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1.
Int J Mol Sci ; 22(6)2021 Mar 16.
Artigo em Inglês | MEDLINE | ID: mdl-33809708

RESUMO

A typical feature of proteins from the rhodopsin family is the sensitivity of their absorption band maximum to protein amino acid composition. For this reason, studies of these proteins often require methodologies that determine spectral shift caused by amino acid substitutions. Generally, quantum mechanics/molecular mechanics models allow for the calculation of a substitution-induced spectral shift with high accuracy, but their application is not always easy and requires special knowledge. In the present study, we propose simple models that allow us to estimate the direct effect of a charged or polar residue substitution without extensive calculations using only rhodopsin three-dimensional structure and plots or tables that are provided in this article. The models are based on absorption maximum values calculated at the SORCI+Q level of theory for cis- and trans-forms of retinal protonated Schiff base in an external electrostatic field of charges and dipoles. Each value corresponds to a certain position of a charged or polar residue relative to the retinal chromophore. The proposed approach was evaluated against an example set consisting of twelve bovine rhodopsin and sodium pumping rhodopsin mutants. The limits of the applicability of the models are also discussed. The results of our study can be useful for the interpretation of experimental data and for the rational design of rhodopsins with required spectral properties.


Assuntos
Aminoácidos/química , Proteínas de Bactérias/química , Modelos Moleculares , Rodopsina/química , Análise Espectral , Eletricidade Estática , Substituição de Aminoácidos , Animais , Bovinos , Mutação/genética , Prótons , Rodopsina/genética , Bases de Schiff/química
2.
Molecules ; 26(5)2021 Feb 25.
Artigo em Inglês | MEDLINE | ID: mdl-33669147

RESUMO

An aniline-functionalized naphthalene dialdehyde Schiff base fluorescent probe L with aggregation-induced enhanced emission (AIEE) characteristics was synthesized via a simple one-step condensation reaction and exhibited excellent sensitivity and selectivity towards copper(II) ions in aqueous media with a fluorescence " turn-off " phenomenon. The detection limit of the probe is 1.64 × 10-8 mol·L-1. Furthermore, according to the results of the UV-vis/fluorescence titrations, Job's plot method and 1H-NMR titrations, a 1:2 stoichiometry was identified. The binding constant between L and Cu2+ was calculated to be Ka = 1.222 × 103. In addition, the AIEE fluorescent probe L could be applied to detection in real water samples with satisfactory recoveries in the range 99.10-102.90% in lake water and 98.49-102.37% in tap water.


Assuntos
Cobre/análise , Corantes Fluorescentes/química , Naftalenos/química , Poluentes Químicos da Água/análise , Cristalografia por Raios X , Corantes Fluorescentes/síntese química , Íons/análise , Modelos Moleculares , Estrutura Molecular , Naftalenos/síntese química , Bases de Schiff/síntese química , Bases de Schiff/química
3.
Molecules ; 26(4)2021 Feb 11.
Artigo em Inglês | MEDLINE | ID: mdl-33670156

RESUMO

Recently, metal-coordinated orthogonal self-assembly has been used as a feasible and efficient method in the construction of polymeric materials, which can also provide supramolecular self-assembly complexes with different topologies. Herein, a cryptand with a rigid pyridyl group on the third arm derived from BMP32C10 was synthesized. Through coordination-driven self-assembly with a bidentate organoplatinum(II) acceptor or tetradentate Pd(BF4)2•4CH3CN, a di-cryptand complex and tetra-cryptand complex were prepared, respectively. Subsequently, through the addition of a di-paraquat guest, linear and cross-linked supramolecular polymers were constructed through orthogonal self-assembly, respectively. By comparing their proton nuclear magnetic resonance (1H NMR) and diffusion-ordered spectroscopy (DOSY) spectra, it was found that the degrees of polymerization were dependent not only on the concentrations of the monomers but also on the topologies of the supramolecular polymers.


