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1.
Molecules ; 26(16)2021 Aug 06.
Artigo em Inglês | MEDLINE | ID: mdl-34443346

RESUMO

A temperature dependence of saturated vapor pressure of isavuconazole (IVZ), an antimycotic drug, was found by using the method of inert gas-carrier transfer and the thermodynamic functions of sublimation were calculated at a temperature of 298.15 K. The value of the compound standard molar enthalpy of sublimation was found to be 138.1 ± 0.5 kJ·mol-1. The IVZ thermophysical properties-melting point and enthalpy-equaled 302.7 K and 29.9 kJ mol-1, respectively. The isothermal saturation method was used to determine the drug solubility in seven pharmaceutically relevant solvents within the temperature range from 293.15 to 313.15 K. The IVZ solubility in the studied solvents increased in the following order: buffer pH 7.4, buffer pH 2.0, buffer pH 1.2, hexane, 1-octanol, 1-propanol, ethanol. Depending on the solvent chemical nature, the compound solubility varied from 6.7 × 10-6 to 0.3 mol·L-1. The Hansen s approach was used for evaluating and analyzing the solubility data of drug. The results show that this model well-described intermolecular interactions in the solutions studied. It was established that in comparison with the van't Hoff model, the modified Apelblat one ensured the best correlation with the experimental solubility data of the studied drug. The activity coefficients at infinite dilution and dissolution excess thermodynamic functions of IVZ were calculated in each of the solvents. Temperature dependences of the compound partition coefficients were obtained in a binary 1-octanol/buffer pH 7.4 system and the transfer thermodynamic functions were calculated. The drug distribution from the aqueous solution to the organic medium was found to be spontaneous and entropy-driven.


Assuntos
Nitrilas/química , Piridinas/química , Temperatura , Triazóis/química , 1-Octanol/química , Varredura Diferencial de Calorimetria , Cristalização , Solubilidade , Solventes/química , Volatilização , Água/química
2.
Molecules ; 26(16)2021 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-34443422

RESUMO

A significant increase in the production of plastic materials and the expansion of their areas of application contributed to the accumulation of a large amount of waste of polymeric materials. Most of the polymer composition is made up of plasticizers. Phthalate plasticizers have been recognized as potentially hazardous to humans and the environment due to the long period of their biodegradation and the formation of persistent toxic metabolites. It is known that the industrial plasticizer dioctyl adipate is characterized by reduced toxicity and a short biodegradation period. The paper describes the synthesis of a number of new asymmetric esters based on adipic acid and ethoxylated butanol by azeotropic esterification. The receipt of the products was confirmed by IR spectra. The physicochemical properties of the synthesized compounds were investigated. The glass transition temperatures of PVC composites plasticized with alkyl butoxyethyl adipates were determined using DSC analysis. The ecological safety of esters was assessed by the phytotesting method. Samples of adipates were tested for fungal resistance, and the process of their biodegradation in soil was also studied. It is shown that the synthesized esters have good plasticizing properties and are environmentally safe. When utilized under natural conditions, they can serve as a potential source of carbon for soil microorganisms and do not form stable toxic metabolites; therefore, they are not able to accumulate in nature; when the plasticizers under study are disposed of in the soil, toxic substances do not enter.


Assuntos
Adipatos/toxicidade , Ecotoxicologia , Etanol/química , Plastificantes/toxicidade , Adipatos/síntese química , Adipatos/química , Biodegradação Ambiental , Varredura Diferencial de Calorimetria , Etanol/síntese química , Fungos/efeitos dos fármacos , Vidro/química , Lepidium/efeitos dos fármacos , Cloreto de Polivinila/química , Raphanus/efeitos dos fármacos , Solo , Espectrofotometria Infravermelho , Temperatura de Transição
3.
Int J Pharm ; 606: 120894, 2021 Sep 05.
Artigo em Inglês | MEDLINE | ID: mdl-34280485

