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1.
Food Res Int ; 178: 113980, 2024 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-38309883

RESUMEN

Incorporation of two sesame cake preparations, differing in fat, 11 % (LF) and 17 % (HF), and protein, 51 % (LF) and 44 % (HF), contents, respectively, into breads at 6, 12 and 20 % wheat flour substitution levels, led to enriched end-products with antioxidants, suitable also to carry the 'high protein' and 'fiber source' nutrition claims (at ≥ 12 % substitution level). Sesame cake decreased wheat dough resistance to mixing and extension, and peak viscosity (empirical rheology), in a concentration-dependent manner, being more pronounced for LF formulations. Breads with LF incorporation ≥ 12 % had lower specific volumes and harder crumb (texture analysis) throughout storage, than control (100 % wheat flour); however, such adverse effects were diminished in HF bread formulations due to the plasticizing and emulsifying action of the sesame cake fat. Calorimetry showed that the sesame cake had no effect on starch retrogradation, but enhanced amylose-lipid complex formation. Antioxidant activity (ABTS, DPPH and FRAP assays), and phenolic acids (ferulic, p-coumaric and sinapic) and lignan (sesaminol glucosides and sesamolin) contents, determined by HPLC-DAD-MS, were higher in LF breads than their HF counterparts. The presence of some sulfur (off-flavor) and pyrazine (nutty flavor) compounds (SPME-GC-MS), as well as the sesame flavor and bitterness (sensory analysis) were of higher intensity in HF breads, while the 6 % LF product received the highest overall acceptability score among all fortified products. Overall, the sesame cake can be a promising ingredient for production of functional wheat bread depending on its composition and fortification level.


Asunto(s)
Antioxidantes , Sesamum , Antioxidantes/análisis , Pan/análisis , Triticum/química , Harina/análisis
2.
J Sci Food Agric ; 103(8): 4184-4194, 2023 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-36628517

RESUMEN

BACKGROUND: Oleogels can be used in the food industry to reduce the consumption of solid fat in the human diet and diminish some of the industrial-technological issues of using oil instead of fat. Regarding the structural weakness of neat monoglyceride oleogel and the waxy mouthfeel of pure carnauba wax oleogel, as a result of the high melting and crystallization points, the present study aimed to diminish these defects. RESULTS: Carnauba wax (CBW) was used as a co-gelator with distilled monoglyceride (DMG) at different weight ratios (100:0, 85:15, 70:30, 55:45, 40:60, and 0:100) (DMG: CBW) and two total gelator concentrations (50 and 100 g kg-1 ) to improve the DMG oleogel characteristics. The addition of CBW strengthened the DMG network and decreased the polymorphic transition. Thermal analysis showed just co-crystallization at the 85:15 ratio, whereas, in the other combinations, high melting components of CBW crystalized at first. As a result of the crystal homogeneity and long-time development, the oleogel properties improved at the 85:15 ratio. The low concentration of CBW and the formation of the eutectic system were efficient in the waxy mouthfeel reduction of oleogel at the 85:15 ratio in food applications. CONCLUSION: The DMG/CBW oleogel at the 85:15 ratio, with better structural and sensorial properties than DMG and CBW oleogels, respectively, has the potential for use instead of fat in food formulations. © 2023 Society of Chemical Industry.


Asunto(s)
Monoglicéridos , Ceras , Humanos , Ceras/química , Compuestos Orgánicos/química , Glicéridos/química
3.
Environ Sci Pollut Res Int ; 30(4): 10110-10127, 2023 Jan.
Artículo en Inglés | MEDLINE | ID: mdl-36070038