Assuntos
Complexos de Coordenação/química , Éteres Cíclicos/química , Metais/química , Paraquat/química , Bases de Schiff/química , Substâncias Macromoleculares/química , Estrutura Molecular , Polímeros/química
4.
Molecules ; 26(5)2021 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-33668169

RESUMO

A series of fifteen silver (I) quinoline complexes Q1-Q15 have been synthesized and studied for their biological activities. Q1-Q15 were synthesized from the reactions of quinolinyl Schiff base derivatives L1-L5 (obtained by condensing 2-quinolinecarboxaldehyde with various aniline derivatives) with AgNO3, AgClO4 and AgCF3SO3. Q1-Q15 were characterized by various spectroscopic techniques and the structures of [Ag(L1)2]NO3Q1, [Ag(L1)2]ClO4Q6, [Ag(L2)2]ClO4Q7, [Ag(L2)2]CF3SO3Q12 and [Ag(L4)2]CF3SO3Q14 were unequivocally determined by single crystal X-ray diffraction analysis. In vitro antimicrobial tests against Gram-positive and Gram-negative bacteria revealed the influence of structure and anion on the complexes' moderate to excellent antibacterial activity. In vitro antioxidant activities of the complexes showed their good radical scavenging activity in ferric reducing antioxidant power (FRAP). Complexes with the fluorine substituent or the thiophene or benzothiazole moieties are more potent with IC50 between 0.95 and 2.22 mg/mL than the standard used, ascorbic acid (2.68 mg/mL). The compounds showed a strong binding affinity with calf thymus-DNA via an intercalation mode and protein through a static quenching mechanism. Cytotoxicity activity was examined against three carcinoma cell lines (HELA, MDA-MB231, and SHSY5Y). [Ag(L2)2]ClO4Q7 with a benzothiazole moiety and [Ag(L4)2]ClO4Q9 with a methyl substituent had excellent cytotoxicity against HELA cells.


Assuntos
Antibacterianos/farmacologia , Antineoplásicos/farmacologia , Antioxidantes/farmacologia , Complexos de Coordenação/farmacologia , DNA/química , Antibacterianos/síntese química , Antibacterianos/química , Antineoplásicos/síntese química , Antineoplásicos/química , Antioxidantes/síntese química , Antioxidantes/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Complexos de Coordenação/síntese química , Complexos de Coordenação/química , Ensaios de Seleção de Medicamentos Antitumorais , Compostos Férricos/antagonistas & inibidores , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Oxirredução , Quinolinas/química , Quinolinas/farmacologia , Bases de Schiff/química , Bases de Schiff/farmacologia , Prata/química , Prata/farmacologia
5.
Carbohydr Polym ; 260: 117815, 2021 May 15.
Artigo em Inglês | MEDLINE | ID: mdl-33712159

RESUMO

Chitosan is a versatile polysaccharide in different domains due to facile modification and good biodegradability. In this paper, taking advantage of such functional properties, we have developed a stabilizer agent [OCMCS-SB] produced from chitosan, and palladium was successfully immobilized on this designed stabilizer [OCMCS-SB-Pd(II)]. The obtained complex was illuminated by 13C CP-MAS NMR, FT-IR, TGA, XRD, XPS, SEM, TEM and ICP-OES analyses. Due to the interactions of primary hydroxyl groups on chitosan, Schiff base and carboxy groups, the Pd complex showed excellent reactivity (up to 99 %) and stability towards Suzuki reactions in eco-friendly medium. Subsequently, the reusability experiments for OCMCS-SB-Pd(II) formed from chitosan were examined in five consecutive cycles, which showed no appreciable decrease in activity. Furthermore, a reasonably trifunctional complex structure was proposed. The present bio-based system offers a promising approach in utilizing such biopolymers in organic transformations.


Assuntos
Quitosana/química , Paládio/química , Catálise , Bases de Schiff/química , Espectroscopia de Infravermelho com Transformada de Fourier
6.
Molecules ; 26(5)2021 Feb 28.
Artigo em Inglês | MEDLINE | ID: mdl-33670879

