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1.
Food Chem ; 312: 126085, 2020 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-31896460

RESUMO

The effects of hydroxycinnamic acids such as cinnamic acid (CNA), p-coumaric acid(CMA), caffeic acid (CFA), and chlorogenic acid (CGA) on the reduction of furan in canned-coffee model systems (CCMS) containing α-dicarbonyls [glyoxal (GO) or methylglyoxal (MGO)] were investigated. The concentration of furan in CCMS containing GO, which was 59.76 µg/L, was reduced by the addition of CFA and CGA to 48.31 µg/L and 41.38 µg/L, respectively; similarly, the furan concentration in model system containing MGO was 45.79 µg/L, and this decreased to 35.41 µg/L (by CFA) and 32.65 µg/L (by CGA), respectively. In addition, the effects of hydroxycinnamic acids on the trapping of GO and MGO were determined. CFA and CGA greatly reduced the concentration of GO to 303.51 µg/L and 267.80 µg/L, respectively (compared to 515.79 µg/L in the control), whereas that of MGO was decreased to 207.01 µg/L and 219.14 µg/L (compared to 417.14 µg/L in the control). The trapping of α-dicarbonyls such as GO and MGO by CFA and CGA could be closely related to furan reduction in CCMS.


Assuntos
Ácidos Cumáricos/química , Furanos/química , Aldeído Pirúvico/química , Ácido Clorogênico/química , Café/química , Glioxal/química
2.
Food Chem ; 311: 125999, 2020 May 01.
Artigo em Inglês | MEDLINE | ID: mdl-31864185

RESUMO

A method based on solid-phase extraction (SPE) coupled with high-performance liquid chromatography (HPLC) was developed to determine the content of 4-chlorophenoxy acetic acid (PCPA), naphthylacetic acid (NAA) and 2,4-dichlorophenoxyacetic acid (2,4-D) in green bell peppers. A molecularly imprinted 3-aminophenol-glyoxal-urea resin (MIAGUR) was first synthesized as a specific SPE adsorbent, which exhibited special selectivity and multiple adsorption interactions including hydrogen bonding and π-π interactions. The quantities of PCPA, NAA and 2,4-D in green bell peppers from 20 samples scattered throughout Baoding city (Hebei province, China) were determined using the proposed method. The results suggested that the use of PCPA, NAA and 2,4-D in green bell peppers from Baoding's markets is almost in fair. Moreover, MIAGUR-SPE-HPLC is suitable for the specific simultaneous monitoring of PCPA, NAA, and 2,4-D in green bell peppers and has potential applications in determination of PCPA, NAA, and 2,4-D of other plant products.


Assuntos
Capsicum/metabolismo , Impressão Molecular , Reguladores de Crescimento de Planta/análise , Ureia/química , Aminofenóis/química , Capsicum/química , Cromatografia Líquida de Alta Pressão/métodos , Glioxal/química , Interações Hidrofóbicas e Hidrofílicas , Reguladores de Crescimento de Planta/isolamento & purificação , Extração em Fase Sólida
3.
Food Chem ; 309: 125708, 2020 Mar 30.
Artigo em Inglês | MEDLINE | ID: mdl-31683151

RESUMO

Herein, corn silk extract and its flavonoids were used to inhibit the formation of Nε-carboxymethyllysine (CML) in a casein glucose-fatty acid model system. Under these optimum extraction conditions, nine major flavonoids were identified and quantified by HPLC-MS/MS. The percent inhibition of CML formation by corn silk extract was 76.57%. The inhibitory mechanism of corn silk extract toward CML formation was further investigated by examining the trapping of glyoxal/methyl glyoxal by the major flavonoids (5 mM) using HPLC-ESI-MS, and mono-, di-, and tri-adducts were found for some flavonoid compounds. The antioxidant activity of the corn silk extract was evaluated by the DPPH and ABTS assays. The scavenging activity of the corn silk extract for DPPH and ABTS was 84.38% and 89.11%, respectively. The results suggested that corn silk extract inhibited CML formation through glyoxal/methyl glyoxal scavenging or by its antioxidant activity attributed to its flavonoid content.