RESUMEN

Biomass energy contributes nearly 14% of the total global energy. Therefore, biomass briquettes can be effectively considered an alternate source of fossil fuels. The present study aims at utilizing Senna auriculata and Ricinus communis waste generated locally for the production of biomass briquettes with 10% of tapioca starch as binder. The biomass wastes are blended at various proportions such as 0:100 (S1), 25:75 (S2), 50:50 (S3), 75:25 (S4) and 100:0 (S5) respectively, and the concentration of binder was maintained to be constant. The characterization of the prepared biomass briquettes includes the analysis of physical characteristics, proximate analysis, elemental analysis, SEM analysis, thermogravimetric analysis, differential scanning calorimetric analysis and XRD analysis. The results of the proximate analysis have revealed that the biomass briquettes possess lower percentage in terms of moisture content, ash content, sensible fixed carbon and high percentage of volatile matter content. Energy dispersive X-ray analysis has shown that the carbon and oxygen are the major elements for all the biomass briquettes. SEM analysis has revealed that the surface of the biomass briquettes is identified with irregular surface, lumps, cavities and few deposits of carbon particles. Thermogravimetric analysis and DSC analysis have reconfirmed the spontaneous burning characteristics of biomass briquettes. XRD analysis has proved that the bonding between each element present in the biomass briquettes is either monoclinic, tetragonal, orthorhombic or anorthic.


Asunto(s)
Biocombustibles , Manihot , Biomasa , Carbono , Almidón
4.
Materials (Basel) ; 15(24)2022 Dec 07.
Artículo en Inglés | MEDLINE | ID: mdl-36556522

RESUMEN

To produce Na2SnO3, which is widely used in the ceramics and electroplating industries, a novel process for the preparation of sodium stannate from cassiterite concentrates was developed successfully by the authors' group. It was found that sodium stannosilicate (Na8SnSi6O18) was easily formed due to the main gangue of quartz in cassiterite concentrates, which was almost insoluble and decreased the quality of Na2SnO3. The formation and transitions of Na8SnSi6O18 in the SnO2-SiO2-Na2CO3 system roasted under a CO-CO2 atmosphere were determined. The results indicated that the formation of Na8SnSi6O18 could be divided into two steps: SnO2 reacted with Na2CO3 to form Na2SnO3, and then Na2SnO3 was rapidly combined with SiO2 and Na2CO3 to form low melting point Na8SnSi6O18. In addition, Na8SnSi6O18 can be decomposed into Na2SiO3 and Na2SnO3 by using excess Na2CO3.

5.
Polymers (Basel) ; 14(7)2022 Mar 28.
Artículo en Inglés | MEDLINE | ID: mdl-35406241

RESUMEN

Ever since the introduction of 3D printing, industries have seen an exponential growth in production and efficiency. Three-dimensional printing is the process of additive manufacturing (AM) in which the conventional method of material removal is challenged. Layer-on-layer deposition is the basic principle of the AM. Additive manufacturing technologies are used to create 3D-printed objects. An object is built in an additive technique by laying down successive layers of material until the object is complete. Each of these layers can be viewed as a cross-section of the item that has been lightly cut. When compared to traditional production methods, 3D printing allows the creation of complicated shapes with less material. In conventional methods, the materials go through several damages due to the tool-workpiece contact creating friction between them and the dissipated heat that damages the material. Overcoming the conventional method of machining with the help of 3D printing is a new advancement in the industries. The process involves using non-conventional methods for the machining of the parts. This research was oriented towards the chemical vapor jet drilling of the acrylonitrile-butadiene-styrene (ABS) materials. ABS materials are highly machinable and can be recycled for further usage. This paper focused on the usage of acetone as the chemical for drilling. The surface roughness and circularity of the drilled hole was taken into account for this research paper. We set up a manual experiment to run tests and get results. A vapor jet machine was designed with acetone as the core for the vapor. Various analyses were also formulated and conducted during experimentations. Surface roughness analysis provided the insight of roughness after the machining with the help of acetone vapor jet spray. SEM and micro-image parameters were also considered for more clear and advanced reports. In this research paper, DSC and FTIR analysis were performed to understand changes in the internal structure and the material properties of the ABS. Moreover, the research aimed to investigate the effect of various inputs processing parameters such as pressure, flow rate, and stand-off distance on the surface roughness and circularity of ABS workpiece material. The Taguchi L9 orthogonal array design was utilized to conduct tests by chemical vapor jet drilling using acetone and to evaluate the performance of the set-up while reducing the influence of interfering factors in order to provide reliable surface finish and circularity results. The results and conclusion of the research paper aimed to determine the most suitable parameters for the non-conventional acetone vapor jet drilling of the ABS material. The theoretical calculations predicted 1.64432 and 0.3289080 values of surface roughness and circularity, respectively. On the other hand, the experimental values were recorded as 1.598 for surface roughness and 0.322 for circularity. Therefore, a negligible error of 0.046 for surface roughness and 0.0031 for circularity, respectively, was noted which validate the statistical equations and the consistency of the combined vapor jet drilling process.

