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1.
J Proteomics ; 297: 105128, 2024 Apr 15.
Artigo em Inglês | MEDLINE | ID: mdl-38382841

RESUMO

Investigating site-specific protein phosphorylation remains a challenging task. The present study introduces a two-step chemical derivatization method for accurate identification of phosphopeptides. Methylamine neutralizes carboxyl groups, thus reducing the adsorption of non-phosphorylated peptides during enrichment, while dimethylamine offers a cost-effective reagent for stable isotope labeling of phosphorylation sites. The derivatization improves the mass spectra obtained through liquid chromatography-tandem mass spectrometry. The product ions at m/z 58.07 and 64.10 Da, resulting from dimethylamine-d0 and dimethylamine-d6 labeled phosphorylation sites respectively, can serve as report ions. Derivatized phosphopeptides from casein demonstrate enhanced ionization and formation of product ions, yielding a significant increase in the number of identifiable peptides. When using the parallel reaction monitoring technique, it is possible to distinguish isomeric phosphopeptides with the same amino acid sequence but different phosphorylation sites. By employing a proteomic software and screening the report ions, we identified 29 endogenous phosphopeptides in 10 µL of human saliva with high reliability. These findings indicate that the two-step derivatization strategy has great potential in site-specific phosphorylation and large-scale phosphoproteomics research. SIGNIFICANCE: There is a significant need to improve the accuracy of identifying phosphoproteins and phosphopeptides and analyzing them quantitatively. Several chemical derivatization techniques have been developed to label phosphorylation sites, thus enabling the identification and relative quantification of phosphopeptides. Nevertheless, these methods have limitations, such as incomplete conversion or the need for costly isotopic reagents. Building upon previous contributions, our study moves the field forward due to high efficiency in site-specific labeling, cost-effectiveness, improved sensitivity, and comprehensive product ion coverage. Using the two-step derivatization approach, we successfully identified 29 endogenous phosphopeptides in 10 µL of human saliva with high reliability. The outcomes underscore the possibility of the method for site-specific phosphorylation and large-scale phosphoproteomics investigations.


Assuntos
Fosfopeptídeos , Proteômica , Humanos , Fosfopeptídeos/análise , Marcação por Isótopo/métodos , Proteômica/métodos , Reprodutibilidade dos Testes , Indicadores e Reagentes , Fosforilação , Íons , Dimetilaminas
2.
J Hazard Mater ; 465: 133439, 2024 Mar 05.
Artigo em Inglês | MEDLINE | ID: mdl-38218035

RESUMO

Uridine-disphosphate glucuronosyltransferase 1A9 (UGT1A9), an important detoxification and inactivation enzyme for toxicants, regulates the exposure level of environmental pollutants in the human body and induces various toxicological consequences. However, an effective tool for high-throughput monitoring of UGT1A9 function under exposure to environmental pollutants is still lacking. In this study, 1,3-dichloro-7-hydroxy-9,9-dimethylacridin-2(9H)-one (DDAO) was found to exhibit excellent specificity and high affinity towards human UGT1A9. Remarkable changes in absorption and fluorescence signals after reacting with UGT1A9 were observed, due to the intramolecular charge transfer (ICT) mechanism. Importantly, DDAO was successfully applied to monitor the biological functions of UGT1A9 in response to environmental pollutant exposure not only in microsome samples, but also in living cells by using a high-throughput screening method. Meanwhile, the identified pollutants that disturb UGT1A9 functions were found to significantly influence the exposure level and retention time of bisphenol S/bisphenol A in living cells. Furthermore, the molecular mechanism underlying the inhibition of UGT1A9 by these pollutant-derived disruptors was elucidated by molecular docking and molecular dynamics simulations. Collectively, a fluorescent probe to characterize the responses of UGT1A9 towards environmental pollutants was developed, which was beneficial for elucidating the health hazards of environmental pollutants from a new perspective.