Assuntos
Flavonoides/química , Glioxal/química , Lisina/análogos & derivados , Modelos Biológicos , Zea mays/química , Antioxidantes/química , Caseínas/química , Cromatografia Líquida de Alta Pressão , Ácidos Graxos/química , Flavonoides/análise , Glucose/química , Lisina/química , Lisina/metabolismo , Extratos Vegetais/química , Seda/química , Espectrometria de Massas em Tandem , Zea mays/metabolismo
4.
J Agric Food Chem ; 67(43): 12094-12104, 2019 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-31566978

RESUMO

A large portion of Maillard reaction products (MRPs) cannot be absorbed in the upper gut and therefore may be further decomposed and utilized by colonic microbiota (CM). This work reported the stability of UV-absorbent MRPs, fluorescent MRPs and peptide-bound N(ε)-(carboxymethyl)-lysine (CML) in high molecular weight (HMW, >10 kDa), medium molecular weight (MMW, 1-10 kDa), and low molecular weight (LMW, <1 kDa) gastrointestinal digests of glyoxal-glycated casein in the presence of CM. Fluorescent MRPs showed high stability, whereas UV-absorbent MRPs may be partially decomposed. A higher depletion rate of CML was found in the LMW fraction (38.7%) than in the MMW (21.7%) and HMW (9.6%) fractions. The 16S rRNA sequencing results revealed both beneficial and detrimental changes in CM composition induced by the glycated fractions. Generation of short-chain and branched-chain fatty acids in fermentation solutions with glycated fractions was significantly suppressed compared with that in fermentation solution with unglycated digests. This work revealed the possible interplay between peptide-bound MRPs and CM.


Assuntos
Caseínas/metabolismo , Colo/microbiologia , Microbioma Gastrointestinal , Produtos Finais de Glicação Avançada/metabolismo , Glioxal/metabolismo , Peptídeos/metabolismo , Adulto , Bactérias/classificação , Bactérias/genética , Bactérias/isolamento & purificação , Bactérias/metabolismo , Caseínas/química , Colo/metabolismo , Ácidos Graxos Voláteis/metabolismo , Feminino , Produtos Finais de Glicação Avançada/química , Glioxal/química , Humanos , Reação de Maillard , Masculino , Peptídeos/química , Adulto Jovem
5.
J Agric Food Chem ; 67(39): 10921-10929, 2019 Oct 02.
Artigo em Inglês | MEDLINE | ID: mdl-31496242

RESUMO

Free amino residues react with α-dicarbonyl compounds (DCs) contributing to the formation of advanced glycation end products (AGEs). Phenolic compounds can scavenge DCs, thus controlling the dietary carbonyl load. This study showed that high-molecular weight cocoa melanoidins (HMW-COM), HMW bread melanoidins (HMW-BM), and especially HMW coffee melanoidins (HMW-CM) are effective DC scavengers. HMW-CM (1 mg/mL) scavenged more than 40% DCs within 2 h under simulated physiological conditions, suggesting some physiological relevance. Partial acid hydrolysis of HMW-CM decreased the dicarbonyl trapping capacity, demonstrating that the ability to react with glyoxal, methylglyoxal (MGO), and diacetyl was mainly because of polyphenols bound to macromolecules. Caffeic acid (CA) and 3-caffeoylquinic acid showed a DC-scavenging kinetic profile similar to that of HMW-CM, while mass spectrometry data confirmed that hydroxyalkylation and aromatic substitution reactions led to the formation of a stable adduct between CA and MGO. These findings corroborated the idea that antioxidant-rich indigestible materials could limit carbonyl stress and AGE formation across the gastrointestinal tract.


Assuntos
Pão/análise , Cacau/química , Café/química , Diacetil/química , Depuradores de Radicais Livres/química , Extratos Vegetais/química , Polímeros/química , Cacau/metabolismo , Café/metabolismo , Diacetil/metabolismo , Depuradores de Radicais Livres/metabolismo , Trato Gastrointestinal/metabolismo , Glioxal/química , Humanos , Modelos Biológicos , Extratos Vegetais/metabolismo , Polímeros/metabolismo , Aldeído Pirúvico/química , Aldeído Pirúvico/metabolismo
6.
Curr Pharm Biotechnol ; 20(12): 1028-1036, 2019.
Artigo em Inglês | MEDLINE | ID: mdl-31364512