6.
Materials (Basel) ; 15(6)2022 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-35329760

RESUMEN

This study aimed to assess the developed nonwoven inserts with aerogel/PCM (phase change material) microcapsules for use in protective clothing against cold in terms of properties related to thermophysiological comfort. These inserts were obtained by the thermal bonding of a multilayer system consisting of needled-punched nonwovens and silica aerogel particles and/or PCM microcapsules evenly distributed between them. The influence of aerogel and PCM microcapsules on the basic physical properties of inserts, their microstructure, air permeability, and water vapor resistance was investigated and analyzed. The thermal insulation properties of inserts were assessed based on thermal conductivity results. The inserts with PCMs were also tested for their ability to regulate the temperature in the undergarment microclimate using the differential scanning calorimeter (DSC) and the "skin model" device. The research showed that the use of aerogel allowed for reducing the thermal conductivity of the insert by approximately 13% compared to the insert without additives. The high values obtained of the melting and crystallization enthalpy of inserts with PCMs confirmed their high efficiency in the heat absorption and release. Thus, the use of aerogel and PCMs in protective clothing against cold seems to be an effective solution for improving its protective properties and actively adapting its thermal insulation to the changing temperature conditions and the activity level of employees.

7.
Materials (Basel) ; 15(3)2022 Jan 19.
Artículo en Inglés | MEDLINE | ID: mdl-35160695

RESUMEN

In this study, we investigated the impact of reaction temperature on the physicochemical, structural, morphological, and thermal properties of sodium alginate/poly (vinyl alcohol)-based hydrogels, both in the pure form and with the addition of 20% (v/v) Aloe vera solution. The materials were prepared by chemical crosslinking at temperatures in the range of 65-75 °C. Poly (ethylene glycol) diacrylate was used as a crosslinking agent. The extent to which the crosslinking reaction proceeded was studied as a function of the reaction temperature, along with the thermal properties and morphology of the final materials. A measurement of gel fraction, in agreement with differential scanning calorimetry and Fourier transform infrared spectroscopy, showed that a higher temperature of reaction promoted the crosslinking reaction. On the basis of the aforementioned techniques, as well as by energy dispersive X-ray analysis under an electron microscope, it was also shown that the bioadditive Aloe vera promoted the crosslinking reaction.

8.
Membranes (Basel) ; 11(8)2021 Aug 20.
Artículo en Inglés | MEDLINE | ID: mdl-34436403

RESUMEN

The polylactic acid (PLA) resin Ingeo 4032D was selected as the research object. Epoxy soybean oil (ESO) and zeolite (3A molecular sieve) were used as plasticizer and reinforcing filler, respectively, for PLA blend modification. The mixture was granulated in an extruder and then blown to obtain films under different conditions to determine the optimum processing temperatures and screw rotation. Then, the thermal behaviour, crystallinity, optical transparency, micro phase structure and physical properties of the film were investigated. The results showed that with increasing zeolite content, the crystallization behaviour of PLA changed, and the haze of the film increased from 5% to 40% compared to the pure PLA film. Zeolite and ESO dispersed in the PLA matrix played a role in toughening and strengthening. The PLA/8 wt% zeolite/3 wt% ESO film had the highest longitudinal tensile strength at 77 MPa. The PLA/2 wt% zeolite/3 wt% ESO film had the highest longitudinal elongation at 13%. The physical properties depended heavily on the dispersion of zeolite and ESO in the matrix.