Assuntos
Dimetilaminas , Poluentes Ambientais , Glucuronosiltransferase , Humanos , Corantes Fluorescentes , Uridina , Simulação de Acoplamento Molecular
3.
Chemosphere ; 351: 141244, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-38242515

RESUMO

Amines, which are classified as volatile organic compounds (VOCs), serve a variety of purposes in the fields of environmental monitoring, food safety, and healthcare diagnosis. The present technique for detecting amine levels involves sophisticated setups and bulky equipment. Here. In this study, a chemoresistive gas sensor is developed that is cost-effective and easy to operate at room temperature (RT). The sensor is designed specifically for the detection of Ammonia, dimethylamine (DMA), trimethylamine (TMA), and total volatile basic nitrogen (TVB-N). Using biphenyl-reduced graphene oxide (B-rGO) composite gas sensors effectively addresses the issues of low sensitivity-selectivity and long-term instability commonly observed in conventional amine sensors. B-rGO sensor produced sensitivity of ∼3500 and selectivity above 30 for TVB-N sensing. The sensor is stable for temperature fluctuations below 50 °C and shows stable sensing response for period of over 3 months. A Chemoresistive B-rGO sensor was developed using an ultrasonic spray deposition system with optimized flow rate of 50 mL/h. Rapid evaporation of solvent using hot plate has resulted in unique morphology for B-rGO film sensors. The highest sensitivity, ∼836, is obtained for 100 ppm of ammonia with ammonia > DMA > TMA as a sensitivity order. B-rGO showed almost seven times higher amine sensitivity than rGO which highlights the importance of biphenyl in the B-rGO composite. Sensor calibration curve has been presented in the study to understand change in the sensitivity of sensor with increasing analyte gas concentration. The calibration curve has an average R-squared value of 0.98.


Assuntos
Aminas , Amônia , Compostos de Bifenilo , Dimetilaminas , Grafite , Metilaminas , Temperatura , Nitrogênio
4.
Environ Sci Technol ; 58(3): 1563-1576, 2024 Jan 23.
Artigo em Inglês | MEDLINE | ID: mdl-38183415

RESUMO

Uncertain chemical mechanisms leading to brown carbon (BrC) formation affect the drivers of the radiative effects of aerosols in current climate predictions. Herein, the aqueous-phase reactions of methylglyoxal (MG) and typical reduced nitrogen species (RNSs) are systematically investigated by using combined quantum chemical calculations and laboratory experiments. Imines and diimines are identified from the mixtures of methylamine (MA) and ammonia (AM) with MG, but not from dimethylamine (DA) with the MG mixture under acidic conditions, because deprotonation of DA cationic intermediates is hindered by the amino groups occupied by two methyl groups. It leads to N-heterocycle (NHC) formation in the MG + MA (MGM) and MG + AM (MGA) reaction systems but to N-containing chain oligomer formation in the MG + DA (MGD) reaction system. Distinct product formation is attributed to electrostatic attraction and steric hindrance, which are regulated by the methyl groups of RNSs. The light absorption and adverse effects of NHCs are also strongly related to the methyl groups of RNSs. Our finding reveals that BrC formation is mainly contributed from MG reaction with RNSs with less methyl groups, which have more abundant and broad sources in the urban environments.


Assuntos
Poluentes Atmosféricos , Dimetilaminas , Aldeído Pirúvico , Carbono , Nitrogênio , Metilaminas , Aerossóis/análise
5.
Int J Biol Macromol ; 258(Pt 1): 128862, 2024 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-38134990

RESUMO

This study revealed the influence of phosphorylation-dimethylammonium chloride acyloxylation (PDACA) on the desizability, film properties, paste stability, and adhesion of biological starch macromolecules. A new starch-based sizing agent, phosphorylated-dimethylammonium chloride acyloxylated starch (PDACAS), was synthesized with degrees of substitution (DS) ranging from 0.033 to 0.065. Compared to control phosphorylated-quaternized starch (PQS, 87.4 %), the desizing efficiency of cotton yarns sized with PDACAS was ~94 %, exceeding the industrial minimum requirement of 90 %. The PDACAS film tensile properties were as follows: elongation at break of 3.31 %-3.78 %, bending endurance of 1131-1537 cycles, and tensile strength of 35.83-28.31 MPa, compared with those of acid-thinned starch (ATS) film (2.74 %, 957 cycles, and 38.12 MPa). The PDACAS had paste stability of ~92 %, compared with 83.3 % for ATS. The bonding forces (an indicator of adhesion to fibers) ranged from 107.1 N to 125.3 N for cotton roving, and 128.3 N to 148.7 N for polyester/cotton roving, which were significantly better than those of ATS (95 N for cotton and 117.9 N for polyester/cotton roving). Overall, PDACA treatment effectively avoided the adverse effect of high DS quaternization on the desizability of PQS and imparted good film properties, paste stability, and adhesion to starch.