RESUMO

Four flavanone Schiff bases (E)-1-(2-phenylchroman-4-ylidene)thiosemicarbazide (FTSC) (1), N',2-bis((E)-2-phenylchroman-4-ylidene)hydrazine-1-carbothiohydrazide (FTCH) (2), (E)-N'-(2-phenylchroman-4-ylidene)benzohydrazide (FHSB) (3) and (E)-N'-(2-phenylchroman-4-ylidene)isonicotinohydrazide (FIN) (4) were synthesized and evaluated for their electronic and physicochemical properties using experimental and theoretical methods. One of them, (2), consists of two flavanone moieties and one substituent, the rest of the compounds (1, 3, 4) comprises of a flavanone-substituent system in relation to 1:1. To uncover the structural and electronic properties of flavanone Schiff bases, computational simulations and absorption spectroscopy were applied. Additionally, binding efficiencies of the studied compounds to serum albumins were evaluated using fluorescence spectroscopy. Spectral profiles of flavanone Schiff bases showed differences related to the presence of substituent groups in system B of the Schiff base molecules. Based on the theoretically predicted chemical descriptors, FTSC is the most chemically reactive among the studied compounds. Binding regions within human and bovine serum albumins of the ligands studied are in the vicinity of the Trp residue and a static mechanism dominates in fluorescence quenching.


Assuntos
Flavanonas/química , Bases de Schiff/química , Albumina Sérica/química , Sequência de Aminoácidos , Animais , Bovinos , Teoria da Densidade Funcional , Humanos , Ligantes , Simulação de Acoplamento Molecular , Ligação Proteica , Espectrometria de Fluorescência , Espectrofotometria , Relação Estrutura-Atividade
7.
ACS Appl Mater Interfaces ; 13(7): 9006-9014, 2021 Feb 24.
Artigo em Inglês | MEDLINE | ID: mdl-33576614

RESUMO

The development and application of natural antibacterial materials have always been the focus of biomedical research. Borneol as a natural antibacterial compound has received extensive attention. However, the hydrophobicity caused by its unique structure limits its application range to a certain extent. In this study, we combine zwitterionic 2-methacryloyloxyethyl phosphorylcholine (MPC) with a complex bicyclic monoterpene structure borneol compound and prepare an excellent antifouling and antibacterial surface via the Schiff-base bond. The prepared coating has excellent hydrophilicity verified by the contact angle (CA), and its polymer layer is confirmed by X-ray photoelectron spectroscopy (XPS). The zwitterion MPC and borneol moieties in the copolymer play a coordinating role, relying on super hydration and the special stereochemical structure to prevent protein adsorption and inhibit bacterial adhesion, respectively, which are demonstrated by bovine serum albumin (BSA) adsorption and antibacterial activity test. Moreover, the water-soluble borneol derivative as the antibacterial surfaces we designed here was biocompatible toward MRC-5 (lung fibroblasts), as showed by in vitro cytotoxicity assays. Such results indicate the potential application of the as-prepared hydrophilic surfaces in the biomedical materials.


Assuntos
Antibacterianos/farmacologia , Incrustação Biológica/prevenção & controle , Canfanos/farmacologia , Materiais Revestidos Biocompatíveis/farmacologia , Metacrilatos/farmacologia , Fosforilcolina/análogos & derivados , Polímeros/farmacologia , Adsorção , Antibacterianos/síntese química , Antibacterianos/química , Canfanos/química , Sobrevivência Celular/efeitos dos fármacos , Materiais Revestidos Biocompatíveis/síntese química , Materiais Revestidos Biocompatíveis/química , Escherichia coli/efeitos dos fármacos , Humanos , Metacrilatos/química , Testes de Sensibilidade Microbiana , Estrutura Molecular , Tamanho da Partícula , Fosforilcolina/química , Fosforilcolina/farmacologia , Polímeros/síntese química , Polímeros/química , Bases de Schiff/síntese química , Bases de Schiff/química , Bases de Schiff/farmacologia , Soroalbumina Bovina/química , Staphylococcus aureus/efeitos dos fármacos , Propriedades de Superfície
8.
Food Chem ; 347: 128985, 2021 Jun 15.
Artigo em Inglês | MEDLINE | ID: mdl-33476920

RESUMO

As the most important tenderness related protein in mammal, there are few studies on how the nanoscale morphology of collagen I in tissues is related to traditional meat processing. The ultrastructure and mechanical characteristics of collagen fibers in tendon with different treatments have been explored in this study. Collagen fibers in homogenate group and acetic acid group were treated with ultrasound and thermal treatment. The nanoscale morphology of collagen fiber in homogenate group became granular at 60 °C and gelatin was formed at 70 °C. The collagen fibers extracted from acetic acid are unstable and easier to break under the same processing parameters, when compared with homogenated collagen fibers in both ultrasound and thermal treatment. The results suggested that acetic acid can disassemble the salt bond and Schiff-base in collagen, and the collagen fibers became loose but the triple helix structure remained integrity.