9.
Materials (Basel) ; 14(14)2021 Jul 08.
Artículo en Inglés | MEDLINE | ID: mdl-34300742

RESUMEN

The paper presents a comparative analysis of the circular and flat cross-section belts using measurements of a set of thermomechanical parameters, contributing to research about hot plate welding of drive belts. On the basis of thermogravimetric and spectrophotometric tests, information about the same chemical composition of the two belts was obtained. Dynamic thermomechanical analysis and scanning differential calorimetry provided information about a small difference between belts, which disappeared when the material was placed in a state of increased temperature and mechanical stress. On the basis of the analysis of the specific heat, thermal diffusion, density, and hardness, the values of the selected thermal properties of the belt were obtained, and a large similarity between the belts was identified. On the basis of the novel performed test cycle, it has been hypothesized that circular and flat belts made from thermoplastic polyurethane elastomer could be used interchangeably for butt-welding testing. It has also been proven that cyclic thermomechanical loads unify the properties of both materials so that multiple mechanical and thermal loads do not result in any change in the material properties of the two belts. As a consequence, changes in the weld properties after welding, compared to a solid belt, are not expected.

10.
J Environ Manage ; 290: 112487, 2021 Jul 15.
Artículo en Inglés | MEDLINE | ID: mdl-33873020

RESUMEN

This paper presents the possibility of valorization of animal manure (camel and cow) by mixing it with agro-industrial biomass (cotton stalk and rapeseed oil cake) to produce pellets for use in power generation processes. Feedstocks were mixed in specific proportions based on certain assumptions concerning the energy and mechanical parameters of pellets. The assessment concerned both the combustion behavior as well as mechanical properties of four types of pellets derived from blends of animal manure and agro-industrial biomass. Thermogravimetry (TGA) and Differential Scanning Calorimetry (DSC) techniques are applied to analyze the reaction areas, characteristic temperatures as well as heat flow rates of raw materials and their blends. Results showed that addition of agro-industrial biomass (even 10%) to animal manure changed the specific combustion parameters: initiation and burn-out temperature and combustion time. For blends of cow manure (COM) and rapeseed oil cake (ROC), a reduction in the initiation temperature was achieved compared to the combustion of raw cow manure, and the combustion time increased by 1/3. In the case of camel manure (CAM) with the addition of cotton stalk (CS) the burn-out temperature and combustion time decreased. The addition of agro-biomass also causes a change in the heat release profiles, for the blends no pronounced DSC peaks are obtained in the area of devolatilization as it happens animal manure alone and in the area of fixed carbon combustion as for cotton stalk and rapeseed oil cake. The heat released from camel manure blends was 9.2-9.3 kJ/kg and from cow manure blends 10.2-10.4 kJ/kg. An evaluation of the physical and mechanical properties showed that all types of pellets at a moisture content of 10-15% have a similar drop strength in the range of 80-85%, while this strength decreases to 40-60% after the pellets have absorbed water.


Asunto(s)
Lignina , Estiércol , Animales , Biomasa , Termogravimetría
11.
Acta Crystallogr C Struct Chem ; 77(Pt 2): 90-99, 2021 Feb 01.
Artículo en Inglés | MEDLINE | ID: mdl-33536372