RESUMO

Rheumatoid arthritis (RA) is a chronic autoimmune joint disorder that affects about 1% of the world population and may lead to severe disability and comorbidity. Despite breakthroughs in past decades to understand its pathogenesis and the development of transforming disease-modifying antirheumatic drugs, the symptoms of many patients are not substantially improved. Sinomenine (SIN), a natural alkaloid with poor solubility, has been used to treat RA in China for years because of its unique immunoregulative activity. However, its commercial hydrochloride form has a short half-time, which may cause huge fluctuations of blood drug concentration leading to severe adverse reactions. In this study, co-amorphous systems of SIN with three nonsteroidal anti-inflammatory drugs (NSAIDs), including indomethacin, naproxen, and sulindac, were prepared for the combination therapy, as well as the improvement of its aqueous solubility and controlled release. Each co-amorphous sample was characterized by powder X-ray diffraction (PXRD), temperature-modulated differential scanning calorimetry (mDSC), and Fourier transform infrared spectroscopy (FTIR). The CO2- and N+H stretching vibration in the three co-amorphous samples appears in FTIR spectra, suggesting the formation of salts between SIN and NSAIDs. SIN also exhibits sustained release rates in all three co-amorphous samples. These co-amorphous systems show excellent physicochemical stability because no recrystallization was observed at 25 °C and 75% relative humidity (RH) after four months. Our study suggests that SIN-NSAIDs co-amorphous systems represent an affordable and promising treatment against RA.


Assuntos
Anti-Inflamatórios não Esteroides , Artrite Reumatoide , Artrite Reumatoide/tratamento farmacológico , Varredura Diferencial de Calorimetria , Preparações de Ação Retardada , Combinação de Medicamentos , Estabilidade de Medicamentos , Humanos , Morfinanos , Solubilidade , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
4.
Int J Mol Sci ; 22(14)2021 Jul 09.
Artigo em Inglês | MEDLINE | ID: mdl-34299007

RESUMO

Ubiquitin fold modifier 1 (UFM1) is a member of the ubiquitin-like protein family. UFM1 undergoes a cascade of enzymatic reactions including activation by UBA5 (E1), transfer to UFC1 (E2) and selective conjugation to a number of target proteins via UFL1 (E3) enzymes. Despite the importance of ufmylation in a variety of cellular processes and its role in the pathogenicity of many human diseases, the molecular mechanisms of the ufmylation cascade remains unclear. In this study we focused on the biophysical and biochemical characterization of the interaction between UBA5 and UFC1. We explored the hypothesis that the unstructured C-terminal region of UBA5 serves as a regulatory region, controlling cellular localization of the elements of the ufmylation cascade and effective interaction between them. We found that the last 20 residues in UBA5 are pivotal for binding to UFC1 and can accelerate the transfer of UFM1 to UFC1. We solved the structure of a complex of UFC1 and a peptide spanning the last 20 residues of UBA5 by NMR spectroscopy. This structure in combination with additional NMR titration and isothermal titration calorimetry experiments revealed the mechanism of interaction and confirmed the importance of the C-terminal unstructured region in UBA5 for the ufmylation cascade.


Assuntos
Proteínas/química , Enzimas Ativadoras de Ubiquitina/química , Enzimas de Conjugação de Ubiquitina/química , Varredura Diferencial de Calorimetria , Expressão Gênica , Espectroscopia de Ressonância Magnética , Mutação , Peptídeos/química , Ligação Proteica , Domínios Proteicos , Proteínas/genética , Proteínas/metabolismo , Proteínas Recombinantes , Termodinâmica , Enzimas Ativadoras de Ubiquitina/genética , Enzimas Ativadoras de Ubiquitina/metabolismo , Enzimas de Conjugação de Ubiquitina/genética , Enzimas de Conjugação de Ubiquitina/metabolismo
5.
Waste Manag ; 131: 359-367, 2021 Jul 15.
Artigo em Inglês | MEDLINE | ID: mdl-34243095

RESUMO

Large amounts of by-products, including glauber's salt (GS) and microsilica (MS), are accumulated from chlor-alkali industry and ferrosilicon industry development, which not only wastes precious resources, but also causes serious environmental problems. In order to recycle and reuse these industrial by-products, solid sodium silicate was synthesized using GS and MS as the main raw materials, and semi-coke (SC) as the reducing agent. The effects of melting parameters including GS/SC and MS/GS molar ratio, heating rate, temperature, reaction time, and SC particle size on the conversion efficiency and modulus of solid sodium silicate were investigated and optimized. Under optimal conditions, the maximum conversion efficiency of 94.91% was obtained with modulus of 2.5. Characterization analysis of the products indicated that the amorphous silicate sodium was successfully synthesized. Moreover, the reaction mechanism was investigated, which focused on the thermal behavior and phase transformation using thermo-gravimetric and differential scanning calorimetric (TG-DSC) and in-situ X-ray diffraction. Additionally, the causes and suppression measures of "glauber's salt water" (GSW) during the experiment were summarized. This work not only creates resource utilization of GS and MS, but also provides the foundation for the synthesis of sodium silicate with GS.


