Birnessite catalysis of the Maillard Reaction: Its significance in natural humification

NASA Astrophysics Data System (ADS)

Jokic, A.; Frenkel, A. I.; Vairavamurthy, M. A.; Huang, P. M.

Although mineral colloids are known to play a significant role in transforming organic matter in soils and sediments, there still are many gaps in our understanding of the mechanisms of organic-mineral interactions. In this study, we investigated the role of a major oxide-mineral birnessite (a form of Mn(IV) oxide) in catalyzing the condensation reaction between sugars and amino acids, the Maillard reaction, for forming humic substances. The Maillard reaction is perceived to be a major pathway in natural humification. Using a suite of spectroscopic methods (including ESR, XANES, EXAFS and 13C NMR), our results show that Mn(IV) oxide markedly accelerates the Maillard reaction between glucose and glycine at ranges of temperatures and pH typical of natural environments. These results demonstrate the importance of manganese oxide catalysis in the Maillard reaction, and its significance in the natural abiotic formation of humic substances.

High-Pressure-High-Temperature Processing Reduces Maillard Reaction and Viscosity in Whey Protein-Sugar Solutions.

PubMed

Avila Ruiz, Geraldine; Xi, Bingyan; Minor, Marcel; Sala, Guido; van Boekel, Martinus; Fogliano, Vincenzo; Stieger, Markus

2016-09-28

The aim of the study was to determine the influence of pressure in high-pressure-high-temperature (HPHT) processing on Maillard reactions and protein aggregation of whey protein-sugar solutions. Solutions of whey protein isolate containing either glucose or trehalose at pH 6, 7, and 9 were treated by HPHT processing or conventional high-temperature (HT) treatments. Browning was reduced, and early and advanced Maillard reactions were retarded under HPHT processing at all pH values compared to HT treatment. HPHT induced a larger pH drop than HT treatments, especially at pH 9, which was not associated with Maillard reactions. After HPHT processing at pH 7, protein aggregation and viscosity of whey protein isolate-glucose/trehalose solutions remained unchanged. It was concluded that HPHT processing can potentially improve the quality of protein-sugar-containing foods, for which browning and high viscosities are undesired, such as high-protein beverages.

Maillard reaction products from chitosan-xylan ionic liquid solution.

PubMed

Luo, Yuqiong; Ling, Yunzhi; Wang, Xiaoying; Han, Yang; Zeng, Xianjie; Sun, Runcang

2013-10-15

A facile method is reported to prepare Maillard reaction products (MRPs) from chitosan and xylan in co-solvent ionic liquid. UV absorbance and fluorescence changes were regarded as indicators of the occurrence of Maillard reaction. FT-IR, NMR, XRD and TG were used to investigate the structure of chitosan-xylan conjugate. The results revealed that when chitosan reacted with xylan in ionic liquid, the hydrogen bonds in chitosan were destroyed, the facts resulted in the formation of chitosan-xylan MRPs. Moreover, when the mass ratio of chitosan to xylan was 1:1, the Maillard reaction proceeded easily. In addition, relatively high antioxidant property was also noted for the chitosan-xylan conjugate with mass ratio 1:1. So the obtained chitosan-xylan MRP is a promising antioxidant agent for food industry. Copyright © 2013 Elsevier Ltd. All rights reserved.

Improvement of ACE inhibitory activity of casein hydrolysate by Maillard reaction with xylose.

PubMed

Hong, Xu; Meng, Jun; Lu, Rong-Rong

2015-01-01

The Maillard reaction is widely used to improve the functional properties or biological activities of food. The purpose of this study was to investigate the effect of the Maillard reaction on angiotensin I converting enzyme (ACE) inhibitory activity in a casein hydrolysate-xylose system. Two-step hydrolysis was used to prepare casein ACE inhibitory peptides. Maillard reaction products (MRPs) were prepared by heating hydrolyzed casein with xylose at pH 8.0, 110 °C for up to 16 h. The results showed that the content of free amino group decreased (P < 0.05); however, browning intensity and absorbance at 294 nm increased because of the Maillard reaction (P < 0.05). The ACE inhibitory activity improved greatly within 2 h (from 63.48% to 90.23%), which was mainly due to carbonyl ammonia condensation reaction in the MRPs. The study shows that the Maillard reaction under appropriate conditions can improve the ACE inhibitory activity of casein hydrolysate effectively. © 2014 Society of Chemical Industry.

Maillard reaction of lactose and fluoxetine hydrochloride, a secondary amine.

PubMed

Wirth, D D; Baertschi, S W; Johnson, R A; Maple, S R; Miller, M S; Hallenbeck, D K; Gregg, S M

1998-01-01

Analysis of commercially available generic formulations of fluoxetine HCl revealed the presence of lactose as the most common excipient. We show that such formulations are inherently less stable than formulations with starch as the diluent due to the Maillard reaction between the drug, a secondary amine hydrochloride, and lactose. The Amadori rearrangement product was isolated and characterized; the characterization was aided by reduction with sodium borohydride and subsequent characterization of this reduced adduct. The lactose-fluoxetine HCl reaction was examined in aqueous ethanol and in the solid state, in which factors such as water content, lubricant concentration, and temperature were found to influence the degradation. N-Formylfluoxetine was identified as a major product of this Maillard reaction and it is proposed that N-formyl compounds be used as markers for this drug-excipient interaction since they are easy to prepare synthetically. Many characteristic volatile products of the Maillard reaction have been identified by GC/MS, including furaldehyde, maltol, and 2,3-dihydro-3,5-dihydroxy-6-methyl-4 H-pyran-4-one. Close similarity between the degradation products of simple mixtures and formulated generic products was found; however, at least one product decomposed at a rate nearly 10 times that predicted from the simple models. Maillard products have also been identified in unstressed capsules. The main conclusion is that drugs which are secondary amines (not just primary amines as sometimes reported) undergo the Maillard reaction with lactose under pharmaceutically relevant conditions. This finding should be considered during the selection of excipients and stability protocols for drugs which are secondary amines or their salts, just as it currently is for primary amines.

The dual effects of Maillard reaction and enzymatic hydrolysis on the antioxidant activity of milk proteins.

PubMed

Oh, N S; Lee, H A; Lee, J Y; Joung, J Y; Lee, K B; Kim, Y; Lee, K W; Kim, S H

2013-08-01

The objective of this study was to determine the enhanced effects on the biological characteristics and antioxidant activity of milk proteins by the combination of the Maillard reaction and enzymatic hydrolysis. Maillard reaction products were obtained from milk protein preparations, such as whey protein concentrates and sodium caseinate with lactose, by heating at 55°C for 7 d in sodium phosphate buffer (pH 7.4). The Maillard reaction products, along with untreated milk proteins as controls, were hydrolyzed for 0 to 3h with commercial proteases Alcalase, Neutrase, Protamex, and Flavorzyme (Novozymes, Bagsværd, Denmark). The antioxidant activity of hydrolyzed Maillard reaction products was determined by reaction with 2,2'-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt, their 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity, and the ability to reduce ferric ions. Further characteristics were evaluated by the o-phthaldialdehyde method and sodium dodecyl sulfate-PAGE. The degree of hydrolysis gradually increased in a time-dependent manner, with the Alcalase-treated Maillard reaction products being the most highly hydrolyzed. Radical scavenging activities and reducing ability of hydrolyzed Maillard reaction products increased with increasing hydrolysis time. The combined products of enzymatic hydrolysis and Maillard reaction showed significantly greater antioxidant activity than did hydrolysates or Maillard reaction products alone. The hydrolyzed Maillard reaction products generated by Alcalase showed significantly higher antioxidant activity when compared with the other protease products and the antioxidant activity was higher for the whey protein concentrate groups than for the sodium caseinate groups. These findings indicate that Maillard reaction products, coupled with enzymatic hydrolysis, could act as potential antioxidants in the pharmaceutical, food, and dairy industries. Copyright © 2013 American Dairy Science Association

Investigations on the Maillard reaction of dextrins during aging of Pilsner type beer.

PubMed

Rakete, Stefan; Klaus, Alexander; Glomb, Marcus A

2014-10-08

Although Maillard reaction plays a pivotal role during preparation of food, only few investigations concerning the role of carbohydrate degradation in beer aging have been carried out. The formation of Maillard specific precursor structures and their follow-up products during degradation of low molecular carbohydrate dextrins in the presence of proline and lysine was studied in model incubations and in beer. Twenty-one α-dicarbonyl compounds were identified and quantitated as reactive intermediates. The oxidative formation of 3-deoxypentosone as the precursor of furfural from oligosaccharides was verified. N-Carboxymethylproline and N-formylproline were established as novel proline derived Maillard advanced glycation end products. Formation of N-carboxymethylproline and furfural responded considerably to the presence of oxygen and was positively correlated to aging of Pilsner type beer. The present study delivers an in-depth view on the mechanisms behind the formation of beer relevant aging parameters.

The Maillard Reaction Reduced the Sensitization of Tropomyosin and Arginine Kinase from Scylla paramamosain, Simultaneously.

PubMed

Han, Xin-Yu; Yang, Huang; Rao, Shi-Tao; Liu, Guang-Yu; Hu, Meng-Jun; Zeng, Bin-Chang; Cao, Min-Jie; Liu, Guang-Ming

2018-03-21

The Maillard reaction was established to reduce the sensitization of tropomyosin (TM) and arginine kinase (AK) from Scylla paramamosain, and the mechanism of the attenuated sensitization was investigated. In the present study, the Maillard reaction conditions were optimized for heating at 100 °C for 60 min (pH 8.5) with arabinose. A low level of allergenicity in mice was shown by the levels of allergen-specific antibodies, and more Th1 and less Th2 cells cytokines produced and associated transcription factors with the Maillard reacted allergen (mAllergen). The tolerance potency in mice was demonstrated by the increased ratio of Th1/Th2 cytokines. Moreover, mass spectrometry analysis showed that some key amino acids of IgE-binding epitopes (K 112 , R 125 , R 133 of TM; K 33 , K 118 , R 202 of AK) were modified by the Maillard reaction. The Maillard reaction with arabinose reduced the sensitization of TM and AK, which may be due to the masked epitopes.

The influence of emulsion structure on the Maillard reaction of ghee.

PubMed

Newton, Angela E; Fairbanks, Antony J; Golding, Matt; Andrewes, Paul; Gerrard, Juliet A

2015-04-15

Food systems, such as cream and butter, have an emulsion or emulsion-like structure. When these food emulsions are heated to high temperatures to make products such as ghee, the Maillard reaction forms a range of volatile flavour compounds. The objective of this paper was to unravel the specific influence of emulsion structure on the Maillard reaction pathways that occur during the cooking of ghee using model systems. Switching the dispersed phase from oil to water provided a means of altering the ratios of volatile compounds produced in the cooked samples. The oil-in-water emulsion generated a volatile compound profile similar to that of the fat containing two phase model matrix, whereas the water-in-oil emulsion produced a different ratio of these compounds. The ability to generate different volatile compound profiles through the use of inverted emulsion structures could point to a new avenue for control of the Maillard reaction in high temperature food systems. Copyright © 2014 Elsevier Ltd. All rights reserved.

A study of the tyramine/glucose Maillard reaction: Variables, characterization, cytotoxicity and preliminary application.

PubMed

Jiang, Wei; Chen, Yaxin; He, Xiaoxia; Hu, Shiwei; Li, Shijie; Liu, Yu

2018-01-15

The tyramine/glucose Maillard reaction was proposed as an emerging tool for tyramine reduction in a model system and two commercial soy sauce samples. The model system was composed of tyramine and glucose in buffer solutions with or without NaCl. The results showed that tyramine was reduced in the model system, and the reduction rate was affected by temperature, heating time, initial pH value, NaCl concentration, initial glucose concentration and initial tyramine concentration. Changes in fluorescence intensity and ultraviolet-visible (UV-vis) absorption spectra showed three stages of the Maillard reaction between tyramine and glucose. Cytotoxicity assay demonstrated that tyramine/glucose Maillard reaction products (MRPs) were significantly less toxic than that of tyramine (p<0.05). Moreover, tyramine concentration in soy sauce samples was significantly reduced when heated with the addition of glucose (p<0.05). Experimental results showed that the tyramine/glucose Maillard reaction is a promising method for tyramine reduction in foods. Copyright © 2017 Elsevier Ltd. All rights reserved.

Functional improvements in dried egg white through the Maillard reaction.

PubMed

Handa, A; Kuroda, N

1999-05-01

The effects of the Maillard reaction on the functional properties of dried egg white (DEW) were investigated. Maillard-reacted DEW (M-DEW) was prepared by storing sugar-preserved DEW (SP-DEW) at 55 degrees C and 35% relative humidity for 0-12 days. The M-DEW developed an excellent gelling property, and hydrogen sulfide production from heat-induced M-DEW gels decreased. Surface sulfhydryl (SH) group content of M-DEW increased while total SH group and alpha-helix contents decreased with increasing heating time in the dry state. Breaking strength, breaking strain, water-holding capacity, and hydrogen sulfide of heat-induced M-DEW gels significantly correlated with surface and total SH group contents in M-DEW. SDS-PAGE revealed that M-DEW proteins were polymerized in which covalent bonds were involved. The present study demonstrated that the Maillard reaction partially unfolds and polymerizes proteins of SP-DEW and, consequently, improved gelling property of SP-DEW under certain controlled conditions.

Regulatory Notes on Impact of Excipients on Drug Products and the Maillard Reaction.

PubMed

Chowdhury, Dipak K; Sarker, Haripada; Schwartz, Paul

2018-02-01

In general, it is an important criterion that excipients remain inert throughout the shelf life of the formulated pharmaceutical product. However, depending on the functionality in chemical structure of active drug and excipients, they may undergo interaction. The well-known Maillard reaction occurs between a primary amine with lactose at high temperature to produce brown pigments. The reactivity of Maillard reaction may vary depending on the concentration as well as other conditions. Commercially, there are products where the active pharmaceutical ingredient is a primary amine and contains less than 75% lactose along with inactive excipients. This product does not show Maillard reaction during its shelf life of around 2 years at ambient conditions. However, when the same type of product contains more than 95 % lactose as an excipient, then there is a possibility of interactions though it is not visible in the initial year. Therefore, this regulatory note discusses involvement of different factors of a known drug-excipient interactions with case studies and provides an overview on how the concentration of lactose in the pharmaceutical product is important in addition to temperature and moisture in Maillard reaction.

Optimization of Maillard Reaction in Model System of Glucosamine and Cysteine Using Response Surface Methodology

PubMed Central

Arachchi, Shanika Jeewantha Thewarapperuma; Kim, Ye-Joo; Kim, Dae-Wook; Oh, Sang-Chul; Lee, Yang-Bong

2017-01-01

Sulfur-containing amino acids play important roles in good flavor generation in Maillard reaction of non-enzymatic browning, so aqueous model systems of glucosamine and cysteine were studied to investigate the effects of reaction temperature, initial pH, reaction time, and concentration ratio of glucosamine and cysteine. Response surface methodology was applied to optimize the independent reaction parameters of cysteine and glucosamine in Maillard reaction. Box-Behnken factorial design was used with 30 runs of 16 factorial levels, 8 axial levels and 6 central levels. The degree of Maillard reaction was determined by reading absorption at 425 nm in a spectrophotometer and Hunter’s L, a, and b values. ΔE was consequently set as the fifth response factor. In the statistical analyses, determination coefficients (R2) for their absorbance, Hunter’s L, a, b values, and ΔE were 0.94, 0.79, 0.73, 0.96, and 0.79, respectively, showing that the absorbance and Hunter’s b value were good dependent variables for this model system. The optimum processing parameters were determined to yield glucosamine-cysteine Maillard reaction product with higher absorbance and higher colour change. The optimum estimated absorbance was achieved at the condition of initial pH 8.0, 111°C reaction temperature, 2.47 h reaction time, and 1.30 concentration ratio. The optimum condition for colour change measured by Hunter’s b value was 2.41 h reaction time, 114°C reaction temperature, initial pH 8.3, and 1.26 concentration ratio. These results can provide the basic information for Maillard reaction of aqueous model system between glucosamine and cysteine. PMID:28401086

Optimization of Maillard Reaction in Model System of Glucosamine and Cysteine Using Response Surface Methodology.

PubMed

Arachchi, Shanika Jeewantha Thewarapperuma; Kim, Ye-Joo; Kim, Dae-Wook; Oh, Sang-Chul; Lee, Yang-Bong

2017-03-01

Sulfur-containing amino acids play important roles in good flavor generation in Maillard reaction of non-enzymatic browning, so aqueous model systems of glucosamine and cysteine were studied to investigate the effects of reaction temperature, initial pH, reaction time, and concentration ratio of glucosamine and cysteine. Response surface methodology was applied to optimize the independent reaction parameters of cysteine and glucosamine in Maillard reaction. Box-Behnken factorial design was used with 30 runs of 16 factorial levels, 8 axial levels and 6 central levels. The degree of Maillard reaction was determined by reading absorption at 425 nm in a spectrophotometer and Hunter's L, a, and b values. ΔE was consequently set as the fifth response factor. In the statistical analyses, determination coefficients (R 2 ) for their absorbance, Hunter's L, a, b values, and ΔE were 0.94, 0.79, 0.73, 0.96, and 0.79, respectively, showing that the absorbance and Hunter's b value were good dependent variables for this model system. The optimum processing parameters were determined to yield glucosamine-cysteine Maillard reaction product with higher absorbance and higher colour change. The optimum estimated absorbance was achieved at the condition of initial pH 8.0, 111°C reaction temperature, 2.47 h reaction time, and 1.30 concentration ratio. The optimum condition for colour change measured by Hunter's b value was 2.41 h reaction time, 114°C reaction temperature, initial pH 8.3, and 1.26 concentration ratio. These results can provide the basic information for Maillard reaction of aqueous model system between glucosamine and cysteine.

Effects of the Maillard Reaction on the Immunoreactivity of Amandin in Food Matrices.

PubMed

Chhabra, Guneet S; Liu, Changqi; Su, Mengna; Venkatachalam, Mahesh; Roux, Kenneth H; Sathe, Shridhar K

2017-10-01

Amandin is the major storage protein and allergen in almond seeds. Foods, containing almonds, subjected to thermal processing typically experience Maillard browning reaction. The resulting destruction of amino groups, protein glycation, and/or denaturation may alter amandin immunoreactivity. Amandin immunoreactivity of variously processed almond containing foods was therefore the focus of the current investigation. Commercial and laboratory prepared foods, including those likely to have been subjected to Maillard browning, were objectively assessed by determining Hunter L * , a * , b * values. The L * values for the tested samples were in the range of 31.75 to 85.28 consistent with Maillard browning. Three murine monoclonal antibodies, 4C10, 4F10, and 2A3, were used to determine the immunoreactivity of the targeted samples using immunoassays (ELISA, Western blot, dot blot). The tested foods did not exhibit cross-reactivity indicating that the immunoassays were amandin specific. For sandwich ELISAs, ratio (R) of sample immunoreactivity to reference immunoreactivity was calculated. The ranges of R values were 0.67 to 15.19 (4C10), 1.00 to 11.83 (4F10), and 0.77 to 23.30 (2A3). The results of dot blot and Western blot were consistent with those of ELISAs. Results of these investigations demonstrate that amandin is a stable marker protein for almond detection regardless of the degree of amandin denaturation and/or destruction as a consequence of Maillard reaction encountered under the tested processing conditions. Foods containing almond are often subjected to processing prior to consumption. Amandin, the major allergen in almond, may experience Maillard reaction. Understanding the change in amandin immunoreactivity as a result of Maillard reaction is important for amandin detection and production of hypoallergenic food products. © 2017 Institute of Food Technologists®.

Discovery of Amadori-Type Conjugates in a Peptide Maillard Reaction and Their Corresponding Influence on the Formation of Pyrazines.

PubMed

Zou, Tingting; Liu, Jianbin; Song, Huanlu; Liu, Ye

2018-06-01

Knowledge of the role of peptides in the Maillard reaction is rather limited. In this study, peptide Maillard reaction model systems were established. Volatile and nonvolatile MRPs (Maillard reaction products) were investigated by GC-O-MS and LC-MS. Carbohydrate module labeling (CAMOLA) experiments were performed to elucidate the carbon skeleton of these compounds. Results showed that the peptide reaction system generated more pyrazines than the free amino acid group. Several new Amadori-type conjugates were identified as novel Maillard reaction products that could greatly influence the formation of pyrazines. Our work suggested anew mechanism involving these Amadori-type conjugates and subsequent investigation revealed that the conjugates could be important intermediate products in the reaction between dicarbonyl and dipeptide. Our findings demonstrate anew pyrazine generation mechanism in the dipeptide Maillard reaction. We found that a dipeptide Maillard reaction system generated more pyrazines than a reaction system composed of free amino acids. New cross-linked peptide-sugar compounds were identified and found to impact the formation of pyrazines. The results of this study may help in the preparation of thermal reaction flavors using enzymatically hydrolyzed vegetable/animal proteins, which contain a considerable amount of peptides, as one of the major reactants. © 2018 Institute of Food Technologists®.

Optimization of Maillard Reaction between Glucosamine and Other Precursors by Measuring Browning with a Spectrophotometer.

PubMed

Ogutu, Benrick; Kim, Ye-Joo; Kim, Dae-Wook; Oh, Sang-Chul; Hong, Dong-Lee; Lee, Yang-Bong

2017-09-01

The individual Maillard reactions of glucose, glucosamine, cyclohexylamine, and benzylamine were studied at a fixed temperature of 120°C under different durations by monitoring the absorbance of the final products at 425 nm. Glucosamine was the most individually reactive compound, whereas the reactions of glucose, cyclohexylamine, and benzylamine were not significantly different from each other. Maillard reactions of reaction mixtures consisting of glucosamine-cyclohexylamine, glucosamine-benzylamine, glucose-cyclohexylamine, and glucose-benzylamine were also studied using different concentration ratios under different durations at a fixed temperature of 120°C and pH 9. Maillard reactions in the pairs involving glucosamine were observed to be more intense than those of the pairs involving glucose. Finally, with respect to the concentration ratios, it was observed that in most instances, optimal activity was realized, when the reaction mixtures were in the ratio of 1:1.

Interface-related attributes of the Maillard reaction-born glycoproteins.

PubMed

Karbasi, Mehri; Madadlou, Ashkan

2017-01-19

Interfacial behavior of proteins which is a chief parameter to their emulsifying and foaming properties can be tailored through the Maillard reaction. The reaction can increase protein solubility at isoelectric point and ought to be controlled for example by high pressure processing to suppress melanoidins formation. Branched and long saccharides bring considerable steric hindrance which is associated with their site of conjugation to proteins. Conjugation with high molecular weight polysaccharides (such as 440 kDa dextran) may indeed increase the thickness of globular proteins interfacial film up to approximately 25 nm. However, an overly long saccharide can shield protein charge and slow down the electrophoretic mobility of conjugate. Maillard conjugation may decrease the diffusion rate of proteins to interface, allowing further unfolding at interface. As well, it can increase desorption iteration of proteins from interface. In addition to tempering proteins adsorption to interface, Maillard conjugation influences the rheology of protein membranes. Oligosaccharides (especially at higher glycation degrees) decrease the elastic modulus and Huggins constant of protein film; whereas, monosaccharides yield a more elastic interface. Accordingly, glycation of random coil proteins has been exploited to stiffen the corresponding interfacial membrane. Partial hydrolysis of proteins accompanied with anti-solvent-triggered nanoparticulation either before or after conjugation is a feasible way to enhance their emulsifying activity.

New functionalities of Maillard reaction products as emulsifiers and encapsulating agents, and the processing parameters: a brief review.

PubMed

Lee, Yee-Ying; Tang, Teck-Kim; Phuah, Eng-Tong; Alitheen, Noorjahan Banu Mohamed; Tan, Chin-Ping; Lai, Oi-Ming

2017-03-01

Non-enzymatic browning has been a wide and interesting research area in the food industry, ranging from the complexity of the reaction to its applications in the food industry as well as its ever-debatable health effects. This review provides a new perspective to the Maillard reaction apart from its ubiquitous function in enhancing food flavour, taste and appearance. It focuses on the recent application of Maillard reaction products as an inexpensive and excellent source of emulsifiers as well as superior encapsulating matrices for the entrapment of bioactive compounds. Additionally, it will also discuss the latest approaches employed to perform the Maillard reaction as well as several important reaction parameters that need to be taken into consideration when conducting the Maillard reaction. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Evolution of the Maillard Reaction in Glutamine or Arginine-Dextrinomaltose Model Systems.

PubMed

Pastoriza, Silvia; Rufián-Henares, José Ángel; García-Villanova, Belén; Guerra-Hernández, Eduardo

2016-12-07

Enteral formulas are foods designed for medical uses to feed patients who are unable to eat normally. They are prepared by mixing proteins, amino acids, carbohydrates and fats and submitted to sterilization. During thermal treatment, the Maillard reaction takes place through the reaction of animo acids with reducing sugars. Thus, although glutamine and arginine are usually added to improve the nutritional value of enteral formulas, their final concentration may vary. Thus, in the present paper the early, intermediate, and advanced states of the Maillard reaction were studied in model systems by measuring loss of free amino acids through the decrease of fluorescence intensity with o -phtaldialdehyde (OPA), 5-Hydroximethylfurfural (HMF), furfural, glucosylisomaltol, fluorescence, and absorbance at 420 nm. The systems were prepared by mixing glutamine or arginine with dextrinomaltose (similar ingredients to those used in special enteral formula), and heated at 100 °C, 120 °C and 140 °C for 0 to 30 min. The recorded changes in the concentration of furanic compounds was only useful for longer heating times of high temperatures, while absorbance and fluorescence measurements were useful in all the assayed conditions. In addition, easiness and sensitivity of absorbance and fluorescence make them useful techniques that could be implemented as indicators for monitoring the manufacture of special enteral formulas. Glucosylisomaltol is a useful indicator to monitor the manufacture of glutamine-enriched enteral formulas.

Mutagenicity of heated sugar-casein systems: effect of the Maillard reaction.

PubMed

Brands, C M; Alink, G M; van Boekel, M A; Jongen, W M

2000-06-01

The formation of mutagens after the heating of sugar-casein model systems at 120 degrees C was examined by the Ames test, using Salmonella typhimurium strain TA100. Several sugars (glucose, fructose, galactose, tagatose, lactose, and lactulose) were compared in their mutagenicities. Mutagenicity could be fully ascribed to Maillard reaction products and strongly varied with the kind of sugar. The differences in mutagenicity among the sugar-casein systems were caused by a difference in reaction rate and a difference in reaction mechanism. Sugars with a comparable reaction mechanism (glucose and galactose) showed a higher mutagenic activity corresponding with a higher Maillard reactivity. Disaccharides showed no mutagenic activity (lactose) or a lower mutagenic activity (lactulose) than their corresponding monosaccharides. Ketose sugars (fructose and tagatose) showed a remarkably higher mutagenicity compared with their aldose isomers (glucose and galactose), which was due to a difference in reaction mechanism.

Preventive effect of fermented Maillard reaction products from milk proteins in cardiovascular health.

PubMed

Oh, N S; Kwon, H S; Lee, H A; Joung, J Y; Lee, J Y; Lee, K B; Shin, Y K; Baick, S C; Park, M R; Kim, Y; Lee, K W; Kim, S H

2014-01-01

The aim of this study was to determine the dual effect of Maillard reaction and fermentation on the preventive cardiovascular effects of milk proteins. Maillard reaction products (MRP) were prepared from the reaction between milk proteins, such as whey protein concentrates (WPC) and sodium caseinate (SC), and lactose. The hydrolysates of MRP were obtained from fermentation by lactic acid bacteria (LAB; i.e., Lactobacillus gasseri H10, L. gasseri H11, Lactobacillus fermentum H4, and L. fermentum H9, where human-isolated strains were designated H1 to H15), which had excellent proteolytic and 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activities (>20%). The antioxidant activity of MRP was greater than that of intact proteins in assays of the reaction with 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) diammonium salt and trivalent ferric ions; moreover, the effect of MRP was synergistically improved by fermentation. The Maillard reaction dramatically increased the level of antithrombotic activity and 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR) inhibitory effect of milk proteins, but did not change the level of activity for micellar cholesterol solubility. Furthermore, specific biological properties were enhanced by fermentation. Lactobacillus gasseri H11 demonstrated the greatest activity for thrombin and HMGR inhibition in Maillard-reacted WPC, by 42 and 33%, respectively, whereas hydrolysates of Maillard-reacted SC fermented by L. fermentum H9 demonstrated the highest reduction rate for micellar cholesterol solubility, at 52%. In addition, the small compounds that were likely released by fermentation of MRP were identified by size-exclusion chromatography. Therefore, MRP and hydrolysates of fermented MRP could be used to reduce cardiovascular risks. Copyright © 2014 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

A novel thiamine-derived pigment, pyrizepine, formed by the Maillard reaction.

PubMed

Igoshi, Asuka; Noda, Kyoko; Murata, Masatsune

2018-04-26

To find a Maillard pigment derived from thiamine, a solution containing glucose and thiamine was heated and analyzed with high-performance liquid chromatography equipped with diode-array detection. As a result, a unique peak showing an absorption maximum at 380 nm was detected. This peak was then isolated from a reaction solution containing glucose, lysine and thiamine, and was identified as 1-(2-methyl-6,9-dihydro-5H-pyrimido[4,5-e][1,4]diazepin-7-yl)ethan-1-one using instrumental analyses. This compound, named pyrizepine, was a novel yellow pigment having a fused ring consisting of pyrimidine and diazepine. Pyrizepine was a major low-molecular-weight pigment in the reaction solution. The structure suggests that pyrizepine is formed by condensation reaction between a degradation product of thiamine and a tetrosone derivative formed from glucose by the Maillard reaction.

A perspective on the Maillard reaction and the analysis of protein glycation by mass spectrometry: probing the pathogenesis of chronic disease.

PubMed

Zhang, Qibin; Ames, Jennifer M; Smith, Richard D; Baynes, John W; Metz, Thomas O

2009-02-01

The Maillard reaction, starting from the glycation of protein and progressing to the formation of advanced glycation end-products (AGEs), is implicated in the development of complications of diabetes mellitus, as well as in the pathogenesis of cardiovascular, renal, and neurodegenerative diseases. In this perspective review, we provide an overview on the relevance of the Maillard reaction in the pathogenesis of chronic disease and discuss traditional approaches and recent developments in the analysis of glycated proteins by mass spectrometry. We propose that proteomics approaches, particularly bottom-up proteomics, will play a significant role in analyses of clinical samples leading to the identification of new markers of disease development and progression.

Optimization of Maillard Reaction between Glucosamine and Other Precursors by Measuring Browning with a Spectrophotometer

PubMed Central

Ogutu, Benrick; Kim, Ye-Joo; Kim, Dae-Wook; Oh, Sang-Chul; Hong, Dong-Lee; Lee, Yang-Bong

2017-01-01

The individual Maillard reactions of glucose, glucosamine, cyclohexylamine, and benzylamine were studied at a fixed temperature of 120°C under different durations by monitoring the absorbance of the final products at 425 nm. Glucosamine was the most individually reactive compound, whereas the reactions of glucose, cyclohexylamine, and benzylamine were not significantly different from each other. Maillard reactions of reaction mixtures consisting of glucosamine-cyclohexylamine, glucosamine-benzylamine, glucose-cyclohexylamine, and glucose-benzylamine were also studied using different concentration ratios under different durations at a fixed temperature of 120°C and pH 9. Maillard reactions in the pairs involving glucosamine were observed to be more intense than those of the pairs involving glucose. Finally, with respect to the concentration ratios, it was observed that in most instances, optimal activity was realized, when the reaction mixtures were in the ratio of 1:1. PMID:29043219

Food Processing: The Influence of the Maillard Reaction on Immunogenicity and Allergenicity of Food Proteins

PubMed Central

Teodorowicz, Malgorzata; van Neerven, Joost

2017-01-01

The majority of foods that are consumed in our developed society have been processed. Processing promotes a non-enzymatic reaction between proteins and sugars, the Maillard reaction (MR). Maillard reaction products (MRPs) contribute to the taste, smell and color of many food products, and thus influence consumers’ choices. However, in recent years, MRPs have been linked to the increasing prevalence of diet- and inflammation-related non-communicable diseases including food allergy. Although during the last years a better understanding of immunogenicity of MRPs has been achieved, still only little is known about the structural/chemical characteristics predisposing MRPs to interact with antigen presenting cells (APCs). This report provides a comprehensive review of recent studies on the influence of the Maillard reaction on the immunogenicity and allergenicity of food proteins. PMID:28777346

Food Processing: The Influence of the Maillard Reaction on Immunogenicity and Allergenicity of Food Proteins.

PubMed

Teodorowicz, Malgorzata; van Neerven, Joost; Savelkoul, Huub

2017-08-04

The majority of foods that are consumed in our developed society have been processed. Processing promotes a non-enzymatic reaction between proteins and sugars, the Maillard reaction (MR). Maillard reaction products (MRPs) contribute to the taste, smell and color of many food products, and thus influence consumers' choices. However, in recent years, MRPs have been linked to the increasing prevalence of diet- and inflammation-related non-communicable diseases including food allergy. Although during the last years a better understanding of immunogenicity of MRPs has been achieved, still only little is known about the structural/chemical characteristics predisposing MRPs to interact with antigen presenting cells (APCs). This report provides a comprehensive review of recent studies on the influence of the Maillard reaction on the immunogenicity and allergenicity of food proteins.

Investigation of the Maillard Reaction between Polysaccharides and Proteins from Longan Pulp and the Improvement in Activities.

PubMed

Han, Miao-Miao; Yi, Yang; Wang, Hong-Xun; Huang, Fei

2017-06-05

The purpose of this study was to investigate the Maillard reaction between polysaccharides and proteins from longan pulp and the effects of reaction on their in vitro activities. The polysaccharide-protein mixtures of fresh longan pulp (LPPMs) were co-prepared by an alkali extraction-acid precipitation method. They were then dry-heated under controlled conditions for monitoring the characterization of the Maillard reaction by the measurement of the free amino group content, ultraviolet-visible spectrum, Fourier transform infrared spectrum and molecular weight distribution. All the physicochemical analyses indicated the development of the Maillard reaction between polysaccharides and proteins. The in vitro activity evaluation indicated that the Maillard reaction could effectively enhance the antioxidant, antitumor and immunostimulating activities of LPPMs. The enhancement of 1,1-diphenyl-2-picrylhydrazyl radical scavenging activity and ferric reducing antioxidant power displayed both a positive correlation with the reaction time ( p < 0.05). LPPMs dry-heated for three days obtained relatively strong inhibitory activity against HepG2 cells and SGC7901 cells, as well as strong immunostimulating effects on the nitric oxide production and tumor necrosis factor α secretion of macrophages. Maillard-type intermacromolecular interaction is suggested to be an effective and controllable method for improving the functional activities of polysaccharides and proteins from longan pulp.

Transglycosylation reactions, a main mechanism of phenolics incorporation in coffee melanoidins: Inhibition by Maillard reaction.

PubMed

Moreira, Ana S P; Nunes, Fernando M; Simões, Cristiana; Maciel, Elisabete; Domingues, Pedro; Domingues, M Rosário M; Coimbra, Manuel A

2017-07-15

Under roasting conditions, polysaccharides depolymerize and also are able to polymerize, forming new polymers through non-enzymatic transglycosylation reactions (TGRs). TGRs can also occur between carbohydrates and aglycones, such as the phenolic compounds present in daily consumed foods like coffee. In this study, glycosidically-linked phenolic compounds were quantified in coffee melanoidins, the polymeric nitrogenous brown-colored compounds formed during roasting, defined as end-products of Maillard reaction. One third of the phenolics present were in glycosidically-linked form. In addition, the roasting of solid-state mixtures mimicking coffee beans composition allowed the conclusion that proteins play a regulatory role in TGRs extension and, consequently, modulate melanoidins composition. Overall, the results obtained showed that TGRs are a main mechanism of phenolics incorporation in melanoidins and are inhibited by amino groups through Maillard reaction. Copyright © 2017 Elsevier Ltd. All rights reserved.

Investigation of Possible Maillard Reaction Between Acyclovir and Dextrose upon Dilution Prior to Parenteral Administration.

PubMed

Siahi Shadbad, Mohammad Reza; Ghaderi, Faranak; Hatami, Leila; Monajjemzadeh, Farnaz

2016-12-01

In this study the stability of parenteral acyclovir (ACV) when diluted in dextrose (DEX) as large volume intravenous fluid preparation (LVIF) was evaluated and the possible Maillard reaction adducts were monitored in the recommended infusion time. Different physicochemical methods were used to evaluate the Maillard reaction of dextrose with ACV to track the reaction in real infusion condition. Other large volume intravenous fluids were checked regarding the diluted drug stability profile. Differential scanning calorimetry (DSC), Fourier transform infrared spectroscopy (FTIR), and mass data proved the reaction of glucose with dextrose. A Maillard-specific high performance liquid chromatography (HPLC) method was used to track the reaction in real infusion condition in vitro. The nucleophilic reaction occurred in diluted parenteral preparations of acyclovir in 5% dextrose solutions. The best diluent solution was also selected as sodium chloride and introduced based on drug stability and also its adsorption onto different infusion sets (PVC or non PVC) to provide an acceptable administration protocol in clinical practices. Although, the Maillard reaction was proved and successfully tracked in diluted solutions, and the level of drug loss when diluted in dextrose was reported to be between 0.27 up to 1.03% of the initial content. There was no drug adsorption to common infusion sets. The best diluent for parenteral acyclovir is sodium chloride large volume intravenous fluid.

Food Processing and Maillard Reaction Products: Effect on Human Health and Nutrition

PubMed Central

Tamanna, Nahid; Mahmood, Niaz

2015-01-01

Maillard reaction produces flavour and aroma during cooking process; and it is used almost everywhere from the baking industry to our day to day life to make food tasty. It is often called nonenzymatic browning reaction since it takes place in the absence of enzyme. When foods are being processed or cooked at high temperature, chemical reaction between amino acids and reducing sugars leads to the formation of Maillard reaction products (MRPs). Depending on the way the food is being processed, both beneficial and toxic MRPs can be produced. Therefore, there is a need to understand the different types of MRPs and their positive or negative health effects. In this review we have summarized how food processing effects MRP formation in some of the very common foods. PMID:26904661

Identification of Maillard reaction induced chemical modifications on Ara h 1

USDA-ARS?s Scientific Manuscript database

The Maillard reaction is a non-enzymatic glycation reaction between proteins and reducing sugars that can modify nut allergens during thermal processing. These modifications can alter the structural and immunological properties of these allergens, and may result in increased IgE binding. Here, we ...

Maillard-reaction-induced modification and aggregation of proteins and hardening of texture in protein bar model systems.

PubMed

Zhou, Peng; Guo, Mufan; Liu, Dasong; Liu, Xiaoming; Labuza, Teodore P

2013-03-01

The hardening of high-protein bars causes problems in their acceptability to consumers. The objective of this study was to determine the progress of the Maillard reaction in model systems of high-protein nutritional bars containing reducing sugars, and to illustrate the influences of the Maillard reaction on the modification and aggregation of proteins and the hardening of bar matrices during storage. The progress of the Maillard reaction, glycation, and aggregation of proteins, and textural changes in bar matrices were investigated during storage at 25, 35, and 45 °C. The initial development of the Maillard reaction caused little changes in hardness; however, further storage resulted in dramatic modification of protein with formation of high-molecular-weight polymers, resulting in the hardening in texture. The replacement of reducing sugars with nonreducing ingredients such as sugar alcohols in the formula minimized the changes in texture. The hardening of high-protein bars causes problems in their acceptability to consumers. Maillard reaction is one of the mechanisms contributing to the hardening of bar matrix, particularly for the late stage of storage. The replacement of reducing sugars with nonreducing ingredients such as sugar alcohols in the formula will minimize the changes in texture. © 2013 Institute of Food Technologists®

Accumulation of Maillard reaction products in skin collagen in diabetes and aging.

PubMed Central

Dyer, D G; Dunn, J A; Thorpe, S R; Bailie, K E; Lyons, T J; McCance, D R; Baynes, J W

1993-01-01

To investigate the contribution of glycation and oxidation reactions to the modification of insoluble collagen in aging and diabetes, Maillard reaction products were measured in skin collagen from 39 type 1 diabetic patients and 52 nondiabetic control subjects. Compounds studied included fructoselysine (FL), the initial glycation product, and the glycoxidation products, N epsilon-(carboxymethyl) lysine (CML) and pentosidine, formed during later Maillard reactions. Collagen-linked fluorescence was also studied. In nondiabetic subjects, glycation of collagen (FL content) increased only 33% between 20 and 85 yr of age. In contrast, CML, pentosidine and fluorescence increased five-fold, correlating strongly with age. In diabetic patients, collagen FL was increased threefold compared with nondiabetic subjects, correlating strongly with glycated hemoglobin but not with age. Collagen CML, pentosidine and fluorescence were increased up to twofold in diabetic compared with control patients: this could be explained by the increase in glycation alone, without invoking increased oxidative stress. There were strong correlations among CML, pentosidine and fluorescence in both groups, providing evidence for age-dependent chemical modification of collagen via the Maillard reaction, and acceleration of this process in diabetes. These results support the description of diabetes as a disease characterized by accelerated chemical aging of long-lived tissue proteins. PMID:8514858

A Perspective on the Maillard Reaction and the Analysis of Protein Glycation by Mass Spectrometry: Probing the Pathogenesis of Chronic Disease

PubMed Central

Zhang, Qibin; Ames, Jennifer M.; Smith, Richard D.; Baynes, John W.; Metz, Thomas O.

2009-01-01

The Maillard reaction, starting from the glycation of protein and progressing to the formation of advanced glycation end-products (AGEs), is implicated in the development of complications of diabetes mellitus, as well as in the pathogenesis of cardiovascular, renal, and neurodegenerative diseases. In this perspective review, we provide an overview on the relevance of the Maillard reaction in the pathogenesis of chronic disease and discuss traditional approaches and recent developments in the analysis of glycated proteins by mass spectrometry. We propose that proteomics approaches, particularly bottom-up proteomics, will play a significant role in analyses of clinical samples leading to the identification of new markers of disease development and progression. PMID:19093874

A Perspective on the Maillard Reaction and the Analysis of Protein Glycation by Mass Spectrometry: Probing the Pathogenesis of Chronic Disease

DOE Office of Scientific and Technical Information (OSTI.GOV)

Zhang, Qibin; Ames, Jennifer M.; Smith, Richard D.

2008-12-18

The Maillard reaction, starting from the glycation of protein and progressing to the formation of advanced glycation end-products (AGEs), is implicated in the development of complications of diabetes mellitus, as well as in the pathogenesis of cardiovascular, renal, and neurodegenerative diseases. In this perspective review, we provide on overview on the relevance of the Maillard reaction in the pathogenesis of chronic disease and discuss traditional approaches and recent developments in the analysis of glycated proteins by mass spectrometry. We propose that proteomics approaches, particularly bottom-up proteomics, will play a significant role in analyses of clinical samples leading to the identificationmore » of new markers of disease development and progression.« less

Contribution of crosslinking products in the flavour enhancer processing: the new concept of Maillard peptide in sensory characteristics of Maillard reaction systems.

PubMed

Karangwa, Eric; Murekatete, Nicole; Habimana, Jean de Dieu; Masamba, Kingsley; Duhoranimana, Emmanuel; Muhoza, Bertrand; Zhang, Xiaoming

2016-06-01

In this study, the flavour-enhancing properties of the Maillard reaction products (MRPs) for different systems consisted of different peptides (sunflower, SFP; corn, CP and soyabean SP) with, xylose and cysteine were investigated. Maillard systems from peptides of sunflower, corn and soyabean with xylose and cysteine were designated as PXC, MCP and MSP, respectively. The Maillard systems were prepared at pH of 7.4 using temperature of 120C for 2 h. Results showed that all systems were significantly different in all sensory attributes. The highest scores for mouthfulness and continuity were observed for MCP with the lowest peptides distribution between 1000 and 5000 Da, known as Maillard peptide. This revealed that the MCP with the lowest Maillard peptide content had the strongest "Kokumi" effect compared to the other MRPsand demonstrated that "kokumi effect" of MRPs was contributed by not only the "Maillard peptide" defined by the molecular weight (1000-5000 Da). Results on sensory evaluation after fractionation of PXC followed by enzymatic hydrolysis showed no significant differences between PXC, P-PXC and their hydrolysates. This observation therefore confirmed that the presence of other contributors attributed to the "Kokumi" effect rather than the Maillard peptide. It can be deduced that the unhydrolyzed crosslinking products might have contributed to the "Kokumi" effect of MRPs. The structures of four probable crosslinking compounds were proposed and the findings have provided new insights in the sensory characteristics of xylose, cysteine and sunflower peptide MRPs.

Effects of Maillard reaction on allergenicity of buckwheat allergen Fag t 3 during thermal processing.

PubMed

Yang, Zhen-Huang; Li, Chen; Li, Yu-Ying; Wang, Zhuan-Hua

2013-04-01

Fag t 3 is a major allergenic protein in tartary buckwheat. The Maillard reaction commonly occurs in food processing, but few studies have been conducted on the influence of thermal processing on the allergenic potential of buckwheat allergen. The aim of the present study was to investigate the effects of autologous plant polysaccharides on the immunoreactivity of buckwheat Fag t 3 (11S globulin) following the Maillard reaction. Fag t 3 and crude polysaccharides were prepared from tartary buckwheat (Fagopyrum tataricum) flour. After heating, the polysaccharides were covalently linked to Fag t 3 via a Maillard reaction, and the IgE/IgG-binding properties of Fag t 3 decreased dramatically, with significant changes also being observed in the electrophoretic mobility, secondary structure and solubility of the glycated Fag t 3. The great influence of glycation on IgE/IgG binding to Fag t 3 was correlated with a significant change in the structure and epitopes of the allergenic protein. These data indicated that conjugation of polysaccharides to Fag t 3 markedly reduced the allergen's immunoreactivity. Glycation that occurs via the Maillard reaction during the processing of buckwheat food may be an efficient method to reduce Fag t 3 allergenicity. © 2012 Society of Chemical Industry.

One-step simultaneous differential scanning calorimetry-FTIR microspectroscopy to quickly detect continuous pathways in the solid-state glucose/asparagine Maillard reaction.

PubMed

Hwang, Deng-Fwu; Hsieh, Tzu-Feng; Lin, Shan-Yang

2013-01-01

The stepwise reaction pathway of the solid-state Maillard reaction between glucose (Glc) and asparagine (Asn) was investigated using simultaneous differential scanning calorimetry (DSC)-FTIR microspectroscopy. The color change and FTIR spectra of Glc-Asn physical mixtures (molar ratio = 1:1) preheated to different temperatures followed by cooling were also examined. The successive reaction products such as Schiff base intermediate, Amadori product, and decarboxylated Amadori product in the solid-state Glc-Asn Maillard reaction were first simultaneously evidenced by this unique DSC-FTIR microspectroscopy. The color changed from white to yellow-brown to dark brown, and appearance of new IR peaks confirmed the formation of Maillard reaction products. The present study clearly indicates that this unique DSC-FTIR technique not only accelerates but also detects precursors and products of the Maillard reaction in real time.

Effects of odor generated from the glycine/glucose Maillard reaction on human mood and brainwaves.

PubMed

Zhou, Lanxi; Ohata, Motoko; Arihara, Keizo

2016-06-15

Effects of the odor generated from the glycine/glucose Maillard reaction on human mood and brainwaves were investigated in the present study. Equimolar solutions of glucose and glycine were adjusted to pH 7 and pH 9 and heated at 90 °C for 30 min. The odor generated from the glycine/glucose Maillard reaction significantly decreased negative moods. Its effects on brainwaves differed according to pH; alpha brainwave distribution was increased after inhalation of the odor generated at pH 7, whereas it was decreased by the odor generated at pH 9. The effects on mood and brainwaves were also measured after inhalation of model solutions, which comprised of potent odorants determined by aroma extract dilution analysis (AEDA), and the results were similar to those obtained with the Maillard reaction samples. Therefore, odors constructed by potent odorants could influence human mood and brainwaves. Among all potent odorants, 2,3-dimethylpyrazine and 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF) were identified as the strongest, and high pH values resulted in higher yields of these odorants. Furthermore, DMHF was identified as the putative agent responsible for the decrease in alpha brainwave distribution after smelling the pH-9 Maillard reaction sample since higher concentrations of DMHF resulted in a similar effect.

High-intensity ultrasound production of Maillard reaction flavor compounds in a cysteine-xylose model system.

PubMed

Ong, Olivia X H; Seow, Yi-Xin; Ong, Peter K C; Zhou, Weibiao

2015-09-01

Application of high intensity ultrasound has shown potential in the production of Maillard reaction odor-active flavor compounds in model systems. The impact of initial pH, sonication duration, and ultrasound intensity on the production of Maillard reaction products (MRPs) by ultrasound processing in a cysteine-xylose model system were evaluated using Response Surface Methodology (RSM) with a modified mathematical model. Generation of selected MRPs, 2-methylthiophene and tetramethyl pyrazine, was optimal at an initial pH of 6.00, accompanied with 78.1 min of processing at an ultrasound intensity of 19.8 W cm(-2). However, identification of volatiles using gas chromatography-mass spectrometry (GC/MS) revealed that ultrasound-assisted Maillard reactions generated fewer sulfur-containing volatile flavor compounds as compared to conventional heat treatment of the model system. Likely reasons for this difference in flavor profile include the expulsion of H2S due to ultrasonic degassing and inefficient transmission of ultrasonic energy. Copyright © 2015 Elsevier B.V. All rights reserved.

Modifications of hemoglobin and myoglobin by Maillard reaction products (MRPs).

PubMed

Ioannou, Aristos; Varotsis, Constantinos

2017-01-01

High performance liquid chromatography (HPLC) coupled with a Fraction Collector was employed to isolate Maillard reaction products (MRPs) formed in model systems comprising of asparagine and monosaccharides in the 60-180°C range. The primary MRP which is detected at 60°C is important for Acrylamide content and color/aroma development in foods and also in the field of food biotechnology for controlling the extent of the Maillard reaction with temperature. The discrete fractions of the reaction products were reacted with Hemoglobin (Hb) and Myoglobin (Mb) at physiological conditions and the reaction adducts were monitored by UV-vis and Attenuated Total Reflection-Fourier transform infrared (FTIR) spectrophotometry. The UV-vis kinetic profiles revealed the formation of a Soret transition characteristic of a low-spin six-coordinated species and the ATR-FTIR spectrum of the Hb-MRP and Mb-MRP fractions showed modifications in the protein Amide I and II vibrations. The UV-vis and the FTIR spectra of the Hb-MRPs indicate that the six-coordinated species is a hemichrome in which the distal E7 Histidine is coordinated to the heme Fe and blocks irreversibly the ligand binding site. Although the Mb-MRPs complex is a six-coordinated species, the 1608 cm-1 FTIR band characteristic of a hemichrome was not observed.

Effect of Maillard reaction products on the physical and antimicrobial properties of edible films based on ε-polylysine and chitosan.

PubMed

Wang, Yingying; Liu, Fuguo; Liang, Chunxuan; Yuan, Fang; Gao, Yanxiang

2014-11-01

Edible films based on Maillard reaction products (MRPs) of ε-polylysine and chitosan, without the use of any plasticiser, were prepared by solution casting. The effect of Maillard reaction parameters (reaction time and the ratio of polylysine/chitosan) of ε-polylysine and chitosan on the structure, moisture content, water solubility, total colour difference and mechanical properties of edible films formed by MRPs were systematically evaluated. Scanning electron microscopy confirmed that edible films prepared by the MRPs of ε-polylysine and chitosan through the Maillard reaction exhibited a more compact and dense structure than those from the mixture of biopolymers without the presence of MRPs. The tensile strength and % elongation values of films from the mixture were decreased significantly with the rise of ε-polylysine (P < 0.05). The moisture content of the films was not significantly affected by Maillard reaction, whereas water solubility was decreased and total colour difference was increased significantly (P < 0.05) with the extension of Maillard reaction time. In addition, antimicrobial activity of chitosan films against E. coli and S. aureus. could be achieved by incorporating ε-polylysine into chitosan. These films can ensure food quality and safety, especially for coating highly perishable foods, such as meat products. © 2014 Society of Chemical Industry. © 2014 Society of Chemical Industry.

Evaluation of the Flavor Contribution of Products of the Maillard Reaction

DTIC Science & Technology

the Maillard - type reaction between the products of autoxidized polyunsaturated fatty acids and free amino groups of phospholipids and within meat...intermolecular browning-type reaction with free amino groups, polymerization, etc., are liable to occur. Changes in these labile substances are known...proteins, and between the free amino groups of phospholipids and the monosaccharides present in meat. The reaction was elucidated and its products characterized and evaluated for its contribution to meat flavor.

Maillard reaction products as antimicrobial components for packaging films.

PubMed

Hauser, Carolin; Müller, Ulla; Sauer, Tanja; Augner, Kerstin; Pischetsrieder, Monika

2014-02-15

Active packaging foils with incorporated antimicrobial agents release the active ingredient during food storage. Maillard reaction products (MRPs) show antimicrobial activity that is at least partially mediated by H2O2. De novo generation of H2O2 by an MRP fraction, extracted from a ribose/lysine Maillard reaction mixture by 85% ethanol, was monitored at three concentrations (1.6, 16.1, and 32.3g/L) and three temperatures (4, 25, and 37 °C) between 0 and 96 h, reaching a maximum of 335 μM H2O2 (32.3g/L, 37 °C, 96 h). The active MRP fraction (16.1g/L) completely inhibited the growth of Escherichia coli for 24h and was therefore incorporated in a polyvinyl acetate-based lacquer and dispersed onto a low-density polyethylene film. The coated film generated about 100 μM H2O2 and resulted in a log-reduction of >5 log-cycles against E. coli. Thus, MRPs can be considered as active ingredients for antimicrobial packaging materials. Copyright © 2013 Elsevier Ltd. All rights reserved.

Vitamin C mediates chemical aging of lens crystallins by the Maillard reaction in a humanized mouse model

PubMed Central

Fan, Xingjun; Reneker, Lixing W.; Obrenovich, Mark E.; Strauch, Christopher; Cheng, Rongzhu; Jarvis, Simon M.; Ortwerth, Beryl J.; Monnier, Vincent M.

2006-01-01

Senile cataracts are associated with progressive oxidation, fragmentation, cross-linking, insolubilization, and yellow pigmentation of lens crystallins. We hypothesized that the Maillard reaction, which leads browning and aroma development during the baking of foods, would occur between the lens proteins and the highly reactive oxidation products of vitamin C. To test this hypothesis, we engineered a mouse that selectively overexpresses the human vitamin C transporter SVCT2 in the lens. Consequently, lenticular levels of vitamin C and its oxidation products were 5- to 15-fold elevated, resulting in a highly compressed aging process and accelerated formation of several protein-bound advanced Maillard reaction products identical with those of aging human lens proteins. These data strongly implicate vitamin C in lens crystallin aging and may serve as a model for protein aging in other tissues particularly rich in vitamin C, such as the hippocampal neurons and the adrenal gland. The hSVCT2 mouse is expected to facilitate the search for drugs that inhibit damage by vitamin C oxidation products. PMID:17075057

Contribution of Histidine and Lysine to the Generation of Volatile Compounds in Jinhua Ham Exposed to Ripening Conditions Via Maillard Reaction.

PubMed

Zhu, Chao-Zhi; Zhao, Jing-Li; Tian, Wei; Liu, Yan-Xia; Li, Miao-Yun; Zhao, Gai-Ming

2018-01-01

To evaluate the role of Maillard reactions in the generation of flavor compounds in Jinhua ham, the reactions of glucose and ethanal with histidine and lysine, respectively, were studied by simulating the ripening conditions of Jinhua ham. The volatile products produced were analyzed using solid phase microextraction-gas chromatography/mass spectrometry. The results showed that 8 volatile compounds were generated by the reaction of glucose and histidine and 10 volatile compounds were generated by the reaction of glucose and lysine. Reactions of ethanal with lysine and with histidine both generated 31 volatile compounds that contributed to the flavor of Jinhua ham. This indicates that histidine and lysine related to Maillard reactions possibly play important roles in the generation of the unique flavor compounds in Jinhua ham. This research demonstrates that free amino acids participate in the generation of volatile compounds from Jinhua ham via the Maillard reaction and provides a basic mechanism to explain flavor formation in Jinhua ham. Jinhua ham is a well-known traditional Chinese dry-cured meat product. However, the formation of the compounds comprising its special flavor is not well understood. Our results indicate that Maillard reactions occur in Jinhua ham under ripening conditions. This work illustrates the contribution of Maillard reactions to the flavor of Jinhua ham. © 2017 Institute of Food Technologists®.

Forty years of furosine - forty years of using Maillard reaction products as indicators of the nutritional quality of foods.

PubMed

Erbersdobler, Helmut F; Somoza, Veronika

2007-04-01

The Maillard reaction products (MRPs) most widely used as markers of the nutritional quality of foods are furosine, N(epsilon)-carboxymethyllysine (CML), hydroxymethylfurfural, pyrraline, pentosidine and pronyl-lysine. One of the MRPs identified first was furosine, which was quantified in foods 40 years ago as a chemical indicator of the Amadori compound N(epsilon)-fructoselysine. Since then, furosine has gained broad attention by food chemists and biomedical researchers, as its formation upon heat treatment is well characterised. Moreover, it represents the Amadori products from early Maillard reactions in which amino acids react with reducing carbohydrates, resulting in a loss of their availability. This is of importance for the essential amino acid lysine, which is also the limiting amino acid in many proteins. In order to evaluate the nutritional quality of a protein, the concomitant analysis of free - and nutritionally available - lysine and the amount of lysine reacted to form the respective MRP is essential, even for mildly processed foods. The other chemical markers of heat treatment such as CML, pyrraline, pentosidine or pronyl-lysine seem to be useful markers of the advanced stages of Maillard reactions. Compared to the conditions in which furosine is formed, these compounds are generated under more severe conditions of heat treatment. However, the concentrations analysed are significantly lower than those of furosine. Therefore, the nutritional evaluation of a food protein should include not only furosine, but also other chemical markers of heat treatment such as, for example, CML, pyrraline and pentosidine.

The Electronic Flux in Chemical Reactions. Insights on the Mechanism of the Maillard Reaction

NASA Astrophysics Data System (ADS)

Flores, Patricio; Gutiérrez-Oliva, Soledad; Herrera, Bárbara; Silva, Eduardo; Toro-Labbé, Alejandro

2007-11-01

The electronic transfer that occurs during a chemical process is analysed in term of a new concept, the electronic flux, that allows characterizing the regions along the reaction coordinate where electron transfer is actually taking place. The electron flux is quantified through the variation of the electronic chemical potential with respect to the reaction coordinate and is used, together with the reaction force, to shed light on reaction mechanism of the Schiff base formation in the Maillard reaction. By partitioning the reaction coordinate in regions in which different process might be taking place, electronic reordering associated to polarization and transfer has been identified and found to be localized at specific transition state regions where most bond forming and breaking occur.

Maillard reaction products of rice protein hydrolysates with mono-, oligo- and polysaccharides

USDA-ARS?s Scientific Manuscript database

Rice protein, a byproduct of rice syrup production, is abundant but, its lack of functionality prevents its wide use as a food ingredient. Maillard reaction products of (MRPs) hydrolysates from the limited hydrolysis of rice protein (LHRP) and various mono-, oligo- and polysaccharides were evaluat...

Controlling the Maillard reaction by reactant encapsulation: sodium chloride in cookies.

PubMed

Fiore, Alberto; Troise, Antonio Dario; Ataç Mogol, Burçe; Roullier, Victor; Gourdon, Anthony; El Mafadi Jian, Samira; Hamzalioğlu, Berat Aytül; Gökmen, Vural; Fogliano, Vincenzo

2012-10-31

Formation of Maillard reaction products (MRPs) including 5-hydroxymethylfurfural (HMF) and acrylamide has been an intensive area of research in recent decades. The presence of reactants such as sodium chloride may influence the Maillard reaction (MR) pathways through the dehydration of various key intermediates. The aim of this work was to test the potential of ingredient encapsulation to mitigate the MR by investigating the case of sodium chloride encapsulation on the HMF formation in cookies. Thirteen cookies were prepared with recipes containing free or encapsulated NaCl. Increasing NaCl concentration from 0 to 0.65% increases HMF concentration up to 75%, whereas in the presence of encapsulated NaCl the reduction of HMF varied from 18 to 61% due to the inhibition of sucrose pyrolytic decomposition and the fructofuranosyl cation formation. Data demonstrated that the more heat-resistant the lipid-based coating was, the more pronounced the reduction of HMF formation. The results showed that encapsulation represents a useful approach to prevent the formation of potentially harmful compounds in thermally processed foods.

Implications of the Maillard reaction on bovine alpha-lactalbumin and its proteolysis during in vitro infant digestion.

PubMed

Joubran, Yousef; Moscovici, Alice; Portmann, Reto; Lesmes, Uri

2017-06-21

This study investigated the functionality and digestibility of Maillard reaction products (MRPs) of alpha-lactalbumin (α-la), a major whey protein and component of infant formulas. The impact of different carbohydrates (glucose, galactose or galacto-oligosaccharides (GOS)) and heating duration was studied. SDS-PAGE, UV and color measurements monitored reaction extent, which varied between carbohydrates whereby galactose reacted more readily than glucose. Surface hydrophobicity and antioxidant capacity were found to be significantly (p < 0.05) higher following Maillard conjugation, with GOS-based MRPs elevating antioxidant capacity ∼50-fold compared to α-la. In addition, the digestive proteolysis of MRPs was evaluated using an infant in vitro gastro-duodenal model. SDS-PAGE analyses of digesta revealed Maillard conjugation generally increased α-la's susceptibility to proteolysis. Interestingly, GOS-based MRPs presented an optimization challenge, since heating for 12 h delayed proteolysis, while extended heating resulted in the highest susceptibility to proteolysis. Proteomic analyses further demonstrated the differences in enzymatic cleavage patterns and helped identify bioactive peptides rendered bioaccessible during the digestion of α-la or its MRPs. Bioinformatic mining of the proteomic data using PeptideRanker also gave rise to two potentially novel bioactive peptides, FQINNKIW and GINYWLAHKALCS. Finally, antioxidant capacity of luminal contents, measured by DPPH, revealed Maillard conjugation increased the antioxidant capacity of both gastric and duodenal digesta. Overall, this work draws a link between the Maillard reaction, digestive proteolysis and the bioaccessibility of bioactive peptides and antioxidant species in the infant alimentary canal. This could help rationally process infant formulas towards improved nutritional and extra-nutritional benefits.

Increase of rutin antioxidant activity by generating Maillard reaction products with lysine.

PubMed

Zhang, Ru; Zhang, Bian-Ling; He, Ting; Yi, Ting; Yang, Ji-Ping; He, Bin

2016-06-01

Rutin exists in medicinal herbs, fruits, vegetables, and a number of plant-derived sources. Dietary sources containing rutin are considered beneficial because of their potential protective roles in multiple diseases related to oxidative stresses. In the present study, the change and antioxidation activity of rutin in Maillard reaction with lysine through a heating process were investigated. There is release of glucose and rhamnose that interact with lysine to give Maillard reaction products (MRPs), while rutin is converted to less-polar quercetin and a small quantity of isoquercitrin. Because of their high cell-membrane permeability, the rutin-lysine MRPs increase the free radical-scavenging activity in HepG2 cells, showing cellular antioxidant activity against Cu(2+)-induced oxidative stress higher than that of rutin. Furthermore, the MRPs significantly increased the Cu/Zn SOD (superoxide dismutase) activity and Cu/Zn SOD gene expression of HepG2 cells, consequently enhancing antioxidation activity. Copyright © 2016 Elsevier Ltd. All rights reserved.

The browning value changes and spectral analysis on the Maillard reaction product from glucose and methionine model system

NASA Astrophysics Data System (ADS)

Al-Baarri, A. N.; Legowo, A. M.; Widayat

2018-01-01

D-glucose has been understood to provide the various effect on the reactivity in Maillard reaction resulting in the changes in physical performance of food product. Therefore this research was done to analyse physical appearance of Maillard reaction product made of D-glucose and methionine as a model system. The changes in browning value and spectral analysis model system were determined. The glucose-methionine model system was produced through the heating treatment at 50°C and RH 70% for 24 hours. The data were collected for every three hour using spectrophotometer. As result, browning value was elevated with the increase of heating time and remarkably high if compare to the D-glucose only. Furthermore, the spectral analysis showed that methionine turned the pattern of peak appearance. As conclusion, methionine raised the browning value and changed the pattern of spectral analysis in Maillard reaction model system.

The functional properties of chitosan-glucose-asparagine Maillard reaction products and mitigation of acrylamide formation by chitosans.

PubMed

Sung, Wen-Chieh; Chang, Yu-Wei; Chou, Yu-Hao; Hsiao, Hsin-I

2018-03-15

This research aims to clarify the interactions that occur in a food model system consisting of glucose, asparagine and chitosans. Low molecular weight chitosan exerted a potent inhibitory effect (46.8%) on acrylamide and Maillard reaction products (MRPs) (>52.6%), respectively. Compared to a previous study conducted using the fructose system, the novel findings of this research demonstrate that the formation of acrylamide and Maillard reaction products was lower with glucose than with fructose when they were used as reducing sugars in food model systems. Copyright © 2017 Elsevier Ltd. All rights reserved.

Effects of Maillard reaction on flavor and safety of Chinese traditional food: roast duck.

PubMed

Zhou, Yiming; Xie, Fan; Zhou, Xiaoli; Wang, Yuqiang; Tang, Wen; Xiao, Ying

2016-04-01

Roast duck is one kind of representative roast food whose flavor is mainly produced by the Maillard reaction. However, some potentially toxic compounds are generated in the thermal process and are a potential health risk. The aim of this work was to analyze the effects of the Maillard reaction on flavor and safety of a Chinese traditional food: roast duck. Ducks with different roasting times (0, 10, 20, 30, 40, 50 and 60 min) were analyzed. The 40 and 50 min roast ducks exhibited an acceptable degree of sensory attributes, but the 60 min roast duck showed the most abundant aroma compounds. Antioxidant activities were observed to increase with roasting, and the 60 min roast duck showed the highest antioxidant activities (1,1-diphenylpicryhydrazyl, 39.3 µmol Trolox g(-1) sample). The highest content of acrylamide (0.21 µg g(-1)) and 5-hydroxymethylfurfural (0.089 µg g(-1)) were detected in the 50 and 60 min roast duck extract, respectively. Furthermore, water extract from 60 min roast ducks manifested a higher lactose dehydrogenase release ratio (51.9%) and greatly increased cell apoptosis. The drastic Maillard reaction in duck induced by long roasting time could be advantageous for color, aroma and antioxidant activities in roast ducks, but might be not beneficial to health. © 2015 Society of Chemical Industry.

Two novel pyrrolooxazole pigments formed by the Maillard reaction between glucose and threonine or serine.

PubMed

Noda, Kyoko; Murata, Masatsune

2017-02-01

Pyrrolothiazolate formed by the Maillard reaction between l-cysteine and d-glucose has a pyrrolothiazole skeleton as a chromophore. We searched for a Maillard pigment having a pyrrolooxazole skeleton formed from l-threonine or l-serine instead of l-cysteine in the presence of d-glucose. As a result, two novel yellow pigments, named pyrrolooxazolates A and B, were isolated from model solutions of the Maillard reaction containing l-threonine and d-glucose, and l-serine and d-glucose, respectively, and identified as (2R,3S,7aS)-2,3,7,7a-tetrahydro-6-hydroxy-2,5,7a-trimethyl-7-oxo-pyrrolo[2,1-b]oxazole-3-calboxylic acid and (3S,7aS)-2,3,7,7a-tetrahydro-6-hydroxy-5,7a-dimethyl-7-oxo-pyrrolo[2,1-b]oxazole-3-calboxylic acid by instrumental analyses. These compounds were pyrrolooxazole derivatives carrying a carboxy group, and showed the absorption maxima at 300-360 nm under acidic and neutral conditions and at 320-390 nm under alkaline conditions.

