Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 20.886
Filtrar
Mais filtros

Tipo de documento
Intervalo de ano de publicação
1.
Nature ; 575(7784): 639-642, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31776492

RESUMO

Electrochemical carbon dioxide (CO2) reduction can in principle convert carbon emissions to fuels and value-added chemicals, such as hydrocarbons and alcohols, using renewable energy, but the efficiency of the process is limited by its sluggish kinetics1,2. Molecular catalysts have well defined active sites and accurately tailorable structures that allow mechanism-based performance optimization, and transition-metal complexes have been extensively explored in this regard. However, these catalysts generally lack the ability to promote CO2 reduction beyond the two-electron process to generate more valuable products1,3. Here we show that when immobilized on carbon nanotubes, cobalt phthalocyanine-used previously to reduce CO2 to primarily CO-catalyses the six-electron reduction of CO2 to methanol with appreciable activity and selectivity. We find that the conversion, which proceeds via a distinct domino process with CO as an intermediate, generates methanol with a Faradaic efficiency higher than 40 per cent and a partial current density greater than 10 milliamperes per square centimetre at -0.94 volts with respect to the reversible hydrogen electrode in a near-neutral electrolyte. The catalytic activity decreases over time owing to the detrimental reduction of the phthalocyanine ligand, which can be suppressed by appending electron-donating amino substituents to the phthalocyanine ring. The improved molecule-based electrocatalyst converts CO2 to methanol with considerable activity and selectivity and with stable performance over at least 12 hours.


Assuntos
Dióxido de Carbono , Eletroquímica , Dióxido de Carbono/química , Catálise , Indóis/química , Metanol/síntese química , Nanotubos de Carbono/química , Compostos Organometálicos/química
2.
Nature ; 575(7782): 336-340, 2019 11.
Artigo em Inglês | MEDLINE | ID: mdl-31723273

RESUMO

Organoboron reagents are important synthetic intermediates that have a key role in the construction of natural products, pharmaceuticals and organic materials1. The discovery of simpler, milder and more efficient approaches to organoborons can open additional routes to diverse substances2-5. Here we show a general method for the directed C-H borylation of arenes and heteroarenes without the use of metal catalysts. C7- and C4-borylated indoles are produced by a mild approach that is compatible with a broad range of functional groups. The mechanism, which is established by density functional theory calculations, involves BBr3 acting as both a reagent and a catalyst. The potential utility of this strategy is highlighted by the downstream transformation of the formed boron species into natural products and drug scaffolds.


Assuntos
Compostos de Boro/química , Compostos de Boro/síntese química , Boro/química , Produtos Biológicos/síntese química , Produtos Biológicos/química , Teoria da Densidade Funcional , Descoberta de Drogas , Indóis/química , Compostos Organometálicos/química , Preparações Farmacêuticas/síntese química , Preparações Farmacêuticas/química
3.
Med Res Rev ; 44(5): 2194-2235, 2024 09.
Artigo em Inglês | MEDLINE | ID: mdl-38591229

RESUMO

Metal complexes based on N-heterocyclic carbene (NHC) ligands have emerged as promising broad-spectrum antitumor agents in bioorganometallic medicinal chemistry. In recent decades, studies on cytotoxic metal-NHC complexes have yielded numerous compounds exhibiting superior cytotoxicity compared to cisplatin. Although the molecular mechanisms of these anticancer complexes are not fully understood, some potential targets and modes of action have been identified. However, a comprehensive review of their biological mechanisms is currently absent. In general, apoptosis caused by metal-NHCs is common in tumor cells. They can cause a series of changes after entering cells, such as mitochondrial membrane potential (MMP) variation, reactive oxygen species (ROS) generation, cytochrome c (cyt c) release, endoplasmic reticulum (ER) stress, lysosome damage, and caspase activation, ultimately leading to apoptosis. Therefore, a detailed understanding of the influence of metal-NHCs on cancer cell apoptosis is crucial. In this review, we provide a comprehensive summary of recent advances in metal-NHC complexes that trigger apoptotic cell death via different apoptosis-related targets or signaling pathways, including B-cell lymphoma 2 (Bcl-2 family), p53, cyt c, ER stress, lysosome damage, thioredoxin reductase (TrxR) inhibition, and so forth. We also discuss the challenges, limitations, and future directions of metal-NHC complexes to elucidate their emerging application in medicinal chemistry.