RESUMO

BACKGROUND & OBJECTIVE: The present study was aimed at characterizing the conformational alterations induced in human transferrin, the iron regulatory protein by glyoxal. Since protein aggregation is at the core of many disorders, thus interest in this domain has increased significantly during the past years. METHODS: In our present study, the effect of glyoxal was monitored on human transferrin using multispectroscopic and multi-microscopic studies. RESULTS: Intrinsic fluorescence spectroscopy suggested changes in native conformation of human transferrin evident by decreased fluorescence and blue shift in the presence of glyoxal. Further, extrinsic fluorescence was retorted and the results showed the formation of aggregates; apparent by increased Congo red (CR) absorbance, Thioflavin T (ThT) and ANS fluorescence and TEM of human transferrin in the presence of glyoxal. Molecular docking was also employed to see which residues are at core of human transferrin and glyoxal interaction. Reactive oxygen species (ROS) generation assays revealed enhanced ROS levels by human transferrin after treatment with glyoxal. CONCLUSION: Thus, our study proposes that glyoxal induces the formation of aggregates in human transferrin. These aggregates further generate ROS which are key players in the complications associated with diabetes mellitus, giving our study clinical perspective.


Assuntos
Glioxal/química , Glioxal/farmacologia , Agregados Proteicos/efeitos dos fármacos , Transferrina/química , Células Cultivadas , Humanos , Linfócitos/efeitos dos fármacos , Linfócitos/metabolismo , Microscopia Eletrônica de Transmissão , Simulação de Acoplamento Molecular , Ligação Proteica , Espécies Reativas de Oxigênio , Espectrometria de Fluorescência
7.
J Agric Food Chem ; 67(28): 7961-7967, 2019 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-31260294

RESUMO

Food-derived glycated phospholipids is potentially hazardous to human health. However, there are few studies on the effects of lipids on the formation of glycated phospholipids. In this work, two model systems were established: (1) a model system including 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (PE), glucose, and Fenton reagent and (2) a model system including PE, glucose, and five kind of vegetable oils. The contents of carboxymethyl-PE, carboxyethyl-PE, Amadori-PE, hydroxyl radical (OH•), glyoxal, and methylglyoxal were determined with high-performance liquid chromatography mass spectrometry. The results of the first model system showed that OH• oxidized glucose to produce glyoxal and methylglyoxal, which then reacted with PE to form carboxymethyl-PE and carboxyethyl-PE. OH• also oxidized Amadori-PE to form carboxymethyl-PE. The results of the second model system showed that vegetable oils with higher number of moles of carbon-carbon unsaturated double bond in vegetable oil per kilogram could produce more OH•, which promote the formation of carboxymethyl-PE and carboxyethyl-PE by oxidizing glucose and oil. We elucidated the effects of oils on the formation of glycated phospholipids in terms of OH• and intermediates. This work will contribute to better understanding the formation mechanism of glycated phospholipids with oil.


Assuntos
Radical Hidroxila/química , Lipídeos/química , Fosfolipídeos/química , Cromatografia Líquida de Alta Pressão , Glucose/química , Glicosilação , Glioxal/química , Reação de Maillard , Espectrometria de Massas , Modelos Químicos , Oxirredução , Aldeído Pirúvico/química
8.
Int J Biol Macromol ; 136: 469-475, 2019 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-31216449

RESUMO

Chitosan-glyoxal/Polyvinylpyrrolidone/MoS2 (CSG/PVP/MoS2) nanocomposites were synthesized via hydrothermal-ultrasonic method. The CSG/PVP/MoS2 nano catalyst was characterized by XRD, UV-visible spectroscopy, FTIR, SEM and X-ray photoelectron spectroscopy, and diclofenac was used for the adsorption and photo-degradation test. SEM revealed the CSG/PVP/MoS2 nanocomposite has coarse and semi-flake structure and UV-vis absorbance spectra indicated its strong UV light response. Additionally, the CSG/PVP/MoS2 presents enhanced adsorption-photocatalytic activities in comparison to CSG/PVP, and the degradation was reaching 94.5%. Kinetic study results demonstrated that the diclofenac photo-degradation could be explained by pseudo-first-order model. The material may have great potential in wastewater treatment applications. The synthesized nanomaterials were tested for their antibacterial properties against microorganisms Staphylococcus epidermidis and Pseudomonas aeruginosa. The antimicrobial property CSG/PVP/MoS2 nanocomposite was observed with a maximum of zone inhibition.