Assuntos
Dimetilaminas , Fosfatos , Amido , Têxteis , Poliésteres , Resistência à Tração
6.
J Environ Manage ; 347: 119079, 2023 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-37748297

RESUMO

New particle formation (NPF) contributes more than half of the global aerosol. Diethanolamine (DEA) and methyldiethanolamine (MDEA) are the most common amines used to remove CO2 and H2S, which are lost to the atmosphere from CO2 chemical absorbers, livestock and consumer products and are involved in sulfuric acid (SA)-driven NPF. Ion-induced nucleation (IIN) is an important nucleation pathway for NPF. We investigated the role of IIN on DEA and MDEA enhancing SA-driven NPF using density functional method (DFT), molecular dynamics (MD) simulation and atmospheric cluster dynamics code (ACDC). The effects of SO42-, H3O+, NH4+, HSO4-, NO3-, ammonia, methylamine, dimethylamine, trimethylamine and water (W) on the nucleation of SA-DEA were further investigated. The enhancement ability of DEA is greater than that of dimethylamine (DMA) and MDEA. Participation in SA-based NPF is a removal pathway for DEA and MDEA. DEA-SA clusters are generated that not only aggregate DEA and SA molecules, but also increase further growth of atmospheric ions. The very low Gibbs formation free energy highlights the importance of ion-induced nucleation for SA-based NPF. The order of the ability of common atmospheric ions to increase the (SA)(DEA) cluster nucleation is SO42- > H3O+ > NH4+ > HSO4- > NO3-. The addition of 20 water molecules increases the (SA)(DEA)9 cluster from 1.882 nm to 2.053 nm, promoting SA-based NPF. The atmospheric ions accelerate the aggregation rate of the (SA)5(DEA)5 cluster within 15 ns?


Assuntos
Aminas , Dióxido de Carbono , Aminas/química , Ácidos Sulfúricos/química , Dimetilaminas/química , Água
7.
Food Funct ; 13(23): 12219-12233, 2022 Nov 28.
Artigo em Inglês | MEDLINE | ID: mdl-36341693

RESUMO

Treatment of anxiety and depression predominantly centres around pharmacological interventions, which have faced criticism for their associated side effects, lack of efficacy and low tolerability. Saffron, which is reportedly well tolerated in humans, has been recognised for its antidepressant and anti-anxiety properties. Indeed, we previously reported upon the efficacy of saffron extract supplementation in healthy adults with subclinical anxiety. However, the molecular aetiology remains unclear. In a rodent model of low-grade chronic inflammation, we explored the impact of a saffron extract (Safr'Inside™) supplemented at a physiological dose, which equated to 22 ± 1.2 mg per day human equivalent dose for a person of 60 kg. Behavioural tests (Open Field task, Y maze, Novel object recognition), caecal 16S rRNA microbial sequencing, caecal 1H NMR metabolomic analysis and 2DE brain proteomic analyses were completed to probe gut-brain axis interactions. Time occupying the centre of the Open Field maze (OF) was increased by 62% in saffron supplemented animals. This improvement in anxiety-related behaviour coincided with gut microbial shifts, notably Akkermansia, Muribaculaceae, Christensenellacae and Alloprevotella which significantly increased in response to saffron supplementation. Akkermansia and Muribaculaceae abundance negatively correlated with the neurotoxic metabolite dimethylamine which was reduced in saffron supplemented animals. Brain proteomic analysis highlighted several significantly altered proteins including ketimine reductase mu-crystallin which also correlated with dimethylamine concentration. Both dimethylamine and ketimine reductase mu-crystallin were associated with OF performance. This may be indicative of a novel interaction across the gut-brain axis which contributes to anxiety-related disorders.


Assuntos
Crocus , Microbioma Gastrointestinal , Microbiota , Animais , Camundongos , Adulto , Humanos , RNA Ribossômico 16S/genética , Microbioma Gastrointestinal/fisiologia , Proteômica , Microbiota/fisiologia , Modelos Animais de Doenças , Inflamação/tratamento farmacológico , Extratos Vegetais/farmacologia , Extratos Vegetais/uso terapêutico , Dimetilaminas
8.
Biochem Biophys Res Commun ; 630: 158-166, 2022 11 19.
Artigo em Inglês | MEDLINE | ID: mdl-36155062