Assuntos
Antineoplásicos , Compostos Heterocíclicos , Metano , Humanos , Antineoplásicos/farmacologia , Antineoplásicos/química , Metano/análogos & derivados , Metano/química , Metano/farmacologia , Compostos Heterocíclicos/química , Compostos Heterocíclicos/farmacologia , Complexos de Coordenação/química , Complexos de Coordenação/farmacologia , Complexos de Coordenação/síntese química , Química Farmacêutica , Animais , Apoptose/efeitos dos fármacos , Neoplasias/tratamento farmacológico , Compostos Organometálicos/química , Compostos Organometálicos/farmacologia , Metais/química
4.
J Am Chem Soc ; 146(8): 5108-5117, 2024 02 28.
Artigo em Inglês | MEDLINE | ID: mdl-38367279

RESUMO

Enzymes are natural catalysts for a wide range of metabolic chemical transformations, including selective hydrolysis, oxidation, and phosphorylation. Herein, we demonstrate a strategy for the encapsulation of enzymes within a highly stable zirconium-based metal-organic framework. UiO-66-F4 was synthesized under mild conditions using an enzyme-compatible amino acid modulator, serine, at a modest temperature in an aqueous solution. Enzyme@UiO-66-F4 biocomposites were then formed by an in situ encapsulation route in which UiO-66-F4 grows around the enzymes and, consequently, provides protection for the enzymes. A range of enzymes, namely, lysozyme, horseradish peroxidase, and amano lipase, were successfully encapsulated within UiO-66-F4. We further demonstrate that the resulting biocomposites are stable under conditions that could denature many enzymes. Horseradish peroxidase encapsulated within UiO-66-F4 maintained its biological activity even after being treated with the proteolytic enzyme pepsin and heated at 60 °C. This strategy expands the toolbox of potential metal-organic frameworks with different topologies or functionalities that can be used as enzyme encapsulation hosts. We also demonstrate that this versatile process of in situ encapsulation of enzymes under mild conditions (i.e., submerged in water and at a modest temperature) can be generalized to encapsulate enzymes of various sizes within UiO-66-F4 while protecting them from harsh conditions (i.e., high temperatures, contact with denaturants or organic solvents).


Assuntos
Estruturas Metalorgânicas , Compostos Organometálicos , Ácidos Ftálicos , Estruturas Metalorgânicas/química , Zircônio/química , Biomimética , Compostos Organometálicos/química , Peroxidase do Rábano Silvestre
5.
J Am Chem Soc ; 146(1): 134-144, 2024 01 10.
Artigo em Inglês | MEDLINE | ID: mdl-38152996

RESUMO

Gd-L1 is a macrocyclic Gd-HPDO3A derivative functionalized with a short spacer to a trisulfonated pyrene. When compared to Gd-HPDO3A, the increased relaxivity appears to be determined by both the higher molecular weight and the occurrence of an intramolecularly catalyzed prototropic exchange of the coordinated OH moiety. In water, Gd-L1 displayed a relaxivity of 7.1 mM-1 s-1 (at 298 K and 0.5 T), slightly increasing with the concentration likely due to the onset of intermolecular aggregation. A remarkably high and concentration-dependent relaxivity was measured in human serum (up to 26.5 mM-1 s-1 at the lowest tested concentration of 0.005 mM). The acquisition of 1H-nuclear magnetic relaxation dispersion (NMRD) and 17O-R2 vs T profiles allowed to get an in-depth characterization of the system. In vitro experiments in the presence of human serum albumin, γ-globulins, and polylysine, as well as using media mimicking the extracellular matrix, provided strong support to the view that the trisulfonated pyrene fosters binding interactions with the exposed positive groups on the surface of proteins, responsible for a remarkable in vivo hyperintensity in T1w MR images. The in vivo MR images of the liver, kidneys, and spleen showed a marked contrast enhancement in the first 10 min after the i.v. injection of Gd-L1, which was 2-6-fold higher than that for Gd-HPDO3A, while maintaining a very similar excretion behavior. These findings may pave the way to an improved design of MRI GBCAs, for the first time, based on the setup of weak and dynamic interactions with abundant positive groups on serum and ECM proteins.