Assuntos
Quitosana/química , Dissulfetos/química , Glioxal/química , Molibdênio/química , Preparações Farmacêuticas/química , Preparações Farmacêuticas/isolamento & purificação , Fotólise , Povidona/química , Adsorção , Antibacterianos/química , Antibacterianos/farmacologia , Catálise , Cinética , Nanocompostos/química , Pseudomonas aeruginosa/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Poluentes Químicos da Água/química , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água
9.
Int J Biol Macromol ; 135: 569-581, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-31150675

RESUMO

In this work, chitosan (Chi) was cross-linked with glyoxal (Gly) and deposited onto glass plate to be a superior adsorbent film for two structurally different reactive orange 16 (RO-16) and methyl orange (MO) dyes by using non-conventional adsorption system without filtration process. The characterizations indicate that the cross-linked chitosan-glyoxal (Chi-Gly) film has a low swelling index, high adherence strength on glass plate, amine group (NH2) content was 32.52%, and pHpzc of ∼6.0 indicating a negative surface charge occurs above pHpzc. The adsorption isotherm data of RO-16 and MO by Chi-Gly film were in agreement with Langmuir isotherm, with maximum adsorption capacities of 1554.3 mg/g and 1451.9 mg/g, respectively. The pseudo-first-order kinetic model best described the kinetic data. The adsorption process was spontaneous and exothermic in nature at Chi-Gly film thickness of 8.55 µm, and pH ~3. The mechanism of adsorption included mainly electrostatic attractions, dipole-dipole hydrogen bonding interactions, n-π stacking attractions, and Yoshida H-bonding. This study reveals that immobilized Chi-Gly film as a good candidate for adsorption of reactive and acid dyes as it does not require any filtration process and adsorbent recovery during and post-adsorption process.


Assuntos
Compostos Azo/química , Quitosana/química , Corantes/química , Glioxal/química , Poluentes Químicos da Água/química , Adsorção , Compostos Azo/isolamento & purificação , Corantes/isolamento & purificação , Concentração de Íons de Hidrogênio , Cinética , Termodinâmica , Poluentes Químicos da Água/isolamento & purificação
10.
J Agric Food Chem ; 67(22): 6350-6358, 2019 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-31083944

RESUMO

α-Dicarbonyls are reactive intermediates formed during Maillard reactions and carbohydrate degradation. The formation of seven α-dicarbonyls was characterized in solutions containing dairy related carbohydrates (galactose, glucose, lactose, and galacto-oligosaccharides (GOS)) during incubations at 40 and 50 °C with and without Nα-acetyl-l-lysine at pH 6.8 for up to 2 months. The concentrations of α-dicarbonyls in samples of monosaccharides with Nα-acetyl-l-lysine were found to be 3-deoxyglucosone (3-DG) > 3-deoxygalactosone (3-DGal) > glyoxal > glucosone, galactosone > methylglyoxal > diacetyl. The presence of Nα-acetyl-l-lysine resulted in up to 100-fold higher concentrations of C6 α-dicarbonyls but lesser formation of glyoxal in the monosaccharide-containing models compared to what was observed in the absence of Nα-acetyl-l-lysine. Galactose incubated with Nα-acetyl-l-lysine generated the highest concentrations of 3-DGal (up to 130 µM), glyoxal (up to 100 µM), and methylglyoxal (up to 9 µM) compared to the other carbohydrates during incubation. Surprisingly, 3-DG (1500 µM) and 3-DGal (80 µM) were formed at levels of 2 orders of magnitude higher in solutions of GOS in the absence of Nα-acetyl-l-lysine as compared to the other carbohydrates at 40 °C, while GOS generated the lowest levels of glyoxal. GOS are widely used as an ingredient in various types of foods products, and it is therefore of importance to consider the risk of generating high levels of the reactive C6 α-dicarbonyl, 3-DG, in these types of products. This study contributes to the understanding of major α-dicarbonyl formation as affected by the presence of primary amines in GOS-, lactose-, and galactose-containing solutions under moderate heating in liquid foods.


