The role of flavonoids in mitigating food originated heterocyclic aromatic amines that concerns human wellness

Meat products are an important part in our daily diet,providing valuable nutrients for the human body.However,heating processes cause the meat to become more appetizing with changes in texture,appearance,flavor,and chemical properties by the altering of protein structure and other ingredients.As one kind of cooking-induced contaminants,heterocyclic aromatic amines(HAAs)are widely present in protein aceous food products with strong carcinogenic and mutagenic properties.In order to promote the safety of traditional meat products,this review focused on the formation,metabolism,biological monitoring and inhibitory mechanism of HAA.An overview of the formation pathways,hazards,and control methods of HAAs during food processing in recent years was studied,aiming to provide some valuable information for exploring effective methods to inhibit the production of associated hazards during food processing.Systematic selection of different types of flavonoids to explore their effects on the formation of HAAs in an actual barbecue system can provide theoretical reference for effectively controlling the formation of HAAs and reducing their harm to human health.

Ionic liquid based dispersive liquid-liquid microextraction of aromatic amines in water samples

In this work, a new microextraction method termed ionic liquid based dispersive liquid-liquid microextraction （IL-DLLME） was demonstrated for the extraction of 2-methylaniline, 4-chloroaniline, 1-naphthylamine and 4-aminobiphenyl in aqueous matrices. After extraction the ionic liquid （IL） phase was injected directly into the high performance liquid chromatography （HPLC） system for determination. Some parameters that might affect the extraction efficiency were optimized. Under the optimum conditions, good linear relationship, sensitivity and reproducibility were obtained. The limits of detection （LOD, S/N = 3） for the four analytes were in the range of 0.45-2.6 μg L^-1. The relative standard deviations （R.S.D., n = 6） were in the range of 6.2-9.8%. This method was applied for the analysis of the real water samples. The recoveries ranged from 93.4 to 106.4%. The main advantages of the method are high speed, high recovery, good repeatability and volatile organic solvent-free.

Curing Reaction Kinetics of Epoxy Resin Using Dicyandiamide Modified by Aromatic Amines

The curing reaction and reaction mechanism of epoxy resin E-44, for which aromatic amine modified dicyandiamide was used as a curing reagent, were investigated by means of differential scanning calorimetry （DSC）. The results showed that the modified dicyandiamide had better curing characteristic than unmodified dicyandiamide for epoxy resin E-44, and the curing reaction could be carried out at moderate temperature. Apparent activation energy of the curing reaction was decreased appreciably from 123.829 kJ/mol to 61.550-64.405 kJ/mol, and reaction order was decreased from 0.941 to 0.896-0.900. Curing reaction mechanism also was discussed.

Predicting the Acute Toxicity of Aromatic Amines by Linear and Nonlinear Regression Methods

In current paper, a quantitative structure-activity relationship （QSAR） study was performed for the prediction of acute toxicity of aromatic amines. A set of 56 compounds was randomly divided into a training set of 46 compounds and a test set of 10 compounds. The electronic and topological descriptors computed by the Scigress package and Dragon software were used as predictor variables. Multiple linear regression （MLR） and support vector machine （SVM） were utilized to build the linear and nonlinear QSAR models, respectively. The obtained models with five descriptors show strong predictive ability. The linear model fits the training set with R2 = 0.71, with higher SVM values of R2 = 0.77. The validation results obtained from the test set indicate that the SVM model is comparable or superior to that obtained by MLR, both in terms of prediction ability and robustness.

A Novel Synthesis of N-Methyl-N-aryl Carbamates from Aromatic Amines and Dimethyl Carbonate Catalyzed by K_2CO_3/Bu_4NBr

A facile synthesis of N-methyl-N-aryl carbamates from aromatic amines and dimethyl carbonate (DMC) has been achieved with high yields in the presence of potassium carbonate (K2CO3)and tetrabutylammonium bromide (Bu4NBr) under solvent-free conditions.