RESUMEN

Two new metal coordination complexes, namely, poly[aqua(µ6-benzene-1,2,4,5-tetracarboxylic acid-κ8O1:O1,O2:O2':O4:O4,O5:O5')(µ-but-2-enedioato-κ2O1:O4)potassium(I)], [K2(C4H2O4)(C10H6O8)(H2O)2]n or [K2(fum)(H4btec)(H2O)2]n, (1), and poly[aqua(µ8-2,5-dicarboxybenzene-1,4-dicarboxylato-κ12O1:O1',O2:O2,O2':O2':O4:O4',O5:O5,O5':O5')(µ-ethanedioato-κ4O1,O2:O1',O2')strontium(II)], [Sr2(C2O4)(C10H4O8)(H2O)2]n or [Sr2(ox)(H2btec)(H2O)2]n, (2) (H4btec = benzene-1,2,4,5-tetracarboxylic acid, H2btec = 2,5-dicarboxybenzene-1,4-dicarboxylate, fum = fumarate and ox = oxalate), have been obtained under hydrothermal conditions by reacting the different alkali and alkaline earth metal salts with H4btec, fumaric acid (H2fum) and oxalic acid (H2ox). Complexes (1) and (2) were structurally characterized by single-crystal X-ray diffraction, IR and UV-Vis spectroscopy, powder X-ray diffraction (PXRD) and thermogravimetic analysis-differential scanning calorimetry (TGA-DSC). Complex (1) displays a two-dimensional (2D) layer with the K+ ion in a distorted pentagonal bipyramidal geometry and exhibits a uninodal 6-connected hxl/Shubnikov plane net (3,6) with {36.46.53} topology. Complex (2) displays a three-dimensional (3D) network structure, in which the Sr2+ ion is in a distorted monocapped square antiprism geometry. The framework possess a binodal (5,8)-connected net with the Schläfli symbol {32.410.58.64.74}{32.46.52}2. The 3D Hirshfeld surfaces and 2D fingerprint plots show that the main interactions are the O...H/H...O intermolecular interactions. Moreover, the thermal decompositions of (1) and (2) in the temperature range 303-1273 K revealed that they both decompose in three steps and transform to the corresponding metal oxide.

12.
Environ Sci Pollut Res Int ; 28(17): 21471-21485, 2021 May.
Artículo en Inglés | MEDLINE | ID: mdl-33415632

RESUMEN

The utilization of agricultural wastes is an attractive and viable option to reduce the environmental pollution and reverse the over-exploitation of fossil fuels. Now-a-days, the usage of fossil fuels has increased manifold causing twin serious problems such as depletion of limited source of fossil fuels and increase in environmental pollution with major consequences. In this study, briquettes were produced using sorghum panicles (SP) and pearl millet (PM) with different ratios (100:0, 10:90, 20:80, 30:70, 40:60, 50:50, 60:40, 70:30, 80:20, 90:10 and 0:100) using cassava starch as a binder with a planned compacting pressure level (200 kN) by exploring hydraulic compression method. The proximate parameters such as water content, level of fixed carbon, ash and volatile matter were determined using American Society for Testing and Materials (ASTM) standard procedures. The elemental analyses (SEM/EDAX) which include carbon (C), oxygen (O), potassium (K), calcium (Ca), chlorine (Cl), sulphur (S), phosphorus (P), aluminium (Al), silicon (Si), magnesium (Mg), cobalt (Co), iron (Fe), zinc (Zn) and sodium (K) were determined in all the briquette samples. Weight loss and optimum heating values of the samples were measured by adopting differential scanning calorimetry (DSC) and thermogravimetric analysis (TGA) respectively. In addition to that, the density and compressive strength of all the produced briquettes were determined. In comparison with pongamia-tamarind shell, sorghum panicle-pearl millet briquettes have better fuel properties. The pongamia-tamarind shell fuel has nitrogen and hydrogen whereas sorghum panicle-pearl millet has no identities on both nitrogen and hydrogen content. The occurrence of nitrogen absence is due to non-availability of NOx emissions during combustion. By the cause of more fixed carbon composition, there exists lack in hydrogen content. The sorghum panicle-pearl millet briquettes have better calorific value than pongamia-tamarind shells, and they produce better heating values. Hence, the prepared biomass briquettes are potentially good fuels that derived from agro wastes. Likewise, the determined parameters are compared with the other biomass briquettes.