Assuntos
Resíduos Industriais , Silicatos , Varredura Diferencial de Calorimetria , Termogravimetria , Difração de Raios X
6.
Int J Biol Macromol ; 185: 572-581, 2021 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-34216659

RESUMO

Chitosan microspheres (CMS) by the emulsion-chemical cross-linking method with and without lysozyme immobilization were synthesized and characterized. The technique conditions were adjusted, and spherical particles with approximate diameters of 3.74 ± 1.08 µm and 0. 29 ± 0.029 µm to CMS and chitosan-lysozyme microspheres (C-LMS), respectively, were obtained. The microspheres were characterized by scanning electron microscopy (FESEM), Spectroscopy Fourier Transform Spectroscopy (ATR-FTIR), X-ray diffraction (XRD), and zeta potential. Particle size was identified by laser light scattering (DLS) and the thermal properties by Differential Scanning Calorimetry (DSC) and Thermogravimetry (TGA) were determined. By the lysis of Micrococcus lysodeikticus, the activity of the microspheres was determined, and the results correlated with the amount of lysozyme used in the immobilization process and the enzyme loading efficiency was 67%. Finally, release tests pointed out the amount of enzyme immobilized on the microsphere surface. These results showed that chitosan microspheres could be used as material for lysozyme immobilization by cross-linking technique. The antimicrobial activity was tested by inhibition percent determination, and it evidenced both chitosan microspheres (CMS) and chitosan-lysozyme microspheres (C-LMS) positive antimicrobial activity to Staphylococcus aureus, Enterococcus faecalis and Pseudomonas aeruginosa.


Assuntos
Antibacterianos/farmacologia , Quitosana/farmacologia , Enterococcus faecalis/efeitos dos fármacos , Muramidase/química , Pseudomonas aeruginosa/efeitos dos fármacos , Staphylococcus aureus/efeitos dos fármacos , Antibacterianos/química , Varredura Diferencial de Calorimetria , Quitosana/química , Emulsões , Enzimas Imobilizadas/química , Microscopia Eletrônica de Varredura , Microesferas , Estrutura Molecular , Tamanho da Partícula , Propriedades de Superfície , Termogravimetria , Difração de Raios X
7.
Chem Pharm Bull (Tokyo) ; 69(7): 652-660, 2021.
Artigo em Inglês | MEDLINE | ID: mdl-34193714

RESUMO

The hydrocarbon-chain packing structure of intercellular lipids in the stratum corneum (SC) is critical to the skin's barrier function. We previously found that formation of V-shaped ceramide reduces the barrier function of skin. There are few agents, apart from ceramides and fatty acids that can improve the orthorhombic packing (Orth) ratio of the intercellular lipid packing structure. In this study, we investigated agents that directly increase the Orth ratio. We selected an intercellular lipid model consisting of ceramide, cholesterol, and palmitic acid and performed differential scanning calorimetry. We focused on natural moisturizing factor components in the SC, and therefore investigated amino acids and their derivatives. The results of our intercellular lipid model-based study indicate that N-acetyl-L-hydroxyproline (AHYP), remarkably, maintains the lamellar structure. We verified the effect of AHYP on the lamellar structure and hydrocarbon chain packing structure of intercellular lipids using time-resolved X-ray diffraction measurements of human SC. We also determined the direct physicochemical effects of AHYP on the Orth ratio of the hydrocarbon-chain packing structure. Hence, the results of our human SC study suggest that AHYP preserves skin barrier function by maintaining the hydrocarbon-chain packing structure of intercellular lipids via electrostatic repulsion. These findings will facilitate the development of skincare formulation that can maintain the skin's barrier function.


Assuntos
Aminoácidos/metabolismo , Absorção Cutânea , Acetilação , Aminoácidos/química , Varredura Diferencial de Calorimetria , Colesterol/química , Epiderme/química , Humanos , Hidroxiprolina/química , Hidroxiprolina/metabolismo , Bicamadas Lipídicas/química , Bicamadas Lipídicas/metabolismo , Nanoestruturas/química , Ácido Palmítico/química , Espalhamento a Baixo Ângulo , Difração de Raios X
8.
Int J Mol Sci ; 22(14)2021 Jul 08.
Artigo em Inglês | MEDLINE | ID: mdl-34298985