Assuntos
Galactose/química , Glucose/química , Glioxal/química , Lactose/química , Lisina/química , Leite/química , Oligossacarídeos/química , Animais , Bovinos , Laticínios/análise , Temperatura Alta , Reação de Maillard , Oxirredução , Aldeído Pirúvico/química
11.
Int J Biol Macromol ; 134: 1145-1155, 2019 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-31132439

RESUMO

This investigation studied the removal of Cu2+, Pb2+, Cd2+, Zn2+, Ni2+ and Cr6+ ions from synthesised wastewater using modified chitosan macromolecules. On this note, chitosan beads (CS) were prepared and cross-linked with glyoxal solution. It was found that cross-linking increased the beads mechanical strength and chemical stability in acid solution and also increased the crystallinity of the beads in the process, which is a shortcoming, as the beads tend to have reduced adsorption capacity. To reduce this shortcoming, the cross-linked chitosan beads (DCS) were grafted with diethylenetriamine. The beads were characterised prior to adsorption studies. The amine concentration of the grafted cross-linked beads (GDCS) was observed to be nearly the same as the adsorption capacity (qmax); this concludes that the amine group of chitosan are the main reactive group. Also, the qmax was found to be 6.3 mmol/g with a 44.2% degree of grafting. The kinetics of the adsorption process was described reasonably well with the Swan model, where the experimental and simulated data were in close agreement. The effective diffusion coefficients (Deff) obtained by fitting the model to experimental data were found to be between 2.25·10-10 to 2.50·10-10 for Cu2+, Pb2+, Cd2+, Zn2+, Ni2+ and Cr6+ adsorption unto GDCS.


Assuntos
Quitosana/química , Reagentes para Ligações Cruzadas/química , Glioxal/química , Íons/química , Metais/química , Poliaminas/química , Adsorção , Algoritmos , Estabilidade de Medicamentos , Concentração de Íons de Hidrogênio , Cinética , Modelos Teóricos , Análise Espectral , Poluentes Químicos da Água/química
12.
Food Chem ; 289: 320-327, 2019 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-30955619

RESUMO

The role of Reactive Carbonyl Species (RCS) derived from the Maillard reaction and ascorbic acid degradation on brown color formation was investigated in orange juice during storage. Eight RCS were monitored in aseptic juice over an 8-week period under refrigerated (4 °C) and accelerated conditions (35 °C). Significant changes in RCS concentrations were reported and positively correlated with color formation. Recombination experiments demonstrated the significant role of 3-deoxyglucosone and acetol on color formation as well as their interactions with glyoxal and methylglyoxal that lead to an increase in browning. Isotopic enrichment techniques further identified fructose as the main precursor of RCS, indicating the important role of Maillard reaction as a mechanism of non-enzymatic browning during orange juice storage. Finally, among the amino acids, tryptophan and glutamine showed the largest percentage losses in orange juice during storage and were reported to significantly impact the RCS composition and color formation.


Assuntos
Citrus sinensis/química , Sucos de Frutas e Vegetais/análise , Aminoácidos/análise , Cromatografia Líquida de Alta Pressão , Citrus sinensis/metabolismo , Cor , Desoxiglucose/análogos & derivados , Desoxiglucose/análise , Armazenamento de Alimentos , Frutose/química , Glioxal/análise , Glioxal/química , Reação de Maillard , Espectrometria de Massas , Espectrofotometria Ultravioleta , Temperatura Ambiente
13.
Molecules ; 24(8)2019 Apr 18.
Artigo em Inglês | MEDLINE | ID: mdl-31003408

RESUMO

The inhibitory effects of baijiu vinasse extract and its phenolic acid compounds on the Nε-carboxymethyllysine (CML) formation from dairy food were investigated. The inhibitory effect of the baijiu vinasse extract against CML formation was 43.2% in the casein and D-glucose model, which used 6 mL of the 70% acetone extract at 60 °C for 40 min. The HPLC-MS/MS profiles of the vinasse extract indicated that vanillic, chlorogenic, p-coumaric, sinapic, caffeic, ferulic, and syringic acids were seven major phenolic acid compounds. Furthermore, the inhibitory mechanism of the phenolic acid compounds in the model of dairy food was discussed by the trapping and scavenging of glyoxal. The results of this study exhibit that seven major antioxidant phenolic acid compounds may play important roles in the antioxidant activity and CML inhibition of the vinasse extract in a model of dairy foods.