Assuntos
Meios de Contraste , Compostos Heterocíclicos , Compostos Organometálicos , Humanos , Meios de Contraste/química , Eletricidade Estática , Imageamento por Ressonância Magnética/métodos , Compostos Organometálicos/química , Pirenos , Gadolínio
6.
Chembiochem ; 25(17): e202400197, 2024 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-38940417

RESUMO

Water-soluble phthalocyanine (Pc) derivatives have been regarded as potential G-quadruplex (G4) nucleic acid-targeting ligands for anticancer therapy and have been extensively studied as effective photosensitizers for photodynamic therapy (PDT). Understanding how photosensitizers interact with nucleic acids and the subsequent photolytic reactions is essential for deciphering the initial steps of PDT, thereby aiding in the development of new photosensitizing agents. In this study, we found that red-light irradiation of a mixture of a Zn(II) Pc derivative and an all-parallel G4 DNA leads to catalytic and selective photodegradation of the DNA by reactive oxygen species (ROS) generated from the Zn(II) Pc derivative bound to DNA through a reaction mechanism similar to that of an enzyme reaction. This finding provides a novel insight into the molecular design of a photosensitizer to enhance its PDT efficacy.


Assuntos
DNA , Quadruplex G , Indóis , Isoindóis , Luz , Fotólise , Fármacos Fotossensibilizantes , Quadruplex G/efeitos dos fármacos , Indóis/química , Indóis/farmacologia , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/efeitos da radiação , DNA/química , Fotólise/efeitos da radiação , Catálise , Compostos Organometálicos/química , Compostos Organometálicos/farmacologia , Zinco/química , Zinco/farmacologia , Compostos de Zinco/química , Espécies Reativas de Oxigênio/metabolismo , Fotoquimioterapia , Luz Vermelha
7.
Chembiochem ; 25(17): e202400329, 2024 Sep 02.
Artigo em Inglês | MEDLINE | ID: mdl-38926093

RESUMO

Photodynamic therapy (PDT) is a noninvasive approach to cancer treatment, wherein cell death is initiated by singlet oxygen (1O2) production via energy transfer from excited photosensitizers to ground-state O2. Effective clinical photosensitizers necessitate water solubility for in vivo administration. Hydrophobic dyes, such as phthalocyanines, cannot be used directly as photosensitizers. Herein, we synthesized a myoglobin-(human serum albumin) fusion protein reconstituted with zinc-phthalocyanine (ZnPc), termed ZnPcMb-HSA. The photophysical properties of ZnPcMb-HSA closely resemble those of ZnPc-substituted Mb. Notably, ZnPc dissociates from ZnPcMb-HSA and selectively accumulates within cancer cells, while the protein components remain extracellular. Treatment of four distinct cell lines with ZnPcMb-HSA, followed by red-light irradiation, effectively induced apoptosis. The half-maximal inhibitory concentrations (IC50) against these cancer cell lines ranged between 0.1-0.5 µM. Reconstituted Mb-HSA emerges as a promising carrier for transporting various water-insoluble porphyrinoid photosensitizer to target cancer cells in PDT applications.


Assuntos
Indóis , Isoindóis , Mioglobina , Compostos Organometálicos , Fotoquimioterapia , Fármacos Fotossensibilizantes , Compostos de Zinco , Humanos , Indóis/química , Indóis/farmacologia , Mioglobina/química , Mioglobina/metabolismo , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/síntese química , Compostos Organometálicos/química , Compostos Organometálicos/farmacologia , Compostos Organometálicos/síntese química , Compostos de Zinco/química , Linhagem Celular Tumoral , Albumina Sérica Humana/química , Albumina Sérica Humana/metabolismo , Proteínas Recombinantes de Fusão/química , Proteínas Recombinantes de Fusão/farmacologia , Proteínas Recombinantes de Fusão/metabolismo , Apoptose/efeitos dos fármacos , Antineoplásicos/farmacologia , Antineoplásicos/química , Antineoplásicos/síntese química , Neoplasias/tratamento farmacológico , Neoplasias/patologia
8.
Bioconjug Chem ; 35(7): 883-889, 2024 Jul 17.
Artigo em Inglês | MEDLINE | ID: mdl-38914957

RESUMO

Development of bioconjugation strategies to efficiently modify biomolecules is of key importance for fundamental and translational scientific studies. Cysteine S-arylation is an approach which is becoming more popular due to generally rapid kinetics and high chemoselectivity, as well as the strong covalently bonded S-aryl linkage created in these processes. Organometallic approaches to cysteine S-arylation have been explored that feature many advantages compared to their more traditional organic counterparts. In this Viewpoint, progress in the use of Au(III) and Pd(II) oxidative addition (OA) complexes for stoichiometric cysteine S-arylation is presented and discussed. A focus is placed on understanding the rapid kinetics of these reactions under mild conditions, as well as the ability to generate biomolecular heterostructures. Potential avenues for further exploration are addressed and usefulness of these methods to the practitioner are emphasized in the discussion.