RESUMO

We previously demonstrated that monosodium glutamate (MSG) consumption increases trimethylamine (TMA) level in the renal tissue as well as dimethylamine and methylamine levels in urine of rats, suggesting the effects of MSG on humans. To better define the findings, we investigated whether MSG consumption alters serum trimethylamine N-oxide (TMAO) level, and as a consequence, induces kidney injury in the rat model. Adult male Wistar rats (n = 40) were randomized to be fed with a standard diet (control group) or a standard diet with 0.5, 1.5 or 3.0 g% MSG corresponding to 7, 21, or 42 g/day in 60 kg man, respectively in drinking water (MSG-treated groups), or a standard diet with 3.0 g% MSG in drinking water which was withdrawn after 4 weeks (MSG-withdrawal group). Blood and urine samples were collected to analyze the TMAO levels using 1H NMR and markers of kidney injury. Fecal samples were also collected for gut microbiota analysis. We found serum TMAO levels increased and urinary TMAO excretion decreased during MSG consumption, in parallel with the increase of the neutrophil gelatinase-associated lipocalin (NGAL) excretion which subsided with the withdrawal of MSG. The fecal 16 S rRNA analysis during MSG consumption showed gut microbiota changes with a consistent suppression of Akkermansia muciniphila, a mucin producing bacteria, but not of TMA-producing bacteria. In conclusions, our findings suggested that prolonged high dose MSG consumption may cause TMAO accumulation in the blood via reduction of renal excretion associated with acute kidney injury. The mechanisms by which MSG reduced TMAO excretion require further investigation.


Assuntos
Água Potável , Glutamato de Sódio , Akkermansia , Animais , Dimetilaminas , Intestinos , Lipocalina-2 , Masculino , Metilaminas , Mucinas , Ratos , Ratos Wistar , Eliminação Renal , Verrucomicrobia
9.
Environ Sci Technol ; 56(19): 13644-13653, 2022 10 04.
Artigo em Inglês | MEDLINE | ID: mdl-36150089

RESUMO

Amines are frequently included in formulations of the herbicides glyphosate, 2,4-D, and dicamba to increase herbicide solubility and reduce herbicide volatilization by producing herbicide-amine salts. Amines, which typically have higher vapor pressures than the corresponding herbicides, could potentially volatilize from these salts and enter the atmosphere, where they may impact atmospheric chemistry, human health, and climate. Amine volatilization from herbicide-amine salts may additionally contribute to volatilization of dicamba and 2,4-D. In this study, we established that amines applied in herbicide-amine salt formulations undergo extensive volatilization. Both dimethylamine and isopropylamine volatilized when aqueous salt solutions were dried to a residue at ∼20 °C, while lower-vapor pressure amines like diglycolamine and n,n-bis-(3-aminopropyl)methylamine did not. However, all four amines volatilized from salt residues at 40-80 °C. Because amine loss typically exceeded herbicide loss, we proposed that neutral amines dominated volatilization and that higher temperatures altered their protonation state and vapor pressure. Due to an estimated 4.0 Gg N/yr applied as amines to major U.S. crops, amine emissions from herbicide-amine salts may be important on regional scales. Further characterization of worldwide herbicide-amine use would enable this contribution to be compared to the 285 Gg N/yr of methylamines emitted globally.


Assuntos
Dicamba , Herbicidas , Ácido 2,4-Diclorofenoxiacético , Aminas , Dicamba/química , Dimetilaminas , Herbicidas/química , Humanos , Metilaminas , Sais , Volatilização
10.
Proc Natl Acad Sci U S A ; 119(39): e2205668119, 2022 09 27.
Artigo em Inglês | MEDLINE | ID: mdl-36122231

RESUMO

Hydrolysis of N2O5 under tropospheric conditions plays a critical role in assessing the fate of O3, OH, and NOx in the atmosphere. However, its removal mechanism has not been fully understood, and little is known about the role of entropy. Herein, we propose a removal path of N2O5 on the water clusters/droplet with the existence of amine, which entails a low free-energy barrier of 4.46 and 3.76 kcal/mol on a water trimer and droplet, respectively, at room temperature. The free-energy barrier exhibits strong temperature dependence; a barrierless hydrolysis process of N2O5 at low temperature (≤150 K) is observed. By coupling constrained ab initio molecular dynamics (constrained AIMD) simulations with thermodynamic integration methods, we quantitively evaluated the entropic contributions to the free energy and compared NH3-, methylamine (MA)-, and dimethylamine (DMA)-promoted hydrolysis of N2O5 on water clusters and droplet. Our results demonstrate that methylation of NH3 stabilizes the product state and promotes hydrolysis of N2O5 by reducing the free-energy barriers. Furthermore, a quantitative analysis of the internal coordinate distribution of the reaction center and the relative position of surrounding species reveals that the significant entropic contribution primarily results from the ensemble effect of configurations observed in the AIMD simulations. Such an ensemble effect becomes more significant with more water molecules included. Lowering the temperature effectively minimizes the entropic contribution, making the hydrolysis more exothermic and barrierless. This study sheds light on the importance of the promoting effect of amines and the entropic effect on gas-phase hydrolysis reactions, which may have far-reaching implications in atmospheric chemistry.