Assuntos
Laticínios/análise , Depuradores de Radicais Livres/análise , Glioxal/química , Lisina/análogos & derivados , Resíduos/análise , Vinho , Antioxidantes/análise , Compostos de Bifenilo/química , Lisina/química , Fenóis/análise , Picratos/química
14.
Food Funct ; 10(5): 2491-2503, 2019 May 22.
Artigo em Inglês | MEDLINE | ID: mdl-30977506

RESUMO

It is important to inhibit food-derived potentially hazardous glycated lipids with natural products. A model reaction inhibition system was established, and products were identified with high-performance liquid chromatography-mass spectrometry (HPLC-MS/MS) to study the inhibitory effects of four types of catechins on the formation of glycated 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (DPPE) products. The results show that the percentage inhibition of epicatechin (EC), epicatechin gallate (ECG), epigallocatechin (EGC) and epigallocatechin gallate (EGCG) on the formation of carboxymethyl 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (CM-DPPE) are 38.84%, 33.31%, 20.71% and 22.66%, respectively. The percentage inhibition of EC, ECG, EGC and EGCG on the formation of carboxyethyl 1,2-dipalmitoyl-sn-glycero-3-phosphoethanolamine (CE-DPPE) is 42.04%, 41.99%, 31.70% and 36.24%, respectively. In addition, catechin can capture glyoxal (GO) and methylglyoxal (MGO) to produce multiple products. O-Benzoquinone, the oxidation products of catechin, also captures DPPE to produce quinone-DPPE adducts. Therefore, there are two inhibitory mechanisms of tea-derived catechin for glycated DPPE: (1) catechin inhibits the formation of CM-DPPE and CE-DPPE by trapping reactive GO and MGO; and (2) catechin is oxidized to o-benzoquinone. O-Benzoquinone reacts with DPPE through nucleophilic substitution, which competes with the reaction between glucose and DPPE. This study will provide a theoretical basis for the use of natural products to inhibit the formation of food-derived glycated lipids.


Assuntos
Catequina/química , Fosfatidiletanolaminas/química , Quinonas/química , Glioxal/química , Oxirredução , Aldeído Pirúvico/química
15.
Biomed Mater ; 14(3): 034103, 2019 04 02.
Artigo em Inglês | MEDLINE | ID: mdl-30836335

RESUMO

Hydroxyl terminated oligo(ε-caprolactone) (OCL) monolayers were reversibly cross-linked forming two dimensional networks (2D) at the air-water interface. The equilibrium reaction with glyoxal as the cross-linker is pH-sensitive. Pronounced contraction in the area of the prepared 2D OCL films in dependence of surface pressure and time revealed the process of the reaction. Cross-linking inhibited crystallization and retarded enzymatic degradation of the OCL film. Altering the subphase pH led to a cleavage of the covalent acetal cross-links. The reversibility of the covalent acetal cross-links was proved by observing an identical isotherm as non-cross-linked sample. Besides as model systems, these customizable reversible OCL 2D networks are intended for use as pH responsive drug delivery systems or functionalized cell culture substrates.


Assuntos
Materiais Biocompatíveis/química , Caproatos/química , Glioxal/química , Lactonas/química , Água/química , Reagentes para Ligações Cruzadas/química , Cristalização , Sistemas de Liberação de Medicamentos , Concentração de Íons de Hidrogênio , Lipase/química , Microscopia/métodos , Estrutura Molecular , Poliésteres/química , Polímeros/química , Espectrofotometria Infravermelho , Propriedades de Superfície , Engenharia Tecidual/métodos
16.
Int J Biol Macromol ; 129: 98-109, 2019 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-30735780