Assuntos
Colágeno/ultraestrutura , Microscopia de Força Atômica , Tendões/metabolismo , Ácido Acético/química , Animais , Bovinos , Colágeno/química , Bases de Schiff/química , Sonicação , Temperatura
9.
Food Chem ; 348: 129098, 2021 Jun 30.
Artigo em Inglês | MEDLINE | ID: mdl-33515942

RESUMO

We report the modular design and synthesis of an amine dangled Schiff base quinoline-morpholine conjugate (QMC) for highly selective detection of Pb2+ ions via fluorimetry. The sensing strategy of QMC towards Pb2+ ion exhibits a large blue shift with fluorescent enhancement via the intramolecular charge transfer (ICT) process. At the same time, QMC coordination with Pb2+, the CN single bond rotation between quinoline and morpholine rings and the CN isomerization process were blocked. Best of our knowledge, this is the first blue shifted turn-on fluorescent chemosensor for Pb2+ ion via the ICT process. Furthermore, QMC selectively detects Pb2+ ion without any interference with alkali, alkaline earth, and transition metal ions, and limit of detection (LOD) downs to 13 µM, which is a permissible level of Pb2+ ion in drinking water reported by WHO. The 1:2 binding stoichiometry between QMC and Pb2+ was confirmed by fluorimetric, 1H NMR titration, mass spectrometry, and theoretical studies. Finally, QMC was potentially applied for the sensing of Pb2+ ions in milk, red wine, live cells and an INHIBIT molecular logic function was constructed by using Pb2+ and EDTA as chemical inputs.


Assuntos
Corantes Fluorescentes/química , Lógica , Leite/química , Imagem Molecular/métodos , Quinolinas/química , Animais , Chumbo/análise , Chumbo/química , Limite de Detecção , Bases de Schiff/química , Espectrometria de Fluorescência
10.
Int J Biol Macromol ; 170: 222-231, 2021 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-33359811

RESUMO

The periodate modified gum arabic was used as a natural-based, non-toxic cross-linker to synthesize hybrid bovine serum albumin-gum arabic aldehyde (BSA-GAA) nanogels by Schiff base reaction through the inverse miniemulsion method for the first time. The synthesis process was performed in the absence of toxic organic solvents using fractionated coconut oil as the continuous phase. The particle size of the nanogels was managed by tweaking the concentration of the surfactants (Span 80/Tween 80) and the total volume of the aqueous phase. Based on the bicinchoninic acid method, the cross-linking efficiency of BSA and GAA was estimated at 98%. 5-fluorouracil (5-FU) was selected as the sample drug. The 5-FU-loaded hybrid nanogels showed a spherical morphology with an average diameter of 231.33 ±12.74 nm and a zeta potential of -31.6 mV. The encapsulation and loading efficiency of the nanogels were calculated at 42 ± 4.52% and 2.37 ± 0.59%, respectively. The properties of the hybrid nanogels were analyzed by dynamic light scattering (DLS), Fourier transform infrared microscopy (FTIR) analysis, field emission scanning electron microscopy (FE-SEM), and thermogravimetric analysis (TGA). The pH sensitivity of the hybrid nanogels was confirmed by the in vitro release profiles of 5-FU in different buffers. Hemolysis assay revealed the in vitro hemocompatibility of the hybrid nanogels which inhibited the growth of MCF-7 cells with an IC50 value of 16.21 µM. The present study suggested that these biobased hybrid nanogels could have a great potential in drug delivery and other biomedical applications.