Ovalbumin Modified with Pyrraline, a Maillard Reaction Product, shows Enhanced T-cell Immunogenicity*

PubMed Central

Heilmann, Monika; Wellner, Anne; Gadermaier, Gabriele; Ilchmann, Anne; Briza, Peter; Krause, Maren; Nagai, Ryoji; Burgdorf, Sven; Scheurer, Stephan; Vieths, Stefan; Henle, Thomas; Toda, Masako

2014-01-01

The Maillard reaction (also referred to as “glycation”) takes place between reducing sugars and compounds with free amino groups during thermal processing of foods. In the final stage of the complex reaction cascade, the so-called advanced glycation end products (AGEs) are formed, including proteins with various glycation structures. It has been suggested that some AGEs could have immunostimulatory effects. Here, we aimed to identify specific glycation structure(s) that could influence the T-cell immunogenicity and potential allergenicity of food allergens, using ovalbumin (OVA, an egg white allergen) as a model allergen. OVA was specifically modified with representative glycation structures: Nϵ-carboxymethyl lysine (CM-OVA), Nϵ-carboxyethyl lysine (CE-OVA), pyrraline (Pyr-OVA), or methylglyoxal-derived arginine derivatives (MGO-OVA). As well as AGE-OVA, a crude glycation product in thermal incubation of OVA with glucose, only Pyr-OVA, and not other modified OVAs, was efficiently taken up by bone marrow-derived murine dendritic cells (BMDCs). The uptake of Pyr-OVA was reduced in scavenger receptor class A (SR-A)-deficient BMDCs, but not in cells treated with inhibitors of scavenger receptor class B, galectin-3, or blocking antibodies against CD36, suggesting that pyrraline binds to SR-A. Compared with other modified OVAs, Pyr-OVA induced higher activation of OVA-specific CD4+ T-cells in co-culture with BMDCs. Furthermore, compared with native OVA, AGE-OVA and Pyr-OVA induced higher IgE production in mice. Pyrraline could induce better allergen uptake by DCs via association with SR-A and subsequently enhance CD4+ T-cell activation and IgE production. Our findings help us to understand how Maillard reaction enhances the potential allergenicity of food allergens. PMID:24505139

Evaluation of the extent of initial Maillard reaction during cooking some vegetables by direct measurement of the Amadori compounds.

PubMed

Yu, Jiahao; Zhang, Shuqin; Zhang, Lianfu

2018-01-01

During vegetable cooking, one of the most notable and common chemical reactions is the Maillard reaction, which occurs as a result of thermal treatment and dehydration. Amadori compound determination provides a very sensitive indicator for early detection of quality changes caused by the Maillard reaction, as well as to retrospectively assess the heat treatment or storage conditions to which the product has been subjected. In this paper, a hydrophilic interaction liquid chromatographic-electrospray ionization-tandem mass spectrometric method was developed for the analysis of eight Amadori compounds, and the initial steps of the Maillard reaction during cooking (steaming, frying and baking) bell pepper, red pepper, yellow onion, purple onion, tomato and carrot were also assessed by quantitative determination of these Amadori compounds. These culinary treatments reduced moisture and increased the total content of Amadori compounds, which was not dependent on the type of vegetable or cooking method. Moreover, the effect of steaming on Amadori compound content and water loss was less than that by baking and frying vegetables. Further studies showed that the combination of high temperature and short time may lead to lower formation of Amadori compounds when baking vegetables. Culinary methods differently affected the extent of initial Maillard reaction when vegetables were made into home-cooked products. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Bimolecular interaction of argpyrimidine (a Maillard reaction product) in in vitro non-enzymatic protein glycation model and its potential role as an antiglycating agent.

PubMed

Bhattacherjee, Abhishek; Dhara, Kaliprasanna; Chakraborti, Abhay Sankar

2017-09-01

Non- enzymatic glycation, also known as Maillard reaction, is one of the most important and investigated reactions in biochemistry. Maillard reaction products (MRPs) like protein-derived advanced glycation end products (AGEs) are often referred to cause pathophysiological complications in human systems. On contrary, several MRPs are exogenously used as antioxidant, antimicrobial and flavouring agents. In the preset study, we have shown that argpyrimidine, a well-established AGE, interacts with bovine serum albumin (BSA) and glucose individually in standard BSA-glucose model system and successfully inhibits glycation of the protein. Bimolecular interaction of argpyrimidine with glucose or BSA has been studied independently. Chromatographic purification, different spectroscopic studies and molecular modeling have been used to evaluate the nature and pattern of interactions. Binding of argpyrimidine with BSA prevents incorporation of glucose inside the native protein. Argpyrimidine can also directly entrap glucose. Both these interactions may be associated with the antiglycation potential of argpyrimidine, indicating a beneficial function of an AGE. Copyright © 2017 Elsevier B.V. All rights reserved.

Characteristic antioxidant activity and comprehensive flavor compound profile of scallop (Chlamys farreri) mantle hydrolysates-ribose Maillard reaction products.

PubMed

Han, Jia-Run; Yan, Jia-Nan; Sun, Shi-Guang; Tang, Yue; Shang, Wen-Hui; Li, Ao-Ting; Guo, Xiao-Kun; Du, Yi-Nan; Wu, Hai-Tao; Zhu, Bei-Wei; Xiong, Youling L

2018-09-30

The objective of the present study was to improve the utilization of scallop (Chlamys farreri) byproducts by using Maillard reaction. Scallop mantle hydrolysates (SMHs) were prepared using neutrase then reacted with ribose. Thirty-four peptides were identified from SMHs by UPLC-Q-TOF-MS, and the abundance of Asp and Lys suggested the strong Maillard reactivity. The formation of Schiff's base as well as modification of amide I, II and III bands in Maillard reaction products (MRPs) was confirmed by ultraviolet-visible, fluorescence, and Fourier transform infrared spectroscopy. Thirty volatile compounds were produced by the reaction of SMHs with ribose. Moreover, MRPs with enhanced radical scavenging and anti-linoleic acid peroxidation activities over SMHs promoted the survival and reduced the DNA damage of HepG2 cells treated with hydrogen peroxide. These results suggest that SMHs-ribose MRPs can be potentially used as food antioxidant for suppressing of lipid oxidation or protecting of cell from oxidative damage. Copyright © 2018 Elsevier Ltd. All rights reserved.

Impact of phloretin and phloridzin on the formation of Maillard reaction products in aqueous models composed of glucose and L-lysine or its derivatives.

PubMed

Ma, Jinyu; Peng, Xiaofang; Ng, Kwan-Ming; Che, Chi-Ming; Wang, Mingfu

2012-02-01

In the present study, the effects of phloretin and phloridzin on the formation of Maillard reaction products in a lysine-glucose model with different reactant ratios were systematically investigated. In terms of the formation of Maillard-type volatiles, phloretin and phloridzin treatmen could significantly reduce their generation, where the effects depend on the ratio of lysine to glucose used in the model systems. Phloretin and phloridzin could also affect the colour development of Maillard reactions; especially phloretin, which could significantly promote the formation of brown products in the system with the lowest ratio of lysine to glucose. Based on the carbon module labelling (CAMOLA) technique and HPLC-DAD-ESI/MS analysis, it was found that phloretin and phloridzin could actively participate in the Maillard reaction and directly react with different reactive carbonyl species. The effect of phloretin and phloridzin treatment in both N(α)-acetyllysine-glucose (AC-glu), and N-acetyl-gly-lys methyl ester acetate salt-glucose (AG-glu) model systems, which are close to the Maillard reactions occurring in real food, where the free amino groups of lysine residues were considered as the reactive site, were further investigated. Similar impacts on the formation of Maillard-type volatiles and brown products as in the lysine-glucose models were observed which can also be explained by the capability of phloretin and phloridzin to quench sugar fragments formed in these model reactions.

Microencapsulation of stearidonic acid soybean oil in Maillard reaction-modified complex coacervates.

PubMed

Ifeduba, Ebenezer A; Akoh, Casimir C

2016-05-15

The antioxidant capacity of Maillard reaction (MR)-modified gelatin (GE)-gum arabic (GA) coacervates was optimized to produce microcapsules with superior oxidative stability compared to the unmodified control. MR was used to crosslink GE and GA, with or without maltodextrin (MD), to produce anti-oxidative Maillard reaction products (MRP) which was used to encapsulate stearidonic acid soybean oil (SDASO) by complex coacervation. Biopolymer blends (GE-GA [1:1, w/w] or GE-GA-MD [2:2:1, w/w/w]) were crosslinked by dry-heating at 80°C for 4, 8, or 16h. Relationships between the extent of browning, Trolox equivalent antioxidant capacity (TEAC), and the total oxidation (TOTOX) of encapsulated SDASO were fitted to quadratic models. The [GE-GA-MD] blends exhibited higher browning rates and TEAC values than corresponding [GE-GA] blends. Depending on the type of biopolymer blend and dry-heating time, TOTOX values of SDASO in MRP-derived microcapsules were 29-87% lower than that of the non-crosslinked control after 30 days of storage. Copyright © 2015 Elsevier Ltd. All rights reserved.

Impact of the Maillard reaction on the antioxidant capacity of bovine lactoferrin.

PubMed

Joubran, Yousef; Mackie, Alan; Lesmes, Uri

2013-12-15

Studies raise the notion that the Maillard reaction (MR) may be harnessed to modify the antioxidant capacity of alimentary proteins. However, little is known about the impact of MR on bioactive proteins. Glucose and fructose were used as model moieties reacting with lactoferrin (LF). UV absorbance and SDS-PAGE analyses were used to monitor MR progression during 36 h of mild thermal processing (60 °C, 79% RH). FTIR and CD did not reveal changes in LF structure; However, dynamic light scattering showed MR increased mean particle sizes and sample turbidity at 3Maillard conjugates as a function of reaction time (12 and 36 h), protein:monosaccharide mole ratio (1:1 or 1:3) and moiety type, compared to unprocessed LF. Overall, a link between conjugates' antioxidant capacity and processing parameters is described to enable future attempts to enhance LF functionality in foods containing carbohydrates. Copyright © 2013 Elsevier Ltd. All rights reserved.

Effects of extrusion, infrared and microwave processing on Maillard reaction products and phenolic compounds in soybean.

PubMed

Zilić, Slađana; Mogol, Burçe Ataç; Akıllıoğlu, Gül; Serpen, Arda; Delić, Nenad; Gökmen, Vural

2014-01-15

The Maillard reaction indicators furosine, hydroxymethylfurfural (HMF), acrylamide and color were determined to evaluate heat effects induced during extrusion, infrared and microwave heating of soybean. In addition, the present paper aimed to study changes in the phenolic compounds, as well as in the overall antioxidant properties of different soybean products in relation to heating at 45-140 °C during the processes. Soybean proteins were highly sensible to Maillard reaction and furosine was rapidly formed under slight heating conditions during extrusion and infrared heating. Microwave heating at lower temperatures for a longer time yielded lower acrylamide levels in the final soybean products, as a result of its partial degradation. However, during infrared heating, acrylamide formation greatly increased with decreasing moisture content. After a short time of extrusion and infrared heating at 140 °C and microwave heating at 135 °C for 5 min, concentrations of HMF increased to 11.34, 26.21 and 34.97 µg g(-1), respectively. The heating conditions caused formation of acrylamide, HMF and furosine in high concentration. The results indicate that the complex structure of soybeans provides protection of phenolic compounds from thermal degradation, and that Maillard reaction products improved the antioxidant properties of heat-treated soybean. © 2013 Society of Chemical Industry.

Studies on absorption and elimination of dietary maillard reaction products.

PubMed

Förster, Anke; Kühne, Yvonne; Henle, Thomas

2005-06-01

A nine-day dietary study involving 18 healthy volunteers was performed in order to investigate the influence of nutrition on the urinary excretion of the Maillard reaction products (MRPs) fructoselysine, pyrraline, and pentosidine. From day two through day eight, most types of Maillard product-containing food had to be avoided. On day five, participants were divided into four groups, three of them receiving a test meal (pretzel sticks, brewed coffee, or custard) containing defined amounts of MRPs. The fourth group served as a control. Urine samples taken over a 24-h period were analyzed for MRPs using chromatographic means. As a result of the MRP-free diet, urinary excretion of free pyrraline and fructoselysine, which was calculated from furosine analysis, were lowered about 90%. Excretion of pentosidine decreased about 40%. Consumption of pretzel sticks and coffee on day five resulted in increased amounts of pyrraline and pentosidine in urine samples on days five to seven. Related to the supplied amounts of pyrraline, about 50% were recovered in the urine samples after ingestion of the pretzel sticks. For pentosidine, 60% of the ingested free derivative from coffee brew and 2% of the peptide-bound amino acid ingested with the bakery product were recovered in the urine samples, indicating a better bioavailability for free pentosidine compared to the protein-bound form. For peptide-bound Amadori products, no influence on the excretion was observed after ingestion of the test foods, indicating degradation in the intestine or plasma to yet-unknown metabolites. In conclusion, differences concerning the excretion rate of individual MRPs point to individual resorption and metabolic pathways. These results are of importance for the discussion of a possible (patho)physiological role of dietary advanced glycation end products (AGEs).

Antioxidant activity and sensory characteristics of Maillard reaction products derived from different peptide fractions of soybean meal hydrolysate.

PubMed

Yu, Min; He, Shudong; Tang, Mingming; Zhang, Zuoyong; Zhu, Yongsheng; Sun, Hanju

2018-03-15

Four peptide fractions PF1 (>5;kDa), PF2 (3-5;kDa), PF3 (1-3;kDa), PF4 (<1;kDa) were isolated from soybean hydrolysate using the ultrafiltration method. Then, d-xylose and l-cysteine were reacted with specific peptide solution at 120;°C for 2;h, and the molecular weight distribution (MWD), pH, colour, browning intensity, DPPH radical-scavenging activity, free amino acids and sensory characteristics of corresponding Maillard reaction products (MRPF1, MRPF2, MRPF3 and MRPF4) were evaluated, respectively. Peptides with low molecular weight showed higher contribution to the changes of pH, colour and browning intensity during Maillard reaction. The DPPH radical-scavenging activity of PF4 was significantly improved after Maillard reaction. Aroma volatiles and PLSR analysis suggested MRPF3 had the best sensory characteristics with higher contents of umami amino acids and lower of bitter amino acids, therefore it could be deduced that the umami and meaty characteristics were correlated with the peptides of 1-3;kDa. Copyright © 2017 Elsevier Ltd. All rights reserved.

Inhibition of enzymatic browning in actual food systems by the Maillard reaction products.

PubMed

Mogol, Burçe Ataç; Yildirim, Asli; Gökmen, Vural

2010-12-01

The Maillard reaction occurring between amino acids and sugars produces neo-formed compounds having certain levels of antioxidant activity depending on the reaction conditions and the type of reactants. The objective of this study was to investigate enzymatic browning inhibition capacity of Maillard reaction products (MRPs) formed from different amino acids including arginine (Arg), histidine (His), lysine (Lys) and proline (Pro). The inhibitory effects of the MRPs on polyphenol oxidase (PPO) were determined. The total antioxidant capacity (TAC) of MRPs derived from different amino acids were in the order Arg > His > Lys > Pro. The TAC and PPO inhibition of MRPs were evaluated as a function of temperature (80-120 °C), time (1-6 h) and pH (2-12). Arg-Glc and His-Glc MRPs exhibited strong TAC and PPO inhibition. Increasing temperature (up to 100 °C) and time also increased TAC and PPO inhibition. Kinetics analysis indicated a mixed type inhibition of PPO by MRPs. The results indicate that the MRPs derived from Arg and His under certain reaction conditions significantly prevent enzymatic browning in actual food systems. The intermediate compounds capable of preventing enzymatic browning are reductones and dehydroreductones, as confirmed by liquid chromatographic-mass spectrometric analyses. Copyright © 2010 Society of Chemical Industry.

Fluorescent Carbon Dots Derived from Maillard Reaction Products: Their Properties, Biodistribution, Cytotoxicity, and Antioxidant Activity.

PubMed

Li, Dongmei; Na, Xiaokang; Wang, Haitao; Xie, Yisha; Cong, Shuang; Song, Yukun; Xu, Xianbing; Zhu, Bei-Wei; Tan, Mingqian

2018-02-14

Food-borne nanoparticles have received great attention because of their unique physicochemical properties and potential health risk. In this study, carbon dots (CDs) formed during one of the most important chemical reactions in the food processing field, the Maillard reaction from the model system including glucose and lysine, were investigated. The CDs purified from Maillard reaction products emitted a strong blue fluorescence under ultraviolet light with a fluorescent quantum yield of 16.30%. In addition, they were roughly spherical, with sizes of around 4.3 nm, and mainly composed of carbon, oxygen, hydrogen, and nitrogen. Their surface groups such as hydroxyl, amino, and carboxyl groups were found to possibly enable CDs to scavenge DPPH and hydroxyl radicals. Furthermore, the cytotoxicity assessment of CDs showed that they could readily enter HepG2 cells while causing negligible cell death at low concentration. However, high CDs concentrations were highly cytotoxic and led to cell death via interference of the glycolytic pathway.

Analysis of the Maillard reaction in human hair using Fourier transform infrared spectroscopic imaging and a focal-plane array detector.

PubMed

Jung, In-Keun; Park, Sang-Chul; Bin, Sung-Ah; Roh, Young Sup; Lee, John Hwan; Kim, Boo-Min

2016-03-01

The Maillard reaction has been well researched and used in the food industry and the fields of environmental science and organic chemistry. Here, we induced the Maillard reaction inside human hair and analyzed its effects by using Fourier transform infrared spectroscopy with a focal-plane array (FTIR-FPA) detector. We used arginine (A), glycine (G), and D-xylose (X) to generate the Maillard reaction by dissolving them in purified water and heating it to 150 °C. This label-free process generated a complex compound (named AGX after its ingredients) with a monomer structure, which was determined by using nuclear magnetic resonance (NMR) and FTIR-FPA. This compound was stable in hair and substantially increased its tensile strength. To our knowledge, we are the first to report the formation of this monomer in human hair, and our study provides insights into a new method that could be used to improve the condition of damaged or aging hair.

Impacts of glutathione Maillard reaction products on sensory characteristics and consumer acceptability of beef soup.

PubMed

Hong, J H; Jung, D W; Kim, Y S; Lee, S M; Kim, K O

2010-10-01

The sensory characteristics and consumer acceptability of beef soup with added glutathione Maillard reaction products (GMRPs) were investigated to examine the effects of the GMRPs on beef-soup flavor compared to soups made with glutathione (GSH) and monosodium glutamate (MSG), a control (CON), or a control soup made with 150% beef content (CON150). The sensory characteristics of the beef soups were examined by descriptive analysis. The overall acceptabilities of the beef soups were rated by consumers. Principal component analysis was performed on descriptive data as explanatory variables with overall acceptability as a supplementary variable to observe the relationships between the descriptive data and consumer acceptability, as well as the relationships between the beef-soup samples and their sensory attributes. The samples containing GMRPs had "beef flavor" that was stronger than the CON and MSG samples, and comparable to that of the GSH sample and CON150. The GMRP samples had stronger "green onion flavor,"garlic flavor," and "boiled egg white flavor" than the other samples. The beef soup containing MSG was preferred to CON, CON150, and GSH. The samples with GMRPs were least favored because of their pronounced metallic and astringent notes. The results of this study imply the feasibility of GMRPs as a flavor enhancer since the soups containing these compounds showed more complex flavor profiles than GSH. However, future studies are required to optimize the MR conditions that produce GMRPs without undesirable characteristics. Practical Application: This study examined the practicability of the Maillard reaction products between glutathione (GSH) and glucose (GP) or fructose (FP) as a flavor enhancer by investigating the sensory characteristics and consumer acceptability evoked by them in a beef-soup system. This study helps flavor and food industry to develop a new flavor enhancer by providing practical information, such as beef flavor-enhancing effect of FP and

Maillard-Reaction-Functionalized Egg Ovalbumin Stabilizes Oil Nanoemulsions.

PubMed

Liu, Gang; Yuan, Dan; Wang, Qi; Li, Wanrong; Cai, Jie; Li, Shuyi; Lamikanra, Olusola; Qin, Xinguang

2018-04-25

Egg white proteins are an excellent source of nutrition, with high biological and technological values. However, their limited functional properties prevent their widespread industrial applications. In this study, the ovalbumin functionality was improved via glycation by Maillard reaction with d-lactose. The free amino groups and sodium dodecyl sulfate-polyacrylamide gel electrophoresis profile were determined, confirming that glycation occurred between ovalbumin and lactose. The emulsification of the conjugate was 2.69-fold higher than that of ovalbumin at pH 7.0 after glycation. The thermal stability also improved remarkably. The glycated protein products were used to form an oil-water nanoemulsion for polymethoxyflavone-rich aged orange peel oil. The resulting nanoemulsion showed good pH, thermal, and storage stabilities.

Detection of Maillard reaction products by a coupled HPLC-Fraction collector technique and FTIR characterization of Cu(II)-complexation with the isolated species

NASA Astrophysics Data System (ADS)

Ioannou, Aristos; Daskalakis, Vangelis; Varotsis, Constantinos

2017-08-01

The isolation of reaction products of asparagine with reducing sugars at alkaline pH and high temperature has been probed by a combination of high performance liquid chromatography (HPLC) coupled with a Fraction Collector. The UV-vis and FTIR spectra of the isolated Maillard reaction products showed structure-sensitive changes as depicted by deamination events and formation of asparagine-saccharide conjugates. The initial reaction species of the Asn-Gluc reaction were also characterized by Density Functional Theory (DFT) methods. Evidence for Cu (II) metal ion complexation with the Maillard reaction products is supported by UV-vis and FTIR spectroscopy.

Taste-Active Maillard Reaction Products in Roasted Garlic (Allium sativum).

PubMed

Wakamatsu, Junichiro; Stark, Timo D; Hofmann, Thomas

2016-07-27

In order to gain first insight into candidate Maillard reaction products formed upon thermal processing of garlic, mixtures of glucose and S-allyl-l-cysteine, the major sulfur-containing amino acid in garlic, were low-moisture heated, and nine major reaction products were isolated. LC-TOF-MS, 1D/2D NMR, and CD spectroscopy led to their identification as acortatarin A (1), pollenopyrroside A (2), epi-acortatarin A (3), xylapyrroside A (4), 5-hydroxymethyl-1-[(5-hydroxymethyl-2-furanyl)methyl]-1H-pyrrole-2-carbalde-hyde (5), 3-(allylthio)-2-(2-formyl-5-hydroxymethyl-1H-pyrrol-1-yl)propanoic acid (6), (4S)-4-(allylthiomethyl)-3,4-dihydro-3-oxo-1H-pyrrolo[2,1-c][1,4]oxazine-6-carbaldehyde (7), (2R)-3-(allylthio)-2-[(4R)-4-(allylthiomethyl)-6-formyl-3-oxo-3,4-dihydropyrrolo-[1,2-a]pyrazin-2(1H)-yl]propanoic acid (8), and (2R)-3-(allylthio)-2-((4S)-4-(allylthiomethyl)-6-formyl-3-oxo-3,4-dihydropyrrolo-[1,2-a]pyrazin-2(1H)-yl)propanoic acid (9). Among the Maillard reaction products identified, compounds 5-9 have not previously been published. The thermal generation of the literature known spiroalkaloids 1-4 is reported for the first time. Sensory analysis revealed a bitter taste with thresholds between 0.5 and 785 μmol/kg for 1-5 and 7-9. Compound 6 did not show any intrinsic taste (water) but exhibited a strong mouthfullness (kokumi) enhancing activity above 186 μmol/kg. LC-MS/MS analysis showed 1-9 to be generated upon pan-frying of garlic with the highest concentration of 793.7 μmol/kg found for 6, thus exceeding its kokumi threshold by a factor of 4 and giving evidence for its potential taste modulation activity in processed garlic preparations.

Changes in the physicochemical characteristics, including flavour components and Maillard reaction products, of non-centrifugal cane brown sugar during storage.

PubMed

Asikin, Yonathan; Kamiya, Asahiro; Mizu, Masami; Takara, Kensaku; Tamaki, Hajime; Wada, Koji

2014-04-15

Changes in the quality attributes of non-centrifugal cane brown sugar represented by physicochemical characteristics as well as flavour components and Maillard reaction products (MRPs) were monitored every 3 months over 1 year of storage. Stored cane brown sugar became darker, and its moisture content and water activity (a(w)) increased during storage. Fructose and glucose levels decreased as non-enzymatic browning via the Maillard reaction occurred in the stored sample, and a similar trend was also discovered in aconitic and acetic acids. Stored cane brown sugar lost its acidic and sulfuric odours (58.70-39.35% and 1.85-0.08%, respectively); subsequently, the nutty and roasted aroma increased from 26.52% to 38.59% due to the volatile MRPs. The browning rate of stored cane brown sugar was positively associated with the development of volatile MRPs (Pearson's coefficient = 0.860), whereas the amount of 3-deoxyglucosone, an intermediate product of the Maillard reaction, had a lower association with the brown colour due to its relatively slow degradation rate. Copyright © 2013 Elsevier Ltd. All rights reserved.

Unique Pattern of Protein-Bound Maillard Reaction Products in Manuka (Leptospermum scoparium) Honey.

PubMed

Hellwig, Michael; Rückriemen, Jana; Sandner, Daniel; Henle, Thomas

2017-05-03

As a unique feature, honey from the New Zealand manuka tree (Leptospermum scoparium) contains substantial amounts of dihydroxyacetone (DHA) and methylglyoxal (MGO). Although MGO is a reactive intermediate in the Maillard reaction, very little is known about reactions of MGO with honey proteins. We hypothesized that the abundance of MGO should result in a particular pattern of protein-bound Maillard reaction products (MRPs) in manuka honey. A protein-rich high-molecular-weight fraction was isolated from 12 manuka and 8 non-manuka honeys and hydrolyzed enzymatically. By HPLC-MS/MS, 8 MRPs, namely, N-ε-fructosyllysine, N-ε-maltulosyllysine, carboxymethyllysine, carboxyethyllysine (CEL), pyrraline, formyline, maltosine, and methylglyoxal-derived hydroimidazolone 1 (MG-H1), were quantitated. Compared to non-manuka honeys, the manuka honeys were characterized by high concentrations of CEL and MG-H1, whereas the formation of N-ε-fructosyllysine was suppressed, indicating concurrence reactions of glucose and MGO at the ε-amino group of protein-bound lysine. Up to 31% of the lysine and 8% of the arginine residues, respectively, in the manuka honey protein can be modified to CEL and MG-H1, respectively. CEL and MG-H1 concentrations correlated strongly with the MGO concentration of the honeys. Manuka honey possesses a special pattern of protein-bound MRPs, which might be used to prove the reliability of labeled MGO levels in honeys and possibly enable the detection of fraudulent MGO or DHA addition to honey.

A Laboratory Experiment, Based on the Maillard Reaction, Conducted as a Project in Introductory Statistics

ERIC Educational Resources Information Center

Kravchuk, Olena; Elliott, Antony; Bhandari, Bhesh

2005-01-01

A simple laboratory experiment, based on the Maillard reaction, served as a project in Introductory Statistics for undergraduates in Food Science and Technology. By using the principles of randomization and replication and reflecting on the sources of variation in the experimental data, students reinforced the statistical concepts and techniques…

Sensory characteristics and consumer acceptability of beef stock containing glutathione Maillard reaction products prepared at various conditions.

PubMed

Kwon, G Y; Hong, J H; Kim, Y S; Lee, S M; Kim, K O

2011-01-01

The sensory characteristics and consumer acceptability of beef soup samples containing 9 types of glutathione Maillard reaction products (GMRPs) were investigated to examine the effects of the GMRPs produced under different reaction conditions on the flavor of the beef soup. The sensory characteristics of the beef stocks were examined using descriptive analysis. In consumer testing, 50 consumers evaluated the overall acceptability and flavor intensities of beef odor, salty taste, beef flavor, and seasoning flavor in the beef soup samples. It was found that the reaction conditions, including sugar type and pH, affected the sensory characteristics of the beef stock containing the GMRPs. The samples containing the GMRPs reacted at pH 7 were characterized with strong beef flavor, chestnut flavor, and cooked rice flavor. However, the GMRP reacted with xylose at pH 7 (XM7) was significantly stronger in beef-related sensory characteristics than the GMRPs reacted with glucose or fructose at pH 7 (GM7 and FM7). The samples containing the GMRPs reacted at pH 3 had strong acid-related attributes whereas the GMRPs reacted at pH 11 exhibited strong sulfur-related attributes and a bitter taste. Overall, the beef soup containing XM7, which was perceived as having a strong beef odor and flavor, was rated the highest consumer acceptability score. This suggests that XM7 has feasibility as a flavor enhancer. To elucidate its effectiveness further, it is required to apply XM7 in various food systems at varying levels and to compare its flavor enhancing effects with other flavor enhancers such as monosodium L-glutamate in future studies. Practical Application: This study characterized sensory attributes of glutathione Maillard reaction products (GMRPs) reacted under various conditions and evaluated their potential as a flavor enhancer by examining consumer acceptability of beef stock containing the GMRPs. This study showed that the GMRP reacted with xylose at pH 7 had strong 71 beef

Anti-inflammatory effect of sugar-amino acid Maillard reaction products on intestinal inflammation model in vitro and in vivo.

PubMed

Oh, Jun-Gu; Chun, Su-Hyun; Kim, Da Hyun; Kim, Jin Hye; Shin, Hye Soo; Cho, Yong Soo; Kim, Yong Ki; Choi, Hee-Don; Lee, Kwang-Won

2017-09-08

The Maillard reaction is a nonenzymatic reaction between an amino acid and a reducing sugar that usually occurs upon heating. This reaction occurs routinely in cooking, generates numerous products, which are collectively referred to as Maillard reaction products (MRPs) contributing to aroma and color features. Advanced glycation end-products (AGEs) transformed from MRPs are participated in many types of inflammation reaction. In this study, various sugar-amino acid MRPs were prepared from three different amino acids (lysine, arginine, and glycine) and sugars (glucose, fructose, and galactose) for 1 h with heating at 121 °C. Treatment of lipopolysaccharide-stimulated RAW264.7 macrophages with the MRPs decreased nitric oxide (NO) expression compared to control without MRPs treatment. MRPs derived from lysine and galactose (Lys-Gal MRPs) significantly inhibited NO expression. The retentate fraction of Lys-Gal MRPs with cut-off of molecular weight of 3-10 kDa (LGCM) suppressed NO expression more effectively than did Lys-Gal MRPs. The anti-inflammatory effect of LGCM was evaluated using a co-culture system consisting of Caco-2 (apical side) and RAW264.7 or THP-1 (basolateral side) cells to investigate the gut inflammation reaction by stimulated macrophage cells. In this system, LGCM prevented a decreased transepithelial electrical resistance, and decreased both tumor necrosis factor-α production in macrophages and interleukin (IL)-8 and IL-1β mRNA expression in Caco-2 cells. In co-culture and in vivo dextran sulfate sodium (DSS)-induced colitis model study, we also observed the anti-inflammatory activity of LGCM. Copyright © 2017 Elsevier Ltd. All rights reserved.

On the time behaviour of the concentration of pyrazinium radical cations in the early stage of the Maillard reaction

NASA Astrophysics Data System (ADS)

Stoesser, Reinhard; Klein, Jeannette; Peschke, Simone; Zehl, Andrea; Cämmerer, Bettina; Kroh, Lothar W.

2007-08-01

During the early stage of the Maillard reaction pyrazinium radical cations were detected by ESR within the reaction system D-glucose/glycine. The spectra were characterized by completely resolved hyperfine structure. The partial pressure of oxygen and the radical concentrations were measured directly in the reaction mixture by ESR using solutions of the spin probe TEMPOL and of DPPH, respectively. There are quantitative and qualitative relations of the actual concentration of the radical ions to the partial pressure of oxygen, the temperature-time regime and the mechanical mixing of the reaction system. These macroscopic parameters significantly affect both the induction period and the velocity of the time-dependent formation of free radicals. From in situ variations of p(O 2) and p(Ar) including the connected mixing effects caused by the passing the gases through the reaction mixture, steric and chemical effects of the stabilization of the radical ions were established. The determination of suitable and relevant conditions for stabilization and subsequent radical reactions contributes to the elucidation of the macroscopically known antioxidant activity of Maillard products.

The importance of the Maillard-metal complexes and their silicates in astrobiology

NASA Astrophysics Data System (ADS)

Liesch, Patrick J.; Kolb, Vera M.

2007-09-01

The Maillard reaction occurs when sugars and amino acids are mixed together in the solid state or in the aqueous solution. Since both amino acids and sugar-like compounds are found on meteorites, we hypothesized that they would also undergo the Maillard reaction. Our recent work supports this idea. We have shown previously that the water-insoluble Maillard products have substantial similarities with the insoluble organic materials from the meteorites. The Maillard organic materials are also part of the desert varnish on Earth, which is a dark, shiny, hard rock coating that contains iron and manganese and is glazed in silicate. Rocks that are similar in appearance to the desert varnish have been observed on the Martian surface. They may also contain the organic materials. We have undertaken study of the interactions between the Maillard products, iron and other metals, and silicates, to elucidate the role of the Maillard products in the chemistry of desert varnish and meteorites. Specifically, we have synthesized a series of the Maillard-metal complexes, and have tested their reactivity towards silicates. We have studied the properties of these Maillard-metal-silicate products by the IR spectroscopy. The astrobiological potential of the Maillard-metal complexes is assessed.

Roles of different initial Maillard intermediates and pathways in meat flavor formation for cysteine-xylose-glycine model reaction systems.

PubMed

Hou, Li; Xie, Jianchun; Zhao, Jian; Zhao, Mengyao; Fan, Mengdie; Xiao, Qunfei; Liang, Jingjing; Chen, Feng

2017-10-01

To explore initial Maillard reaction pathways and mechanisms for maximal formation of meaty flavors in heated cysteine-xylose-glycine systems, model reactions with synthesized initial Maillard intermediates, Gly-Amadori, TTCA (2-threityl-thiazolidine-4-carboxylic acids) and Cys-Amadori, were investigated. Relative relativities were characterized by spectrophotometrically monitoring the development of colorless degradation intermediates and browning reaction products. Aroma compounds formed were determined by solid-phase microextraction combined with GC-MS and GC-olfactometry. Gly-Amadori showed the fastest reaction followed by Cys-Amadori then TTCA. Free glycine accelerated reaction of TTCA, whereas cysteine inhibited that of Gly-Amadori due to association forming relatively stable thiazolidines. Cys-Amadori/Gly had the highest reactivity in development of both meaty flavors and brown products. TTCA/Gly favored yielding meaty flavors, whereas Gly-Amadori/Cys favored generation of brown products. Conclusively, initial formation of TTCA and pathway involving TTCA with glycine were more applicable to efficiently produce processed-meat flavorings in a cysteine-xylose-glycine system. Copyright © 2017 Elsevier Ltd. All rights reserved.

Contribution of sulfur-containing compounds to the colour-inhibiting effect and improved antioxidant activity of Maillard reaction products of soybean protein hydrolysates.

PubMed

Huang, Meigui; Liu, Ping; Song, Shiqing; Zhang, Xiaoming; Hayat, Khizar; Xia, Shuqin; Jia, Chengsheng; Gu, Fenglin

2011-03-15

Light-coloured and savoury-tasting flavour enhancers are attractive to both consumers and food producers. The aim of this study was to investigate the colour-inhibiting effect of L-cysteine and thiamine during the Maillard reaction of soybean peptide and D-xylose. The correlation between volatile compounds and antioxidant activity of the corresponding products was also studied. Colour formation was markedly suppressed by cysteine. Compared with peptide/xylose (PX), the taste profile of Maillard reaction products (MRPs) derived from peptide/xylose/cysteine (PXC) and peptide/xylose/cysteine/thiamine (PXCT) was stronger, including umami, mouthfulness, continuity, meaty and overall acceptance. PXC and PXCT also exihibited distinctly higher antioxidant activity. Principal component analysis was applied to investigate the correlation between antioxidant activity and volatile compounds. Of 88 volatile compounds identified, 55 were significantly correlated with antioxidant activity by two principal components (accounting for 85.05% of the total variance). Effective colour control of the Maillard reaction by L-cysteine may allow the production of healthier (higher antioxidant activity) and tastier foods to satisfy consumers' and food producers' demands. Light-coloured products might be used as functional flavour enhancers in various food systems. Copyright © 2010 Society of Chemical Industry.

A study of different indicators of Maillard reaction with whey proteins and different carbohydrates under adverse storage conditions.

PubMed

Leiva, Graciela E; Naranjo, Gabriela B; Malec, Laura S

2017-01-15

This study examined different indicators of each stage of Maillard reaction under adverse storage conditions in a system with whey proteins and lactose or glucose. The analysis of lysine loss by the o-phthaldialdehyde method can be considered a good indicator of the early stage, showing considerable differences in reactivity when systems with mono and disaccharides were analyzed. Capillary electrophoresis proved to be a sensitive method for evaluating the extent of glycosylation of the native proteins, providing valuable information when the loss of lysine was not significant. The estimation of the Amadori compound from the determination of total 5-hydroxymethyl-2-furfuraldehyde would have correlate well with reactive lysine content if the advanced stages of the reaction had not been reached. For assessing the occurrence of the intermediate and final stages, the measurement of free 5-hydroxymethyl-2-furfuraldehyde and color, proved not to be suitable for storage conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Maillard reaction products in bread: A novel semi-quantitative method for evaluating melanoidins in bread.

PubMed

Helou, Cynthia; Jacolot, Philippe; Niquet-Léridon, Céline; Gadonna-Widehem, Pascale; Tessier, Frédéric J

2016-01-01

The aim of this study was to test the methods currently in use and to develop a new protocol for the evaluation of melanoidins in bread. Markers of the early and advanced stages of the Maillard reaction were also followed in the crumb and the crust of bread throughout baking, and in a crust model system. The crumb of the bread contained N(ε)-fructoselysine and N(ε)-carboxymethyllysine but at levels 7 and 5 times lower than the crust, respectively. 5-Hydroxymethylfurfural was detected only in the crust and its model system. The available methods for the semi-quantification of melanoidins were found to be unsuitable for their analysis in bread. Our new method based on size exclusion chromatography and fluorescence measures soluble fluorescent melanoidins in bread. These melanoidin macromolecules (1.7-5.6 kDa) were detected intact in both crust and model system. They appear to contribute to the dietary fibre in bread. Copyright © 2015 Elsevier Ltd. All rights reserved.

The Maillard reaction of a shrimp by-product protein hydrolysate: chemical changes and inhibiting effects of reactive oxygen species in human HepG2 cells.

PubMed

Zha, Fengchao; Wei, Binbin; Chen, Shengjun; Dong, Shiyuan; Zeng, Mingyong; Liu, Zunying

2015-06-01

Recently, much attention has been given to improving the antioxidant activity of protein hydrolysates via the Maillard reaction, but little is known about the cellular antioxidant activity of Maillard reaction products (MRPs) from protein hydrolysates. We first investigated chemical characterization and the cellular antioxidant activity of MRPs in a shrimp (Litopenaeus vannamei) by-product protein hydrolysate (SBH)-glucose system at 110 °C for up to 10 h of heating. Solutions of SBH and glucose were also heated alone as controls. The Maillard reaction greatly resulted in the increase of hydroxymethylfurfural (HMF) and browning intensity, high molecular weight fraction, and reduction of the total amino acid in SBH with the heating time, which correlated well with the free radical scavenging activity of MRPs. MRPs had stronger inhibiting effects on oxidative stress of human HepG2 cells than the original SBH, and its cellular antioxidant activity strongly correlated with free radical scavenging activity, but less affected by the browning intensity and HMF level. The caramelization of glucose partially affected the HMF level and free radical scavenging activity of MRPs, but it was not related to the cellular antioxidant activity. The cellular antioxidant activity of MRPs for 5 h of heating time appeared to reach a maximum level, which was mainly due to carbonyl ammonia condensation reaction. In conclusion, the Maillard reaction is a potential method to increase the cellular antioxidant activity of a shrimp by-product protein hydrolysate, but the higher HMF levels and the lower amino acid content in MRPs should also be considered.

Maillard reaction products as "natural antibrowning" agents in fruit and vegetable technology.

PubMed

Billaud, Catherine; Maraschin, Christelle; Chow, Yin-Naï; Chériot, Sophie; Peyrat-Maillard, Marie-Nöelle; Nicolas, Jacques

2005-07-01

The effects of Maillard reaction products (MRPs), synthesized from a sugar (pentose, hexose, or disaccharide) and either a cysteine-related compound, an amino acid, or a sulfur compound, were investigated on polyphenoloxidase (PPO) activity from apple, mushroom, and eggplant. The optimal conditions for the production of inhibitory MRPs were performed using two-factor and five-level central experimental designs. It resulted that thiol-derived MRPs were highly prone to give rise to inhibitory compounds of PPO activity. Technological assays were also performed to test the efficiency of selected MRPs in the prevention of enzymatic browning in raw and minimally processed fruits and vegetables.

Odors generated from the Maillard reaction affect autonomic nervous activity and decrease blood pressure through the olfactory system.

PubMed

Zhou, Lanxi; Ohata, Motoko; Owashi, Chisato; Nagai, Katsuya; Yokoyama, Issei; Arihara, Keizo

2018-02-01

Systolic blood pressure (SBP) of rats decreases significantly following exposure to the odor generated from the Maillard reaction of protein digests with xylose. This study identified active odorants that affect blood pressure and demonstrated the mechanism of action. Among the four potent odorants that contribute most to the odor of the Maillard reaction sample, 2,5-dimethyl-4-hydroxy-3(2H)-furanone (DMHF) and 5-methyl-2-pyrazinemethanol (MPM) decreased SBP significantly. The earliest decrease in blood pressure was observed 5 min after exposure to DMHF. Application of zinc sulfate to the nasal cavity eliminated the effect. Furthermore, gastric vagal (parasympathetic) nerve activity was elevated and renal sympathetic nerve activity was lowered after exposure to DMHF. It is indicated that DMHF affects blood pressure through the olfactory system, and the mechanism for the effect of DMHF on blood pressure involves the autonomic nervous system. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Structural characterization of bovine beta-lactoglobulin-galactose/tagatose Maillard complexes by electrophoretic, chromatographic, and spectroscopic methods.

PubMed

Corzo-Martínez, Marta; Moreno, F Javier; Olano, Agustín; Villamiel, Mar

2008-06-11

To investigate the influence of the type of carbonyl group of the sugar on the structural changes of proteins during glycation, an exhaustive structural characterization of glycated beta-lactoglobulin with galactose (aldose) and tagatose (ketose) has been carried out. Conjugates were prepared via Maillard reaction at 40 and 50 degrees C, pH 7, and a w = 0.44. The progress of the Maillard reaction was followed by indirect formation of Amadori and Heyns compounds, advanced glycation end products, and brown polymers. The structural characterization of glycoconjugates was conducted by using a number of analytical techniques such as RP-HPLC, isoelectric focusing, MALDI-ToF, SDS-PAGE, size exclusion chromatography, and spectrofluorimetry (tryptophan fluorescence). In addition, the surface hydrophobicity of the beta-lactoglobulin glycoconjugates was also assessed. The results showed a higher reactivity of galactose than tagatose to form the glycoconjugates, probably due to the higher electrophilicity of the aldehyde group. At 40 degrees C, more aggregation was produced when beta-lactoglobulin was conjugated with tagatose as compared to galactose. However, at 50 degrees C hardly any difference was observed in the aggregation produced by galactose and tagatose. These results afford more insight into the importance of the functional group of the carbohydrate moiety during the formation of protein-carbohydrate conjugates via Maillard reaction.

Chemical and antioxidant properties of casein peptide and its glucose Maillard reaction products in fish oil-in-water emulsions.

PubMed

Dong, Shiyuan; Wei, Binbin; Chen, Bingcan; McClements, D Julian; Decker, Eric A

2011-12-28

Maillard reaction products (MRPs) were prepared by reacting casein peptides with different concentrations of glucose at 80 °C for up to 12 h. The chemical properties of MRPs and their effects on lipid oxidation in fish oil-in-water emulsions were investigated. Increasing browning development and absorbance in 294 nm in the MRPs caused an increase in DPPH radical scavenging, but a decrease in iron chelation, which could be related to the loss of free amino groups in the peptides. The MRPs produced with longer reaction time or higher glucose concentrations were less effective in inhibiting lipid oxidation in emulsions at pH 7.0 compared to casein peptides alone. However, the antioxidant activity of MRPs in emulsions at pH 3.0 was not decreased by prolonged heating. The bitterness of MRPs was less than that of the original casein peptides, and bitterness decreased with increasing heating time and glucose concentrations. Therefore, the Maillard reaction was a potential method to reduce the bitterness of casein peptides while not strongly decreasing their antioxidant activity.

Maillard reaction products from highly heated food prevent mast cell number increase and inflammation in a mouse model of colitis.

PubMed

Al Amir, Issam; Dubayle, David; Héron, Anne; Delayre-Orthez, Carine; Anton, Pauline M

2017-12-01

Links between food and inflammatory bowel diseases (IBDs) are often suggested, but the role of food processing has not been extensively studied. Heat treatment is known to cause the loss of nutrients and the appearance of neoformed compounds such as Maillard reaction products. Their involvement in gut inflammation is equivocal, as some may have proinflammatory effects, whereas other seem to be protective. As IBDs are associated with the recruitment of immune cells, including mast cells, we raised the hypothesis that dietary Maillard reaction products generated through heat treatment of food may limit the colitic response and its associated recruitment of mast cells. An experimental model of colitis was used in mice submitted to mildly and highly heated rodent food. Adult male mice were divided in 3 groups and received nonheated, mildly heated, or highly heated chow during 21 days. In the last week of the study, each group was split into 2 subgroups, submitted or not (controls) to dextran sulfate sodium (DSS) colitis. Weight variations, macroscopic lesions, colonic myeloperoxidase activity, and mucosal mast cell number were evaluated at the end of the experiment. Only highly heated chow significantly prevented DSS-induced weight loss, myeloperoxidase activity, and mast cell number increase in the colonic mucosa of DSS-colitic mice. We suggest that Maillard reaction products from highly heated food may limit the occurrence of inflammatory phases in IBD patients. Copyright © 2017 Elsevier Inc. All rights reserved.

Correlating enzymatic browning inhibition and antioxidant ability of Maillard reaction products derived from different amino acids.

PubMed

Xu, Haining; Zhang, Xiaoming; Karangwa, Eric; Xia, Shuqin

2017-09-01

Up to now, only limited research on enzymatic browning inhibition capacity (BIC) of Maillard reaction products (MRPs) has been reported and there are still no overall and systematic researches on MRPs derived from different amino acids. In the present study, BIC and antioxidant capacity, including 2,2-diphenyl-1-picrylhydrazyl radical scavenging activity and Fe 2+ reducing power activity, of the MRPs derived from 12 different amino acids and three reducing sugars were investigated. The MRPs of cysteine (Cys), cystine, arginine (Arg) and histidine (His) showed higher BIC compared to other amino acids. Lysine (Lys)-MRPs showed the highest absorbance value at 420 nm (A 420 ) but very limited BIC, whereas Cys-MRPs, showed the highest BIC and the lowest A 420 . The A 420 can roughly reflect the trend of BIC of MRPs from different amino acids, except Cys and Lys. MRPs from tyrosine (Tyr) showed the most potent antioxidant capacity but very limited BIC, whereas Cys-MRPs showed both higher antioxidant capacity and BIC compared to other amino acids. Partial least squares regression analysis showed positive and significant correlation between BIC and Fe 2+ reducing power of MRPs from 12 amino acids with glucose or fructose, except Lys, Cys and Tyr. The suitable pH for generating efficient browning inhibition compounds varies depending on different amino acids: acidic pH was favorable for Cys, whereas neutral and alkaline pH were suitable for His and Arg, respectively. Increasing both heating temperature and time over a certain range could improve the BIC of MRPs of Cys, His and Arg, whereas any further increase deteriorates their browning inhibition efficiencies. The types of amino acid, initial pH, temperature and time of the Maillard reaction were found to greatly influence the BIC and antioxidant capacity of the resulting MRPs. There is no clear relationship between BIC and the antioxidant capacity of MRPs when reactant type and processing parameters of the Maillard

Effects of cationic species on visual color formation in model Maillard reactions of pentose sugars and amino acids.

PubMed

Rizzi, George P

2008-08-27

Effects of cationic species on Maillard browning were examined after heating (ca. 100 degrees C) aqueous pH 7.2 buffered solutions of amino acids and pentose sugars. Metallic ions of Group I metals (Li, Na, K, Rb and Cs) produced a small increase in browning (A420), but somewhat greater effects were observed with ions of Group II metals Ca and Mg. Browning was suppressed by triethylammonium ion, but unaffected by a salt of the stronger base, guanidine. The quaternary amine salt choline chloride produced enhanced browning and served as a model for phospholipid involvement in Maillard reactions. With alpha,omega-diamino acids increases in browning were observed which related to lowered pK2 values resulting from positively charged omega-substituents in these molecules.

Maillard Proteomics: Opening New Pages

PubMed Central

Soboleva, Alena; Schmidt, Rico; Vikhnina, Maria; Grishina, Tatiana; Frolov, Andrej

2017-01-01

Protein glycation is a ubiquitous non-enzymatic post-translational modification, formed by reaction of protein amino and guanidino groups with carbonyl compounds, presumably reducing sugars and α-dicarbonyls. Resulting advanced glycation end products (AGEs) represent a highly heterogeneous group of compounds, deleterious in mammals due to their pro-inflammatory effect, and impact in pathogenesis of diabetes mellitus, Alzheimer’s disease and ageing. The body of information on the mechanisms and pathways of AGE formation, acquired during the last decades, clearly indicates a certain site-specificity of glycation. It makes characterization of individual glycation sites a critical pre-requisite for understanding in vivo mechanisms of AGE formation and developing adequate nutritional and therapeutic approaches to reduce it in humans. In this context, proteomics is the methodology of choice to address site-specific molecular changes related to protein glycation. Therefore, here we summarize the methods of Maillard proteomics, specifically focusing on the techniques providing comprehensive structural and quantitative characterization of glycated proteome. Further, we address the novel break-through areas, recently established in the field of Maillard research, i.e., in vitro models based on synthetic peptides, site-based diagnostics of metabolism-related diseases (e.g., diabetes mellitus), proteomics of anti-glycative defense, and dynamics of plant glycated proteome during ageing and response to environmental stress. PMID:29231845

Characterisation of manganese peroxidase and laccase producing bacteria capable for degradation of sucrose glutamic acid-Maillard reaction products at different nutritional and environmental conditions.

PubMed

Kumar, Vineet; Chandra, Ram

2018-02-02

Maillard reactions products (MRPs) are a major colorant of distillery effluent. It is major source of environmental pollution due to its complex structure and recalcitrant nature. This study has revealed that sucrose glutamic acid-Maillard reaction products (SGA-MRPs) showed many absorption peaks between 200 and 450 nm. The absorption maximum peak was noted at 250 nm in spectrophotometric detection. This indicated the formation of variable molecular weight Maillard products during the SGA-MRPs formation at high temperature. The identified aerobic bacterial consortium consisting Klebsiella pneumoniae (KU726953), Salmonella enterica (KU726954), Enterobacter aerogenes (KU726955), Enterobacter cloaceae (KU726957) showed optimum production of MnP and laccase at 120 and 144 h of growth, respectively. The potential bacterial consortium showed decolourisation of Maillard product up to 70% in presence of glucose (1%), peptone (0.1%) at optimum pH (8.1), temperature (37 °C) and shaking speed (180 rpm) within 192 h of incubation. The reduction of colour of Maillard product correlated with shifting of absorption peaks in UV-Vis spectrophotometry analysis. Further, the changing of functional group in FT-IR data showed appearance of new peaks and GC-MS analysis of degraded sample revealed the depolymerisation of complex MRPs. The toxicity evaluation using seed of Phaseolus mungo L. showed reduction of toxicity of MRPs after bacterial treatment. Hence, this study concluded that developed bacterial consortium have capability for decolourisation of MRPs due to high content of MnP and laccase.

Evaluation of maillard reaction variables and their effect on heterocyclic amine formation in chemical model systems.

PubMed

Dennis, Cara; Karim, Faris; Smith, J Scott

2015-02-01

Heterocyclic amines (HCAs), highly mutagenic and potentially carcinogenic by-products, form during Maillard browning reactions, specifically in muscle-rich foods. Chemical model systems allow examination of in vitro formation of HCAs while eliminating complex matrices of meat. Limited research has evaluated the effects of Maillard reaction parameters on HCA formation. Therefore, 4 essential Maillard variables (precursors molar concentrations, water amount, sugar type, and sugar amounts) were evaluated to optimize a model system for the study of 4 HCAs: 2-amino-3-methylimidazo-[4,5-f]quinoline, 2-amino-3-methylimidazo[4,5-f]quinoxaline, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, and 2-amino-3,4,8-trimethyl-imidazo[4,5-f]quinoxaline. Model systems were dissolved in diethylene glycol, heated at 175 °C for 40 min, and separated using reversed-phase liquid chromatography. To define the model system, precursor amounts (threonine and creatinine) were adjusted in molar increments (0.2/0.2, 0.4/0.4, 0.6/0.6, and 0.8/0.8 mmol) and water amounts by percentage (0%, 5%, 10%, and 15%). Sugars (lactose, glucose, galactose, and fructose) were evaluated in several molar amounts proportional to threonine and creatinine (quarter, half, equi, and double). The precursor levels and amounts of sugar were significantly different (P < 0.05) in regards to total HCA formation, with 0.6/0.6/1.2 mmol producing higher levels. Water concentration and sugar type also had a significant effect (P < 0.05), with 5% water and lactose producing higher total HCA amounts. A model system containing threonine (0.6 mmol), creatinine (0.6 mmol), and glucose (1.2 mmol), with 15% water was determined to be the optimal model system with glucose and 15% water being a better representation of meat systems. © 2015 Institute of Food Technologists®

Effect of ultrasound pretreatment and Maillard reaction on structure and antioxidant properties of ultrafiltrated smooth-hound viscera proteins-sucrose conjugates.

PubMed

Abdelhedi, Ola; Mora, Leticia; Jemil, Ines; Jridi, Mourad; Toldrá, Fidel; Nasri, Moncef; Nasri, Rim

2017-09-01

The effect of ultrasound (US) pre-treatment on the evolution of Maillard reaction (MR), induced between low molecular weight (LMW) peptides and sucrose, was studied. LMW peptides (<1kDa) were obtained by the ultrafiltration of smooth hound viscera protein hydrolysates, produced by Neutrase, Esperase and Purafect. MR was induced by heating the LMW peptides in the presence of sucrose for 2h at 90°C, without or with US pre-treatment. During the reaction, a marked decrease in pH values, coupled to the increase in colour of the Maillard reaction products (MRPs), were recorded. In addition, after sonication, the glycation degree was significantly enhanced in Esperase-derived peptides/sucrose conjugates (p<0.05). Moreover, results showed that thermal heating, particularly after US treatment, reduced the bitter taste and enhanced the antioxidant capacities of the resulting conjugates. Hence, it could be concluded that US leads to efficient mixing of sugar-protein solution and efficient heat/mass transfer, contributing to increase the MR rate. Copyright © 2017 Elsevier Ltd. All rights reserved.

Optimised formation of blue Maillard reaction products of xylose and glycine model systems and associated antioxidant activity.

PubMed

Yin, Zi; Sun, Qian; Zhang, Xi; Jing, Hao

2014-05-01

A blue colour can be formed in the xylose (Xyl) and glycine (Gly) Maillard reaction (MR) model system. However, there are fewer studies on the reaction conditions for the blue Maillard reaction products (MRPs). The objective of this study is to investigate characteristic colour formation and antioxidant activities in four different MR model systems and to determine the optimum reaction conditions for the blue colour formation in a Xyl-Gly MR model system, using the random centroid optimisation program. The blue colour with an absorbance peak at 630 nm appeared before browning in the Xyl-Gly MR model system, while no blue colour formation but only browning was observed in the xylose-alanine, xylose-aspartic acid and glucose-glycine MR model systems. The Xyl-Gly MR model system also showed higher antioxidant activity than the other three model systems. The optimum conditions for blue colour formation were as follows: xylose and glycine ratio 1:0.16 (M:M), 0.20 mol L⁻¹ NaHCO₃, 406.1 mL L⁻¹ ethanol, initial pH 8.63, 33.7°C for 22.06 h, which gave a much brighter blue colour and a higher peak at 630 nm. A characteristic blue colour could be formed in the Xyl-Gly MR model system and the optimum conditions for the blue colour formation were proposed and confirmed. © 2013 Society of Chemical Industry.

Optimization of Maillard reaction with ribose for enhancing anti-allergy effect of fish protein hydrolysates using response surface methodology.

PubMed

Yang, Sung-Yong; Kim, Se-Wook; Kim, Yoonsook; Lee, Sang-Hoon; Jeon, Hyeonjin; Lee, Kwang-Won

2015-06-01

Halibut is served on sushi and as sliced raw fish fillets. We investigated the optimal conditions of the Maillard reaction (MR) with ribose using response surface methodology to reduce the allergenicity of its protein. A 3-factored and 5-leveled central composite design was used, where the independent variables were substrate (ribose) concentration (X1, %), reaction time (X2, min), and pH (X3), while the dependent variables were browning index (Y1, absorbance at 420nm), DPPH scavenging (Y2, EC50 mg/mL), FRAP (Y3, mM FeSO4/mg extract) and β-hexosaminidase release (Y4, %). The optimal conditions were obtained as follows: X1, 28.36%; X2, 38.09min; X3, 8.26. Maillard reaction products of fish protein hydrolysate (MFPH) reduced the amount of nitric oxide synthesis compared to the untreated FPH, and had a significant anti-allergy effect on β-hexosaminidase and histamine release, compared with that of the FPH control. We concluded that MFPH, which had better antioxidant and anti-allergy activities than untreated FPH, can be used as an improved dietary source. Copyright © 2014 Elsevier Ltd. All rights reserved.

A potential fluorescent probe: Maillard reaction product from glutathione and ascorbic acid for rapid and label-free dual detection of Hg(2+) and biothiols.

PubMed

Dong, Jiang Xue; Song, Xiao Fang; Shi, Yan; Gao, Zhong Feng; Li, Bang Lin; Li, Nian Bing; Luo, Hong Qun

2016-07-15

Maillard reactions and their fluorescent products have drawn much attention in the fields of food and life science, however, the application of fluorescent products separated from the reaction as an indicator for detection of certain substances in sensor field has not been mentioned. In this article, we report on an easy-to-synthesize and water-soluble fluorescent probe separated from the typical Maillard reaction products of glutathione and ascorbic acid, with excellent stability and high quantum yield (18.2%). The further application of the probe has been explored for dual detection of Hg(2+) and biothiols including cysteine, homocysteine, and glutathione, which is based on Hg(2+)-induced fluorescence quenching of the Maillard reaction fluorescent products (MRFPs) and the fluorescence recovery as the introduction of biothiols. This sensing system exhibits a good selectivity and sensitivity, and the linear ranges for Hg(2+), cysteine, homocysteine, and glutathione are 0.05-12, 0.5-10, 0.3-20, and 0.3-20μM, respectively. The detection limits for Hg(2+), cysteine, homocysteine, and glutathione are 22, 47, 96, and 30nM at a signal-to-noise ratio of 3, respectively. Furthermore, the practical applications of this sensor for Hg(2+) and biothiols determination in water samples and human plasma sample have been demonstrated with satisfactory results. Copyright © 2016 Elsevier B.V. All rights reserved.

Colour and surface fluorescence development and their relationship with Maillard reaction markers as influenced by structural changes during cornflakes production.

PubMed

Farroni, Abel; Buera, María Del Pilar

2012-12-01

The aim of this work was to study colour and surface fluorescence development in relation to the chemical markers for the Maillard reaction at the cooking, flaking and toasting stages of cornflake production process. Colour was measured by a calibrated computer vision system. Surface fluorescence was measured on compressed samples. Aqueous extracted Maillard reaction markers (hydroxymethylfurfural, carboxymethyl-lysine, absorbance at 420nm and total fluorescence) were measured on protease hydrolyzed samples. Sample microstructure was observed by scanning electron microscopy. During cooking the colour coordinates L(∗) and b(∗) decreased and a(∗) increased. After flaking, the samples appeared lighter, while the pigment concentration, fluorescence and hydroxymethylfurfural did not change. Toasting generated bubbles in the matrix and L(∗) apparently increased, although brown pigment concentration increased. Pigment concentration did not correlate with surface colour due to the destruction or generation of interfaces. Surface and microstructure effects can be avoided by milling and compressing the samples. Copyright © 2012 Elsevier Ltd. All rights reserved.

Effect of Maillard browning reaction on protein utilization and plasma amino acid response by rainbow trout (Salmo gairdneri).

PubMed

Plakas, S M; Lee, T C; Wolke, R E; Meade, T L

1985-12-01

The effect of the Maillard browning reaction in the diet of rainbow trout (Salmo gairdneri) on growth and amino acid availability was investigated. Chemical and enzymatic hydrolysis methods were applied for the detection of the losses of amino acids in a model protein browning system. Arginine and lysine exhibited the greatest losses in the mixture of fish protein isolate and glucose stored for 40 d at 37 degrees C. The apparent digestibility and absorption of individual amino acids, particularly lysine, was lower in trout fed browned protein than in those fed the control protein. Plasma lysine levels were significantly depressed, while the plasma levels of glucose and most other amino acids were elevated in relation to the loss in nutritive value of dietary protein after browning. The early Maillard reaction derivative of lysine, epsilon-deoxy-fructosyl-lysine, was recovered from browned protein (by using the in vitro enzymatic hydrolysis procedure) and from the plasma of trout fed browned protein. Analysis of plasma free amino acids provided an indication of lysine bioavailability and identified lysine as the first-limiting amino acid in the diets containing browned protein.

Functional properties of nisin-carbohydrate conjugates formed by radiation induced Maillard reaction

NASA Astrophysics Data System (ADS)

Muppalla, Shobita R.; Sonavale, Rahul; Chawla, Surinder P.; Sharma, Arun

2012-12-01

Nisin-carbohydrate conjugates were prepared by irradiating nisin either with glucose or dextran. Increase in browning and formation of intermediate products was observed with a concomitant decrease in free amino and reducing sugar groups indicating occurrence of the Maillard reaction catalyzed by irradiation. Nisin-carbohydrate conjugates showed a broad spectrum antibacterial activity against Gram negative bacteria (Escherichia coli, Pseudomonas fluorescence) as well as Gram positive bacteria (Staphylococcus aureus, Bacillus cereus). Results of antioxidant assays, including that of DPPH radical-scavenging activity and reducing power, showed that the nisin-dextran conjugates possessed better antioxidant potential than nisin-glucose conjugate. These results suggested that it was possible to enhance the functional properties of nisin by preparing radiation induced conjugates suitable for application in food industry.

In vitro antioxidant and cytoprotective properties of Maillard reaction products from phloridzin-amino acid model systems.

PubMed

Han, Linna; Li, Feng; Yu, Qijian; Li, Dapeng

2018-01-01

The aim of this study was to investigate in vitro antioxidant activities and cytoprotective effect of Maillard reaction products (MRPs) from phloridzin (Pz)-amino acid model systems. Their structures were also characterised by Fourier transform-infrared spectroscopy (FTIR). MRPs were prepared from the Pz-methionine (Met), Pz-lysine (Lys), Pz-isoleucine (Ile), Pz-histidine (His) or Pz-glutamic acid (Glu) model system. The Pz-Lys MRPs, rich in antioxidant potency, were subjected to ultrafiltration to yield four MRPs fractions with different molecular weights (Mw). The fraction with Mw 30-50 kDa had significantly (P < 0.05) higher antioxidant activity than other fractions. Moreover, it significantly (P < 0.05) attenuated the 2,2'-azobis(2-methylpropionamidine) dihydrochloride (AAPH)-elicited decrease in cell viability in HepG2 cells in a concentration-dependent manner. FTIR analysis indicated that the fraction with Mw 30-50 kDa had the strong stretching vibration for the OH, NH, CH, CO and CC groups, suggesting the formation of intermediate MRPs during Maillard reaction. The results obtained in this study may provide some basis for the purported health-promoting effects of MRPs and their potential application as antioxidant agents in food industry. Also, it is important for our understanding of the variation of bioactive substances in food during thermal processing. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

The quantification of free Amadori compounds and amino acids allows to model the bound Maillard reaction products formation in soybean products.

PubMed

Troise, Antonio Dario; Wiltafsky, Markus; Fogliano, Vincenzo; Vitaglione, Paola

2018-05-01

The quantification of protein bound Maillard reaction products (MRPs) is still a challenge in food chemistry. Protein hydrolysis is the bottleneck step: it is time consuming and the protein degradation is not always complete. In this study, the quantitation of free amino acids and Amadori products (APs) was compared to the percentage of blocked lysine by using chemometric tools. Eighty thermally treated soybean samples were analyzed by mass spectrometry to measure the concentration of free amino acids, free APs and the protein-bound markers of the Maillard reaction (furosine, Nε-(carboxymethyl)-l-lysine, Nε-(carboxyethyl)-l-lysine, total lysine). Results demonstrated that Discriminant Analysis (DA) and Correlated Component Regression (CCR) correctly estimated the percent of blocked lysine in a validation and prediction set. These findings indicate that the measure of free markers reflects the extent of protein damage in soybean samples and it suggests the possibility to obtain rapid information on the quality of the industrial processes. Copyright © 2017 Elsevier Ltd. All rights reserved.

Tracking the behavior of Maillard browning in lysine/arginine-sugar model systems under high hydrostatic pressure.

PubMed

Ma, Xiao-Juan; Gao, Jin-Yan; Tong, Ping; Li, Xin; Chen, Hong-Bing

2017-12-01

High-pressure processing is gaining popularity in the food industry. However, its effect on the Maillard reaction during high-pressure-assisted pasteurization and sterilization is not well documented. This study aimed to investigate the effects of high hydrostatic pressure on the Maillard reaction during these processes using amino acid (lysine or arginine)-sugar (glucose or fructose) solution models. High pressure retarded the intermediate and final stages of the Maillard reaction in the lysine-sugar model. For the lysine-glucose model, the degradation rate of Amadori compounds was decelerated, while acceleration was observed in the arginine-sugar model. Increased temperature not only accelerated the Maillard reaction over time but also formed fluorescent compounds with different emission wavelengths. Lysine reacted with the sugars more readily than arginine under the same conditions. In addition, it was easier for lysine to react with glucose, whereas arginine reacted more readily with fructose under high pressure. High pressure exerts different effects on lysine-sugar and arginine-sugar models. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

The decrease in the IgG-binding capacity of intensively dry heated whey proteins is associated with intense Maillard reaction, structural changes of the proteins and formation of RAGE-ligands.

