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1.
Int J Mol Sci ; 23(17)2022 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-36077409

RESUMO

Composite materials very often provide new catalytic, optical or other physicochemical properties not observed for each component separately. Photofunctions in hybrid systems are an interesting topic of great importance for industry. This review presents the recent advances, trends and possible applications of photofunctions of hybrid systems composed of Schiff base metal complexes and metal or semiconductor (nano)materials. We focus on photocatalysis, sensitization in solar cells (DSSC-dye sensitized solar cell), ligand-induced chirality and applications in environmental protection for Cr(VI) to Cr(III) reduction, in cosmetology as sunscreens, in real-time visualization of cellular processes, in bio-labeling, and in light activated prodrug applications.


Assuntos
Complexos de Coordenação , Catálise , Metais/química , Bases de Schiff , Semicondutores
2.
Elife ; 112022 09 06.
Artigo em Inglês | MEDLINE | ID: mdl-36065640

RESUMO

Rhodopsins convert light into signals and energy in animals and microbes. Heliorhodopsins (HeRs), a recently discovered new rhodopsin family, are widely present in archaea, bacteria, unicellular eukaryotes, and giant viruses, but their function remains unknown. Here, we report that a viral HeR from Emiliania huxleyi virus 202 (V2HeR3) is a light-activated proton transporter. V2HeR3 absorbs blue-green light, and the active intermediate contains the deprotonated retinal Schiff base. Site-directed mutagenesis study revealed that E191 in TM6 constitutes the gate together with the retinal Schiff base. E205 and E215 form a PAG of the Schiff base, and mutations at these positions converted the protein into an outward proton pump. Three environmental viral HeRs from the same group as well as a more distantly related HeR exhibited similar proton-transport activity, indicating that HeR functions might be diverse similarly to type-1 microbial rhodopsins. Some strains of E. huxleyi contain one HeR that is related to the viral HeRs, while its viruses EhV-201 and EhV-202 contain two and three HeRs, respectively. Except for V2HeR3 from EhV-202, none of these proteins exhibit ion transport activity. Thus, when expressed in the E. huxleyi cell membranes, only V2HeR3 has the potential to depolarize the host cells by light, possibly to overcome the host defense mechanisms or to prevent superinfection. The neuronal activity generated by V2HeR3 suggests that it can potentially be used as an optogenetic tool, similarly to type-1 microbial rhodopsins.


Assuntos
Vírus Gigantes , Prótons , Animais , Transporte de Íons , Rodopsina/genética , Rodopsinas Microbianas/genética , Bases de Schiff
3.
J Inorg Biochem ; 236: 111975, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36055108

RESUMO

The electrochemical oxidation of anodic metal copper in a solution of the ligands N-[(5-tert-butyl-2-hydroxyphenyl)methylidine]-N'-tosylbenzene-1,2-diamine [H2L1] and N-[(3,5-di-tert-butyl-2-hydroxyphenyl)methylidine]-N'-tosylbenzene-1,2-diamine, [H2L2] afforded homoleptic [CuL] compounds or solvate [CuLS] complexes. The addition to the electrochemical cell of coligands (L') such as 2,2'-bipyridine (2-bpy), 4,4'-bipyridine(4-bpy) or 1,10-phenanthroline (phen) allowed the synthesis, in one step, of heteroleptic [CuLL'] compounds, namely [CuL1(H2O)] (1), [CuL1(2,2'-bpy)]⋅CH3CN (2), [CuL1(phen)]·H2O (3), [Cu2L12(4,4'-bpy)] (4), [CuL2(CH3OH)] (5), [CuL2(2,2'-bpy)] (6), [CuL2(phen)] (7) and [Cu2L22(4,4'-bpy)] (8). The crystal structures of both ligands, H2L1, H2L2, and those of the complexes (2), (4), (5), (6) and (7) have been determined by X-ray diffraction techniques. Coordination polyhedron around metal atom is square planar for [CuL2(CH3OH)] (5) and [Cu2L12(4,4'-bpy)] (4) and square pyramid for the other complexes with additional chelating ligands. The cytotoxic activity of this new series of copper(II) complexes against the SH-SY5Y neuroblastoma cell line and U87-MG and U373-MG glioblastoma cell lines has been investigated. Most of the test compounds showed higher activity than cisplatin in the three cell lines. Among this series, compound [CuL1(phen)] (3) displayed the highest activity with IC50 equal to 1.77 µM on SH-SY5Y whereas compound [Cu2L12(4.4'-bpy)] (4) resulted the most potent compounds on U87 MG and U373 MG glioblastoma cell lines. Studies on the cytotoxic activity of these derivatives suggest that these compounds induce cell death by a mechanism other than apoptosis.