Assuntos
Aminas , Água , Dimetilaminas , Hidrólise , Metilaminas , Água/química
11.
Med Sci Monit ; 28: e937784, 2022 Sep 07.
Artigo em Inglês | MEDLINE | ID: mdl-36068726

RESUMO

BACKGROUND Acute kidney injury (AKI) is one of the most common organ failures. An early diagnosis of AKI using specific biomarkers is essential for effective treatment. This study determined the serum concentrations of selected amino acids and amines using targeted liquid chromatography coupled with tandem mass spectrometry (LC-MS/MS) in patients with AKI during sepsis and septic shock treated in the Intensive Care Unit (ICU). MATERIAL AND METHODS A sample of 41 patients was divided into 2 groups: (1) patients with sepsis and septic shock along required continuous renal replacement therapy (CRRT) due to AKI (n=13), and (2) patients with sepsis and septic shock but without AKI (n=28). LC-MS/MS was used to measure a serum concentration of 6 amino acids and amines: arginine, ornithine, asymmetric dimethylarginine (ADMA), symmetric dimethylarginine (SDMA), dimethylamine (DMA), and citrulline. RESULTS There was a statistically significantly higher median DMA level in AKI patients compared to those without AKI (8.1 vs 5.2 umol/L; P=0.022). The results for the remaining molecules showed no significant differences (P>0.05). Patients with DMA ≥14.95 umol/L (n=5; 100%) and treated with CRRT presented DMA level below the cut-off point (n=7; 20%). Subjects with creatinine levels ≥1.19 mg/dL (n=11; 28%) and treated with CRRT presented creatinine levels below the cut-off point (n=1; 3%). CONCLUSIONS In patients with sepsis, increased serum levels of DMA were significantly associated with AKI requiring CRRT. It remains unclear whether increased DMA concentrations are secondary to sepsis-induced AKI or are a cause.


Assuntos
Injúria Renal Aguda , Terapia de Substituição Renal Contínua , Sepse , Choque Séptico , Injúria Renal Aguda/diagnóstico , Injúria Renal Aguda/etiologia , Injúria Renal Aguda/terapia , Aminas , Aminoácidos , Cromatografia Líquida , Creatinina , Dimetilaminas , Humanos , Unidades de Terapia Intensiva , Terapia de Substituição Renal , Estudos Retrospectivos , Sepse/complicações , Sepse/terapia , Choque Séptico/complicações , Espectrometria de Massas em Tandem
12.
Phys Chem Chem Phys ; 24(40): 24695-24705, 2022 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-36069146

RESUMO

We study the primary dissociation dynamics of aqueous formamide (HCONH2) and dimethylformamide (HCON(CH3)2) induced by photo-excitation at λ = 200 nm. The photolysis is recorded with sub-picosecond time resolution by UV pump-IR probe transient absorption spectroscopy. Formamide dissociates with a quantum yield of Φ(t = 20 ps) = 0.30 ± 0.05, t = 20 ps after the excitation. The rest of the excited formamide molecules return to the ground state within t = 1 ps and vibrationally relax towards equilibrium in t ≈ 10 ps. The only product observed is NH3. NH3 is produced with a yield of Φ(NH3) = 0.23 ± 0.10 on a timescale of τ = 3 ± 1 ps and likely constitutes the dominating product. The CO counter product to NH3 is not observed. Dimethylformamide is photolysed with a quantum yield of Φ(t = 30 ps) = 0.29 ± 0.05, t = 30 ps after the excitation. The photolysis of dimethylformamide produces CO on a time scale of τ ≈ 30 ps. The data indicate that dimethylamine and the N(CH3)2 radical are likely photoproducts.