PubMed

Liu, Fahui; Teodorowicz, Małgorzata; van Boekel, Martinus A J S; Wichers, Harry J; Hettinga, Kasper A

2016-01-01

Heat treatment is the most common way of milk processing, inducing structural changes as well as chemical modifications in milk proteins. These modifications influence the immune-reactivity and allergenicity of milk proteins. This study shows the influence of dry heating on the solubility, particle size, loss of accessible thiol and amino groups, degree of Maillard reaction, IgG-binding capacity and binding to the receptor for advanced glycation end products (RAGE) of thermally treated and glycated whey proteins. A mixture of whey proteins and lactose was dry heated at 130 °C up to 20 min to mimic the baking process in two different water activities, 0.23 to mimic the heating in the dry state and 0.59 for the semi-dry state. The dry heating was accompanied by a loss of soluble proteins and an increase in the size of dissolved aggregates. Most of the Maillard reaction sites were found to be located in the reported conformational epitope area on whey proteins. Therefore the structural changes, including exposure of the SH group, SH-SS exchange, covalent cross-links and the loss of available lysine, subsequently resulted in a decreased IgG-binding capacity (up to 33%). The binding of glycation products to RAGE increased with the heating time, which was correlated with the stage of the Maillard reaction and the decrease in the IgG-binding capacity. The RAGE-binding capacity was higher in samples with a lower water activity (0.23). These results indicate that the intensive dry heating of whey proteins as it occurs during baking may be of importance to the immunological properties of allergens in cow's milk, both due to chemical modifications of the allergens and formation of AGEs.

A stimuli-responsive fluorescence platform for simultaneous determination of D-isoascorbic acid and Tartaric acid based on Maillard reaction product

NASA Astrophysics Data System (ADS)

Zhao, Yanmei; Yuan, Haiyan; Zhang, Xinling; Yang, Jidong

2018-05-01

An activatable fluorescence monitoring platform based on a novel Maillard reaction product from D-glucose and L-arginine was prepared through a facile one-pot approach and applied for simultaneous detection of D-isoascorbic acid and tartaric acid. In this work, the new Maillard reaction product GLA was first obtained, and its fluorescence intensity can be effectively quenched by KMnO4, resulting from a new complex (GLA-KMnO4) formation between GLA and KMnO4. Upon addition of D-isoascorbic acid or tartaric acid, an enhanced fluorescence was observed under the optimumed experimental conditions, indicating a stimuli-responsive fluorescence turn on platform for D-isoascorbic acid or tartaric acid can be developed. The corresponding experimental results showed that this turn on fluorescence sensing platform has a high sensitivity for D-isoascorbic acid or tartaric acid, because the detection limits were 5.9 μM and 21.5 μM, respectively. Additionally, this proposed sensing platform was applied to simultaneously detection of D-isoascorbic acid and tartaric acid in real tap water samples with satisfactory results.

Prior lactose glycation of caseinate via the Maillard reaction affects in vitro activities of the pepsin-trypsin digest toward intestinal epithelial cells.

PubMed

Wang, X P; Zhao, X H

2017-07-01

The well-known Maillard reaction in milk occurs between lactose and milk proteins during thermal treatment, and its effects on milk nutrition and safety have been well studied. A lactose-glycated caseinate was prepared via this reaction and digested using 2 digestive proteases, pepsin and trypsin. The glycated caseinate digest was assessed for its in vitro activities on rat intestinal epithelial cells in terms of growth proliferation, anti-apoptotic effect, and differentiation induction using caseinate digest as reference, to verify potential effects of the Maillard reaction on these activities of caseinate digest to the cells. Two digests had proliferative and anti-apoptotic effects, and reached the highest effects at 0.02 g/L of digest concentration with treatment time of 24 h. In comparison with caseinate digest, glycated caseinate digest always showed weaker proliferative (5.3-14.2%) and anti-apoptotic (5.9-39.0%) effects, and was more toxic to the cells at 0.5 g/L of digest concentration with treatment time of 48 h. However, glycated caseinate digest at 2 incubation times of 4 to 7 d showed differentiation induction higher than caseinate digest, as it could confer the cells with increased activities in lactase (16.3-26.6%), sucrase (22.4-31.2%), and alkaline phosphatase (17.4-24.8%). Transmission electron microscopy observation results also confirmed higher differentiation induction of glycated caseinate digest. Amino acid loss and lactose glycation partially contributed to these decreased and enhanced activities of glycated caseinate digest, respectively. The Maillard reaction of caseinate and lactose is thus shown in this study to have effects on the activities of caseinate digest to intestinal epithelial cells. Copyright © 2017 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Using an enzymatic galactose assay to detect lactose glycation extents of two proteins caseinate and soybean protein isolate via the Maillard reaction.

PubMed

Wang, Xiao-Peng; Zhao, Xin-Huai

2017-06-01

Glycation of food proteins via the Maillard reaction has been widely studied in the recent years; however, the amount of saccharide connected to proteins is usually not determined. An enzymatic galactose assay was proposed firstly in this study to detect lactose glycation extents of caseinate and soybean protein isolate (SPI) during the Maillard reaction at two temperatures and different times. The separated glycated proteins were hydrolysed to release galactose necessary for the enzymatic assay and glycation calculation. Caseinate and SPI both obtained the highest lactose glycation extents at 100 °C or 121 °C by a reaction time of 180 or 20 min. Short- and long-time reaction resulted in lower glycation extents. During the reaction, three chemical indices (absorbences at 294/490 nm and fluorescence intensities) of reaction mixtures increased continually, but another index reactable NH 2 of glycated proteins showed the opposite trend. In general, changing profiles of the four indices were inconsistent with those profiles of lactose glycation extents of glycated proteins, implying practical limitation of the four indices in studies. This proposed enzymatic assay could directly detect lactose glycation of the two proteins, and thus was more useful than the four chemical indices to monitor glycation of the two proteins. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Evolution of protein bound Maillard reaction end-products and free Amadori compounds in low lactose milk in presence of fructosamine oxidase I.

PubMed

Troise, Antonio Dario; Buonanno, Martina; Fiore, Alberto; Monti, Simona Maria; Fogliano, Vincenzo

2016-12-01

Thermal treatments and storage influence milk quality, particularly in low lactose milk as the higher concentration of reducing sugars can lead to the increased formation of the Maillard reaction products (MRPs). The control of the Amadori products (APs) formation is the key step to mitigate the Maillard reaction (MR) in milk. The use of fructosamine oxidases, (Faox) provided promising results. In this paper, the effects of Faox I were evaluated by monitoring the concentration of free and bound MRPs in low lactose milk during shelf life. Results showed that the enzyme reduced the formation of protein-bound MRPs down to 79% after six days at 37°C. Faox I lowered the glycation of almost all the free amino acids resulting effective on basic and polar amino acids. Data here reported corroborate previous findings on the potentiality of Faox enzymes in controlling the early stage of the MR in foods. Copyright © 2016 Elsevier Ltd. All rights reserved.

A combination of quantitative marinating and Maillard reaction to enhance volatile flavor in Chinese marinated chicken.

PubMed

Wei, Xiuli; Wang, Chunqing; Zhang, Chunhui; Li, Xia; Wang, Jinzhi; Li, Hai; Tang, Chunhong

2017-02-01

A combination of quantitative marinating and Maillard reaction was investigated by adding d-xylose, l-cysteine and thiamine to the marinated brine of quantitative marinating, which was expected to enhance the volatile flavor of Chinese marinated chicken. Response surface methodology was used to optimize parameters, in which response was sensory evaluation scores of marinated chicken. A Box-Behnken center design was applied to the optimized added contents. The optimized contents were d-xylose (1-5‰), l-cysteine (1-5‰) and thiamine (1-3‰). Analysis of variance indicated that a second-order polynomial equation could predict the experimental data well (R 2  = 0.94), and sensory evaluation scores were significantly affected by the added amount of d-xylose, l-cysteine and thiamine. The optimal conditions that maximized the sensory evaluation score of Chinese marinated chicken were found to be 4.96‰ d-xylose, 2.28‰ l-cysteine and 2.66‰ thiamine (w/w). Given these optimal conditions, a number of meat-like flavor compounds such as 2-pentyl-furan, benzothiazole and 4-methyl-5-thiazoleethanol were identified by gas chromatographic-mass spectrometric analysis. Our results suggested that a combination of quantitative marinating and Maillard reaction might be a promising method to enhance the volatile flavor, especially meat-like flavor, of Chinese marinated chicken. © 2016 Society of Chemical Industry. © 2016 Society of Chemical Industry.

Effects of Maillard reaction products in a glucose-glycine alcoholic solution on antioxidative and antimutagenic activities.

PubMed

Ko, Chih-Yuan; Chen, Xiao-Yu; Chang, Wen-Chang; Zeng, Yi-Ming; Lin, Ru-Hai; Zhang, Xiao-Bin; Wu, James Swi-Bea; Shen, Szu-Chuan

2018-04-12

Marinating meat with alcohol, such as wine and beer, is a common culinary practice in cultures worldwide. This study we use a model marination solution comprising 0.2 M glucose-0.2 M glycine buffered to pH 4.3 containing either 0% or 50% ethanol and mimicked the cooking process by heating for 12 h. Antioxidative and antimutagenic characteristics of Maillard reaction products (MRPs) were investigated. Reducing power, antioxidant activity (Fe 2+ chelating ability) and free radical neutralization ability generated from DPPH and ABTS were determined. Ames testing was performed. Results indicate that MRPs from aqueous and alcoholic solution exhibit four antioxidative assays in a dose-dependent manner from 0.16 to 10.00 mg mL -1 . However, MRPs from the alcoholic model was superior. In Ames testing, MRPs from both models are neither toxic nor mutagenic at the test concentrations of 0.63-10.00 mg plate -1 . However, MRPs from the alcoholic model exhibited a higher inhibitory effect on the direct-acting mutagen 4-NQNO compared to the aqueous model. This result is consistent with the observation that MRPs with higher antioxidative capacity exhibit superior antimutagenic activity, suggesting that there are more different products in the alcoholic model. Our results add to the current knowledge about the antioxidative and antimutagenic properties of Maillard reaction products arising when food is cooked in the presence of ethanol. This article is protected by copyright. All rights reserved.

Characterisation of Maillard reaction products derived from LEKFD--a pentapeptide found in β-lactoglobulin sequence, glycated with glucose--by tandem mass spectrometry, molecular orbital calculations and gel filtration chromatography coupled with continuous photodiode array.

PubMed

Yamaguchi, Keiko; Homma, Takeshi; Nomi, Yuri; Otsuka, Yuzuru

2014-02-15

Maillard reaction peptides (MRPs) contribute to taste, aroma, colour, texture and biological activity. However, peptide degradation or the cross-linking of MRPs in the Maillard reaction has not been investigated clearly. A peptide of LEKFD, a part of β-lactoglobulin, was heated at 110 °C for 24h with glucose and the reaction products were analysed by HPLC with ODS, ESI-MS, ESI-MS/MS and HPLC with gel-filtration column and DAD detector. In the HPLC fractions, an imminium ion of LEK*FD, a pyrylium ion or a hydroxymethyl furylium ion of LEK*FD, and KFD and EK were detected by ESI-MS. Therefore, those products may be produced by the Maillard reaction. The molecular orbital of glycated LEKFD at the lysine epsilon-amino residue with Schiff base form was calculated by MOPAC. HPLC with gel-filtration column showed cross-linking and degradation of peptides. Copyright © 2013 Elsevier Ltd. All rights reserved.

Free and Protein-Bound Maillard Reaction Products in Beer: Method Development and a Survey of Different Beer Types.

PubMed

Hellwig, Michael; Witte, Sophia; Henle, Thomas

2016-09-28

The Maillard reaction is important for beer color and flavor, but little is known about the occurrence of individual glycated amino acids in beer. Therefore, seven Maillard reaction products (MRPs), namely, fructosyllysine, maltulosyllysine, pyrraline, formyline, maltosine, MG-H1, and argpyrimidine, were synthesized and quantitated in different types of beer (Pilsner, dark, bock, wheat, and nonalcoholic beers) by HPLC-ESI-MS/MS in the multiple reaction monitoring mode through application of the standard addition method. Free MRPs were analyzed directly. A high molecular weight fraction was isolated by dialysis and hydrolyzed enzymatically prior to analysis. Maltulosyllysine was quantitated for the first time in food. The most important free MRPs in beer are fructosyllysine (6.8-27.0 mg/L) and maltulosyllysine (3.7-21.8 mg/L). Beer contains comparatively high amounts of late-stage free MRPs such as pyrraline (0.2-1.6 mg/L) and MG-H1 (0.3-2.5 mg/L). Minor amounts of formyline (4-230 μg/L), maltosine (6-56 μg/L), and argpyrimidine (0.1-4.1 μg/L) were quantitated. Maltulosyllysine was the most significant protein-bound MRP, but both maltulosyllysine and fructosyllysine represent only 15-60% of the total protein-bound lysine-derived Amadori products. Differences in the patterns of protein-bound and free individual MRPs and the ratios between them were identified, which indicate differences in their chemical, biochemical, and microbiological stabilities during the brewing process.

Density functional computational studies on the glucose and glycine Maillard reaction: Formation of the Amadori rearrangement products

NASA Astrophysics Data System (ADS)

Jalbout, Abraham F.; Roy, Amlan K.; Shipar, Abul Haider; Ahmed, M. Samsuddin

Theoretical energy changes of various intermediates leading to the formation of the Amadori rearrangement products (ARPs) under different mechanistic assumptions have been calculated, by using open chain glucose (O-Glu)/closed chain glucose (A-Glu and B-Glu) and glycine (Gly) as a model for the Maillard reaction. Density functional theory (DFT) computations have been applied on the proposed mechanisms under different pH conditions. Thus, the possibility of the formation of different compounds and electronic energy changes for different steps in the proposed mechanisms has been evaluated. B-Glu has been found to be more efficient than A-Glu, and A-Glu has been found more efficient than O-Glu in the reaction. The reaction under basic condition is the most favorable for the formation of ARPs. Other reaction pathways have been computed and discussed in this work.0

Multiresponse kinetic modelling of Maillard reaction and caramelisation in a heated glucose/wheat flour system.

PubMed

Kocadağlı, Tolgahan; Gökmen, Vural

2016-11-15

The study describes the kinetics of the formation and degradation of α-dicarbonyl compounds in glucose/wheat flour system heated under low moisture conditions. Changes in the concentrations of glucose, fructose, individual free amino acids, lysine and arginine residues, glucosone, 1-deoxyglucosone, 3-deoxyglucosone, 3,4-dideoxyglucosone, 5-hydroxymethyl-2-furfural, glyoxal, methylglyoxal and diacetyl concentrations were determined to form a multiresponse kinetic model for isomerisation and degradation reactions of glucose. Degradation of Amadori product mainly produced 1-deoxyglucosone. Formation of 3-deoxyglucosone proceeded directly from glucose and also Amadori product degradation. Glyoxal formation was predominant from glucosone while methylglyoxal and diacetyl originated from 1-deoxyglucosone. Formation of 5-hydroxymethyl-2-furfural from fructose was found to be a key step. Multi-response kinetic modelling of Maillard reaction and caramelisation simultaneously indicated quantitatively predominant parallel and consecutive pathways and rate limiting steps by estimating the reaction rate constants. Copyright © 2016 Elsevier Ltd. All rights reserved.

Preparation, characterization and toxicology properties of α- and β-chitosan Maillard reaction products nanoparticles.

PubMed

Zhang, Hongcai; Zhang, Yiwen; Bao, Erjaing; Zhao, Yanyun

2016-08-01

In this study, β-chitosan (CS) Maillard reaction (MR) NPs was prepared to improve the water solubility of CS NPs. The α- and β-CS MR was firstly induced by high intensity ultrasound-assisted (UA) water-bath heating at 80°C for 8h. The α- and β-CS Maillard reaction products (MRPs NPs were then prepared by ionic gelation method between the positively charged primary amino groups of CS and the negatively charged groups of sodium tripolyphosphate (TPP). The α- and β-CS MRPs NPs had particle size of 42.49 and 61.74nm, and Zeta-potential of 27.43 and 35.13mV, respectively. The prepared α- and β-CS MRPs NPs was characterized by transmission electron microscope (TEM), Fourier transform infrared spectrometer (FT-IR), X-ray diffraction (XRD) and thermogravimetric analysis (TGA)-differential scanning calorimetry (DSC) to verify whether α- and β-CS MRPs has been incorporated into the CS NPs. The α- and β-CS MRPs NPs exhibited no significant difference (p>0.05) in antioxidant activity compared with α- and β-CS MRPs at the same concentration based on reducing power, DPPH radical scavenging activity, and ORAC values. The cytotoxicity test of α- and β-CS MRPs NPs showed good cell viability (70.86-99.16%) of human pulmonary microvascular endothelial cells (HLMVEC) at the concentration range from 0.12 to 1mg/mL, and fluorescein-5-isothiocyanate (FITC)-α- and β-CS MRPs NPs maintained the morphological characteristics of living cells. These results showed that α- and β-CS MRPs NPs can be used as water-soluble antioxidant substances for applications in food and other fields. Copyright © 2016. Published by Elsevier B.V.

Protective Effects of Maillard Reaction Products of Whey Protein Concentrate against Oxidative Stress through an Nrf2-Dependent Pathway in HepG2 Cells.

PubMed

Pyo, Min Cheol; Yang, Sung-Yong; Chun, Su-Hyun; Oh, Nam Su; Lee, Kwang-Won

2016-09-01

Whey protein concentrate (WPC), which contains α-lactalbumin and β-lactoglobulin, is utilized widely in the food industry. The Maillard reaction is a complex reaction that produces Maillard reaction products (MRPs), which are associated with the formation of antioxidant compounds. In this study, the hepatoprotection activity of MRPs of WPC against oxidative stress through the nuclear factor-E2-related factor 2 (Nrf2)-dependent antioxidant pathway in HepG2 cells was examined. Glucose-whey protein concentrate conjugate (Glc-WPC) was obtained from Maillard reaction between WPC and glucose. The fluorescence intensity of Glc-WPC increased after 7 d compared to native WPC, and resulted in loss of 48% of the free amino groups of WPC. The sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE) patterns of Glc-WPC showed the presence of a high-molecular-weight portion. Treatment of HepG2 cells with Glc-WPC increased cell viability in the presence of oxidative stress, inhibited the generation of intracellular reactive oxygen species by tert-butyl hydroperoxide (t-BHP), and increased the glutathione level. Nrf2 translocation and Nrf2, reduced nicotinamide adenine dinucleotide phosphate (NAD(P)H)-quinone oxidoreductase 1 (NOQ1), heme oxygenase-1 (HO-1), glutamate-L-cysteine ligase (GCL)M and GCLC mRNA levels were increased by Glc-WPC. Also, Glc-WPC increased the phosphorylation of extracellular signal-regulated kinase (ERK) 1/2 and c-Jun N-terminal kinase (JNK). The results of this study demonstrate that Glc-WPC activates the Nrf2-dependent pathway through the phosphorylation of ERK1/2 and JNK in HepG2 cells, and induces production of antioxidant enzymes and phase II enzymes.

A stimuli-responsive fluorescence platform for simultaneous determination of d-isoascorbic acid and Tartaric acid based on Maillard reaction product.

PubMed

Zhao, Yanmei; Yuan, Haiyan; Zhang, Xinling; Yang, Jidong

2018-05-05

An activatable fluorescence monitoring platform based on a novel Maillard reaction product from d-glucose and L-arginine was prepared through a facile one-pot approach and applied for simultaneous detection of d-isoascorbic acid and tartaric acid. In this work, the new Maillard reaction product GLA was first obtained, and its fluorescence intensity can be effectively quenched by KMnO 4 , resulting from a new complex (GLA-KMnO 4 ) formation between GLA and KMnO 4 . Upon addition of d-isoascorbic acid or tartaric acid, an enhanced fluorescence was observed under the optimumed experimental conditions, indicating a stimuli-responsive fluorescence turn on platform for d-isoascorbic acid or tartaric acid can be developed. The corresponding experimental results showed that this turn on fluorescence sensing platform has a high sensitivity for d-isoascorbic acid or tartaric acid, because the detection limits were 5.9μM and 21.5μM, respectively. Additionally, this proposed sensing platform was applied to simultaneously detection of d-isoascorbic acid and tartaric acid in real tap water samples with satisfactory results. Copyright © 2018 Elsevier B.V. All rights reserved.

Chemical characteristics and enhanced hepatoprotective activities of Maillard reaction products derived from milk protein-sugar system.

PubMed

Oh, Nam Su; Young Lee, Ji; Lee, Hyun Ah; Joung, Jae Yeon; Shin, Yong Kook; Kim, Sae Hun; Kim, Younghoon; Lee, Kwang Won

2016-02-01

The objective of this study was to investigate the characteristics, antioxidative properties, and hepatoprotective effects of Maillard reaction products (MRP) from milk protein reacted with sugars. The MRP were obtained from milk protein, whey protein concentrates and sodium caseinate, using 2 types of sugars, lactose and glucose, by heating the mixture at 55°C for 7d in a sodium phosphate buffer (pH 7.4). Changes in the chemical modification of the milk protein were monitored by measuring the protein-bound carbonyls and PAGE protein profiles. The results showed that the amount of protein-bound carbonyls increased after Maillard reaction (MR). In addition, sodium dodecyl sulfate-PAGE analysis indicated a formation of high-molecular weight complexes through MR. The modification sites induced by MR of milk protein were monitored by matrix-assisted laser desorption/ionization time-of-flight mass spectrometry analysis of tryptic-digested gel spots of MRP. As a result, modification and their localization in AA sequence of MRP was identified. Also, the MRP showed higher antioxidant activities than the intact milk protein, and they reduced intracellular reactive oxygen species production and inhibited the depletion of the reduced glutathione concentrations in the HepG2 cells. In particular, glucose-sodium caseinate MRP showed the highest biological activities among all MRP. Therefore, these results suggest that the MRP from milk protein reacting with sugars possess effective antioxidant activity and have a protective ability against oxidative damage. Copyright © 2016 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

[Proteins modified in the nonenzymatically glycosylation reaction (AGE-proteins)--new markers for diabetes?].

PubMed

Zdrojewicz, Z; Januszewski, A; Kwiatkowska, D

1994-01-01

Paper present a recent review on the formation and clinical significance of advanced glycosylation end products, produced in nonenzymatically glycosylation, called Maillard reaction. The special attention was paid to AGEs role in diabetic and aging processes. Instant of occurring of AGEs in circulation or increase of AGE receptor concentration are many years faster than clinical pathology of vessels, nervous or kidneys connect with diabetes or aging. May be in the future it will be possible to decrease the consequence of Maillard reaction by using pharmacology drugs.

Antioxidative, Antibacterial, and Food Functional Properties of the Half-Fin Anchovy Hydrolysates-Glucose Conjugates Formed via Maillard Reaction.

PubMed

Song, Ru; Yang, Peiyu; Wei, Rongbian; Ruan, Guanqiang

2016-06-20

The antioxidative, antibacterial, and food functional properties of the half-fin anchovy hydrolysates (HAHp)-glucose conjugates formed by Maillard reaction (MR) were investigated, respectively. Results of sugar and amino acid contents loss rates, browning index, and molecular weight distribution indicated that the initial pH of HAHp played an important role in the process of MR between HAHp and glucose. HAHp-glucose Maillard reaction products (HAHp-G MRPs) demonstrated enhanced antioxidative activities of reducing power and scavenging DPPH radicals compared to control groups. HAHp-G MRPs produced from the condition of pH 9.6 displayed the strongest reducing power. The excellent scavenging activity on DPPH radicals was found for HAHp(5.6)-G MRPs which was produced at pH 5.6. Additionally, HAHp(5.6)-G MRPs showed variable antibacterial activities against Escherichia coli, Pseudomonas fluorescens, Proteus vulgaris, Pseudomonas aeruginosa, Staphylococcus aureus, Bacillus subtilis, Bacillus megaterium, and Sarcina lutea, with the MIC values ranging from 8.3 to 16.7 μg/mL. Result of scanning electron microscopy (SEM) on E. coli suggested that HAHp(5.6)-G MRPs exhibited antibacterial activity by destroying the cell integrity through membrane permeabilization. Moreover, HAHp(5.6)-G MRPs had excellent foaming ability and stability at alkaline conditions of pH 8.0, and showed emulsion properties at acidic pH 4.0. These results suggested that specific HAHp-G MRPs should be promising functional ingredients used in foods.

Dietary Maillard reaction products and their fermented products reduce cardiovascular risk in an animal model.

PubMed

Oh, N S; Park, M R; Lee, K W; Kim, S H; Kim, Y

2015-08-01

This study examined the effects of Maillard reaction products (MRP) and MRP fermented by lactic acid bacteria on antioxidants and their enhancement of cardiovascular health in ICR mouse and rat models. In previous in vitro studies, the selected lactic acid bacteria were shown to significantly affect the activity of MRP. The expression of genes (e.g., superoxide dismutase, catalase, and glutathione peroxidase) related to antioxidant activity was upregulated by Maillard-reacted sodium caseinate (cMRP), and cMRP fermented by Lactobacillus fermentum H9 (F-cMRP) synergistically increased the expression of catalase and superoxide dismutase when compared with the high-cholesterol-diet group. Bleeding time, the assay for determination of antithrombotic activity, was significantly prolonged by Maillard-reacted whey protein concentration (wMRP) and wMRP fermented by Lactobacillus gasseri H10 (F-wMRP), similar to the bleeding time of the aspirin group (positive control). In addition, the acute pulmonary thromboembolism-induced mice overcame severe body paralysis or death in both the wMRP and the F-wMRP groups. In the serum-level experiment, cMRP and F-cMRP significantly reduced the serum total and low-density lipoprotein cholesterol levels and triglycerides but had only a slight effect on high-density lipoprotein cholesterol. The levels of aspartate transaminase and alanine transaminase also declined in the cMRP and F-cMRP intake groups compared with the high-cholesterol-diet group. In particular, F-cMRP showed the highest reducing effects on triglycerides, aspartate transaminase, and alanine transaminase. Moreover, the expression of cholesterol-related genes in the F-cMRP group demonstrated greater effects than for the cMRP group in the level of cholesterol 7 α-hydroxylase (CYP7A1), 3-hydroxy-3-methylglutaryl-CoA reductase (HMGR), and low-density lipoprotein receptors compared with the high-cholesterol-diet group. The protective role of cMRP and F-cMRP in the high

In situ formation of the amino sugars 1-amino-1-deoxy-fructose and 2-amino-2-deoxy-glucose under Maillard reaction conditions in the absence of ammonia.

PubMed

Nashalian, Ossanna; Yaylayan, Varoujan A

2016-04-15

Replacing amino acids with their binary metal complexes during the Maillard reaction can initiate various processes, including the oxidative degradation of their glucose conjugates, generating 1-amino-1-deoxy-fructose and its derivatives. These reactive amino sugars are not easily accessible under Maillard reaction conditions and are only formed in the presence of ammonia. To explore the generality of this observation and to study in particular the ability of fructose to generate glucosamine, the amino acid-metal complexes were heated in aqueous solutions with three aldohexoses and two ketohexoses at 110°C for 2 h and the dry residues were analysed by ESI/qTOF/MS/MS. All the sugars generated relatively intense ions at [M+H](+) 180 (C6H14NO5); those ions originating from ketohexoses exhibited MS/MS fragmentations identical to glucosamine and those originating form aldohexoses showed ions identical to fructosamine. Furthermore, the amino sugars were found to form fructosazine, react with other sugars and undergo dehydration reactions. Copyright © 2015 Elsevier Ltd. All rights reserved.

Synthesis, optimization and structural characterization of a chitosan-glucose derivative obtained by the Maillard reaction.

PubMed

Gullón, Beatriz; Montenegro, María I; Ruiz-Matute, Ana I; Cardelle-Cobas, Alejandra; Corzo, Nieves; Pintado, Manuela E

2016-02-10

Chitosan (Chit) was submitted to the Maillard reaction (MR) by co-heating a solution with glucose (Glc). Different reaction conditions as temperature (40, 60 and 80 °C), Glc concentration (0.5%, 1%, and 2%, w/v), and reaction time (72, 52 and 24h) were evaluated. Assessment of the reaction extent was monitored by measuring changes in UV absorbance, browning and fluorescence. Under the best conditions, 2% (w/v) of Chit, 2% (w/v) of Glc at 60°C and 32 h of reaction time, a chitosan-glucose (Chit-Glc) derivative was purified and submitted to structural characterization to confirm its formation. Analysis of its molecular weight (MW) and the degree of substitution (DS) was carried out by HPLC-Size Exclusion Chromatography (SEC) and a colloid titration method, respectively. FT-IR and (1)H NMR were also used to analyze the functional groups and evaluate the introduction of Glc into the Chit molecule. According to our objectives, the results obtained in this work allowed to better understand the key parameters influencing the MR with Chit as well as to confirm the successful introduction of Glc into the Chit molecule obtaining a Chit-Glc derivative with a DS of 64.76 ± 4.40% and a MW of 210.37 kDa. Copyright © 2015 Elsevier Ltd. All rights reserved.

Glycation of a food allergen by the Maillard reaction enhances its T-cell immunogenicity: role of macrophage scavenger receptor class A type I and II.

PubMed

Ilchmann, Anne; Burgdorf, Sven; Scheurer, Stephan; Waibler, Zoe; Nagai, Ryoji; Wellner, Anne; Yamamoto, Yasuhiko; Yamamoto, Hiroshi; Henle, Thomas; Kurts, Christian; Kalinke, Ulrich; Vieths, Stefan; Toda, Masako

2010-01-01

The Maillard reaction occurs between reducing sugars and proteins during thermal processing of foods. It produces chemically glycated proteins termed advanced glycation end products (AGEs). The glycation structures of AGEs are suggested to function as pathogenesis-related immune epitopes in food allergy. This study aimed at defining the T-cell immunogenicity of food AGEs by using ovalbumin (OVA) as a model allergen. AGE-OVA was prepared by means of thermal processing of OVA in the presence of glucose. Activation of OVA-specific CD4(+) T cells by AGE-OVA was evaluated in cocultures with bone marrow-derived murine myeloid dendritic cells (mDCs) as antigen-presenting cells. The uptake mechanisms of mDCs for AGE-OVA were investigated by using inhibitors of putative cell-surface receptors for AGEs, as well as mDCs deficient for these receptors. Compared with the controls (native OVA and OVA thermally processed without glucose), AGE-OVA enhanced the activation of OVA-specific CD4(+) T cells on coculture with mDCs, indicating that the glycation of OVA enhanced the T-cell immunogenicity of the allergen. The mDC uptake of AGE-OVA was significantly higher than that of the controls. We identified scavenger receptor class A type I and II (SR-AI/II) as a mediator of the AGE-OVA uptake, whereas the receptor for AGEs and galectin-3 were not responsible. Importantly, the activation of OVA-specific CD4(+) T cells by AGE-OVA was attenuated on coculture with SR-AI/II-deficient mDCs. SR-AI/II targets AGE-OVA to the MHC class II loading pathway in mDCs, leading to an enhanced CD4(+) T-cell activation. The Maillard reaction might thus play an important role in the T-cell immunogenicity of food allergens. Copyright 2010 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

Food-Grade Synthesis of Maillard-Type Taste Enhancers Using Natural Deep Eutectic Solvents (NADES).

PubMed

Kranz, Maximilian; Hofmann, Thomas

2018-01-28

The increasing demand for healthier food products, with reduced levels of table salt, sugar, and mono sodium glutamate, reinforce the need for novel taste enhancers prepared by means of food-grade kitchen-type chemistry. Although several taste modulating compounds have been discovered in processed foods, their Maillard-type ex food production is usually not exploited by industrial process reactions as the yields of target compounds typically do not exceed 1-2%. Natural deep eutectic solvents (NADES) are reported for the first time to significantly increase the yields of the taste enhancers 1-deoxy-ᴅ-fructosyl-N-β-alanyl-ʟ-histidine (49% yield), N-(1-methyl-4-oxoimidazolidin-2-ylidene) aminopropionic acid (54% yield) and N²-(1-carboxyethyl) guanosine 5'-monophosphate (22% yield) at low temperature (80-100 °C) within a maximum reaction time of 2 h. Therefore, NADES open new avenues to a "next-generation culinary chemistry" overcoming the yield limitations of traditional Maillard chemistry approaches and enable a food-grade Maillard-type generation of flavor modulators.

Metabolomic approach for determination of key volatile compounds related to beef flavor in glutathione-Maillard reaction products.

PubMed

Lee, Sang Mi; Kwon, Goo Young; Kim, Kwang-Ok; Kim, Young-Suk

2011-10-10

The non-targeted analysis, combining gas chromatography coupled with time-of-flight mass spectrometry (GC-TOF/MS) and sensory evaluation, was applied to investigate the relationship between volatile compounds and the sensory attributes of glutathione-Maillard reaction products (GSH-MRPs) prepared under different reaction conditions. Volatile compounds in GSH-MRPs correlating to the sensory attributes were determined using partial least-squares (PLS) regression. Volatile compounds such as 2-methylfuran-3-thiol, 3-sulfanylpentan-2-one, furan-2-ylmethanethiol, 2-propylpyrazine, 1-furan-2-ylpropan-2-one, 1H-pyrrole, 2-methylthiophene, and 2-(furan-2-ylmethyldisulfanylmethyl)furan could be identified as possible key contributors to the beef-related attributes of GSH-MRPs. In this study, we demonstrated that the unbiased non-targeted analysis based on metabolomic approach allows the identification of key volatile compounds related to beef flavor in GSH-MRPs. Copyright © 2011 Elsevier B.V. All rights reserved.

Mitigation strategies of acrylamide, furans, heterocyclic amines and browning during the Maillard reaction in foods.

PubMed

Rannou, Cécile; Laroque, Delphine; Renault, Emilie; Prost, Carole; Sérot, Thierry

2016-12-01

The Maillard reaction (MR) occurs widely during food manufacture and storage, through controlled or uncontrolled pathways. Its consequences are ambiguous depending on the nature and processing of the food products. The MR is often used by food manufacturer to develop appealing aromas, colour or texture in food products (cereal based food, coffee, meat…). However, despite some positive aspects, the MR could decrease the nutritional value of food, generate potentially harmful compounds (e.g. acrylamide, furans, heterocyclic amines) or modify aroma or colour although it is not desired (milk, fruit juice). This paper presents a review of the different solutions available to control or moderate the MR in various food products from preventive to removal methods. A brief reminder of the role and influence of the MR on food quality and safety is also provided. Copyright © 2016 Elsevier Ltd. All rights reserved.

Repeated Oral Exposure to N ε-Carboxymethyllysine, a Maillard Reaction Product, Alleviates Gut Microbiota Dysbiosis in Colitic Mice.

PubMed

ALJahdali, Nesreen; Gadonna-Widehem, Pascale; Delayre-Orthez, Carine; Marier, David; Garnier, Benjamin; Carbonero, Franck; Anton, Pauline M

2017-12-01

Diet is suggested to participate in the etiology of inflammatory bowel diseases (IBD). Repeated exposure to Maillard reaction products (MRPs), molecules resulting from reduction reactions between amino acids and sugars during food heating, has been reported to be either potentially detrimental or beneficial to health. The aim of this study is to determine the effect of repeated oral ingestion of N ε -carboxymethyllysine (CML), an advanced MRP, on the onset of two models of experimental IBD and on the gut microbiota composition of mice. Mice received either saline (control) or N ε -carboxymethyllysine daily for 21 days. For the last week of treatment, each group was split into subgroups, receiving dextran sulfate sodium salt (DSS) or trinitrobenzenesulfonic acid (TNBS) to induce colitis. Intensity of inflammation was quantified, and cecal microbiota characterized by bacterial 16S ribosomal RNA (rRNA) amplicon sequencing. Daily oral administration of N ε -carboxymethyllysine did not induce intestinal inflammation and had limited impact on gut microbiota composition (Bacteroidaceae increase, Lachnospiraceae decrease). DSS and TNBS administration resulted in expected moderate experimental colitis with a shift of Bacteroidetes/Firmicutes ratio and a significant Proteobacteria increase but with distinct profiles: different Proteobacteria taxa for DSS, but mainly Enterobacteriaceae for TNBS. While N ε -carboxymethyllysine exposure failed to prevent the inflammatory response, it allowed maintenance of healthy gut microbiota profiles in mice treated with DSS (but not TNBS). Repeated oral exposure to CML limits dysbiosis in experimental colitis. IBD patients may modulate their microbiota profile by regulating the level and type of dietary MRP consumption.

Autoxidation of packed almonds as affected by maillard reaction volatile compounds derived from roasting.

PubMed

Severini, C; Gomes, T; De Pilli, T; Romani, S; Massini, R

2000-10-01

Shelled almonds of two Italian varieties, Romana and Pizzuta, peeled and unpeeled, were roasted and packed under different conditions: air (control), vacuum, and Maillard reaction volatile compounds (MRVc) derived from the roasting process. Samples were stored for approximately 8 months at room temperature, without light, and, at regular intervals, were collected and analyzed to evaluate the progress of lipid oxidation. Peroxide values, triglyceride oligopolymers, and oxidized triglycerides were evaluated during the storage time. Results showed that, although the MRVc atmosphere did not protect the lipid fraction of almonds as well as the vacuum condition; nevertheless, it was more protective than the control atmosphere, showing an antioxidant effect. The effect of the natural coating was a strong protection against lipid oxidation; in fact, only the unpeeled samples showed peroxide values lower than the threshold of acceptability (25 milliequiv of O(2)/kg of oil). Moreover, at the end of the storage period, Pizzuta almonds showed a greater deterioration than those of the Romana variety.

Formation of Reactive Intermediates, Color, and Antioxidant Activity in the Maillard Reaction of Maltose in Comparison to d-Glucose.

PubMed

Kanzler, Clemens; Schestkowa, Helena; Haase, Paul T; Kroh, Lothar W

2017-10-11

In this study, the Maillard reaction of maltose and d-glucose in the presence of l-alanine was investigated in aqueous solution at 130 °C and pH 5. The reactivity of both carbohydrates was compared in regards of their degradation, browning, and antioxidant activity. In order to identify relevant differences in the reaction pathways, the concentrations of selected intermediates such as 1,2-dicarbonyl compounds, furans, furanones, and pyranones were determined. It was found, that the degradation of maltose predominantly yields 1,2-dicarbonyls that still carry a glucosyl moiety and thus subsequent reactions to HMF, furfural, and 2-acetylfuran are favored due to the elimination of d-glucose, which is an excellent leaving group in aqueous solution. Consequently, higher amounts of these heterocycles are formed from maltose. 3-deoxyglucosone and 3-deoxygalactosone represent the only relevant C 6 -1,2-dicarbonyls in maltose incubations and are produced in nearly equimolar amounts during the first 60 min of heating as byproducts of the HMF formation.

Assessment of Maillard reaction evolution, prebiotic carbohydrates, antioxidant activity and α-amylase inhibition in pulse flours.

PubMed

Moussou, Nadia; Corzo-Martínez, Marta; Sanz, María Luz; Zaidi, Farid; Montilla, Antonia; Villamiel, Mar

2017-03-01

In this paper, the quality of bean, chickpea, fava beans, lentil and pea flours from Algeria has been evaluated. Maillard reaction (MR) indicators, modifications in the carbohydrate and protein fractions, antioxidant activity and α-amylase inhibitor of raw, toasted and stored samples were evaluated. Fava beans, beans and peas showed higher content of raffinose family oligosaccharides while chickpeas and lentils showed higher polyol content. Toasting and storage caused slightly change in pulse quality; MR showed slight losses of lysine but increased antioxidant activity. Moreover, inhibition of α-amylase was slightly augmented during processing; this could increase the undigested carbohydrates that reach the colon, modulating the glycemic response. These results point out the suitability of these flours for preparing high-quality foodstuffs intended for a wide spectrum of the population, including hyperglycemic and gluten intolerant individuals.

Characterization and emulsifying properties of β-lactoglobulin-gum Acacia Seyal conjugates prepared via the Maillard reaction.

PubMed

Bi, Binwei; Yang, Hao; Fang, Yapeng; Nishinari, Katsuyoshi; Phillips, Glyn O

2017-01-01

Gum Acacia Seyal (ASY) is less valued than is gum Acacia Senegal, due to its poor emulsifying ability. The present study investigated the Maillard reaction between ASY and β-lactoglobulin (BLG) and its impact on the emulsifying properties of ASY. The reaction products of BLG/ASY mixture (r=1/4), prepared by dry-heating at 60°C and a relative humidity of 79%, as a function of incubation time, were characterized by SDS-PAGE, GPC-MALLS and DSC. The results showed that 12-24h of dry-heating under the given conditions was sufficient for conjugation, meanwhile avoiding the formation of deeply coloured and insoluble melanoidins. More than 64% of the protein was incorporated into ASY, resulting in a two-fold increase in arabinogalactan-protein (AGP) content and 3.5 times increase in weight-average molecular mass of ASY. The conjugation with BLG markedly improved the stability of ASY-stabilized emulsions and their resistance against severe conditions, such as low pH and high saline conditions. Copyright © 2016 Elsevier Ltd. All rights reserved.

Sodium sulfite pH-buffering effect for improved xylose-phenylalanine conversion to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine during an aqueous Maillard reaction.

PubMed

Cui, Heping; Duhoranimana, Emmanuel; Karangwa, Eric; Jia, Chengsheng; Zhang, Xiaoming

2018-04-25

The yield of the Maillard reaction intermediate (MRI), prepared in aqueous medium, is usually unsatisfactory. However, the addition of sodium sulfite could improve the conversion of xylose-phenylalanine (Xyl-Phe) to the MRI (N-(1-deoxy-d-xylulos-1-yl)-phenylalanine) in aqueous medium. Sodium sulfite (Na 2 SO 3 ) showed a significant pH-buffering effect during the Maillard reaction, which accounted for its facilitation of the N-(1-deoxy-d-xylulos-1-yl)-phenylalanine yield. The results revealed that the pH could be maintained at a relatively high level (above 7.0) for an optimized pH-buffering effect when Na 2 SO 3 (4.0%) was added before the reaction of Xyl-Phe. Thus, the conversion of Xyl-Phe to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine increased from 47.23% to 74.86%. Furthermore, the addition moment of Na 2 SO 3 and corresponding solution pH were crucial factors in regulating the pH-buffering effect of Na 2 SO 3 on N-(1-deoxy-d-xylulos-1-yl)-phenylalanine yield. Based on the pH-buffering effect of Na 2 SO 3 and maintaining the optimal pH 7.4 relatively stable, the conversion of Xyl-Phe to N-(1-deoxy-d-xylulos-1-yl)-phenylalanine was successfully improved. Copyright © 2017 Elsevier Ltd. All rights reserved.

Aldimine Formation Reaction, the First Step of the Maillard Early-phase Reaction, Might be Enhanced in Variant Hemoglobin, Hb Himeji.

PubMed

Koga, Masafumi; Inada, Shinya; Shimizu, Sayoko; Hatazaki, Masahiro; Umayahara, Yutaka; Nishihara, Eijun

2015-01-01

Hb Himeji (β140Ala→Asp) is known as a variant hemoglobin in which glycation is enhanced and HbA1c measured by immunoassay shows a high value. The phenomenon of enhanced glycation in Hb Himeji is based on the fact that the glycation product of variant hemoglobin (HbX1c) shows a higher value than HbA1c. In this study, we investigated whether aldimine formation reaction, the first step of the Maillard early-phase reaction, is enhanced in Hb Himeji in vitro. Three non-diabetic subjects with Hb Himeji and four non-diabetic subjects without variant hemoglobin were enrolled. In order to examine aldimine formation reaction, whole blood cells were incubated with 500 mg/dl of glucose at 37°C for 1 hour and were analyzed by high-performance liquid chromatography. Both HbA1c and HbX1c were not increased in this condition. After incubation with glucose, labile HbA1c (LA1c) fraction increased in the controls (1.1±0.3%). In subjects with Hb Himeji increases in the labile HbX1c (LX1c) fraction as well as the LA1c fraction were observed, and the degree of increase in the LX1c fraction was significantly higher than that of the LA1c fraction (1.8±0.1% vs. 0.5±0.2%, P<0.01). We have shown for the first time that aldimine (LX1c) formation reaction might be enhanced in Hb Himeji in vitro. The 140th amino acid in β chain of hemoglobin is suggested to be involved in aldimine formation reaction. © 2015 by the Association of Clinical Scientists, Inc.

2-Furoylmethyl amino acids as indicators of Maillard reaction during the elaboration of black garlic.

PubMed

Ríos-Ríos, Karina L; Vázquez-Barrios, M Estela; Gaytán-Martínez, Marcela; Olano, Agustín; Montilla, Antonia; Villamiel, Mar

2018-02-01

This study reports the formation of 2-furomethyl-amino acids (2-FM-AA) as indicators of Maillard reaction (MR) in black garlic elaboration, followed by the determination of furosine by ion-pair RP-HPLC-UV. The method was assessed for accuracy, repeatability and detection and quantitation limits indicating its adequacy. Traditional procedure of black garlic obtainment and the inclusion of convective drying (CDP) and ohmic heating (OHP) were assayed. For comparison purposes, three commercial black garlic samples were used. Together with furosine (2-FM-lysine), 2-furoylmethyl-γ-aminobutyric acid and 2-FM-arginine were detected. Levels of furosine were higher in CDP (46.6-110.1mg/100g protein) than in OHP (13.7-42.0mg/100g protein) samples, probably due to the most severe processing conditions used in the former. These results highlight the suitability of 2-FM-AA as chemical indicators to monitor the process of black garlic elaboration in order to obtain high quality products. Copyright © 2017 Elsevier Ltd. All rights reserved.

Role of choline and glycine betaine in the formation of N,N-dimethylpiperidinium (mepiquat) under Maillard reaction conditions.

PubMed

Bessaire, Thomas; Tarres, Adrienne; Stadler, Richard H; Delatour, Thierry

2014-01-01

This study is the first to examine the role of choline and glycine betaine, naturally present in some foods, in particular in cereal grains, to generate N,N-dimethylpiperidinium (mepiquat) under Maillard conditions via transmethylation reactions involving the nucleophile piperidine. The formation of mepiquat and its intermediates piperidine - formed by cyclisation of free lysine in the presence of reducing sugars - and N-methylpiperidine were monitored over time (240°C, up to 180 min) using high-resolution mass spectrometry in a model system comprised of a ternary mixture of lysine/fructose/alkylating agent (choline or betaine). The reaction yield was compared with data recently determined for trigonelline, a known methylation agent present naturally in coffee beans. The role of choline and glycine betaine in nucleophilic displacement reactions was further supported by experiments carried out with stable isotope-labelled precursors (¹³C- and deuterium-labelled). The results unequivocally demonstrated that the piperidine ring of mepiquat originates from the carbon chain of lysine, and that either choline or glycine betaine furnishes the N-methyl groups. The kinetics of formation of the corresponding demethylated products of both choline and glycine betaine, N,N-demethyl-2-aminoethanol and N,N-dimethylglycine, respectively, were also determined using high-resolution mass spectrometry.

Electro-activation of sweet defatted whey: Impact on the induced Maillard reaction products and bioactive peptides.

PubMed

Kareb, Ourdia; Gomaa, Ahmed; Champagne, Claude P; Jean, Julie; Aïder, Mohammed

2017-04-15

Electro-activation was used to add value to sweet defatted whey. This study aimed to investigate and to characterize the bioactive compounds formed under different electro-activation conditions by molecular and proteomic approaches. The effects of electric current intensity (400, 500 or 600mA) and whey concentration (7, 14 or 21% (w/v)) as a function of the electro-activation time (0, 15, 30 or 45min) were evaluated. The targeted dependent variables were the formation of Maillard reaction products (MRPs), protein hydrolysates and glycated compounds. It was shown that the MRPs derived from electro-activated whey at a concentration of 14% had the highest potential of biological activity. SDS-PAGE analyses indicated the formation of hydrolysates and glycated compounds with different molecular weight distributions. FTIR indicated the predominance of intermediate MRPs, such as the Schiff base compounds. LC-MS/MS and proteomics analysis showed the production of multi-functional bioactive peptides due to the hydrolysis of whey proteins. Crown Copyright © 2016. Published by Elsevier Ltd. All rights reserved.

Acute oral safety study of sodium caseinate glycosylated via maillard reaction with galactose in rats.

PubMed

Anadón, Arturo; Martínez, Maria A; Ares, Irma; Castellano, Victor; Martínez-Larrañaga, Maria R; Corzo-Martínez, Marta; Moreno, F Javier; Villamiel, Mar

2014-03-01

In order to potentially use sodium caseinate (SC) glycated with galactose (Gal) in the food industry as a new functional ingredient with proved technological and biological properties, an evaluation of oral acute toxicity has been carried out. An acute safety study with SC-Gal glycoconjugates in the Wistar rat with a single oral gavage dose of 2,000 mg/kg of body weight was conducted. The SC-Gal glycoconjugates were well tolerated; no adverse effects or mortality was observed during the 2-week observation period. No abnormal signs, behavioral changes, body weight changes, or alterations in food and water consumption occurred. After this period, no changes in hematological and serum chemistry parameters, organ weights, or gross pathology or histopathology were detected. It was concluded that SC-Gal glycoconjugates obtained via the Maillard reaction were well tolerated in rats at an acute oral dose of 2,000 mg/kg of body weight. The SC-Gal glycoconjugates have a low order of acute toxicity, and the oral 50 % lethal dose for male and female rats is in excess of 2,000 mg/kg of body weight.

Effect of ultrasound treatment on the wet heating Maillard reaction between mung bean [Vigna radiate (L.)] protein isolates and glucose and on structural and physico-chemical properties of conjugates.

PubMed

Wang, Zhongjiang; Han, Feifei; Sui, Xiaonan; Qi, Baokun; Yang, Yong; Zhang, Hui; Wang, Rui; Li, Yang; Jiang, Lianzhou

2016-03-30

The objective of this study was to determine the effect of ultrasound treatment on the wet heating Maillard reaction between mung bean protein isolates (MBPIs) and glucose, and on structural and physico-chemical properties of the conjugates. The degree of glycosylation of MBPI-glucose conjugates treated by ultrasound treatment and wet heating (MBPI-GUH) was higher than that of MBPI-glucose conjugates only treated by wet heating (MBPI-GH). Solubility, emulsification activity, emulsification stability and surface hydrophobicity of MBPI-GUH were higher than that of MBPI-GH. Grafted MBPIs had a lower content of α-helix and unordered coil, but a higher content of β-sheet and β-turn structure than MBPIs. No significant structural changes were observed in β-turn and random coil structure of MBPI-GUH, while α-helix content increased with ultrasonic time, and decreased at 300 W ultrasonic power with the increase of β-sheet. MBPI-GUH had a less compact tertiary structure compared to MBPI-GH and MBPI. Grafting MBPIs with glucose formed conjugates of higher molecular weight, while no significant changes were observed in electrophoresis profiles of MBPI-GUH. Ultrasound-assisted wet heating Maillard reaction between MBPIs and glucose could be a promising way to improve functional properties of MBPIs. © 2015 Society of Chemical Industry.

Sensory characteristics and consumer acceptability of beef stock containing the glutathione-xylose Maillard reaction product and/or monosodium glutamate.

PubMed

Hong, Jae-Hee; Kwon, Koo-Young; Kim, Kwang-Ok

2012-06-01

This study was conducted to investigate the sensory characteristics and consumer acceptability of beef stock samples containing GSH-xylose Maillard reaction product (GX) and/or monosodium glutamate (MSG) with varying levels of salt (NaCl). The sensory characteristics of the beef stock samples were examined using a descriptive analysis. Total of 50 consumers evaluated overall acceptability and flavor intensities of beef odor, salty taste, beef flavor, and seasoning flavor in the samples. Samples containing both GX and MSG (GX-MSG), GX only (GX), and GX with higher salt level (GX-NaCl) had stronger "beef odor/flavor,"sulfur odor/flavor," and "chestnut odor/flavor" than those of the other samples, whereas beef stocks containing MSG, salt only (CON), and CON with higher salt level (CON-NaCl) had stronger "potato odor/flavor" and "soy sauce odor/flavor" than those of the other samples. The consumers liked GX-MSG and MSG the most. Overall liking scores of GX-NaCl and CON-NaCl were significantly higher than that of CON. GX was not significantly preferred to CON. Partial least square regression results showed that salty, MSG, and sweet tastes had more significant impact on consumer perception of the beef and spice flavors and the liking score than strong beef odor/flavor of GX. However, high hedonic ratings of GX-MSG, which contained half the doses of GX and MSG used for the GX and MSG samples, suggest that the combination of GX and MSG had a synergistic effect on flavor enhancement of beef stock. Due to increasing needs for food products that provide more health benefits but maintain palatability, the food industry is looking for a new type of flavor enhancer. The Maillard reaction product of xylose and glutathione (GX), a tripeptide known to increase complexity and mouthfulness, was examined for its potential as a flavor enhancer. GX enhanced beef flavor significantly and salty taste somewhat at a weak suprathreshold level. With adjusting salty taste intensity by adding

Stability of Individual Maillard Reaction Products in the Presence of the Human Colonic Microbiota.

PubMed

Hellwig, Michael; Bunzel, Diana; Huch, Melanie; Franz, Charles M A P; Kulling, Sabine E; Henle, Thomas

2015-08-05

Maillard reaction products (MRPs) are taken up in substantial amounts with the daily diet, but the majority are not transported across the intestinal epithelium. The aim of this study was to obtain first insights into the stability of dietary MRPs in the presence of the intestinal microbiota. Four individual MRPs, namely, N-ε-fructosyllysine (FL), N-ε-carboxymethyllysine (CML), pyrraline (PYR), and maltosine (MAL), were anaerobically incubated with fecal suspensions from eight human volunteers at 37 °C for up to 72 h. The stability of the MRPs was measured by HPLC with UV and MS/MS detections. The Amadori product FL could no longer be detected after 4 h of incubation. Marked interindividual differences were observed for CML metabolism: Depending on the individual, at least 40.7 ± 1.5% of CML was degraded after 24 h of incubation, and the subjects could thus be tentatively grouped into fast and slow metabolizers of this compound. PYR was degraded by 20.3 ± 4.4% during 24 h by all subjects. The concentration of MAL was not significantly lowered in the presence of fecal suspensions. In no case could metabolites be identified and quantified by different mass spectrometric techniques. This is the first study showing that the human colonic microbiota is able to degrade selected glycated amino acids and possibly use them as a source of energy, carbon, and/or nitrogen.

Reduction of 5-hydroxymethylfurfural formation by flavan-3-ols in Maillard reaction models and fried potato chips.

PubMed

Qi, Yajing; Zhang, Hao; Wu, Gangcheng; Zhang, Hui; Wang, Li; Qian, Haifeng; Qi, Xiguang

2018-04-13

5-Hydroxymethylfurfural (HMF) is regarded as a thermal process contaminant in foods. Six flavan-3-ol fractions were isolated or semisynthesized from sorghum, cranberry and grape seed. Their unit compositions, interflavan linkages and degree of polymerization (DP) were characterized. The aim of this study was to investigate the effect of flavan-3-ols on the formation of HMF in chemical reaction models and fried potato chips. Results showed that all flavan-3-ols significantly mitigated the HMF formation at concentrations of 50, 100 and 200 μg mL -1 in chemical model system, and the inhibition was positively related to dose. Using the food model, HMF content was reduced by about 50% when potato chips were soaked in an optimal concentration of 0.1 mg mL -1 flavan-3-ol solutions before frying. Based on the same mass concentration, B-type flavan-3-ols mitigated more HMF than A-type, and oligomeric proanthocyanidins had stronger inhibitory activity than polymers. At suitable addition levels (0.01-0.1 mg mL -1 ), the browning of auto-oxidized flavan-3-ols under high temperature compensated the anti-browning effect along with the supressing of Maillard reaction, therefore color of fried potato chips was not affected. The present study demonstrates that flavan-3-ols could be effective addtives for reducing HMF levels in fried potato chips without changing sensory properties. This article is protected by copyright. All rights reserved.

Maillard reaction products and their relation to complications in insulin-dependent diabetes mellitus.

PubMed Central

McCance, D R; Dyer, D G; Dunn, J A; Bailie, K E; Thorpe, S R; Baynes, J W; Lyons, T J

1993-01-01

Glycation, oxidation, and browning of proteins have all been implicated in the development of diabetic complications. We measured the initial Amadori adduct, fructoselysine (FL); two Maillard products, N epsilon-(carboxymethyl) lysine (CML) and pentosidine; and fluorescence (excitation = 328 nm, emission = 378 nm) in skin collagen from 39 type 1 diabetic patients (aged 41.5 +/- 15.3 [17-73] yr; duration of diabetes 17.9 +/- 11.5 [0-46] yr, [mean +/- SD, range]). The measurements were related to the presence of background (n = 9) or proliferative (n = 16) retinopathy; early nephropathy (24-h albumin excretion rate [AER24] > or = 20 micrograms/min; n = 9); and limited joint mobility (LJM; n = 20). FL, CML, pentosidine, and fluorescence increased progressively across diabetic retinopathy (P < 0.05, P < 0.001, P < 0.05, P < 0.01, respectively). FL, CML, pentosidine, and fluorescence were also elevated in patients with early nephropathy (P < 0.05, P < 0.001, P < 0.01, P < 0.01, respectively). There was no association with LJM. Controlling for age, sex, and duration of diabetes using logistic regression, FL and CML were independently associated with retinopathy (FL odds ratio (OR) = 1.06, 95% confidence interval (CI) = 1.01-1.12, P < 0.05; CML OR = 6.77, 95% CI = 1.33-34.56, P < 0.05) and with early nephropathy (FL OR = 1.05, 95% CI = 1.01-1.10, P < 0.05; CML OR = 13.44, 95% CI = 2.00-93.30, P < 0.01). The associations between fluorescence and retinopathy and between pentosidine and nephropathy approached significance (P = 0.05). These data show that FL and Maillard products in skin correlate with functional abnormalities in other tissues and suggest that protein glycation and oxidation (glycoxidation) may be implicated in the development of diabetic retinopathy and early nephropathy. PMID:8514859

Effects of dietary bread crust Maillard reaction products on calcium and bone metabolism in rats.

PubMed

Roncero-Ramos, Irene; Delgado-Andrade, Cristina; Haro, Ana; Ruiz-Roca, Beatriz; Morales, Francisco J; Navarro, María Pilar

2013-06-01

Maillard reaction products (MRP) consumption has been related with the development of bone degenerative disorders, probably linked to changes in calcium metabolism. We aimed to investigate the effects of MRP intake from bread crust on calcium balance and its distribution, and bone metabolism. During 88 days, rats were fed control diet or diets containing bread crust as source of MRP, or its soluble high molecular weight, soluble low molecular weight or insoluble fractions (bread crust, HMW, LMW and insoluble diets, respectively). In the final week, a calcium balance was performed, then animals were sacrified and some organs removed to analyse calcium levels. A second balance was carried out throughout the experimental period to calculate global calcium retention. Biochemical parameters and bone metabolism markers were measured in serum or urine. Global calcium bioavailability was unmodified by consumption of bread crust or its isolate fractions, corroborating the previously described low affinity of MRP to bind calcium. Despite this, a higher calcium concentration was found in femur due to smaller bones having a lower relative density. The isolate consumption of the fractions altered some bone markers, reflecting a situation of increased bone resorption or higher turnover; this did not take place in the animals fed the bread crust diet. Thus, the bread crust intake does not affect negatively calcium bioavailability and bone metabolism.

Antioxidative capacity and binding affinity of the complex of green tea catechin and beta-lactoglobulin glycated by the Maillard reaction.

PubMed

Perusko, Marija; Al-Hanish, Ayah; Mihailovic, Jelena; Minic, Simeon; Trifunovic, Sara; Prodic, Ivana; Cirkovic Velickovic, Tanja

2017-10-01

Major green tea catechin, epigallocatechin-3-gallate (EGCG), binds non-covalently to numerous dietary proteins, including beta-lactoglobulin of cow's milk. The effects of glycation of proteins via Maillard reaction on the binding capacity for polyphenols and the antiradical properties of the formed complexes have not been studied previously. Binding constant of BLG glycated by milk sugar lactose to EGCG was measured by the method of fluorophore quenching. Binding of EGCG was confirmed by CD and FTIR. The antioxidative properties of the complexes were examined by measuring ABTS radical scavenging capacity, superoxide anion scavenging capacity and total reducing power assay. Glycation of BLG does not significantly influence the binding constant of EGCG for the protein. Conformational changes were observed for both native and glycated BLG upon complexation with EGCG. Masking effect of polyphenol complexation on the antioxidative potential of the protein was of the similar degree for both glycated BLG and native BLG. Copyright © 2017 Elsevier Ltd. All rights reserved.

Chemiluminescence development after initiation of Maillard reaction in aqueous solutions of glycine and glucose: nonlinearity of the process and cooperative properties of the reaction system

NASA Astrophysics Data System (ADS)

Voeikov, Vladimir L.; Naletov, Vladimir I.

1998-06-01

Nonenzymatic glycation of free or peptide bound amino acids (Maillard reaction, MR) plays an important role in aging, diabetic complications and atherosclerosis. MR taking place at high temperatures is accompanied by chemiluminescence (CL). Here kinetics of CL development in MR proceeding in model systems at room temperature has been analyzed for the first time. Brief heating of glycine and D-glucose solutions to t greater than 93 degrees Celsius results in their browning and appearance of fluorescencent properties. Developed In solutions rapidly cooled down to 20 degrees Celsius a wave of CL. It reached maximum intensity around 40 min after the reaction mixture heating and cooling it down. CL intensity elevation was accompanied by certain decoloration of the solution. Appearance of light absorbing substances and development of CL depended critically upon the temperature of preincubation (greater than or equal to 93 degrees Celsius), initial pH (greater than or equal to 11,2), sample volume (greater than or equal to 0.5 ml) and reagents concentrations. Dependence of total counts accumulation on a system volume over the critical volume was non-monotonous. After reaching maximum values CL began to decline, though only small part of glucose and glycin had been consumed. Brief heating of such solutions to the critical temperature resulted in emergence of a new CL wave. This procedure could be repeated in one and the same reaction system for several times. Whole CL kinetic curve best fitted to lognormal distribution. Macrokinetic properties of the process are characteristic of chain reactions with delayed branching. Results imply also, that self-organization occurs in this system, and that the course of the process strongly depends upon boundary conditions and periodic interference in its course.

Prenatal dietary load of Maillard reaction products combined with postnatal Coca-Cola drinking affects metabolic status of female Wistar rats

PubMed Central

Gurecká, Radana; Koborová, Ivana; Janšáková, Katarína; Tábi, Tamás; Szökő, Éva; Somoza, Veronika; Šebeková, Katarína; Celec, Peter

2015-01-01

Aim To assess the impact of prenatal exposure to Maillard reaction products (MRPs) -rich diet and postnatal Coca-Cola consumption on metabolic status of female rats. Diet rich in MRPs and consumption of saccharose/fructose sweetened soft drinks is presumed to impose increased risk of development of cardiometabolic afflictions, such as obesity or insulin resistance. Methods At the first day of pregnancy, 9 female Wistar rats were randomized into two groups, pair-fed either with standard rat chow (MRP-) or MRPs-rich diet (MRP+). Offspring from each group of mothers was divided into two groups and given either water (Cola-) or Coca-Cola (Cola+) for drinking ad libitum for 18 days. Oral glucose tolerance test was performed, and circulating markers of inflammation, oxidative stress, glucose and lipid metabolism were assessed. Results MRP+ groups had higher weight gain, significantly so in the MRP+/Cola- vs MRP-/Cola-. Both prenatal and postnatal intervention increased carboxymethyllysine levels and semicarbazide-sensitive amine oxidase activity, both significantly higher in MRP+/Cola + than in MRP-/Cola-. Total antioxidant capacity was lower in MRP+ groups, with significant decrease in MRP+/Cola + vs MRP-/Cola+. Rats drinking Coca-Cola had higher insulin, homeostatic model assessment of insulin resistance, heart rate, advanced oxidation of protein products, triacylglycerols, and oxidative stress markers measured as thiobarbituric acid reactive substances compared to rats drinking water, with no visible effect of MRPs-rich diet. Conclusion Metabolic status of rats was affected both by prenatal and postnatal dietary intervention. Our results suggest that combined effect of prenatal MRPs load and postnatal Coca-Cola drinking may play a role in development of metabolic disorders in later life. PMID:25891868

Prenatal dietary load of Maillard reaction products combined with postnatal Coca-Cola drinking affects metabolic status of female Wistar rats.

PubMed

Gurecká, Radana; Koborová, Ivana; Janšáková, Katarína; Tábi, Tamás; Szökő, Éva; Somoza, Veronika; Šebeková, Katarína; Celec, Peter

2015-04-01

To assess the impact of prenatal exposure to Maillard reaction products (MRPs) -rich diet and postnatal Coca-Cola consumption on metabolic status of female rats. Diet rich in MRPs and consumption of saccharose/fructose sweetened soft drinks is presumed to impose increased risk of development of cardiometabolic afflictions, such as obesity or insulin resistance. At the first day of pregnancy, 9 female Wistar rats were randomized into two groups, pair-fed either with standard rat chow (MRP-) or MRPs-rich diet (MRP+). Offspring from each group of mothers was divided into two groups and given either water (Cola-) or Coca-Cola (Cola+) for drinking ad libitum for 18 days. Oral glucose tolerance test was performed, and circulating markers of inflammation, oxidative stress, glucose and lipid metabolism were assessed. MRP+ groups had higher weight gain, significantly so in the MRP+/Cola- vs MRP-/Cola-. Both prenatal and postnatal intervention increased carboxymethyllysine levels and semicarbazide-sensitive amine oxidase activity, both significantly higher in MRP+/Cola + than in MRP-/Cola-. Total antioxidant capacity was lower in MRP+ groups, with significant decrease in MRP+/Cola + vs MRP-/Cola+. Rats drinking Coca-Cola had higher insulin, homeostatic model assessment of insulin resistance, heart rate, advanced oxidation of protein products, triacylglycerols, and oxidative stress markers measured as thiobarbituric acid reactive substances compared to rats drinking water, with no visible effect of MRPs-rich diet. Metabolic status of rats was affected both by prenatal and postnatal dietary intervention. Our results suggest that combined effect of prenatal MRPs load and postnatal Coca-Cola drinking may play a role in development of metabolic disorders in later life.

Modifications in bacterial groups and short chain fatty acid production in the gut of healthy adult rats after long-term consumption of dietary Maillard reaction products.

PubMed

Delgado-Andrade, Cristina; Pastoriza de la Cueva, Silvia; Peinado, M Jesús; Rufián-Henares, José Ángel; Navarro, M Pilar; Rubio, Luis A

2017-10-01

Bread crust (BC) is one of the major sources of Maillard reaction products (MRPs) in the Western diet. This work was designed to analyze the impact of diets containing important levels of MRPs from BC on intestinal bacterial growth and short chain fatty acids (SCFAs) production in adult rats. Additionally, the pools of compounds excreted in feces attending to their molecular weights were analyzed. Rats were fed for 88days a control diet or diets containing BC or its soluble high molecular weight (HMW), soluble low molecular weight (LMW) or insoluble fractions, respectively. Intestinal (cecum) microbiota composition was determined by qPCR analysis. Consumption of the BC diet lowered (P<0.05) Lactobacillus spp. and Bifidobacterium spp. log 10 counts (8 and 14%, respectively), an effect for which soluble LMW and HMW fractions of BC seemed to be responsible. In these same animals, Escherichia/Shigella counts increased by around 45% (P<0.05), a fact which correlated with a higher production of formic acid in feces (r=0.8197, P=0.0458), and likely caused by the combined consumption of all MRPs contained in the BC. A significant 5-fold increment (P<0.05) was detected in the fecal proportion of propionic acid in the BC group, one of the products that have largely been associated with anti-inflammatory actions. Regarding the distribution of MRPs in feces, only the LMW fed group exhibited a predominance of those ranging between 90,000-1000Da, whereas the rest of the groups presented higher amounts of products above 90,000Da. It is concluded that dietary Maillard reaction products are in vivo fermented by the gut microbiota, thereby changing both the pattern of SCFAs production and the microbiota composition. Copyright © 2017 Elsevier Ltd. All rights reserved.