Assuntos
Sistemas de Liberação de Medicamentos/métodos , Nanogéis/química , Bases de Schiff/química , Aldeídos/química , Antineoplásicos , Liberação Controlada de Fármacos , Gelatina/química , Goma Arábica/química , Humanos , Células MCF-7 , Nanopartículas/química , Tamanho da Partícula , Polietilenoglicóis/química , Polietilenoimina/química , Soroalbumina Bovina/química , Tensoativos/química
11.
Gene ; 763: 144997, 2020 Dec 30.
Artigo em Inglês | MEDLINE | ID: mdl-32783992

RESUMO

The CRISPR-Cas system currently stands as one of the best multifaceted tools for site-specific genome engineering in mammals. An important aspect of research in this field focusses on improving the specificity and efficacy of precise genome editing in multiple model systems. The cornerstone of this mini-review is one of the extensively investigated small molecule inhibitor, SCR7, which abrogates NHEJ, a Ligase IV-dependent DSB repair pathway, thus guiding integration of the foreign DNA fragment via the more precise homology directed repair during genome editing. One of our recent studies sheds light on properties of different forms of SCR7. Here, we give a succinct account on the use of SCR7 and its different forms in CRISPR-Cas system, highlighting their chemical properties and biological relevance as potent efficiency-enhancing CRISPR tools.


Assuntos
Sistemas CRISPR-Cas , Inibidores Enzimáticos/farmacologia , Edição de Genes/métodos , Pirimidinas/farmacologia , Reparo de DNA por Recombinação/efeitos dos fármacos , Bases de Schiff/farmacologia , Animais , DNA Ligase Dependente de ATP/antagonistas & inibidores , Inibidores Enzimáticos/química , Humanos , Pirimidinas/química , Bases de Schiff/química
12.
PLoS One ; 15(6): e0229891, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32497076

RESUMO

A facile method has been developed for the synthesis of Schiff bases derived from substituted and unsubstituted 3-amino- and 4-amino-1,2,4-triazoles. Condensation of the aminotrizoles with a variety of aromatic aldehydes afforded desired Schiff bases in excellent yields in 3-5 minutes of exposure to ultra-sound. The synthesized compounds were characterized by means of IR, 1HNMR and Mass spectrometry. The synthesized compounds were also screened for their antibacterial potential against Gram-negative (Escherichia coli, Shigella sonnei, Pseudomonas aeruginosa and Salmonella typhi) and two Gram-positive (Staphylococcus aureus and Bacillus subtilis) strains.


Assuntos
Amitrol (Herbicida)/síntese química , Amitrol (Herbicida)/farmacologia , Antibacterianos/síntese química , Antibacterianos/farmacologia , Triazóis/síntese química , Triazóis/farmacologia , Ondas Ultrassônicas , Amitrol (Herbicida)/química , Antibacterianos/química , Bactérias/efeitos dos fármacos , Técnicas de Química Sintética , Testes de Sensibilidade Microbiana , Bases de Schiff/química , Triazóis/química
13.
Nature ; 583(7815): 314-318, 2020 07.
Artigo em Inglês | MEDLINE | ID: mdl-32499654

RESUMO

Light-driven sodium pumps actively transport small cations across cellular membranes1. These pumps are used by microorganisms to convert light into membrane potential and have become useful optogenetic tools with applications in neuroscience. Although the resting state structures of the prototypical sodium pump Krokinobacter eikastus rhodopsin 2 (KR2) have been solved2,3, it is unclear how structural alterations over time allow sodium to be translocated against a concentration gradient. Here, using the Swiss X-ray Free Electron Laser4, we have collected serial crystallographic data at ten pump-probe delays from femtoseconds to milliseconds. High-resolution structural snapshots throughout the KR2 photocycle show how retinal isomerization is completed on the femtosecond timescale and changes the local structure of the binding pocket in the early nanoseconds. Subsequent rearrangements and deprotonation of the retinal Schiff base open an electrostatic gate in microseconds. Structural and spectroscopic data, in combination with quantum chemical calculations, indicate that a sodium ion binds transiently close to the retinal within one millisecond. In the last structural intermediate, at 20 milliseconds after activation, we identified a potential second sodium-binding site close to the extracellular exit. These results provide direct molecular insight into the dynamics of active cation transport across biological membranes.