Assuntos
Dimetilformamida , Água , Fotólise , Formamidas , Dimetilaminas
13.
Chemistry ; 28(58): e202202081, 2022 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-35916208

RESUMO

This study presents the transformation of olefins to branched amines by combining a hydroformylation/aldol condensation tandem reaction with the reductive amination in a combined multiphase system that can be recycled 9 times. The products are branched amines that are precursors for surfactants. Since the multiphase hydrofomylation/aldol condensation system has already been studied, the first step was to develop the partial hydrogenation of unsaturated aldehydes together with a subsequent reductive amination. The rhodium/phosphine catalyst is immobilized in a polar polyethylene phase which separates from the product phase after the reaction. Reaction and catalyst recycling are demonstrated by the conversion of the C14 -aldehyde 2-pentylnonenal with the dimethylamine surrogate dimethylammonium dimethylcarbamate to the corresponding tertiary amine with yields up to 88 % and an average rhodium leaching of less than 0.1 % per recycling run. Furthermore, the positive influence of a Bronsted acid and carbon monoxide on the selectivity are discussed. Finally, the two PEG based systems have been merged in one recycling approach, by using the product phase of the hydroformylation aldol condensation reaction for the reductive amination reaction. The yields are stable during a nine recycling runs and the leaching low with 0.09 % over the two recycling stages.


Assuntos
Alcenos , Ródio , Monóxido de Carbono , Estereoisomerismo , Aldeídos , Catálise , Aminas , Dimetilaminas , Tensoativos , Polietilenos
14.
Carbohydr Res ; 520: 108635, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35961080

RESUMO

Sugars were derivatized with N,O-dimethylhydroxylamine (DMHA) using a simple procedure. The disaccharides lactose and chitobiose and the human milk tetrasaccharides lacto-N-tetraose (LNT) and lacto-N-neotetraose (LNnT) were used as examples. The ß-glycosylamines were formed exclusively in good yields (80-84%). The derivatives were very well suited for RP-HPLC, giving rise to single peaks for each sugar, without the usual complications caused by mutarotation. The LNT- and LNnT-derivatives separated very well on an ordinary RP-HPLC column, despite their close structural similarity. Also, three human milk pentasaccharides (LNF I, II and III) were derivatized with DMHA. Again, good separation of these isomers was obtained. The DMHA derivatization was easily reversed. The free oligosaccharides were recovered quantitatively by mild acidic hydrolysis. To demonstrate usefulness on a preparative scale, an LNDI-rich human milk oligosaccharide fraction was derivatized, and three HPLC fractions (one major and two minor) were collected. Hydrolysis and desalting gave saccharides LNDI, LNnDII, and LNDII, the latter mixed with minor amounts of LNnDI.


Assuntos
Oligossacarídeos , Açúcares , Cromatografia Líquida de Alta Pressão/métodos , Dimetilaminas , Humanos , Lactose/análise , Leite Humano/química , Oligossacarídeos/química
15.
ChemSusChem ; 15(19): e202200868, 2022 Oct 10.
Artigo em Inglês | MEDLINE | ID: mdl-35900053

RESUMO

Upcoming biorefineries, such as lignin-first provide renewable aromatics containing unique aliphatic alcohols. In this context, a Cu-ZrO2 catalyzed hydrogen borrowing approach was established to yield tertiary amine from the lignin model monomer 3-(3,4-dimethoxyphenyl)-1-propanol and the actual lignin-derived monomers, (3-(4-hydroxyphenyl)-1-propanol and dihydroconiferyl alcohol), with dimethylamine. Various industrial metal catalysts were evaluated, resulting in nearly quantitative mass balances for most catalysts. Identified intermediates, side and reaction products were placed into a corresponding reaction network, supported by kinetic evolution experiments. Cu-ZrO2 was selected as most suitable catalyst combining high alcohol conversion with respectable aliphatic tertiary amine selectivity. Low pressure H2 was key for high catalyst activity and tertiary amine selectivity, mainly by hindering undesired reactant dimethylamine disproportionation and alcohol amidation. Besides dimethylamine model, diverse secondary amine reactants were tested with moderate to high tertiary amine yields. As most active catalytic site, highly dispersed Cu species in strong contact with ZrO2 is suggested. ToF-SIMS, N2 O chemisorption, TGA and XPS of spent Cu-ZrO2 revealed that imperfect amine product desorption and declining surface Cu lowered the catalytic activity upon catalyst reuse, while thermal reduction readily restored the initial activity and selectivity demonstrating catalyst reuse.