The effect of Maillard reaction products and yeast strain on the synthesis of key higher alcohols and esters in beer fermentations.

PubMed

Dack, Rachael E; Black, Gary W; Koutsidis, Georgios; Usher, St John

2017-10-01

The effect of Maillard reaction products (MRPs), formed during the production of dark malts, on the synthesis of higher alcohols and esters in beer fermentations was investigated by headspace solid-phase microextraction GC-MS. Higher alcohol levels were significantly (p<0.05) higher in dark malt fermentations, while the synthesis of esters was inhibited, due to possible suppression of enzyme activity and/or gene expression linked to ester synthesis. Yeast strain also affected flavour synthesis with Saccharomyces cerevisiae strain A01 producing considerably lower levels of higher alcohols and esters than S288c and L04. S288c produced approximately double the higher alcohol levels and around twenty times more esters compared to L04. Further investigations into malt type-yeast strain interactions in relation to flavour development are required to gain better understanding of flavour synthesis that could assist in the development of new products and reduce R&D costs for the industry. Copyright © 2017 Elsevier Ltd. All rights reserved.

Degradations and Rearrangement Reactions

NASA Astrophysics Data System (ADS)

Zhang, Jianbo

This section deals with recent reports concerning degradation and rearrangement reactions of free sugars as well as some glycosides. The transformations are classified in chemical and enzymatic ways. In addition, the Maillard reaction will be discussed as an example of degradation and rearrangement transformation and its application in current research in the fields of chemistry and biology.

Identifying genes involved in the interaction of Aggregatibacter actinomycetemcomitans with Maillard reaction products (MRP)

NASA Astrophysics Data System (ADS)

Jaha, Raniah Abdulmohsen

Aggregatibacter (Actinobacillus) actinomycelemcomitcrns is a gram-negative bacterium that is a facultative anaerobe which can grow in either aerobic or anaerobic conditions. The bacteria cause localized aggressive periodontitis that can result in the loss of teeth and endocarditis, which is an infection of the heart valves. A rich medium is an essential requirement for its growth. There arc some difficulties associated with growing the bacteria as they easily switch from the rough to smooth phenotype under no specific conditions. The bacteria start to lose viability after about 19 hours of growth in broth or about three days on plates. Colonies in the dense part of the streak on plates die earlier. It was shown that acid secreted by the colonies is responsible for the loss of viability as the bacteria are extremely sensitive to low pH. Autoclaving the growth medium for A. actinomycetemcomitans causes the bacteria to grow slowly because of the formation of Maillard reaction products (MRPs). A method has been developed to make the A. actinomycetemcomitans growth medium using the microwave instead of the autoclave. This method produces much less of the inhibitory product since the heating time is only six minutes, compared to more than an hour when using the autoclave. Two approaches were sought in this research. The first approach was the identification of genes responsible for the interaction between the MRP and A. actinomycetemcomitans. The gene responsible for this interaction was found to be a Lys M protein which is found in many genes responsible for the cell wall integrity. The second approach was to develop a new drug made of glucose and lysine with a minimum inhibitory concentration as 75mM.

[Role of Maillard products in the chronic complications of diabetes mellitus. Bioclinical applications].

PubMed

Trivin, F

1998-01-01

The formation of Maillard products is increased in the diabetes mellitus. These advanced glycated end products (AGEs) alter metabolic functions of macromolecules and increase free radical formation while decreasing free radical-scavenging enzyme activity. The elimination of AGEs is insured by the macrophage cells equipped with appropriate receptors (RAGE) and cleared by kidneys. The knowledge of these molecular mechanisms had allowed the emergence of biochemical analytes such as 3-deoxyglucosone, pentosidine, and carboxymethyl-lysine, as markers of the ris of micro- and macro-angiopathy, the main chronic complications of the diabetes mellitus.

Chemical properties and reactive oxygen and nitrogen species quenching activities of dry sugar-amino acid maillard reaction mixtures exposed to baking temperatures.

PubMed

Chen, Xiu-Min; Liang, Ningjian; Kitts, David D

2015-10-01

Maillard reaction products (MRPs) derived from 10 different, dry sugar-amino acid reaction model systems were examined for changes in color index (E), sugar loss, and formation of α-dicarbonyl compounds; the changes were correlated with relative activities to quench both reactive oxygen (ROS) and reactive nitrogen (RNS) species. Reducing sugars, xylose, ribose, fructose, glucose, and non-reducing sucrose were reacted with glycine (Xyl-Gly, Rib-Gly, Fru-Gly, Glc-Gly, and Suc-Gly), or lysine (Xyl-Lys, Rib-Lys, Fru-Lys, Glc-Lys, and Suc-Lys), respectively, at temperatures of 150°C and 180°C for time periods ranging from 5 to 60min. ROS quenching capacity was negatively correlated with color index (E) (r=-0.604, P<0.001), and positively correlated with sugar loss (r=0.567, P<0.001). MRPs also exhibited activity to quench RNS as assessed by nitric oxide (NO) inhibition in differentiated Caco-2 cells that were induced with interferon-γ (IFN-γ) and phorbol ester (PMA) cocktail. We also showed a correlation between RNS and color index, sugar loss, and ROS quenching activities for MR mixtures that were heated for a short time (e.g. 10min) at 150°C. MRP quenching of ROS was largely influenced by sugar type, whereas, RNS quenching was dependent more so on the interaction between reactants and reaction conditions used to generate MRPs. Copyright © 2015 Elsevier Ltd. All rights reserved.

Chocolate HILIC phases: development and characterization of novel saccharide-based stationary phases by applying non-enzymatic browning (Maillard reaction) on amino-modified silica surfaces.

PubMed

Schuster, Georg; Lindner, Wolfgang

2011-06-01

Novel saccharide-based stationary phases were developed by applying non-enzymatic browning (Maillard Reaction) on aminopropyl silica material. During this process, the reducing sugars glucose, lactose, maltose, and cellobiose served as "ligand primers". The reaction cascade using cellobiose resulted in an efficient chromatographic material which further served as our model Chocolate HILIC column. (Chocolate refers to the fact that these phases are brownish.) In this way, an amine backbone was introduced to facilitate convenient manipulation of selectivity by additional attractive or repulsive ionic solute-ligand interactions in addition to the typical HILIC retention mechanism. In total, six different test sets and five different mobile phase compositions were investigated, allowing a comprehensive evaluation of the new polar column. It became evident that, besides the so-called HILIC retention mechanism based on partition phenomena, additional adsorption mechanisms, including ionic interactions, take place. Thus, the new column is another example of a HILIC-type column characterized by mixed-modal retention increments. The glucose-modified materials exhibited the relative highest overall hydrophobicity of all grafted Chocolate HILIC columns which enabled retention of lipophilic analytes with high water content mobile phases.

Maillard reaction products derived from thiol compounds as inhibitors of enzymatic browning of fruits and vegetables: the structure-activity relationship.

PubMed

Billaud, C; Maraschin, C; Peyrat-Maillard, M-N; Nicolas, J

2005-06-01

Some thiol-derived Maillard reaction products (MRPs) may exert antioxidant activity, depending on the reaction conditions as well as on the sugar and the sulphydryl compound. Recently, we reported that MRPs derived from glucose or fructose with cysteine (CSH) or glutathione (GSH) mixtures greatly inhibited polyphenoloxidases (PPOs), oxidoreductases responsible for discoloration of fresh or minimally processed fruits and vegetables. Glucose and GSH were shown to be the most active in producing inhibitory MRPs. Therefore, we examined the way in which the nature of the reactants affected their synthesis, in order to establish a structure-activity relationship for the inhibitory products. Various aqueous (0.083 M, 0.125 M, or 0.25 M) mixtures of a sugar (hexose, pentose, or diholoside) with either a CSH-related compound (CSH, GSH, N-acetyl-cysteine, cysteamine, cysteic acid, methyl-cysteine, cysteine methyl ester), an amino acid (gamma-glutamic acid, glycine, methionine), or other sulfur compound (thiourea, 1,4-dithiothreitol, 2-mercaptoethanol) were heated at 103 degrees C for 14 h. Soluble MRPs were compared for their ability to inhibit apple PPO activity. In the presence of CSH, the rated sugars (same molar concentration) ranked as to inhibitory effect were pentoses > sucrose > hexoses > or = maltose. In the presence of glucose, the simultaneous presence of an amino group, a carboxyl group, and a free thiol group on the same molecule seemed essential for the production of highly inhibitory compounds.

Effect of Maillard Conjugates on the Physical Stability of Zein Nanoparticles Prepared by Liquid Antisolvent Coprecipitation.

PubMed

Davidov-Pardo, Gabriel; Joye, Iris J; Espinal-Ruiz, Mauricio; McClements, David Julian

2015-09-30

Protein nanoparticles are often not very stable in a complex food matrix because they are primarily stabilized by electrostatic repulsion. In this study, we envisaged the stabilization of zein nanoparticles through Maillard conjugation reactions with polysaccharides of different molecular mass. Zein nanoparticles (0.5% w/v) containing resveratrol (0.025% w/v grape skin extract) were produced by liquid antisolvent precipitation and coated with Maillard conjugates (MC) of sodium caseinate and different molecular mass carbohydrates during particle production. Zein nanoparticles coated with conjugated polysaccharides of 2.8, 37, and 150 kDa had diameters of 198 ± 5, 176 ± 6, and 180 ± 3 nm, respectively. The encapsulation efficiency (∼83%) was not affected by conjugation, but the conjugates significantly improved particle stability against changes in pH (2.0-9.0), CaCl2 addition (up to 100 mM), and heat treatment (30-90 °C, 30 min). Zein nanoparticles coated by MC may therefore be suitable delivery systems for hydrophobic bioactive molecules in a wide range of commercial products.

Effects of roasting temperature and duration on fatty acid composition, phenolic composition, Maillard reaction degree and antioxidant attribute of almond (Prunus dulcis) kernel.

PubMed

Lin, Jau-Tien; Liu, Shih-Chun; Hu, Chao-Chin; Shyu, Yung-Shin; Hsu, Chia-Ying; Yang, Deng-Jye

2016-01-01

Roasting treatment increased levels of unsaturated fatty acids (linoleic, oleic and elaidic acids) as well as saturated fatty acids (palmitic and stearic acids) in almond (Prunus dulcis) kernel oils with temperature (150 or 180 °C) and duration (5, 10 or 20 min). Nonetheless, higher temperature (200 °C) and longer duration (10 or 20 min) roasting might result in breakdown of fatty acids especially for unsaturated fatty acids. Phenolic components (total phenols, flavonoids, condensed tannins and phenolic acids) of almond kernels substantially lost in the initial phase; afterward these components gradually increased with roasting temperature and duration. Similar results also observed for their antioxidant activities (scavenging DPPH and ABTS(+) radicals and ferric reducing power). The changes of phenolic acid and flavonoid compositions were also determined by HPLC. Maillard reaction products (estimated with non-enzymatic browning index) also increased with roasting temperature and duration; they might also contribute to enhancing the antioxidant attributes. Copyright © 2015 Elsevier Ltd. All rights reserved.

Antioxidant and chelating capacity of Maillard reaction products in amino acid-sugar model systems: applications for food processing.

PubMed

Mondaca-Navarro, Blanca A; Ávila-Villa, Luz A; González-Córdova, Aarón F; López-Cervantes, Jaime; Sánchez-Machado, Dalia I; Campas-Baypoli, Olga N; Rodríguez-Ramírez, Roberto

2017-08-01

Maillard reaction products (MRP) have gained increasing interest owing to their both positive and negative effects on human health. Aqueous amino acid-sugar model systems were studied in order to evaluate the antioxidant and chelating activity of MRP under conditions similar to those of food processing. Amino acids (cysteine, glycine, isoleucine and lysine) combined with different sugars (fructose or glucose) were heated to 100 and 130 °C for 30, 60 and 90 min. Antioxidant capacity was evaluated via ABTS and DPPH free radical scavenging assays, in addition to Fe 2+ and Cu 2+ ion chelating capacity. In the ABTS assay, the cysteine-fructose model system presented the highest antioxidant activity at 7.05 µmol mL -1 (130 °C, 60 min), expressed in Trolox equivalents. In the DPPH assay, the cysteine-glucose system presented the highest antioxidant activity at 3.79 µmol mL -1 (100 °C, 90 min). The maximum rate of chelation of Fe 2+ and Cu 2+ was 96.31 and 59.44% respectively in the lysine-fructose and cysteine-glucose systems (100 °C, 30 min). The model systems presented antioxidant and chelating activity under the analyzed temperatures and heating times, which are similar to the processing conditions of some foods. © 2017 Society of Chemical Industry. © 2017 Society of Chemical Industry.

Chemical properties of commercially available honey species and the functional properties of caramelization and Maillard reaction products derived from these honey species.

PubMed

Nagai, T; Kai, N; Tanoue, Y; Suzuki, N

2018-02-01

The chemical parameters and the functionalities of six monofloral honeys of different botanical and geographical origins were investigated. Vitamins B 1 , B 2 , and C and the protein content of majority of honeys were distinguishable from general honey. Honeys not only were rich in a variety of functional components like flavonoids but also had strong anti-oxidant activities, scavenging activities against ROS, and anti-hypertensive and anti-allergic activities. Honeys were heated at 100 °C for 24 h and their browning intensity during heating process was observed to vary with botanical origin. The functional properties of caramelization and maillard reaction (MR) products derived from honeys during heating were evaluated. The browning of honeys progressed regardless of honey species. Anti-oxidant activities and scavenging activities against superoxide and DPPH radicals of products drastically increased, but ACE and hyaluronidase activities gradually decreased with passage of heating time. It concluded that the products, mainly melanoidins, produced simultaneously to browning process in caramelization and MR contributed to the expression of its useful function.

Formation of the reduced form of furaneol® (2,5-dimethyl-4-hydroxy-tetrahydrofuran-3-one) during the Maillard reaction through catalysis of amino acid metal salts.

PubMed

Nashalian, Ossanna; Wang, Xi; Yaylayan, Varoujan A

2016-11-01

Under pyrolytic conditions the acidity/basicity of Maillard reaction mixtures can be controlled through the use of hydrochloride or sodium salts of amino acids to generate a diversity of products. When the degradation of glucose was studied under pyrolytic conditions using excess sodium glycinate the reaction was found to generate a major unknown peak having a molecular ion at m/z 130. Subsequent in-depth isotope labelling studies indicated that acetol was an important precursor of this compound under pyrolytic and aqueous heating conditions. The dimerisation and cyclisation of acetol into 2,5-dimethyl-4-hydroxy-tetrahydrofuran-3-one was found to be catalysed by amino acid metal salts. Also, ESI/qTOF/MS studies indicated that the unknown peak has expected molecular formula of C6H10O3. Finally, a peak having the same retention time and mass spectrum was also generated pyrolytically when furaneol® was reduced with NaBH4 confirming the initial hypothesis regarding the unknown peak to be the reduced form of furaneol®. Copyright © 2016 Elsevier Ltd. All rights reserved.

Testing isotopic labeling with [¹³C₆]glucose as a method of advanced glycation sites identification.

PubMed

Kielmas, Martyna; Kijewska, Monika; Stefanowicz, Piotr; Szewczuk, Zbigniew

2012-12-01

The Maillard reaction occurring between reducing sugars and reactive amino groups of biomolecules leads to the formation of a heterogeneous mixture of compounds: early, intermediate, and advanced glycation end products (AGEs). These compounds could be markers of certain diseases and of the premature aging process. Detection of Amadori products can be performed by various methods, including MS/MS techniques and affinity chromatography on immobilized boronic acid. However, the diversity of the structures of AGEs makes detection of these compounds more difficult. The aim of this study was to test a new method of AGE identification based on isotope (13)C labeling. The model protein (hen egg lysozyme) was modified with an equimolar mixture of [(12)C(6)]glucose and [(13)C(6)]glucose and then subjected to reduction of the disulfide bridges followed by tryptic hydrolysis. The digest obtained was analyzed by LC-MS. The glycation products were identified on the basis of characteristic isotopic patterns resulting from the use of isotopically labeled glucose. This method allowed identification of 38 early Maillard reaction products and five different structures of the end glycation products. This isotopic labeling technique combined with LC-MS is a sensitive method for identification of advanced glycation end products even if their chemical structure is unknown. Copyright © 2012 Elsevier Inc. All rights reserved.

Discovery and structure determination of a novel Maillard-derived sweetness enhancer by application of the comparative taste dilution analysis (cTDA).

PubMed

Ottinger, Harald; Soldo, Tomislav; Hofmann, Thomas

2003-02-12

Application of a novel screening procedure, the comparative taste dilution analysis (cTDA), on the non-solvent-extractable reaction products formed in a thermally processed aqueous solution of glucose and l-alanine led to the discovery of the presence of a sweetness-enhancing Maillard reaction product. Isolation, followed by LC-MS and 1D- and 2D-NMR measurements, and synthesis led to its unequivocal identification as N-(1-carboxyethyl)-6-(hydroxymethyl)pyridinium-3-ol inner salt. This so-called alapyridaine, although being tasteless itself, is the first nonvolatile, sweetness-enhancing Maillard reaction product reported in the literature. Depending on the pH value, the detection thresholds of sweet sugars, amino acids, and aspartame, respectively, were found to be significantly decreased when alapyridaine was present; for example, the threshold of glucose decreased by a factor of 16 in an equimolar mixture of glucose and alapyridaine. Studies on the influence of the stereochemistry on taste-enhancing activity revealed that the (+)-(S)-alapyridaine is the physiologically active enantiomer, whereas the (-)-(R)-enantiomer did not affect sweetness perception at all. Thermal processing of aqueous solutions of alapyridaine at 80 degrees C demonstrated a high thermal and hydrolytic stability of that sweetness enhancer; for example, more than 90 or 80% of alapyridaine was recovered when heated for 5 h at pH 7.0, 5.0, or 3.0, respectively.

The impact of raw materials and baking conditions on Maillard reaction products, thiamine, folate, phytic acid and minerals in white bread.

PubMed

Helou, Cynthia; Gadonna-Widehem, Pascale; Robert, Nathalie; Branlard, Gérard; Thebault, Jacques; Librere, Sarah; Jacquot, Sylvain; Mardon, Julie; Piquet-Pissaloux, Agnès; Chapron, Sophie; Chatillon, Antoine; Niquet-Léridon, Céline; Tessier, Frédéric J

2016-06-15

The aim of this study was to develop a white bread with improved nutrient contents and reduced levels of potentially harmful Maillard reaction products such as N(ε)-carboxymethyllysine (CML) and 5-hydroxymethylfurfural (HMF). Assays were carried out through a full factorial experimental design allowing the simultaneous analysis of four factors at two levels: (1) wheat flour extraction rates (ash content: 0.60%-0.72%), (2) leavening agents (bakers' yeast - bakers' yeast and sourdough), (3) prebaking and (4) baking conditions (different sets of time and temperature). The baking conditions affected HMF and CML as well as certain mineral contents. A reduced baking temperature along with a prolonged heat treatment was found to be favourable for reducing both the CML (up to 20%) and HMF concentrations (up to 96%). The presence of sourdough decreased the formation of CML (up to 28%), and increased the apparent amounts of calcium (up to 8%) and manganese (up to 17.5%) probably through acidification of the dough. The extraction rate of flours as well as interactions between multiple factors also affected certain mineral content. However, compounds like folate, thiamine, copper, zinc, iron and phytic acid were not affected by any of the factors studied.

Assessment of protein quality of soybean meal and 00-rapeseed meal toasted in the presence of lignosulfonate by amino acid digestibility in growing pigs and Maillard reaction products.

PubMed

Hulshof, T G; Bikker, P; van der Poel, A F B; Hendriks, W H

2016-03-01

An experiment was conducted to determine protein quality in processed protein sources using the content of AA, -methylisourea (OMIU)-reactive Lys, Maillard reaction products (MRP), and cross-link products; the standardized ileal digestibility (SID) of CP and AA; and growth performance in growing pigs as criteria. Differences in protein quality were created by secondary toasting (at 95°C for 30 min) of soybean meal (SBM) and rapeseed meal (RSM) in the presence of lignosulfonate resulting in processed SBM (pSBM) and processed RSM (pRSM). The processing treatment was used as a model for overprocessed protein sources. Ten growing pigs were each fed 1 of the 4 diets containing SBM, pSBM, RSM, or pRSM in each of 3 periods. Ileal chyme was collected at the end of each period and analyzed for CP, AA, and OMIU-reactive Lys. Diets were analyzed for furosine and carboxymethyllysine (CML) as an indicator for MRP and lysinoalanine (LAL), which is a cross-link product. The SBM and RSM diets contained furosine, CML, and LAL, indicating that the Maillard reaction and cross-linking had taken place in SBM and RSM, presumably during the oil extraction/desolventizing process. The amounts of furosine, CML, and LAL were elevated in pSBM and pRSM due to further processing. Processing resulted in a reduction in total and OMIU-reactive Lys contents and a decrease in G:F from 0.52 to 0.42 for SBM and 0.46 to 0.39 for RSM ( = 0.006), SID of CP from 83.9 to 71.6% for SBM and 74.9 to 64.6% for RSM ( < 0.001), and SID of AA ( < 0.001), with the largest effects for total and OMIU-reactive Lys. The effects of processing could be substantial and should be taken into account when using processed protein sources in diets for growing pigs. The extent of protein damage may be assessed by additional analyses of MRP and cross-link products.

Role of pyridoxamine in the formation of the Amadori/Heyns compounds and aggregates during the glycation of beta-lactoglobulin with galactose and tagatose.

PubMed

Corzo-Martínez, Marta; Moreno, F Javier; Olano, Agustín; Villamiel, Mar

2010-01-13

The effect of pyridoxamine on the Maillard reaction during the formation of conjugates of beta-lactoglobulin with galactose and tagatose under controlled conditions (pH 7, 0.44 aw, 40 and 50 degrees C, for 6 days) has been studied, for the first time, by means of the changes in reducing carbohydrates, formation of Amadori or Heyns compounds, and aggregates and browning development. The results showed the formation of interaction products between pyridoxamine and galactose or tagatose either in the presence or in the absence of beta-lactoglobulin, indicating that pyridoxamine competes with the free amino groups of beta-lactoglobulin for the carbonyl group of both carbohydrates. Thus, a small inhibitory effect of pyridoxamine on the initial stages of the Maillard reaction was pointed out. Furthermore, much lower aggregation and color formation rates were observed in the conjugates of beta-lactoglobulin galactose/tagatose with pyridoxamine than without this compound, supporting its potent inhibitory effect on the advanced and final stages of the Maillard reaction. These findings reveal the usefulness of food-grade inhibitors of the advanced stages of the Maillard reaction, such as pyridoxamine, that, in combination with mild storage conditions, could lead to the formation of safer neoglycoconjugates without impairing their nutritional quality.

Physicochemical Changes and Glycation Reaction in Intermediate-Moisture Protein-Sugar Foods with and without Addition of Resveratrol during Storage.

PubMed

Sheng, Zhanwu; Gu, Mantun; Hao, Wangjun; Shen, Yixiao; Zhang, Weimin; Zheng, Lili; Ai, Binling; Zheng, Xiaoyan; Xu, Zhimin

2016-06-22

An intermediate-moisture food (IMF) model consisting of whey protein isolate and glucose and an IMF model fortified with resveratrol were used to study the effect of resveratrol on physicochemical changes and glycation of protein-sugar-rich foods during storage. The water activity (aw) of the storage was controlled at 0.75 or 0.56. The browning rate or hardness of fortified IMFs was significantly lower than that of IMFs after 45-day storage. The rate of Maillard reaction in the samples stored at aw 0.56 was higher than that of samples stored at aw 0.75. The fortified IMFs had lower levels of AGEs (advanced glycation end products), CML (N(ε)-(carboxymethyl)-l-lysine), and insoluble protein during storage. The inhibition capability of resveratrol against glycation was also confirmed by using sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS-PAGE), liquid chromatography mass spectrometry (LC-MS), and Fourier transform infrared spectroscopy (FTIR) analysis to monitor glycated proteins and protein aggregation in the samples. The results of this study suggested that resveratrol could be used as an inhibitor to reduce the formation of undesirable AGEs and other Maillard reaction products in foods during storage.

Effects of sterilization, packaging, and storage on vitamin C degradation, protein denaturation, and glycation in fortified milks.

PubMed

Gliguem, H; Birlouez-Aragon, I

2005-03-01

Monitoring the nutritional quality of dietetic milk throughout its shelf life is particularly important due to the high susceptibility of some vitamins to oxidation, and the continuous development of the Maillard reaction during storage. The objective of this paper was to evaluate the vitamin C content and protein modification by denaturation and glycation on fortified milk samples (growth milks) destined for 1- to 3-yr-old children. The influences of the sterilization process, formulation, packaging, and storage duration at ambient temperature in the dark were studied. Vitamin C degradation was particularly influenced by type of packaging. The use of a 3-layered opaque bottle was associated with complete oxidation of vitamin C after 1 mo of storage, whereas in the 6-layered opaque bottle, which has an oxygen barrier, the vitamin C content slowly decreased to reach 25% of the initial concentration after 4 mo of storage. However, no significant effect of vitamin C degradation during storage could be observed in terms of Maillard reaction, despite the fact that a probable impact occurred during sterilization. Furosine content and the FAST (fluorescence of advanced Maillard products and soluble tryptophan) index-indicators of the early and advanced Maillard reaction, respectively-were significantly higher in the in-bottle sterilized milk samples compared with UHT samples, and in fortified milk samples compared with cow milk. However, after 1 mo, the impact of storage was predominant, increasing the furosine level and the FAST index at similar levels for the differently processed samples. The early Maillard reaction developed continuously throughout the storage period.In conclusion, only packaging comprising an oxygen and light barrier is compatible with vitamin C fortification of milk. Furthermore, short storage time or low storage temperature is needed to retard vitamin C degradation, protein denaturation, and development of the Maillard reaction.

Control of Maillard-type off-flavor development in ultrahigh-temperature-processed bovine milk by phenolic chemistry.

PubMed

Kokkinidou, Smaro; Peterson, Devin G

2014-08-13

The application of phenolic compounds to suppress Maillard chemistry and off-flavor development in ultrahigh-termperature (UHT)-processed milk during processing and storage was investigated. Five phenolic compounds were examined for structure-reactivity relationships (catechin, genistein, daidzein, 1,2,3-trihydroxybenzene, and 1,3,5-trihydroxybenzene). The levels of key transient Maillard reaction (MR) intermediates (reactive carbonyl species) and select off-flavor markers (methional, 2-acetyl-2-thiazoline, 2-acetyl-1-pyrroline) were quantified by LC-MS/MS and GC-MS/ToF, respectively. The addition of phenolic compounds prior to UHT processing significantly reduced the concentration of MR intermediates and related off-flavor compounds compared to a control sample (p < 0.05). All phenolic compounds demonstrated unique structure reactivity and, notably, those with a more activated A-ring for aromatic electrophilic substitution (catechin, genistein, and 1,3,5-trihydroxybenzene) showed the strongest suppression effect on the off-flavor markers and reactive carbonyl species. Sensory studies were in agreement with the analytical data. The cooked flavor intensity was rated lower for the recombination model samples of the catechin-treated UHT milk compared to the control UHT milk. Additionally, consumer acceptability studies showed catechin-treated UHT milk to have significantly higher liking scores when compared the control sample (Fisher's LSD = 0.728).

Drugs of abuse that mediate advanced glycation end product formation: a chemical link to disease pathology.

PubMed

Treweek, Jennifer B; Dickerson, Tobin J; Janda, Kim D

2009-05-19

Nicotine and methamphetamine are frequently abused in modern society, despite the increasing evidence of their addictive, neuropharmacological, and toxic effects. Tobacco, the most widely abused substance, is the leading cause of preventable death in the United States, killing nearly half a million Americans annually. A methamphetamine epidemic has also spread during the past decade; severe neurotoxicity and addictiveness contribute to the drug's notoriety. Although the majority of research on these two drugs is of pharmacological and neurobiological motivation, further study of these molecules from a chemical perspective may provide novel mechanistic insight into either their addictive potential or their pathological effects. For example, nicotine and methamphetamine share a common structural feature, a secondary amine, suggesting that these molecules could possess similar (or analogous) in vivo reactivity. Discoveries concerning the synthetic requirements for aqueous aldol catalysis and the feasibility of the enamine mechanism under physiological conditions have given rise to the hypothesis that ingested molecules, such as abused drugs, could participate in reactions utilizing an enamine intermediate in vivo. The chemical reactivity of exogenous drugs with amine functionalities was initially examined in the context of the Maillard reaction, or nonenzymatic browning. The heating of reducing sugars with amino acids yields a brown solution; studies of this reaction were originally applied to food chemistry for the production of distinct flavors and aromas. Further research has since revealed numerous instances in which the in vivo production of advanced glycation end products (AGEs) through the Maillard reaction contribute to the pathology of disease states. Specifically, the modification of long-lived proteins by glycation and glycoxidation and the accumulation of these AGEs compromise the original function of such proteins and change the mechanical properties of

Maillard neoglycans as inhibitors for in vitro adhesion of F4+ enterotoxigenic Escherichia coli to piglet intestinal cells.

PubMed

Sarabia-Sainz, Héctor Manuel; Mata Haro, Verónica; Sarabia Sainz, José Andre-I; Vázquez-Moreno, Luz; Montfort, Gabriela Ramos-Clamont

2017-01-01

Adhesion of enterotoxigenic (ETEC) E. coli to host intestinal cells is mediated by lectin-like fimbriae that bind to specific glycan moieties on the surfaces of enterocytes. To prevent in vitro binding of E. coli F4 fimbriae (F4 ETEC + ) to piglet enterocytes, neoglycans were synthesized by the Maillard reaction conjugating lactose (Lac), galacto-oligosaccharides (GOS) or chitin oligosaccharides (Ochit) to porcine serum albumin (PSA). Neoglycans were characterized by SDS-PAGE, intrinsic tryptophan fluorescence and recognition by plant lectins, as well as by F4 ETEC variants. Electrophoretic patterns suggested the binding to PSA of 63, 13 and 2 molecules of Lac, GOS and Ochit, respectively. All neoglycans displayed quenching of tryptophan fluorescence consistent with the degree of glycation estimated by SDS-PAGE. Plant lectins recognized the neoglycans according to their specificity, whereas antigenic variants of F4 ETEC (ab, ac and ad) recognized PSA-Ochit and PSA-Lac with higher affinity than that for GOS. Neoglycans partially hindered the in vitro binding of F4 + ETEC to piglet enterocytes in a dose-dependent manner. The most effective blocking was observed with PSA-Lac that partially inhibited the adhesion of bacteria to enterocytes in a dose dependent manner, as quantified by flow cytometry. Increased production of the cytokines IL-6 and TNF-α was observed in response to F4 + ETEC infection of enterocytes and production was reduced in the presence of PSA-Ochit and PSA-GOS. These results suggest that neoglycans synthesized by the Maillard reaction could be useful in the prophylaxis of diarrhea in piglets.

Generation of Maillard compounds from inulin during the thermal processing of Agave tequilana Weber Var. azul.

PubMed

Mancilla-Margalli, Norma A; López, Mercedes G

2002-02-13

During the cooking process of Agave tequilana Weber var. azul to produce tequila, besides the hydrolysis of inulin to generate fermentable sugars, many volatiles, mainly Maillard compounds, are produced, most of which may have a significant impact on the overall flavor of tequila. Exudates (agave juice) from a tequila company were collected periodically, and color, Brix, fructose concentration, and reducing sugars were determined as inulin breakdown took place. Maillard compounds were obtained by extraction with CH(2)Cl(2), and the extracts were analyzed by GC-MS. Increments in color, Brix, and reducing sugars were observed as a function of time, but a decrease in fructose concentration was found. Many Maillard compounds were identified in the exudates, including furans, pyrans, aldehydes, and nitrogen and sulfur compounds. The most abundant Maillard compounds were methyl-2-furoate, 2,3-dihydroxy-3,5-dihydro-6-methyl-4(H)-pyran-4-one, and 5-(hydroxymethyl)furfural. In addition, a series of short- and long-chain fatty acids was also found. A large number of the volatiles in A. tequilana Weber var. azul were also detected in tequila extracts, and most of these have been reported as a powerful odorants, responsible for the unique tequila flavor.

Possibility of the Nonenzymatic Browning (Maillard) Reaction in the ISM

NASA Astrophysics Data System (ADS)

Jalbout, Abraham F.; Shipar, M. Abul Haider

2008-04-01

The possibility of the occurrence of the nonenzymatic browning reaction in the gaseous phase in the interstellar medium has been investigated by using Density Functional Theory computations. Mechanisms for the reactions between formaldehyde ( Fald) + glycine ( Gly), Fald + NH 3 and Fald + methylamine ( MeAm) have been proposed, and the possibility of the formation of different compounds in the proposed mechanisms has been evaluated through calculating the Gibb's free energy changes for different steps of the reaction, by following the total mass balance. The Fald + Gly reaction under basic conditions is found as the most favorable for producing 1-methyl-amino methene or 1-methyl-amino methelene ( MAM). The reaction under acidic conditions is found to be the least favorable for producing MAM. The Fald + NH 3 reaction is found to be plausible for the production of MeAm, which can participate by reaction with Fald, resulting in the formation of MAM.

Maillard reaction versus other nonenzymatic modifications in neurodegenerative processes.

PubMed

Pamplona, Reinald; Ilieva, Ekaterina; Ayala, Victoria; Bellmunt, Maria Josep; Cacabelos, Daniel; Dalfo, Esther; Ferrer, Isidre; Portero-Otin, Manuel

2008-04-01

Nonenzymatic protein modifications are generated from direct oxidation of amino acid side chains and from reaction of the nucleophilic side chains of specific amino acids with reactive carbonyl species. These reactions give rise to specific markers that have been analyzed in different neurodegenerative diseases sharing protein aggregation, such as Alzheimer's disease, Pick's disease, Parkinson's disease, dementia with Lewy bodies, Creutzfeldt-Jakob disease, and amyotrophic lateral sclerosis. Collectively, available data demonstrate that oxidative stress homeostasis, mitochondrial function, and energy metabolism are key factors in determining the disease-specific pattern of protein molecular damage. In addition, these findings suggest the lack of a "gold marker of oxidative stress," and, consequently, they strengthen the need for a molecular dissection of the nonenzymatic reactions underlying neurodegenerative processes.

Conceptual study on maillardized dietary fiber in coffee.

PubMed

Silván, José Manuel; Morales, Francisco J; Saura-Calixto, Fulgencio

2010-12-08

There is a methodological and conceptual overlap between coffee melanoidins and dietary fiber. Green Uganda coffee beans were roasted in a range from 8.1 to 21.6% of weight loss to evaluate melanoidins and dietary fiber. Samples were characterized by color, moisture, solubility, water activity, carbohydrates, polyphenols, protein, soluble dietary fiber (SDF), and melanoidins content. Hydroxymethylfurfural and chlorogenic acids were also measured as chemical markers of the extent of roasting. Melanoidins rapidly increased from 5.6 (light roasting) to 29.1 mg/100 mg soluble dry matter (dark roasting). A melanoidins-like structure was already present in green coffee that might overestimate up to 21.0% of the melanoidins content as determined by colorimetric methods. However, its contribution is variable and very likely depends on the method of drying applied to green coffee. SDF content (mg/100 mg soluble dry matter) gradually increased from 39.4 in green coffee to 64.9 at severe roasting conditions due to incorporation of neoformed colored structures and polyphenols. Then, SDF progressively turns to a maillardized structure, which increased from 11.0 to 45.0% according to the roasting conditions. It is concluded that the content of coffee melanoidins includes a substantial part of dietary fiber and also that coffee dietary fiber includes melanoidins. A conceptual discussion on a new definition of coffee melanoidins as a type of maillardized dietary fiber is conducted.

Non-enzymatic-browning-reaction: a versatile route for production of nitrogen-doped carbon dots with tunable multicolor luminescent display.

PubMed

Wei, Weili; Xu, Can; Wu, Li; Wang, Jiasi; Ren, Jinsong; Qu, Xiaogang

2014-01-06

The non-enzymatic browning, namely Maillard reaction is commonly invoked to account for abiotic chemical transformations of organic matter. Here we report a new reaction pathway via the Maillard reaction to systematically synthesize a series of nitrogen-doped carbon dots (C-dots) with superhigh quantum yield (QY) and tunable multicolor luminescent displayment. The starting materials are glucose and the serial amino acid analogues which allow systemically controlling luminescent and physicochemical properties of C-dots at will. Unexpectedly, the as-prepared C-dots possess bright photoluminescence with QY up to 69.1% which is almost the highest ever reported, favorable biocompatibility, excellent aqueous and nonaqueous dispersibility, ultrahigh photostability, and readily functionalization. We have demonstrated that they are particularly suitable for multicolor luminescent display and long-term and real-time cellular imaging. Furthermore, the methodology is readily scalable to large yield, and can provide sufficient amount of C-dots for practical demands.

Non-Enzymatic-Browning-Reaction: A Versatile Route for Production of Nitrogen-Doped Carbon Dots with Tunable Multicolor Luminescent Display

NASA Astrophysics Data System (ADS)

Wei, Weili; Xu, Can; Wu, Li; Wang, Jiasi; Ren, Jinsong; Qu, Xiaogang

2014-01-01

The non-enzymatic browning, namely Maillard reaction is commonly invoked to account for abiotic chemical transformations of organic matter. Here we report a new reaction pathway via the Maillard reaction to systematically synthesize a series of nitrogen-doped carbon dots (C-dots) with superhigh quantum yield (QY) and tunable multicolor luminescent displayment. The starting materials are glucose and the serial amino acid analogues which allow systemically controlling luminescent and physicochemical properties of C-dots at will. Unexpectedly, the as-prepared C-dots possess bright photoluminescence with QY up to 69.1% which is almost the highest ever reported, favorable biocompatibility, excellent aqueous and nonaqueous dispersibility, ultrahigh photostability, and readily functionalization. We have demonstrated that they are particularly suitable for multicolor luminescent display and long-term and real-time cellular imaging. Furthermore, the methodology is readily scalable to large yield, and can provide sufficient amount of C-dots for practical demands.

Free Maillard Reaction Products in Milk Reflect Nutritional Intake of Glycated Proteins and Can Be Used to Distinguish "Organic" and "Conventionally" Produced Milk.

PubMed

Schwarzenbolz, Uwe; Hofmann, Thomas; Sparmann, Nina; Henle, Thomas

2016-06-22

Using LC-MS/MS and isotopically labeled standard substances, quantitation of free Maillard reaction products (MRPs), namely, N(ε)-(carboxymethyl)lysine (CML), 5-(hydroxymethyl)-1H-pyrrole-2-carbaldehyde (pyrraline, PYR), N(δ)-(5-hydro-5-methyl-4-imidazolon-2-yl)-ornithine (MG-H), and N(ε)-fructosyllysine (FL), in bovine milk was achieved. Considerable variations in the amounts of the individual MRPs were found, most likely as a consequence of the nutritional uptake of glycated proteins. When comparing commercial milk samples labeled as originating from "organic" or "conventional" farming, respectively, significant differences in the content of free PYR (organic milk, 20-300 pmol/mL; conventional milk, 400-1000 pmol/mL) were observed. An analysis of feed samples indicated that rapeseed and sugar beet are the main sources for MRPs in conventional farming. Furthermore, milk of different dairy animals (cow, buffalo, donkey, goat, ewe, mare, camel) as well as for the first time human milk was analyzed for free MRPs. The distribution of their concentrations, with FL and PYR as the most abundant in human milk and with a high individual variability, also points to a nutritional influence. As the components of concentrated feed do not belong to the natural food sources of ruminants and equidae, free MRPs in milk might serve as indicators for an adequate animal feeding in near-natural farming and can be suitable parameters to distinguish between an "organic" and "conventional" production method of milk.

Influence of thermally processed carbohydrate/amino acid mixtures on the fermentation by Saccharomyces cerevisiae.

PubMed

Tauer, Andreas; Elss, Sandra; Frischmann, Matthias; Tellez, Patricia; Pischetsrieder, Monika

2004-04-07

The production of alcoholic beverages such as Tequila, Mezcal, whiskey, or beer includes the fermentation of a mash containing Maillard reaction products. Because excessive heating of the mash can lead to complications during the following fermentation step, the impact of Maillard products on the metabolism of Saccharomyces cerevisiae was investigated. For this purpose, fermentation was carried out in a model system in the presence and absence of Maillard reaction products and formation of ethanol served as a marker for the progression of fermentation. We found that increasing amounts of Maillard products reduced the formation of ethanol up to 80%. This effect was dependent on the pH value during the Maillard reaction, reaction time, as well as the carbohydrate and amino acid component used for the generation of Maillard reaction products. Another important factor is the pH value during fermentation: The inhibitory effect of Maillard products was not detectable at a pH of 4 and increased with higher pH-values. These findings might be of relevance for the production of above-mentioned beverages.

Aerosol-Forming Reactions of Glyoxal, Methylglyoxal and Amino Acids in Clouds

NASA Astrophysics Data System (ADS)

de Haan, D. O.; Smith, K. W.; Stroik, D. R.; Corrigan, A. L.; Lee, F. E.; Phan, J. T.; Conley, A. C.

2008-12-01

Glyoxal and methylglyoxal are two common aldehydes present in fog and cloud water. Amino acids are present in clouds at similar concentrations. Here we present bulk and aerosol mass spectroscopic data demonstrating that irreversible reactions between glyoxal and amino acids, triggered by droplet evaporation, produce N-derivatized imidazole compounds along with deeply colored Maillard reaction products. These reactions can occur in the dark and in the absence of oxidants. Reactions between methylglyoxal and amino acids produce analogous methylated products plus oligomers with masses up to m/z = 1000. These reactions, which go to completion on the 10-min-timescale of cloud processing, could be significant sources of secondary organic aerosol and humic-like substances (HULIS or brown carbon).

Advanced glycation endproducts form during ovalbumin digestion in the presence of fructose: Inhibition by chlorogenic acid.

PubMed

Bains, Yasmin; Gugliucci, Alejandro; Caccavello, Russell

2017-07-01

One mechanism by which fructose could exert deleterious effects is through intestinal formation and absorption of pro-inflammatory advanced glycation endproducts via the Maillard reaction. We employed simulated stomach and duodenum digestion of ovalbumin (OVA) to test the hypothesis that advanced glycation endproducts (AGEs) are formed by fructose during simulated digestion of a ubiquitous food protein under model physiological conditions. OVA was subjected to simulated gastric and intestinal digestion using standard models, in presence of fructose or glucose (0-100mM). Peptide fractions were analyzed by fluorescence spectroscopy and intensity at Excitation: λ370nm, Emission: λ 440nm. AGE adducts formed between fructose and OVA, evidenced by the peptide fractions (<5kDa) at times (30min) and concentration ranges (10mM) plausibly found in the intestines, whereas no reaction occurs with glucose. The reaction was inhibited by chlorogenic acid at concentrations compatible with those found in the gut. The reaction was also inhibited by aminoguanidine, a specific antiglycation agent. Our study showed fructose-AGE formation on a ubiquitous dietary protein under model physiological conditions. Our study also suggests ways to decrease the damage: enteral fructose-AGE formation may be partially inhibited by co-intake of beverages, fruits and vegetables with concentrations of phenolics high enough to serve as anti-glycation agents. Copyright © 2017 Elsevier B.V. All rights reserved.

Modelling the Maillard reaction during the cooking of a model cheese.

PubMed

Bertrand, Emmanuel; Meyer, Xuân-Mi; Machado-Maturana, Elizabeth; Berdagué, Jean-Louis; Kondjoyan, Alain

2015-10-01

During processing and storage of industrial processed cheese, odorous compounds are formed. Some of them are potentially unwanted for the flavour of the product. To reduce the appearance of these compounds, a methodological approach was employed. It consists of: (i) the identification of the key compounds or precursors responsible for the off-flavour observed, (ii) the monitoring of these markers during the heat treatments applied to the cheese medium, (iii) the establishment of an observable reaction scheme adapted from a literature survey to the compounds identified in the heated cheese medium (iv) the multi-responses stoichiokinetic modelling of these reaction markers. Systematic two-dimensional gas chromatography time-of-flight mass spectrometry was used for the semi-quantitation of trace compounds. Precursors were quantitated by high-performance liquid chromatography. The experimental data obtained were fitted to the model with 14 elementary linked reactions forming a multi-response observable reaction scheme. Copyright © 2015 Elsevier Ltd. All rights reserved.

Recent Advances in the Pauson-Khand Reaction.

PubMed

Ricker, J David; Geary, Laina M

2017-06-01

The Pauson-Khand [2+2+1] cycloaddition of alkynes, alkenes, and carbon monoxide has been a vibrant area of research for more than 40 years. This review highlights recent achievements in the Pauson-Khand reaction, particularly in catalytic and asymmetric variants. Discussion of regioselectivity and advances in substrate scope is also presented.

Structured fluids as microreactors for flavor formation by the Maillard reaction.

PubMed

Vauthey, S; Milo, C; Frossard, P; Garti, N; Leser, M E; Watzke, H J

2000-10-01

Thermal reactions of cysteine/furfural and cysteine/ribose mixtures were studied in model systems to gain more insight into the influence of structured fluids such as L(2) microemulsions and cubic phases on the generation of aroma compounds. Formation of 2-furfurylthiol from cysteine/furfural was particularly efficient in L(2) microemulsions and cubic phases compared to aqueous systems. The reaction led to the formation of two new sulfur compounds, which were identified as 2-(2-furyl)thiazolidine and, tentatively, N-(2-mercaptovinyl)-2-(2-furyl)thiazolidine. Similarly, generation of 2-furfurylthiol and 2-methyl-3-furanthiol from cysteine/ribose mixtures was strongly enhanced in structured fluids. The cubic phase was shown to be even more efficient in flavor generation than the L(2) microemulsion. It was denoted "cubic catalyst" or "cubic selective microreactor". The obtained results are interpreted in terms of a surface and curvature control of the reactions defined by the structural properties of the formed surfactant associates.

Volatile fingerprints of seeds of four species indicate the involvement of alcoholic fermentation, lipid peroxidation, and Maillard reactions in seed deterioration during ageing and desiccation stress

PubMed Central

Colville, Louise

2012-01-01

The volatile compounds released by orthodox (desiccation-tolerant) seeds during ageing can be analysed using gas chromatography–mass spectrometry (GC-MS). Comparison of three legume species (Pisum sativum, Lathyrus pratensis, and Cytisus scoparius) during artificial ageing at 60% relative humidity and 50 °C revealed variation in the seed volatile fingerprint between species, although in all species the overall volatile concentration increased with storage period, and changes could be detected prior to the onset of viability loss. The volatile compounds are proposed to derive from three main sources: alcoholic fermentation, lipid peroxidation, and Maillard reactions. Lipid peroxidation was confirmed in P. sativum seeds through analysis of malondialdehyde and 4-hydroxynonenal. Volatile production by ageing orthodox seeds was compared with that of recalcitrant (desiccation-sensitive) seeds of Quercus robur during desiccation. Many of the volatiles were common to both ageing orthodox seeds and desiccating recalcitrant seeds, with alcoholic fermentation forming the major source of volatiles. Finally, comparison was made between two methods of analysis; the first used a Tenax adsorbent to trap volatiles, whilst the second used solid phase microextraction to extract volatiles from the headspace of vials containing powdered seeds. Solid phase microextraction was found to be more sensitive, detecting a far greater number of compounds. Seed volatile analysis provides a non-invasive means of characterizing the processes involved in seed deterioration, and potentially identifying volatile marker compounds for the diagnosis of seed viability loss. PMID:23175670

Effects of pH on the formation of 4(5)-Methylimidazole in glucose/ammonium sulfate and glucose/ammonium sulfite caramel model reactions.

PubMed

Wu, Xinlan; Kong, Fansheng; Huang, Minghui; Yu, Shujuan

2015-10-01

The objective of the present study was to detail the change of 4(5)-Methylimidazole (4-MI) in sulfite and sulfate reactions with different initial pH values. Glucose/ammonium sulfate and glucose/ammonium sulfite reaction systems with initial pH conditions 4.9, 5.9, 6.9, 8.0 and 8.6, were heated at 100°C for 2h, respectively. Higher concentration of methylglyoxal (MGO) and 4-MI was detected in thermal treated glucose/ammonium sulfite reaction system than that in sulfate system. The SO 3 2- reacting with MGO and other precursors of 4-MI at higher pH conditions prevented 4-MI formation. However, no inhibition of 4-MI was found at lower pH conditions due to higher reactivity of the nucleophilic NH 4 + than SO 3 2- . The browning intensity of the sulfite system changed scarcely at higher pH values, which was possibly caused by the polyreaction between SO 3 2- and carbonyl, instead of the intermolecular polymerisation of carbonyl in the advanced stage of the Maillard reaction. Copyright © 2015 Elsevier Ltd. All rights reserved.

Glycation Reactions of Casein Micelles.

PubMed

Moeckel, Ulrike; Duerasch, Anja; Weiz, Alexander; Ruck, Michael; Henle, Thomas

2016-04-13

After suspensions of micellar casein or nonmicellar sodium caseinate had been heated, respectively, in the presence and absence of glucose for 0-4 h at 100 °C, glycation compounds were quantitated. The formation of Amadori products as indicators for the "early" Maillard reaction were in the same range for both micellar and nonmicellar caseins, indicating that reactive amino acid side chains within the micelles are accessible for glucose in a comparable way as in nonmicellar casein. Significant differences, however, were observed concerning the formation of the advanced glycation end products (AGEs), namely, N(ε)-carboxymethyllysine (CML), pyrraline, pentosidine, and glyoxal-lysine dimer (GOLD). CML could be observerd in higher amounts in nonmicellar casein, whereas in the micelles the pyrraline formation was increased. Pentosidine and GOLD were formed in comparable amounts. Furthermore, the extent of protein cross-linking was significantly higher in the glycated casein micelles than in the nonmicellar casein samples. Dynamic light scattering and scanning electron microscopy showed that glycation has no influence on the size of the casein micelles, indicating that cross-linking occurs only in the interior of the micelles, but altered the surface morphology. Studies on glycation and nonenzymatic cross-linking can contribute to the understanding of the structure of casein micelles.

Antioxidant activity and inhibitory effects of 2-hydroxy-3-methylcyclopent-2-enone isolated from ribose-histidine Maillard reaction products on aldose reductase and tyrosinase.

PubMed

Hwang, Seung Hwan; Wang, Zhiqiang; Suh, Hong-Won; Lim, Soon Sung

2018-03-01

This study aimed to better understand the functional properties of ribose and 20 amino acid Maillard reaction products (MRPs). The ABTS + radical scavenging ability of the ribose-20 amino acid MRPs was evaluated. Among the MRPs, ribose-histidine MRPs (RH-MRPs) showed the highest inhibitory activities on the ABTS + radical scavenging ability, aldose reductase (AR), and tyrosinase compared to other MRPs. Functional compounds with antioxidant and AR inhibitory activities have been recognized as an important strategy in the prevention and treatment of diabetic complications, and the search for tyrosinase inhibitors is important for the treatment of hyperpigmentation, development of skin-whitening agents, and use as preservatives in the food industry. On this basis, we sought to isolate and identify compounds with inhibitory activities against AR and tyrosinase. RH-MRPs were heated at 120 °C for 2 h and fractionated using four solvents: methylene chloride (MC), ethyl acetate, n-butanol, and water. The highest inhibitions were found in the MC fraction. The two compounds from this fraction were purified by silica gel column and preparative thin layer chromatography, and identified as 2-hydroxy-3-methylcyclopent-2-enone and furan-3-carboxylic acid. AR inhibition, tyrosinase inhibition, and ABTS + scavenging (IC 50 ) of 2-hydroxy-3-methylcyclopent-2-enone were 4.47, 721.91 and 9.81 μg mL -1 , respectively. In this study, inhibitory effects of 2-hydroxy-3-methylcyclopent-2-enone isolated from RH-MRP were demonstrated on AR, tyrosinase, and its antioxidant activity for the first time. RH-MRP and its constituents can be developed as beneficial functional food sources and cosmetic materials and should be investigated further as potential functional food sources.

Concentrations of pentosidine, an advanced glycation end-product, in umbilical cord blood.

PubMed

Tsukahara, Hirokazu; Ohta, Naoko; Sato, Shuko; Hiraoka, Masahiro; Shukunami, Ken-Ichi; Uchiyama, Mayumi; Kawakami, Hisako; Sekine, Kyouichi; Mayumi, Mitsufumi

2004-07-01

Advanced glycation end-products (AGEs) are formed over several weeks to months by non-enzymatic glycation and oxidation ("glycoxidation") reactions between carbohydrate-derived carbonyl groups and protein amino groups, known as the Maillard reaction. Pentosidine is one of the best-characterized AGEs and is accepted as a satisfactory marker for glycoxidation in vivo. The present study was intended to measure pentosidine concentrations in umbilical cord blood from newborns with various gestational ages using our recently established high-performance liquid chromatography method [Tsukahara, H. et al. (2003) Pediatr. Res. 54, 419-424]. Our study demonstrates, for the first time, that pentosidine is detected in most of the umbilical blood samples. This study also shows that the umbilical blood concentrations of pentosidine are considerably lower than normal adult values, but that they increase with gestation progression and fetal growth. Umbilical pentosidine concentrations were significantly elevated in newborns of mothers with preeclampsia compared to those of mothers without preeclampsia. We conclude that accumulation of AGEs and oxidative stress occurs in fetal tissues and organs in utero at the early stage of human life and that their accumulation is augmented in the maternal preeclampsic condition.

Formation of Fructose-Mediated Advanced Glycation End Products and Their Roles in Metabolic and Inflammatory Diseases.

PubMed

Gugliucci, Alejandro

2017-01-01

Fructose is associated with the biochemical alterations that promote the development of metabolic syndrome (MetS), nonalcoholic fatty liver disease, and type 2 diabetes. Its consumption has increased in parallel with MetS. It is metabolized by the liver, where it stimulates de novo lipogenesis. The triglycerides synthesized lead to hepatic insulin resistance and dyslipidemia. Fructose-derived advanced glycation end products (AGEs) may be involved via the Maillard reaction. Fructose has not been a main focus of glycation research because of the difficulty in measuring its adducts, and, more importantly, because although it is 10 times more reactive than glucose, its plasma concentration is only 1% of that of glucose. In this focused review, I summarize exogenous and endogenous fructose metabolism, fructose glycation, and in vitro, animal, and human data. Fructose is elevated in several tissues of diabetic patients where the polyol pathway is active, reaching the same order of magnitude as glucose. It is plausible that the high reactivity of fructose, directly or via its metabolites, may contribute to the formation of intracellular AGEs and to vascular complications. The evidence, however, is still unconvincing. Two areas that have been overlooked so far and should be actively explored include the following: 1) enteral formation of fructose AGEs, generating an inflammatory response to the receptor for AGEs (which may explain the strong association between fructose consumption and asthma, chronic bronchitis, and arthritis); and 2) inactivation of hepatic AMP-activated protein kinase by a fructose-mediated increase in methylglyoxal flux (perpetuating lipogenesis, fatty liver, and insulin resistance). If proven correct, these mechanisms would put the fructose-mediated Maillard reaction in the limelight again as a contributing factor in chronic inflammatory diseases and MetS. © 2017 American Society for Nutrition.

Formation of Fructose-Mediated Advanced Glycation End Products and Their Roles in Metabolic and Inflammatory Diseases12

PubMed Central

2017-01-01

Fructose is associated with the biochemical alterations that promote the development of metabolic syndrome (MetS), nonalcoholic fatty liver disease, and type 2 diabetes. Its consumption has increased in parallel with MetS. It is metabolized by the liver, where it stimulates de novo lipogenesis. The triglycerides synthesized lead to hepatic insulin resistance and dyslipidemia. Fructose-derived advanced glycation end products (AGEs) may be involved via the Maillard reaction. Fructose has not been a main focus of glycation research because of the difficulty in measuring its adducts, and, more importantly, because although it is 10 times more reactive than glucose, its plasma concentration is only 1% of that of glucose. In this focused review, I summarize exogenous and endogenous fructose metabolism, fructose glycation, and in vitro, animal, and human data. Fructose is elevated in several tissues of diabetic patients where the polyol pathway is active, reaching the same order of magnitude as glucose. It is plausible that the high reactivity of fructose, directly or via its metabolites, may contribute to the formation of intracellular AGEs and to vascular complications. The evidence, however, is still unconvincing. Two areas that have been overlooked so far and should be actively explored include the following: 1) enteral formation of fructose AGEs, generating an inflammatory response to the receptor for AGEs (which may explain the strong association between fructose consumption and asthma, chronic bronchitis, and arthritis); and 2) inactivation of hepatic AMP-activated protein kinase by a fructose-mediated increase in methylglyoxal flux (perpetuating lipogenesis, fatty liver, and insulin resistance). If proven correct, these mechanisms would put the fructose-mediated Maillard reaction in the limelight again as a contributing factor in chronic inflammatory diseases and MetS. PMID:28096127

Proteomic characterization of intermediate and advanced glycation end-products in commercial milk samples.

PubMed

Renzone, Giovanni; Arena, Simona; Scaloni, Andrea

2015-03-18

The Maillard reaction consists of a number of chemical processes affecting the structure of the proteins present in foods. We previously accomplished the proteomic characterization of the lactosylation targets in commercial milk samples. Although characterizing the early modification derivatives, this analysis did not describe the corresponding advanced glycation end-products (AGEs), which may be formed from the further oxidation of former ones or by reaction of oxidized sugars with proteins, when high temperatures are exploited. To fill this gap, we have used combined proteomic procedures for the systematic characterization of the lactosylated and AGE-containing proteins from the soluble and milk fat globule membrane fraction of various milk products. Besides to confirm all lactulosyl-lysines described previously, 40 novel lactosylation sites were identified. More importantly, 308 additional intermediate and advanced glyco-oxidation derivatives (including cross-linking adducts) were characterized in 31 proteins, providing the widest qualitative inventory of modified species ascertained in commercial milk samples so far. Amadori adducts with glucose/galactose, their dehydration products, carboxymethyllysine and glyoxal-, 3-deoxyglucosone/3-deoxygalactosone- and 3-deoxylactosone-derived dihydroxyimidazolines and/or hemiaminals were the most frequent derivatives observed. Depending on thermal treatment, a variable number of modification sites was identified within each protein; their number increased with harder food processing conditions. Among the modified proteins, species involved in assisting the delivery of nutrients, defense response against pathogens and cellular proliferation/differentiation were highly affected by AGE formation. This may lead to a progressive decrease of the milk nutritional value, as it reduces the protein functional properties, abates the bioavailability of the essential amino acids and eventually affects food digestibility. These aspects

Low molecular weight anti-carboxymethyl lysine reactive bands in cashew extracts

USDA-ARS?s Scientific Manuscript database

The Maillard Reaction is the non-enzymatic browning of foods during thermal processing, and is a result of the reaction of reducing sugar carbonyl groups and primary amine groups of proteins. Maillard Reaction products are unstable, and Amadori rearrangements result in a network of chemical modifica...

Advances in copper-catalyzed C-C coupling reactions and related domino reactions based on active methylene compounds.

PubMed

Liu, Yunyun; Wan, Jie-Ping

2012-06-01

Active methylene compounds are a major class of reaction partners for C-C bond formation with sp(2) C-X (X = halide) fragments. As one of the most-classical versions of the Ullmann-type coupling reaction, activated-methylene-based C-C coupling reactions have been efficiently employed in a large number of syntheses. Although this type of reaction has long relied on noble-metal catalysis, the renaissance of copper catalysis at the end of last century has led to dramatic developments in Ullmann C-C coupling reactions. Owing to its low cost, abundance, as well as excellent catalytic activity, the exceptional atom economy of copper catalysis is gaining widespread attention in various organic synthesis. This review summarizes the advances in copper-catalyzed intermolecular and intramolecular C-C coupling reactions that use activated methylene species as well as in tandem reactions that are initiated by this transformation. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Storage stability of cauliflower soup powder: The effect of lipid oxidation and protein degradation reactions.

PubMed

Raitio, Riikka; Orlien, Vibeke; Skibsted, Leif H

2011-09-15

Soups based on cauliflower soup powders, prepared by dry mixing of ingredients and rapeseed oil, showed a decrease in quality, as evaluated by a sensory panel, during the storage of the soup powder in the dark for up to 12weeks under mildly accelerated conditions of 40°C and 75% relative humidity. Antioxidant, shown to be effective in protecting the rapeseed bulk oil, used for the powder preparation, had no effect on storage stability of the soup powder. The freshly prepared soup powder had a relatively high concentration of free radicals, as measured by electron spin resonance spectroscopy, which decreased during storage, and most remarkably during the first two weeks of storage, with only marginal increase in lipid hydroperoxides as primary lipid oxidation products, and without any increase in secondary lipid oxidation products. Analyses of volatiles by SPME-GC-MS revealed a significant increase in concentrations of 2-methyl- and 3-methyl butanals, related to Maillard reactions, together with an increase in 2-acetylpyrrole concentration. The soup powders became more brown during storage, as indicated by a decreasing Hunter L-value, in accord with non-enzymatic browning reactions. A significant increase in the concentrations of dimethyl disulfide in soup powder headspace indicated free radical-initiated protein oxidation. Protein degradation, including Maillard reactions and protein oxidation, is concluded to be more important than lipid oxidation in determining the shelf-life of dry cauliflower soup powder. Copyright © 2011 Elsevier Ltd. All rights reserved.

Maillard Conjugation of Sodium Alginate to Whey Protein for Enhanced Resistance to Surfactant-Induced Competitive Displacement from Air-Water Interfaces.

PubMed

Cai, Bingqing; Saito, Anna; Ikeda, Shinya

2018-01-24

Whey protein adsorbed to an interface forms a viscoelastic interfacial film but is displaced competitively from the interface by a small-molecule surfactant added afterward. The present study evaluated the impact of the covalent conjugation of high- or low-molecular-weight sodium alginate (HA or LA) to whey protein isolate (WPI) via the Maillard reaction on the ability of whey protein to resist surfactant-induced competitive displacement from the air-water interface. Surfactant added after the pre-adsorption of conjugate to the interface increased surface pressure. At a given surface pressure, the WPI-LA conjugate showed a significantly higher interfacial area coverage and lower interfacial film thickness compared to those of the WPI-HA conjugate or unconjugated WPI. The addition of LA to the aqueous phase had little effect on the interfacial area and thickness of pre-adsorbed WPI. These results suggest the importance of the molecular weight of the polysaccharide moiety in determining interfacial properties of whey protein-alginate conjugates.

Chemistry of Amadori rearrangement products: analysis, synthesis, kinetics, reactions, and spectroscopic properties.

PubMed

Yaylayan, V A; Huyghues-Despointes, A

1994-01-01

The chemistry of the key intermediate in the Maillard reaction, the Amadori rearrangements product, is reviewed covering the areas of synthesis, chromatographic analyses, chemical and spectroscopic methods of characterization, reactions, and kinetics. Synthetic strategies involving free and protected sugars are described in detail with specific synthetic procedures. GC- and HPLC-based separations of Amadori products are discussed in relation to the type of columns employed and methods of detection. Applications of infrared (IR) and nuclear magnetic resonance (NMR) spectroscopy for structural elucidation of Amadori products are also reviewed. In addition, mass spectrometry of free, protected, and protein-bound Amadori products under different ionization conditions are presented. The mechanism of acid/base catalyzed thermal degradation reactions of Amadori compounds, as well as their kinetics of formation, are critically evaluated.

Role of amino acids and their Maillard mixtures with ribose in the biosilicification process

NASA Astrophysics Data System (ADS)

Kolb, Vera M.; Liesch, Patrick J.

2006-08-01

Mode of preservation of organic materials on early Earth, Mars or other extraterrestrial objects, and during the space transport on objects such as meteors, is one of the NASA's interests. This is especially true for the bio-organic materials, which could indicate life, past or present. Finding of such materials preserved in some ancient rocks, for example, could be interpreted as a biosignature. We have developed an experimental model for silicification, in which we have synthesized silica gels by reacting sodium silicate solution with various amino acids and with their mixtures with sugars, so-called Maillard mixtures. Our results indicate that these organic materials cause rapid and massive polymerization of silica. Such process may encrust organics or small organisms and thus preserve them. We have studied the gels we synthesized by the infrared (IR) spectroscopic method, and have detected small amount of the organic material in the silica gel. The gels were distinct in each case and have aged differently. In some cases, gel-sol-gel transformations were observed, which may be important for transport of both gels and the organics under prebiotic conditions. The gels obtained from the Maillard mixtures differ from those from the amino acids. Deuteration of the gels was performed in an attempt to resolve the bands in the Si-O-Si and Si-O-C region.

Advancing the sensitivity of selected reaction monitoring-based targeted quantitative proteomics

PubMed Central

Shi, Tujin; Su, Dian; Liu, Tao; Tang, Keqi; Camp, David G.; Qian, Wei-Jun; Smith, Richard D.

2012-01-01

Selected reaction monitoring (SRM)—also known as multiple reaction monitoring (MRM)—has emerged as a promising high-throughput targeted protein quantification technology for candidate biomarker verification and systems biology applications. A major bottleneck for current SRM technology, however, is insufficient sensitivity for e.g., detecting low-abundance biomarkers likely present at the low ng/mL to pg/mL range in human blood plasma or serum, or extremely low-abundance signaling proteins in cells or tissues. Herein we review recent advances in methods and technologies, including front-end immunoaffinity depletion, fractionation, selective enrichment of target proteins/peptides including posttranslational modifications (PTMs), as well as advances in MS instrumentation which have significantly enhanced the overall sensitivity of SRM assays and enabled the detection of low-abundance proteins at low to sub- ng/mL level in human blood plasma or serum. General perspectives on the potential of achieving sufficient sensitivity for detection of pg/mL level proteins in plasma are also discussed. PMID:22577010

[Advanced glycation end products: A risk factor for human health].

PubMed

Wautier, M-P; Tessier, F J; Wautier, J-L

2014-11-01

Advanced glycation end products (AGE) result from a chemical reaction between the carbonyl group of reducing sugar and the nucleophilic NH2 of a free amino acid or a protein; lysine and arginine being the main reactive amino acids on proteins. Following this first step, a molecular rearrangement occurs, rearrangement of Amadori resulting to the formation of Maillard products. Glycation can cause the clouding of the lens by inducing reactions crosslinking proteins. Specialized receptors (RAGE, Galectin 3…) bind AGE. The binding to the receptor causes the formation of free radicals, which have a deleterious effect because they are powerful oxidizing agents, but also play the role of intracellular messenger, altering the cell functions. This is especially true at the level of endothelial cells: the attachment of AGE to RAGE receptor causes an increase in vascular permeability. AGE binding to endothelium RAGE and to monocytes-macrophages, led to the production of cytokines, growth factors, to the expression of adhesion molecules, and the production of procoagulant activity. Diabetic retinopathy is related to excessive secretion of vascular growth factor (vascular endothelial growth factor [VEGF]). AGE-RAGE receptor binding causes the synthesis and secretion of VEGF. Increased permeability, facilitation of leukocyte migration, the production of reactive oxygen species, cytokines and VEGF suggest that the AGE could be an element of a cascade of reactions responsible for the diabetic angiopathy and vascular damages observed during aging and chronic renal failure. Balanced diet or some drugs can limit the deleterious effect of AGE. Copyright © 2014 Elsevier Masson SAS. All rights reserved.

Heat damage and in vitro starch digestibility of puffed wheat kernels.