Assuntos
Flavobacteriaceae/química , Rodopsinas Microbianas/química , Rodopsinas Microbianas/efeitos da radiação , ATPase Trocadora de Sódio-Potássio/química , ATPase Trocadora de Sódio-Potássio/efeitos da radiação , Sítios de Ligação , Cristalografia , Elétrons , Transporte de Íons , Isomerismo , Lasers , Prótons , Teoria Quântica , Retinaldeído/química , Retinaldeído/metabolismo , Bases de Schiff/química , Sódio/metabolismo , Análise Espectral , Eletricidade Estática , Fatores de Tempo
14.
J Phys Chem Lett ; 11(11): 4245-4252, 2020 Jun 04.
Artigo em Inglês | MEDLINE | ID: mdl-32374610

RESUMO

The photocycle of a reversible photoisomerizing rhodopsin mimic (M2) is investigated. This system, based on the cellular retinoic acid binding protein, is structurally different from natural rhodopsin systems, but exhibits a similar isomerization upon light irradiation. More specifically, M2 displays a 15-cis to all-trans conversion of retinal protonated Schiff base (rPSB) and all-trans to 15-cis isomerization of unprotonated Schiff base (rUSB). Here we use hybrid quantum mechanics/molecular mechanics (QM/MM) tools coupled with transient absorption and cryokinetic UV-vis spectroscopies to investigate these isomerization processes. The results suggest that primary rPSB photoisomerization of M2 occurs around the C13═C14 double bond within 2 ps following an aborted-bicycle pedal (ABP) isomerization mechanism similar to natural microbial rhodopsins. The rUSB isomerization is much slower and occurs within 48 ps around the C15═N double bond. Our findings reveal the possibility to engineer naturally occurring mechanistic features into artificial rhodopsins and also constitute a step toward understanding the photoisomerization of UV pigments. We conclude by reinforcing the idea that the presence of the retinal chromophore inside a tight protein cavity is not mandatory to exhibit ABP mechanism.


Assuntos
Rodopsina/química , Rodopsina/efeitos da radiação , Isomerismo , Luz , Teoria Quântica , Receptores do Ácido Retinoico , Bases de Schiff/química , Análise Espectral/métodos
15.
Food Chem ; 327: 127080, 2020 Oct 15.
Artigo em Inglês | MEDLINE | ID: mdl-32454274

RESUMO

A hydrazone based Schiff base (SB) has been synthesized and investigated for the detection, quantification and degradation of selective organophosphates (i.e diethyl chlorophosphate, diethyl cyanophosphonate, tris (2-chloroethyl) phosphate and dichlorvos). The organophosphates (OPs) form a covalent bond with -OH groups of SB and form SB-OP which quenches emission signal at 533 nm. Therefore, it can be used for the spectrofluorimetric detection and quantification of OPs upto the detection limits of 10.2, 158.2, 10.3 and 122.7 nM, respectively. Besides, the SB-OP duo undergoes degradation to non-toxic species in the presence of Zn2+ ions. The mechanism of interaction between SB-OP-Zn2+ trio is investigated by spectrofluorometric, spectroscopic, chromatographic and spectrometric experiments. The optimized recognition and degradation protocols were found accurate and precise when applied to fruits, vegetable and soil samples. Overall, the developed protocols prove SB as highly sensitive, selective and recyclable 'pick and degrade' probe for the recognition and degradation of OPs.


Assuntos
Retardadores de Chama/análise , Frutas/química , Organofosfatos/química , Verduras/química , Zinco/química , Cátions Bivalentes , Fosfatos , Bases de Schiff/química
16.
Int J Nanomedicine ; 15: 2583-2603, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32368042

RESUMO

Introduction: Over the past several years, nano-based therapeutics were an effective cancer drug candidate in order to overcome the persistence of deadliest diseases and prevalence of multiple drug resistance (MDR). Methods: The main objective of our program was to design organosilane-modified Fe3O4/SiO2/APTS(~NH2) core magnetic nanocomposites with functionalized copper-Schiff base complex through the use of (3-aminopropyl)triethoxysilane linker as chemotherapeutics to cancer cells. The nanoparticles were characterized by Fourier transform infrared spectroscopy (FT-IR), X-ray powder diffraction (XRD), field emission scanning electron microscopy (FE-SEM), TEM, and vibrating sample magnetometer (VSM) techniques. All analyses corroborated the successful synthesis of the nanoparticles. In the second step, all compounds of magnetic nanoparticles were validated as antitumor drugs through the conventional MTT assay against K562 (myelogenous leukemia cancer) and apoptosis study by Annexin V/PI and AO/EB. The molecular dynamic simulations of nanoparticles were further carried out; afterwards, the optimization was performed using MM+, semi-empirical (AM1) and Ab Initio (STO-3G), ForciteGemo Opt, Forcite Dynamics, Forcite Energy and CASTEP in Materials studio 2017. Results: The results showed that the anti-cancer activity was barely reduced after modifying the surface of the Fe3O4/SiO2/APTS nanoparticles with 2-hydroxy-3-methoxybenzaldehyde as Schiff base and then Cu(II) complex. The apoptosis study by Annexin V/PI and AO/EB stained cell nuclei was performed that apoptosis percentage of the nanoparticles increased upon increasing the thickness of Fe3O4 shell on the magnetite core. The docking studies of the synthesized compounds were conducted towards the DNA and Topoisomerase II via AutoDock 1.5.6 (The Scripps Research Institute, La Jolla, CA, USA). Conclusion: Results of biology activities and computational modeling demonstrate that nanoparticles were targeted drug delivery system in cancer treatment.


