, the changes of GDP concentrations during storage should be considered for the evaluation of clinical effects of PDFs.


Assuntos
Óxido de Magnésio , Diálise Peritoneal , Acetaldeído , Soluções para Diálise/metabolismo , Formaldeído , Glucose/metabolismo , Glioxal , Aldeído Pirúvico
20.
ACS Chem Biol ; 17(4): 756-761, 2022 04 15.
Artigo em Inglês | MEDLINE | ID: mdl-35294181

RESUMO

Because of their long half-lives and highly nucleophilic tails, histones are particularly susceptible to accumulating nonenzymatic covalent modifications, such as glycation. The resulting modifications can have profound effects on cellular physiology due to the regulatory role histones play in all DNA-templated processes; however, the complexity of Maillard chemistry on proteins makes tracking and enriching for glycated proteins a challenging task. Here, we characterize glyoxal (GO) modifications on histones using quantitative proteomics and an aniline-derived GO-reactive probe. In addition, we leverage this chemistry to demonstrate that the glycation regulatory proteins DJ-1 and GLO1 reduce levels of histone GO adducts. Finally, we employ a two-round pull-down method to enrich histone H3 GO glycation and map these adducts to specific chromatin regions.


Assuntos
Glioxal , Histonas , Cromatina , Glicosilação , Glioxal/química , Glioxal/metabolismo , Histonas/metabolismo , Proteômica
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