PubMed

Cattaneo, Stefano; Hidalgo, Alyssa; Masotti, Fabio; Stuknytė, Milda; Brandolini, Andrea; De Noni, Ivano

2015-12-01

The effect of processing conditions on heat damage, starch digestibility, release of advanced glycation end products (AGEs) and antioxidant capacity of puffed cereals was studied. The determination of several markers arising from Maillard reaction proved pyrraline (PYR) and hydroxymethylfurfural (HMF) as the most reliable indices of heat load applied during puffing. The considerable heat load was evidenced by the high levels of both PYR (57.6-153.4 mg kg(-1) dry matter) and HMF (13-51.2 mg kg(-1) dry matter). For cost and simplicity, HMF looked like the most appropriate index in puffed cereals. Puffing influenced starch in vitro digestibility, being most of the starch (81-93%) hydrolyzed to maltotriose, maltose and glucose whereas only limited amounts of AGEs were released. The relevant antioxidant capacity revealed by digested puffed kernels can be ascribed to both the new formed Maillard reaction products and the conditions adopted during in vitro digestion. Copyright © 2015 Elsevier Ltd. All rights reserved.

Changes in chemical composition and antioxidative properties of rye ginger cakes during their shelf-life.

PubMed

Zieliński, Henryk; del Castillo, Maria Dolores; Przygodzka, Małgorzata; Ciesarova, Zuzana; Kukurova, Kristina; Zielińska, Danuta

2012-12-15

Changes in chemical composition and antioxidative properties of rye ginger cakes during their shelf-life were investigated in this study. In particular, the changes in antioxidants content, antioxidative and reducing capacity, and Maillard reaction development in rye ginger cakes after long-term storage were addressed. Ginger cakes produced according to the traditional and current recipe were stored for 5 years at room temperature in a dark place. The total phenolic compounds (TPC), inositol hexaphosphate (IP6), reduced (GSH) and oxidised glutathione (GSSG) contents, antioxidant and reducing capacity and Maillard reaction products (MRPs) were determined in ginger cakes after storage and then compared to those measured after baking. After long-term storage a decrease in TPC and IP6 contents in cakes was noted. In contrast, an increase in antioxidative and reducing capacity of stored cakes was observed. Long-term storage induced formation of furosine, advanced and final Maillard reaction products and caused changes in both reduced and oxidised forms of glutathione. After long-term storage the modest changes in furosine, FAST index and browning in ginger cake formulated with dark rye flour may suggest that this product is the healthiest among others. Therefore, traditional rye ginger cakes can be considered as an example of a healthy food that is also relatively stable during long term storage as noted by the small chemical changes observed in its composition. Copyright © 2012 Elsevier Ltd. All rights reserved.

Immunohistochemical detection of advanced glycosylation end products in diabetic tissues using monoclonal antibody to pyrraline.

PubMed Central

Miyata, S; Monnier, V

1992-01-01

Pyrraline is one of the major Maillard compounds resulting from the reaction of glucose with amino compounds at slightly acidic pH. For in vivo studies, monoclonal pyrraline antibodies were raised after immunization of Balb/c mice with keyhole limpet hemocyamin-caproyl pyrraline conjugate. Of 660 hybridoma clones from one donor, 260 produced an antibody to the free hapten, two of which named Pyr-A and Pyr-B also cross-reacted with L-lysyl pyrraline. Using Pyr-B antibody and an ELISA, a gradual increase in pyrraline immunoreactivity was observed in serum albumin incubated with glucose or 3-deoxyglucosone. Plasma pyrraline levels increased fourfold (P less than 0.001) in Sprague-Dawley rats upon induction of diabetes with streptozotocin and were twofold increased in randomly selected plasmas from diabetic humans. Highly specific pyrraline immunoreactivity was detected in sclerosed glomeruli from diabetic and old normal kidneys as well as in renal arteries with arteriolosclerosis and in perivascular and peritubular sclerosed extracellular matrix and basement membranes. The preferential localization of pyrraline immunoreactivity in the extracellular matrix strengthens the notion that the advanced glycosylation reaction may contribute to decreased turnover and thickening of the extracellular matrix in diabetes and aging. Images PMID:1556177

Advancing the sensitivity of selected reaction monitoring-based targeted quantitative proteomics

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shi, Tujin; Su, Dian; Liu, Tao

2012-04-01

Selected reaction monitoring (SRM)—also known as multiple reaction monitoring (MRM)—has emerged as a promising high-throughput targeted protein quantification technology for candidate biomarker verification and systems biology applications. A major bottleneck for current SRM technology, however, is insufficient sensitivity for e.g., detecting low-abundance biomarkers likely present at the pg/mL to low ng/mL range in human blood plasma or serum, or extremely low-abundance signaling proteins in the cells or tissues. Herein we review recent advances in methods and technologies, including front-end immunoaffinity depletion, fractionation, selective enrichment of target proteins/peptides or their posttranslational modifications (PTMs), as well as advances in MS instrumentation, whichmore » have significantly enhanced the overall sensitivity of SRM assays and enabled the detection of low-abundance proteins at low to sub- ng/mL level in human blood plasma or serum. General perspectives on the potential of achieving sufficient sensitivity for detection of pg/mL level proteins in plasma are also discussed.« less

Relative quantification of N(epsilon)-(Carboxymethyl)lysine, imidazolone A, and the Amadori product in glycated lysozyme by MALDI-TOF mass spectrometry.

PubMed

Kislinger, Thomas; Humeny, Andreas; Peich, Carlo C; Zhang, Xiaohong; Niwa, Toshimitsu; Pischetsrieder, Monika; Becker, Cord-Michael

2003-01-01

The nonenzymatic glycation of proteins by reducing sugars, also known as the Maillard reaction, has received increasing recognition from nutritional science and medical research. In this study, we applied matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF-MS) to perform relative and simultaneous quantification of the Amadori product, which is an early glycation product, and of N(epsilon)-(carboxymethyl)lysine and imidazolone A, two important advanced glycation end products. Therefore, native lysozyme was incubated with d-glucose for increasing periods of time (1, 4, 8, and 16 weeks) in phosphate-buffered saline pH 7.8 at 50 degrees C. After enzymatic digestion with endoproteinase Glu-C, the N-terminal peptide fragment (m/z 838; amino acid sequence KVFGRCE) and the C-terminal peptide fragment (m/z 1202; amino acid sequence VQAWIRGCRL) were used for relative quantification of the three Maillard products. Amadori product, N(epsilon)-(carboxymethyl)lysine, and imidazolone A were the main glycation products formed under these conditions. Their formation was dependent on glucose concentration and reaction time. The kinetics were similar to those obtained by competitive ELISA, an established method for quantification of N(epsilon)-(carboxymethyl)lysine and imidazolone A. Inhibition experiments showed that coincubation with N(alpha)-acetylargine suppressed formation of imidazolone A but not of the Amadori product or N(epsilon)-(carboxymethyl)lysine. The presence of N(alpha)-acetyllysine resulted in the inhibition of lysine modifications but in higher concentrations of imidazolone A. o-Phenylenediamine decreased the yield of the Amadori product and completely inhibited the formation of N(epsilon)-(carboxymethyl)lysine and imidazolone A. MALDI-TOF-MS proved to be a new analytical tool for the simultaneous, relative quantification of specific products of the Maillard reaction. For the first time, kinetic data of defined products on

Recent advances in the understanding of severe cutaneous adverse reactions.

PubMed

Adler, N R; Aung, A K; Ergen, E N; Trubiano, J; Goh, M S Y; Phillips, E J

2017-11-01

Severe cutaneous adverse reactions (SCARs) encompass a heterogeneous group of delayed hypersensitivity reactions, which are most frequently caused by drugs. Our understanding of several aspects of SCAR syndromes has evolved considerably over the last decade. This review explores evolving knowledge of the immunopathogenic mechanisms, pharmacogenomic associations, in vivo and ex vivo diagnostics for causality assessment, and medication cross-reactivity data related to SCAR syndromes. Given the rarity and severity of these diseases, multidisciplinary collaboration through large international, national and/or multicentre networks to collect prospective data on patients with SCAR syndromes should be prioritized. This will further enhance a systematized framework for translating epidemiological, clinical and immunopathogenetic advances into preventive efforts and improved outcomes for patients. © 2017 British Association of Dermatologists.

Okara promoted acrylamide and carboxymethyl-lysine formation in bakery products.

PubMed

Palermo, Mariantonella; Fiore, Alberto; Fogliano, Vincenzo

2012-10-10

Soybeans are widely used in bakery products because of their technological advantages and, recently, soybean-containing products have been marketed as functional foods thanks to several health benefits. Okara is a soybean-based ingredient obtained after elimination of the water-soluble component from ground soybeans. In this paper the effect of okara addition to bakery products on the formation of some potentially harmful Maillard reaction products was evaluated. Cookies obtained by replacing 15% of wheat flour with okara showed a visible browning increase and a more intense Maillard reaction development as shown by higher concentrations of 5-hydroxymethyl-2-furaldehyde (HMF) (+100%), acrylamide (+60%), and carboxymethyl-lysine (CML) (+400%) with respect to the control. This phenomenon could be related to the presence in okara of about 50% of insoluble dietary fiber: the fiber reduces water activity during cooking, thus promoting Maillard reaction. To confirm this hypothesis, cookies obtained by replacing 7% of wheat flour with three different types of dietary fiber (cellulose, chitosan, and pea fiber) were prepared: these experimental cookies showed higher Maillard reaction product concentration with respect to the control and, in particular, HMF and CML values were directly related to the fiber water-holding capacity (WHC). To extend the observation to the food market, a sampling of soybean-containing commercial bakery products was analyzed by comparing the concentrations of Maillard reaction products with those of similar bakery products without soy. Soybean-containing samples showed higher concentrations of acrylamide and CML than corresponding controls.

Digestibility of Glyoxal-Glycated β-Casein and β-Lactoglobulin and Distribution of Peptide-Bound Advanced Glycation End Products in Gastrointestinal Digests.

PubMed

Zhao, Di; Li, Lin; Le, Thao T; Larsen, Lotte Bach; Su, Guoying; Liang, Yi; Li, Bing

2017-07-19

This work reports the influence of glyoxal (GO)-derived glycation on the gastrointestinal enzymatic hydrolysis of β-lactoglobulin and β-casein. Reduced digestibility of glycated proteins was found in both gastric and intestinal stage. Distribution of Maillard reaction products in digests with different molecular weight ranges was investigated subsequently. The colorless and brown MRPs largely presented in the digests smaller than 20 kDa. However, the resistance of fluorescent advanced glycation end products (AGEs) to enzymatic hydrolysis gradually increased during glycation, rendering fluorescent AGEs largely present in the digests larger than 20 kDa. No free N (ε)-carboxymethyllysine (CML) was detected in digests. The relative amount of CML in digests larger than 1 kDa was higher than that of Lys, demonstrating the hindrance of CML to enzymatic hydrolysis. This study highlights the resistance of GO-derived AGEs to digestive proteases via blockage of tryptic cleavage sites or steric hindrance, which is a barrier to the absorption of dietary AGEs.

Phenolic acids inhibit the formation of advanced glycation end products in food simulation systems depending on their reducing powers and structures.

PubMed

Chen, Hengye; Virk, Muhammad Safiullah; Chen, Fusheng

2016-06-01

The concentration of advanced glycation end products (AGEs) in foods, which are formed by Maillard reaction, has demonstrated as risk factors associated with many chronic diseases. The AGEs inhibitory activities of five common phenolic acids (protocatechuic acid, dihydroferulic acid, p-coumaric acid, p-hydroxybenzoic acid and salicylic acid) with different chemical properties had been investigated in two food simulation systems (glucose-bovine serum albumin (BSA) and oleic acid-BSA). The results substantiated that the AGEs inhibitory abilities of phenolic acids in the oleic acid BSA system were much better than the glucose-BSA system for their strong reducing powers and structures. Among them, dihydrogenferulic acid showed strong inhibition of AGEs formation in oleic acid-BSA system at 0.01 mg/mL compared to nonsignificant AGEs inhibitory effect in oleic acid-BSA system at 10-fold higher concentration (0.1 mg/mL). This study suggests that edible plants rich in phenolic acids may be used as AGEs inhibitor during high-fat cooking.

Modeling Interfacial Glass-Water Reactions: Recent Advances and Current Limitations

DOE PAGES

Pierce, Eric M.; Frugier, Pierre; Criscenti, Louise J.; ...

2014-07-12

Describing the reactions that occur at the glass-water interface and control the development of the altered layer constitutes one of the main scientific challenges impeding existing models from providing accurate radionuclide release estimates. Radionuclide release estimates are a critical component of the safety basis for geologic repositories. The altered layer (i.e., amorphous hydrated surface layer and crystalline reaction products) represents a complex region, both physically and chemically, sandwiched between two distinct boundaries pristine glass surface at the inner most interface and aqueous solution at the outer most interface. Computational models, spanning different length and time-scales, are currently being developed tomore » improve our understanding of this complex and dynamic process with the goal of accurately describing the pore-scale changes that occur as the system evolves. These modeling approaches include geochemical simulations [i.e., classical reaction path simulations and glass reactivity in allowance for alteration layer (GRAAL) simulations], Monte Carlo simulations, and Molecular Dynamics methods. Finally, in this manuscript, we discuss the advances and limitations of each modeling approach placed in the context of the glass-water reaction and how collectively these approaches provide insights into the mechanisms that control the formation and evolution of altered layers.« less

Assessment of heat treatment of dairy products by MALDI-TOF-MS.

PubMed

Meltretter, Jasmin; Birlouez-Aragon, Inès; Becker, Cord-Michael; Pischetsrieder, Monika

2009-12-01

The formation of the Amadori product from lactose (protein lactosylation) is a major parameter to evaluate the quality of processed milk. Here, MALDI-TOF-MS was used for the relative quantification of lactose-adducts in heated milk. Milk was heated at a temperature of 70, 80, and 100 degrees C between 0 and 300 min, diluted, and subjected directly to MALDI-TOF-MS. The lactosylation rate of alpha-lactalbumin increased with increasing reaction temperature and time. The results correlated well with established markers for heat treatment of milk (concentration of total soluble protein, soluble alpha-lactalbumin and beta-lactoglobulin at pH 4.6, and fluorescence of advanced Maillard products and soluble tryptophan index; r=0.969-0.997). The method was also applied to examine commercially available dairy products. In severely heated products, protein pre-purification by immobilized metal affinity chromatography improved spectra quality. Relative quantification of protein lactosylation by MALDI-TOF-MS proved to be a very fast and reliable method to monitor early Maillard reaction during milk processing.

Theoretical insight into reaction mechanisms of 2,4-dinitroanisole with hydroxyl radicals for advanced oxidation processes.

PubMed

Zhou, Yang; Liu, Xiaoqiang; Jiang, Weidong; Shu, Yuanjie

2018-01-24

The detailed degradation mechanism of an insensitive explosive, 2,4-dinitroanisole (DNAN), in advanced oxidation processes (AOPs) was investigated computationally at the M06-2X/6-311 + G(d,p)/SMD level of theory. Results obtained show that the addition-elimination reaction is the dominant mechanism. The phenol products formed can continue to be oxidized to benzoquinone radicals that are often detected by experiments and may be the initial reactants of ring-opening reactions. The H-abstraction reaction is an unavoidable competing mechanism; the intermediate generated can also undergo the process of addition-elimination reaction. The nitro departure reaction involves not only hydroxyl radical (•OH), but also other active substances (such as •H). More importantly, we found that AOP technology can easily degrade DNAN, similar to TNT and DNT. Thus, this method is worth trying in experiments. The conclusions of this work provide theoretical support for such experimental research. Graphical abstract Possible pathways of degradation by •OH radicals in advanced oxidation processes (AOPs) of the typical insensitive explosive 2,4-dinitroanisole (DNAN) were investigated by density functional theory (DFT) methods. Based on the Gibbs free energy barriers and intermediates, the dominant reaction mechanism was determined. The conclusions will be helpful in utilizing AOP technology to remove DNAN pollution.

Lysine-Derived Protein-Bound Heyns Compounds in Bakery Products.

PubMed

Treibmann, Stephanie; Hellwig, Anne; Hellwig, Michael; Henle, Thomas

2017-12-06

Fructose and dicarbonyl compounds resulting from fructose in heated foods have been linked to pathophysiological pathways of several metabolic disorders. Up to now, very little has been known about the Maillard reaction of fructose in food. Heyns rearrangement compounds (HRCs), the first stable intermediates of the Maillard reaction between amino components and fructose, have not yet been quantitated as protein-bound products in food. Therefore, the HRCs glucosyllysine and mannosyllysine were synthesized and characterized by NMR. Protein-bound HRCs in cookies containing various sugars and in commercial bakery products were quantitated after enzymatic hydrolysis by RP-HPLC-ESI-MS/MS in the multiple reaction monitoring mode through application of the standard addition method. Protein-bound HRCs were quantitated for the first time in model cookies and in commercial bakery products containing honey, banana, and invert sugar syrup. Concentrations of HRCs from 19 to 287 mg/kg were found, which were similar to or exceeded the content of other frequently analyzed Maillard reaction products, such as N-ε-carboxymethyllysine (10-76 mg/kg), N-ε-carboxyethyllysine (2.5-53 mg/kg), and methylglyoxal-derived hydroimidazolone 1 (10-218 mg/kg) in the analyzed cookies. These results show that substantial amounts of HRCs form during food processing. Analysis of protein-bound HRCs in cookies is therefore useful to evaluate the Maillard reaction of fructose.

Advanced Precursor Reaction Processing for Cu(InGa)(SeS)2 Solar Cells

DOE Office of Scientific and Technical Information (OSTI.GOV)

Shafarman, William N.

This project “Advanced Precursor Reaction Processing for Cu(InGa)(SeS)2 Solar Cells”, completed by the Institute of Energy Conversion (IEC) at the University of Delaware in collaboration with the Department of Chemical Engineering at the University of Florida, developed the fundamental understanding and technology to increase module efficiency and improve the manufacturability of Cu(InGa)(SeS)2 films using the precursor reaction approach currently being developed by a number of companies. Key results included: (1) development of a three-step H2Se/Ar/H2S reaction process to control Ga distribution through the film and minimizes back contact MoSe2 formation; (2) Ag-alloying to improve precursor homogeneity by avoiding In phasemore » agglomeration, faster reaction and improved adhesion to allow wider reaction process window; (3) addition of Sb, Bi, and Te interlayers at the Mo/precursor junction to produce more uniform precursor morphology and improve adhesion with reduced void formation in reacted films; (4) a precursor structure containing Se and a reaction process to reduce processing time to 5 minutes and eliminate H2Se usage, thereby increasing throughput and reducing costs. All these results were supported by detailed characterization of the film growth, reaction pathways, thermodynamic assessment and device behavior.« less

The use of asparaginase to reduce acrylamide levels in cooked food.

PubMed

Xu, Fei; Oruna-Concha, Maria-Jose; Elmore, J Stephen

2016-11-01

Strategies proposed for reducing the formation of the suspected carcinogen acrylamide in cooked foods often rely on a reduction in the extent of the Maillard reaction, in which acrylamide is formed from the reaction between asparagine and reducing sugars. However, the Maillard reaction also provides desirable sensory attributes of cooked foods. Mitigation procedures that modify the Maillard reaction may negatively affect flavour and colour. The use of asparaginase to convert asparagine to aspartic acid may provide a means to reduce acrylamide formation, while maintaining sensory quality. This review collates research on the use of enzymes, asparaginase in particular, to mitigate acrylamide formation. Asparaginase is a powerful tool for the food industry and it is likely that its use will increase. However, the potential adverse effects of asparaginase treatment on sensory properties of cooked foods and the need to achieve sufficient enzyme-substrate contact remain areas for future research. Copyright © 2016 Elsevier Ltd. All rights reserved.

Workshop on Critical Issues in Microgravity Fluids, Transport, and Reaction Processes in Advanced Human Support Technology

NASA Technical Reports Server (NTRS)

Chiaramonte, Francis P.; Joshi, Jitendra A.

2004-01-01

This workshop was designed to bring the experts from the Advanced Human Support Technologies communities together to identify the most pressing and fruitful areas of research where success hinges on collaborative research between the two communities. Thus an effort was made to bring together experts in both advanced human support technologies and microgravity fluids, transport and reaction processes. Expertise was drawn from academia, national laboratories, and the federal government. The intent was to bring about a thorough exchange of ideas and develop recommendations to address the significant open design and operation issues for human support systems that are affected by fluid physics, transport and reaction processes. This report provides a summary of key discussions, findings, and recommendations.

Amino Acids Inhibitory Effects and Mechanism on 2-Amino-1-Methyl-6-Phenylimidazo [4,5-b]Pyridine (PhIP) Formation in the Maillard Reaction Model Systems.

PubMed

Linghu, Ziyi; Karim, Faris; Smith, J Scott

2017-12-01

This study was to investigate the inhibitory effects of amino acids (AAs) on the formation of 2-amino-1-methyl-6-phenylimidazo [4,5-b]pyridine (PhIP) and to evaluate the inhibition mechanism of PhIP in Maillard model systems. Different AAs were individually added into model systems heat-treated at 180 °C/1 h. The PhIP, phenylacetaldehyde (PheAce), and pyrazines derivatives were determined using HPLC and GC-MS. AAs significantly reduced (P < 0.05) PhIP levels in a dose-dependent response, ranking as: Trp = Lys > Pro > Leu > Met > Val > Ile > Thr > Phe > Asp, at the highest molar ratio. The PheAce content was gradually reduced with increasing AAs levels, suggesting that AAs may inhibit PhIP formation through scavenging the available PheAce. A correlation between PhIP inhibition and PheAce-scavenging activity of AAs was observed when PheAce and AAs were heated. The variety and quantity of pyrazines formed are highly depending on the type of AAs. © 2017 Institute of Food Technologists®.

Probing Conformational Change of Bovine Serum Albumin–Dextran Conjugates under Controlled Dry Heating

DOE Office of Scientific and Technical Information (OSTI.GOV)

Xia, Shuqin; Li, Yunqi; Zhao, Qin

2015-04-29

The time-dependent conformational change of bovine serum album (BSA) during Maillard reaction with dextran under controlled dry heating has been studied by small-angle X-ray scattering, fluorescence spectroscopy, dynamic light scattering, and circular dichroism analysis. Through the research on the radii of gyration (R g), intrinsic fluorescence, and secondary structure, conjugates with dextran coating were found to inhibit BSA aggregation and preserve the secondary structure of native BSA against long-time heat treatment during Maillard reaction. The results suggested that the hydrophilic dextran was conjugated to the compact protein surface and enclosed it and more dextran chains were attached to BSA withmore » the increase of the heating time. The study presented here will be beneficial to the understanding of the conformational evolution of BSA molecules during the dry-heating Maillard reaction and to the control of the protein–polysaccharide conjugate structure.« less

Advances in quantum and molecular mechanical (QM/MM) simulations for organic and enzymatic reactions.

PubMed

Acevedo, Orlando; Jorgensen, William L

2010-01-19

Application of combined quantum and molecular mechanical (QM/MM) methods focuses on predicting activation barriers and the structures of stationary points for organic and enzymatic reactions. Characterization of the factors that stabilize transition structures in solution and in enzyme active sites provides a basis for design and optimization of catalysts. Continued technological advances allowed for expansion from prototypical cases to mechanistic studies featuring detailed enzyme and condensed-phase environments with full integration of the QM calculations and configurational sampling. This required improved algorithms featuring fast QM methods, advances in computing changes in free energies including free-energy perturbation (FEP) calculations, and enhanced configurational sampling. In particular, the present Account highlights development of the PDDG/PM3 semi-empirical QM method, computation of multi-dimensional potentials of mean force (PMF), incorporation of on-the-fly QM in Monte Carlo (MC) simulations, and a polynomial quadrature method for efficient modeling of proton-transfer reactions. The utility of this QM/MM/MC/FEP methodology is illustrated for a variety of organic reactions including substitution, decarboxylation, elimination, and pericyclic reactions. A comparison to experimental kinetic results on medium effects has verified the accuracy of the QM/MM approach in the full range of solvents from hydrocarbons to water to ionic liquids. Corresponding results from ab initio and density functional theory (DFT) methods with continuum-based treatments of solvation reveal deficiencies, particularly for protic solvents. Also summarized in this Account are three specific QM/MM applications to biomolecular systems: (1) a recent study that clarified the mechanism for the reaction of 2-pyrone derivatives catalyzed by macrophomate synthase as a tandem Michael-aldol sequence rather than a Diels-Alder reaction, (2) elucidation of the mechanism of action of fatty

Fish in Vitro Digestion: Influence of Fish Salting on the Extent of Lipolysis, Oxidation, and Other Reactions.

PubMed

Nieva-Echevarría, Bárbara; Goicoechea, Encarnación; Manzanos, María J; Guillén, María D

2017-02-01

A study of the various chemical reactions which take place during fish in vitro digestion and the potential effect of fish salting on their extent is addressed for the first time. Farmed European sea bass fillets, raw, brine-salted or dry-salted, were digested using a gastrointestinal in vitro model. Fish lipid extracts before and after digestion were analyzed by 1 H NMR, and the headspace composition of the digestates was investigated by SPME-GC/MS. During digestion, not only lipolysis, but also fish lipid oxidation took place. This latter was evidenced by the generation of conjugated dienes supported on chains having also hydroperoxy- and hydroxy-groups (primary oxidation compounds), by the increase of volatile secondary oxidation products, and by the decrease of the antioxidant 2,6-di-tert-butyl-hydroxytoluene (BHT). Likewise, esterification and Maillard-type reactions also occurred. Salting, and especially dry-salting, enhanced all these reactions, except for lipolysis, during digestion.

Advancing the Theory of Nuclear Reactions with Rare Isotopes: From the Laboratory to the Cosmos

DOE Office of Scientific and Technical Information (OSTI.GOV)

Elster, Charlotte

2015-06-01

The mission of the TORUS Topical Collaboration is to develop new methods that will advance nuclear reaction theory for unstable isotopes by using three-body techniques to improve direct-reaction calculations, and, by using a new partial-fusion theory, to integrate descriptions of direct and compound-nucleus reactions. Ohio University concentrates its efforts on the first part of the mission. Since direct measurements are often not feasible, indirect methods, e.g. (d,p) reactions, should be used. Those (d,p) reactions may be viewed as three-body reactions and described with Faddeev techniques. Faddeev equations in momentum space have a long tradition of utilizing separable interactions in ordermore » to arrive at sets of coupled integral equations in one variable. While there exist several separable representations for the nucleon-nucleon interaction, the optical potential between a neutron (proton) and a nucleus is not readily available in separable form. For this reason we first embarked in introducing a separable representation for complex phenomenological optical potentials of Woods-Saxon type.« less

An analysis of the changes on intermediate products during the thermal processing of black garlic.

PubMed

Yuan, Heng; Sun, Linjuan; Chen, Min; Wang, Jun

2018-01-15

The thermal processing of black garlic was simulated. Fresh garlic was incubated at 55°C with 80% humidity and sampled every 5 or 10days. The changes in relevant products were as follows: the fructan content was decreased by 84.79%, and the fructose content was increased by 508.11%. The contents of Maillard reaction intermediate products were first increased and then decreased. The colour of garlic gradually became dark and the pH decreased from 6.13 to 4.00. By analyzing these changes, the mechanism of black garlic formation and the changes on the Maillard reaction were revealed. The sweetness of black garlic resulted mainly from the fructose that was produced, and the black colour was largely due to the Maillard reaction between fructose/glucose and amino acids. An understanding of this process is useful to explain the formation mechanism of black garlic and could lead to better control of the quality of black garlic. Copyright © 2017 Elsevier Ltd. All rights reserved.

Advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects.

PubMed

Sicherer, Scott H; Leung, Donald Y M

2006-07-01

This review highlights some of the research advances in anaphylaxis; hypersensitivity reactions to foods, drugs, and insects; and allergic skin disease that were reported primarily in the Journal in 2005. Although studies documented deficiencies in community management of anaphylaxis, guidelines and National Institutes of Health summary reports provide direction toward improved research and education. At least 9% of young children "outgrow" a tree nut allergy. Advances in food allergy diagnosis include reports of probability of reactions to peanut at various peanut-specific IgE concentrations and skin test response size and the utility of evaluating IgE binding to specific epitopes. Future food allergy treatments might include selection of "less allergenic" fruit cultivars, genetic silencing of major allergens, and treatment of allergic patients with Chinese herbal remedies. Osteopontin might be a useful biomarker for success of venom immunotherapy. Progress in our understanding of the immunology of atopic dermatitis and autoimmune urticaria has also been made. These observations will likely contribute toward optimizing management of these common allergic disorders.

Recent advances in the design of tailored nanomaterials for efficient oxygen reduction reaction

DOE PAGES

Lv, Haifeng; Li, Dongguo; Strmcnik, Dusan; ...

2016-04-11

In the past decade, polymer electrolyte membrane fuels (PEMFCs) have been evaluated for both automotive and stationary applications. One of the main obstacles for large scale commercialization of this technology is related to the sluggish oxygen reduction reaction that takes place on the cathode side of fuel cell. Consequently, ongoing research efforts are focused on the design of cathode materials that could improve the kinetics and durability. Majority of these efforts rely on novel synthetic approaches that provide control over the structure, size, shape and composition of catalytically active materials. This article highlights the most recent advances that have beenmore » made to tailor critical parameters of the nanoscale materials in order to achieve more efficient performance of the oxygen reduction reaction (ORR).« less

Advancing the Theory of Nuclear Reactions with Rare Isotopes. From the Laboratory to the Cosmos

DOE Office of Scientific and Technical Information (OSTI.GOV)

Nunes, Filomena

2015-06-01

The mission of the Topical Collaboration on the Theory of Reactions for Unstable iSotopes (TORUS) was to develop new methods to advance nuclear reaction theory for unstable isotopes—particularly the (d,p) reaction in which a deuteron, composed of a proton and a neutron, transfers its neutron to an unstable nucleus. After benchmarking the state-of-the-art theories, the TORUS collaboration found that there were no exact methods to study (d,p) reactions involving heavy targets; the difficulty arising from the long-range nature of the well known, yet subtle, Coulomb force. To overcome this challenge, the TORUS collaboration developed a new theory where the complexitymore » of treating the long-range Coulomb interaction is shifted to the calculation of so-called form-factors. An efficient implementation for the computation of these form factors was a major achievement of the TORUS collaboration. All the new machinery developed are essential ingredients to analyse (d,p) reactions involving heavy nuclei relevant for astrophysics, energy production, and stockpile stewardship.« less

Advances in heterocycle synthesis via [3+m]-cycloaddition reactions involving an azaoxyallyl cation as the key intermediate.

PubMed

Xuan, Jun; Cao, Xia; Cheng, Xiao

2018-05-17

Heterocyclic compounds are widely found in many natural isolates and medicinally relevant compounds, as well as some fine chemicals. The development of general and efficient methods for the construction of heterocyclic compounds is one of the most important tasks in synthetic organic chemistry. Along these lines, [3+m]-cycloaddition reactions involving in situ generated azaoxyallyl cations as the 3-atom units have emerged as a powerful method for the synthesis of nitrogen-containing heterocycles. In this feature article, we highlight recent advances in this rapidly growing area, mainly focusing on the reaction design as well as the reaction mechanism.

Quantifying atom addition reactions on amorphous solid water: a review of recent laboratory advances

NASA Astrophysics Data System (ADS)

He, Jiao; Vidali, Gianfranco

2018-06-01

Complex organic molecules found in space are mostly formed on and in the ice mantle covering interstellar dust grains. In clouds where ionizing irradiation is insignificant, chemical reactions on the ice mantle are dominated by thermal processes. Modeling of grain surface chemistry requires detailed information from the laboratory, including sticking coefficients, binding energies, diffusion energy barriers, mechanism of reaction, and chemical desorption rates. In this talk, recent laboratory advances in obtaining these information would be reviewed. Specifically, this talk will focus on the efforts in our group in: 1) Determining the mechanism of atomic hydrogen addition reactions on amorphous solid water (ASW); 2) Measuring the chemical desorption coefficient of H+O3-->O2+OH using the time-resolved scattering technique; and 3) Measuring the diffusion energy barrier of volatile molecules on ASW. Further laboratory studies will be suggested.This research was supported by NSF Astronomy & Astrophysics Research Grant #1615897.

1H NMR and SPME-GC/MS study of hydrolysis, oxidation and other reactions occurring during in vitro digestion of non-oxidized and oxidized sunflower oil. Formation of hydroxy-octadecadienoates.

PubMed

Nieva-Echevarría, Bárbara; Goicoechea, Encarnación; Manzanos, María J; Guillén, María D

2017-01-01

Both fresh and slightly oxidized sunflower oils, as models of omega-6 rich lipids, were submitted to in vitro gastrointestinal digestion and studied by 1 H NMR and SPME-GC/MS. Changes in lipolysis degree, lipid composition and oxidative level were studied by 1 H NMR. Three quantitative approaches were used and several equations were newly developed. In oxidized oil digestates slightly lower hydrolysis and a higher advance of oxidation took place during digestion. This latter was evidenced by a greater decrease of lipid unsaturation degree and enhanced generation of oxidation products (cis,trans-hydroperoxy-octadecadienoates, cis,trans- and trans,trans-hydroxy-octadecadienoates). For the first time, the generation of hydroxy-octadecadienoates during in vitro digestion is reported. Furthermore, SPME-GC/MS study of non-digested and digested samples headspaces confirmed that lipid oxidation occurred: abundances of volatile markers increased (including potentially toxic alpha,beta-unsaturated aldehydes), especially in oxidized oils digestates. Markers of Maillard-type and esterification reactions were also detected in the digestates. Copyright © 2016 Elsevier Ltd. All rights reserved.

Maillard reaction products enriched food extract reduce the expression of myofibroblast phenotype markers.

PubMed

Ruhs, Stefanie; Nass, Norbert; Somoza, Veronika; Friess, Ulrich; Schinzel, Reinhard; Silber, Rolf-Edgar; Simm, Andreas

2007-04-01

Advanced glycation end products (AGE) are associated with a wide range of degenerative diseases. The present investigation aimed at analysing the influence of AGE containing nutritional extracts on cardiac fibroblasts (CFs) as the major cell type responsible for cardiac fibrosis. Mice CFs were treated with bread crust extract (BCE) which contained significant amounts of a variety of AGE modifications. BCE treatment with up to 30 mg/mL did not impair cell viability. Furthermore, BCE induced a moderate elevation of reactive oxygen species (ROS) production and activation of redox sensitive pathways like the p42/44(MAPK), p38(MAPK) and NF-kappaB but did not alter Akt kinase phosphorylation. Expression of smooth muscle alpha-actin and tropomyosin-1, which represent markers for myofibroblast differentiation, was reduced after bread crust treatment. These data suggest a putative antifibrotic effect of melanoidin-rich food.

Calcium-Magnesium-Aluminosilicate (CMAS) Reactions and Degradation Mechanisms of Advanced Environmental Barrier Coatings

NASA Technical Reports Server (NTRS)

Ahlborg, Nadia L.; Zhu, Dongming

2013-01-01

The thermochemical reactions between calcium-magnesium-aluminosilicate- (CMAS-) based road sand and several advanced turbine engine environmental barrier coating (EBC) materials were studied. The phase stability, reaction kinetics and degradation mechanisms of rare earth (RE)-silicates Yb2SiO5, Y2Si2O7, and RE-oxide doped HfO2 and ZrO2 under the CMAS infiltration condition at 1500 C were investigated, and the microstructure and phase characteristics of CMAS-EBC specimens were examined using Scanning Electron Microscopy (SEM) and X-ray Diffraction (XRD). Experimental results showed that the CMAS dissolved RE-silicates to form crystalline, highly non-stoichiometric apatite phases, and in particular attacking the silicate grain boundaries. Cross-section images show that the CMAS reacted with specimens and deeply penetrated into the EBC grain boundaries and formed extensive low-melting eutectic phases, causing grain boundary recession with increasing testing time in the silicate materials. The preliminary results also showed that CMAS reactions also formed low melting grain boundary phases in the higher concentration RE-oxide doped HfO2 systems. The effect of the test temperature on CMAS reactions of the EBC materials will also be discussed. The faster diffusion exhibited by apatite and RE-doped oxide phases and the formation of extensive grain boundary low-melting phases may limit the CMAS resistance of some of the environmental barrier coatings at high temperatures.

Reaction mechanisms of DNT with hydroxyl radicals for advanced oxidation processes-a DFT study.

PubMed

Zhou, Yang; Yang, Zhilin; Yang, Hong; Zhang, Chaoyang; Liu, Xiaoqiang

2017-04-01

In advanced oxidation processes (AOPs), the detailed degradation mechanisms of a typical explosive of 2,4-dinitrotoluene (DNT) can be investigated by the density function theory (DFT) method at the SMD/M062X/6-311+G(d) level. Several possible degradation routes for DNT were explored in the current study. The results show that, for oxidation of the methyl group, the dominant degradation mechanism of DNT by hydroxyl radicals (•OH) is a series of sequential H-abstraction reactions, and the intermediates obtained are in good agreement with experimental findings. The highest activation energy barrier is less than 20 kcal mol -1 . Other routes are dominated by an addition-elimination mechanism, which is also found in 2,4,6-trinitrotoluene, although the experiment did not find the corresponding products. In addition, we also eliminate several impossible mechanisms, such as dehydration, HNO 3 elimination, the simultaneous addition of two •OH radials, and so on. The information gained about these degradation pathways is helpful in elucidating the detailed reaction mechanism between nitroaromatic explosives and hydroxyl radicals for AOPs. Graphical Abstract The degradation mechanism of an important explosive, 2,6-dinitrotoluene (DNT), by the hydroxyl radical for advanced oxidation progresses.

Effect of theanine and polyphenols enriched fractions from decaffeinated tea dust on the formation of Maillard reaction products and sensory attributes of breads.

PubMed

Culetu, Alina; Fernandez-Gomez, Beatriz; Ullate, Monica; del Castillo, Maria Dolores; Andlauer, Wilfried

2016-04-15

The antiglycoxidative properties of theanine (TEF) and polyphenols enriched fractions (PEF) prepared from tea dust were tested in a model system composed of bovine serum albumin (BSA) and methylglyoxal (MGO). PEF caused a decrease in available free amino groups of BSA in presence and absence of MGO, suggesting the simultaneous occurrence of glycoxidation reaction and phenols-protein interaction. The presence of PEF and TEF inhibited formation of fluorescent advanced glycation end-products (AGEs). Moreover, theanine (TB) and polyphenol-enriched bread (PB) were formulated. A significant increase in free amino groups was observed in TBs with a dose-response effect, while addition of PEF in bread produced a significant decrease (p<0.05). PEF efficiently reduced fluorescent AGE formation in breads compared with TEF. The results are in line with the simplified model systems. PEF used as food ingredient allows obtaining a tasty food possessing health promoting properties and lower content of potential harmful compounds (AGEs). Copyright © 2015 Elsevier Ltd. All rights reserved.

Advanced glycation end products (AGEs) in oral pathology.

PubMed

Ilea, Aranka; Băbţan, Anida M; Boşca, Bianca A; Crişan, Maria; Petrescu, Nausica B; Collino, Massimo; Sainz, Rosa M; Gerlach, Jared Q; Câmpian, Radu Septimiu

2018-05-18

Maillard advanced glycation end products (AGEs) are connected with high dry temperature food processing, color and flavor modification of food products. Oral cavity pathology is strongly influenced by dietary intake. The aim of the present paper is to update current data regarding the sources and metabolism of AGEs, their impact on oral cavity tissues, to discuss and suggest new approaches for the early diagnosis and efficient treatment of AGEs-related oral pathology. This paper is a narrative review of the studies discussing AGEs and mainly the dietary AGEs (dAGEs) sources, metabolism, linkage to general diseases, and specifically the oral cavity pathology. The authors used "PUBMED" and MeSH for the finding of English written and published articles concerning AGEs. There were used the next keywords association: "advanced glycation end products- AGEs" AND "Maillard products", "AGEs" AND "diet-related disease, "AGEs" AND "salivary biosensor", "AGEs" AND "metabolic syndrome AGEs", "AGEs" AND "oral pathology", "AGEs" AND "dentin AGEs" OR "periodontal AGEs", "AGEs" AND "diagnosis and monitoring". The authors used free full-text articles to determine the etiology and physiopathology of AGEs, their association with general diseases and oral cavity disease, assessment methods used in biofluids and tissues, AGEs prevention and treatment approaches. Articles concerning AGEs etiology, metabolism and effect in the human body and specific implication in oral pathology were selected. There were no exclusion criteria in what concerns the study design. Studies in other language than English and articles abstracts were excluded. Criteria of inclusion were free full-text articles written in English. Equally human and animal model studies were included. Regarding the date of publication, all subjects concerning glycation products after 1953 (first published article) were included. Evidence show that AGEs are responsible for inducing low intensity chronic inflammation and thereby

Engineering and biotechnological aspects for the manufacturing of high quality fried potato products.

PubMed

Reimerdes, Ernst H; Franke, Knut

2006-04-01

Fried potato products have become very popular foods over the last decades. High quality standards have been established for these products by the food industry including uniform brown color and crispness. During frying, Maillard reactions takes place which contribute to color and taste development in these products. However, safety aspects are also influenced by these reactions, e.g., acrylamide formation. Maintaining high safety standards as well as the expected quality requires systematic research based on an integrated approach including all relevant variables, e.g., raw material properties, processing conditions and equipment concepts. Selected results of these investigations are presented and discussed, regarding influence of composition, e.g., precursor levels for Maillard reactions, treatment of raw materials and addition of reactants to frying fat. It has been demonstrated that a combined treatment of the potato sticks by coating of product surfaces and partial pre-drying can be successfully applied to produce well-browned French fries with lower acrylamide contents. Reductions up to 75% could be reached compared to samples without treatment. Furthermore, addition of a water/oil emulsion containing glutamine in the aqueous phase has been shown to influence Maillard reactions at the product surface, resulting in lower acrylamide contents at the same state of browning.

Glucosamine prevents in vitro collagen degradation in chondrocytes by inhibiting advanced lipoxidation reactions and protein oxidation

PubMed Central

Tiku, Moti L; Narla, Haritha; Jain, Mohit; Yalamanchili, Praveen

2007-01-01

Osteoarthritis (OA) affects a large segment of the aging population and is a major cause of pain and disability. At present, there is no specific treatment available to prevent or retard the cartilage destruction that occurs in OA. Recently, glucosamine sulfate has received attention as a putative agent that may retard cartilage degradation in OA. The precise mechanism of action of glucosamine is not known. We investigated the effect of glucosamine in an in vitro model of cartilage collagen degradation in which collagen degradation induced by activated chondrocytes is mediated by lipid peroxidation reaction. Lipid peroxidation in chondrocytes was measured by conjugated diene formation. Protein oxidation and aldehydic adduct formation were studied by immunoblot assays. Antioxidant effect of glucosamine was also tested on malondialdehyde (thiobarbituric acid-reactive substances [TBARS]) formation on purified lipoprotein oxidation for comparison. Glucosamine sulfate and glucosamine hydrochloride in millimolar (0.1 to 50) concentrations specifically and significantly inhibited collagen degradation induced by calcium ionophore-activated chondrocytes. Glucosamine hydrochloride did not inhibit lipid peroxidation reaction in either activated chondrocytes or in copper-induced oxidation of purified lipoproteins as measured by conjugated diene formation. Glucosamine hydrochloride, in a dose-dependent manner, inhibited malondialdehyde (TBARS) formation by oxidized lipoproteins. Moreover, we show that glucosamine hydrochloride prevents lipoprotein protein oxidation and inhibits malondialdehyde adduct formation in chondrocyte cell matrix, suggesting that it inhibits advanced lipoxidation reactions. Together, the data suggest that the mechanism of decreasing collagen degradation in this in vitro model system by glucosamine may be mediated by the inhibition of advanced lipoxidation reaction, preventing the oxidation and loss of collagen matrix from labeled chondrocyte matrix

Antiglycation and antioxidation properties of Juglans regia and Calendula officinalis: possible role in reducing diabetic complications and slowing down ageing.

PubMed

Ahmad, Haroon; Khan, Ibrar; Wahid, Abdul

2012-09-01

Accumulation of advanced glycation end products (AGEs) in the body due to the non-enzymatic glycation of proteins and oxidation is associated with aging and diabetes mellitus. In this study we wanted to investigate the antiglycation and antioxidation potential of two medicinal plants: Juglans regia and Calendula officinalis. In-vitro investigation was carried out to discover the antiglycation and antioxidation potential of J. regia and C. officinalis. Using an Ultraviolet Double-beam Spectrophotometer, we evaluated the antiglycation property of the crude methanolic extracts of J. regia and C. officinalis by assessing their ability to inhibit the Maillard reaction. Employing the same instrument we also measured the antioxidation potential of these plant extracts using the nitric oxide (NO) free radical-scavenging assay. J. regia had greater antiglycation ability, with a minimum inhibitory concentration (MIC50) of 28 microg/mL as compared with that of C. officinalis (270 microg/mL). C. officinalis had greater antioxidation potential (26.10, 22.07 and 16.06% at 0.5 mg, 0.25 mg and 0.125 mg, respectively, as compared with 18.15, 16.50 and 16.06% of J. regia, respectively). J. regia and C. officinalis inhibited the Maillard reaction and prevented oxidation in-vitro. Hence, the extracts of these plants could have therapeutic uses in curbing chronic diabetic complications and slowing down aging.

Recent advances in copper-catalyzed asymmetric coupling reactions

PubMed Central

2015-01-01

Summary Copper-catalyzed (or -mediated) asymmetric coupling reactions have received significant attention over the past few years. Especially the coupling reactions of aryl or alkyl halides with nucleophiles became a very powerful tool for the formation of C–C, C–N, C–O and other carbon–heteroatom bonds as well as for the construction of heteroatom-containing ring systems. This review summarizes the recent progress in copper-catalyzed asymmetric coupling reactions for the formation of C–C and carbon–heteroatom bonds. PMID:26734106

Changes in physical, chemical and functional properties of whey protein isolate (WPI) and sugar beet pectin (SBP) conjugates formed by controlled dry-heating

USDA-ARS?s Scientific Manuscript database

A Maillard type reaction in the dry state was utilized to create conjugates between whey protein isolate (WPI) and sugar beet pectin (SBP) to achieve improved functional properties including solubility, colloidal stability and oil-in-water emulsion stability. To optimize the reaction conditions, mi...

Heat damaged forages: effects on forage energy content

USDA-ARS?s Scientific Manuscript database

Traditionally, educational materials describing the effects of heat damage within baled hays have focused on reduced bioavailability of crude protein as a result of Maillard reactions. These reactions are not simple, but actually occur in complex, multi-step pathways. Typically, the initial step inv...

Chemical Changes in Proteins Produced by Thermal Processing.

ERIC Educational Resources Information Center

Dutson, T. R.; Orcutt, M. W.

1984-01-01

Discusses effects of thermal processing on proteins, focusing on (1) the Maillard reaction; (2) heat denaturation of proteins; (3) aggregation, precipitation, gelation, and degradation; and (4) other thermally induced protein reactions. Also discusses effects of thermal processing on muscle foods, egg proteins, fruits and vegetables, and cereal…

Iridoids from Carbohydrates via Pauson-Khand Reaction: Synthesis of Advanced Highly Oxygenated Cyclopentane-Annulated Pyranosides from D-Glucal Derivatives.

PubMed

Marco-Contelles, José; Ruiz-Caro, Juliana

1999-10-29

The Pauson-Khand reaction on suitable 4-oxa-hept-1-en-6-ynes (1, 17) obtained from 3,4,6-tri-O-acetyl-D-glucal gives the cyclopentane-annulated pyranosides (2, 18) that can be efficiently and stereoselectivelly transformed into chiral, advanced, highly oxygenated intermediates (10, 16, 24) for the synthesis of iridoid aglycones.

Development of microwave assisted spectrophotometric method for the determination of glucose

NASA Astrophysics Data System (ADS)

Ali, Asif; Hussain, Zahid; Arain, Muhammad Balal; Shah, Nasrullah; Khan, Khalid Mohammad; Gulab, Hussain; Zada, Amir

2016-01-01

A spectrophotometric method was developed based on the microwave assisted synthesis of Maillard product. Various conditions of the reaction were optimized by varying the relative concentration of the reagents, operating temperature and volume of solutions used in the reaction in the microwave synthesizer. The absorbance of the microwave synthesized Maillard product was measured in the range of 360-740 nm using UV-Visible spectrophotometer. Based on the maximum absorbance, 370 nm was selected as the optimum wave length for further studies. The LOD and LOQ of glucose was found 3.08 μg mL- 1 and 9.33 μg mL- 1 with standard deviation of ± 0.05. The developed method was also applicable to urine sample.

Role of Advanced Glycation Endproducts and Potential Therapeutic Interventions in Dialysis Patients

PubMed Central

Mallipattu, Sandeep K.; He, John C.; Uribarri, Jaime

2017-01-01

It has been nearly 100 years since the first published report of advanced glycation end products (AGEs) by the French chemist Maillard. Since then, our understanding of AGEs in diseased states has dramatically changed. Especially in the last 25 years, AGEs have been implicated in complications related to aging, neurodegenerative diseases, diabetes, and chronic kidney disease. Although AGE formation has been well characterized by both in vitro and in vivo studies, few prospective human studies exist demonstrating the role of AGEs in patients on chronic renal replacement therapy. As the prevalence of end-stage renal disease (ESRD) in the United States rises, it is essential to identify therapeutic strategies that either delay progression to ESRD or improve morbidity and mortality in this population. This article reviews the role of AGEs, especially those of dietary origin, in ESRD patients as well as potential therapeutic anti-AGE strategies in this population. PMID:22548330

Printing enzymatic reactions.

PubMed

Tian, Junfei; Shen, Wei

2011-02-07

We used relief and planographic printing methods to print the catalytic effect of an enzyme, but not the enzyme molecules, onto paper. Printing enzymatic reactions have applications in bioactive papers, low-cost diagnostics, anti-counterfeiting devices and advanced packaging materials. These methods can create novel printing effects on commodity surfaces for advanced applications.

Methylglyoxal-induced modification causes aggregation of myoglobin

NASA Astrophysics Data System (ADS)

Banerjee, Sauradipta; Maity, Subhajit; Chakraborti, Abhay Sankar

2016-02-01

Post-translational modification of proteins by Maillard reaction, known as glycation, is thought to be the root cause of different complications, particularly in diabetes mellitus and age-related disorders. Methylglyoxal (MG), a reactive α-oxoaldehyde, increases in diabetic condition and reacts with proteins to form advanced glycation end products (AGEs) following Maillard-like reaction. We have investigated the in vitro effect of MG (200 μM) on the monomeric heme protein myoglobin (Mb) (100 μM) in a time-dependent manner (7 to 18 days incubation at 25 °C). MG induces significant structural alterations of the heme protein, including heme loss, changes in tryptophan fluorescence, decrease of α-helicity with increased β-sheet content etc. These changes occur gradually with increased period of incubation. Incubation of Mb with MG for 7 days results in formation of the AGE adducts: carboxyethyllysine at Lys-16, carboxymethyllysine at Lys-87 and carboxyethyllysine or pyrraline-carboxymethyllysine at Lys-133. On increasing the period of incubation up to 14 days, additional AGEs namely, carboxyethyllysine at Lys-42 and hydroimidazolone or argpyrimidine at Arg-31 and Arg-139 have been detected. MG also induces aggregation of Mb, which is clearly evident with longer period of incubation (18 days), and appears to have amyloid nature. MG-derived AGEs may thus have an important role as the precursors of protein aggregation, which, in turn, may be associated with physiological complications.

The Maillard protein cross-link pentosidine in urine from diabetic patients.

PubMed

Takahashi, M; Ohishi, T; Aoshima, H; Kawana, K; Kushida, K; Inoue, T; Horiuchi, K

1993-07-01

The Maillard protein cross-link pentosidine is a fluorescent condensation product of lysine, arginine and ribose. It accumulates in human tissues with age, and the accumulation process is accelerated in the tissues of diabetic patients. Using SP-Sephadex C-25 in the pretreatment for HPLC, we examined levels of pentosidine in urine without hydrolysis (free form) and levels of pentosidine in urine after hydrolysis (total forms), from 23 diabetic patients and 21 control subjects. The mean percentages of the values of free form per total forms (+/- SD) were 89 +/- 15% in diabetic patients, 88 +/- 16% in control subjects and 89 +/- 15% in total populations of diabetic patients and control subjects. There was a significant correlation between the values of free form and total forms in diabetic patients (r = 0.983, p = 0.0001), in control subjects (r = 0.820, p < 0.02) and in total populations of diabetic patients and control subjects (r = 0.951, p = 0.0001). The mean level of pentosidine per mol creatinine (+/- SD) was significantly elevated in urine from diabetic patients as compared to the level in control subjects (8.8 +/- 4.3 mumol/mol creatinine vs 4.2 +/- 1.4 mumol/mol creatinine, p = 0.0001 in free form; 10.1 +/- 5.3 mumol/mol creatinine vs 4.7 +/- 1.4 mumol/mol creatinine, p = 0.0001 in total forms). These results demonstrate that urinary pentosidine, especially in free form, could be a useful marker for the assessment of diabetes and diabetic complications.

Studies on the inhibition of tumor cell growth and microtubule assembly by 3-hydroxy-4-[(E)-(2-furyl)methylidene]methyl-3-cyclopentene-1,2-dione, an intensively coloured Maillard reaction product.

PubMed

Marko, D; Kemény, M; Bernady, E; Habermeyer, M; Weyand, U; Meiers, S; Frank, O; Hofmann, T

2002-01-01

Very recently, 3-hydroxy-4-[(E)-(2-furyl)methylidene]methyl-3-cyclopentene-1,2-dione (1) has been successfully identified as an intensively coloured Maillard product formed from glucose and L-proline upon thermal food processing. Using a biomimetic synthetic strategy, reference material of compound 1 was prepared and purified, and then used to study its effect on the growth of human tumor cells. Compound 1 was found to potently inhibit the growth of human tumor cells in vitro. Using a reporter gene assay we could show that in growth inhibitory concentrations compound 1 effectively inhibits the phosphorylation of the transcription factor Elk-1. In addition, 1 was found to affect the microtubule skeleton. The human mammary carcinoma cell line MCF-7 exhibits a decrease of the microtubule organisation when treated for 24 h with 1 (> or =20 microM). At concentrations of 30 microM and above a loss of microtubule integrity is observed after 1 h incubation. In vitro studies demonstrated that the polymerisation and, to a minor extent, also the depolymerisation of tubulin, isolated and purified from bovine brain, is inhibited in a dose-dependent manner at concentrations of 30 microM and above. This is the first time that a non-enzymatically formed browning compound of known structure was reported to effectively inhibit tumor cell growth and microtubule assembly.

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions

PubMed Central

Menon, Rajeev S; Biju, Akkattu T

2016-01-01

Summary N-Heterocyclic carbenes (NHCs) have emerged as a powerful class of organocatalysts that mediate a variety of organic transformations. The Benzoin reaction constitutes one of the earliest known carbon–carbon bond-forming reactions catalysed by NHCs. The rapid growth of NHC catalysis in general has resulted in the development of a variety of benzoin and benzoin-type reactions. An overview of such NHC-catalysed benzoin reactions is presented. PMID:27340440

Recent advances in N-heterocyclic carbene (NHC)-catalysed benzoin reactions.

PubMed

Menon, Rajeev S; Biju, Akkattu T; Nair, Vijay

2016-01-01

N-Heterocyclic carbenes (NHCs) have emerged as a powerful class of organocatalysts that mediate a variety of organic transformations. The Benzoin reaction constitutes one of the earliest known carbon-carbon bond-forming reactions catalysed by NHCs. The rapid growth of NHC catalysis in general has resulted in the development of a variety of benzoin and benzoin-type reactions. An overview of such NHC-catalysed benzoin reactions is presented.

Formation of furan and methylfuran by maillard-type reactions in model systems and food.

PubMed

Limacher, Anita; Kerler, Josef; Davidek, Tomas; Schmalzried, Frank; Blank, Imre

2008-05-28

The formation of furan and 2-methylfuran was studied in model systems based on sugars and selected amino acids. Both compounds were preferably formed under roasting conditions in closed systems yielding up to 330 micromol of furan and 260 micromol of 2-methylfuran per mol of precursor. The amounts obtained under pressure cooking conditions were much lower, usually below 20 micromol/mol, except for 2-furaldehyde, which yielded 70-100 micromol/mol of furan. Labeling studies indicated two major formation pathways for both furans: (i) from the intact sugar skeleton and (ii) by recombination of reactive C(2) and/or C(3) fragments. Under roasting conditions in the absence of amino acids, furan was mainly formed from the intact sugar skeleton. Formic and acetic acid were identified as byproducts of sugar degradation, indicating the split off of C(1) and/or C(2) units from hexoses. The presence of alanine, threonine, or serine promoted furan formation by the recombination of C(2) fragments, such as acetaldehyde and glycolaldehyde, which may originate from both sugars and amino acids. In aqueous solution, about half of furan was generated by the recombination of sugar fragments. 2-Methylfuran was preferably formed in the presence of amino acids by aldol-type reactions of C(2) and C(3) fragments with lactaldehyde as a key intermediate, the Strecker aldehyde of threonine. The total furan levels in cooked vegetables were increased by spiking with hexoses. However, in pumpkin puree, only about 20% of furan was formed from sugars, preferably from the intact carbon skeleton.

Role of advanced glycation endproducts and potential therapeutic interventions in dialysis patients.

PubMed

Mallipattu, Sandeep K; He, John C; Uribarri, Jaime

2012-01-01

It has been nearly 100 years since the first published report of advanced glycation end products (AGEs) by the French chemist Maillard. Since then, our understanding of AGEs in diseased states has dramatically changed. Especially in the last 25 years, AGEs have been implicated in complications related to aging, neurodegenerative diseases, diabetes, and chronic kidney disease. Although AGE formation has been well characterized by both in vitro and in vivo studies, few prospective human studies exist demonstrating the role of AGEs in patients on chronic renal replacement therapy. As the prevalence of end-stage renal disease (ESRD) in the United States rises, it is essential to identify therapeutic strategies that either delay progression to ESRD or improve morbidity and mortality in this population. This article reviews the role of AGEs, especially those of dietary origin, in ESRD patients as well as potential therapeutic anti-AGE strategies in this population. © 2012 Wiley Periodicals, Inc.

Systemic activation of NF-κB driven luciferase activity in transgenic mice fed advanced glycation end products modified albumin.

PubMed

Nass, Norbert; Bayreuther, Kristina; Simm, Andreas

2017-04-01

Advanced glycation end products (AGEs) are stable end products of the Maillard reaction and accumulate with progressing ageing and degenerative diseases. Significant amounts of AGE-modified peptides are also consumed with processed food. AGEs bind to specific receptors, especially the receptor of AGEs (RAGE). Activation of RAGE then evokes intracellular signalling, finally resulting in the activation of the NF-κB transcription factor and therefore a proinflammatory state. We here analysed, whether NF-κB is activated in short term upon feeding an AGE-modified protein in-vivo. Transgenic mice expressing firefly luciferase under the control of an NF-κB responsive promoter were intraperitoneally injected or fed with AGE-modified- or control albumin and luciferase expression was analysed by in-vivo imaging and by in-vitro by determination of luciferase enzyme activity in heart, lung, gut, spleen, liver and kidney. In all organs, an activation of the luciferase reporter gene was observed in response to AGE-BSA feeding, however with different intensity and timing. The gut exhibited highest luciferase activity and this activity peaked 6-8 h post AGE-feeding. In heart and kidney, luciferase activity increased for up to 12 h post feeding. All other organs tested, exhibited highest activity at 10 h after AGE-consumption. Altogether, these data demonstrate that feeding AGE-modified protein resulted in a transient and systemic activation of the NF-κB reporter.

Development of a heat-processing method for koji to enhance its antioxidant activity.

PubMed

Okutsu, Kayu; Yoshizaki, Yumiko; Takamine, Kazunori; Tamaki, Hisanori; Ito, Kiyoshi; Sameshima, Yoshihiro

2012-03-01

We developed a heat-processing method to enhance the antioxidant activity of koji. The superoxide anion scavenging activity (SOSA) and oxygen radical absorbance capacity (ORAC) of heat-processed koji (HP-koji) at 55 °C for 7 days were 4.9 times and 4.2 times, respectively, those of unheated koji. These results showed that heat processing effectively enhances the antioxidant activity of koji. Analysis of the antioxidant activities of koji subjected to a range of temperatures (45-75 °C) revealed that the SOSA is enhanced by heating at higher temperatures, which might be catalyzed by Maillard reaction, whereas the ORAC was enhanced by heating at lower temperatures, which might be catalyzed by an enzymatic reaction. Assuming these enhancements in antioxidant activities are contributed by both Maillard and enzyme reactions, we hypothesized that the antioxidant activity of HP-koji could be more effectively amplified by heating at a higher temperature after the progression of the enzymatic reaction at a moderate temperature. Therefore, we evaluated the effect of heating of koji in a stepwise manner, first at 55 °C for 2 days and then at 75 °C for 5days. The antioxidant activities of stepwise-heated HP-koji were higher than those of koji heated at either 55 °C or 75 °C. The SOSA and ORAC of stepwise-heated HP-koji were 94 times and 6 times, respectively, those of unheated koji. This result suggests that enzymatic reaction followed by Maillard reaction can effectively enhance the antioxidant activity of HP-koji. Thus, we developed a novel heat-processing method to enhance the antioxidant activity of koji. Copyright © 2011 The Society for Biotechnology, Japan. Published by Elsevier B.V. All rights reserved.

Investigation of CO2 precursors in roasted coffee.

PubMed

Wang, Xiuju; Lim, Loong-Tak

2017-03-15

Two CO 2 formation pathways (chlorogenic acid (CGA) degradation and Maillard reaction) during coffee roasting were investigated. CGA is shown not a major contributor to CO 2 formation, as heating of this compound under typical roasting conditions did not release a large quantity of CO 2 . However, heating of a CGA moiety, caffeic acid, resulted in high yield of CO 2 (>98%), suggesting that CGA hydrolysis could be the rate limiting step for CO 2 formation from CGA. A large amount of CO 2 was detected from glycine-sucrose model system under coffee roasting conditions, implying the importance of Maillard reactions in CO 2 formation. Further studies on the heating of various components isolated from green coffee beans showed that CO 2 was generated from various green coffee components, including water insoluble proteins and polysaccharides. Around 50% of CO 2 was formed from thermal reactions of lower molecular weight compounds that represent ∼25% by weight in green coffee. Copyright © 2016 Elsevier Ltd. All rights reserved.

Glycation of β-lactoglobulin and antiglycation by genistein in different reactive carbonyl model systems.

PubMed

Kong, Yanghui; Li, Xiaoming; Zheng, Tiesong; Lv, Lishuang

2015-09-15

Advanced glycation end products (AGEs), which are formed in β-lactoglobulin (β-lg) glycation systems via the Maillard reaction, have been implicated in diabetes-related long-term complications. In the present study, we found that reaction conditions, including temperature, time, pH, reactant type and molar ratio of beta-lg to a sugar/MGO/GO, can significantly affect the formation of AGEs. Using SDS-PAGE, we further demonstrated that genistein, a natural isoflavone found in a number of plants including soybeans and kudzu, can efficiently inhibit cross-links of the glycated β-lg, and suppress the formation AGEs in a dose-dependent manner by trapping reactive dicarbonyl compounds. The products formed from genistein and methylglyoxal (MGO) in the β-lg-MGO assay were analyzed using LC/MS. Both mono-MGO and di-MGO adducts of genistein were detected with this method. Copyright © 2015 Elsevier Ltd. All rights reserved.

Advances in chemoselective intermolecular cross-benzoin-type condensation reactions.

PubMed

Gaggero, Nicoletta; Pandini, Stefano

2017-08-23

The intermolecular cross-benzoin and acyloin condensation reactions are powerful approaches to α-hydroxy carbonyls in a single step. However, their potentiality suffers from the occurrence of side reactions including self-condensation and the formation of the undesired cross-acyloin. The broad range of azolium salt precatalysts available confers high tunability to NHC mediated benzoin condensation, assuring a good level of selectivity to the direct coupling between two non-equivalent aldehydes. Many efforts have also been devoted to the design of strategies that expand the range of suitable reaction partners beyond the traditional aldehydes and to the discovery of novel umpolung catalytic systems. The synthesis of both racemic and enantiomerically enriched acyloins is reviewed.

Detection of AGEs as markers for carbohydrate metabolism and protein denaturation.

PubMed

Nagai, Ryoji; Shirakawa, Jun-Ichi; Fujiwara, Yukio; Ohno, Rei-Ichi; Moroishi, Narumi; Sakata, Noriyuki; Nagai, Mime

2014-07-01

Approximately 100 years have passed since the Maillard reaction was first reported in the field of food chemistry as a condensation reaction between reducing sugars and amino acids. This reaction is thought to progress slowly primarily from glucose with proteins in vivo. An early-stage product, called the "Amadori product", is converted into advanced glycation end products. Those accumulate in the body in accordance with age, with such accumulation being enhanced by lifestyle-related diseases that result in the denaturation of proteins. Recent studies have demonstrated that intermediate carbonyls are generated by several pathways, and rapidly generate many glycation products. However, accurate quantification of glycation products in vivo is difficult due to instability and differences in physicochemical properties. In this connection, little is known about the relationship between the structure of glycation products and pathology. Furthermore, the interaction between proteins modified by glycation and receptors for advanced glycation end products is also known to induce the production of several inflammatory cytokines. Therefore, those inhibitors have been developed over the world to prevent lifestyle-related diseases. In this review, we describe the process of protein denaturation induced by glycation and discuss the possibility of using the process as a marker of age-related diseases.

Fructosamine: Structure, Analysis, and Clinical Usefulness

DTIC Science & Technology

1987-09-09

reaction of amino acids and reducing sugars to fbrm The nonenzymatic glycation of hemoglobin having been stable ketoamine adducts (5). The Maillard ...clature for any reaction linking a sugar to a protein (I1 control. Unlike glycated hemoglobin, which reflects the aver- Thus "glycated" protein is...fructosamine is a ketoamine, a derivative of the nonenzy- Introduction matic reaction product of a sugar (usually glucose) and a protein (usually

Ion-Molecule Reaction Dynamics

NASA Astrophysics Data System (ADS)

Meyer, Jennifer; Wester, Roland

2017-05-01

We review the recent advances in the investigation of the dynamics of ion-molecule reactions. During the past decade, the combination of single-collision experiments in crossed ion and neutral beams with the velocity map ion imaging detection technique has enabled a wealth of studies on ion-molecule reactions. These methods, in combination with chemical dynamics simulations, have uncovered new and unexpected reaction mechanisms, such as the roundabout mechanism and the subtle influence of the leaving group in anion-molecule nucleophilic substitution reactions. For this important class of reactions, as well as for many fundamental cation-molecule reactions, the information obtained with crossed-beam imaging is discussed. The first steps toward understanding micro-solvation of ion-molecule reaction dynamics are presented. We conclude with the presentation of several interesting directions for future research.

The Catalytic Asymmetric Intramolecular Stetter Reaction

PubMed Central

de Alaniz, Javier Read; Rovis, Tomislav

2010-01-01

This account chronicles our efforts at the development of a catalytic asymmetric Stetter reaction using chiral triazolium salts as small molecule organic catalysts. Advances in the mechanistically related azolium-catalyzed asymmetric benzoin reaction are discussed, particularly as they apply to catalyst design. A chronological treatise of reaction discovery, catalyst optimization and reactivity extension follows. PMID:20585467

Glycosylated a-lactalbumin-based nanocomplex for curcumin: physicochemical stability and DPPH-scavenging activity

USDA-ARS?s Scientific Manuscript database

Low stability at high salt concentrations, iso-electric point, and high temperature restricted the application of proteins as stabilizers in nutraceutical encapsulation. Protein-polysaccharide conjugates made with Maillard reaction may be better alternatives. In this study, the characteristics of cu...