RESUMO

In this study, the temperature-dependent solubility of nicotinamide (niacin) was measured in six neat solvents and five aqueous-organic binary mixtures (methanol, 1,4-dioxane, acetonitrile, DMSO and DMF). It was discovered that the selected set of organic solvents offer all sorts of solvent effects, including co-solvent, synergistic, and anti-solvent features, enabling flexible tuning of niacin solubility. In addition, differential scanning calorimetry was used to characterize the fusion thermodynamics of nicotinamide. In particular, the heat capacity change upon melting was measured. The experimental data were interpreted by means of COSMO-RS-DARE (conductor-like screening model for realistic solvation-dimerization, aggregation, and reaction extension) for concentration dependent reactions. The solute-solute and solute-solvent intermolecular interactions were found to be significant in all of the studied systems, which was proven by the computed mutual affinity of the components at the saturated conditions. The values of the Gibbs free energies of pair formation were derived at an advanced level of theory (MP2), including corrections for electron correlation and zero point vibrational energy (ZPE). In all of the studied systems the self-association of nicotinamide was found to be a predominant intermolecular complex, irrespective of the temperature and composition of the binary system. The application of the COSMO-RS-DARE approach led to a perfect match between the computed and measured solubility data, by optimizing the parameter of intermolecular interactions.


Assuntos
Niacinamida/química , Termodinâmica , Acetonitrilas , Varredura Diferencial de Calorimetria , Cristalografia por Raios X , Dimerização , Dimetil Sulfóxido , Dimetilformamida , Dioxanos , Metanol , Modelos Químicos , Concentração Osmolar , Solubilidade , Soluções , Solventes , Espectrofotometria Infravermelho , Temperatura , Vibração , Água
9.
Int J Biol Macromol ; 185: 716-724, 2021 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-34217742

RESUMO

Chitosan-based hydrogels are a suitable and versatile system for the design of localized and controlled drug delivery systems. In the current study, a hydrogel based on chitosan (CS), Dopamine (DA), and Inulin aldehyde (IA) was fabricated without the further use of catalyst or initiators. The effect of the IA contents as a crosslinking agent on the properties of the prepared hydrogel was studied. The crosslinking reaction between CS and IA was verified by Fourier transform infrared spectroscopy (FTIR), thermogravimetric analysis (TGA), and differential scanning calorimetry (DSC). Various characteristics of the CS/DA/IA hydrogels were further assessed utilizing swelling experiment, in vitro drug release, in vitro cytotoxicity assay. The drug-loaded hydrogels represented the sustained release of Indomethacin according to the in vitro drug release test in acidic (pH = 4), basic (pH = 10) medium as well as physiological condition (pH = 7). Finally, the CS/DA/IA hydrogels exhibited appropriate cytocompatibility against the L-929 fibroblast cell line according to the direct contact MTT assay.


Assuntos
Quitosana/química , Dopamina/química , Fibroblastos/citologia , Indometacina/farmacologia , Inulina/química , Animais , Varredura Diferencial de Calorimetria , Sistemas de Liberação de Medicamentos , Fibroblastos/efeitos dos fármacos , Hidrogéis , Concentração de Íons de Hidrogênio , Indometacina/química , Camundongos , Microscopia Eletrônica de Varredura , Porosidade , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
10.
Int J Biol Macromol ; 185: 708-715, 2021 Aug 31.
Artigo em Inglês | MEDLINE | ID: mdl-34224756

RESUMO

Adding hydrocolloids into native starch is a secure and effective method of physical modification. In this study, the effect of sodium alginate (AG) on the gelatinization, rheological, and retrogradation properties of rice starch (RS) was investigated by measuring the pasting parameters, melting enthalpy (ΔH), rheological characteristic parameters, intensity ratio of 1047 cm-1 to 1022 cm-1 (R1047/1022), and relative crystallinity (RC) of RS-AG blends. Rapid visco analysis shows that AG could significantly change the gelatinization parameters of RS. Differential scanning calorimetry results show that the ΔH values of RS initially decreased in the low AG concentration range (0.10%-0.30%), but increased in the high AG concentration range (0.30%-0.50%). Dynamic rheological analysis reveals that the modulus (G', G'') and the loss tangent (tan δ) increased with the rise of the AG concentration from 0.10% to 0.50%. Fourier transform infrared spectroscopy and X-ray diffraction patterns collectively prove that the crystallinity of RS decreased with the addition of AG during the retrogradation periods. The interactions between AG and starch molecules in RS-AG blends were hypothesized to correlate with the aforementioned results.