Assuntos
Antineoplásicos , Complexos de Coordenação , Glioblastoma , Neuroblastoma , 2,2'-Dipiridil , Antineoplásicos/química , Antineoplásicos/farmacologia , Cisplatino , Complexos de Coordenação/química , Complexos de Coordenação/farmacologia , Cobre/química , Cristalografia por Raios X , Diaminas/farmacologia , Humanos , Ligantes , Fenantrolinas/química , Fenantrolinas/farmacologia , Bases de Schiff/química , Bases de Schiff/farmacologia
4.
PLoS One ; 17(9): e0274123, 2022.
Artigo em Inglês | MEDLINE | ID: mdl-36084104

RESUMO

A new aldehyde 2,2'-[propane-1,3-diylbis(oxy)] dibenzaldehyde was synthesized from refluxing 2-hydroxy acetophenone and 2-hydroxy 1,3-dichloropropanean in an alcoholic medium. The compositions and properties of the new aldehyde compound were characterized by elemental analysis, FTIR, and nuclear magnetic resonance spectroscopy studies. The extracted chitosan was made to react with a new aldehyde to form a Schiff base by a suitable method. The effects of initial concentration of metal ions, exposure time, imine weight, and pH on the adsorption of Cu(II), Cr(III), and Zn(II) metal ions were examined. An adsorption batch experiment was conducted. The adsorption process followed a second-order reaction and Langmuir model with qe 25 mg/g, 121 mg/g, and 26.31 mg/g for Cu(II), Zn(II), and Cr(III) respectively. The Gibbs free energy showed a negative value and the adsorption/desorption tests provided a high value 5 times.


Assuntos
Quitosana , Metais Pesados , Poluentes Químicos da Água , Adsorção , Aldeídos , Quitosana/química , Concentração de Íons de Hidrogênio , Íons/química , Cinética , Metais Pesados/química , Bases de Schiff/química , Espectroscopia de Infravermelho com Transformada de Fourier , Poluentes Químicos da Água/química
5.
J Inorg Biochem ; 236: 111983, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36087436

RESUMO

Three di-organotin(IV) complexes have been synthesized by the reaction of Schiff base di-acylhydrazone ligands bis(5-chlorosalicylaldehyde) adipoylhydrazone and R2SnCl2 [R = Me (1), Ph (2), n-Bu (3)]. Structures of all complexes were characterized by 1H, 13C, 119Sn NMR, elemental analysis, IR and mass spectrometry. Experimental results showed that the symmetric diacylhydrazone ligands coordinate the tin atom in a hexadentate form, where the tin atom shows a penta-coordination, in a distorted triangular bipyramid geometry. Using MTT method, in vitro cytotoxicity of three complexes was determined against three cancer cell lines (A549, HeLa, HepG-2). Studies reveal that complex 3 showed the strongest cytotoxic activity among the three complexes, which may be correlated with the generation of intracellular reactive oxygen species. Uptake of complex 3 into cells and promotion of reactive oxygen species were visualized by confocal fluorescence imaging.