Recent advances in quantum scattering calculations on polyatomic bimolecular reactions.

PubMed

Fu, Bina; Shan, Xiao; Zhang, Dong H; Clary, David C

2017-12-11

This review surveys quantum scattering calculations on chemical reactions of polyatomic molecules in the gas phase published in the last ten years. These calculations are useful because they provide highly accurate information on the dynamics of chemical reactions which can be compared in detail with experimental results. They also serve as quantum mechanical benchmarks for testing approximate theories which can more readily be applied to more complicated reactions. This review includes theories for calculating quantities such as rate constants which have many important scientific applications.

Evidence of a glycemic threshold for the formation of pentosidine in diabetic dog lens but not in collagen.

PubMed

Nagaraj, R H; Kern, T S; Sell, D R; Fogarty, J; Engerman, R L; Monnier, V M

1996-05-01

The relationship between long-term glycemic control and the advanced Maillard reaction was investigated in dura mater collagen and lens proteins from dogs that were diabetic for 5 years. Diabetic dogs were assigned prospectively to good, moderate, and poor glycemic control and maintained by insulin. Biochemical changes were determined at study exit. Mean levels of collagen digestibility by pepsin decreased (NS) whereas collagen glycation (P < 0.001), pentosidine cross-links (P < 0.001), and collagen fluorescence (P = 0.02) increased with increasing mean HbA1 values. Similarly, mean levels of lens crystallin glycation (P < 0.001), fluorescence (P < 0.001), and the specific advanced lens Maillard product 1 (LM-1) (P < 0.001) and pentosidine (P < 0.005) increased significantly with poorer glycemic control. Statistical analysis revealed very high Spearman correlation coefficients between collagen and lens changes. Whereas pentosidine cross-links were significantly elevated in collagen from diabetic dogs with moderate levels of HbA1 (i.e., 8.0 +/- 0.4%), lens pentosidine levels were normal in this group and were elevated (P < 0.001) only in the animals with poor glycemic control (HbA1 = 9.7 +/- 0.6%). Thus, whereas protein glycation and advanced glycation in the extracellular matrix and in the lens are generally related to the level of glycemic control, there is evidence for a tissue-specific glycemic threshold for pentosidine formation, i.e., glycoxidation, in the lens. This threshold may be in part linked to a dramatic acceleration in crystallin glycation with HbA1 values of > 8.0% and/or a loss of lens membrane permeability. This study provides support at the molecular level for the growing concept that glycemic thresholds may be involved in the development of some of the complications in diabetes.

Progress and successes of the Specialty Crop Research Initiative on acrylamide reduction in processed potato products

USDA-ARS?s Scientific Manuscript database

Acrylamide, a suspected human carcinogen, is a Maillard reaction product that forms when carbohydrate-rich foods are cooked at high temperatures. Processed potato products, including French fries and potato chips, make a substantial contribution to total dietary acrylamide. Health safety concerns ra...

Update on the National Acrylamide Project

USDA-ARS?s Scientific Manuscript database

Acrylamide, a suspected human carcinogen that may delay fetal development, is a Maillard reaction product that forms when carbohydrate-rich foods are cooked at high temperatures. Processed potato products, including French fries and potato chips, make a substantial contribution to total dietary acry...

Heat Damaged Forages: Effects on Forage Quality

USDA-ARS?s Scientific Manuscript database

Traditionally, heat damage in forages has been associated with alterations in forage protein quality as a result of Maillard reactions, and most producers and nutritionists are familiar with this concept. However, this is not necessarily the most important negative consequence of spontaneous heating...

Genetic, Physiological, and Environmental Factors Affecting Acrylamide Concentration in Fried Potato Products

USDA-ARS?s Scientific Manuscript database

The discovery of acrylamide in processed potato products has brought increased interest in the controlling Maillard reaction precursors (reducing sugars and amino acids) in potato tubers. Because of their effects on nonenzymatic browning of fried potato products, reducing sugars and amino acids have...

Controlled release of B-carotene in B-lactoglobulin-dextran conjugates nanoparticles in vitro digestion and the transport with Caco-2 monolayers

USDA-ARS?s Scientific Manuscript database

Undesirable aggregation of nanoparticles stabilized by proteins may may occur at the protein’s isoelectric point when the particle has zero net charge. Aggregation may be reduced bychanging the isoelectric point by conjugation of free amino groups with reducing sugars (Maillard reaction). Alternativ...

[Identification of alkylbenzenes being formed in the model reaction of ribose with lysine].

PubMed

Biller, Elzbieta

2012-01-01

While studying volatile compounds in model experiments which simulated the broiling of meat (the reactions of ribose with lysine), there were alkylbenzenes identified. They belong to food contaminants and they could be originated from the detergents and petroleum as well as geochemical samples, but they were also obtained in Maillard reactions. The aim of the studies was the attempt of the alkylbenzenes identification being formed in the model reaction of ribose with lysine. Aqueous solutions of ribose and lysine (at concentration of 0.1 mol/dm3 each) were mixed in equal volumes 10 cm3 + 10 cm3. The pH of the mixtures were adjusted to 5.6 using citrate-phosphorous buffer. In that way conditions simulating pH of meat were obtained. The mixtures were heated inside the gastronomic roaster during 0, 5, 10, 15, 30, 45 and 60 minutes respectively, at the temperature 185 +/- 5 degrees C. After reactions, in the mixtures, the profiles of volatile compounds, including alkylbenzenes, were analyzed by GC-MS method. The compounds were being identified by: comparing each mass spectrum (MS) with spectra from the known libraries of MS; calculating the linear retention indexes (LRI); seeking similar LRI values of analogue compounds in literature. Amounts of volatiles were calculated in relation to amount of internal standard (IS) [-], dividing the area of the compound by area of IS. The kinds and amounts of alkylbenzenes depended on the duration of the reaction time. Maximally 16 various alkylbenzenes were developed. More of these compounds could be identified with the probability of 85-90%, using only MS, because of the lack information in literature. Moreover, the multi-dimensional GCxGC-MS or other chromatographic methods in order to make these compounds being better explored seems to be advisable. The identification of the compounds being formed during broiling of meat is very important, because of the fact that many of arising substances are considered to be unhealthy and

The role of advanced reactive surface area characterization in improving predictions of mineral reaction rates

NASA Astrophysics Data System (ADS)

Beckingham, L. E.; Zhang, S.; Mitnick, E.; Cole, D. R.; Yang, L.; Anovitz, L. M.; Sheets, J.; Swift, A.; Kneafsey, T. J.; Landrot, G.; Mito, S.; Xue, Z.; Steefel, C. I.; DePaolo, D. J.; Ajo Franklin, J. B.

2014-12-01

Geologic sequestration of CO2 in deep sedimentary formations is a promising means of mitigating carbon emissions from coal-fired power plants but the long-term fate of injected CO2 is challenging to predict. Reactive transport models are used to gain insight over long times but rely on laboratory determined mineral reaction rates that have been difficult to extrapolate to field systems. This, in part, is due to a lack of understanding of mineral reactive surface area. Many models use an arbitrary approximation of reactive surface area, applying orders of magnitude scaling factors to measured BET or geometric surface areas. Recently, a few more sophisticated approaches have used 2D and 3D image analyses to determine mineral-specific reactive surface areas that account for the accessibility of minerals. However, the ability of these advanced surface area estimates to improve predictions of mineral reaction rates has yet to be determined. In this study, we fuse X-ray microCT, SEM QEMSCAN, XRD, SANS, and SEM-FIB analysis to determine mineral-specific accessible reactive surface areas for a core sample from the Nagaoka pilot CO2 injection site (Japan). This sample is primarily quartz, plagioclase, smectite, K-feldspar, and pyroxene. SEM imaging shows abundant smectite cement and grain coatings that decrease the fluid accessibility of other minerals. However, analysis of FIB-SEM images reveals that smectite nano-pores are well connected such that access to underlying minerals is not occluded by smectite coatings. Mineral-specific accessible surfaces are determined, accounting for the connectivity of the pore space with and without connected smectite nano-pores. The large-scale impact of variations in accessibility and dissolution rates are then determined through continuum scale modeling using grid-cell specific information on accessible surface areas. This approach will be compared with a traditional continuum scale model using mineral abundances and common surface area

Application of the Organic Synthetic Designs to Astrobiology

NASA Astrophysics Data System (ADS)

Kolb, V. M.

2009-12-01

In this paper we propose a synthesis of the heterocyclic compounds and the insoluble materials on the meteorites. Our synthetic scheme involves the reaction of sugars and amino acids, the so-called Maillard reaction. We have developed this scheme based on the combined analysis of the regular and retrosynthetic organic synthetic principles. The merits of these synthetic methods for the prebiotic design are addressed.

Assessment of taurine bioavailability in pelleted and extruded diets with red drum Sciaenops ocellatus

USDA-ARS?s Scientific Manuscript database

Taurine has been reported to be efficacious in supporting growth of carnivorous fish species, particularly when supplemented to diets primarily containing plant feedstuffs. Although taurine may become unavailable to some extent by heat and moisture, and is susceptible to the Maillard reaction with r...

Advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects.

PubMed

Sicherer, Scott H; Leung, Donald Y M

2005-07-01

This review highlights some of the research advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects that were reported primarily in the Journal in 2004. Clinical observations included that gastrointestinal symptoms during anaphylaxis are associated with an increased risk for hypotension; recurrence of peanut allergy can occur for about 8% of children who pass an oral food challenge and is associated with continued avoidance of the food after the challenge; seafood allergy is reported by 2.3% of the US population; and determination of the time to resolution of childhood egg and milk allergy might be predictable by means of serial determination of food-specific IgE levels. The comorbid effects of atopic dermatitis (AD) on asthma and the role of topical calcineurin inhibitors in the therapy of AD were also addressed. Basic and translational research observations indicate that improved diagnosis and therapy might become possible on the basis of reported identification or characterization of allergens such as: lipid transfer proteins and birch pollen-related cross-reactive allergens in plant foods; proteins in scorpion venom that cross-react with proteins from imported fire ant; mosquito saliva proteins responsible for systemic anaphylaxis; and IgE binding to quinolones detectable with an in vitro immunoassay. In addition, advances in understanding immune regulation associated with abrogation of oral tolerance in food allergy and of dendritic cell function, modulation of regulatory T cells, and chemokine expression in AD have elucidated possible targets for future intervention.

The Analysis of AGEs and ALEs by Mass Spectrometry: What does the Future Hold?

DOE Office of Scientific and Technical Information (OSTI.GOV)

Metz, Thomas O.

2009-09-15

In 1912, Louis-Camille Maillard described a reaction between amino acids and reducing sugars that produced a discolored (brown) reaction mixture in the presence of heat [1]. This complex network of reactions between reducing sugars and free amine groups on amino acids or proteins came to be known as the Maillard reaction and was the domain of food chemists for the next 50 years. Work in the 1960s began a very exciting era in the field. A few years earlier, several groups [2-5] reported on the heterogeneity of normal human adult hemoglobin (HbA) as determined chromatographically, and Allen et al weremore » the first to use cation-exchange chromatography to separate a previously observed fast moving component (HbAI) into three fractions that they termed AIa, AIb, and AIc. An increase in the fast moving HbAI of four diabetic patients was subsequently reported by Huisman and Dozy in 1962 [6], and the link between diabetes and increased HbAI was later strengthened by Rahbar’s observation of increased HbAI – the majority of which is HbAIc – in 47 cases of diabetes [7]. Bookchin and Gallop determined that HbAIc consisted of a hexose bound to both β-chains [8], and Bunn and colleagues subsequently proposed that glucose binds to the N-terminal amine groups of the β-chain valine residues in the form of a Schiff base, which then rearranges to form an Amadori compound [9]. Thus, while Maillard chemistry was known to occur during the heating and processing of food, the identification of Amadori-modified hemoglobin proved that it also occurred in vivo (after all, as John Baynes likes to point out, humans are essentially low temperature ovens with long cooking cycles!).« less

Entropy Generation in a Chemical Reaction

ERIC Educational Resources Information Center

Miranda, E. N.

2010-01-01

Entropy generation in a chemical reaction is analysed without using the general formalism of non-equilibrium thermodynamics at a level adequate for advanced undergraduates. In a first approach to the problem, the phenomenological kinetic equation of an elementary first-order reaction is used to show that entropy production is always positive. A…

Advanced Organic Chemistry: Reactions and Mechanisms (by Bernard Miller)

NASA Astrophysics Data System (ADS)

Berger, Daniel

1998-12-01

Prentice Hall: Upper Saddle River, NJ, 1998. 338 pp, index. ISBN 0-13-373275-4. $59.00. Recently several short texts on intermediate organic chemistry have been published, intended for use in one-term courses for advanced undergraduates and for graduate students who need more background before taking a graduate-level course. These books fill a need not fully met by graduate-level texts such as Lowry and Richardson's Mechanism and Theory in Organic Chemistry or Carey and Sundberg's Advanced Organic Chemistry.

Reactions and properties of clusters

NASA Astrophysics Data System (ADS)

Castleman, A. W., Jr.

1992-09-01

The elucidation from a molecular point of view of the differences and similarities in the properties and reactivity of matter in the gaseous compared to the condensed state is a subject of considerable current interest. One of the promising approaches to this problem is to utilize mass spectrometry in conjunction with laser spectroscopy and fast-flow reaction devices to investigate the changing properties, structure and reactivity of clusters as a function of the degree of solvation under well-controlled conditions. In this regard, an investigation of molecular cluster ions has provided considerable new insight into the basic mechanisms of ion reactions within a cluster, and this paper reviews some of the recent advances in cluster production, the origin of magic numbers and relationship to cluster ion stabilities, and solvation effects on reactions. There have been some notable advances in the production of large cluster ions under thermal reaction conditions, enabling a systematic study of the influence of solvation on reactions to be carried out. These and other new studies of magic numbers have traced their origin to the thermochemical stability of cluster ions. There are several classes of reaction where solvation has a notable influence on reactivity. A particularly interesting example comes from recent studies of the reactions of the hydroxyl anion with CO2 and SO2, studied as a function of the degree of hydration of OH-. Both reactions are highly exothermic, yet the differences in reactivity are dramatic. In the case of SO2, the reaction occurs at near the collision rate. By contrast, CO2 reactivity plummets dramatically for clusters having more than four water molecules. The slow rate is in accord with observations in the liquid phase.

Extensive Variation in Fried Chip Color and Tuber Composition in Cold-Stored Tubers of Wild Potato (Solanum) Germplasm

USDA-ARS?s Scientific Manuscript database

Cold-induced sweetening and browning in the Maillard reaction have driven extensive research in the areas of plant physiology, biochemistry, and food science in Solanum tuberosum. To date, research in these areas excluded wild relatives of potato. This is the first assessment of cold-stored tuber c...

Acrylamide in processed potato products

USDA-ARS?s Scientific Manuscript database

Trace amounts of acrylamide are found in many foods cooked at high temperatures. Acrylamide in processed potato products is formed from reducing sugars and asparagine and is a product of the Maillard reaction. Processed potato products including fries and chips are relatively high in acrylamide comp...

An invertebrate hyperglycemic model for the identification of anti-diabetic drugs.

PubMed

Matsumoto, Yasuhiko; Sumiya, Eriko; Sugita, Takuya; Sekimizu, Kazuhisa

2011-03-30

The number of individuals diagnosed with type 2 diabetes mellitus, which is caused by insulin resistance and/or abnormal insulin secretion, is increasing worldwide, creating a strong demand for the development of more effective anti-diabetic drugs. However, animal-based screening for anti-diabetic compounds requires sacrifice of a large number of diabetic animals, which presents issues in terms of animal welfare. Here, we established a method for evaluating the anti-diabetic effects of compounds using an invertebrate animal, the silkworm, Bombyx mori. Sugar levels in silkworm hemolymph increased immediately after feeding silkworms a high glucose-containing diet, resulting in impaired growth. Human insulin and 5-aminoimidazole-4-carboxamide-1-β-D-ribofuranoside (AICAR), an AMP-activated protein kinase (AMPK) activator, decreased the hemolymph sugar levels of the hyperglycemic silkworms and restored growth. Treatment of the isolated fat body with human insulin in an in vitro culture system increased total sugar in the fat body and stimulated Akt phosphorylation. These responses were inhibited by wortmannin, an inhibitor of phosphoinositide 3 kinase. Moreover, AICAR stimulated AMPK phosphorylation in the silkworm fat body. Administration of aminoguanidine, a Maillard reaction inhibitor, repressed the accumulation of Maillard reaction products (advanced glycation end-products; AGEs) in the hyperglycemic silkworms and restored growth, suggesting that the growth defect of hyperglycemic silkworms is caused by AGE accumulation in the hemolymph. Furthermore, we identified galactose as a hypoglycemic compound in jiou, an herbal medicine for diabetes, by monitoring its hypoglycemic activity in hyperglycemic silkworms. These results suggest that the hyperglycemic silkworm model is useful for identifying anti-diabetic drugs that show therapeutic effects in mammals.

Application of muscadine grape (Vitis rotundifolia Michx.) pomace extract to reduce carcinogenic acrylamide.

PubMed

Xu, Changmou; Yagiz, Yavuz; Marshall, Sara; Li, Zheng; Simonne, Amarat; Lu, Jiang; Marshall, Maurice R

2015-09-01

Acrylamide is a byproduct of the Maillard reaction and is formed in a variety of heat-treated commercial starchy foods. It is known to be toxic and potentially carcinogenic to humans. Muscadine grape polyphenols and standard phenolic compounds were examined on the reduction of acrylamide in an equimolar asparagine/glucose chemical model, a potato chip model, and a simulated physiological system. Polyphenols were found to significantly reduce acrylamide in the chemical model, with reduced rates higher than 90% at 100 μg/ml. In the potato chip model, grape polyphenols reduced the acrylamide level by 60.3% as concentration was increased to 0.1%. However, polyphenols exhibited no acrylamide reduction in the simulated physiological system. Results also indicated no significant correlation between the antioxidant activities of polyphenols and their acrylamide inhibition. This study demonstrated muscadine grape extract can mitigate acrylamide formation in the Maillard reaction, which provides a new value-added application for winery pomace waste. Copyright © 2015 Elsevier Ltd. All rights reserved.

Effects of certain polyphenols and extracts on furans and acrylamide formation in model system, and total furans during storage.

PubMed

Oral, Rasim Alper; Dogan, Mahmut; Sarioglu, Kemal

2014-01-01

Using a glucose-glycine and asparagine-fructose system as a Maillard reaction model, the effects of seven polyphenols and solid phase extracts of three plants on the formation of furans and acrylamide were investigated. The polyphenols and extracts were used in biscuit formulation and acrylamide formation was observed. They were used for the storage of the glycine-glucose model system at three different temperatures. The addition of some of the extracts and polyphenols significantly decreased furan formation to different extents. All phenolic compounds and plant extracts decreased in the range of 30.8-85% in the model system except for oleuropein, and all of them decreased in the range of 10.3-19.2% in biscuit. Total furan formation was inhibited by caffeic acid, punicalagin, epicatechin, ECE and PPE during storage. This study evaluated and found the inhibitory effect on the formation of furans and acrylamide in Maillard reactions by the use of some plant extracts and polyphenols. Copyright © 2013 Elsevier Ltd. All rights reserved.

Influence of temperature on nitrogen fate during hydrothermal carbonization of food waste.

PubMed

Wang, Tengfei; Zhai, Yunbo; Zhu, Yun; Peng, Chuan; Xu, Bibo; Wang, Tao; Li, Caiting; Zeng, Guangming

2018-01-01

The influence of temperature (180-260°C) on the fate of nitrogen during hydrothermal carbonization (HTC) of food waste (FW) was assessed. The distribution and evolution of nitrogen in aqueous products and bio-oil, as well as hydrochar, were conducted. Results suggested that elevated temperature enhanced the deamination and the highest ammonium concentration (929.75mg/L) was acquired at 260°C. At temperatures above 220°C, the total N in the hydrochar became stable, whereas the mass percentage of N increased. Amines and heterocyclic-N compounds from protein cracking and Maillard reactions were identified as the main nitrogen-containing compounds in the bio-oil. As to the hydrochar, increasing temperature resulted in condensed nitrogen-containing aromatic heterocycles (e.g. pyridine-N and quaternary-N). In particular, remarkable Maillard reactions at 180°C and the highest temperature at 260°C enhanced nitrogen incorporation (i.e. quaternary-N) into hydrochar. Copyright © 2017 Elsevier Ltd. All rights reserved.

Influence of Sulfur Fertilization on the Antioxidant Activities of Onion Juices Prepared by Thermal Treatment

PubMed Central

Koh, Eunmi; Surh, Jeonghee

2016-01-01

Two onions (Sulfur-1 and Sulfur-4) cultivated with different sulfur applications were thermally processed to elucidate the effects of heat treatment on browning index and antioxidant activity. Sulfur-4 onion had higher sulfur content compared with the Sulfur-1 onion. After thermal processing, browning intensity was different between the two onions juices, with lower values observed for Sulfur-4 onion juice. This suggests that sulfur inhibits the Maillard browning reaction. The total reducing capacity of the juices increased at higher thermal processing temperatures; however, it was also lower in the Sulfur-4 onion juice. This suggests that the heat treatment of onions enhanced their antioxidant activity, but the effect was offset in the Sulfur-4 onion juice presumably due to higher sulfur content. This study indicates that sulfur, a core element for the functionality of onions, can decrease the antioxidant activity of thermally processed onions because of its potential as a Maillard reaction inhibitor. PMID:27390734

Quantification of Nε-(2-Furoylmethyl)-L-lysine (furosine), Nε-(Carboxymethyl)-L-lysine (CML), Nε-(Carboxyethyl)-L-lysine (CEL) and total lysine through stable isotope dilution assay and tandem mass spectrometry.

PubMed

Troise, Antonio Dario; Fiore, Alberto; Wiltafsky, Markus; Fogliano, Vincenzo

2015-12-01

The control of Maillard reaction (MR) is a key point to ensure processed foods quality. Due to the presence of a primary amino group on its side chain, lysine is particularly prone to chemical modifications with the formation of Amadori products (AP), Nε-(Carboxymethyl)-L-lysine (CML), Nε-(Carboxyethyl)-L-lysine (CEL). A new analytical strategy was proposed which allowed to simultaneously quantify lysine, CML, CEL and the Nε-(2-Furoylmethyl)-L-lysine (furosine), the indirect marker of AP. The procedure is based on stable isotope dilution assay followed by liquid chromatography tandem mass spectrometry. It showed high sensitivity and good reproducibility and repeatability in different foods. The limit of detection and the RSD% were lower than 5 ppb and below 8%, respectively. Results obtained with the new procedure not only improved the knowledge about the reliability of thermal treatment markers, but also defined new insights in the relationship between Maillard reaction products and their precursors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Identification, synthesis, isolation and characterization of new impurity in metoprolol tartrate tablets.

PubMed

Reddy, R Buchi; More, Kishor R; Gupta, Leena; Jha, Mukesh S; Magar, Laki

2016-01-05

A new unknown impurity was observed in accelerated stability studies of Metoprolol tartrate tablets. This impurity has been identified, synthesized and characterized through different spectral studies and confirmed as an adduct of lactose and Metoprolol formed by Maillard reaction. Copyright © 2015 Elsevier B.V. All rights reserved.

Corn fiber gum and milk protein conjugates with improved emulsion stability

USDA-ARS?s Scientific Manuscript database

Corn fiber gum (CFG), an alkaline hydrogen peroxide extract of the corn kernel milling by-product “corn fiber” was covalently conjugated with Beta-lactoglobulin (Beta-LG) and whey protein isolate (WPI). Covalent coupling of CFG to protein was achieved by dry heating reaction (Maillard-type) of CFG ...

Maillard reaction and enzymatic browning affect the allergenicity of Pru av 1, the major allergen from cherry (Prunus avium).

PubMed

Gruber, Patrick; Vieths, Stefan; Wangorsch, Andrea; Nerkamp, Jörg; Hofmann, Thomas

2004-06-16

The influence of thermal processing and nonenymatic as well as polyphenoloxidase-catalyzed browning reaction on the allergenicity of the major cherry allergen Pru av 1 was investigated. After thermal treatment of the recombinant protein rPru av 1 in the absence or presence of carbohydrates, SDS-PAGE, enzyme allergosorbent tests, and inhibition assays revealed that thermal treatment of rPru av 1 alone did not show any influence on the IgE-binding activity of the protein at least for 30 min, thus correlating well with the refolding of the allergen in buffer solution as demonstrated by CD spectroscopic experiments. Incubation of the protein with starch and maltose also showed no effect on IgE-binding activity, whereas reaction with glucose and ribose and, even more pronounced, with the carbohydrate breakdown products glyceraldehyde and glyoxal induced a strong decrease of the IgE-binding capacity of rPru av 1. In the second part of the study, the effect of polyphenoloxidase-catalyzed oxidation of polyphenols on food allergen activity was investigated. Incubation of rPru av 1 with epicatechin in the presence of tyrosinase led to a drastic decrease in IgE-binding activity of the protein. Variations of the phenolic compound revealed caffeic acid and epicatechin as the most active inhibitors of the IgE-binding activity of rPru av 1, followed by catechin and gallic acid, and, finally, by quercetin and rutin, showing significantly lower activity. On the basis of these data, reactive intermediates formed during thermal carbohydrate degradation as well as during enzymatic polyphenol oxidation are suggested as the active chemical species responsible for modifying nucleophilic amino acid side chains of proteins, thus inducing an irreversible change in the tertiary structure of the protein and resulting in a loss of conformational epitopes of the allergen.

Advances of zeolite based membrane for hydrogen production via water gas shift reaction

NASA Astrophysics Data System (ADS)

Makertihartha, I. G. B. N.; Zunita, M.; Rizki, Z.; Dharmawijaya, P. T.

2017-07-01

Hydrogen is considered as a promising energy vector which can be obtained from various renewable sources. However, an efficient hydrogen production technology is still challenging. One technology to produce hydrogen with very high capacity with low cost is through water gas shift (WGS) reaction. Water gas shift reaction is an equilibrium reaction that produces hydrogen from syngas mixture by the introduction of steam. Conventional WGS reaction employs two or more reactors in series with inter-cooling to maximize conversion for a given volume of catalyst. Membrane reactor as new technology can cope several drawbacks of conventional reactor by removing reaction product and the reaction will favour towards product formation. Zeolite has properties namely high temperature, chemical resistant, and low price makes it suitable for membrane reactor applications. Moreover, it has been employed for years as hydrogen selective layer. This review paper is focusing on the development of membrane reactor for efficient water gas shift reaction to produce high purity hydrogen and carbon dioxide. Development of membrane reactor is discussed further related to its modification towards efficient reaction and separation from WGS reaction mixture. Moreover, zeolite framework suitable for WGS membrane reactor will be discussed more deeply.

Yeast Metabolites of Glycated Amino Acids in Beer.

PubMed

Hellwig, Michael; Beer, Falco; Witte, Sophia; Henle, Thomas

2018-06-01

Glycation reactions (Maillard reactions) during the malting and brewing processes are important for the development of the characteristic color and flavor of beer. Recently, free and protein-bound Maillard reaction products (MRPs) such as pyrraline, formyline, and maltosine were found in beer. Furthermore, these amino acid derivatives are metabolized by Saccharomyces cerevisiae via the Ehrlich pathway. In this study, a method was developed for quantitation of individual Ehrlich intermediates derived from pyrraline, formyline, and maltosine. Following synthesis of the corresponding reference material, the MRP-derived new Ehrlich alcohols pyrralinol (up to 207 μg/L), formylinol (up to 50 μg/L), and maltosinol (up to 6.9 μg/L) were quantitated for the first time in commercial beer samples by reverse phase high performance liquid chromatography tandem mass spectrometry in the multiple reaction monitoring mode. This is equivalent to ca. 20-40% of the concentrations of the parent glycated amino acids. The metabolites were almost absent from alcohol-free beers and malt-based beverages. Two previously unknown valine-derived pyrrole derivatives were characterized and qualitatively identified in beer. The metabolites investigated represent new process-induced alkaloids that may influence brewing yeast performance due to structural similarities to quorum sensing and metal-binding molecules.

Heavy ion fusion reactions in stars

NASA Astrophysics Data System (ADS)

Tang, X. D.

2018-04-01

Heavy ion fusion reactions play important roles in a wide variety of stellar burning scenarios. 12C+12C, 12C+16O and 16O+16O are the principle reactions during the advance burning stages of massive star. 12C+12C also triggers the happening of superburst and Type Ia supernovae. The heavy ion fusion reactions of the neutron-rich isotopes such as 24O are the major heating source in the crust of neutron star. In this talk, I will review the challenges and the recent progress in the study of these heavy ion fusion reactions at stellar energies. The outlook for the studies of the astrophysical heavy-ion fusion reactions will also be presented.

β-Blocker premedication does not increase the frequency of allergic reactions from coronary CT angiography: Results from the Advanced Cardiovascular Imaging Consortium.

PubMed

Aggarwal, Anshul; Smith, James L; Chinnaiyan, Kavitha M; Mehta, Neesurg; Boura, Judith; Khoury Abdulla, Rami; Lauter, Carl B; Raff, Gilbert L

2015-01-01

β-Blockers are often used for heart rate control during coronary CT angiography (CTA). Increased frequency and severity of allergic reactions to radiocontrast media (RCM) have been reported with concomitant use of β-blockers. The objectives of this study were to determine whether there is a higher incidence of allergic reactions to low-osmolar nonionic RCM in patients undergoing coronary CTA with concomitant β-blockers and to define the overall incidence and severity of allergic reactions in patients undergoing coronary CTA with and without a history of allergy to RCM. Patients undergoing coronary CTA at 47 institutions participating in the Advanced Cardiovascular Imaging Consortium registry were analyzed. The incidence and severity of allergic reactions were compared between those patients who did and those who did not receive β-blockers, as well as in subgroups of patients with and without a history of prior allergy to RCM. The incidence of allergic reaction in patients who received β-blockers was 45 of 23,867 (0.19%) compared with those who did not receive β-blockers, which was 9 of 5232 (0.17%; P = .84; odds ratio = 1.1). Of the patients with history of allergy to RCM, 4 of 706 patients (0.6%) on β-blockers experienced allergic reactions compared to 1 of 77 patients (1.3%) without β-blockers (P = .40; odds ratio = 0.43). β-Blocker pretreatment had no effect on the frequency or severity of allergic reaction in patients undergoing coronary CTA, even in patients with a past history of allergy to RCM. Copyright © 2015 Society of Cardiovascular Computed Tomography. Published by Elsevier Inc. All rights reserved.

Acacia gum as modifier of thermal stability, solubility and emulsifying properties of α-lactalbumin.

PubMed

de Oliveira, Fabíola Cristina; Dos Reis Coimbra, Jane Sélia; de Oliveira, Eduardo Basílio; Rodrigues, Marina Quadrio Raposo Branco; Sabioni, Rachel Campos; de Souza, Bartolomeu Warlene Silva; Santos, Igor José Boggione

2015-03-30

Protein-polysaccharide conjugates often display improved techno-functional properties when compared to their individual involved biomolecules. α-Lactalbumin:acacia gum (α-la:AG) conjugates were prepared via Maillard reaction by the dry-heating method. Conjugate formation was confirmed using results of absorbance, o-phthalaldehyde test, sodium dodecyl sulfate-polyacrilamide gel electrophoresis (SDS-PAGE) and size exclusion chromatography. Techno-functional properties (emulsifying characteristics, solubility, and thermal stability) were evaluated for α-la, α-la/AG mixtures and α-la:AG conjugates. Conjugate thermal stability was improved compared to pure α-la treated at the same conditions of conjugate formation. Response surface methodology was used to establish models to predict solubility and emulsifying activity as functions of the salt concentration, pH and reaction time. α-la:AG conjugate solubility is affected in a complex manner by the three factors analyzed. Emulsifying activity index (EAI) of α-la is significantly affected by pH, while the α-la:AG EAI is affected by the three analyzed factors. Both solubility and EAI are maximized with pH 8.0, NaCl concentration of 0.3 mol L(-1) and two days of Maillard reaction. Copyright © 2014 Elsevier Ltd. All rights reserved.

Effect of L-asparaginase on acrylamide mitigation in a fried-dough pastry model.

PubMed

Kukurová, Kristína; Morales, Francisco J; Bednáriková, Alena; Ciesarová, Zuzana

2009-12-01

A dough resembling traditional Spanish rosquillas was used as a model to represent classical fried-dough pastry to investigate the effects of asparaginase and heat treatment on amino acid levels and acrylamide mitigation. Wheat-based dough was deep fried at 180 and 200 degrees C for 4, 6, and 8 min. Two recipes were formulated by addition of different asparaginase levels (100 and 500 U/kg flour) to the dough. The temperature/time profile of the frying process, moisture, sugars, amino acids, acrylamide, and some indicators of the Maillard reaction (hydroxymethylfurfural, color, free fluorescence compounds, and browning) were determined to investigate the extent of the reaction and the effect on reactants. At the both levels of asparaginase used, 96-97% of the asparagine present was converted to aspartic acid, and consequently the acrylamide level was very efficiently reduced (up to 90%). The asparaginase also affected the content of glutamine and glutamic acid in dough, resulting in a 37% increase in glutamic acid compared with the untreated sample. Concerning color, browning and Maillard reaction parameters, no significant changes between untreated and enzymatically treated samples were observed, pointing out the potential industrial and domestic enzyme application.

Use of a Passive Reaction Wheel Jitter Isolation System to Meet the Advanced X-Ray Astrophysics Facility Imaging Performance Requirements

NASA Technical Reports Server (NTRS)

Pendergast, Karl J.; Schauwecker, Christopher J.

1998-01-01

Third in the series of NASA great observatories, the Advanced X-Ray Astrophysics Facility (AXAF) is scheduled for launch from the Space Shuttle in November of 1998. Following in the path of the Hubble Space Telescope and the Compton Gamma Ray Observatory, this observatory will image light at X-ray wavelengths, facilitating the detailed study of such phenomena as supernovae and quasars. The AXAF project is sponsored by the Marshall Space Flight Center in Huntsville, Alabama. Because of exacting requirements on the performance of the AXAF optical system, it was necessary to reduce the transmission of reaction wheel jitter disturbances to the observatory. This reduction was accomplished via use of a passive mechanical isolation system to interface the reaction wheels with the spacecraft central structure. In addition to presenting a description of the spacecraft, the isolation system, and the key image quality requirement flowdown, this paper details the analyses performed in support of system-level imaging performance requirement verification. These analyses include the identification of system-level requirement suballocations, quantification of imaging and pointing performance, and formulation of unit-level isolation system transmissibility requirements. Given in comparison to the non-isolated system imaging performance, the results of these analyses clearly illustrate the effectiveness of an innovative reaction wheel passive isolation system.

Anti-glycation activities of phenolic constituents from Silybum marianum (Milk Thistle) flower in vitro and on human explants.

PubMed

Shin, Seoungwoo; Lee, Jung-A; Kim, Minkyung; Kum, Hyunwoo; Jung, Eunsun; Park, Deokhoon

2015-02-19

Glycation is an ageing reaction of naturally occurring sugars with dermal proteins, with clinical signs appearing in vivo around age 30, and increasing steadily/regularly with age. The suppleness of the dermis is affected by the formation of bridges between proteins and sugars (Maillard's reaction). The accumulation of advanced glycation end products (AGEs) in skin plays a very important role in skin ageing. Therefore, natural compounds or extracts that possess antiglycation activities may have great anti-ageing potential. In the present study, Silybum marianum flower extract (SMFE) was demonstrated to possess antiglycation activity. We found that SMFE inhibits glycation reaction between BSA and glucose. In addition, antiglycation activity of SMFE was confirmed in a human skin explants model. SMFE reduced Nε-(carboxymethyl) lysine (CML) expression, whereas SMFE stimulated fibrillin-1 expression compared to treatment with methyglyoxal. An active ingredient contributing to the observed activities was identified as silibinin. The antiglycation activity of silibinin was dose-dependent. The beneficial effects of silibinin may be applied to prevention or management of AGE-mediated pathologies, targeting in a pleiotropic and complementary way the biochemical and cellular bases of skin aging.

Advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects in 2009.

PubMed

Sicherer, Scott H; Leung, Donald Y M

2010-01-01

This review highlights some of the research advances in anaphylaxis and hypersensitivity reactions to foods, drugs, and insects, as well as advances in allergic skin disease that were reported in the Journal in 2009. Among key epidemiologic observations, several westernized countries report that more than 1% of children have peanut allergy, and there is some evidence that environmental exposure to peanut is a risk factor. The role of regulatory T cells, complement, platelet-activating factor, and effector cells in the development and expression of food allergy were explored in several murine models and human studies. Delayed anaphylaxis to mammalian meats appears to be related to IgE binding to the carbohydrate moiety galactose-alpha-1,3-galactose, which also has implications for hypersensitivity to murine mAb therapeutics containing this oligosaccharide. Oral immunotherapy studies continue to show promise for the treatment of food allergy, but determining whether the treatment causes tolerance (cure) or temporary desensitization remains to be explored. Increased baseline serum tryptase levels might inform the risk of venom anaphylaxis and might indicate a risk for mast cell disorders in persons who have experienced such episodes. Reduced structural and immune barrier function contribute to local and systemic allergen sensitization in patients with atopic dermatitis, as well as increased propensity of skin infections in these patients. The use of increased doses of nonsedating antihistamines and potential usefulness of omalizumab for chronic urticaria was highlighted. These exciting advances reported in the Journal can improve patient care today and provide insights on how we can improve the diagnosis and treatment of these allergic diseases in the future. Copyright 2010 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

[Experiences with the enzymatic determination of sugar and sugar substitutes in dietetic cake for diabetics (author's transl)].

PubMed

Klingebiel, L; Grossklaus, R; Pahlke, G

1979-11-01

Sorbitol and fructose were determined enzymatically in home-made and commercially produced cake for diabetics. In some commercial products, a loss of fructose depending upon the baking period was found. This loss of fructose is to be attributed to the Maillard reaction. The findings were confirmed by comparative studies will a reference cake.

Robust SERS Enhancement Factor Statistics Using Rotational Correlation Spectroscopy

DTIC Science & Technology

2012-05-02

Polymer coatings quench the reaction , preventing further aggregation when a Raman active molecule is added. (B) The bulk Raman spectrum of MBA in...Schrof, W. J. Phys. Chem. A 2001, 105, 3673. (12) Jiang, J.; Bosnick, K.; Maillard , M.; Brus, L. J. Phys. Chem. B 2003, 107, 9964. (13) Talley, C. E

Analysis of the reaction products from micro-vial pyrolysis of the mixture glucose/proline and of a tobacco leaf extract:Search for Amadori intermediates.

PubMed

Mitsui, Kazuhisa; David, Frank; Tienpont, Bart; Sandra, Koen; Ochiai, Nobuo; Tamura, Hirotoshi; Sandra, Pat

2015-11-27

Micro-vial pyrolysis (PyroVial) was used to study the production of compounds important for the aroma of heat-treated natural products such as tobacco. Firstly, a mixture of glucose and proline was pyrolyzed as model, as this sugar and amino acid are also abundant in tobacco leaf (Nicotiana tobacum L.). The pyrolysate was analyzed using headspace-GC–MS, liquid injection GC–MS and LC–MS. Next, micro-vial pyrolysis in combination with LC–MS was applied to tobacco leaf extract. Using MS deconvolution, molecular feature extraction and differential analysis it was possible to identify Amadori intermediates of the Maillard reaction in the tobacco leaf extract. The intermediate disappeared as was the case for 1-deoxy-1-prolino-β-d-fructose or the concentration decreased in the pyrolysate compared to the original extract such as for the 1-deoxy-1-[2-(3-pyridyl)-1-pyrrolidinyl]-β-d-fructose isomers indicating that Amadori intermediates are important precursors for aroma compound formation.

Why Are Some Reactions Slower at Higher Temperatures?

ERIC Educational Resources Information Center

Revell, Laura E.; Williamson, Bryce E.

2013-01-01

It is well understood by most chemistry students at advanced undergraduate levels that chemical reactions generally follow the Arrhenius law of temperature dependence with positive activation energies, proceeding faster at elevated temperatures. It is much less widely known that the rates of some Arrhenius-compliant reactions are retarded by…

Dietary bread crust advanced glycation end products bind to the receptor for AGEs in HEK-293 kidney cells but are rapidly excreted after oral administration to healthy and subtotally nephrectomized rats.

PubMed

Somoza, Veronika; Lindenmeier, Michael; Hofmann, Thomas; Frank, Oliver; Erbersdobler, Helmut F; Baynes, John W; Thorpe, Suzanne R; Heidland, August; Zill, Holger; Bek, Stephan; Huber, Jochen; Weigle, Thomas; Scheidler, Sabine; Busch, Andreas E; Sebeková, Katarína

2005-06-01

In renal HEK-293 cells, the dietary Maillard reaction compounds casein-linked Nepsilon-carboxymethyllysine (CML), CML, bread crust (BC), and pronyl-glycine (a key compound formed in association with the process-induced heat impact applied to bread dough) all showed activation of p38-MAP kinase. Expression of the C-terminus truncated receptor for advanced glycation end products (RAGE) resulted in a reduction of HEK-293-MAP kinase activation. As these findings suggested a RAGE-mediated activating effect of CML, BC, and pronyl-glycine on kidney cellular signal transduction pathways, an in vivo study was performed. Male Wistar rats were subjected to a sham operation (CTRL, n = 20) or to 5/6 nephrectomy (NX, n = 20). Both groups were randomized into two subgroups and fed 20 g of a diet containing either 25% by weight BC or wheat starch (WS). GC-MS analyses of CML, carboxyethyllysine (CEL), and pentosidine revealed increased levels of CML and CEL in the liver but decreased levels of CML in the kidneys of CTRL and NX rats fed the BC diet compared to those on the WS diet. However, urinary levels of CML were also elevated in the CTRL and NX rats on the BC diet, pointing to enhanced excretion of AGEs after BC administration. Although renal insufficiency in the NX rats was reflected by proteinuria, the renal handling of CML and, presumably, other AGEs was not impaired.

The antioxidative effect of bread crust in a mouse macrophage reporter cell line.

PubMed

Pötzsch, Sandy; Dalgalarrondo, Michele; Bakan, Benedicte; Marion, Didier; Somoza, Veronika; Stangl, Gabriele; Silber, Rolf-Edgar; Simm, Andreas; Navarrete Santos, Alexander

2014-10-01

Free radicals and oxidative stress are important factors in the biology of aging and responsible for the development of age-related diseases. One way to reduce the formation of free radicals is to boost the antioxidative system by nutrition. Heat treatment of food promote the Maillard reaction which is responsible for their characteristic color and taste. During the Maillard reaction reducing sugars react with proteins in a non-enzymatic way leading to the formation of advanced glycation end products (AGEs). As an AGE-rich source our group used bread crust (BCE) to investigate the effect of AGEs on the antioxidant defense. It is well known that the NF-kB pathway is activated by treatment of cells with AGEs. Therefore for stimulation with the BCE we used the macrophage reporter cell line RAW/NF-kB/SEAPorter™. Amino acid analysis and LC-MS/MS by Orbitrap Velo was used to determine the bioactive compounds in the soluble BCE. The radical scavenging effect was conducted by the DPPH-assay. BCE induced the NF-kB pathway in RAW/NF-kB/SEAPorter™ cells and also showed a concentration-dependent antioxidative capacity by the DPPH-assay. With the LC/MS and amino acid analyses, we identified the presence of gliadin in BCE confirmed by using specific gliadin antibodies. By immunoprecipitation (IP) with an antibody against γ-gliadin and western blot probing against the AGE carboxymethyllysine (CML) the presence of AGE-gliadin in BCE was confirmed. Stimulation of the RAW/NF-kB/SEAPorter™ cells with the γ-gliadin depleted fractions did not activate the NF-kB pathway. CML-modified gliadin in the BCE is a bioactive compound of the bread crust which is responsible for the antioxidative capacity and for the induction of the NF-kB pathway in mouse macrophages. Copyright © 2014. Published by Elsevier Inc.

Extending the spectrum of α-dicarbonyl compounds in vivo.

PubMed

Henning, Christian; Liehr, Kristin; Girndt, Matthias; Ulrich, Christof; Glomb, Marcus A

2014-10-10

Maillard α-dicarbonyl compounds are known as central intermediates in advanced glycation end product (AGE) formation. Glucose is the primary source of energy for the human body, whereas l-threo-ascorbic acid (vitamin C) is an essential nutrient, involved in a variety of enzymatic reactions. Thus, the Maillard degradation of glucose and ascorbic acid is of major importance in vivo. To understand the complex mechanistic pathways of AGE formation, it is crucial to extend the knowledge on plasma concentrations of reactive key α-dicarbonyl compounds (e.g. 1-deoxyglucosone). With the present work, we introduce a highly sensitive LC-MS/MS multimethod for human blood plasma based on derivatization with o-phenylenediamine under acidic conditions. The impact of workup and reaction conditions, particularly of pH, was thoroughly evaluated. A comprehensive validation provided the limit of detection, limit of quantitation, coefficients of variation, and recovery rates. The method includes the α-dicarbonyls 1-deoxyglucosone, 3-deoxyglucosone, glucosone, Lederer's glucosone, dehydroascorbic acid, 2,3-diketogulonic acid, 1-deoxypentosone, 3-deoxypentosone, 3,4-dideoxypentosone, pentosone, 1-deoxythreosone, 3-deoxythreosone, threosone, methylglyoxal, glyoxal; the α-keto-carboxylic acids pyruvic acid and glyoxylic acid; and the dicarboxylic acid oxalic acid. The method was then applied to the analyses of 15 healthy subjects and 24 uremic patients undergoing hemodialysis. The comparison of the results revealed a clear shift in the product spectrum. In most cases, the plasma levels of target analytes were significantly higher. Thus, this is the first time that a complete spectrum of α-dicarbonyl compounds relevant in vivo has been established. The results provide further insights into the chemistry of AGE formation and will be helpful to find specific markers to differentiate between the various precursors of glycation. © 2014 by The American Society for Biochemistry and

Recent advances in transition metal-catalyzed N -atom transfer reactions of azides

PubMed Central

Driver, Tom G.

2011-01-01

Transition metal-catalyzed N-atom transfer reactions of azides provide efficient ways to construct new carbon–nitrogen and sulfur–nitrogen bonds. These reactions are inherently green: no additive besides catalyst is needed to form the nitrenoid reactive intermediate, and the by-product of the reaction is environmentally benign N2 gas. As such, azides can be useful precursors for transition metal-catalyzed N-atom transfer to sulfides, olefins and C–H bonds. These methods offer competitive selectivities and comparable substrate scope as alternative processes to generate metal nitrenoids. PMID:20617243

Antimicrobial Mechanism of Action of Surfactant Lipid Preparations in Enteric Gram-Negative Bacilli

DTIC Science & Technology

2001-12-25

The addition of EDTA/Tris to the reaction the bacterial cells in the assay time (15min). W60C (1%) mixture results in chelation of ions, facilitating... Maillard , J.Y. (1999) Do antisep- Hamouda, T., Hayes, M.M., Cao, Z. et al. (1999) A novel surfac- tics and disinfectants select for antibiotic resistance

Formation of Sphere-like Au Nanoparticles on Substrate with Laser Illumination and Their Surface Plasmon Behaviors

DTIC Science & Technology

2010-09-17

depends on the material type of the substrate and the metal melting temperature. Based on the reaction -free theory, the contact angle of an Au...Luo, Q.; Zhang, X. Nano Lett. 2004, 4, 1085-1088. (13) Maillard , M.; Huang, P.; Brus, L. Nano Lett. 2003, 3, 1611-1615. (14) Jin, R.; Cao, Y. C.; Hao

A One-Pot Synthesis of m-Terphenyls: A Guided Exploration of Reaction Chemistry, Chromatography, and Spectroscopy. A Miniproject for the Advanced Organic Chemistry Laboratory

NASA Astrophysics Data System (ADS)

Anam, Kishorekumar T.; Curtis, Michael P.; Irfan, Muhammad J.; Johnson, Michael P.; Royer, Andrew P.; Shahmohammadi, Kianor; Vinod, Thottumkara K.

2002-05-01

This four-week project-based laboratory exercise, developed for advanced organic chemistry students, involves a one-pot synthesis of m-terphenyls. Chemistry of aryl diazonium salts and Grignard reagents and reactivity of aryne intermediates toward nucleophilic reagents form the reaction chemistry basis for the project. The project exposes students to a number of important laboratory techniques (thin-layer chromatography, gas chromatography-mass spectrometry, and column chromatography) for monitoring reaction progress and product isolation. A variety of spectroscopic techniques, including IR, 1H NMR, 13C NMR, and attached proton test are used for product characterization. Students are also introduced to a useful empirical relationship to help predict (with considerable accuracy) the 13C chemical shift values of carbon atoms of substituted benzenes.

Odour characteristics of seafood flavour formulations produced with fish by-products incorporating EPA, DHA and fish oil.

PubMed

Peinado, I; Miles, W; Koutsidis, G

2016-12-01

Thermal degradation of eicosapentaenoic (EPA) and docosahexaenoic (DHA) acids was investigated. As a novelty, EPA, DHA or fish oil (FO) were incorporated as ω-fatty acid sources into model systems containing fish powder produced via Maillard reactions. Aroma composition of the resulting products was determined and complemented with sensory evaluation. Heating of the oils led to a fast decrease of both, EPA and DHA, and to the development of characteristic volatile compounds including hexanal, 2,4-heptadienal and 4-heptenal, the most abundant being (E,E)-2,4-heptadienal (132±44-329±122μmol/g). EPA and DHA addition to the model systems increased the concentration of these characteristic volatile compounds. However, it did not have a considerable impact on the development of characteristic Maillard reaction products, such as pyrazines and some aldehydes. Finally, the results of the sensory evaluation illustrated that panellists would chose samples fortified with FO as the ones with a more pleasant aroma. Copyright © 2016 Elsevier Ltd. All rights reserved.

Advanced glycation end products, physico-chemical and sensory characteristics of cooked lamb loins affected by cooking method and addition of flavour precursors.

PubMed

Roldan, Mar; Loebner, Jürgen; Degen, Julia; Henle, Thomas; Antequera, Teresa; Ruiz-Carrascal, Jorge

2015-02-01

The influence of the addition of a flavour enhancer solution (FES) (d-glucose, d-ribose, l-cysteine and thiamin) and of sous-vide cooking or roasting on moisture, cooking loss, instrumental colour, sensory characteristics and formation of Maillard reaction (MR) compounds in lamb loins was studied. FES reduced cooking loss and increased water content in sous-vide samples. FES and cooking method showed a marked effect on browning development, both on the meat surface and within. FES led to tougher and chewier texture in sous-vide cooked lamb, and enhanced flavour scores of sous-vide samples more markedly than in roasted ones. FES added meat showed higher contents of furosine; 1,2-dicarbonyl compounds and 5-hydroxymethylfurfural did not reach detectable levels. N-ε-carboxymethyllysine amounts were rather low and not influenced by the studied factors. Cooked meat seems to be a minor dietary source of MR products, regardless the presence of reducing sugars and the cooking method. Copyright © 2014 Elsevier Ltd. All rights reserved.

Calcium-Magnesium-Alumino-Silicates (CMAS) Reaction Mechanisms and Resistance of Advanced Turbine Environmental Barrier Coatings for SiC/SiC Ceramic Matrix Composites

NASA Technical Reports Server (NTRS)

Zhu, Dongming; Costa, Gustavo; Harder, Bryan J.; Wiesner, Valerie L.; Hurst, Janet B.; Puleo, Bernadette J.

2017-01-01

Environmental barrier coatings (EBCs) and SiC/SiC ceramic matrix composites (CMCs) systems will play a crucial role in future turbine engines for hot-section component applications because of their ability to significantly increase engine operating temperatures, reduce engine weight and cooling requirements. The development of prime-reliant environmental barrier coatings is an essential requirement to enable the applications of the 2700-3000 F EBC - CMC systems. This presentation primarily focuses on the reaction mechanisms of advanced NASA environmental barrier coating systems, when in contact with Calcium-Magnesium Alumino-Silicates (CMAS) at high temperatures. Advanced oxide-silicate defect cluster environmental barrier coatings are being designed for ultimate balanced controls of the EBC temperature capability and CMAS reactivity, thus improving the CMAS resistance. Further CMAS mitigation strategies are also discussed.

Amides are novel protein modifications formed by physiological sugars.

PubMed

Glomb, M A; Pfahler, C

2001-11-09

The Maillard reaction, or nonenzymatic browning, proceeds in vivo, and the resulting protein modifications (advanced glycation end products) have been associated with various pathologies. Despite intensive research only very few structures have been established in vivo. We report here for the first time N(6)-[2-[(5-amino-5-carboxypentyl)amino]-2-oxoethyl]lysine (GOLA) and N(6)-glycoloyllysine (GALA) as prototypes for novel amide protein modifications produced by reducing sugars. Their identity was confirmed by independent synthesis and coupled liquid chromatography/mass spectrometry. Model reactions with N(alpha)-t-butoxycarbonyl-lysine showed that glyoxal and glycolaldehyde are immediate precursors, and reaction pathways are directly linked to N(epsilon)-carboxymethyllysine via glyoxal-imine structures. GOLA, the amide cross-link, and 1,3-bis(5-amino-5-carboxypentyl)imidazolium salt (GOLD), the imidazolium cross-link, share a common intermediate. The ratio of GOLA to GOLD is greater when glyoxal levels are low at constant lysine concentrations. GOLA and GALA formation from the Amadori product of glucose and lysine depends directly upon oxidation. With the advanced glycation end product inhibitors aminoguanidine and pyridoxamine we were able to dissect oxidative fragmentation of the Amadori product as a second mechanism of GOLA formation exactly coinciding with N(epsilon)-carboxymethyllysine synthesis. In contrast, the formation of GALA appears to depend solely upon glyoxal-imines. After enzymatic hydrolysis GOLA was found at 66 pmol/mg of brunescent lens protein. This suggests amide protein modifications as important markers of pathophysiological processes.

Enzymatic reactions in confined environments

NASA Astrophysics Data System (ADS)

Küchler, Andreas; Yoshimoto, Makoto; Luginbühl, Sandra; Mavelli, Fabio; Walde, Peter

2016-05-01

Within each biological cell, surface- and volume-confined enzymes control a highly complex network of chemical reactions. These reactions are efficient, timely, and spatially defined. Efforts to transfer such appealing features to in vitro systems have led to several successful examples of chemical reactions catalysed by isolated and immobilized enzymes. In most cases, these enzymes are either bound or adsorbed to an insoluble support, physically trapped in a macromolecular network, or encapsulated within compartments. Advanced applications of enzymatic cascade reactions with immobilized enzymes include enzymatic fuel cells and enzymatic nanoreactors, both for in vitro and possible in vivo applications. In this Review, we discuss some of the general principles of enzymatic reactions confined on surfaces, at interfaces, and inside small volumes. We also highlight the similarities and differences between the in vivo and in vitro cases and attempt to critically evaluate some of the necessary future steps to improve our fundamental understanding of these systems.

Rule-Based Event Processing and Reaction Rules

NASA Astrophysics Data System (ADS)

Paschke, Adrian; Kozlenkov, Alexander

Reaction rules and event processing technologies play a key role in making business and IT / Internet infrastructures more agile and active. While event processing is concerned with detecting events from large event clouds or streams in almost real-time, reaction rules are concerned with the invocation of actions in response to events and actionable situations. They state the conditions under which actions must be taken. In the last decades various reaction rule and event processing approaches have been developed, which for the most part have been advanced separately. In this paper we survey reaction rule approaches and rule-based event processing systems and languages.

Recent advances in heterocycle generation using the efficient Ugi multiple-component condensation reaction.

PubMed

Tempest, Paul A

2005-11-01

The current trend of rising research spending and falling numbers of novel chemical entities continues to drive efforts aimed at increasing efficiency in the drug discovery process. Strategic issues, such as assigning resources to poorly validated targets have been implicated in the declining productivity of recent years. Tactical approaches employed to improve this situation include attempts to speed the discovery process toward decision points in a timely manner. Accelerating the optimization of high-throughput screening hits is a goal in streamlining the discovery process, and the use of multiple-component condensation (MCC) reactions have proved useful toward this end. MCC reactions are powerful and efficient tools for the generation of diverse compound sets. Collections of compounds can be synthesized with all of the required diversity elements included in a single synthetic step. One of the most widely investigated MCC reactions is the Ugi four-component condensation. This review highlights disclosures of the Ugi reaction published over the past two years (2003 to 2005) in three areas: (i) Ugi reaction in conjunction with post-condensation cyclization; (ii) bifunctional condensations leading to heterocyclic cores; and (iii) general findings relating to linear products or interesting improvements in the basic Ugi reaction.

Hydroxyurea-Lactose Interaction Study: In Silico and In Vitro Evaluation.

PubMed

Bachchhao, Kunal B; Patil, R R; Patil, C R; Patil, Dipak D

2017-11-01

The Maillard reaction between hydroxyurea (a primary amine-containing drug) and lactose (used as an excipient) was explored. The adduct of these compounds was synthesized by heating hydroxyurea with lactose monohydrate at 60 °C in borate buffer (pH 9.2) for 12 h. Synthesis of the adduct was confirmed using UV-visible spectroscopy and Fourier transform infrared, differential scanning calorimetry, high-pressure liquid chromatography, and liquid chromatography-mass spectrometry studies. An in silico investigation of how the adduct formation affected the interactions of hydroxyurea with its biological target oxyhemoglobin, to which it binds to generate nitric oxide and regulates fetal hemoglobin synthesis, was carried out. The in silico evaluations were complemented by an in vitro assay of the anti-sickling activity. Co-incubation of hydroxyurea with deoxygenated blood samples reduced the percentage of sickled cells from 38% to 12 ± 1.6%, whereas the percentage of sickled cells in samples treated with the adduct was 17 ± 1.2%. This indicated loss of anti-sickling activity in the case of the adduct. This study confirmed that hydroxyurea can participate in a Maillard reaction if lactose is used as a diluent. Although an extended study at environmentally feasible temperatures was not carried out in the present investigation, the partial loss of the anti-sickling activity of hydroxyurea was investigated along with the in silico drug-target interactions. The results indicated that the use of lactose in hydroxyurea formulations needs urgent reconsideration and that lactose must be replaced by other diluents that do not form Maillard adducts.

Molecular Beam Studies of Hot Atom Chemical Reactions: Reactive Scattering of Energetic Deuterium Atoms

DOE R&D Accomplishments Database

Continetti, R. E.; Balko, B. A.; Lee, Y. T.

1989-02-01

A brief review of the application of the crossed molecular beams technique to the study of hot atom chemical reactions in the last twenty years is given. Specific emphasis is placed on recent advances in the use of photolytically produced energetic deuterium atoms in the study of the fundamental elementary reactions D + H{sub 2} -> DH + H and the substitution reaction D + C{sub 2}H{sub 2} -> C{sub 2}HD + H. Recent advances in uv laser and pulsed molecular beam techniques have made the detailed study of hydrogen atom reactions under single collision conditions possible.

Risk Factors for Oxaliplatin-Induced Hypersensitivity Reactions in Japanese Patients with Advanced Colorectal Cancer

PubMed Central

Seki, Kyoko; Senzaki, Kenzou; Tsuduki, Yasuo; Ioroi, Takeshi; Fujii, Michiko; Yamauchi, Hiroko; Shiraishi, Yukinari; Nakata, Izumi; Nishiguchi, Kohshi; Matsubayashi, Teruhisa; Takakubo, Yoshihide; Okamura, Noboru; Yamamori, Motohiro; Tamura, Takao; Sakaeda, Toshiyuki

2011-01-01

Objective: Previously, we suggested that oxaliplatin (L-OHP)-related grade 3/4 hypersensitivity reactions occurred immediately after the initiation, but grade 1/2 reactions did not. This study was conducted to clarify the risk factors for L-OHP-related hypersensitivity reactions. Methods: Clinical data from 108 Japanese patients with colorectal cancer were analyzed, who were treated with L-OHP-containing regimens, FOLFOX4 and/or mFOLFOX6. The risk factors examined included demographic data, preexisting allergies, laboratory test data, treatment regimen, treatment line of therapy, pretreatment with steroids, total number of cycles and cumulative amount of L-OHP. Results: The incidence of grade 1/2 and grade 3/4 hypersensitivity reactions were found at 13.0% (14/108) and 9.3% (10/108), respectively. Female (P=0.037), preexisting allergies (P=0.004) and lower level of lactate dehydrogenase (P=0.003) were risk factors for grade 1/2 hypersensitivity reactions, and higher neutrophil count (P=0.043) and lower monocyte count (P=0.007) were for grade 3/4 reactions. Total number of cycles were larger in the patients with grade 3/4 reactions than those without reactions (P=0.049). Conclusions: Further extensive examination with a large number of patients is needed to establish a patient management strategy. PMID:21448307

Rational Design of Na(Li1/3 Mn2/3 )O2 Operated by Anionic Redox Reactions for Advanced Sodium-Ion Batteries.

PubMed

Kim, Duho; Cho, Maenghyo; Cho, Kyeongjae

2017-09-01

In an effort to develop high-energy-density cathodes for sodium-ion batteries (SIBs), low-cost, high capacity Na(Li 1/3 Mn 2/3 )O 2 is discovered, which utilizes the labile O 2p-electron for charge compensation during the intercalation process, inspired by Li 2 MnO 3 redox reactions. Na(Li 1/3 Mn 2/3 )O 2 is systematically designed by first-principles calculations considering the Li/Na mixing enthalpy based on the site preference of Na in the Li sites of Li 2 MnO 3 . Using the anionic redox reaction (O 2- /O - ), this Mn-oxide is predicted to show high redox potentials (≈4.2 V vs Na/Na + ) with high charge capacity (190 mAh g -1 ). Predicted cathode performance is validated by experimental synthesis, characterization, and cyclic performance studies. Through a fundamental understanding of the redox reaction mechanism in Li 2 MnO 3 , Na(Li 1/3 Mn 2/3 )O 2 is designed as an example of a new class of promising cathode materials, Na(Li 1/3 M 2/3 )O 2 (M: transition metals featuring stabilized M 4+ ), for further advances in SIBs. © 2017 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Behaviour of non-oxidized and oxidized flaxseed oils, as models of omega-3 rich lipids, during in vitro digestion. Occurrence of epoxidation reactions.

PubMed

Nieva-Echevarría, Bárbara; Goicoechea, Encarnación; Guillén, María D

2017-07-01

Fresh and partially oxidized flaxseed oil, as models of omega-3 rich lipids, were submitted to in vitro gastrointestinal digestion. Hydrolysis level, lipid composition and oxidative status of the samples before and after digestion were studied by Proton Nuclear Magnetic Resonance ( 1 H NMR) and Solid Phase Microextraction-Gas Chromatography/Mass Spectrometry (SPME-GC/MS). Although a great degree of lipolysis was reached in both kinds of samples after digestion, it was somewhat lower in the digests of oxidized flaxseed oil. The occurrence of lipid oxidation during digestion was evidenced by decreased unsaturated lipids and increased primary and secondary oxidation products, especially in oxidized samples. In these latter, linolenic-derived monoepoxy-octadecadienoates were the main oxidation products generated. SPME-GC/MS study showed the highest abundances of highly reactive alkadienals (C5-C10), alkatrienals (C9-C10) and linolenic-derived 4,5-epoxy-2-heptenals in the headspace of oxidized flaxseed oil digests. Volatile markers of Maillard-type reactions were also detected. Copyright © 2017 Elsevier Ltd. All rights reserved.

NMR reaction monitoring in flow synthesis.

PubMed

Gomez, M Victoria; de la Hoz, Antonio

2017-01-01

Recent advances in the use of flow chemistry with in-line and on-line analysis by NMR are presented. The use of macro- and microreactors, coupled with standard and custom made NMR probes involving microcoils, incorporated into high resolution and benchtop NMR instruments is reviewed. Some recent selected applications have been collected, including synthetic applications, the determination of the kinetic and thermodynamic parameters and reaction optimization, even in single experiments and on the μL scale. Finally, software that allows automatic reaction monitoring and optimization is discussed.

NMR reaction monitoring in flow synthesis

PubMed Central

Gomez, M Victoria

2017-01-01

Recent advances in the use of flow chemistry with in-line and on-line analysis by NMR are presented. The use of macro- and microreactors, coupled with standard and custom made NMR probes involving microcoils, incorporated into high resolution and benchtop NMR instruments is reviewed. Some recent selected applications have been collected, including synthetic applications, the determination of the kinetic and thermodynamic parameters and reaction optimization, even in single experiments and on the μL scale. Finally, software that allows automatic reaction monitoring and optimization is discussed. PMID:28326137

Recent advances in the chemistry of Rh carbenoids: multicomponent reactions of diazocarbonyl compounds

NASA Astrophysics Data System (ADS)

Medvedev, J. J.; Nikolaev, V. A.

2015-07-01

Multicomponent reactions of diazo compounds catalyzed by RhII complexes become a powerful tool for organic synthesis. They enable three- or four-step processes to be carried out as one-pot procedures (actually as one step) with high stereoselectivity to give complex organic molecules, including biologically active compounds. This review addresses recent results in the chemistry of Rh-catalyzed multicomponent reactions of diazocarbonyl compounds with the intermediate formation of N-, O- and C=O-ylides. The diastereo- and enantioselectivity of these reactions and the possibility of using various co-catalysts to increase the efficiency of the processes under consideration are discussed. The bibliography includes 120 references.

Analysis of amino acids and carbohydrates in green coffee.

PubMed

Murkovic, Michael; Derler, Karin

2006-11-30

The analysis of carbohydrates and amino acids in green coffee is of the utmost importance since these two classes of compounds act as precursors of the Maillard reaction during which the colour and aroma are formed. During the course of the Maillard reaction potentially harmful substances like acrylamide or 5-hydroxymethyl-furfural accrue as well. The carbohydrates were analysed by anion-exchange chromatography with pulsed amperometric detection and the amino acids by reversed phase chromatography after derivatization with 6-amino-quinolyl-N-hydroxysuccinimidyl carbamate and fluorescence detection. Both methods had to be optimized to obtain a sufficient resolution of the analytes for identification and quantification. Sucrose is the dominant carbohydrate in green coffee with a concentration of up to 90 mg/g (mean = 73 mg/g) in arabica beans and significantly lower amounts in robusta beans (mean=45 mg/g). Alanine is the amino acid with the highest concentration (mean = 1200 microg/g) followed by asparagine (mean = 680 microg/g) in robusta and 800 microg/g and 360 microg/g in arabica respectively. In general, the concentration of amino acids is higher in robusta than in arabica.

Cation or Solvent-Induced Supermolecular Phthalocyanine Formation: Crown Ether Substituted Phthalocyanines.

DTIC Science & Technology

1987-06-01

38.) of slightly bluish green powder (Anal, see Table I). tH NMR(CDCl 3 ) 8.02(8H,s), 4.7-3.6(64H,m), - 3.41(2H,s). ZnCRPc was obtained by reaction of...J.P.; Bencosme, S.; Evitt, E., Sessler, J. Chem. Phys. 1984, 86, 161. Mialoco, C.; Giannotti, A., Maillard , P.; Momeuteau, M. Chem. Phys. Lett. 1984

Reaction Mechanisms on Multiwell Potential Energy Surfaces in Combustion (and Atmospheric) Chemistry

DOE PAGES

Osborn, David L.