Assuntos
Alginatos/química , Gelatina/química , Oryza/química , Varredura Diferencial de Calorimetria , Reologia , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
11.
Eur J Pharm Sci ; 165: 105955, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34298141

RESUMO

In the present study, a multi-component system comprised of dipalmitylphospatidylcholine (DPPC), Chitosan, Lactose, and L-Leucine was developed for pulmonary delivery. Microparticles were engineered by the spray drying process and the selection of the critical parameters was performed by applying experimental design. The microcarriers with the appropriate size and yield were co-formulated with two active pharmaceutical ingredients (APIs), namely, Formoterol fumarate and Budesonide, and they were further investigated. All formulations exhibited spherical shape, appropriate aerodynamic performance, satisfying entrapment efficiency, and drug load. Their physicochemical properties were evaluated using Scanning Electron Microscopy (SEM), Fourier Transform Infrared Spectroscopy (FT-IR), and Differential Scanning Calorimetry (DSC). The aerodynamic particle size characterization was determined using an eight-stage Andersen cascade impactor, whereas the release of the actives was monitored in vitro in simulated lung fluid. Additional evaluation of the microparticles' mucoadhesive properties was performed by ζ-potential measurements and ex vivo mucoadhesion study applying a falling liquid film method using porcine lung tissue. Cytotoxicity and cellular uptake studies in Calu-3 lung epithelial cell line were conducted to further investigate the safety and efficacy of the developed formulations.


Assuntos
Budesonida , Administração por Inalação , Animais , Varredura Diferencial de Calorimetria , Composição de Medicamentos , Fumarato de Formoterol , Microscopia Eletrônica de Varredura , Tamanho da Partícula , Espectroscopia de Infravermelho com Transformada de Fourier , Suínos
12.
Eur J Pharm Sci ; 165: 105958, 2021 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-34314840

RESUMO

The polymorphism of apremilast has been investigated. Two polymorphs have been identified and characterized by differential scanning calorimeter, fourier transform infrared spectroscopy, and powder X-ray diffractometer. Solubilities of apremilast forms B and E in three binary solvents of methanol-water, acetonitrile-water, and acetonitrile-methanol have been measured using the static method at a temperature ranging from 288.15 K to 328.15 K under standard atmospheric pressure. Subsequently, the solubility data have been analyzed using the Wilson, NRTL, and UNIQUAC thermodynamic models, respectively. Furthermore, the Gibbs energy of solution and the radial distribution function have been calculated using the molecular simulation method to evaluate the dissolution mechanism. The Gibbs energy of solution reveals that the rank of solute-solvent interaction correlated well with solubility order in binary solvent mixtures, and the radial distribution function indicates that weakening of solvent-solvent interaction led to an increase in solubility.


Assuntos
Solubilidade , Varredura Diferencial de Calorimetria , Solventes , Talidomida/análogos & derivados , Termodinâmica
13.
Nat Commun ; 12(1): 4375, 2021 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-34272366

RESUMO

DNMDP and related compounds, or velcrins, induce complex formation between the phosphodiesterase PDE3A and the SLFN12 protein, leading to a cytotoxic response in cancer cells that express elevated levels of both proteins. The mechanisms by which velcrins induce complex formation, and how the PDE3A-SLFN12 complex causes cancer cell death, are not fully understood. Here, we show that PDE3A and SLFN12 form a heterotetramer stabilized by binding of DNMDP. Interactions between the C-terminal alpha helix of SLFN12 and residues near the active site of PDE3A are required for complex formation, and are further stabilized by interactions between SLFN12 and DNMDP. Moreover, we demonstrate that SLFN12 is an RNase, that PDE3A binding increases SLFN12 RNase activity, and that SLFN12 RNase activity is required for DNMDP response. This new mechanistic understanding will facilitate development of velcrin compounds into new cancer therapies.


Assuntos
Nucleotídeo Cíclico Fosfodiesterase do Tipo 3/química , Peptídeos e Proteínas de Sinalização Intracelular/química , Piridazinas/química , Monofosfato de Adenosina/química , Varredura Diferencial de Calorimetria , Domínio Catalítico , Sobrevivência Celular/efeitos dos fármacos , Sobrevivência Celular/genética , Microscopia Crioeletrônica , Nucleotídeo Cíclico Fosfodiesterase do Tipo 3/genética , Endorribonucleases/química , Células HEK293 , Células HeLa , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Cinética , Espectrometria de Massas , Complexos Multienzimáticos/ultraestrutura , Mutação , Ligação Proteica , Conformação Proteica em alfa-Hélice , Multimerização Proteica , Piridazinas/farmacologia , Proteínas Recombinantes , Tetra-Hidroisoquinolinas/química
14.
Int J Mol Sci ; 22(12)2021 Jun 18.
Artigo em Inglês | MEDLINE | ID: mdl-34207146