Assuntos
Cobre/química , Compostos Férricos/síntese química , Simulação de Acoplamento Molecular , Simulação de Dinâmica Molecular , Propilaminas/síntese química , Bases de Schiff/síntese química , Silanos/síntese química , Dióxido de Silício/síntese química , Apoptose , Núcleo Celular/metabolismo , DNA/química , DNA Topoisomerases Tipo II/química , Compostos Férricos/química , Humanos , Células K562 , Magnetismo , Nanopartículas de Magnetita/química , Nanopartículas de Magnetita/ultraestrutura , Propilaminas/química , Bases de Schiff/química , Silanos/química , Dióxido de Silício/química , Espectroscopia de Infravermelho com Transformada de Fourier , Difração de Raios X
17.
J Chromatogr A ; 1621: 461066, 2020 Jun 21.
Artigo em Inglês | MEDLINE | ID: mdl-32299623

RESUMO

The ion-exchange and complex forming equilibria were quantitatively described and demonstrated in order to understand major factors in the control of selectivity in the analytical separation of carboxylic acids and inorganic anions in cryptand based ion chromatography. A complex retention model has been developed for the separation on a non-conventional IC column. Changes in retention are treated both theoretically and experimentally. Retention mechanism is employed on a macrocycle-based (cryptand n-decyl-[2.2.2]) ion-exchange chromatographic phase to improve the selectivity for a mixture of model analytes. We introduced an alternative internal gradient method by mixed eluent (i.e. eluents formed by combination of two alkali hydroxide with different molar ratio). The effect of binary mixed eluent (Li/Na, Li/K) on the retention behavior and peak shape of carboxylic acids are also discussed in view of the proposed theory. It was shown that the effects of binary aqueous mobile phases, held isocratically behave very similar to the step gradient mode. The "internal gradient" separation system has advantages over traditional step gradient mode. Twenty-six anions of widely varying chemical character (mono-, di-, tri-valent inorganic anions, mono-, di-, tri-valent aliphatic carboxylic acids, aromatic- and haloacetic carboxylic acids) were investigated on the cryptand-based (D222) stationary phase using different methods by LiOH, NaOH and KOH eluent. The predicted vs measured retention data are in rather good agreement. High degree of linearity was obtained for inorganic anions, multivalent carboxylic acids, and for aromatic and haloacetic acids R2 = 0.992, 0.969, and 0.980, respectively.


Assuntos
Ácidos Carboxílicos/análise , Cromatografia por Troca Iônica/métodos , Éteres Cíclicos/química , Bases de Schiff/química , Ácidos/química , Ânions/química , Ácidos Carboxílicos/isolamento & purificação , Troca Iônica
18.
PLoS One ; 15(4): e0231147, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32287324

RESUMO

This paper reports the synthesis, characterization, anticancer screening and quantum chemical calculation of a tetradentate Schiff base 2,2'-((1E,1'E)-((2,2-dimethylpropane-1,3-diyl)bis- (azanylylidene))bis(methanylylidene))bis(4-fluorophenol) (L2F) and its Pd (II) complex (PdL2F). The compounds were characterized via UV-Visible, NMR, IR spectroscopy and single crystal x-ray diffraction. Density Functional Theory (DFT) and time-dependent DFT calculations in gas and solvent phases were carried out using B3LYP, B3P86, CAM-B3LYP and PBE0 hybrid functionals combined with LanL2DZ basis set. Complexation of L2F to form PdL2F was observed to cause a bathochromic shift of the maximum absorption bands of n-π* from 327 to 410 nm; an upfield shift for δ (HC = N) from 8.30 to 7.96 ppm and a decreased wavenumber for ν(C = N) from 1637 to 1616 cm-1. Overall, the UV-Vis, NMR and IR spectral data are relatively well reproduced through DFT and TD-DFT methods. L2F and PdL2F showed IC50 of 90.00 and 4.10 µg/mL, respectively, against human colorectal carcinoma (HCT116) cell lines, signifying increased anticancer activity upon complexation with Pd (II).