Assuntos
Compostos Orgânicos de Estanho , Bases de Schiff , Humanos , Ligantes , Compostos Orgânicos de Estanho/química , Compostos Orgânicos de Estanho/farmacologia , Espécies Reativas de Oxigênio/metabolismo , Bases de Schiff/química , Bases de Schiff/farmacologia , Estanho/química
6.
ACS Appl Mater Interfaces ; 14(37): 41726-41741, 2022 Sep 21.
Artigo em Inglês | MEDLINE | ID: mdl-36089750

RESUMO

The on-demand replacement of multifunctional hydrogel wound dressings helps to avoid bacterial colonization, and the on-demand painless peeling of tissue adhesive hydrogels on the wound site remains a major challenge to be solved. In this work, we design and develop a series of multifunctional dynamic Schiff base network hydrogels composed of cystamine-modified hyaluronic acid, benzaldehyde-functionalized poly(ethylene glycol)-co-poly(glycerol sebacate), and polydopamine@polypyrrole nanocomposite (PDA@PPy) with mild on-demand removability to enhance drug-resistant bacteria-infected wound healing. These hydrogels exhibited ideal injectable and self-healing properties, excellent tissue adhesion, in vivo hemostasis, good antioxidation, and conductivity. PDA@PPy inspired by melanin endows hydrogels with excellent antioxidant capacity, UV-blocking ability, and photothermal anti-infection ability. Based on the dynamic oxidation-reduction response of disulfide bonds inspired by the dissociation of the tertiary spatial structure transformation of poly-polypeptide chains, these hydrogels can achieve rapid painless on-demand removal under mild conditions by adding dithiothreitol. These multifunctional hydrogels significantly promoted collagen deposition and angiogenesis in the MRSA-infected full-thickness skin repair experiment. All the results showed that these multifunctional hydrogels with painless on-demand removal property showed great potential in clinical treatment of infected wounds.


Assuntos
Polímeros , Adesivos Teciduais , Antibacterianos/química , Antibacterianos/farmacologia , Antioxidantes/química , Bactérias , Bandagens , Benzaldeídos , Colágeno , Cistamina , Decanoatos , Dissulfetos , Ditiotreitol , Glicerol/análogos & derivados , Humanos , Ácido Hialurônico , Hidrogéis/química , Hidrogéis/farmacologia , Melaninas , Polietilenoglicóis , Polímeros/farmacologia , Pirróis , Bases de Schiff , Aderências Teciduais , Cicatrização
7.
J Inorg Biochem ; 236: 111961, 2022 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-36049258

RESUMO

Due to the growing prevalence of cancer diseases, new therapeutic options are urgently needed, and drugs based on metal ions other than platinum are alternatives with exciting possibilities. We report the synthesis, characterization and biological effect of mixed-ligand Fe(III)-aminophenolate complexes derived from salicylaldehyde and L-tryptophan with quinoline derivatives as co-ligands, namely 8-hydroxyquinoline (8HQ), [Fe(L)(8HQ)(H2O)] (1) and its 5-cloro derivative (Cl8HQ), [Fe(L)(Cl8HQ)(H2O)] (2). The complex bearing the aminophenolate and lacking the quinoline co-ligand, [Fe(L)(Cl)(H2O)2] (3), was prepared for comparison. The analytical and spectroscopic characterization revealed that 1 and 2 are octahedral Fe(III) complexes with the aminophenolate acting as a dianionic tridentate ligand and 8HQ co-ligands as bidentate chelates. Spectroscopic techniques and molecular docking studies were used to evaluate the ability of these complexes to bind bovine serum albumin (BSA) and calf thymus DNA. Complex 2 [Fe(L)(Cl8HQ)(H2O)] was the one showing higher affinity for both biomolecules. Cell viability was assessed in breast, colorectal and bone human cancer cell lines. 1 and 2 were found to be more active than cisplatin in all cell lines tested. A non-tumoral fibroblast line (L929, mouse non-tumoral fibroblasts) was used to evaluate selectivity. The results evidence that 2 shows much higher selectivity than 1 in all cell lines tested, but particularly in bone cancer cells in which selectivity index (SI) values are 8.0 and 18.8 for 1 and 2, respectively.