RESUMO

Human phenylalanine hydroxylase (PAH) is a metabolic enzyme involved in the catabolism of L-Phe in liver. Loss of conformational stability and decreased enzymatic activity in PAH variants result in the autosomal recessive disorder phenylketonuria (PKU), characterized by developmental and psychological problems if not treated early. One current therapeutic approach to treat PKU is based on pharmacological chaperones (PCs), small molecules that can displace the folding equilibrium of unstable PAH variants toward the native state, thereby rescuing the physiological function of the enzyme. Understanding the PAH folding equilibrium is essential to develop new PCs for different forms of the disease. We investigate here the urea and the thermal-induced denaturation of full-length PAH and of a truncated form lacking the regulatory and the tetramerization domains. For either protein construction, two distinct transitions are seen in chemical denaturation followed by fluorescence emission, indicating the accumulation of equilibrium unfolding intermediates where the catalytic domains are partly unfolded and dissociated from each other. According to analytical centrifugation, the chemical denaturation intermediates of either construction are not well-defined species but highly polydisperse ensembles of protein aggregates. On the other hand, each protein construction similarly shows two transitions in thermal denaturation measured by fluorescence or differential scanning calorimetry, also indicating the accumulation of equilibrium unfolding intermediates. The similar temperatures of mid denaturation of the two constructions, together with their apparent lack of response to protein concentration, indicate the catalytic domains are unfolded in the full-length PAH thermal intermediate, where they remain associated. That the catalytic domain unfolds in the first thermal transition is relevant for the choice of PCs identified in high throughput screening of chemical libraries using differential scanning fluorimetry.


Assuntos
Fenilalanina Hidroxilase/química , Desnaturação Proteica , Dobramento de Proteína , Sítios de Ligação , Varredura Diferencial de Calorimetria , Domínio Catalítico , Humanos , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Fenilalanina Hidroxilase/isolamento & purificação , Fenilcetonúrias , Conformação Proteica , Desnaturação Proteica/efeitos dos fármacos , Dobramento de Proteína/efeitos dos fármacos , Estabilidade Proteica , Temperatura , Termodinâmica , Ureia/química
15.
Int J Mol Sci ; 22(12)2021 Jun 16.
Artigo em Inglês | MEDLINE | ID: mdl-34208782

RESUMO

This paper concerns the physicochemical properties of chitosan/phenolic acid thin films irradiated by ultraviolet radiation with wavelengths between 200 and 290 nm (UVC) light. We investigated the preparation and characterization of thin films based on chitosan (CTS) with tannic (TA), caffeic (CA) and ferulic acid (FA) addition as potential food-packaging materials. Such materials were then exposed to the UVC light (254 nm) for 1 and 2 h to perform the sterilization process. Different properties of thin films before and after irradiation were determined by various methods such as Fourier transform infrared spectroscopy (FTIR), scanning electron microscopy (SEM), atomic force microscopy (AFM), differential scanning calorimeter (DSC), mechanical properties and by the surface free energy determination. Moreover, the antimicrobial activity of the films and their potential to reduce the risk of contamination was assessed. The results showed that the phenolic acid improving properties of chitosan-based films, short UVC radiation may be used as sterilization method for those films, and also that the addition of ferulic acid obtains effective antimicrobial activity, which have great benefit for food packing applications.


Assuntos
Antibacterianos/química , Antibacterianos/farmacologia , Quitosana/química , Hidroxibenzoatos/química , Raios Ultravioleta , Aderência Bacteriana/efeitos dos fármacos , Varredura Diferencial de Calorimetria , Fenômenos Químicos , Fenômenos Mecânicos , Testes de Sensibilidade Microbiana , Microscopia de Força Atômica , Espectroscopia de Infravermelho com Transformada de Fourier
16.
Molecules ; 26(11)2021 Jun 05.
Artigo em Inglês | MEDLINE | ID: mdl-34198944