Asunto(s)
Manihot , Pennisetum , Sorghum , Carbono , Almidón
13.
Int J Mol Sci ; 21(18)2020 Sep 21.
Artículo en Inglés | MEDLINE | ID: mdl-32967166

RESUMEN

Achieving high thermal stability and control of supramolecular organization of functional dyes in sensors and nonlinear optics remains a demanding task. This study was aimed at the evaluation of thermal behavior and Langmuir monolayer characteristics of topologically varied nitrothiacalixarene multichromophores and phenol monomers. A nitration/azo coupling alkylation synthetic route towards partially O-substituted nitrothiacalixarenes and 4-nitrophenylazo-thiacalixarenes was proposed and realized. Nuclear magnetic resonance (NMR) spectroscopy and X-ray diffractometry of disubstituted nitrothiacalix[4]arene revealed a rare 1,2-alternate conformation. A synchronous thermal analysis indicated higher decomposition temperatures of nitrothiacalixarene macrocycles as compared with monomers. Through surface pressure/potential-molecular area measurements, nitrothiacalixarenes were shown to form Langmuir monolayers at the air-water interface and, through atomic force microscopy (AFM) technique, Langmuir-Blodgett (LB) films on solid substrates. Reflection-absorption spectroscopy of monolayers and electronic absorption spectroscopy of LB films of nitrothiacalixarenes recorded a red-shifted band (290 nm) with a transition from chloroform, indicative of solvatochromism. Additionally, shoulder band at 360 nm was attributed to aggregation and supported by gas-phase density functional theory (DFT) calculations and dynamic light scattering (DLS) analysis in chloroform-methanol solvent in the case of monoalkylated calixarene 3. Excellent thermal stability and monolayer formation of nitrothiacalixarenes suggest their potential as functional dyes.


Asunto(s)
Membranas Artificiales , Fenoles/química , Adsorción , Conformación Molecular
14.
Turk J Chem ; 44(6): 1483-1494, 2020.
Artículo en Inglés | MEDLINE | ID: mdl-33488246

RESUMEN

A humic substance was obtained from hazelnut husk using an alkali extraction. The chemical and morphological structure of the humic matter was characterized via elemental analysis, Fourier transform infrared spectrometry (FTIR), nuclear magnetic resonance, Brunauer-Emmet-Teller (BET) analysis, scanning electron microscopy (SEM), and thermogravimetric-FTIR (TG-FTIR). In addition, thermal analysis measurements TG analysis-differential thermogravimetry/differential scanning calorimetry (TGA-DTG/DSC) were performed under dynamic air conditions to better determine the origin, physical and chemical structure, and decomposition process of the humic matter. The Kissinger-Akahira-Sunose (KAS) and Flynn-Wall-Ozawa (FWO) methods were used to calculate the kinetic parameters of the high-temperature decomposition process. It was observed that the activation energy values were almost constant at certain conversion and temperature intervals. In addition, the structure of the humic substance at different temperatures was also investigated via FTIR analysis. It was found that the obtained humic substance had a very stable structure and decomposed at a high temperature. The stability of the humic matter can be a useful tool in the environmental quality research of soil.