Assuntos
Antineoplásicos , Complexos de Coordenação , Animais , Antineoplásicos/química , Antineoplásicos/farmacologia , Cisplatino , Complexos de Coordenação/química , Complexos de Coordenação/farmacologia , Compostos Férricos , Humanos , Ligantes , Camundongos , Simulação de Acoplamento Molecular , Oxiquinolina/farmacologia , Platina , Bases de Schiff/química , Bases de Schiff/farmacologia , Soroalbumina Bovina/metabolismo , Triptofano
8.
Methods ; 206: 69-76, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-36049704

RESUMO

The detection of albumin proteins with high accuracy by facile analytical approaches is important for the diagnosis of various diseases. This manuscript introduced an easy-to-prepare Schiff base L by condensing vitamin B6 cofactor pyridoxal 5'-phosphate (PLP) with 2-aminothiophenol for the fluorescence turn-on sensing of bovine serum albumin (BSA) and ovalbumin (OVA). The weakly emissive L showed a significant fluorescence enhancement at 485 and 490 nm in the presence of OVA and BSA with an estimated sensitivity limit of 1.7 µM and 0.3 µM, respectively. The formation of protein-ligand complex restricted the free intramolecular rotation of L is expected to show the selective fluorescence enhancement. The molecular docking and molecular dynamics simulations were performed to examine the binding affinity and modes between BSA/OVA and L. The practical utility of L as a fluorescent turn-on sensor was validated by quantifying BSA and OVA in various real biological samples of milk, serum, egg white and urine with good recovery percentages.


Assuntos
Soroalbumina Bovina , Vitamina B 6 , Ligantes , Simulação de Acoplamento Molecular , Ovalbumina , Fosfatos , Fosfato de Piridoxal/química , Fosfato de Piridoxal/metabolismo , Bases de Schiff/química , Soroalbumina Bovina/química , Espectrometria de Fluorescência , Vitamina B 6/química , Vitaminas
9.
Sci Rep ; 12(1): 14870, 2022 Sep 01.
Artigo em Inglês | MEDLINE | ID: mdl-36050498

RESUMO

The control of postprandial hyperglycemia is an important target in the treatment of type 2 diabetes mellitus (T2DM). As a result, targeting α-glucosidase as the most important enzyme in the breakdown of carbohydrates to glucose that leads to an increase in postprandial hyperglycemia is one of the treatment processes of T2DM. In the present work, a new class of benzimidazole-Schiff base hybrids 8a-p has been developed based on the potent reported α-glucosidase inhibitors. These compounds were synthesized by sample recantations, characterized by 1H-NMR, 13C-NMR, FT-IR, and CHNS elemental analysis, and evaluated against α-glucosidase. All new compounds, with the exception of inactive compound 8g, showed excellent inhibitory activities (60.1 ± 3.6-287.1 ± 7.4 µM) in comparison to acarbose as the positive control (750.0 ± 10.5). Kinetic study of the most potent compound 8p showed a competitive type of inhibition (Ki value = 60 µM). In silico induced fit docking and molecular dynamics studies were performed to further investigate the interaction, orientation, and conformation of the title new compounds over the active site of α-glucosidase. In silico druglikeness analysis and ADMET prediction of the most potent compounds demonstrated that these compounds were druglikeness and had satisfactory ADMET profile.


Assuntos
Diabetes Mellitus Tipo 2 , Hiperglicemia , Benzimidazóis/farmacologia , Domínio Catalítico , Diabetes Mellitus Tipo 2/tratamento farmacológico , Inibidores de Glicosídeo Hidrolases/química , Humanos , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Estrutura Molecular , Bases de Schiff/química , Bases de Schiff/farmacologia , Espectroscopia de Infravermelho com Transformada de Fourier , Relação Estrutura-Atividade , alfa-Glucosidases/metabolismo
10.
Nat Commun ; 13(1): 5501, 2022 Sep 20.
Artigo em Inglês | MEDLINE | ID: mdl-36127376