Ce(SO_4)_2-mediated Oxidative Coupling of Primary Aromatic Amines in Water

The oxidative coupling of primary aromatic amines was investigated. Ce（SO4）2 can mediate the oxidative coupling of primary aromatic amines in water to dimers, trimers and/or tetramers, which depended on the substituents of primary aromatic amines. When 2,6-dimethylaniline or 2,6-diethylaniline was used as substrate, dimer, and tetramer were formed as major products. When 2,6-diisopropylaniline or 2,6-dihaloanilines was used as substrate, dimer, and trimer were formed. The mechanistic aspect was also investigated.

Inhibition of Heterocyclic Aromatic Amines in Pork Chops Using Complex Marinades with Natural Antioxidants

Five marinades were developed using natural antioxidants. Based on a consumer test of the appearance, three marinades were chosen for further investigation: an oregano, an acerola and a Dijon marinade, the Dijon marinade containing acerola, sumac and oregano. A barbecue and a sumac marinade were not included in the further study. In a home use test, consumers barbecued pork chops with the three marinades. Most of the consumers preferred the oregano and the Dijon marinade, while the acerola marinade was less liked. After controlled cooking using both direct and indirect heat to a core temperature of 65°C and 80°C, the content of the heterocyclic aromatic amines (HCA) PhiP, MeIQx, DiMeIQx, Harman and Norharman was analysed. All of the marinades reduced the content of MeIQx and DiMeIQx, although only with indirect heat, while PhiP was reduced using both grilling methods. Surprisingly, in particular the content of Harman—and to a lesser extent Norhaman—was very high in the Dijon-marinated chops. The results demonstrated that it was possible to develop well-liked marinades that can reduce the formation of selected HCAs.

ALLYLATION OF AROMATIC AMINES VIA ALLYLDIALKYLTELLURONIUM SALTS

Allyldialkyltelluronium bromides were treated with aromatic amines in 1,2-dichloroethane,readily giving allyl aryl amines in excel- lent yields.This method provides a convenient one-pot reaction for the synthesis of allylic amines.

Critical steps in the production of oil from oilseed to reduce heterocyclic aromatic amines

Contamination by the heterocyclic aromatic amines(HAAs)norharman and harman is one of the risks in vegetable oil production,so oil producers strive to decrease their content in the end products.In this study,the effects of production conditions—specifically,two pretreatment methods(roasting and microwaving),four extraction methods(two pressing and two solvent extraction)and adsorption refining(four absorbents)—of five oils(flaxseed,peanut,rapeseed,sesame,and sunflower seed)were evaluated.The results showed that microwaving as a pretreatment produced significantly fewer HAAs than roasting(P<0.05).After two pretreatments,the HAA content of oils was ranked from high to low as follows:sunflower oil,sesame oil,flaxseed oil,rapeseed oil,and peanut oil.Solvent-extracted oils(9.16–316.73μg/kg)had fewer HAAs than pressed oils(26.61–633.93μg/kg).Using adsorbents reduced HAAs in oils from the initial 21.77–484.22 to 0.31–41.58μg/kg,and the removal rate reached 99.28%.This study provides critical HAA reduction strategies for application in the oil production process to obtain safe final products.

“On Water”Effect for Green Click Reaction:Spontaneous Polymerization of Activated Alkyne with“Inert”Aromatic Amine in Aqueous Media

Organic reactions in water have attracted great attention due to their advantages such as unique reaction performance and environmental friendliness.Organic reactions as well as polymerizations in aqueous media have been extensively investigated,and so far,there has been a massive amount of reporting about polymerizations in water.However,reports about click polymerization in water have been rare.Herein,click polymerization of activated alkyne and aromatic amine in aqueous media is developed.The“on water”effect facilitates polymerization in aqueous media better than in organic solvents,and its mechanism is deciphered through experimental data and theoretical calculations.Water participates in the reaction and reduces the energy barrier to some extent.Besides,polymerization makes it possible for aromatic amine with low reactivity to be linked.By using this strategy,polymers with high molecular weights can be obtained in high yields(up to 95.4%).They show good thermal stability and high refractivity.They can be photodegraded.The polymers with tetraphenylethylene moieties show aggregation-induced emission and can be used as materials for generating photopatterns and visualizing agents for specific staining of lysosome in living cells.