Assuntos
Cobre , Lignina , 1-Propanol , Aminas , Catálise , Dimetilaminas , Etanol , Hidrogênio
16.
ChemistryOpen ; 11(6): e202200060, 2022 06.
Artigo em Inglês | MEDLINE | ID: mdl-35678482

RESUMO

A new 'Off-On' system designed and synthesised by functionalisation of a naphthalene diimide (NDI) core with dimethylamine produces 4,9-bis(dimethylamino)-2,7-dioctylbenzo[lmn][3,8]-phenanthroline-1,3,6,8-(2H,7H)-tetraone, abbreviated as DDPT (1). DDPT 1 was synthesised using a simple strategy, namely aromatic nucleophilic substitution using Br2 -NDI with dimethylamine at 110 °C. DDPT was characterized by 1 H and 13 C NMR spectroscopy, ESI mass spectrometry and elemental analysis. DDPT 1 was then used for optical studies through protonation of its dimethylamine core with trifluoroacetic acid (TFA), blue-shifting the absorption band from 600 nm to 545 nm in solution. Interestingly, the fluorescence of DDPT 1 is weak in solution with a quantum yield Φ=0.09, which is significantly enhanced to Φ=0.78 upon addition of TFA. The limit of detection (LOD) was determined to 2.77 nm. Furthermore, DDPT 1 can be used for naked eyed detection not only under UV light (365 nm) but also using visible light, as clear changes can be clearly seen upon addition of TFA. The binding constant of DDPT was calculated to 2.1×10-3  m-1 . Importantly, DDPT 1 showed reversible switching by alternative addition of acid (TFA) and base (triethylamine) without loss of activity. Immobilised on paper, DDPT 1 can be used for strip-test sensing in which the colour changes from blue to reddish when expose to TFA vapours and reverse in the presence of triethylamine vapours.


Assuntos
Imidas , Naftalenos , Dimetilaminas , Imidas/química , Naftalenos/química , Espectrometria de Fluorescência , Ácido Trifluoracético
17.
J Pharm Biomed Anal ; 218: 114872, 2022 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-35696937

RESUMO

The possibility of N-Nitrosation in the absence of nitrosating agents was studied on model solutions and film coated tablets containing metformin. N-nitrosodimethylamine (NDMA) and N-nitrosation precursors (dimethylamine and nitrites) were determined using previously published fully validated analytical methods. Alternative routes to N-nitrosation were found. Dimethylamine can undergo an oxidation to nitrite in the presence of strong oxidants (e.g., H2O2), as was observed during wastewater treatment in several published works. The resulting nitrite can consecutively act as a nitrosating agent. We proved that the described reaction indeed leads to N-nitrosation (NDMA formation in case of dimethylamine precursor) in model solutions made of dimethylamine and H2O2. An experiment was designed in order to prove those reactions take place in dosage forms. Film coated tablets present a highly heterogenous system with several solid phases and low water activity, which is in stark contrast to the liquid wastewater, where this reaction was originally studied. Despite that, the described reaction took place even in the tablets, but only to a small degree. The amount formed via this alternative route corresponds to less than 10 % of the total formed NDMA. The pH optimum of this alternative route lies in the alkaline range which was confirmed by the determined NDMA concentration in model solutions. The solid phase system (i.e., tablets) was found to behave differently. The addition of Na2CO3 into the tablets during manufacture resulted in tablets without NDMA (cNDMA < LOQ) even in batches spiked with both dimethylamine and H2O2. Thus, adjusting the pH of the solid dosage forms remains a sufficient measure of controlling N-nitrosamines in the product, even in product with limit amounts of oxidating agent (H2O2) and N-nitrosation precursor (dimethylamine).


Assuntos
Peróxido de Hidrogênio , Nitritos , Dimetilaminas , Dimetilnitrosamina , Nitrosação , Preparações Farmacêuticas
18.
Sci Total Environ ; 837: 155464, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-35508234

RESUMO

Excited triplet species play an important role in the photolytic formation of 1O2 from carbonyls, but the related mechanism is still uncertain, due to lack of direct evidence. In this study, steady-state and transient photolysis of eleven carbonyls to produce 1O2 was investigated. Dicarbonyl displayed greater 1O2 production ability than monocarbonyl, while dicarbonyl containing both ketone and carboxyl groups connected by CC bond (i.e., pyruvic acid (PA)) showed the highest 1O2 steady-state concentration ([1O2]SS). For the first time, the production of 3PA* from PA with narrow energy gap was confirmed by laser flash photolysis technique and the second-order decay rate constant of 3PA* was 2.78 × 107 M-1 s-1. Quenching results verified the dominant contribution of 3PA* to 1O2 production from PA. Addition of inorganic salt or increase in solution pH showed negligible effect on 3PA*, but significantly decreased the [1O2]SS of PA by up to two orders of magnitude, due to reduction of hydrate content. Photolysis of methylglyoxal and dimethylamine mixture led to higher content of excited triplet species at pH ≈ 11 and remarkably enhanced [1O2]SS, which was 2.3 times of that from PA and dimethylamine mixture. These findings provide direct evidence for the contribution of transient species from carbonyls or their product to 1O2 formation in atmospheric environment.