15.
Eur Biophys J ; 48(7): 645-657, 2019 Oct.
Artículo en Inglés | MEDLINE | ID: mdl-31309277

RESUMEN

The DNA/RNA-binding KIN protein was discovered in 1989, and since then, it has been found to participate in several processes, e.g., as a transcription factor in bacteria, yeasts, and plants, in immunoglobulin isotype switching, and in the repair and resolution of double-strand breaks caused by ionizing radiation. However, the complete three-dimensional structure and biophysical properties of KIN remain important information for clarifying its function and to help elucidate mechanisms associated with it not yet completely understood. The present study provides data on phylogenetic analyses of the different domains, as well as a biophysical characterization of the human KIN protein (HSAKIN) using bioinformatics techniques, circular dichroism spectroscopy, and differential scanning calorimetry to estimate the composition of secondary structure elements; further studies were performed to determine the biophysical parameters ΔHm and Tm. The phylogenetic analysis indicated that the zinc-finger and winged helix domains are highly conserved in KIN, with mean identity of 90.37% and 65.36%, respectively. The KOW motif was conserved only among the higher eukaryotes, indicating that this motif emerged later on the evolutionary timescale. HSAKIN has more than 50% of its secondary structure composed by random coil and ß-turns. The highest values of ΔHm and Tm were found at pH 7.4 suggesting a stable structure at physiological conditions. The characteristics found for HSAKIN are primarily due to its relatively low composition of α-helices and ß-strands, making up less than half of the protein structure.


Asunto(s)
Proteínas de Unión al ADN/química , Proteínas de Unión al ADN/metabolismo , Filogenia , Proteínas de Unión al ARN/química , Proteínas de Unión al ARN/metabolismo , Fenómenos Biofísicos , Disulfuros/química , Regulación de la Expresión Génica , Humanos , Modelos Moleculares , Agregado de Proteínas , Estructura Secundaria de Proteína , Temperatura
16.
Mater Sci Eng C Mater Biol Appl ; 93: 776-781, 2018 Dec 01.
Artículo en Inglés | MEDLINE | ID: mdl-30274111

RESUMEN

A series of sugar-based glycolipid derivatives were prepared by N-glycosylamines, and their organogelation property has been analyzed. We have observed the efficient gelation for some of the anilines substituted glycolipids derivatives in different aromatic and aliphatic solvents. It was found that the gelation occurred predominantly in aliphatic solvents with CGC of 0.8% (w/v) attributed to the presence of long alkyl chain in the glycolipids. The structural and morphological properties of the xerogels were investigated by NMR, powder XRD, and FE-SEM respectively. Furthermore, the thermal stability was analyzed by DSC.


Asunto(s)
Glucosa/química , Glucolípidos/química
17.
Chirality ; 30(7): 943-950, 2018 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-29752740

RESUMEN

Several biologically active compounds structurally include the enantiopure 2-substituted-1,4-benzodioxane scaffold. The straightforward racemization that affects reactions involving most of the common chemical reactives is thus a crucial issue. The developing of a completely stereo-controlled synthetic route that does not affect the enantiomeric excess is consequently mandatory. It is also important to set up a reliable chiral HPLC method, able to follow the reaction, and to improve the synthetic performances. Here, we report the chiral investigation of two different synthons, we specifically evaluated the synthetic pathways that could be run in order to afford them, avoiding the racemization processes, which could normally occur in basic conditions. In addition, we developed peculiar chiral HPLC methods in order to resolve the enantiomers, define the enantiomeric excess, and fully characterize these compounds.