RESUMO

Single crystal of furazolidone (FZL) has been successfully obtained, and its crystal structure has been determined. Common and distinctive features of furazolidone and nitrofurantoin (NFT) crystal packing have been discussed. Combined use of QTAIMC and Hirshfeld surface analysis allowed characterizing the non-covalent interactions in both crystals. Thermophysical characteristics and decomposition of NFT and FZL have been studied by differential scanning calorimetry (DSC), thermogravimetric analysis (TG) and mass-spectrometry. The saturated vapor pressures of the compounds have been measured using the transpiration method, and the standard thermodynamic functions of sublimation were calculated. It was revealed that the sublimation enthalpy and Gibbs energy of NFT are both higher than those for FZL, but a gain in the crystal lattice energy of NFT is leveled by an entropy increase. The solubility processes of the studied compounds in buffer solutions with pH 2.0, 7.4 and in 1-octanol was investigated at four temperatures from 298.15 to 313.15 K by the saturation shake-flask method. The thermodynamic functions of the dissolution and solvation processes of the studied compounds have been calculated based on the experimental data. Due to the fact that NFT is unstable in buffer solutions and undergoes a solution-mediated transformation from an anhydrate form to monohydrate in the solid state, the thermophysical characteristics and dissolution thermodynamics of the monohydrate were also investigated. It was demonstrated that a combination of experimental and theoretical methods allows performing an in-depth study of the relationships between the molecular and crystal structure and pharmaceutically relevant properties of nitrofuran antibiotics.


Assuntos
Antibacterianos/química , Furazolidona/química , Nitrofurantoína/química , Antibacterianos/farmacocinética , Varredura Diferencial de Calorimetria , Cristalografia por Raios X , Teoria da Densidade Funcional , Furazolidona/farmacocinética , Espectrometria de Massas , Estrutura Molecular , Nitrofurantoína/farmacocinética , Solubilidade , Termodinâmica , Termogravimetria
17.
Molecules ; 26(11)2021 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-34199868

RESUMO

A large quantity of longan fruits (Dimocarpus longan Lour.) produced annually are processed into many products, one of which is black longan, from which the dried, dark-brown meat has been used medicinally in traditional medicine, while the starch-containing seeds are discarded. In this study, starch samples (BLGSs) were isolated from seeds of black longan fruits prepared using varied conditions. The in vitro digestibility was determined in comparison with those extracted from fresh (FLGS) and dried (DLGS) seeds. Scanning electron microscopy (SEM), X-ray diffraction (XRD), differential scanning calorimetry (DSC), and Fourier transform infrared (FTIR) spectroscopy were employed to evaluate the starch properties. The results showed that the yields of FLGS, DLGS, and BLGSs were 20%, 23%, and 16-22% w/w, respectively. SEM images showed starch granules of mixed shapes, with sizes up to 15 µm in all samples. XRD patterns confirmed an A-type crystallinity for FLGS and DLGS, with strong refraction peaks at 2θ = 15°, 17°, 18°, and 23°, while BLGSs also showed detectable peaks at 2θ = 10° and 21°, which suggested V-type structures. Thermal properties corroborated the changes by showing increases in peak gelatinization temperature (Tp) and enthalpy energy (ΔH) in BLGSs. The paste viscosity of BLGSs (5% w/w) decreased by 20-58% from that of FLGS. The FTIR peak ratio at 1045/1022 and 1022/995 cm-1 also indicated an increase in ordered structure in BLGSs compared to FLGS. The significant increase in the amounts of slowly digestible starch (SDS) and resistant starch (RS) in BLGSs compared to FLGS, especially at a prolonged incubation time of 20 (4.2×) and 30 days (4.1×), was proposed to be due to the heat-induced formation of starch inclusion with other components inside the seed during the black longan production process. Thus, black longan seed could be a new source of starch, with increased RS content, for potential use in the food and related industries.


Assuntos
Amido Resistente/análise , Sapindaceae/química , Amido/análise , Varredura Diferencial de Calorimetria , Dessecação , Microscopia Eletrônica de Varredura , Sementes/química , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
18.
Molecules ; 26(13)2021 Jun 23.
Artigo em Inglês | MEDLINE | ID: mdl-34201524

RESUMO

Some agroforestry residues such as orange and olive tree pruning have been extensively evaluated for their valorization due to its high carbohydrates content. However, lignin-enriched residues generated during carbohydrates valorization are normally incinerated to produce energy. In order to find alternative high added-value applications for these lignins, a depth characterization of them is required. In this study, lignins isolated from the black liquors produced during soda/anthraquinone (soda/AQ) pulping of orange and olive tree pruning residues were analyzed by analytical standard methods and Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (solid state 13C NMR and 2D NMR) and size exclusion chromatography (SEC). Thermal analysis (thermogravimetric analysis (TGA), differential scanning calorimetry (DSC)) and antioxidant capacity (Trolox equivalent antioxidant capacity) were also evaluated. Both lignins showed a high OH phenolic content as consequence of a wide breakdown of ß-aryl ether linkages. This extensive degradation yielded lignins with low molecular weights and polydispersity values. Moreover, both lignins exhibited an enrichment of syringyl units together with different native as well as soda/AQ lignin derived units. Based on these chemical properties, orange and olive lignins showed relatively high thermal stability and good antioxidant activities. These results make them potential additives to enhance the thermo-oxidation stability of synthetic polymers.