RESUMO

Rhodopsins had long been considered non-fluorescent until a peculiar voltage-sensitive fluorescence was reported for archaerhodopsin-3 (Arch3) derivatives. These proteins named QuasArs have been used for imaging membrane voltage changes in cell cultures and small animals, but they could not be applied in living rodents. To develop the next generation of sensors, it is indispensable to first understand the molecular basis of the fluorescence and its modulation by the membrane voltage. Based on spectroscopic studies of fluorescent Arch3 derivatives, we propose a unique photo-reaction scheme with extended excited-state lifetimes and inefficient photoisomerization. Molecular dynamics simulations of Arch3, of the Arch3 fluorescent derivative Archon1, and of several its mutants have revealed different voltage-dependent changes of the hydrogen-bonding networks including the protonated retinal Schiff-base and adjacent residues. Experimental observations suggest that under negative voltage, these changes modulate retinal Schiff base deprotonation and promote a decrease in the populations of fluorescent species. Finally, we identified molecular constraints that further improve fluorescence quantum yield and voltage sensitivity.


Assuntos
Rodopsinas Microbianas , Bases de Schiff , Animais , Hidrogênio , Ligação de Hidrogênio , Rodopsinas Microbianas/química , Rodopsinas Microbianas/genética , Bases de Schiff/química , Análise Espectral
11.
Colloids Surf B Biointerfaces ; 218: 112727, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35921691

RESUMO

Much research has been done on traditional homogeneous metal catalysts and enzymatic catalysts, but recently a new class of hybrid catalysts called synthetic (artificial) metalloenzymes has been considered by researchers. Metalloenzymes as hybrid catalysts (host-guest systems) have been shown that combine the properties of a homogeneous and also enzymatic catalyst. The hybrid catalyst will have added value such as enantioselectivity or chemo-selectivity. This review focuses on Schiff base complexes that either act as homogeneous artificial enzymes or contribute to the structure of a host in the preparation of hybrid metalloenzymes. Because this approach can virtually be applied to any bio- or synthetic host or guest coordination complex, the details of hybrid catalysts seem important for advance in catalysis.


Assuntos
Metaloproteínas , Bases de Schiff , Catálise , Metaloproteínas/química
12.
Colloids Surf B Biointerfaces ; 218: 112738, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35930984

RESUMO

Hydrogels have been used widely as wound dressings for maintaining a moist environment to rapid wound healing. However, the lack of antibacterial effect limits their further applications. Herein, we developed a polysaccharide-based hydrogel that can achieve photothermal-assisted bacterial inactivation. The hydrogel has inherent antibacterial activity due to introduction of quaternised chitosan (QCS) with a protonated amine group-modified hydrophilic polycationic structure. Under near infrared (NIR) irradiation, the antibacterial effect of the hydrogel was significantly improved because thermal ablation could also combat bacteria. The hydrogel showed self-healing property through reversible Schiff base bonds between QCS and oxidized hyaluronic acid (OHA). The hydrogel is also pH-sensitive to release drugs in acidic wound. The full-thickness skin defect model showed it had a promoting effect on wound healing. Overall, we provide a theoretical basis for a promising wound dressing based on a photothermally improved polysaccharide-based hydrogel with self-healing/pH-responsive/inherently antibacterial capacity.


Assuntos
Quitosana , Hidrogéis , Aminas , Antibacterianos/química , Antibacterianos/farmacologia , Bandagens , Quitosana/química , Quitosana/farmacologia , Ácido Hialurônico/química , Ácido Hialurônico/farmacologia , Hidrogéis/química , Hidrogéis/farmacologia , Concentração de Íons de Hidrogênio , Polissacarídeos/farmacologia , Bases de Schiff/química
13.
Chem Biodivers ; 19(9): e202200425, 2022 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-35959557