Copper-Promoted Conversion of Aromatic Amines into Trifluoromethylated Arenes： One-Pot Sandmeyer Trifluoromethylation

A simple copper-promoted one-pot Sandmeyer trifluoromethylation of aromatic amines with Langlois＇ reagent has been demonstrated. The reaction is performed in mild reaction conditions under an air atmosphere with good substrate scope and functional group compatibility. It provides an alternative and straightforward synthetic approach to access a variety of trifluoromethylated arenes.

Porous boronate affinity monolith for on-line extraction coupled to high-performance liquid chromatography for sensitive analysis of heterocyclic aromatic amines in food samples

A novel on-line solid-phase microextraction–high-performance liquid chromatography（SPME–HPLC）system was developed for the determination of heterocyclic aromatic amines（HAAs） in food samples. A poly（vinylphenylboronic acid-co-ethylene glycol dimethacrylate） polymer monolith was prepared for on-line efficient extraction and large-volume injection was used to increase the sensitivity of detection.The polymermonolith, based on a ternary porogen, was prepared by in situ polymerization of vinylphenylboronic acid（VPBA） and ethylene glycol dimethacrylate（EGDMA） in a fused-silica capillary column. It showed good permeability, high extraction capacity, and high selectivity. The column-tocolumn reproducibility was satisfactory, and the enrichment factors for HAAs were 3746–7414.Conditions influencing the on-line extraction efficiency, including p H of sample solutions, flow rate of extraction and desorption, and desorption volume, were investigated. The proposed method had low limit of detection（0.10–0.15 ng/L） and good linearity. Trace HAAs in roast beef and lamb samples were determined, and the amounts of 2-amino-3-methylimidazo[4,5-f]quinoline, 2-amino-3,4-dimethylimidazo[4,5-f]quinoline, 2-amino-3,8-dimethylimidazo[4,5-f]quinoxaline, 2-amino-3,4,8-trimethylimidazo[4,5-f]quinoxaline, and 2-amino-3,4,7,8-tetramethyl-3H-imidazo[4,5-f]quinoxaline in these samples were 0.235–2.08 ng/g. The recoveries for the five HAAs ranged from74.3% to 119%, and the relative standard deviation（RSDs） were less than 8.2%. The results showed that the proposed on-line method was highly sensitive for monitoring HAAs in different food samples.

Enantioselective and a-Regioselective Allylic Amination of Morita-Baylis-Hillman Acetates with Simple Aromatic Amines Catalyzed by Planarly Chiral Ligand/Palladium Catalyst

An asymmetric allylic amination of Morita-Baylis-Hillman acetates with simple aromatic amines catalyzed by planarly chiral ligand/palladium-catalyst was developed in good yield with excellent a-regioselectivity （a/γ up to 30 ： 1） and moderate enantioselectivity （up to 70% ee）.

Determination of primary aromatic amines using immobilized nanoparticles based surface-enhanced Raman spectroscopy

Primary aromatic amines （PAAs） are substances with toxicity and suspected human carcinogenicity. A facile method for highly sensitive detection of PAAs using surface-enhanced Raman spectroscopy （SERS） is reported. The immobilization of Au nanoparticles （AuNPs） on the glycidyl methacrylate-ethylene dimethacrylate （GMA-EDMA） materials makes the suhstrate a closely packed but not aggregated Au NP arrays which provides a prominent SERS enhancement. Four PAAs with different substituent groups, namely, p-toluidine, p-nitroaniline, benzidine and 4,4-methylene-bis-（2-chloroaniline） have been successfully identified and quantified. High sensitivity and good linear relationship between SERS signals and concentrations of PAAs are obtained for all four PAAs.

Crystallization-induced phosphorescence, remarkable mechanochromism, and grinding enhanced emission of benzophenone-aromatic amine conjugates

Pure organic luminogens with efficient room temperature phosphorescence（RTP） and remarkable mechanochromism are highly desired in view of their fundamental significance and technical applications. Herein, four twisted pure organic luminogens based on benzophenone and aromatic amines were synthesized and their photophysical properties were thoroughly investigated. They exhibit crystallization-induced phosphorescence（CIP）, giving bright fluorescence and phosphorescence dual emission in crystals. Upon grinding, they become amorphous and emit predominantly red-shifted fluorescence, demonstrating remarkable mechanochromism. Furthermore, three of them even demonstrate greatly enhanced emission upon grinding, which is rarely observed in twisted D-A structured luminogens.