18.
FEBS J ; 284(24): 4233-4261, 2017 12.
Artículo en Inglés | MEDLINE | ID: mdl-29063699

RESUMEN

The 5-aminoimidazole-4-carboxamide ribonucleotide (AICAR) transformylase/inosine monophosphate (IMP) cyclohydrolase (ATIC) catalyzes final two steps of purine nucleotide de novo biosynthetic pathway. This study reports the characterization of ATIC from Staphylococcus lugdunensis (SlugATIC). Apart from kinetic analysis and a detailed biophysical characterization of SlugATIC, the role of ATIC in cell proliferation has been demonstrated for the first time. The purified recombinant SlugATIC and its truncated domains exist mainly in dimeric form was revealed in gel-filtration and glutaraldehyde cross-linking studies. The two activities reside on separate domains was demonstrated in kinetic analysis of SlugATIC and reconstituted truncated N-terminal IMP cyclohydrolase (IMPCHase) and C-terminal AICAR transformylase (AICAR TFase) domains. Site-directed mutagenesis showed that Lys255 and His256 are the key catalytic residues, while Asn415 substantially contributes to AICAR TFase activity in SlugATIC. The differential scanning calorimetry (DSC) analysis revealed a molten globule-like structure for independent N-terminal domain as compared with a relatively stable conformational state in full-length SlugATIC signifying the importance of covalently linked domains. Unlike reported crystal structures, the DSC studies revealed significant conformational changes on binding of leading ligand to AICAR TFase domain in SlugATIC. The cell proliferation activity of SlugATIC was observed where it promoted proliferation and viability of NIH 3T3 and RIN-5F cells, exhibited in vitro wound healing in NIH 3T3 fibroblast cells, and rescued RIN-5F cells from the cytotoxic effects of palmitic acid and high glucose. The results suggest that ATIC, an important drug target, can also be exploited for its cell proliferative properties.


Asunto(s)
Proteínas Bacterianas/fisiología , Transferasas de Hidroximetilo y Formilo/fisiología , Complejos Multienzimáticos/fisiología , Nucleótido Desaminasas/fisiología , Staphylococcus lugdunensis/enzimología , Aminoimidazol Carboxamida/análogos & derivados , Aminoimidazol Carboxamida/farmacología , Animales , Proteínas Bacterianas/química , Proteínas Bacterianas/genética , Proteínas Bacterianas/aislamiento & purificación , Rastreo Diferencial de Calorimetría , División Celular/efectos de los fármacos , Glucosa/toxicidad , Transferasas de Hidroximetilo y Formilo/química , Transferasas de Hidroximetilo y Formilo/genética , Transferasas de Hidroximetilo y Formilo/aislamiento & purificación , Inosina Monofosfato/farmacología , Ratones , Complejos Multienzimáticos/química , Complejos Multienzimáticos/genética , Complejos Multienzimáticos/aislamiento & purificación , Mutación , Células 3T3 NIH , Nucleótido Desaminasas/química , Nucleótido Desaminasas/genética , Nucleótido Desaminasas/aislamiento & purificación , Ácido Palmítico/toxicidad , Conformación Proteica , Dominios Proteicos , Ratas , Proteínas Recombinantes de Fusión/aislamiento & purificación , Proteínas Recombinantes de Fusión/metabolismo , Ribonucleótidos/farmacología , Staphylococcus lugdunensis/genética , Cicatrización de Heridas/efectos de los fármacos
19.
Acta Crystallogr C Struct Chem ; 71(Pt 4): 306-10, 2015 Apr.
Artículo en Inglés | MEDLINE | ID: mdl-25836291

RESUMEN

In the title coordination polymer, catena-poly[[bis[{1-[(1H-benzimidazol-2-yl-κN(3))methyl]-1H-tetrazole}zinc(II)]-bis(µ4-pentane-1,5-dioato-1:2:1':2'κ(4)O(1):O(1'):O(5):O(5'))] methanol disolvate], {[Zn(C5H6O4)(C9H8N6)]·CH3OH}n, each Zn(II) ion is five-coordinated by four O atoms from four glutarate ligands and by one N atom from a 1-[(1H-benzimidazol-2-yl)methyl]-1H-tetrazole (bimt) ligand, leading to a slightly distorted square-pyramidal coordination environment. Two Zn(II) ions are linked by four bridging glutarate carboxylate groups to generate a dinuclear [Zn2(CO2)4] paddle-wheel unit. The dinuclear units are further connected into a one-dimensional chain via the glutarate ligands. The bimt ligands coordinate to the Zn(II) ions in a monodentate mode and are pendant on both sides of the main chain. In the crystal, the chains are linked by O-H···O and N-H···O hydrogen bonds into a two-dimensional layered structure. Adjacent layers are further packed into a three-dimensional network through van der Waals forces. A thermogravimetric analysis was carried out and the photoluminescent behaviour of the polymer was investigated.

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