Assuntos
Complexos de Coordenação/farmacologia , Paládio/farmacologia , Bases de Schiff/farmacologia , Técnicas de Química Sintética/métodos , Complexos de Coordenação/química , Cristalografia por Raios X , Ensaios de Seleção de Medicamentos Antitumorais , Células HCT116 , Humanos , Concentração Inibidora 50 , Ligantes , Espectroscopia de Ressonância Magnética , Modelos Moleculares , Paládio/química , Bases de Schiff/química , Espectrofotometria Ultravioleta , Espectroscopia de Infravermelho com Transformada de Fourier
19.
Chemistry ; 26(31): 7074-7082, 2020 Jun 02.
Artigo em Inglês | MEDLINE | ID: mdl-32187746

RESUMO

The results of extended comparative investigation of nickel(II) Schiff base complexes (containing various auxiliary chiral moieties) commonly used as a methodological platform for the asymmetric synthesis of tailor-made α-amino acids are provided. The following issues are addressed: 1) redox activity (determining the possibility for electrochemically induced reactions); 2) quantitative estimation of the reactivity of deprotonated complexes towards electrophiles; and 3) quantum-chemical estimation of noncovalent interactions in the metal coordination environment (which shed light on the origin of the stereochemical outcome observed for different stereoinductors). Possible mechanisms that determine the relationship between the stereochemical configuration of a molecule and its electronic structure are discussed. The DFT-calculated HOMO-LUMO energies and localization, as well as relative energies for the (S)- and (R)-alanine derivatives, that determine the stereoinduction efficiency in thermodynamically controlled reactions in nickel(II) coordination are provided. The computational data are supported by experimental results on the monobenzylation of glycine derivatives.


Assuntos
Aminoácidos/química , Complexos de Coordenação/química , Bases de Schiff/química , Alanina/química , Glicina/química , Níquel/química , Estereoisomerismo , Termodinâmica
20.
Biochim Biophys Acta Bioenerg ; 1861(7): 148190, 2020 07 01.
Artigo em Inglês | MEDLINE | ID: mdl-32194062

RESUMO

Krokinobacter rhodopsin 2 (KR2) was discovered as the first light-driven sodium pumping rhodopsin (NaR) in 2013, which contains unique amino acid residues on C-helix (N112, D116, and Q123), referred to as an NDQ motif. Based on the recent X-ray crystal structures of KR2, the sodium transport pathway has been investigated by various methods. However, due to complicated structural information around the protonated Schiff base (PRSB) region in the dark state and lack of structural information in the intermediates with sodium bound in KR2, detailed sodium pump mechanism is still unclear. Here we applied comprehensive low-temperature light-induced difference FTIR spectroscopy on isotopically labeled KR2 WT and site-directed mutant proteins (N112A, D116E, R109A, and R109K). We assigned the N-D stretching vibration of the PRSB at 2095 cm-1 and elucidate the hydrogen bonding interaction with D116 (a counter ion for the PRSB). We also assigned strongly hydrogen-bonded water (2333 cm-1) near R109 and D251, and found that presence of a positive charge at the position of R109 is prerequisite for the pumping function of KR2.


Assuntos
Luz , Retinaldeído/química , Rodopsina/química , Bases de Schiff/química , ATPase Trocadora de Sódio-Potássio/metabolismo , Cristalografia por Raios X , Flavobacteriaceae/metabolismo , Ligação de Hidrogênio , Isomerismo , Modelos Moleculares , Mutagênese Sítio-Dirigida , Proteínas Mutantes/química , Proteínas Mutantes/metabolismo , Isótopos de Nitrogênio , Espectroscopia de Infravermelho com Transformada de Fourier , Vibração , Água/química
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