Assuntos
Antioxidantes/análise , Citrus sinensis/química , Lignina/química , Lignina/farmacologia , Olea/química , Fenóis/análise , Varredura Diferencial de Calorimetria , Cromatografia em Gel , Espectroscopia de Ressonância Magnética , Espectroscopia de Infravermelho com Transformada de Fourier , Termogravimetria
19.
Int J Mol Sci ; 22(13)2021 Jun 29.
Artigo em Inglês | MEDLINE | ID: mdl-34209889

RESUMO

Excessive misuse of antibiotics and antimicrobials has led to a spread of microorganisms resistant to most currently used agents. The resulting global threats has driven the search for new materials with optimal antimicrobial activity and their application in various areas of our lives. In our research, we focused on the formation of composite materials produced by the dispersion of titanium(IV)-oxo complexes (TOCs) in poly(ε-caprolactone) (PCL) matrix, which exhibit optimal antimicrobial activity. TOCs, of the general formula [Ti4O2(OiBu)10(O2CR')2] (R' = PhNH2 (1), C13H9 (2)) were synthesized as a result of the direct reaction of titanium(IV) isobutoxide and 4-aminobenzoic acid or 9-fluorenecarboxylic acid. The microcrystalline powders of (1) and (2), whose structures were confirmed by infrared (IR) and Raman spectroscopy, were dispersed in PCL matrixes. In this way, the composites PCL + nTOCs (n = 5 and 20 wt.%) were produced. The structure and physicochemical properties were determined on the basis of Raman microscopy, thermogravimetric analysis (TGA), differential scanning calorimetry (DSC), electron paramagnetic resonance spectroscopy (EPR), and UV-Vis diffuse reflectance spectroscopy (DRS). The degree of TOCs distribution in the polymer matrix was monitored by scanning electron microscopy (SEM). The addition of TOCs micro grains into the PCL matrix only slightly changed the thermal and mechanical properties of the composite compared to the pure PCL. Among the investigated PCL + TOCs systems, promising antibacterial properties were confirmed for samples of PCL + n(2) (n = 5, 20 wt.%) composites, which simultaneously revealed the best photocatalytic activity in the visible range.


Assuntos
Anti-Infecciosos/síntese química , Compostos Organometálicos/síntese química , Poliésteres/química , Titânio/química , Anti-Infecciosos/química , Anti-Infecciosos/farmacologia , Varredura Diferencial de Calorimetria , Catálise , Microscopia Eletrônica de Varredura , Compostos Organometálicos/química , Compostos Organometálicos/farmacologia , Processos Fotoquímicos , Espectroscopia de Infravermelho com Transformada de Fourier , Resistência à Tração , Difração de Raios X
20.
Spectrochim Acta A Mol Biomol Spectrosc ; 261: 120018, 2021 Nov 15.
Artigo em Inglês | MEDLINE | ID: mdl-34091357

RESUMO

This paper demonstrates the assessment of vibrational spectroscopy methods such as middle infrared, near infrared and Raman spectroscopy (FTIR, FT-NIR, Raman) for the identification of pseudopolymorphic forms of a model active pharmaceutical ingredient (API) - sodium naproxen (NpxNa). NpxNa, in the form of three different pseudopolymorphs, was investigated by methods dedicated for solid state characterization: DSC (differential scanning calorimetry), XPRD (powder X-ray diffraction), SEM (scanning electron microscopy) and Karl Fischer titration. Novelty in the results sourced in the usage of the method not applied so far to identify pseudopolymorphic forms of NpxNa, that is, FTIR and FT-NIR. Based on the obtained reproduceable results, various pseudopolymorphic forms were successfully evaluated. Spectroscopic data were correlated with DSC and XPRD results. It was concluded that the combination of band's variations visible on the spectra of pseudopolymorphic forms will allow to interpretate the results unequivocally in case of crucial stability tests of medicinal substance or during on-line pharmaceutical process development by FTIR, FT-NIR and Raman spectroscopy.


Assuntos
Naproxeno , Análise Espectral Raman , Varredura Diferencial de Calorimetria , Pós , Sódio , Espectroscopia de Infravermelho com Transformada de Fourier
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