RESUMO

An aggregation-induced emission (AIE) active Schiff base L was obtained by reacting pyridoxal and 2-hydroxy-1-naphthaldehyde with p-phenylenediamine in two simple steps. The colorimetric, UV/VIS and fluorescence studies of L revealed that the yellow emissive L (λem =540 nm, λex =450 nm) in pure DMSO turned to a red-emissive L, when the poor solvent fraction (HEPES buffer, 10 mM, pH 7.4) was increased above 50 % in DMSO. The SEM and DLS results indicated the formation of self-aggregates of L that restricted the intramolecular motion and promoted the excited state intramolecular proton transfer (ESIPT) process. The cations sensing ability of the AIEgen L was explored in HEPES buffer (5 % DMSO, 10 mM, pH 7.4), where Cu2+ selectively quenched the fluorescence at 608 nm due to the chelation-enhanced fluorescence quenching (CHEQ) effect with an estimated sensitivity limit of 0.9 µM. Subsequently, the in situ formed AIEgen L-Cu2+ complex was applied for the cascade detection of glutathione (GSH), cysteine (Cys) and homocysteine (Hcy). The decomplexation of Cu2+ from the AIEgen L-Cu2+ by GSH, Cys and Hcy restored the quenched fluorescence emission of AIEgen L at 608 nm. With this Cu2+ displacement approach, the concentration of Cys, Hcy and GSH can be detected down to 2.8 µM, 3.12 µM and 2.0 µM, respectively. The practical utility of AIEgen L and AIEgen L-Cu2+ was examined by monitoring the selective analytes in real environmental and biological samples, and also applied successfully for the cell imaging applications.


Assuntos
Cobre , Cisteína , Cobre/química , Dimetil Sulfóxido , Corantes Fluorescentes/química , Glutationa , HEPES , Homocisteína , Prótons , Piridoxal , Bases de Schiff , Solventes , Espectrometria de Fluorescência
14.
Colloids Surf B Biointerfaces ; 218: 112756, 2022 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-35988312

RESUMO

High efficiency of in-situ cross-linking and acid triggered drug delivery is realized by introducing tobramycin into the hydrogels. Injectable and biodegradable hydrogels are prepared through two steps: First generation of reactive aldehyde groups in the sodium alginate (A-Alg) and then introduction of antibiotic tobramycin as cross-linker. Due to the formation of dynamic Schiff base bonds between the amino groups in tobramycin and aldehyde groups in A-Alg, the gelation of hydrogels can be realized immediately. Thus, tobramycin acts well as the first role cross-linker and the hydrogels containing tobramycin can be injected into the wound during the treatment. In addition, the acid from the decomposition of organic compounds by the bacteria can break the cross-linking points previously formed by tobramycin in the hydrogels. Therefore, tobramycin can be released and act as the second role model drug to kill the bacteria. Because the hydrogels network is broken, the release of tobramycin is more efficient than the traditional drug delivery from hydrogels by diffusion. Based on these unique properties, the present hydrogels containing tobramycin exhibit a good injectable and biodegradable capability. In addition, due to the existence of the reversible acid-labile linkages in the hydrogels, the hydrogels containing tobramycin are also self-healing, which additionally is favorable for the application of wound dressing. More importantly, the antibacterial hydrogels also demonstrate good biocompatibility in vitro and significantly therapeutic effects on an infected mice model in vivo. Based on the above special properties, the hydrogels cross-linked by tobramycin indicate a new approach to prepare hydrogel dressings with low-cost, non-toxicity and good anti-bacterial performance in the treatment of infectious wounds.


Assuntos
Hidrogéis , Tobramicina , Aldeídos , Alginatos/química , Animais , Antibacterianos/química , Antibacterianos/farmacologia , Hidrogéis/química , Camundongos , Bases de Schiff/química , Tobramicina/farmacologia
15.
Langmuir ; 38(33): 10081-10088, 2022 08 23.
Artigo em Inglês | MEDLINE | ID: mdl-35960200

RESUMO

Improving the development of high-value multifunctional wool fabrics was essential to satisfy diverse needs. Considering the various characteristics of chitosan macromolecules, herein, a padding-cross-linking process was adopted and then multifunctional wool fabrics with outstanding printing effects, shrink resistance, and antibacterial properties were fabricated. The test results showed that chitosan macromolecules loaded successfully on the wool fiber surface by Schiff base reaction. Wool fabrics changed from hydrophobic to hydrophilic due to the existence of chitosan macromolecules. The color strength (K/S value) of the reactive dye inkjet-printed wool fabric was greatly increased from 20.48 to 26.6. The area shrinkage of final samples was 2.53%, which was exceedingly lower than that of the original wool (10.96%). Moreover, the chitosan macromolecules with reactive amino groups endowed wool fabrics with certain antibacterial properties against E. coli and S. aureus. Generally, this study provided guidance for manufacturing multifunctional digital inkjet-printed wool products in mass production.