RESUMO

A crosslinked chitosan-glyoxal/TiO2 nanocomposite (CCG/TNC) was synthesized by loading different ratios of TiO2 nanoparticles into polymeric matrix of crosslinked chitosan-glyoxal (CCG) to be a promising biosorbent for methyl orange (MO). Box-Behnken design (BBD) in response surface methodology (RSM) was applied to optimize various process parameters, viz., loading of TiO2 nanoparticles into CCG polymeric matrix (A: 0%-50%), adsorbent dose (B: 0.04-0.14 g/50 mL), solution pH (C: 4-10), and temperature (D: 30-50 °C). The highest MO removal efficiency of 75.9% was observed by simultaneous interactions between AB, AC, and BC. The optimum TiO2 loading, adsorbent dosage, solution pH, and temperature were (50% TiO2: 50% chitosan labeled as CCG/TNC-50), 0.09 g/50 mL, 4.0, and 40 °C. The adsorption of MO from aqueous solution by using CCG/TNC-50 in batch mode was evaluated. The kinetic results were well described by the pseudo-first order kinetic, and the equilibrium data were in agreement with Langmuir isotherm model with maximum adsorption capacity of 416.1 mg/g. The adsorption mechanism included electrostatic attractions, n-π stacking interactions, dipole-dipole hydrogen bonding interactions, and Yoshida H-bonding.


Assuntos
Compostos Azo , Quitosana , Glioxal , Nanocompostos , Titânio , Adsorção , Algoritmos , Compostos Azo/química , Fenômenos Químicos , Quitosana/química , Glioxal/química , Concentração de Íons de Hidrogênio , Cinética , Modelos Teóricos , Nanocompostos/química , Nanocompostos/ultraestrutura , Análise Espectral , Eletricidade Estática , Titânio/química , Poluentes Químicos da Água
17.
Anal Biochem ; 573: 51-66, 2019 05 15.
Artigo em Inglês | MEDLINE | ID: mdl-30796906

RESUMO

Glyoxal (GO) and methylglyoxal (MGO) are two important biomarkers in diabetes. Analytical methods for determination of GO and MGO in serum samples are either HPLC with UV-Vis (low sensitivity) or MS/MS (expensive) detection. These disadvantages have hampered the introduction of these biomarkers as a routine analyte for diabetes diagnostics into the clinical laboratory. In this study, we introduce a UHPLC method with fluorescence detection for the measurement of GO and MGO in serum samples by pre-column derivatization at neutral pH with 5, 6-diamino-2,4-dihydroxypyrimidine sulfate (DDP) to form lumazines. The method was validated as per FDA guidelines. Using this method, we have determined GO and MGO in a variety of animal serum samples, and for example, determined the GO and MGO concentration in adult bovine serum to be 852 ±â€¯27 and 192 ±â€¯10 nmol/L, respectively. In human serum, GO and MGO levels in non-diabetic subjects (n = 14) were determined to be 154 ±â€¯88 and 98 ±â€¯27 nmol/L, and in serum samples from subjects with diabetes (n = 14) 244 ±â€¯137 and 190 ±â€¯68 nmol/L, respectively. In addition, interference studies showed that physiological serum components did not lead to an artificial increase in the levels of GO and MGO.


Assuntos
Cromatografia Líquida de Alta Pressão/métodos , Corantes Fluorescentes/química , Glioxal/sangue , Aldeído Pirúvico/sangue , Idoso , Idoso de 80 Anos ou mais , Animais , Calibragem , Cromatografia Líquida de Alta Pressão/normas , Diabetes Mellitus/patologia , Feminino , Glioxal/química , Glioxal/normas , Humanos , Concentração de Íons de Hidrogênio , Limite de Detecção , Masculino , Espectrometria de Massas , Pessoa de Meia-Idade , Pteridinas/química , Aldeído Pirúvico/química , Aldeído Pirúvico/normas , Reprodutibilidade dos Testes
18.
Food Chem ; 271: 87-93, 2019 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-30236745