2017-03-15

Chemical reactions occurring on a potential energy surface with multiple wells are ubiquitous in low temperature combustion and the oxidation of volatile organic compounds in earth’s atmosphere. The rich variety of structural isomerizations that compete with collisional stabilization make characterizing such complex-forming reactions challenging. This review describes recent experimental and theoretical advances that deliver increasingly complete views of their reaction mechanisms. New methods for creating reactive intermediates coupled with multiplexed measurements provide many experimental observables simultaneously. Automated methods to explore potential energy surfaces can uncover hidden reactive pathways, while master equation methods enable a holistic treatment of both sequential andmore » well-skipping pathways. Our ability to probe and understand nonequilibrium effects and reaction sequences is increasing. These advances provide the fundamental science base for predictive models of combustion and the atmosphere that are crucial to address global challenges.« less

Reaction Mechanisms on Multiwell Potential Energy Surfaces in Combustion (and Atmospheric) Chemistry

DOE Office of Scientific and Technical Information (OSTI.GOV)

Osborn, David L.

Chemical reactions occurring on a potential energy surface with multiple wells are ubiquitous in low temperature combustion and the oxidation of volatile organic compounds in earth’s atmosphere. The rich variety of structural isomerizations that compete with collisional stabilization make characterizing such complex-forming reactions challenging. This review describes recent experimental and theoretical advances that deliver increasingly complete views of their reaction mechanisms. New methods for creating reactive intermediates coupled with multiplexed measurements provide many experimental observables simultaneously. Automated methods to explore potential energy surfaces can uncover hidden reactive pathways, while master equation methods enable a holistic treatment of both sequential andmore » well-skipping pathways. Our ability to probe and understand nonequilibrium effects and reaction sequences is increasing. These advances provide the fundamental science base for predictive models of combustion and the atmosphere that are crucial to address global challenges.« less

Nuclear reaction rate uncertainties and the 22Ne( p,gamma)23Na reaction: Classical novae and globular clusters

NASA Astrophysics Data System (ADS)

Kelly, Keegan John

The overall theme of this thesis is the advancement of nuclear astrophysics via the analysis of stellar processes in the presence of varying levels of precision in the available nuclear data. With regard to classical novae, the level of mixing that occurs between the outer layers of the white dwarf core and the solar accreted material in oxygen-neon novae is presently undetermined by stellar models, but the nuclear data relevant to these explosive phenomena are fairly precise. This precision allowed for the identification of a series of elemental ratios indicative of the level of mixing occurring in novae. Direct comparisons of the modelled elemental ratios to observations showed that there is likely to be much less of this mixing than was previously assumed. Thus, our understanding of classical novae was altered via the investigation of the nuclear reactions relevant to this phenomenon. However, this level of experimental precision is rare and large nuclear reaction uncertainties can hinder our understanding of certain astrophysical phenomena. For example, it is commonly believed that uncertainties in the 22Ne(p,g)23Na reaction rate at temperatures relevant to thermally-pulsing asymptotic giant branch stars are largely responsible for our inability to explain the observed sodium-oxygen anti-correlation in globular clusters. With this motivation, resonances in the 22Ne(p,g) 23Na reaction at E_{c.m.} = 458, 417, 178, and 151 keV were measured. The direct-capture contribution was also measured at E_{lab} = 425 keV. It was determined that the 22Ne(p,g)23Na reaction rate in the astrophysically relevant temperature range is dominated by the resonances at 178 and 151 keV and that the total reaction rate is greater than the previously assumed rate by a factor of approximately ˜40 at 0.15 GK. This increased reaction rate impacts the expected nucleosynthesis that occurs in these stars and will shed light onto the origin of this anti-correlation as it is incorporated into

Boron-selective reactions as powerful tools for modular synthesis of diverse complex molecules.

PubMed

Xu, Liang; Zhang, Shuai; Li, Pengfei

2015-12-21

In the context of modular and rapid construction of molecular diversity and complexity for applications in organic synthesis, biomedical and materials sciences, a generally useful strategy has emerged based on boron-selective chemical transformations. In the last decade, these types of reactions have evolved from proof-of-concept to some advanced applications in the efficient preparation of complex natural products and even automated precise manufacturing on the molecular level. These advances have shown the great potential of boron-selective reactions in simplifying synthetic design and experimental operations, and should inspire new developments in related chemical and technological areas. This tutorial review will highlight the original contributions and representative advances in this emerging field.

Iminium and enamine catalysis in enantioselective photochemical reactions.

PubMed

Zou, You-Quan; Hörmann, Fabian M; Bach, Thorsten

2018-01-22

Although enantioselective catalysis under thermal conditions has been well established over the last few decades, the enantioselective catalysis of photochemical reactions is still a challenging task resulting from the complex enantiotopic face differentiation in the photoexcited state. Recently, remarkable achievements have been reported by a synergistic combination of organocatalysis and photocatalysis, which have led to the expedient construction of a diverse range of enantioenriched molecules which are generally not easily accessible under thermal conditions. In this tutorial review, we summarize and highlight the most significant advances in iminium and enamine catalysis of enantioselective photochemical reactions, with an emphasis on catalytic modes and reaction types.

Iminium and enamine catalysis in enantioselective photochemical reactions

PubMed Central

Hörmann, Fabian M.

2018-01-01

Although enantioselective catalysis under thermal conditions has been well established over the last few decades, the enantioselective catalysis of photochemical reactions is still a challenging task resulting from the complex enantiotopic face differentiation in the photoexcited state. Recently, remarkable achievements have been reported by a synergistic combination of organocatalysis and photocatalysis, which have led to the expedient construction of a diverse range of enantioenriched molecules which are generally not easily accessible under thermal conditions. In this tutorial review, we summarize and highlight the most significant advances in iminium and enamine catalysis of enantioselective photochemical reactions, with an emphasis on catalytic modes and reaction types. PMID:29155908

Crosslines, fluorophores in the AGE-related cross-linked proteins.

PubMed

Ienaga, K; Nakamura, K; Hochi, T; Nakazawa, Y; Fukunaga, Y; Kakita, H; Nakano, K

1995-01-01

We can summarize our results as follows: (1) A pair of fluorescent crosslines were isolated from the Maillard reaction mixture; (2) AGE-proteins contained crossline-like structures, and (3) crossline-like immunoreactivities were accumulated in renal tissues of diabetic rats. From these results we concluded that fluorophores in AGE proteins have crossline-like structures and we had the first indication that XLs could be markers for renal disorders.

Recent advances in computational actinoid chemistry.

PubMed

Wang, Dongqi; van Gunsteren, Wilfred F; Chai, Zhifang

2012-09-07

We briefly review advances in computational actinoid (An) chemistry during the past ten years in regard to two issues: the geometrical and electronic structures, and reactions. The former addresses the An-O, An-C, and M-An (M is a metal atom including An) bonds in the actinoid molecular systems, including actinoid oxo and oxide species, actinoid-carbenoid, dinuclear and diatomic systems, and the latter the hydration and ligand exchange, the disproportionation, the oxidation, the reduction of uranyl, hydroamination, and the photolysis of uranium azide. Concerning their relevance to the electronic structures and reactions of actinoids and their importance in the development of an advanced nuclear fuel cycle, we also mentioned the work on actinoid carbides and nitrides, which have been proposed to be candidates of the next generation of nuclear fuel, and the oxidation of PuO(x), which is important to understand the speciation of actinoids in the environment, followed by a brief discussion on the urgent need for a heavier involvement of computational actinoid chemistry in developing advanced reprocessing protocols of spent nuclear fuel. The paper is concluded with an outlook.

Stereospecificity of NAD+/NADH Reactions: A Project Experiment for Advanced Undergraduates.

ERIC Educational Resources Information Center

Lowrey, Jonathan S.; And Others

1981-01-01

Presents background information, materials needed, and experimental procedures to study enzymes dependent on pyridine nucleotide coenzymes (NAD/NADH). The experiments, suitable for advanced organic or biochemistry courses, require approximately 10-15 hours to complete. (SK)

DOE Office of Scientific and Technical Information (OSTI.GOV)

Hull, C.J.; Thorpe, S.R.; Baynes, J.W.

Lysozyme (LZM) was used as a model protein for studies on the effects of oxygen on the Maillard reaction. During a 4 wk incubation in 0.25 M glucose (0.2 M phosphate buffer, pH 7.4, 37/sup 0/C) the kinetics of glycation of LZM were similar under air and N/sub 2/, yielding approx.2 mol Lys modified per mol LZM. Fructoselysine (FL) was the major Lys derivative formed under air and N/sub 2/, while N/sup epsilon/-carboxymethyllysine (CML) accounted for approx.30% of FL formed at 4 wk under air. A loss of 1 mol Arg per mol LZM was also observed under both airmore » and N/sub 2/, with greater loss from LZM dimer vs. monomer, suggesting a role for Arg in the crosslinking reaction. Dimer and monomer did not differ in content of Lys, FL or CML (under air), but dimer was 4 times as fluorescent as monomer, suggesting that crosslink structures are fluorescent. Despite significant differences in kinetics of crosslinking, browning and development of fluorescence of LZM under air vs. N/sub 2/, products formed had similar absorbance and fluorescence spectra. Based on inhibition by chelators and radical scavengers, the more rapid crosslinking and development of fluorescence under air was shown to result from oxygen radical reactions. These results indicate that both radical and non-radical processes may contribute to the Maillard reaction, but that the browning, fluorescence and crosslinking of protein may proceed in the absence of oxygen and oxygen radicals.« less

Genetic Association of Curative and Adverse Reactions to Tyrosine Kinase Inhibitors in Chinese advanced Non-Small Cell Lung Cancer patients

PubMed Central

Ruan, Yunfeng; Jiang, Jie; Guo, Liang; Li, Yan; Huang, Hailiang; Shen, Lu; Luan, Mengqi; Li, Mo; Du, Huihui; Ma, Cheng; He, Lin; Zhang, Xiaoqing; Qin, Shengying

2016-01-01

Epidermal growth factor receptor (EGFR) Tyrosine kinase inhibitor (TKI) is an effective targeted therapy for advanced non-small cell lung cancer (NSCLC) but also causes adverse drug reactions (ADRs) e.g., skin rash and diarrhea. SNPs in the EGFR signal pathway, drug metabolism/ transport pathways and miRNA might contribute to the interpersonal difference in ADRs but biomarkers for therapeutic responses and ADRs to TKIs in Chinese population are yet to be fully investigated. We recruited 226 Chinese advanced NSCLC patients who received TKIs erlotinib, gefitinib and icotinib hydrochloride and systematically studied the genetic factors associated with therapeutic responses and ADRs. Rs884225 (T > C) in EGFR 3′ UTR was significantly associated with lower risk of ADRs to erlotinib (p value = 0.0010, adjusted p value = 0.042). A multivariant interaction four-SNP model (rs884225 in EGFR 3′UTR, rs7787082 in ABCB1 intron, rs38845 in MET intron and rs3803300 in AKT1 5′UTR) was associated with ADRs in general and the more specific drug induced skin injury. The SNPs associated with both therapeutic responses and ADRs indicates they might share a common genetic basis. Our study provided potential biomarkers and clues for further research of biomarkers for therapeutic responses and ADRs in Chinese NSCLC patients. PMID:26988277

Drug metabolism and hypersensitivity reactions to drugs.

PubMed

Agúndez, José A G; Mayorga, Cristobalina; García-Martin, Elena

2015-08-01

The aim of the present review was to discuss recent advances supporting a role of drug metabolism, and particularly of the generation of reactive metabolites, in hypersensitivity reactions to drugs. The development of novel mass-spectrometry procedures has allowed the identification of reactive metabolites from drugs known to be involved in hypersensitivity reactions, including amoxicillin and nonsteroidal antiinflammatory drugs such as aspirin, diclofenac or metamizole. Recent studies demonstrated that reactive metabolites may efficiently bind plasma proteins, thus suggesting that drug metabolites, rather than - or in addition to - parent drugs, may elicit an immune response. As drug metabolic profiles are often determined by variability in the genes coding for drug-metabolizing enzymes, it is conceivable that an altered drug metabolism may predispose to the generation of reactive drug metabolites and hence to hypersensitivity reactions. These findings support the potential for the use of pharmacogenomics tests in hypersensitivity (type B) adverse reactions, in addition to the well known utility of these tests in type A adverse reactions. Growing evidence supports a link between genetically determined drug metabolism, altered metabolic profiles, generation of highly reactive metabolites and haptenization. Additional research is required to developing robust biomarkers for drug-induced hypersensitivity reactions.

Advances in R&D in near-infrared spectroscopy in Japan

NASA Astrophysics Data System (ADS)

Kawano, Sumio; Iwamoto, Mutsuo

1991-02-01

More than 20 years ago when Mr. K. H. Norris firstly introduced the near infrared spectroscopy (NIRS) as a powerful technology in the field of composition analysis of cereals those who were interested in the area of classical spectroscopy would not like to recognize its potential. This tendency still remains at present however it leaves no room for doubt that from viewpoints of applied spectroscopy the NIRS has consolidated its position. From a viewpoint of NIRS application in the field of nondestructive or non invasive measuring techniques history of this technology is only the last decade in Japan. However since the technology was firstly introduced to composition analysis of agricultural commodities in the same manner as in other countries R and D have been growing more actively in diversified fields such as agriculture and industry as well as medical science. In addition the NIRS technology are becoming of general interest by combining other techniques to create various hyphenated instrumentations such as FTNIR MCFTNIR NIRCT and NIR-NMR. In this paper new trends of R D on NIR spectroscopy which are being conducted in Japan will be reviewed. 2. S1JMMARY OF PRESENT R D ON NIRS IN JAPAN NIRS applications reported in the last 3 years are summarized in Table 1. Table 1 Applications of NIRS in Japan Application for Agriculture Taste evaluation of rice and coffee Determination of chemical compositions rice for breeding Determination of chemical compositions in tea Determination of sugar contents in intact peaches Japanese pears Satsuma oranges and apples Determination of sugars and acids in intact tomatoes Determination of forage composition Application for Industry Analysis of state of water in foods Application of analyzing Maillard Reaction''s Process Pattern recognition of NIR spectra as related to process control of roasting coffee beans Quality control of tea processing Determination of moisture content of Surimi products 2 / SPIE Vol. 1379 Optics in Agriculture

Physarum machines: encapsulating reaction-diffusion to compute spanning tree

NASA Astrophysics Data System (ADS)

Adamatzky, Andrew

2007-12-01

The Physarum machine is a biological computing device, which employs plasmodium of Physarum polycephalum as an unconventional computing substrate. A reaction-diffusion computer is a chemical computing device that computes by propagating diffusive or excitation wave fronts. Reaction-diffusion computers, despite being computationally universal machines, are unable to construct certain classes of proximity graphs without the assistance of an external computing device. I demonstrate that the problem can be solved if the reaction-diffusion system is enclosed in a membrane with few ‘growth points’, sites guiding the pattern propagation. Experimental approximation of spanning trees by P. polycephalum slime mold demonstrates the feasibility of the approach. Findings provided advance theory of reaction-diffusion computation by enriching it with ideas of slime mold computation.

Advances in allergic skin disease, anaphylaxis, and hypersensitivity reactions to foods, drugs, and insects in 2011.

PubMed

Sicherer, Scott H; Leung, Donald Y M

2012-01-01

This review highlights some of the research advances in anaphylaxis; hypersensitivity reactions to foods, drugs, and insects; and allergic skin diseases that were reported in the Journal in 2011. Food allergy appears to be increasing in prevalence and carries a strong economic burden. Risk factors can include dietary ones, such as deficiency of vitamin D and timing of complementary foods, and genetic factors, such as filaggrin loss-of-function mutations. Novel mechanisms underlying food allergy include the role of invariant natural killer T cells and influences of dietary components, such as isoflavones. Among numerous preclinical and clinical treatment studies, promising observations include the efficacy of sublingual and oral immunotherapy, a Chinese herbal remedy showing promising in vitro results, the potential immunotherapeutic effects of having children ingest foods with baked-in milk if they tolerate it, and the use of anti-IgE with or without concomitant immunotherapy. Studies of allergic skin diseases, anaphylaxis, and hypersensitivity to drugs and insect venom are elucidating cellular mechanisms, improved diagnostics, and potential targets for future treatment. The role of skin barrier abnormalities, as well as the modulatory effects of the innate and adaptive immune responses, are major areas of investigation. Copyright © 2012 American Academy of Allergy, Asthma & Immunology. Published by Mosby, Inc. All rights reserved.

Recent Advances in Developing Platinum Monolayer Electrocatalysts for the O2 Reduction Reaction

DOE Office of Scientific and Technical Information (OSTI.GOV)

Vukmirovic,M.B.; Sasaki, K.; Zhou, W.-P.

2008-09-15

For Pt, the best single-element catalyst for many reactions, the question of content and loading is exceedingly important because of its price and availability. Using platinum as a fuel-cell catalyst in automotive applications will cause an unquantifiable increase in the demand for this metal. This big obstacle for using fuel cells in electric cars must be solved by decreasing the content of Pt, which is a great challenge of electrocatalysis Over the last several years we inaugurated a new class of electrocatalysts for the oxygen reduction reaction (ORR) based on a monolayer of Pt deposited on metal or alloy carbon-supportedmore » nanoparticles. The possibility of decreasing the Pt content in the ORR catalysts down to a monolayer level has a considerable importance because this reaction requires high loadings due to its slow kinetics. The Pt-monolayer approach has several unique features and some of them are: high Pt utilization, enhanced (or decreased) activity, enhanced stability, and direct activity correlations. The synthesis of Pt monolayer (ML) electrocatalysts was facilitated by our new synthesis method which allowed us to deposit a monolayer of Pt on various metals, or alloy nanoparticles [1, 2] for the cathode electrocatalyst. In this synthesis approach Pt is laid down by the galvanically displacing a Cu monolayer, which was deposited at underpotentials in a monolayer-limited reaction on appropriate metal substrate, with Pt after immersing the electrode in a K{sub 2}PtCl{sub 4} solution.« less

Heterogeneous reactions in aircraft gas turbine engines

NASA Astrophysics Data System (ADS)

Brown, R. C.; Miake-Lye, R. C.; Lukachko, S. P.; Waitz, I. A.

2002-05-01

One-dimensional flow models and unity probability heterogeneous rate parameters are used to estimate the maximum effect of heterogeneous reactions on trace species evolution in aircraft gas turbines. The analysis includes reactions on soot particulates and turbine/nozzle material surfaces. Results for a representative advanced subsonic engine indicate the net change in reactant mixing ratios due to heterogeneous reactions is <10-6 for O2, CO2, and H2O, and <10-10 for minor combustion products such as SO2 and NO2. The change in the mixing ratios relative to the initial values is <0.01%. Since these estimates are based on heterogeneous reaction probabilities of unity, the actual changes will be even lower. Thus, heterogeneous chemistry within the engine cannot explain the high conversion of SO2 to SO3 which some wake models require to explain the observed levels of volatile aerosols. Furthermore, turbine heterogeneous processes will not effect exhaust NOx or NOy levels.

Physicochemical Characterization of a Heat Treated Calcium Alginate Dry Film Prepared with Chicken Stock.

PubMed

Báez, Germán D; Piccirilli, Gisela N; Ballerini, Griselda A; Frattini, Agustín; Busti, Pablo A; Verdini, Roxana A; Delorenzi, Néstor J

2017-04-01

Solid sodium alginate was dissolved into chicken stock in order to give a final alginate concentration of 0.9 percent (w/v). Calcium ions present in chicken stock were enough to induce ionic gelation. After drying, Fourier transform infrared spectroscopy, thickness and mechanical properties of films obtained were determined. Calcium alginate-chicken stock films were heated at 130 °C for different times between 0 and 15 min. Mechanical and optical studies, differential scanning calorimetry, visual aspect and scanning electron microscopy were carried out to describe physicochemical properties of heat treated films. Heating developed a maroon ochre color and increased the brittleness (crispness) of the films related to the intensity of the treatment. Differential scanning thermometry and study on appearance of the films suggested that Maillard reactions may be responsible for the observed changes. Maillard reactions mainly occurred between reducing sugar monomers and free amino groups of gelatin peptides present in the chicken stock, and between alginate and gelatin peptides to a lesser extent. In addition, the plasticizing effect of fat added with chicken stock was also studied. These studies suggest a potential use of heat treated chicken stock films as a substitute of roasted chicken skin. © 2017 Institute of Food Technologists®.

Detection of noncarboxymethyllysine and carboxymethyllysine advanced glycation end products (AGE) in serum of diabetic patients.

PubMed Central

Takeuchi, M.; Makita, Z.; Yanagisawa, K.; Kameda, Y.; Koike, T.

1999-01-01

BACKGROUND: The advanced stage of the Maillard reaction, which leads to the formation of advanced glycation end products (AGE), plays an important role in the pathogenesis of angiopathy in diabetic patients and in the aging process. N(epsilon)-(carboxymethyl)lysine (CML) is thought to be an important epitope for many of currently available AGE antibodies. However, recent findings have indicated that a major source of CML may be by pathways other than glycation. A distinction between CML and non-CML AGE may increase our understanding of AGE formation in vivo. In the present study, we prepared antibodies directed against CML and non-CML AGE. MATERIALS AND METHODS: AGE-rabbit serum albumin prepared by 4, 8, and 12 weeks of incubation with glucose was used to immunize rabbits, and a high-titer AGE-specific antiserum was obtained without affinity for the carrier protein. To separate CML and non-CML AGE antibodies, the anti-AGE antiserum was subjected to affinity chromatography on a column coupled with AGE-BSA and CML-BSA. Two different antibodies were obtained, one reacting specifically with CML and the other reacting with non-CML AGE. Circulating levels of CML and non-CML AGE were measured in 66 type 2 diabetic patients without uremia by means of the competitive ELISA. Size distribution and clearance by hemodialysis detected by non-CML AGE and CML were assessed in serum from diabetic patients on hemodialysis. RESULTS: The serum non-CML AGE level in type 2 diabetic patients was significantly correlated with the mean fasting blood glucose level over the previous 2 months (r = 0.498, p < 0.0001) or the previous 1 month (r = 0.446, p = 0. 0002) and with HbA(1c) (r = 0.375, p = 0.0019), but the CML AGE level was not correlated with these clinical parameters. The CML and non-CML AGE were detected as four peaks with apparent molecular weights of 200, 65, 1.15, and 0.85 kD. The hemodialysis treatment did not affect the high-molecular-weight protein fractions. Although the low

Effect of Maillard Reacted Peptides on Human Salt Taste and the Amiloride-Insensitive Salt Taste Receptor (TRPV1t)

PubMed Central

Katsumata, Tadayoshi; Nakakuki, Hiroko; Tokunaga, Chikara; Fujii, Noboru; Egi, Makoto; Phan, Tam-Hao T.; Mummalaneni, Shobha; DeSimone, John A.

2008-01-01

Maillard reacted peptides (MRPs) were synthesized by conjugating a peptide fraction (1000–5000 Da) purified from soy protein hydrolyzate with galacturonic acid, glucosamine, xylose, fructose, or glucose. The effect of MRPs was investigated on human salt taste and on the chorda tympani (CT) taste nerve responses to NaCl in Sprague–Dawley rats, wild-type, and transient receptor potential vanilloid 1 (TRPV1) knockout mice. MRPs produced a biphasic effect on human salt taste perception and on the CT responses in rats and wild-type mice in the presence of NaCl + benzamil (Bz, a blocker of epithelial Na+ channels), enhancing the NaCl response at low concentrations and suppressing it at high concentrations. The effectiveness of MRPs as salt taste enhancers varied with the conjugated sugar moiety: galacturonic acid = glucosamine > xylose > fructose > glucose. The concentrations at which MRPs enhanced human salt taste were significantly lower than the concentrations of MRPs that produced increase in the NaCl CT response. Elevated temperature, resiniferatoxin, capsaicin, and ethanol produced additive effects on the NaCl CT responses in the presence of MRPs. Elevated temperature and ethanol also enhanced human salt taste perception. N-(3-methoxyphenyl)-4-chlorocinnamid (a blocker of TRPV1t) inhibited the Bz-insensitive NaCl CT responses in the absence and presence of MRPs. TRPV1 knockout mice demonstrated no Bz-insensitive NaCl CT response in the absence or presence of MRPs. The results suggest that MRPs modulate human salt taste and the NaCl + Bz CT responses by interacting with TRPV1t. PMID:18603652

Advanced oxidation of acridine orange by aqueous alkaline iodine.

PubMed

Azmat, Rafia; Qamar, Noshab; Naz, Raheela; Khursheed, Anum

2016-11-01

The advanced oxidation process is certainly used for the dye waste water treatment. In this continuation a new advanced oxidation via aqueous alkaline iodine was developed for the oxidation of acridine orange (AO) {3, 6 -bis (dimethylamino) acridine zinc chloride double salt}. Oxidation Kinetics of AO by alkaline solution of iodine was investigated spectrophotometrically at λ max 491 nm. The reaction was monitored at various operational parameters like several concentrations of dye and iodine, pH, salt electrolyte and temperature. The initial steps of oxidation kinetics followed fractional order reaction with respect to the dye while depend upon the incremental amount of iodine to certain extent whereas maximum oxidation of AO was achieved at high pH. Decline in the reaction rate in the presence of salt electrolyte suggested the presence of oppositely charged species in the rate determining step. Kinetic data revealed that the de-colorization mechanism involves triodate (I 3 - ) species, instead of hypoidate (OI - ) and hypiodous acid (HOI), in alkaline medium during the photo-excitation of hydrolyzed AO. Alleviated concentration of alkali result in decreasing of rate of reaction, clearly indicate that the iodine species are active oxidizing species instead of OH radical. Activation parameters at elevated temperatures were determined which revealed that highly solvated state of dye complex existed into solution. Reaction mixture was subjected to UV/Visible and GC mass spectrum analysis that proves the secondary consecutive reaction was operative in rate determining step and finally dye complex end into smaller fragments.

Systematic analysis of advanced fusion fuel in inertial fusion energy

NASA Astrophysics Data System (ADS)

Velarde, G.; Eliezer, S.; Henis, Z.; Piera, M.; Martinez-Val, J. M.

1997-04-01

Aneutronic fusion reactions can be considered as the cleanest way to exploit nuclear energy. However, these reactions present in general two main drawbacks.—very high temperatures are needed to reach relevant values of their cross sections—Moderate (and even low) energy yield per reaction. This value is still lower if measured in relation to the Z number of the reacting particles. It is already known that bremsstrahlung overruns the plasma reheating by fusion born charged-particles in most of the advanced fuels. This is for instance the case for proton-boron-11 fusion in a stoichiometric plasma and is also so in lithium isotopes fusion reactions. In this paper, the use of deuterium-tritium seeding is suggested to allow to reach higher burnup fractions of advanced fuels, starting at a lower ignition temperature. Of course, neutron production increases as DT contents does. Nevertheless, the ratio of neutron production to energy generation is much lower in DT-advanced fuel mixtures than in pure DT plasmas. One of the main findings of this work is that some natural resources (as D and Li-7) can be burned-up in a catalytic regime for tritium. In this case, neither external tritium breeding nor tritium storage are needed, because the tritium inventory after the fusion burst is the same as before it. The fusion reactor can thus operate on a pure recycling of a small tritium inventory.

Rare, medium, or well done? The effect of heating and food matrix on food protein allergenicity.

PubMed

Nowak-Wegrzyn, Anna; Fiocchi, Alessandro

2009-06-01

To review recent advances in the area of food allergen processing and the effect on protein allergenicity. Heating generally decreases protein allergenicity by destroying conformational epitopes. In peanut and shrimp, heat-induced Maillard reaction (glycation) may increase allergenicity. The majority of milk and egg-allergic children tolerate extensively heated (baked with wheat matrix) milk and egg. Introduction of extensively heated milk and egg proteins is associated with decreasing sizes of skin prick test wheals and increasing serum food-specific IgG4 levels. Heating and other methods of food processing have different effects on food allergens, even those contained in the same complex food. Structural homology does not reliably predict the effect of processing on allergenicity, and individual food allergens have to be tested. Interactions with other proteins, fat, and carbohydrates in the food matrix are complex and poorly understood. Introduction of extensively heated milk and egg proteins into the diet of allergic children may represent an alternative approach to oral tolerance induction. Better characterization of these aspects of food allergy is critical for elucidation of food protein interactions with the gut-associated lymphoid tissue, the ability to induce IgE sensitization, the potential to trigger hypersensitivity reactions, and different clinical phenotypes of food allergy with regard to severity and persistence.

Taking the plunge: chemical reaction dynamics in liquids.

PubMed

Orr-Ewing, Andrew J

2017-12-11

The dynamics of chemical reactions in liquid solutions are now amenable to direct study using ultrafast laser spectroscopy techniques and advances in computer simulation methods. The surrounding solvent affects the chemical reaction dynamics in numerous ways, which include: (i) formation of complexes between reactants and solvent molecules; (ii) modifications to transition state energies and structures relative to the reactants and products; (iii) coupling between the motions of the reacting molecules and the solvent modes, and exchange of energy; (iv) solvent caging of reactants and products; and (v) structural changes to the solvation shells in response to the changing chemical identity of the solutes, on timescales which may be slower than the reactive events. This article reviews progress in the study of bimolecular chemical reaction dynamics in solution, concentrating on reactions which occur on ground electronic states. It illustrates this progress with reference to recent experimental and computational studies, and considers how the various ways in which a solvent affects the chemical reaction dynamics can be unravelled. Implications are considered for research in fields such as mechanistic synthetic chemistry.

The Inhibition of Maillard Browning by Different Concentrations of Rosmarinic Acid and Epigallocatechin-3-Gallate in Model, Bakery, and Fruit Systems.

PubMed

Favreau-Farhadi, Nicole; Pecukonis, Lauren; Barrett, Ann

2015-10-01

Rosmarinic acid and Epigallocatechin gallate concentrations were studied as natural inhibitors of Maillard browning in glucose/glycine model systems, and in bakery rolls and applesauce. The concentrations of the inhibitors were varied to determine the highest level of inhibition without a pro-oxidant/browning effect. UV absorbance and gas chromatography/mass spec (GC/MS) with solid phase microextraction (SPME) sampling was used to study browning in the model systems. Hunter L*, a*, b* was used to analyze the color change results of the inhibitors on applesauce and bakery rolls. It was determined that a 1.0% solution of either antioxidant in the glucose/glycine system produced the greatest inhibition and a synergistic effect was not apparent when the two were combined. Inhibition of browning and a lack of synergy between the antioxidants were also determined in food systems consisting of applesauce and bakery rolls. GC/MS analysis of the model system revealed a high level of pyrazine formation in no-inhibitor control samples and the absence of pyrazines in inhibitor-containing samples. Natural browning inhibitors, that is Rosmarinic acid and Epigallocatechin gallate, can be added to food items to inhibit browning over a prolonged period of storage in order to increase product shelf stability. The concentrations of the inhibitors require optimization since a pro-oxidant effect and increased browning will occur at high levels. Published 2015. This article is a U.S. Government work and is in the public domain in the USA.

Effects of yeast stress and pH on 3-monochloropropanediol (3-MCPD)-producing reactions in model dough systems.

PubMed

Hamlet, C G; Sadd, P A

2005-07-01

A major precursor of 3-monochloropropanediol (3-MCPD) in leavened cereal products is glycerol, which is formed as a natural by-product of yeast fermentation. However, yeast metabolism is affected by stresses such as low osmotic pressure from, for example, the incorporation of sugar or salt in the dough recipe. Tests with model doughs have shown that glycerol production was proportional to yeast mass and limited by available sugars, but that high levels of yeast inhibited 3-MCPD formation. The yeast fraction responsible for the inhibition of 3-MCPD in model dough was shown to be the soluble cytosol proteins, and the inhibition mechanism could be explained by the known reactions of 3-MCPD and/or its precursors with ammonia/amino acids (from yeast proteins). Added glucose did not increase the production of glycerol by yeast but it did promote the generation of 3-MCPD in cooked doughs. The latter effect was attributed to the removal of 3-MCPD inhibitors such as ammonia and amino acids by their reactions with added glucose (e.g. Maillard). The thermal generation of organic acids from added glucose also reduced the pH of cooked doughs, so the effect of pH and short-chain organic acids on 3-MCPD generation in dough was measured. There was a good correlation between initial dough pH and the level of 3-MCPD generated. The effect was weaker than that predicted by simple kinetic modelling, suggesting that the involvement of H+ and/or the organic acid was catalytic. The results showed that modifications to dough recipes involving the addition of reducing sugars and/or organic acids can have a significant impact on 3-MPCD generation in bakery products.

Persistent effects of information about internal reactions: ineffectiveness of debriefing.

PubMed

Valins, Stuart

2005-01-01

A process of self-persuasion has been advanced to account for the effects of information about internal reactions on attitudes toward emotional stimuli. To determine whether the results of this cognitive activity would be resistant to debriefing, Ss were shown slides of female nudes while hearing their alleged heart-rate reactions and were subsequently informed that these reactions were part of a deception manipulation. It was found that, although Ss accepted the debriefing, the false information continued to exert an influence on their attitudes toward the nudes. The attitudes of these Ss toward the nudes were the same as those of Ss who were not debriefed.

Shock-induced reaction synthesis of cubic boron nitride

NASA Astrophysics Data System (ADS)

Beason, M. T.; Pauls, J. M.; Gunduz, I. E.; Rouvimov, S.; Manukyan, K. V.; Matouš, K.; Son, S. F.; Mukasyan, A.

2018-04-01

Here, we report ultra-fast (0.1-5 μs) shock-induced reactions in the 3B-TiN system, leading to the direct synthesis of cubic boron nitride, which is extremely rare in nature and is the second hardest material known. Composite powders were produced through high-energy ball milling to provide intimate mixing and subsequently shocked using an explosive charge. High-resolution transmission electron microscopy and X-ray diffraction confirm the formation of nanocrystalline grains of c-BN produced during the metathetical reaction between boron and titanium nitride. Our results illustrate the possibility of rapid reactions enabled by high-energy ball milling possibly occurring in the solid state on incredibly short timescales. This process may provide a route for the discovery and fabrication of advanced compounds.

Novel α-Oxoamide Advanced-Glycation Endproducts within the N6-Carboxymethyl Lysine and N6-Carboxyethyl Lysine Reaction Cascades.

PubMed

Baldensperger, Tim; Jost, Tobias; Zipprich, Alexander; Glomb, Marcus A

2018-02-28

The highly reactive α-dicarbonyl compounds glyoxal and methylglyoxal are major precursors of posttranslational protein modifications in vivo. Model incubations of N 2 -t-Boc-lysine and either glyoxal or methylglyoxal were used to further elucidate the underlying mechanisms of the N 6 -carboxymethyl lysine and N 6 -carboxyethyl lysine reaction cascades. After independent synthesis of the authentic reference standards, we were able to detect N 6 -glyoxylyl lysine and N 6 -pyruvoyl lysine for the first time by HPLC-MS 2 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 N 6 -glyoxylyl lysine and N 6 -pyruvoyl lysine in rat livers indeed correlated with liver cirrhosis and aging.

Advanced functionalization of polyhydroxyalkanoate via the UV-initiated thiol-ene click reaction.

PubMed

Tajima, Kenji; Iwamoto, Kosuke; Satoh, Yasuharu; Sakai, Ryosuke; Satoh, Toshifumi; Dairi, Tohru

2016-05-01

Polyhydroxyalkanoates (PHAs) incorporating vinyl-bearing 3-hydroxyalkanoates were prepared in 8.5-12.9 g L(-1) yield. The molar ratios (0-16 mol%) of the vinyl-bearing 3-hydroxyalkanoate derivatives were controlled by the continuous feeding of undecylenate at various concentrations. Subsequently, the PHAs were functionalized by UV-initiated thiol-ene click reaction and chemical modification. (1)H NMR spectra suggested that 3-mercaptopropionic acid and 2-aminoethanethiol were successfully introduced into the vinyl-bearing PHA. Subsequently, chemical modification using fluorescein or a fibronectin active fragment (GRGDS) was attempted. The former yielded a PHA derivative capable of emitting fluorescence under UV irradiation, which was useful for determining the miscibility of PHA in a composite film comprising poly-ʟ-lactic acid (PLLA) and PHA. In the latter case, PHA bearing GRGDS peptides exhibited cell adhesiveness, suggesting that its biocompatibility was improved upon peptide introduction. Taken together, the UV-initiated thiol-ene click reaction was demonstrated to be useful in PHA modification.

Polymerase Chain Reaction for Detection of Systemic Plant Pathogens

USDA-ARS?s Scientific Manuscript database

This chapter outlines the advances and application of the polymerase chain reaction (PCR) since its development in 1984 and its enhancements and applications to detection of viruses, viroids and phytoplasma in pome and stone fruits. PCR is probably the most rapidly and widely adopted technology eve...

A Review on Recent Advances in the Application of Nanocatalysts in A3 Coupling Reactions.

PubMed

Nasrollahzadeh, Mahmoud; Sajjadi, Mohaddeseh; Ghorbannezhad, Fatemeh; Sajadi, S Mohammad

2018-03-14

A 3 coupling is one of the few transition-metal catalyzed carbon-carbon bond forming reactions that have been established as a most direct, efficient and atom-economical synthetic approach to afford propargylamine derivatives using various catalysts. A large number of nanosized heterogeneous catalysts for three-component coupling reactions between an aldehyde, an amine, and a terminal alkyne have been popularly introduced as an A 3 coupling in the last decade. The coupling product has found a broad application as a key intermediate for a variety of heterocyclic useful compounds and numerous biologically active molecules such as β-lactams, conformationally restricted peptides, isosteres, herbicides, fungicides, indolizines, pyrroles, quinolines and therapeutic drug molecules. This review aims to give an overview of the current progress made towards the preparation and application of various nanocatalysts-catalyzed A 3 coupling transformations for the synthesis of propargylamines from 2007 to 2017. Several nanocatalysts based on metal and metal oxide nanoparticles (NPs) such as copper, gold, silver, iron, nickel, cobalt and zinc have successfully been employed in A 3 coupling reactions. Besides, core-shells NPs, polymers, complexes, graphenes, metal-organic frameworks and ionic liquids have also been used in these reactions. Abundant examples have been given in this area. Different aspects of the reactions, disparate methods of preparation of nanocatalysts, characterization and their reusability have been perused. © 2018 The Chemical Society of Japan & Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.

Simulating chemical reactions in ionic liquids using QM/MM methodology.

PubMed

Acevedo, Orlando

2014-12-18

The use of ionic liquids as a reaction medium for chemical reactions has dramatically increased in recent years due in large part to the numerous reported advances in catalysis and organic synthesis. In some extreme cases, ionic liquids have been shown to induce mechanistic changes relative to conventional solvents. Despite the large interest in the solvents, a clear understanding of the molecular factors behind their chemical impact is largely unknown. This feature article reviews our efforts developing and applying mixed quantum and molecular mechanical (QM/MM) methodology to elucidate the microscopic details of how these solvents operate to enhance rates and alter mechanisms for industrially and academically important reactions, e.g., Diels-Alder, Kemp eliminations, nucleophilic aromatic substitutions, and β-eliminations. Explicit solvent representation provided the medium dependence of the activation barriers and atomic-level characterization of the solute-solvent interactions responsible for the experimentally observed "ionic liquid effects". Technical advances are also discussed, including a linear-scaling pairwise electrostatic interaction alternative to Ewald sums, an efficient polynomial fitting method for modeling proton transfers, and the development of a custom ionic liquid OPLS-AA force field.

Copper-catalyzed domino reactions for the synthesis of cyclic compounds.

PubMed

Liao, Qian; Yang, Xianghua; Xi, Chanjuan

2014-09-19

Copper-catalyzed domino reactions are one of the most useful strategies for the construction of various cyclic compounds. In this Synopsis, we mainly focus on the latest advances in copper-catalyzed cross-coupling or addition-initiated domino reactions in the synthesis of cyclic compounds, including double alkenylation of N- or S-nucleophiles, alkenylation or alkynlation followed by cyclization of amides or amines, addition and cyclization of heteroallenes affording heterocycles, and coupling and cyclization of 1,3-dicarbonyl compounds toward heterocycles.

Hadron Cancer Therapy: Role of Nuclear Reactions

DOE R&D Accomplishments Database

Chadwick, M. B.

2000-06-20

Recently it has become feasible to calculate energy deposition and particle transport in the body by proton and neutron radiotherapy beams, using Monte Carlo transport methods. A number of advances have made this possible, including dramatic increases in computer speeds, a better understanding of the microscopic nuclear reaction cross sections, and the development of methods to model the characteristics of the radiation emerging from the accelerator treatment unit. This paper describes the nuclear reaction mechanisms involved, and how the cross sections have been evaluated from theory and experiment, for use in computer simulations of radiation therapy. The simulations will allow the dose delivered to a tumor to be optimized, whilst minimizing the dos given to nearby organs at risk.

Advanced Computer Simulations of Military Incinerators

DTIC Science & Technology

2004-12-01

Reaction Engineering International (REI) has developed advanced computer simulation tools for analyzing chemical demilitarization incinerators. The...Manager, 2003a: Summary of Engineering Design Study Projectile Washout System (PWS) Testing. Assembled Chemical Weapons Alternatives (ACWA), Final... Engineering Design Studies for Demilitarization of Assembled Chemical Weapons at Pueblo Chemical Depot. O’Shea, L. et al, 2003: RIM 57 – Monitoring in

Porphyrin involvement in redshift fluorescence in dentin decay

NASA Astrophysics Data System (ADS)

Slimani, A.; Panayotov, I.; Levallois, B.; Cloitre, T.; Gergely, C.; Bec, N.; Larroque, C.; Tassery, H.; Cuisinier, F.

2014-05-01

The aim of this study was to evaluate the porphyrin involvement in the red fluorescence observed in dental caries with Soprolife® light-induced fluorescence camera in treatments mode (SOPRO, ACTEON Group, La Ciotat, France) and Vistacam® camera (DÜRR DENTAL AG, Bietigheim-Bissingen, Germany). The International Caries Detection and Assessment System (ICDAS) was used to rand the samples. Human teeth cross-sections, ranked from ICDAS score 0 to 6, were examined by epi-fluorescence microscopy and Confocal Raman microscopy. Comparable studies were done with Protoporphyrin IX, Porphyrin I and Pentosidine solutions. An RGB analysis of Soprolife® images was performed using ImageJ Software (1.46r, National Institutes of Health, USA). Fluorescence spectroscopy and MicroRaman spectroscopy revealed the presence of Protoporphyrin IX, in carious enamel, dentin and dental plaque. However, the presence of porphyrin I and pentosidine cannot be excluded. The results indicated that not only porphyrin were implicated in the red fluorescence, Advanced Glygation Endproducts (AGEs) of the Maillard reaction also contributed to this phenomenon.

Recent Advances in the Synthesis of Cyclobutanes by Olefin [2 + 2] Photocycloaddition Reactions

PubMed Central

2016-01-01

The [2 + 2] photocycloaddition is undisputedly the most important and most frequently used photochemical reaction. In this review, it is attempted to cover all recent aspects of [2 + 2] photocycloaddition chemistry with an emphasis on synthetically relevant, regio-, and stereoselective reactions. The review aims to comprehensively discuss relevant work, which was done in the field in the last 20 years (i.e., from 1995 to 2015). Organization of the data follows a subdivision according to mechanism and substrate classes. Cu(I) and PET (photoinduced electron transfer) catalysis are treated separately in sections 2 and 4, whereas the vast majority of photocycloaddition reactions which occur by direct excitation or sensitization are divided within section 3 into individual subsections according to the photochemically excited olefin. PMID:27018601

Ring-Closing Metathesis: An Advanced Guided-Inquiry Experiment for the Organic Laboratory

ERIC Educational Resources Information Center

Schepmann, Hala G.; Mynderse, Michelle

2010-01-01

The design and implementation of an advanced guided-inquiry experiment for the organic laboratory is described. Grubbs's second-generation catalyst is used to effect the ring-closing metathesis of diethyl diallylmalonate. The reaction is carried out under an inert atmosphere at room temperature and monitored by argentic TLC. The crude reaction is…

Cation–hydroxide–water coadsorption inhibits the alkaline hydrogen oxidation reaction

DOE PAGES

Chung, Hoon Taek; Martinez, Ulises; Matanovic, Ivana; ...

2016-10-24

Rotating disk electrode voltammograms and infrared reflection absorption spectra indicate that the hydrogen oxidation reaction of platinum in 0.1 M tetramethylammonium hydroxide solution is adversely impacted by time-dependent and potential-driven cation–hydroxide–water coadsorption. Impedance analysis suggests that the hydrogen oxidation reaction inhibition is mainly caused by the hydrogen diffusion barrier of the coadsorbed trilayer rather than intuitive catalyst site blocking by the adsorbed cation species. Finally, these results give useful insights on how to design ionomeric binders for advanced alkaline membrane fuel cells.

Expanding P450 catalytic reaction space through evolution and engineering

PubMed Central

McIntosh, John A.; Farwell, Christopher C.; Arnold, Frances H.

2014-01-01

Advances in protein and metabolic engineering have led to wider use of enzymes to synthesize important molecules. However, many desirable transformations are not catalyzed by any known enzyme, driving interest in understanding how new enzymes can be created. The cytochrome P450 enzyme family, whose members participate in xenobiotic metabolism and natural products biosynthesis, catalyzes an impressive range of difficult chemical reactions that continues to grow as new enzymes are characterized. Recent work has revealed that P450-derived enzymes can also catalyze useful reactions previously accessible only to synthetic chemistry. The evolution and engineering of these enzymes provides an excellent case study for how to genetically encode new chemistry and expand biology’s reaction space. PMID:24658056

The Comparison of the Contents of Sugar, Amadori, and Heyns Compounds in Fresh and Black Garlic.

PubMed

Yuan, Heng; Sun, Linjuan; Chen, Min; Wang, Jun

2016-07-01

Black garlic is produced through thermal processing and is used as a healthy food throughout the world. Compared with fresh garlic, there are obvious changes in the color, taste, and biological functions of black garlic. To analyze and explain these changes, the contents of water-soluble sugars, fructan, and the key intermediate compounds (Heyns and Amadori) of the Maillard reaction in fresh raw garlic and black garlic were investigated, which were important to control and to evaluate the quality of black garlic. The results showed that the fructan contents in the black garlics were decreased by more than 84.6% compared with the fresh raw garlics, which translated into changes in the fructose and glucose contents. The water-soluble sugar content was drastically increased by values ranging from 187.79% to 790.96%. Therefore, the taste of the black garlic became very sweet. The sucrose content in black garlic was almost equivalent to fresh garlic. The Amadori and Heyns compounds were analyzed by HPLC-MS/MS in multiple reaction monitoring mode using the different characteristic fragment ions of Heyns and Amadori compounds. The total content of the 3 main Amadori and 3 Heyns compounds in black garlic ranged from 762.53 to 280.56 μg/g, which was 40 to 100-fold higher than the values in fresh raw garlic. This result was significant proof that the Maillard reaction in black garlic mainly utilized fructose and glucose, with some amino acids. © 2016 Institute of Food Technologists®

Cofactor engineering for advancing chemical biotechnology.

PubMed

Wang, Yipeng; San, Ka-Yiu; Bennett, George N

2013-12-01

Cofactors provide redox carriers for biosynthetic reactions, catabolic reactions and act as important agents in transfer of energy for the cell. Recent advances in manipulating cofactors include culture conditions or additive alterations, genetic modification of host pathways for increased availability of desired cofactor, changes in enzyme cofactor specificity, and introduction of novel redox partners to form effective circuits for biochemical processes and biocatalysts. Genetic strategies to employ ferredoxin, NADH and NADPH most effectively in natural or novel pathways have improved yield and efficiency of large-scale processes for fuels and chemicals and have been demonstrated with a variety of microbial organisms. Copyright © 2013 Elsevier Ltd. All rights reserved.

Nonenzymatic Reactions above Phospholipid Surfaces of Biological Membranes: Reactivity of Phospholipids and Their Oxidation Derivatives

PubMed Central

Solís-Calero, Christian; Ortega-Castro, Joaquín; Frau, Juan; Muñoz, Francisco

2015-01-01

Phospholipids play multiple and essential roles in cells, as components of biological membranes. Although phospholipid bilayers provide the supporting matrix and surface for many enzymatic reactions, their inherent reactivity and possible catalytic role have not been highlighted. As other biomolecules, phospholipids are frequent targets of nonenzymatic modifications by reactive substances including oxidants and glycating agents which conduct to the formation of advanced lipoxidation end products (ALEs) and advanced glycation end products (AGEs). There are some theoretical studies about the mechanisms of reactions related to these processes on phosphatidylethanolamine surfaces, which hypothesize that cell membrane phospholipids surface environment could enhance some reactions through a catalyst effect. On the other hand, the phospholipid bilayers are susceptible to oxidative damage by oxidant agents as reactive oxygen species (ROS). Molecular dynamics simulations performed on phospholipid bilayers models, which include modified phospholipids by these reactions and subsequent reactions that conduct to formation of ALEs and AGEs, have revealed changes in the molecular interactions and biophysical properties of these bilayers as consequence of these reactions. Then, more studies are desirable which could correlate the biophysics of modified phospholipids with metabolism in processes such as aging and diseases such as diabetes, atherosclerosis, and Alzheimer's disease. PMID:25977746

Solid-state polymerisation via [2+2] cycloaddition reaction involving coordination polymers.

PubMed

Medishetty, Raghavender; Park, In-Hyeok; Lee, Shim Sung; Vittal, Jagadese J

2016-03-14

Highly crystalline metal ions containing organic polymers are potentially useful to manipulate the magnetic and optical properties to make advanced multifunctional materials. However, it is challenging to synthesise monocrystalline metal complexes of organic polymers and single-phase hybrid materials made up of both coordination and organic polymers by traditional solution crystallisation. This requires an entirely different approach in the solid-state by thermal or photo polymerisation of the ligands. Among the photochemical methods available, [2+2] cycloaddition reaction has been recently employed to generate cyclobutane based coordination polymers from the metal complexes. Cyclobutane polymers have also been integrated into coordination polymers in this way. Recent advancements in the construction of polymeric chains of cyclobutane rings through photo-dimerisation reaction in the monocrystalline solids containing metal complexes, coordination polymers and metal-organic framework structures are discussed here.

Inverse electron demand Diels-Alder reactions in chemical biology.

PubMed

Oliveira, B L; Guo, Z; Bernardes, G J L

2017-08-14

The emerging inverse electron demand Diels-Alder (IEDDA) reaction stands out from other bioorthogonal reactions by virtue of its unmatchable kinetics, excellent orthogonality and biocompatibility. With the recent discovery of novel dienophiles and optimal tetrazine coupling partners, attention has now been turned to the use of IEDDA approaches in basic biology, imaging and therapeutics. Here we review this bioorthogonal reaction and its promising applications for live cell and animal studies. We first discuss the key factors that contribute to the fast IEDDA kinetics and describe the most recent advances in the synthesis of tetrazine and dienophile coupling partners. Both coupling partners have been incorporated into proteins for tracking and imaging by use of fluorogenic tetrazines that become strongly fluorescent upon reaction. Selected notable examples of such applications are presented. The exceptional fast kinetics of this catalyst-free reaction, even using low concentrations of coupling partners, make it amenable for in vivo radiolabelling using pretargeting methodologies, which are also discussed. Finally, IEDDA reactions have recently found use in bioorthogonal decaging to activate proteins or drugs in gain-of-function strategies. We conclude by showing applications of the IEDDA reaction in the construction of biomaterials that are used for drug delivery and multimodal imaging, among others. The use and utility of the IEDDA reaction is interdisciplinary and promises to revolutionize chemical biology, radiochemistry and materials science.

Analysis of Advanced Glycation Endproducts in Rat Tail Collagen and Correlation to Tendon Stiffening.

PubMed

Jost, Tobias; Zipprich, Alexander; Glomb, Marcus A

2018-04-18

Methylglyoxal is a major 1,2-dicarbonyl compound in vivo and leads to nonenzymatic protein modifications, known as advanced glycation endproducts. Especially long-lived proteins like collagen are prone to changes of the mechanical or biological function, respectively, by accumulation of Maillard-derived modifications. Specifically, the resulting nonenzymatic cross-link structures in parallel to the natural maturation process of collagen fibrils lead to complications with age or during disease. A novel lysine-lysine amide cross-link derived from methylglyoxal, 2,15-diamino-8-methyl-9-oxo-7,10-diaza-1,16-hexadecanedioic acid, named MOLA, was synthesized and identified in vitro and in vivo. Tail tendons of young, adult, and old rats (3, 12, and 22 months) were enzymatically digested prior to analysis of acid-labile glycation products via liquid chromatography-tandem mass spectrometry (LC-MS/MS). As a result, nine monovalent amino acid modifications, mostly originating from methylglyoxal (36 μmol/mol leucine-equivalents in total), and four glycation cross-links (0.72 μmol/mol glucosepane, 0.24 μmol/mol DODIC (3-deoxyglucosone-derived imidazoline cross-link), 0.04 μmol/mol MODIC (methylglyoxal-derived imidazoline cross-link), 0.34 μmol/mol MOLA) were quantitated in senescent tendon collagen. The results correlated with increased tail tendon breaking time from 10 to 190 min and indicate that methylglyoxal is a major player in the aging process of connective tissue.

Macrocyclic bis-thioureas catalyze stereospecific glycosylation reactions.

PubMed

Park, Yongho; Harper, Kaid C; Kuhl, Nadine; Kwan, Eugene E; Liu, Richard Y; Jacobsen, Eric N

2017-01-13

Carbohydrates are involved in nearly all aspects of biochemistry, but their complex chemical structures present long-standing practical challenges to their synthesis. In particular, stereochemical outcomes in glycosylation reactions are highly dependent on the steric and electronic properties of coupling partners; thus, carbohydrate synthesis is not easily predictable. Here we report the discovery of a macrocyclic bis-thiourea derivative that catalyzes stereospecific invertive substitution pathways of glycosyl chlorides. The utility of the catalyst is demonstrated in the synthesis of trans-1,2-, cis-1,2-, and 2-deoxy-β-glycosides. Mechanistic studies are consistent with a cooperative mechanism in which an electrophile and a nucleophile are simultaneously activated to effect a stereospecific substitution reaction. Copyright © 2017, American Association for the Advancement of Science.

Probing Complex Free-Radical Reaction Pathways of Fuel Model Compounds

DOE Office of Scientific and Technical Information (OSTI.GOV)

Buchanan III, A C; Kidder, Michelle; Beste, Ariana

2012-01-01

Fossil (e.g. coal) and renewable (e.g. woody biomass) organic energy resources have received considerable attention as possible sources of liquid transportation fuels and commodity chemicals. Knowledge of the reactivity of these complex materials has been advanced through fundamental studies of organic compounds that model constituent substructures. In particular, an improved understanding of thermochemical reaction pathways involving free-radical intermediates has arisen from detailed experimental kinetic studies and, more recently, advanced computational investigations. In this presentation, we will discuss our recent investigations of the fundamental pyrolysis pathways of model compounds that represent key substructures in the lignin component of woody biomass withmore » a focus on molecules representative of the dominant beta-O-4 aryl ether linkages. Additional mechanistic insights gleaned from DFT calculations on the kinetics of key elementary reaction steps will also be presented, as well as a few thoughts on the significant contributions of Jim Franz to this area of free radical chemistry.« less

Advanced glycated end-products (AGE) during haemodialysis treatment: discrepant results with different methodologies reflecting the heterogeneity of AGE compounds.

PubMed

Henle, T; Deppisch, R; Beck, W; Hergesell, O; Hänsch, G M; Ritz, E

1999-08-01

There has been much recent interest in accumulation of advanced glycation end-products (AGE) in uraemic patients. Analysis of AGE has been difficult, because commonly used methodologies, i.e. immunodetection assays or fluorescence measurements, reflect group reactivity and are not specific for chemically defined substances. Some investigators measured individual AGE compounds, e.g. pentosidine, carboxymethyllysine, pyrraline or imidazolone, but a systematic assessment of known compounds using specific HPLC methods in diabetic and non-diabetic end-stage renal disease (ESRD) patients during treatment has not been performed. For the present study, the concentrations of early and late products of the Maillard reaction in plasma and ultrafiltrate were monitored during high-flux dialysis sessions in diabetic and non-diabetic patients. AGE were analysed by fluorescence spectroscopy and size exclusion chromatography with fluorescence detection. Specific HPLC methods were used to quantify the Amadori product fructoselysine and the AGE compounds pentosidine and pyrraline in acid or enzymatic hydrolysates. Using size exclusion chromatography, we confirmed a similar fluorescent peak distribution for diabetic and non-diabetic ESRD patients. Main fractions were found at approximately 70, approximately 14 and <2 kDa, confirming results obtained by other authors. In diabetic patients, the fluorescence intensity of the low molecular weight fraction was higher. Uraemic patients differed from controls mainly by the fluorescence of the low molecular weight fraction. The peak spectrum in ultrafiltrates was similar to that in plasma regarding low molecular weight fractions and the 14 kDa peak, but no protein-bound fluorescence was found at 70 kDa. HPLC analysis revealed a significant reduction of plasma pentosidine during high-flux dialysis in non-diabetic (from 9.1+/-5.1 to 8.5+/-4.7 pmol/mg protein; P<0.05) and diabetic patients (from 10.0+/-9.1 to 6.8+/-4.0 pmol/mg protein; P<0

Elucidating reaction mechanisms on quantum computers.

PubMed

Reiher, Markus; Wiebe, Nathan; Svore, Krysta M; Wecker, Dave; Troyer, Matthias

2017-07-18

With rapid recent advances in quantum technology, we are close to the threshold of quantum devices whose computational powers can exceed those of classical supercomputers. Here, we show that a quantum computer can be used to elucidate reaction mechanisms in complex chemical systems, using the open problem of biological nitrogen fixation in nitrogenase as an example. We discuss how quantum computers can augment classical computer simulations used to probe these reaction mechanisms, to significantly increase their accuracy and enable hitherto intractable simulations. Our resource estimates show that, even when taking into account the substantial overhead of quantum error correction, and the need to compile into discrete gate sets, the necessary computations can be performed in reasonable time on small quantum computers. Our results demonstrate that quantum computers will be able to tackle important problems in chemistry without requiring exorbitant resources.

Elucidating reaction mechanisms on quantum computers

PubMed Central

Reiher, Markus; Wiebe, Nathan; Svore, Krysta M.; Wecker, Dave; Troyer, Matthias

2017-01-01

With rapid recent advances in quantum technology, we are close to the threshold of quantum devices whose computational powers can exceed those of classical supercomputers. Here, we show that a quantum computer can be used to elucidate reaction mechanisms in complex chemical systems, using the open problem of biological nitrogen fixation in nitrogenase as an example. We discuss how quantum computers can augment classical computer simulations used to probe these reaction mechanisms, to significantly increase their accuracy and enable hitherto intractable simulations. Our resource estimates show that, even when taking into account the substantial overhead of quantum error correction, and the need to compile into discrete gate sets, the necessary computations can be performed in reasonable time on small quantum computers. Our results demonstrate that quantum computers will be able to tackle important problems in chemistry without requiring exorbitant resources. PMID:28674011

Elucidating reaction mechanisms on quantum computers

NASA Astrophysics Data System (ADS)

Reiher, Markus; Wiebe, Nathan; Svore, Krysta M.; Wecker, Dave; Troyer, Matthias

2017-07-01

With rapid recent advances in quantum technology, we are close to the threshold of quantum devices whose computational powers can exceed those of classical supercomputers. Here, we show that a quantum computer can be used to elucidate reaction mechanisms in complex chemical systems, using the open problem of biological nitrogen fixation in nitrogenase as an example. We discuss how quantum computers can augment classical computer simulations used to probe these reaction mechanisms, to significantly increase their accuracy and enable hitherto intractable simulations. Our resource estimates show that, even when taking into account the substantial overhead of quantum error correction, and the need to compile into discrete gate sets, the necessary computations can be performed in reasonable time on small quantum computers. Our results demonstrate that quantum computers will be able to tackle important problems in chemistry without requiring exorbitant resources.

Regolith Advanced Surface Systems Operations Robot Excavator

NASA Technical Reports Server (NTRS)

Mueller, Robert P.; Smith, Jonathan D.; Ebert, Thomas; Cox, Rachel; Rahmatian, Laila; Wood, James; Schuler, Jason; Nick, Andrew

2013-01-01

The Regolith Advanced Surface Systems Operations Robot (RASSOR) excavator robot is a teleoperated mobility platform with a space regolith excavation capability. This more compact, lightweight design (<50 kg) has counterrotating bucket drums, which results in a net-zero reaction horizontal force due to the self-cancellation of the symmetrical, equal but opposing, digging forces.

Immobility reactions under threat: A contribution to human defensive cascade and PTSD.

PubMed

Volchan, E; Rocha-Rego, V; Bastos, A F; Oliveira, J M; Franklin, C; Gleiser, S; Berger, W; Souza, G G L; Oliveira, L; David, I A; Erthal, F S; Pereira, M G; Figueira, I

2017-05-01

Violence exacts a burden on public health. Gun violence is a major trigger for motor defensive reactions in humans and post-traumatic stress disorder (PTSD) is its main psychiatric sequela. However, studies of the human defensive cascade, especially the motor reactions, are at an early stage. This review focuses on studies that employ stabilometry, a methodology that assesses whole body motor reactions, to address defensive behaviors to violence-related threats. Special attention is given to three reactions: "attentive immobility", "immobility under attack" and "tonic immobility", with emphasis on the latter - a peritraumatic reaction which has been strongly associated with the severity of PTSD. These reactions are characterized by reduced body sway and bradycardia, except tonic immobility that presents robust tachycardia. The advances made by investigations into the immobility reactions of the human defensive cascade contribute to helping to bridge the gap between human and non-human species. Furthermore, progresses in basic research to objectively monitor motor defensive reactions under threat can help to develop a dimensional, trans-diagnostic approach to PTSD. Copyright © 2017 Elsevier Ltd. All rights reserved.

Ab Initio Potential Energy Surfaces and Quantum Dynamics for Polyatomic Bimolecular Reactions.

PubMed

Fu, Bina; Zhang, Dong H

2018-05-08

There has been great progress in the development of potential energy surfaces (PESs) and quantum dynamics calculations in the gas phase. The establishment of a fitting procedure for highly accurate PESs and new developments in quantum reactive scattering on reliable PESs allow accurate characterization of reaction dynamics beyond triatomic systems. This review will give the recent development in our group in constructing ab initio PESs based on neural networks and the time-dependent wave packet calculations for bimolecular reactions beyond three atoms. Bimolecular reactions of current interest to the community, namely, OH + H 2 , H + H 2 O, OH + CO, H + CH 4 , and Cl + CH 4 , are focused on. Quantum mechanical characterization of these reactions uncovers interesting dynamical phenomena with an unprecedented level of sophistication and has greatly advanced our understanding of polyatomic reaction dynamics.

Glycation of human cortical and cancellous bone captures differences in the formation of Maillard reaction products between glucose and ribose.

PubMed

Sroga, Grażyna E; Siddula, Alankrita; Vashishth, Deepak

2015-01-01

To better understand some aspects of bone matrix glycation, we used an in vitro glycation approach. Within two weeks, our glycation procedures led to the formation of advanced glycation end products (AGEs) at the levels that corresponded to approx. 25-30 years of the natural in vivo glycation. Cortical and cancellous bones from human tibias were glycated in vitro using either glucose (glucosylation) or ribose (ribosylation). Both glucosylation and ribosylation led to the formation of higher levels of AGEs and pentosidine (PEN) in cancellous than cortical bone dissected from all tested donors (young, middle-age and elderly men and women). More efficient glycation of bone matrix proteins in cancellous bone most likely depended on the higher porosity of this tissue, which facilitated better accessibility of the sugars to the matrix proteins. Notably, glycation of cortical bone from older donors led to much higher AGEs levels as compared to young donors. Such efficient in vitro glycation of older cortical bone could result from aging-related increase in porosity caused by the loss of mineral content. In addition, more pronounced glycation in vivo would be driven by elevated oxidation processes. Interestingly, the levels of PEN formation differed pronouncedly between glucosylation and ribosylation. Ribosylation generated very high levels of PEN (approx. 6- vs. 2.5-fold higher PEN level than in glucosylated samples). Kinetic studies of AGEs and PEN formation in human cortical and cancellous bone matrix confirmed higher accumulation of fluorescent crosslinks for ribosylation. Our results suggest that in vitro glycation of bone using glucose leads to the formation of lower levels of AGEs including PEN, whereas ribosylation appears to support a pathway toward PEN formation. Our studies may help to understand differences in the progression of bone pathologies related to protein glycation by different sugars, and raise awareness for excessive sugar supplementation in food and

Glycation of Human Cortical and Cancellous Bone Captures Differences in the Formation of Maillard Reaction Products between Glucose and Ribose

PubMed Central

Sroga, Grażyna E.; Siddula, Alankrita; Vashishth, Deepak

2015-01-01

To better understand some aspects of bone matrix glycation, we used an in vitro glycation approach. Within two weeks, our glycation procedures led to the formation of advanced glycation end products (AGEs) at the levels that corresponded to approx. 25–30 years of the natural in vivo glycation. Cortical and cancellous bones from human tibias were glycated in vitro using either glucose (glucosylation) or ribose (ribosylation). Both glucosylation and ribosylation led to the formation of higher levels of AGEs and pentosidine (PEN) in cancellous than cortical bone dissected from all tested donors (young, middle-age and elderly men and women). More efficient glycation of bone matrix proteins in cancellous bone most likely depended on the higher porosity of this tissue, which facilitated better accessibility of the sugars to the matrix proteins. Notably, glycation of cortical bone from older donors led to much higher AGEs levels as compared to young donors. Such efficient in vitro glycation of older cortical bone could result from aging-related increase in porosity caused by the loss of mineral content. In addition, more pronounced glycation in vivo would be driven by elevated oxidation processes. Interestingly, the levels of PEN formation differed pronouncedly between glucosylation and ribosylation. Ribosylation generated very high levels of PEN (approx. 6- vs. 2.5-fold higher PEN level than in glucosylated samples). Kinetic studies of AGEs and PEN formation in human cortical and cancellous bone matrix confirmed higher accumulation of fluorescent crosslinks for ribosylation. Our results suggest that in vitro glycation of bone using glucose leads to the formation of lower levels of AGEs including PEN, whereas ribosylation appears to support a pathway toward PEN formation. Our studies may help to understand differences in the progression of bone pathologies related to protein glycation by different sugars, and raise awareness for excessive sugar supplementation in food

Pyrite-Type Nanomaterials for Advanced Electrocatalysis.

PubMed

Gao, Min-Rui; Zheng, Ya-Rong; Jiang, Jun; Yu, Shu-Hong

2017-09-19

Since being proposed by John Bockris in 1970, hydrogen economy has emerged as a very promising alternative to the current hydrocarbon economy. Access to reliable and affordable hydrogen economy, however, requires cost-effective and highly efficient electrocatalytic materials that replace noble metals (e.g., Pt, Ir, Ru) to negotiate electrode processes such as oxygen evolution reaction (OER), hydrogen evolution reaction (HER), and oxygen reduction reaction (ORR). Although substantial advances in the development of inexpensive catalysts, successful deployment of these materials in fuel cells and electrolyzers will depend on their improved activity and robustness. Recent research has demonstrated that the nanostructuring of Earth-abundant minerals provides access to newly advanced energy materials, particularly for nanostructured pyrites, which are attracting great interest. Crystalline pyrites commonly contain the characteristic dianion units and have cations occurring in octahedral coordination-whose generalized formula is MX 2 , where M can be transition metal of groups 8-12 and X is a chalcogen. The diversity of pyrites that are accessible and their versatile and tunable properties make them attractive for a wide range of applications from photovoltaics to energy storage and electrocatalysis. Pyrite-type structures can be further extended to their ternary analogues, for example, CoAsS (cobaltite), NiAsS (gersdorffite), NiSbS (ullmannite), CoPS, and many others. Moreover, improved properties of pyrites can be realized through grafting them with promoter objects (e.g., metal oxides, metal chalcogenides, noble metals, and carbons), which bring favorable interfaces and structural and electronic modulations, thus leading to performance gains. In recent years, research on the synthesis of pyrite nanomaterials and on related structure understanding has dramatically advanced their applications, which offers new perspectives in the search for efficient and robust

Recent advances in the diagnosis of drug allergy.