Assuntos
Quitosana , Fibra de Lã , Antibacterianos/química , Antibacterianos/farmacologia , Quitosana/química , Escherichia coli , Bases de Schiff , Staphylococcus aureus
16.
Int J Mol Sci ; 23(16)2022 Aug 18.
Artigo em Inglês | MEDLINE | ID: mdl-36012548

RESUMO

Chitosan-based composite films with good biodegradability, biocompatibility, and sustainability are extensively employed in the field of food packaging. In this study, novel chitosan/tannic acid (CTA) and chitosan/oxidized tannic acid (COTA) composite films with excellent mechanical and antibacterial properties were prepared using a tape casting method. The results showed that, when 20% tannic acid (TA) was added, the tensile strength of the CTA composite film was 80.7 MPa, which was 89.4% higher than that of the pure chitosan (CS) film. TA was oxidized to oxidized tannic acid (OTA) with laccase, and the phenolic hydroxyl groups were oxidized to an o-quinone structure. With the addition of OTA, a Schiff base reaction between the OTA and CS occurred, and a dual network structure consisting of a chemical bond and hydrogen bond was constructed, which further improved the mechanical properties. The tensile strength of 3% COTA composite film was increased by 97.2% compared to that of pure CS film. Furthermore, these CTA films with significant antibacterial effects against Escherichia coli (E. coli) are likely to find uses in food packaging applications.


Assuntos
Quitosana , Antibacterianos/química , Antibacterianos/farmacologia , Quitosana/química , Escherichia coli , Embalagem de Alimentos/métodos , Ligação de Hidrogênio , Bases de Schiff/farmacologia , Taninos/química , Resistência à Tração
17.
Molecules ; 27(16)2022 Aug 10.
Artigo em Inglês | MEDLINE | ID: mdl-36014341

RESUMO

Tannery industries are one of the extensive industrial activities which are the major source of chromium contamination in the environment. Chromium contamination has been an increasing threat to the environment and human health. Therefore, the removal of chromium ions is necessary to save human society. This study is oriented toward the preparation of a new triazole Schiff base derivatives for the remediation of chromium ions. 4,4'-((1E)-1,2-bis ((1H-1,2,4-triazol-3-yl) imino)ethane-1,2-diyl) diphenol was prepared by the interaction between 3-Amino-1H-1,2,4-triazole and 4,4'-Dihydroxybenzil. Then, the produced Schiff base underwent a phosphorylation reaction to produce the adsorbent (TIHP), which confirmed its structure via the different tools FTIR, TGA, 1HNMR, 13CNMR, GC-MS, and Phosphorus-31 nuclear magnetic resonance (31P-NMR). The newly synthesized adsorbent (TIHP) was used to remove chromium oxyanions (Cr(VI)) from an aqueous solution. The batch technique was used to test many controlling factors, including the pH of the working aqueous solution, the amount of adsorbent dose, the initial concentration of Cr(VI), the interaction time, and the temperature. The desorption behaviour of Cr(VI) changes when it is exposed to the suggested foreign ions. The maximum adsorption capacity for Cr(VI) adsorption on the new adsorbent was 307.07 mg/g at room temperature. Freundlich's isotherm model fits the adsorption isotherms perfectly. The kinetic results were well-constrained by the pseudo-second-order equation. The thermodynamic studies establish that the adsorption type was exothermic and naturally spontaneous.