RESUMO

The ability of α-dicarbonyls, glyoxal (GO) and methyl-glyoxal (MGO) (2 M), to induce the formation of allysine in ß-lactoglubulin (LAC), and myofibrillar proteins (MP) (2 mg/mL) during incubation at 80 °C for 48 h, was studied. Both GO and MGO induced the formation of allysine in all tested proteins with GO being more reactive (23.8 and 8.6 nmoles/mg protein in LAC and MP respectively after 6 h) than MGO (2.6 and 3.1 nmoles/mg protein at the same sampling point). LAC seemed to be more susceptible to the glycation reactions than MP. The concentration of allysine decreased at 24 h along with a concomitant increase of advanced-glycation end-products suggesting that allysine may be involved in the formation of fluorescent adducts. The water-holding capacity and trypsin-chymotrypsin digestibility of the proteins decreased during the incubation assay. The mechanisms by which α-dicarbonyls-mediated carbonylation likely influenced the impairment of such protein properties are thoroughly discussed.


Assuntos
Ácido 2-Aminoadípico/análogos & derivados , Glioxal/química , Lactoglobulinas/química , Ácido 2-Aminoadípico/química , Produtos Finais de Glicação Avançada , Aldeído Pirúvico , Água
19.
Int J Biol Macromol ; 122: 713-722, 2019 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-30399384

RESUMO

The recent study focused on lignin-phenol-glyoxal (LPG) as an alternative way to replace toxic formaldehyde used in commercially available wood adhesives. The concern of the uses of carcinogenic formaldehyde in wood adhesive industry has become major problem over human health, environmental and economy issues. In this study, lignin isolated from Kenaf (Hibiscus cannabinus) via soda and Kraft pulping were modified into SLPG (soda lignin-phenol-glyoxal) and KLPG (Kraft lignin-phenol-glyoxal) adhesives and were compared to phenol-formaldehyde (PF). Complementary analyses such as Fourier Transform Infrared (FTIR) spectroscopy, 1H and 13C Nuclear Magnetic Resonance (NMR) spectroscopy, thermal stability; Thermogravimetric analysis (TGA) and Differential Scanning Calorimetry (DSC) were utilized to characterize all isolated lignin samples. The physical properties of the resins were further characterized in term of viscosity, gel time and total solid content. It was found that soda lignin comprised higher phenolic OH content and greater molecular weight compared to Kraft lignin. Various molar ratio of adhesives were applied on plywood and were mechanically tested. The 30% (w/w) SLPG has shown to have higher tensile strength and internal bonding stress at 72.08 MPa and 53.83 N mm-2 respectively to that of PF.


Assuntos
Adesivos/química , Glioxal/química , Hibiscus/química , Lignina/química , Madeira , Fenômenos Mecânicos
20.
Food Chem ; 272: 679-687, 2019 Jan 30.
Artigo em Inglês | MEDLINE | ID: mdl-30309598

RESUMO

Nonenzymatic glycosylation (NEG) can generate advanced glycation end products (AGEs) and its intermediates α-dicarbonyl compounds, which contribute to the risk of diabetes. This study investigated the anti-glycation mechanisms and structure-activity relationship of (+)-catechin (CC) and (-)-epicatechin (EC). The results showed that the effect of CC on inhibiting AGEs was significantly better than that of EC (p < 0.05). By exploring the mechanism, we found that there was no significant difference in the ability of CC and EC to capture α-dicarbonyl compounds. But CC was found to be more efficient than EC to inhibit RO, OH and CHO radicals generation, which may be the primary reason that CC was more effective than EC on AGEs inhibition. What's more, CC showed better inhibitory effect on ß-glucosidase that was close to the molecular docking study. Our results will provide a theoretical foundation for development of different structure of procyanidins as natural AGEs inhibitors in food and medicine.


Assuntos
Biflavonoides/química , Catequina/química , Produtos Finais de Glicação Avançada/química , Proantocianidinas/química , Biflavonoides/metabolismo , Sítios de Ligação , Catequina/metabolismo , Cromatografia Líquida de Alta Pressão , Produtos Finais de Glicação Avançada/metabolismo , Glioxal/química , Humanos , Simulação de Acoplamento Molecular , Proantocianidinas/metabolismo , Estrutura Terciária de Proteína , Relação Estrutura-Atividade , Espectrometria de Massas em Tandem , alfa-Amilases/antagonistas & inibidores , alfa-Amilases/metabolismo , beta-Glucosidase/antagonistas & inibidores , beta-Glucosidase/metabolismo
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