PubMed

Primeau, M N; Adkinson, N F

2001-08-01

The diagnosis of immunologic drug reactions is based primarily on a detailed clinical history and historical data on relative immunogenicity of the culprit drugs. Except for a few standardized skin tests, most of the other methods for diagnosing drug allergy have unproven diagnostic or predictive clinical utility. Many tests for drug-specific immune responses are suggestive if positive, but have unknown negative predictive values. The present review addresses the most recent published literature regarding the diagnosis of drug allergy. Recent advances in the use of the lymphocyte transformation test, and delayed intradermal skin tests and patch tests for the diagnosis of delayed cutaneous reactions to penicillins suggest that these tests may have clinical utility, although confirmatory reports are still missing. For the diagnosis of acute vaccine reactions, gelatin-specific IgE as measured by radioallergosorbent test has now been shown to be reliably associated with allergic reactions to gelatin-containing vaccines.

Parameterization of N2O5 Reaction Probabilities on the Surface of Particles Containing Ammonium, Sulfate, and Nitrate

EPA Science Inventory

A comprehensive parameterization was developed for the heterogeneous reaction probability (γ) of N₂O₅ as a function of temperature, relative humidity, particle composition, and phase state, for use in advanced air quality models. The reaction probabilities o...

Design of electrocatalysts for oxygen- and hydrogen-involving energy conversion reactions.

PubMed

Jiao, Yan; Zheng, Yao; Jaroniec, Mietek; Qiao, Shi Zhang

2015-04-21

A fundamental change has been achieved in understanding surface electrochemistry due to the profound knowledge of the nature of electrocatalytic processes accumulated over the past several decades and to the recent technological advances in spectroscopy and high resolution imaging. Nowadays one can preferably design electrocatalysts based on the deep theoretical knowledge of electronic structures, via computer-guided engineering of the surface and (electro)chemical properties of materials, followed by the synthesis of practical materials with high performance for specific reactions. This review provides insights into both theoretical and experimental electrochemistry toward a better understanding of a series of key clean energy conversion reactions including oxygen reduction reaction (ORR), oxygen evolution reaction (OER), and hydrogen evolution reaction (HER). The emphasis of this review is on the origin of the electrocatalytic activity of nanostructured catalysts toward the aforementioned reactions by correlating the apparent electrode performance with their intrinsic electrochemical properties. Also, a rational design of electrocatalysts is proposed starting from the most fundamental aspects of the electronic structure engineering to a more practical level of nanotechnological fabrication.

Induced effects of advanced oxidation processes

PubMed Central

Liu, Peng; Li, Chaolin; Zhao, Zhuanjun; Lu, Gang; Cui, Haibo; Zhang, Wenfang

2014-01-01

Hazardous organic wastes from industrial, military, and commercial activities represent one of the greatest challenges to human beings. Advanced oxidation processes (AOPs) are alternatives to the degradation of those organic wastes. However, the knowledge about the exact mechanisms of AOPs is still incomplete. Here we report a phenomenon in the AOPs: induced effects, which is a common property of combustion reaction. Through analysis EDTA oxidation processes by Fenton and UV-Fenton system, the results indicate that, just like combustion, AOPs are typical induction reactions. One most compelling example is that pre-feeding easily oxidizable organic matter can promote the oxidation of refractory organic compound when it was treated by AOPs. Connecting AOPs to combustion, it is possible to achieve some helpful enlightenment from combustion to analyze, predict and understand AOPs. In addition, we assume that maybe other oxidation reactions also have induced effects, such as corrosion, aging and passivation. Muchmore research is necessary to reveal the possibilities of induced effects in those fields. PMID:24503715

Induced effects of advanced oxidation processes.

PubMed

Liu, Peng; Li, Chaolin; Zhao, Zhuanjun; Lu, Gang; Cui, Haibo; Zhang, Wenfang

2014-02-07

Hazardous organic wastes from industrial, military, and commercial activities represent one of the greatest challenges to human beings. Advanced oxidation processes (AOPs) are alternatives to the degradation of those organic wastes. However, the knowledge about the exact mechanisms of AOPs is still incomplete. Here we report a phenomenon in the AOPs: induced effects, which is a common property of combustion reaction. Through analysis EDTA oxidation processes by Fenton and UV-Fenton system, the results indicate that, just like combustion, AOPs are typical induction reactions. One most compelling example is that pre-feeding easily oxidizable organic matter can promote the oxidation of refractory organic compound when it was treated by AOPs. Connecting AOPs to combustion, it is possible to achieve some helpful enlightenment from combustion to analyze, predict and understand AOPs. In addition, we assume that maybe other oxidation reactions also have induced effects, such as corrosion, aging and passivation. Muchmore research is necessary to reveal the possibilities of induced effects in those fields.

Fragrance patch tests prepared in advance may give false-negative reactions.

PubMed

Mowitz, Martin; Svedman, Cecilia; Zimerson, Erik; Bruze, Magnus

2014-11-01

Several of the ingredients in fragrance mix I (FM I) have been shown to evaporate from petrolatum preparations applied in test chambers to an extent that can be suspected to affect the patch test result. To compare the reactivity towards FM I and fragrance mix II (FM II) when they are applied in test chambers in advance and immediately prior to the patch test occasion. Seven hundred and ninety-five consecutive patients were simultaneously patch tested with duplicate samples of FM I and FM II. One sample was applied in the test chamber 6 days in advance (6D sample), and the other sample was applied immediately before the patients were patch tested (fresh sample). Twenty-two (2.8%) patients reacted exclusively to the fresh sample of FM I, 6 (0.7%) reacted exclusively to the 6D sample, and 22 (2.8%) reacted to both samples. The corresponding numbers for FM II were 9 (1.1%) for the fresh sample, 6 (0.7%) for the 6D sample and 12 (1.5%) for both samples. There was a statistically significant difference between the numbers of patients reacting to the fresh and 6D samples of FM I. No corresponding difference was observed for FM II. This can probably be explained by differences in volatilities between the ingredients of FM I and FM II. © 2014 John Wiley & Sons A/S. Published by John Wiley & Sons Ltd.

Nonimmediate hypersensitivity reactions to iodinated contrast media.

PubMed

Gómez, Enrique; Ariza, Adriana; Blanca-López, Natalia; Torres, Maria J

2013-08-01

To provide a detailed analysis of the latest findings on the mechanisms underlying the nonimmediate reactions to iodinated contrast media and comment on the recent advances in diagnosis, focusing on the roles of the skin test, drug provocation test (DPT), and lymphocyte transformation test (LTT). Several studies have reported new findings supporting an important role for T-lymphocytes in the nonimmediate reactions to iodinated contrast media. The LTT has been used as an in-vitro tool for diagnosis, but with variable results. However, the inclusion of autologous monocyte-derived dendritic cells as professional antigen-presenting cells has improved the sensitivity of this test. Regarding in-vivo diagnosis, although skin testing has been routine, it has now been shown that its sensitivity and negative predictive value are low. Recent studies have demonstrated that the DPT is a well tolerated and useful procedure that is necessary to confirm the diagnosis of nonimmediate hypersensitivity reactions to iodinated contrast media. Nonimmediate reactions to contrast media are usually T-cell mediated. Diagnosis is based on skin testing, although its sensitivity and negative predictive value are not optimal. Consequently, drug provocation testing is often needed to confirm the diagnosis and also to seek alternative contrast media that can be tolerated.

Surface-Activated Coupling Reactions Confined on a Surface.

PubMed

Dong, Lei; Liu, Pei Nian; Lin, Nian

2015-10-20

Chemical reactions may take place in a pure phase of gas or liquid or at the interface of two phases (gas-solid or liquid-solid). Recently, the emerging field of "surface-confined coupling reactions" has attracted intensive attention. In this process, reactants, intermediates, and products of a coupling reaction are adsorbed on a solid-vacuum or a solid-liquid interface. The solid surface restricts all reaction steps on the interface, in other words, the reaction takes place within a lower-dimensional, for example, two-dimensional, space. Surface atoms that are fixed in the surface and adatoms that move on the surface often activate the surface-confined coupling reactions. The synergy of surface morphology and activity allow some reactions that are inefficient or prohibited in the gas or liquid phase to proceed efficiently when the reactions are confined on a surface. Over the past decade, dozens of well-known "textbook" coupling reactions have been shown to proceed as surface-confined coupling reactions. In most cases, the surface-confined coupling reactions were discovered by trial and error, and the reaction pathways are largely unknown. It is thus highly desirable to unravel the mechanisms, mechanisms of surface activation in particular, of the surface-confined coupling reactions. Because the reactions take place on surfaces, advanced surface science techniques can be applied to study the surface-confined coupling reactions. Among them, scanning tunneling microscopy (STM) and X-ray photoelectron spectroscopy (XPS) are the two most extensively used experimental tools. The former resolves submolecular structures of individual reactants, intermediates, and products in real space, while the latter monitors the chemical states during the reactions in real time. Combination of the two methods provides unprecedented spatial and temporal information on the reaction pathways. The experimental findings are complemented by theoretical modeling. In particular, density

The kinetics of thermal generation of flavour.

PubMed

Parker, Jane K

2013-01-01

Control and optimisation of flavour is the ultimate challenge for the food and flavour industry. The major route to flavour formation during thermal processing is the Maillard reaction, which is a complex cascade of interdependent reactions initiated by the reaction between a reducing sugar and an amino compound. The complexity of the reaction means that researchers turn to kinetic modelling in order to understand the control points of the reaction and to manipulate the flavour profile. Studies of the kinetics of flavour formation have developed over the past 30 years from single- response empirical models of binary aqueous systems to sophisticated multi-response models in food matrices, based on the underlying chemistry, with the power to predict the formation of some key aroma compounds. This paper discusses in detail the development of kinetic models of thermal generation of flavour and looks at the challenges involved in predicting flavour. Copyright © 2012 Society of Chemical Industry.

The use of D-penicillamine in cystinuria: efficacy and untoward reactions.

PubMed Central

Halperin, E. C.; Thier, S. O.; Rosenberg, L. E.

1981-01-01

A retrospective study was conducted to assess the efficacy of D-penicillamine in the management of cystinuria, as well as to define the frequency and nature of untoward reactions to this drug. Fifty-six individuals were identified who, by stone analysis and/or biochemical studies, met the accepted diagnostic criteria for phenotypic cystinuria. The majority of these patients presented in the second decade of life with evidence of stone formation: renal colic, hematuria, and/or stone passage. Thirty-five individuals were considered to have clinically advanced cystinuria because they had required at least one urinary tract lithotomy. In these advanced cases, frequency of subsequent lithotomies and episodes of renal colic per 100 patient-years of observation were used as indices to measure the efficacy of D-penicillamine treatment. By both measurements, D-penicillamine significantly improved the clinical course of patients. The incidence of acute drug sensitivity reactions (rash, fever, and/or arthropathy) was in excess of 40 percent. Delayed drug-induced proteinuria occurred in 34 percent of treated patients. We conclude that D-penicillamine is useful in the treatment of cystinuria. Because of the significant number of untoward drug reactions, however, we believe the drug should be instituted only in selected, high-risk patients. PMID:7342491

The mechanism of collagen cross-linking in diabetes: a puzzle nearing resolution.

PubMed

Monnier, V M; Glomb, M; Elgawish, A; Sell, D R

1996-07-01

Considerable interest has been focused in recent years on the mechanism of collagen cross-linking by high glucose in vitro and in vivo. Experiments in both diabetic humans and in animals have shown that over time collagen becomes less soluble, less digestible by collagenase, more stable to heat-induced denaturation, and more glycated. In addition, collagen becomes more modified by advanced products of the Maillard reaction, i.e., immunoreactive advanced glycation end products and the glycoxidation markers carboxymethyllysine and pentosidine. Mechanistic studies have shown that collagen cross-linking in vitro can be uncoupled from glycation by the use of antioxidants and chelating agents. Experiments in the authors' laboratory revealed that approximately 50% of carboxymethyllysine formed in vitro originates from pathways other than oxidation of Amadori products, i.e., most likely the oxidation of Schiff base-linked glucose. In addition, the increase in thermal stability of rat tail tendons exposed to high glucose in vitro or in vivo was found to strongly depend on H2O2 formation. The final missing piece of the puzzle is that of the structure of the major cross-link. We speculate that it is a nonfluorescent nonultraviolet active cross-link between two lysine residues, which includes a fragmentation product of glucose linked in a nonreducible bond labile to both strong acids and bases.

Investigation of variations in the acrylamide and N(ε) -(carboxymethyl) lysine contents in cookies during baking.

PubMed

Cheng, Lu; Jin, Cheng; Zhang, Ying

2014-05-01

Baking processing is indispensable to determine special sensory prosperities of cookies and induces the formation of some beneficial components such as antioxidants. However, the formation of some Maillard reaction-derived chemical hazards, such as acrylamide (AA) and N(ε) -(carboxymethyl) lysine (CML) in cookies is also a significant consequence of baking processing from a food safety standpoint. This study investigated the effects of baking conditions on the formation of AA and CML, as well as the antioxidant activity (AOA) of cookies. Cookies were baked at various baking temperatures (155 to 230 °C) and times (1.5 to 31 min). AA and CML contents were determined by ultra-performance liquid chromatography-tandem mass spectrometry, respectively. The highest level of AA was obtained in the cookies baked at 155 °C/21 min and 205 °C/11 min (328.93 ± 3.10 μg/kg and 329.29 ± 5.29 μg/kg), while the highest level of CML was obtained in the cookies baked at 230 °C/1.5 min (118.05 ± 0.21 mg/kg). AA was prone to form at relatively low temperature range (155 to 205 °C), however, CML at relatively high temperature range (205 to 230 °C). The CML content was much higher than the AA content in the same set of cookies, by about 2 to 3 orders of magnitude. The AOA of cookies increased at more severe baking conditions. According to the AA and CML content, AOA and sensory properties of cookies, the temperature-time regime of 180 °C/16 min might be a compromised selection. However, only optimizing the baking condition was not enough for manufacture of high-quality cookies. Cookies, a kind of widely consumed bakery products in the world, contain some potentially harmful compounds, like acrylamide (AA) and N(ε) -(carboxymethyl) lysine (CML). AA in cookies has led to public health concern and several research efforts. But CML, another Maillard reaction-derived chemical hazard, has been neglected so far, even though its content is much higher than that of AA in cookies. The

Recent Advances in Cyanamide Chemistry: Synthesis and Applications.

PubMed

Prabhath, M R Ranga; Williams, Luke; Bhat, Shreesha V; Sharma, Pallavi

2017-04-12

The application of alkyl and aryl substituted cyanamides in synthetic chemistry has diversified multi-fold in recent years. In this review, we discuss recent advances (since 2012) in the chemistry of cyanamides and detail their application in cycloaddition chemistry, aminocyanation reactions, as well as electrophilic cyanide-transfer agents and their unique radical and coordination chemistry.

Assessing the effects of severe heat treatment of milk on calcium bioavailability: in vitro and in vivo studies.

PubMed

Seiquer, I; Delgado-Andrade, C; Haro, A; Navarro, M P

2010-12-01

Thermal processing of milk is a common practice. As milk is the main source of dietary calcium, this study aimed to assess the effects of overheating milk on calcium availability. Thus, thermally damaged milk (overheated, OH, milk; 3 cycles of sterilization at 116 °C, 16 min) was compared with UHT milk (150 °C, 6s) in 2 types of assays: in vitro and in vivo (rats). In addition, the greater Maillard reaction rate associated with thermal treatment in OH milk was confirmed by determining specific (furosine) and unspecific markers (CieLab color). A negative effect on calcium solubility was observed after in vitro digestion of OH milk compared with UHT milk. Feeding rats the diet containing OH milk as the protein source led to significantly lower values of apparent calcium absorption and retention than those found among animals fed the UHT milk diet. Whereas reducing the absorption appears to result mainly from the decreased food intake, the negative effect on retention seems to be due to factors derived from milk thermal damage, such as the formation of Maillard reaction products. It was concluded that milk-processing conditions warrant special attention to prevent impaired dietary calcium utilization. This may be especially important in situations where milk and dairy products are the main dietary components, such as in early infancy. Copyright © 2010 American Dairy Science Association. Published by Elsevier Inc. All rights reserved.

Increase in the free radical scavenging capability of bitter gourd by a heat-drying process.

PubMed

Wei, Lu; Shaoyun, Wang; Shutao, Liu; Jianwu, Zhou; Lijing, Ke; Pingfan, Rao

2013-12-01

Bitter gourd (Momordica charantia Linn.) is widely regarded as one of the best remedy foods for diabetes. The positive effect of bitter gourd on diabetes has been attributed in part to the remarkable free radical scavenging activity of its boiled water extract from sun-dried fruits. It is well known that a heat process significantly influences the antioxidant activity of fresh fruits. However, the heat drying processes of bitter gourd have not been studied so far. Here, we show that the free radical scavenging capability of bitter gourd extract significantly increases after the heat drying process, while the content of flavonoids and phenols, which are generally regarded as the main antioxidant components in bitter gourd, remain unaffected. Furthermore, the content of free amino acids and the total reducing sugar were found to decrease with increasing browning index, indicating the progression of the Maillard reaction, products of which are known to possess significant antioxidant activity. Therefore, it suggests that Maillard reaction products may be the main contributors to the increase in antioxidant capability. Finally, the bitter gourd extract with the higher antioxidant activity, was shown to manifest a corresponding higher proliferation activity on NIT-1 beta-cells. These results suggest that controllable conditions in the heat-drying processing of fresh bitter gourd fruit is of significance for enhancing the total free radical scavenging capacity, beta-cell proliferation activity and possibly the anti-diabetic activity of this fruit.

Development and Application of Asymmetric Organocatalytic Mukaiyama and Vinylogous-Mukaiyama-Type Reactions.

PubMed

Alemán, José; Garrido, Alberto; Fraile, Alberto; Yuste, Francisco; Frias, Maria; Cieslik, Wioleta; Rosado, Anielka

2018-04-23

Organocatalysis is a growing area that is benefiting from advances in many fields. Its implementation has begun in areas such as supramolecular chemistry, organic chemistry and natural product syntheses. While a considerable number of important publications in the field of organocatalytic Mukaiyama-type additions have been reported, they are yet to be fully covered in a review. Therefore, we would like to highlight the applications of various kinds of organocatalysts in Mukaiyama-type reactions, while also including the vinylogous Mukaiyama variant. Herein we describe and discuss the development and current state of the art of the organocatalytic Mukaiyama reaction, vinylogous Mukaiyama and related reactions. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Pentosidine formation in skin correlates with severity of complications in individuals with long-standing IDDM.

PubMed

Sell, D R; Lapolla, A; Odetti, P; Fogarty, J; Monnier, V M

1992-10-01

Pentosidine is an advanced glycosylation end product and protein cross-link that results from the reaction of pentoses with proteins. Recent data indicate that long-term glycation of proteins with glucose also leads to pentosidine formation through sugar fragmentation. In this study, the relationship between the severity of diabetic complications and pentosidine formation was investigated in collagen from skin-punch biopsies from 25 nondiabetic control subjects and 41 IDDM patients with diabetes duration greater than 17 yr. Pentosidine was significantly elevated in all IDDM patients versus control subjects (P less than 0.0001). It correlated strongly with age (P less than 0.0001) and weakly with duration (P less than 0.082). Age-adjusted pentosidine levels were highest in grade 2 (severe) versus grade 1 and 0 complication in all four parameters tested (retinopathy, proteinuria, arterial stiffness, and joint stiffness). Significant differences were found for retinopathy (P less than 0.014) and joint stiffness (P less than 0.041). The highest degree of association was with the cumulative grade of individual complication (P less than 0.005), determined by summing indexes of all four parameters. Pentosidine also was significantly elevated in the serum of IDDM patients compared with control subjects (P less than 0.0001), but levels were not significantly correlated with age, diabetes duration, complication, or skin collagen pentosidine (P greater than 0.05). A high correlation between pentosidine levels and long-wave collagen-linked fluorescence also was observed, suggesting that pentosidine is a generalized marker of accelerated tissue modification by the advanced glycosylation/Maillard reaction, which is enhanced in IDDM patients with severe complications.

Determination of Plasma Screening Effects for Thermonuclear Reactions in Laser-generated Plasmas

NASA Astrophysics Data System (ADS)

Wu, Yuanbin; Pálffy, Adriana

2017-03-01

Due to screening effects, nuclear reactions in astrophysical plasmas may behave differently than in the laboratory. The possibility to determine the magnitude of these screening effects in colliding laser-generated plasmas is investigated theoretically, having as a starting point a proposed experimental setup with two laser beams at the Extreme Light Infrastructure facility. A laser pulse interacting with a solid target produces a plasma through the Target Normal Sheath Acceleration scheme, and this rapidly streaming plasma (ion flow) impacts a secondary plasma created by the interaction of a second laser pulse on a gas jet target. We model this scenario here and calculate the reaction events for the astrophysically relevant reaction 13C(4He, n)16O. We find that it should be experimentally possible to determine the plasma screening enhancement factor for fusion reactions by detecting the difference in reaction events between two scenarios of ion flow interacting with the plasma target and a simple gas target. This provides a way to evaluate nuclear reaction cross-sections in stellar environments and can significantly advance the field of nuclear astrophysics.

Exploring chemical reaction mechanisms through harmonic Fourier beads path optimization.

PubMed

Khavrutskii, Ilja V; Smith, Jason B; Wallqvist, Anders

2013-10-28

Here, we apply the harmonic Fourier beads (HFB) path optimization method to study chemical reactions involving covalent bond breaking and forming on quantum mechanical (QM) and hybrid QM∕molecular mechanical (QM∕MM) potential energy surfaces. To improve efficiency of the path optimization on such computationally demanding potentials, we combined HFB with conjugate gradient (CG) optimization. The combined CG-HFB method was used to study two biologically relevant reactions, namely, L- to D-alanine amino acid inversion and alcohol acylation by amides. The optimized paths revealed several unexpected reaction steps in the gas phase. For example, on the B3LYP∕6-31G(d,p) potential, we found that alanine inversion proceeded via previously unknown intermediates, 2-iminopropane-1,1-diol and 3-amino-3-methyloxiran-2-ol. The CG-HFB method accurately located transition states, aiding in the interpretation of complex reaction mechanisms. Thus, on the B3LYP∕6-31G(d,p) potential, the gas phase activation barriers for the inversion and acylation reactions were 50.5 and 39.9 kcal∕mol, respectively. These barriers determine the spontaneous loss of amino acid chirality and cleavage of peptide bonds in proteins. We conclude that the combined CG-HFB method further advances QM and QM∕MM studies of reaction mechanisms.

Biomarkers of adverse drug reactions.

PubMed

Carr, Daniel F; Pirmohamed, Munir

2018-02-01

Adverse drug reactions can be caused by a wide range of therapeutics. Adverse drug reactions affect many bodily organ systems and vary widely in severity. Milder adverse drug reactions often resolve quickly following withdrawal of the casual drug or sometimes after dose reduction. Some adverse drug reactions are severe and lead to significant organ/tissue injury which can be fatal. Adverse drug reactions also represent a financial burden to both healthcare providers and the pharmaceutical industry. Thus, a number of stakeholders would benefit from development of new, robust biomarkers for the prediction, diagnosis, and prognostication of adverse drug reactions. There has been significant recent progress in identifying predictive genomic biomarkers with the potential to be used in clinical settings to reduce the burden of adverse drug reactions. These have included biomarkers that can be used to alter drug dose (for example, Thiopurine methyltransferase (TPMT) and azathioprine dose) and drug choice. The latter have in particular included human leukocyte antigen (HLA) biomarkers which identify susceptibility to immune-mediated injuries to major organs such as skin, liver, and bone marrow from a variety of drugs. This review covers both the current state of the art with regard to genomic adverse drug reaction biomarkers. We also review circulating biomarkers that have the potential to be used for both diagnosis and prognosis, and have the added advantage of providing mechanistic information. In the future, we will not be relying on single biomarkers (genomic/non-genomic), but on multiple biomarker panels, integrated through the application of different omics technologies, which will provide information on predisposition, early diagnosis, prognosis, and mechanisms. Impact statement • Genetic and circulating biomarkers present significant opportunities to personalize patient therapy to minimize the risk of adverse drug reactions. ADRs are a significant heath issue

High Performance Electrocatalytic Reaction of Hydrogen and Oxygen on Ruthenium Nanoclusters

DOE Office of Scientific and Technical Information (OSTI.GOV)

Ye, Ruquan; Liu, Yuanyue; Peng, Zhiwei

2017-01-18

The development of catalytic materials for the hydrogen oxidation, hydrogen evolution, oxygen reduction or oxygen evolution reactions with high reaction rates and low overpotentials are key goals for the development of renewable energy. We report here Ru(0) nanoclusters supported on nitrogen-doped graphene as high-performance multifunctional catalysts for the hydrogen evolution reaction (HER) and oxygen reduction reaction (ORR), showing activities similar to that of commercial Pt/C in alkaline solution. For HER performance in alkaline media, sample Ru/NG-750 reaches 10 mA cm-2 at an overpotential of 8 mV with a Tafel slope of 30 mV dec-1. The high HER performance in alkalinemore » solution is advantageous because most catalysts for ORR and oxygen evolution reaction (OER) also prefer alkaline solution environment whereas degrade in acidic electrolytes. For ORR performance, Ru/NG effectively catalyzes the conversion of O2 into OH- via a 4e process at a current density comparable to that of Pt/C. The unusual catalytic activities of Ru(0) nanoclusters reported here are important discoveries for the advancement of renewable energy conversion reactions.« less

N-butanol extracts of Morinda citrifolia suppress advanced glycation end products (AGE)-induced inflammatory reactions in endothelial cells through its anti-oxidative properties.

PubMed

Ishibashi, Yuji; Matsui, Takanori; Isami, Fumiyuki; Abe, Yumi; Sakaguchi, Tatsuya; Higashimoto, Yuichiro; Yamagishi, Sho-Ichi

2017-03-04

Advanced glycation end products (AGEs), senescent macroprotein derivatives formed during a normal aging process and acceleratedly under diabetic conditions, play a role in atherosclerotic cardiovascular disease. AGEs cause endothelial cell (EC) damage, an initial trigger for atherosclerosis through the interaction with a receptor for AGEs (RAGE). We have previously shown that n-butanol extracts of Morinda citrifolia (noni), a plant belonging to the family Rubiaceae, block the binding of AGEs to RAGE in vitro. In this study, we examined the effects of n-butanol extracts of noni on reactive oxygen species (ROS) generation and inflammatory reactions on AGE-exposed human umbilical vein ECs (HUVECs). HUVECs were treated with 100 μg/ml AGE-bovine serum albumin (AGE-BSA) or non-glycated BSA in the presence or absence of 670 ng/ml n-butanol extracts of noni for 4 h. Then ROS generation and inflammatory and gene expression in HUVECs were evaluated by dihydroethidium staining and real-time reverse transcription-polymerase chain reaction analyses, respectively. THP-1 cell adhesion to HUVECs was measured after 2-day incubation of AGE-BSA or BSA in the presence or absence of 670 ng/ml n-butanol extracts of noni. N-butanol extracts of noni at 670 ng/ml significantly inhibited the AGE-induced ROS generation and RAGE, intercellular adhesion molecule-1 and plasminogen activator inhibitor-1 gene expressions in HUVECs. AGEs significantly increased monocytic THP-1 cell adhesion to HUVECs, which was also prevented by 670 ng/ml n-butanol extracts of noni. The present study demonstrated for the first time that N-butanol extracts of noni could suppress the AGE-induced inflammatory reactions in HUVECs through its anti-oxidative properties via blocking of the interaction of AGEs with RAGE. Inhibition of the AGE-RAGE axis by n-butanol extracts of noni may be a novel nutraceutical strategy for the treatment of cardiovascular disease.

Skin beautification with oral non-hydrolized versions of carnosine and carcinine: Effective therapeutic management and cosmetic skincare solutions against oxidative glycation and free-radical production as a causal mechanism of diabetic complications and skin aging.

PubMed

Babizhayev, Mark A; Deyev, Anatoliy I; Savel'yeva, Ekaterina L; Lankin, Vadim Z; Yegorov, Yegor E

2012-10-01

Advanced glycation Maillard reaction end products (AGEs) are causing the complications of diabetes and skin aging, primarily via adventitious and cross-linking of proteins. Long-lived proteins such as structural collagen are particularly implicated as pathogenic targets of AGE processes. The formation of α-dicarbonyl compounds represents an important step for cross-linking proteins in the glycation or Maillard reaction. The purpose of this study was to investigate the contribution of glycation coupled to the glycation free-radical oxidation reactions as markers of protein damage in the aging of skin tissue proteins and diabetes. To elucidate the mechanism for the cross-linking reaction, we studied the reaction between a three-carbon α-dicarbonyl compound, methylglyoxal, and amino acids using EPR spectroscopy, a spectrophotometric kinetic assay of superoxide anion production at the site of glycation and a chemiluminescence technique. The transglycating activity, inhibition of transition metal ions peroxidative catalysts, resistance to hydrolysis of carnosine mimetic peptide-based compounds with carnosinase and the protective effects of carnosine, carcinine and related compounds against the oxidative damage of proteins and lipid membranes were assessed in a number of biochemical and model systems. A 4-month randomized, double-blind, controlled study was undertaken including 42 subjects where the oral supplement of non-hydrolized carnosine (Can-C Plus® formulation) was tested against placebo for 3 months followed by a 1-month supplement-free period for both groups to assess lasting effects. Assessment of the age-related skin parameters and oral treatment efficacy measurements included objective skin surface evaluation with Visioscan® VC 98 and visual assessment of skin appearance parameters. The results together confirm that a direct one-electron transfer between a Schiff base methylglyoxal dialkylimine (or its protonated form) and methylglyoxal is responsible for

Tailoring transition-metal hydroxides and oxides by photon-induced reactions

DOE PAGES

Niu, Kai -Yang; Fang, Liang; Ye, Rong; ...

2016-10-18

Controlled synthesis of transition-metal hydroxides and oxides with earth-abundant elements have attracted significant interest because of their wide applications, for example as battery electrode materials or electrocatalysts for fuel generation. Here, we report the tuning of the structure of transition-metal hydroxides and oxides by controlling chemical reactions using an unfocused laser to irradiate the precursor solution. A Nd:YAG laser with wavelengths of 532 nm or 1064 nm was used. The Ni 2+, Mn 2+, and Co 2+ ion-containing aqueous solution undergoes photo-induced reactions and produces hollow metal-oxide nanospheres (Ni 0.18Mn 0.45Co 0.37O x) or core–shell metal hydroxide nanoflowers ([Ni 0.15Mnmore » 0.15Co 0.7(OH) 2](NO 3) 0.2•H 2O), depending on the laser wavelengths. We propose two reaction pathways, either by photo-induced redox reaction or hydrolysis reaction, which are responsible for the formation of distinct nanostructures. As a result, the study of photon-induced materials growth shines light on the rational design of complex nanostructures with advanced functionalities.« less

EMPIRE: Nuclear Reaction Model Code System for Data Evaluation

DOE Office of Scientific and Technical Information (OSTI.GOV)

Herman, M.; Capote, R.; Carlson, B.V.

EMPIRE is a modular system of nuclear reaction codes, comprising various nuclear models, and designed for calculations over a broad range of energies and incident particles. A projectile can be a neutron, proton, any ion (including heavy-ions) or a photon. The energy range extends from the beginning of the unresolved resonance region for neutron-induced reactions ({approx} keV) and goes up to several hundred MeV for heavy-ion induced reactions. The code accounts for the major nuclear reaction mechanisms, including direct, pre-equilibrium and compound nucleus ones. Direct reactions are described by a generalized optical model (ECIS03) or by the simplified coupled-channels approachmore » (CCFUS). The pre-equilibrium mechanism can be treated by a deformation dependent multi-step direct (ORION + TRISTAN) model, by a NVWY multi-step compound one or by either a pre-equilibrium exciton model with cluster emission (PCROSS) or by another with full angular momentum coupling (DEGAS). Finally, the compound nucleus decay is described by the full featured Hauser-Feshbach model with {gamma}-cascade and width-fluctuations. Advanced treatment of the fission channel takes into account transmission through a multiple-humped fission barrier with absorption in the wells. The fission probability is derived in the WKB approximation within the optical model of fission. Several options for nuclear level densities include the EMPIRE-specific approach, which accounts for the effects of the dynamic deformation of a fast rotating nucleus, the classical Gilbert-Cameron approach and pre-calculated tables obtained with a microscopic model based on HFB single-particle level schemes with collective enhancement. A comprehensive library of input parameters covers nuclear masses, optical model parameters, ground state deformations, discrete levels and decay schemes, level densities, fission barriers, moments of inertia and {gamma}-ray strength functions. The results can be converted into ENDF-6

Transformation products and reaction kinetics of fragrances in advanced wastewater treatment with ozone.

PubMed

Janzen, Niklas; Dopp, Elke; Hesse, Julia; Richards, Jessica; Türk, Jochen; Bester, Kai

2011-11-01

The reaction of the fragrance compounds 4,6,6,7,8,8-hexamethyl-1,3,4,7-tetrahydrocyclopenta[g]isochromene (HHCB), 1-(3,5,5,6,8,8-hexamethyl-6,7-dihydronaphthalen-2-yl)ethanone (AHTN), 1-tert-butyl-3,5-dimethyl-2,4,6-trinitrobenzene (musk xylene/MX), 1-(4-tert-butyl-2,6-dimethyl-3,5-dinitrophenyl)ethanone (musk ketone/MK), and 1-(2,3,8,8-tetramethyl-1,3,4,5,6,7-hexahydronaphthalen-2-yl)ethanone (OTNE) with ozone in tap water as well as waste water treatment plant (WWTP) effluents is described. Several transformation products are characterized by means of gas chromatography coupled to mass spectrometry. One transformation product (HHCB-Lactone) was confirmed by means of a true standard. Musk xylene and musk ketone do not react with ozone under the conditions used in this study. AHTN and HHCB reacted slowly to a multitude of transformation products, while OTNE reacted quickly to several stable transformation products. The reaction constants and half lives are used to predict removal efficiencies for full scale reactors. Copyright © 2011 Elsevier Ltd. All rights reserved.

Selenocysteine in Thiol/Disulfide-Like Exchange Reactions

PubMed Central

Marino, Stefano M.

2013-01-01

Abstract Significance: Among trace elements used as cofactors in enzymes, selenium is unique in that it is incorporated into proteins co-translationally in the form of an amino acid, selenocysteine (Sec). Sec differs from cysteine (Cys) by only one atom (selenium versus sulfur), yet this switch dramatically influences important aspects of enzyme reactivity. Recent Advances: The main focus of this review is an updated and critical discussion on how Sec might be used to accelerate thiol/disulfide-like exchange reactions in natural selenoenzymes, compared with their Cys-containing homologs. Critical Issues: We discuss in detail three major aspects associated with thiol/disulfide exchange reactions: (i) nucleophilicity of the attacking thiolate (or selenolate); (ii) electrophilicity of the center sulfur (or selenium) atom; and (iii) stability of the leaving group (sulfur or selenium). In all these cases, we analyze the benefits that selenium might provide in these types of reactions. Future Directions: It is the biological thiol oxidoreductase-like function that benefits from the use of Sec, since Sec functions to chemically accelerate the rate of these reactions. We review various hypotheses that could help explain why Sec is used in enzymes, particularly with regard to competitive chemical advantages provided by the presence of the selenium atom in enzymes. Ultimately, these chemical advantages must be connected to biological functions of Sec. Antioxid. Redox Signal. 18, 1675–1689. PMID:23121622

Meat flavor precursors and factors influencing flavor precursors--A systematic review.

PubMed

Khan, Muhammad Issa; Jo, Cheorun; Tariq, Muhammad Rizwan

2015-12-01

Flavor is the sensory impression sensed by taste and smell buds and is a leading factor determining the meat quality and purchasing decision of the consumer. Meat flavor is characteristic of volatiles produced as a result of reactions of non-volatile components that are induced thermally. The water soluble compounds having low molecular weight and meat lipids are important precursors of cooked meat flavor. The Maillard reaction, lipid oxidation, and vitamin degradation are leading reactions during cooking which develop meat flavor from uncooked meat with little aroma and bloody taste. The pre-slaughter and postmortem factors like animal breed, sex, age, feed, aging and cooking conditions contribute to flavor development of cooked meat. The objective of this review is to highlight the flavor chemistry, meat flavor precursors and factors affecting meat flavor precursors. Copyright © 2015 Elsevier Ltd. All rights reserved.

Photocatalytic degradation of paracetamol: intermediates and total reaction mechanism.

PubMed

Moctezuma, Edgar; Leyva, Elisa; Aguilar, Claudia A; Luna, Raúl A; Montalvo, Carlos

2012-12-01

The advanced oxidation of paracetamol (PAM) promoted by TiO(2)/UV system in aqueous medium was investigated. Monitoring this reaction by HPLC and TOC, it was demonstrated that while oxidation of paracetamol is quite efficient under these conditions, its mineralization is not complete. HPLC indicated the formation of hydroquinone, benzoquinone, p-aminophenol and p-nitrophenol in the reaction mixtures. Further evidence of p-nitrophenol formation was obtained following the reaction by UV-vis spectroscopy. Continuous monitoring by IR spectroscopy demonstrated the breaking of the aromatic amide present in PAM and subsequent formation of several aromatic intermediate compounds such as p-aminophenol and p-nitrophenol. These aromatic compounds were eventually converted into trans-unsaturated carboxylic acids. Based on these experimental results, an alternative deacylation mechanism for the photocatalytic oxidation of paracetamol is proposed. Our studies also demonstrated IR spectroscopy to be a useful technique to investigate oxidative mechanisms of pharmaceutical compounds. Copyright © 2012 Elsevier B.V. All rights reserved.

From ab Initio Potential Energy Surfaces to State-Resolved Reactivities: X + H 2O ↔ HX + OH [X = F, Cl, and O( 3P)] Reactions

DOE PAGES

Li, Jun; Jiang, Bin; Song, Hongwei; ...

2015-04-17

Here, we survey the recent advances in theoretical understanding of quantum state resolved dynamics, using the title reactions as examples. It is shown that the progress was made possible by major developments in two areas. First, an accurate analytical representation of many high-level ab initio points over a large configuration space can now be made with high fidelity and the necessary permutation symmetry. The resulting full-dimensional global potential energy surfaces enable dynamical calculations using either quasi-classical trajectory or more importantly quantum mechanical methods. The second advance is the development of accurate and efficient quantum dynamical methods, which are necessary formore » providing a reliable treatment of quantum effects in reaction dynamics such as tunneling, resonances, and zero-point energy. The powerful combination of the two advances has allowed us to achieve a quantitatively accurate characterization of the reaction dynamics, which unveiled rich dynamical features such as steric steering, strong mode specificity, and bond selectivity. The dependence of reactivity on reactant modes can be rationalized by the recently proposed sudden vector projection model, which attributes the mode specificity and bond selectivity to the coupling of reactant modes with the reaction coordinate at the relevant transition state. The deeper insights provided by these theoretical studies have advanced our understanding of reaction dynamics to a new level.« less

Reaction-diffusion controlled growth of complex structures

NASA Astrophysics Data System (ADS)

Noorduin, Willem; Mahadevan, L.; Aizenberg, Joanna

2013-03-01

Understanding how the emergence of complex forms and shapes in biominerals came about is both of fundamental and practical interest. Although biomineralization processes and organization strategies to give higher order architectures have been studied extensively, synthetic approaches to mimic these self-assembled structures are highly complex and have been difficult to emulate, let alone replicate. The emergence of solution patterns has been found in reaction-diffusion systems such as Turing patterns and the BZ reaction. Intrigued by this spontaneous formation of complexity we explored if similar processes can lead to patterns in the solid state. We here identify a reaction-diffusion system in which the shape of the solidified products is a direct readout of the environmental conditions. Based on insights in the underlying mechanism, we developed a toolbox of engineering strategies to deterministically sculpt patterns and shapes, and combine different morphologies to create a landscape of hierarchical multi scale-complex tectonic architectures with unprecedented levels of complexity. These findings may hold profound implications for understanding, mimicking and ultimately expanding upon nature's morphogenesis strategies, allowing the synthesis of advanced highly complex microscale materials and devices. WLN acknowledges the Netherlands Organization for Scientific Research for financial support

Comparative evaluation of atom mapping algorithms for balanced metabolic reactions: application to Recon 3D

DOE PAGES

Preciat Gonzalez, German A.; El Assal, Lemmer R. P.; Noronha, Alberto; ...

2017-06-14

The mechanism of each chemical reaction in a metabolic network can be represented as a set of atom mappings, each of which relates an atom in a substrate metabolite to an atom of the same element in a product metabolite. Genome-scale metabolic network reconstructions typically represent biochemistry at the level of reaction stoichiometry. However, a more detailed representation at the underlying level of atom mappings opens the possibility for a broader range of biological, biomedical and biotechnological applications than with stoichiometry alone. Complete manual acquisition of atom mapping data for a genome-scale metabolic network is a laborious process. However, manymore » algorithms exist to predict atom mappings. How do their predictions compare to each other and to manually curated atom mappings? For more than four thousand metabolic reactions in the latest human metabolic reconstruction, Recon 3D, we compared the atom mappings predicted by six atom mapping algorithms. We also compared these predictions to those obtained by manual curation of atom mappings for over five hundred reactions distributed among all top level Enzyme Commission number classes. Five of the evaluated algorithms had similarly high prediction accuracy of over 91% when compared to manually curated atom mapped reactions. On average, the accuracy of the prediction was highest for reactions catalysed by oxidoreductases and lowest for reactions catalysed by ligases. In addition to prediction accuracy, the algorithms were evaluated on their accessibility, their advanced features, such as the ability to identify equivalent atoms, and their ability to map hydrogen atoms. In addition to prediction accuracy, we found that software accessibility and advanced features were fundamental to the selection of an atom mapping algorithm in practice.« less

Comparative evaluation of atom mapping algorithms for balanced metabolic reactions: application to Recon 3D

DOE Office of Scientific and Technical Information (OSTI.GOV)

Preciat Gonzalez, German A.; El Assal, Lemmer R. P.; Noronha, Alberto

The mechanism of each chemical reaction in a metabolic network can be represented as a set of atom mappings, each of which relates an atom in a substrate metabolite to an atom of the same element in a product metabolite. Genome-scale metabolic network reconstructions typically represent biochemistry at the level of reaction stoichiometry. However, a more detailed representation at the underlying level of atom mappings opens the possibility for a broader range of biological, biomedical and biotechnological applications than with stoichiometry alone. Complete manual acquisition of atom mapping data for a genome-scale metabolic network is a laborious process. However, manymore » algorithms exist to predict atom mappings. How do their predictions compare to each other and to manually curated atom mappings? For more than four thousand metabolic reactions in the latest human metabolic reconstruction, Recon 3D, we compared the atom mappings predicted by six atom mapping algorithms. We also compared these predictions to those obtained by manual curation of atom mappings for over five hundred reactions distributed among all top level Enzyme Commission number classes. Five of the evaluated algorithms had similarly high prediction accuracy of over 91% when compared to manually curated atom mapped reactions. On average, the accuracy of the prediction was highest for reactions catalysed by oxidoreductases and lowest for reactions catalysed by ligases. In addition to prediction accuracy, the algorithms were evaluated on their accessibility, their advanced features, such as the ability to identify equivalent atoms, and their ability to map hydrogen atoms. In addition to prediction accuracy, we found that software accessibility and advanced features were fundamental to the selection of an atom mapping algorithm in practice.« less

Comparative evaluation of atom mapping algorithms for balanced metabolic reactions: application to Recon 3D.

PubMed

Preciat Gonzalez, German A; El Assal, Lemmer R P; Noronha, Alberto; Thiele, Ines; Haraldsdóttir, Hulda S; Fleming, Ronan M T

2017-06-14

The mechanism of each chemical reaction in a metabolic network can be represented as a set of atom mappings, each of which relates an atom in a substrate metabolite to an atom of the same element in a product metabolite. Genome-scale metabolic network reconstructions typically represent biochemistry at the level of reaction stoichiometry. However, a more detailed representation at the underlying level of atom mappings opens the possibility for a broader range of biological, biomedical and biotechnological applications than with stoichiometry alone. Complete manual acquisition of atom mapping data for a genome-scale metabolic network is a laborious process. However, many algorithms exist to predict atom mappings. How do their predictions compare to each other and to manually curated atom mappings? For more than four thousand metabolic reactions in the latest human metabolic reconstruction, Recon 3D, we compared the atom mappings predicted by six atom mapping algorithms. We also compared these predictions to those obtained by manual curation of atom mappings for over five hundred reactions distributed among all top level Enzyme Commission number classes. Five of the evaluated algorithms had similarly high prediction accuracy of over 91% when compared to manually curated atom mapped reactions. On average, the accuracy of the prediction was highest for reactions catalysed by oxidoreductases and lowest for reactions catalysed by ligases. In addition to prediction accuracy, the algorithms were evaluated on their accessibility, their advanced features, such as the ability to identify equivalent atoms, and their ability to map hydrogen atoms. In addition to prediction accuracy, we found that software accessibility and advanced features were fundamental to the selection of an atom mapping algorithm in practice.

Optimization of β-cyclodextrin-based extraction of antioxidant and anti-browning activities from thyme leaves by response surface methodology.

PubMed

Favre, Leonardo Cristian; Dos Santos, Cristina; López-Fernández, María Paula; Mazzobre, María Florencia; Buera, María Del Pilar

2018-11-01

Thyme (Thymus vulgaris) has been demonstrated to extend the shelf-life of food products, being also a potential source of bioactive compounds. The aim of this research was to optimize the ultrasound assisted extraction employing β-cyclodextrin aqueous solutions as no-contaminant technology and Response Surface Methodology to obtain thyme extracts with the maximum antioxidant capacity. The optimal extraction conditions were: a solution of β-ciclodextrin 15 mM, an ultrasonic treatment time of 5.9 min at a temperature of 36.6 °C. They resulted in an extract with a polyphenolic content of 189.3 mg GAE/mL, an antioxidant activity (DPPH) of 14.8 mg GAE/mL, and ferric reducing/antioxidant power (FRAP) of 3.3 mg GAE/mL. Interestingly, the extract demonstrated to inhibit the production of Maillard browning products and can be considered a potential antiglycant agent. The obtained data is important for developing eco-friendly technologies in order to obtain natural antioxidant extracts with a potential inhibitory capacity of Maillard glycation reaction. Copyright © 2018 Elsevier Ltd. All rights reserved.

Small angle scattering from protein/sugar conjugates

NASA Astrophysics Data System (ADS)

Jackson, Andrew; White, John

2006-11-01

The Maillard reaction between free amine groups on proteins and sugars is well known. We have examined the effect of the reaction of the casein group of milk proteins with sugars on their nanoscale structure and aggregation. The small angle neutron scattering from beta casein and sodium caseinate and their sugar conjugates have been studied as a function of solution concentration. At high conjugate concentration (greater than ca. 5 mg/ml) the addition of sugar reduces supra-micellar aggregation of the protein whilst at lower concentration, where the protein is expected to be deaggregated already, little effect is seen. Guinier analysis of the scattering data show a radius of gyration of around 75 A˚ for beta casein in solution and around 80 A˚ for the sucrose conjugate.

Advances in targeted proteomics and applications to biomedical research

PubMed Central

Shi, Tujin; Song, Ehwang; Nie, Song; Rodland, Karin D.; Liu, Tao; Qian, Wei-Jun; Smith, Richard D.

2016-01-01

Targeted proteomics technique has emerged as a powerful protein quantification tool in systems biology, biomedical research, and increasing for clinical applications. The most widely used targeted proteomics approach, selected reaction monitoring (SRM), also known as multiple reaction monitoring (MRM), can be used for quantification of cellular signaling networks and preclinical verification of candidate protein biomarkers. As an extension to our previous review on advances in SRM sensitivity herein we review recent advances in the method and technology for further enhancing SRM sensitivity (from 2012 to present), and highlighting its broad biomedical applications in human bodily fluids, tissue and cell lines. Furthermore, we also review two recently introduced targeted proteomics approaches, parallel reaction monitoring (PRM) and data-independent acquisition (DIA) with targeted data extraction on fast scanning high-resolution accurate-mass (HR/AM) instruments. Such HR/AM targeted quantification with monitoring all target product ions addresses SRM limitations effectively in specificity and multiplexing; whereas when compared to SRM, PRM and DIA are still in the infancy with a limited number of applications. Thus, for HR/AM targeted quantification we focus our discussion on method development, data processing and analysis, and its advantages and limitations in targeted proteomics. Finally, general perspectives on the potential of achieving both high sensitivity and high sample throughput for large-scale quantification of hundreds of target proteins are discussed. PMID:27302376

Technical Performance and Economic Evaluation of Evaporative and Membrane-Based Concentration for Biomass-Derived Sugars

DOE Office of Scientific and Technical Information (OSTI.GOV)

Sievers, David A.; Stickel, Jonathan J.; Grundl, Nicholas J.

Several conversion pathways of lignocellulosic biomass to advanced biofuels require or benefit from using concentrated sugar syrups of 600 g/L or greater. And while concentration may seem straightforward, thermal sugar degradation and energy efficiency remain major concerns. This study evaluated the trade-offs in product recovery, energy consumption, and economics between evaporative and membrane-based concentration methods. The degradation kinetics of xylose and glucose were characterized and applied to an evaporator process simulation. Though significant sugar loss was predicted for certain scenarios due to the Maillard reaction, industrially common falling-film plate evaporators offer short residence times (<5 min) and are expected tomore » limit sugar losses. Membrane concentration experiments characterized flux and sugar rejection, but diminished flux occurred at >100 g/L. A second step using evaporation is necessary to achieve target concentrations. Techno-economic process model simulations evaluated the overall economics of concentrating a 35 g/L sugar stream to 600 g/L in a full-scale biorefinery. A two-step approach of preconcentrating using membranes and finishing with an evaporator consumed less energy than evaporation alone but was more expensive because of high capital expenses of the membrane units.« less

Technical Performance and Economic Evaluation of Evaporative and Membrane-Based Concentration for Biomass-Derived Sugars

DOE PAGES

Sievers, David A.; Stickel, Jonathan J.; Grundl, Nicholas J.; ...

2017-09-18

Several conversion pathways of lignocellulosic biomass to advanced biofuels require or benefit from using concentrated sugar syrups of 600 g/L or greater. And while concentration may seem straightforward, thermal sugar degradation and energy efficiency remain major concerns. This study evaluated the trade-offs in product recovery, energy consumption, and economics between evaporative and membrane-based concentration methods. The degradation kinetics of xylose and glucose were characterized and applied to an evaporator process simulation. Though significant sugar loss was predicted for certain scenarios due to the Maillard reaction, industrially common falling-film plate evaporators offer short residence times (<5 min) and are expected tomore » limit sugar losses. Membrane concentration experiments characterized flux and sugar rejection, but diminished flux occurred at >100 g/L. A second step using evaporation is necessary to achieve target concentrations. Techno-economic process model simulations evaluated the overall economics of concentrating a 35 g/L sugar stream to 600 g/L in a full-scale biorefinery. A two-step approach of preconcentrating using membranes and finishing with an evaporator consumed less energy than evaporation alone but was more expensive because of high capital expenses of the membrane units.« less

The In Situ Enzymatic Screening (ISES) Approach to Reaction Discovery and Catalyst Identification.

PubMed

Swyka, Robert A; Berkowitz, David B

2017-12-14

The importance of discovering new chemical transformations and/or optimizing catalytic combinations has led to a flurry of activity in reaction screening. The in situ enzymatic screening (ISES) approach described here utilizes biological tools (enzymes/cofactors) to advance chemistry. The protocol interfaces an organic reaction layer with an adjacent aqueous layer containing reporting enzymes that act upon the organic reaction product, giving rise to a spectroscopic signal. ISES allows the experimentalist to rapidly glean information on the relative rates of a set of parallel organic/organometallic reactions under investigation, without the need to quench the reactions or draw aliquots. In certain cases, the real-time enzymatic readout also provides information on sense and magnitude of enantioselectivity and substrate specificity. This article contains protocols for single-well (relative rate) and double-well (relative rate/enantiomeric excess) ISES, in addition to a colorimetric ISES protocol and a miniaturized double-well procedure. © 2017 by John Wiley & Sons, Inc. Copyright © 2017 John Wiley & Sons, Inc.

Temperature Influence on Acetyllysine Interaction with Glucose in Model Systems due to Maillard Reaction

DTIC Science & Technology

1992-01-01

present experiments have per- Dry foods (such as milk chocolate, yogurt products , dried fruits, mitted us to compute an E, of 44 kcal/mol from zero order...Interpretation of the data was complicated by del et at., 1955; Hsu and Fennema, 1989; Kim et al., 1981; the - presence of two reactive groups, the alpha and the...6.4 acetate buffer in 6% (v/v) acetonitrlle-water) - Eluent B (60% incubation, the withdrawal times were 0, 4, 8, Z4, 72, 144, 288, 576, (v/v

Recent Advances in Nickel Catalysis

PubMed Central

Tasker, Sarah Z.; Standley, Eric A.; Jamison, Timothy F.

2015-01-01

Preface The field of nickel catalysis has made tremendous advances in the past decade. There are several key properties of nickel that have allowed for a broad range of innovative reaction development, such as facile oxidative addition and ready access to multiple oxidation states. In recent years, these properties have been increasingly understood and leveraged to perform transformations long considered exceptionally challenging. Herein, we discuss some of the most recent and significant developments in homogeneous nickel catalysis with an emphasis on both synthetic outcome and mechanism. PMID:24828188

Fluorogenic reaction-based prodrug conjugates as targeted cancer theranostics.

PubMed

Lee, Min Hee; Sharma, Amit; Chang, Min Jung; Lee, Jinju; Son, Subin; Sessler, Jonathan L; Kang, Chulhun; Kim, Jong Seung

2018-01-02

Theranostic systems are receiving ever-increasing attention due to their potential therapeutic utility, imaging enhancement capability, and promise for advancing the field of personalized medicine, particularly as it relates to the diagnosis, staging, and treatment of cancer. In this Tutorial Review, we provide an introduction to the concepts of theranostic drug delivery effected via use of conjugates that are able to target cancer cells selectively, provide cytotoxic chemotherapeutics, and produce readily monitored imaging signals in vitro and in vivo. The underlying design concepts, requiring the synthesis of conjugates composed of imaging reporters, masked chemotherapeutic drugs, cleavable linkers, and cancer targeting ligands, are discussed. Particular emphasis is placed on highlighting the potential benefits of fluorogenic reaction-based targeted systems that are activated for both imaging and therapy by cellular entities, e.g., thiols, reactive oxygen species and enzymes, which are present at relatively elevated levels in tumour environments, physiological characteristics of cancer, e.g., hypoxia and acidic pH. Also discussed are systems activated by an external stimulus, such as light. The work summarized in this Tutorial Review will help define the role fluorogenic reaction-based, cancer-targeting theranostics may have in advancing drug discovery efforts, as well as improving our understanding of cellular uptake and drug release mechanisms.

Bioinspired Electrocatalysis of Oxygen Reduction Reaction in Fuel Cells Using Molecular Catalysts.

PubMed

Zion, Noam; Friedman, Ariel; Levy, Naomi; Elbaz, Lior

2018-04-23

One of the most important chemical reactions for renewable energy technologies such as fuel cells and metal-air batteries today is oxygen reduction. Due to the relatively sluggish reaction kinetics, catalysts are necessary to generate high power output. The most common catalyst for this reaction is platinum, but its scarcity and derived high price have raised the search for abundant nonprecious metal catalysts. Inspired from enzymatic processes which are known to catalyze oxygen reduction reaction efficiently, employing transition metal complexes as their catalytic centers, many are working on the development of bioinspired and biomimetic catalysts of this class. This research news article gives a glimpse of the recent progress on the development of bioinspired molecular catalyst for oxygen reduction, highlighting the importance of the molecular structure of the catalysts, from advancements in porphyrins and phthalocyanines to the most recent work on corroles, and 3D networks such as metal-organic frameworks and polymeric networks, all with nonpyrolyzed, well-defined molecular catalysts for oxygen reduction reaction. © 2018 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.

Identifying genomic and developmental causes of adverse drug reactions in children

PubMed Central

Becker, Mara L; Leeder, J Steven

2011-01-01

Adverse drug reactions are a concern for all clinicians who utilize medications to treat adults and children; however, the frequency of adult and pediatric adverse drug reactions is likely to be under-reported. In this age of genomics and personalized medicine, identifying genetic variation that results in differences in drug biotransformation and response has contributed to significant advances in the utilization of several commonly used medications in adults. In order to better understand the variability of drug response in children however, we must not only consider differences in genotype, but also variation in gene expression during growth and development, namely ontogeny. In this article, recommendations for systematically approaching pharmacogenomic studies in children are discussed, and several examples of studies that investigate the genomic and developmental contribution to adverse drug reactions in children are reviewed. PMID:21121777

Identification and quantification of major maillard cross-links in human serum albumin and lens protein. Evidence for glucosepane as the dominant compound.

PubMed

Biemel, Klaus M; Friedl, D Alexander; Lederer, Markus O

2002-07-12

Glycation reactions leading to protein modifications (advanced glycation end products) contribute to various pathologies associated with the general aging process and long term complications of diabetes. However, only few relevant compounds have so far been detected in vivo. We now report on the first unequivocal identification of the lysine-arginine cross-links glucosepane 5, DOGDIC 6, MODIC 7, and GODIC 8 in human material. For their accurate quantification by coupled liquid chromatography-electrospray ionization mass spectrometry, (13)C-labeled reference compounds were synthesized independently. Compounds 5-8 are formed via the alpha-dicarbonyl compounds N(6)-(2,3-dihydroxy-5,6-dioxohexyl)-l-lysinate (1a,b), 3-deoxyglucosone (), methylglyoxal (), and glyoxal (), respectively. The protein-bound dideoxyosone 1a,b seems to be of prime significance for cross-linking because it presumably is not detoxified by mammalian enzymes as readily as 2-4. Hence, the follow-up product glucosepane 5 was found to be the dominant compound. Up to 42.3 pmol of 5/mg of protein was identified in human serum albumin of diabetics; the level of 5 correlates markedly with the glycated hemoglobin HbA(1c). In the water-insoluble fraction of lens proteins from normoglycemics, concentration of 5 ranges between 132.3 and 241.7 pmol/mg. The advanced glycoxidation end product GODIC 8 is elevated significantly in brunescent lenses, indicating enhanced oxidative stress in this material. Compounds 5-8 thus appear predestined as markers for pathophysiological processes.

Sonophotocatalysis in advanced oxidation process: a short review.

PubMed

Joseph, Collin G; Li Puma, Gianluca; Bono, Awang; Krishnaiah, Duduku

2009-06-01

Sonophotocatalysis involves the use of a combination of ultrasonic sound waves, ultraviolet radiation and a semiconductor photocatalyst to enhance a chemical reaction by the formation of free radicals in aqueous systems. Researchers have used sonophotocatalysis in a variety of investigations i.e. from water decontamination to direct pollutant degradation. This degradation process provides an excellent opportunity to reduce reaction time and the amount of reagents used without the need for extreme physical conditions. Given its advantages, the sonophotocatalysis process has a futuristic application from an engineering and fundamental aspect in commercial applications. A detailed search of published reports was done and analyzed in this paper with respect to sonication, photocatalysis and advanced oxidation processes.

Molecular Controls of the Oxygenation and Redox Reactions of Hemoglobin

PubMed Central

Henkens, Robert; Alayash, Abdu I.; Banerjee, Sambuddha; Crumbliss, Alvin L.

2013-01-01

Abstract Significance: The broad classes of O2-binding proteins known as hemoglobins (Hbs) carry out oxygenation and redox functions that allow organisms with significantly different physiological demands to exist in a wide range of environments. This is aided by allosteric controls that modulate the protein's redox reactions as well as its O2-binding functions. Recent Advances: The controls of Hb's redox reactions can differ appreciably from the molecular controls for Hb oxygenation and come into play in elegant mechanisms for dealing with nitrosative stress, in the malarial resistance conferred by sickle cell Hb, and in the as-yet unsuccessful designs for safe and effective blood substitutes. Critical Issues: An important basic principle in consideration of Hb's redox reactions is the distinction between kinetic and thermodynamic reaction control. Clarification of these modes of control is critical to gaining an increased understanding of Hb-mediated oxidative processes and oxidative toxicity in vivo. Future Directions: This review addresses emerging concepts and some unresolved questions regarding the interplay between the oxygenation and oxidation reactions of structurally diverse Hbs, both within red blood cells and under acellular conditions. Developing methods that control Hb-mediated oxidative toxicity will be critical to the future development of Hb-based blood substitutes. Antioxid. Redox Signal. 18, 2298–2313. PMID:23198874

The health and technological implications of a better control of neoformed contaminants by the food industry.

PubMed

Birlouez-Aragon, I; Morales, F; Fogliano, V; Pain, J-P

2010-06-01

The recent discovery of the presence of variable amounts of the carcinogenic compound acrylamide in a wide range of severely heat-treated food products, such as fried potatoes, biscuits, bread and coffee or malt, as a result of the heat process, has induced an important research in the area of the Maillard reaction in food. The interaction between a specific food composition and the heat process applied results in the development of complex oxidation and glycation reactions, which give rise to a mixture of flavoured compounds and possible neoformed contaminants (NFC). Recommendations by the European Commission aim at monitoring the content of major NFC, such as acrylamide and furan, in a list of food products commercialized in Europe. On the other hand, the Commission for European Normalization (CEN) has created recently a new workgroup (WG13) responsible for normalization of analytical method for NFC assessment. The European collective research ICARE was carried out to identify the possible health consequences of the ingestion of heat-treated products, characterize the reaction kinetics leading to NFC and evaluate some mitigation procedures proposed by the CIAA toolbox, and finally develop a simple, rapid and non destructive control method based on fluorescence acquisition on the crushed food products and chemometric analysis of the spectral information. This paper summarizes the objectives and essential results obtained in the scope of the project, highlighting the need for evaluating the distribution of NFC in food products commercialized in Europe, as well as the impact of the food formula/recipe and process on Maillard derived NFC food levels. The potential of the Fluoralys sensor regarding its ability to control food contamination with NFC is presented. A decrease in NFC concentration of heat processed food should allow significantly limiting the exposure of populations to NFC and consequently the potential related health risk. (c) 2009 Elsevier Masson SAS

Protein Hydrolysates as Hypoallergenic, Flavors and Palatants for Companion Animals

NASA Astrophysics Data System (ADS)

Nagodawithana, Tilak W.; Nelles, Lynn; Trivedi, Nayan B.

Early civilizations have relied upon their good sense and experience to develop and improve their food quality. The discovery of soy sauce centuries ago can now be considered one of the earliest protein hydrolysates made by man to improve palatability of foods. Now, it is well known that such savory systems are not just sources for enjoyment but complex semiotic systems that direct the humans to satisfy the body's protein need for their sustenance. Recent developments have resulted in a wide range of cost effective savory flavorings, the best known of which are autolyzed yeast extracts and hydrolyzed vegetable proteins. New technologies have helped researchers to improve the savory characteristics of yeast extracts through the application of Maillard reaction and by generating specific flavor enhancers through the use of enzymes. An interesting parallel exists in the pet food industry, where a similar approach is taken in using animal protein hydrolysates to create palatability enhancers via Maillard reaction scheme. Protein hydrolysates are also utilized extensively as a source of nutrition to the elderly, young children and immuno-compromised patient population. These hydrolysates have an added advantage in having peptides small enough to avoid any chance of an allergenic reaction which sometimes occur with the consumption of larger sized peptides or proteins. Accordingly, protein hydrolysates are required to have an average molecular weight distribution in the range 800-1,500 Da to make them non-allergenic. The technical challenge for scientists involved in food and feed manufacture is to use an appropriate combination of enzymes within the existing economic constraints and other physical factors/limitations, such as heat, pH, and time, to create highly palatable, yet still nutritious and hypoallergenic food formulations.

Some concepts of the advanced mass spectrometry at the COMBAS magnetic separator of nuclear reaction products

NASA Astrophysics Data System (ADS)

Artukh, A. G.; Tarantin, N. I.

Proposed is an in-flight measurement method of recoil nuclei masses with the help of a Penning trap located behind the COMBAS magnetic separator for nuclear reaction products. The method is based on the following operations: (i) Accepting the recoil nuclear reaction products by the magnetic separator and decreasing their kinetic energy by degraders. (ii) In-flight transportation of the retarded nuclei into the magnetic field of the Penning trap's solenoid and transforming their remaining longitudinal momentum into orbital rotation by the fringing magnetic field of the solenoid. (iii) Cooling the orbital rotation of the ions by the high-frequency azimuthal electric field of the Penning trap's electric hyperboloid.

Treatment of statin compounds by advanced oxidation processes: Kinetic considerations and destruction mechanisms

NASA Astrophysics Data System (ADS)

Razavi, Behnaz; Song, Weihua; Santoke, Hanoz; Cooper, William J.

2011-03-01

This study examined the use of advanced oxidation/reduction processes (AO/RPs) for the destruction of cholesterol lowering statin pharmaceuticals. AO/RPs which utilize the oxidizing hydroxyl radical ( rad OH) and reducing aqueous electron (e -aq), to degrade chemical contaminants are alternatives to traditional water treatment methods, and are alternatives as water reuse becomes more generally implemented. Four major statin pharmaceuticals, fluvastatin, lovastatin, pravastatin and simvastatin, were studied, and the absolute bimolecular reaction rate constants with rad OH determined, (6.96±0.16)×10 9, (2.92±0.06)×10 9, (4.16±0.13)×10 9, and (3.13±0.15)×10 9 M -1 s -1, and for e -aq (2.31±0.06)×10 9, (0.45±0.01)×10 9, (1.26±0.01)×10 9, and (0.69±0.02)×10 9 M -1 s -1, respectively. To provide additional information on the radicals formed upon oxidation, transient spectra were measured and the overall reaction efficiency determined. Radical-based destruction mechanisms for destruction of the statins are proposed based on the LC-MS determination of the stable reaction by-products formed using 137Cs γ-irradiation of statin solutions. Knowing the reaction rates, reaction efficiencies and destruction mechanisms of these compounds is essential for the consideration of the use of advanced oxidation/reduction processes for the destruction of statins in aqueous systems.

Recent Advances in Electrochemical Immunosensors

PubMed Central

Piro, Benoît; Reisberg, Steeve

2017-01-01

Immunosensors have experienced a very significant growth in recent years, driven by the need for fast, sensitive, portable and easy-to-use devices to detect biomarkers for clinical diagnosis or to monitor organic pollutants in natural or industrial environments. Advances in the field of signal amplification using enzymatic reactions, nanomaterials such as carbon nanotubes, graphene and graphene derivatives, metallic nanoparticles (gold, silver, various oxides or metal complexes), or magnetic beads show how it is possible to improve collection, binding or transduction performances and reach the requirements for realistic clinical diagnostic or environmental control. This review presents these most recent advances; it focuses first on classical electrode substrates, then moves to carbon-based nanostructured ones including carbon nanotubes, graphene and other carbon materials, metal or metal-oxide nanoparticles, magnetic nanoparticles, dendrimers and, to finish, explore the use of ionic liquids. Analytical performances are systematically covered and compared, depending on the detection principle, but also from a chronological perspective, from 2012 to 2016 and early 2017. PMID:28387718