Assuntos
Poluentes Químicos da Água , Purificação da Água , Adsorção , Cromo/química , Humanos , Concentração de Íons de Hidrogênio , Íons , Cinética , Bases de Schiff , Triazóis , Águas Residuárias , Poluentes Químicos da Água/química , Purificação da Água/métodos
18.
Molecules ; 27(16)2022 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-36014397

RESUMO

As one of the main nuclear wastes generated in the process of nuclear fission, radioactive iodine has attracted worldwide attention due to its harm to public safety and environmental pollution. Therefore, it is of crucial importance to develop materials that can rapidly and efficiently capture radioactive iodine. Herein, we report the construction of three electron-rich porous organic polymers (POPs), denoted as POP-E, POP-T and POP-P via Schiff base polycondensations reactions between Td-symmetric adamantane knot and four-branched "linkage" molecules. We demonstrated that all the three POPs showed high iodine adsorption capability, among which the adsorption capacity of POP-T for iodine vapor reached up to 3.94 g·g-1 and the removal rate of iodine in n-hexane solution was up to 99%. The efficient iodine capture mechanism of the POP-T was investigated through systematic comparison of Fourier transform infrared spectroscopy (FT-IR), Raman spectroscopy and X-ray photoelectron spectroscopy (XPS) before and after iodine adsorption. The unique π-π conjugated system between imine bonds linked aromatic rings with iodine result in charge-transfer complexes, which explains the exceptional iodine capture capacity. Additionally, the introduction of heteroatoms into the framework would also enhance the iodine adsorption capability of POPs. Good retention behavior and recycling capacity were also observed for the POPs.


Assuntos
Iodo , Neoplasias da Glândula Tireoide , Elétrons , Humanos , Iodetos , Iodo/química , Radioisótopos do Iodo , Polímeros/química , Porosidade , Bases de Schiff , Espectroscopia de Infravermelho com Transformada de Fourier
19.
Molecules ; 27(16)2022 Aug 15.
Artigo em Inglês | MEDLINE | ID: mdl-36014445

RESUMO

Schiff bases are a class of organic compounds with azomethine moiety, exhibiting a wide range of biological potentials. In this research, six chiral Schiff bases, three 'S' series (H1-H3) and three 'R' series (H4-H6), were synthesized. The reaction was neat, which means without a solvent, and occurred at room temperature with a high product yield. The synthesized compounds were evaluated for analgesic potential in vivo at doses of 12.5 and 25 mg/kg using acetic-acid-induced writhing assay, formalin test, tail immersion and hot plate models, followed by investigating the possible involvement of opioid receptors. The compounds H2 and H3 significantly (*** p < 0.001) reduced the writhing frequency, and H3 and H5 significantly (*** p < 0.001) reduced pain in both phases of the formalin test. The compounds H2 and H5 significantly (*** p < 0.001) increased latency at 90 min in tail immersion, while H2 significantly (*** p < 0.001) increased latency at 90 min in the hot plate test. The 'S' series Schiff bases, H1-H3, were found more potent than the 'R' series compounds, H4-H6. The possible involvement of opioid receptors was also surveyed utilizing naloxone in tail immersion and hot plate models, investigating the involvement of opioid receptors. The synthesized compounds could be used as alternative analgesic agents subjected to further evaluation in other animal models to confirm the observed biological potential.


Assuntos
Extratos Vegetais , Bases de Schiff , Analgésicos/uso terapêutico , Animais , Dor/tratamento farmacológico , Extratos Vegetais/farmacologia , Receptores Opioides , Bases de Schiff/farmacologia
20.
Molecules ; 27(16)2022 Aug 19.
Artigo em Inglês | MEDLINE | ID: mdl-36014538

RESUMO

Oxyfunctionalization of toluene to value-added benzaldehyde, benzyl alcohol and benzoic acid is of great significance. In this work, Co-Schiff bases were immobilized on commercial silica gel by covalent anchoring, and resulting catalysts were used to catalyze the oxidation of toluene in the presence of the cocatalyst N-hydroxyphthalimide (NHPI). The catalysts exhibited excellent textural and structural properties, reliable bonding and a predomination of the cobaltous ions. The catalyst synthesized by diethylamino salicylaldehyde (EASA) possessed a grafting density of 0.14 mmol/g and exhibited a toluene conversion of 37.5%, with predominant selectivities to benzaldehyde, benzyl alcohol and benzoic acid under solvent-free conditions. It is concluded that the effect of ligands on their catalytic performance might be related to their electron-donating or -withdrawing properties.


Assuntos
Bases de Schiff , Tolueno , Benzaldeídos , Ácido Benzoico/química , Álcool Benzílico/química , Tolueno/química
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