Effect of woodchip types on heterocyclic aromatic amine formation and quality characteristics of smoked bacon

The impact of different woodchips(beech,oak,pear,and apple)on the contents of heterocyclic aromatic amines(HAAs)and quality characteristics of smoked bacon was investigated.The results indicated that the contents of total HAAs and non-polar HAAs in beech-and oak-smoked bacon were lower than that in pear-and apple-smoked bacon(P<0.05).There were no HAAs detectable in control(non-smoking)sample.The smoking process promoted the formation of free amino acids(FAA)in the smoked bacon.The total contents of FAA in beech-and oak-smoked bacon were higher than these in the pear-and apple-smoked bacons(P<0.05).The beech-smoked bacon had the highest L^(*)-value(P<0.05),and oak-smoked bacon had the lowest thiobarbituric acid-reactive substance(TBARS)value and carbonyl content(P<0.05).Additionally,woodchip types had no significant influence on a^(*)-value,b^(*)-value,moisture content,aw,T_(20),T_(21) and T_(22)(P>0.05).PCA of the HAA contents and quality characteristics could effectively differentiate that were unsmoked and smoked bacon.Therefore,woodchip types had a great influence on HAA contents and quality of smoked bacon.

The Oxirane Ring Opening of 2,3-endo-epoxybicyclo[3. 2 .0] hept-6-one by Amines at Alumina Surface

Stereospecific (trans) and regioselective nucleophilic opening of the title epoxide (I) by different amines at the alumina surface are described.

Immobilized silver nanoparticles on silica gel as an efficient catalyst in nitroarene reduction

Nanoparticles have properties that can be fine-tuned by their size as well as shape.Hence,there is significant current interest in preparing nano-materials of small size dispersity and to arrange them in close-packed aggregates.This letter describes a way of synthesising silver nanoparticles and their protection to aggregate by silica gel.The combination of catalytic quantities of immobilized silver nanoparticles with reductive ability of NaBH_4 efficiently reduces aromatic nitroarenes to the corresponding amines in aqueous medium.Noteworthy is that highly chemoselective reactions were achieved in the presence of other functional groups such as halogen and carboxylic acid groups.The silver particles immobilized on silica gel are stable in the presence of oxygen for several months.

PHOTOCHROMISM AND LUMINESCENCE OF DOPANT CHROMOPHORES THROUGH TWO-PHOTON IONIZATION IN POLYMER FILMS

Two-photon ionization and recombination processes of an aromatic chromophore doped in polymer films werestudied and the features of these processes were discussed in relation to photofunctional polymers, An aromatic moleculehaving low ionization potential, e.g., N,N,N',N'-tetramethyl-p-phenylene diamine doped in poly(methyl methacrylate)(PMMA) film was easily photoionized by intense laser ligh excitation, giving a colored radical cation (photochromism) anda trapped electron in PMMA matrix. As a reversed process, the radical cation recombined with the trapped electron, showingdiscoloration and emitting luminescence, either isothermal luminescence (ITL), or thermoluminescence (TL). In this report,ITL and TL through the charge recombination process were studied and the luminescence was suggested as a mean of the read-out of photorecording.

Samarium-promoted Chemoselective Reduction of Aromatic Nitro Compounds in Ionic Liquid

bState Key Laboratory of Organometallic Chemistry, Shanghai Institute of Organic Chemistry, Chinese Academy of Sciences, Shanghai 200032, China The differently substituted aromatic nitro compounds were chemoselectively reduced by Sm/HOAc system in an ionic liquid medium to afford aromatic amines. Under these conditions the other substituents, such as -X, -CHO, -COOH, -CN, -NHTos and -alkyl, remained intact. The notable advantages of this reaction are its mild conditions, simple operation, short reaction time, high yields and easy recycling of ionic liquid.