Assuntos
Dimetilaminas , Oxigênio , Fotólise
19.
Environ Sci Technol ; 56(9): 5430-5439, 2022 05 03.
Artigo em Inglês | MEDLINE | ID: mdl-35435670

RESUMO

Alkaline gases such as NH3 and amines play important roles in neutralizing acidic particles in the atmosphere. Here, two common gaseous amines (dimethylamine (DMA) and trimethylamine (TMA)), NH3, and their corresponding ions in PM2.5 were measured semicontinuously using an ambient ion monitor-ion chromatography (AIM-IC) system in marine air during a round-trip cruise of approximately 4000 km along the coastline of eastern China. The concentrations of particulate DMA, detected as DMAH+, varied from <4 to 100 ng m-3 and generally decreased with increasing atmospheric NH3 concentrations. Combining observations with thermodynamic equilibrium calculations using the extended aerosol inorganics model (E-AIM) indicated that the competitive uptake of DMA against NH3 on acidic aerosols generally followed thermodynamic equilibria and appeared to be sensitive to DMA/NH3 molar ratios, resulting in molar ratios of DMAH+ to DMA + DMAH+ of 0.31 ± 0.16 (average ± standard deviation) at atmospheric NH3 concentrations over 1.8 µg m-3 (with a corresponding DMA/NH3 ratio of (1.8 ± 1.0) × 10-3), 0.80 ± 0.15 at atmospheric NH3 concentrations below 0.3 µg m-3 (with a corresponding DMA/NH3 ratio of (1.3 ± 0.6) × 10-2), and 0.56 ± 0.19 in the remaining cases. Particulate TMA concentrations, detected as TMAH+, ranged from <2 to 21 ng m-3 and decreased with increasing concentrations of atmospheric NH3. However, TMAH+ was depleted concurrently with the formation of NH4NO3 under low concentrations of atmospheric NH3, contradictory to the calculated increase in the equilibrated concentration of TMAH+ by the E-AIM.


Assuntos
Poluentes Atmosféricos , Amônia , Aerossóis/análise , Poluentes Atmosféricos/análise , Atmosfera , Dimetilaminas/análise , Monitoramento Ambiental , Gases/química , Metilaminas/análise , Material Particulado/análise
20.
BMC Med ; 20(1): 165, 2022 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-35468782

RESUMO

BACKGROUND: There is evidence indicating that pesticide exposure is a risk factor for non-Hodgkin lymphoma (NHL) development. However, the association between pesticide exposure and NHL survival is not well-established. METHODS: Using the California Cancer Registry, we identified patients with a first primary diagnosis of NHL from 2010 to 2016 and linked these patients with CalEnviroScreen 3.0 to obtain production agriculture pesticide exposure to 70 chemicals from the state-mandated Pesticide Use Reporting (PUR) by census tract from 2012 to 2014. In addition, data from PUR was integrated into a geographic information system that employs land-use data to estimate cumulative exposure to specific pesticides previously associated with NHL (glyphosate, organophosphorus, carbamate, phenoxyherbicide, and 2,4-dimethylamine salt) between 10 years prior up to 1 year after NHL diagnosis. Multivariable Cox proportional hazards regression models were used to evaluate the association between total pesticide exposure from CalEnviroScreen 3.0 and individual pesticide exposure from geographic land use data and lymphoma-specific and overall survival. RESULTS: Among 35,808 NHL patients identified, 44.2% were exposed to pesticide in their census tract of residence. Glyphosate, organophosphorus, carbamate, phenoxyherbicide, and 2,4-dimethylamine salt exposure was observed in 34.1%, 26.0%, 10.6%, 14.0%, and 12.8% of NHL patients, respectively. Total pesticide exposure at the time of diagnosis was not associated with lymphoma-specific or overall survival. In addition, no association was consistently found between glyphosate, organophosphorus, carbamate, phenoxyherbicide, and 2,4 dimethylamine salt exposure and lymphoma-specific or overall survival. CONCLUSIONS: Although we found no consistent associations between agricultural pesticide exposure at the neighborhood level and worse survival, these results provide a platform for designing future studies to determine the association between pesticide and NHL.


Assuntos
Linfoma não Hodgkin , Praguicidas , Carbamatos , Estudos de Casos e Controles , Dimetilaminas , Humanos , Linfoma não Hodgkin/induzido quimicamente , Linfoma não Hodgkin/epidemiologia , Praguicidas/efeitos adversos
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