Assuntos
Cisteína , Oxirredução , Paládio , Cisteína/química , Ouro/química , Cinética , Compostos Organometálicos/química , Paládio/química
9.
Bioconjug Chem ; 35(6): 843-854, 2024 Jun 19.
Artigo em Inglês | MEDLINE | ID: mdl-38775802

RESUMO

The prevalence and fatality rates of gastric cancer (GC) remain elevated, with advanced stages presenting a grim prognosis. Noninvasive diagnosis of GC cancer often proves challenging until the disease has progressed to an advanced stage or metastasized. Initially, the level of fibronectin (FN) in cancer-associated fibroblasts (CAFs) of GC was at least 3.7 times higher than that in normal fibroblasts. Herein, two FN-targeting magnetic resonance/near-infrared fluorescence (MR/NIRF) imaging contrast agents were developed to detect GC and peritoneal metastasis noninvasively. The probes CREKA-Cy7-(Gd-DOTA) and CREKA-Cy7-(Gd-DOTA)3 demonstrated significant FN-targeting capability (with dissociation constants of 1.0 and 2.1 mM) and effective MR imaging performance (with proton relaxivity values of 9.66 and 27.44 mM-1 s-1 at 9.4 T, 37 °C). In vivo imaging revealed a high signal-to-noise ratio and successful visualization of GC metastasis using NIRF imaging as well as successful tumor detection in MR imaging. Therefore, this study highlights the potential of FN-targeting probes for GC diagnosis and aids in the advancement of new diagnostic strategies for the clinical detection of GC.


Assuntos
Meios de Contraste , Fibronectinas , Imageamento por Ressonância Magnética , Neoplasias Peritoneais , Neoplasias Gástricas , Neoplasias Gástricas/diagnóstico por imagem , Neoplasias Gástricas/patologia , Neoplasias Gástricas/diagnóstico , Fibronectinas/metabolismo , Imageamento por Ressonância Magnética/métodos , Neoplasias Peritoneais/secundário , Neoplasias Peritoneais/diagnóstico por imagem , Neoplasias Peritoneais/diagnóstico , Humanos , Meios de Contraste/química , Animais , Camundongos , Imagem Óptica/métodos , Compostos Organometálicos/química , Linhagem Celular Tumoral , Compostos Heterocíclicos
10.
Electrophoresis ; 45(11-12): 1018-1032, 2024 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-38279597

RESUMO

Over time, chiral organometallic compounds have attracted great interest in several fields, with applications going across several disciplines of chemical, biological, medical, and material sciences. In the last decades, due to advancements in molecular design and computational modeling, the chemistry of chiral transition metal complexes had a remarkable flowering, with the development of new structures for applications in asymmetric synthesis, bioinorganic chemistry, and molecular recognition. In these fields, fast chiral analysis to determine the enantiomeric purity of organometallic structures prepared by asymmetric synthesis, and for high-throughput screening of analytes, catalysts, and reactions, is very important. Capillary electrophoresis and related techniques proved to be extremely versatile for chiral analysis, showing unsurpassed advantages compared to chromatography like low consumption of materials, production of limited amounts of waste, fast equilibration, and possibility to replace easily type and concentration of the chiral selector, among others. Furthermore, electromigration techniques may be useful to gain details about the stereochemistry of the enantiomers of new compounds and to study analyte-selector noncovalent interactions at molecular level. On this basis, this short review aims to provide the reader with a comprehensive view on the enantioseparation of organometallic compounds by electromigration techniques, examining the topic from the historical perspective and showing what was made in this field so far, an essential know-how for developing new and advanced applications in the next future.


Assuntos
Eletroforese Capilar , Compostos Organometálicos , Estereoisomerismo , Compostos Organometálicos/química , Eletroforese Capilar/métodos
11.
J Biol Inorg Chem ; 29(5): 511-518, 2024 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-38926159

RESUMO

Antimicrobial resistance (AMR) has been emerging as a major global health threat and calls for the development of novel drug candidates. Metal complexes have been demonstrating high efficiency as antibacterial agents that differ substantially from the established types of antibiotics in their chemical structures and their mechanism of action. One strategy to exploit this potential is the design of metal-based hybrid organometallics that consist of an established antibiotic and a metal-based warhead that contributes an additional mechanism of action different from that of the parent antibiotic. In this communication, we describe the organometallic hybrid antibiotic 2c, in which the drug metronidazole is connected to a gold(I) N-heterocyclic carbene warhead that inhibits bacterial thioredoxin reductase (TrxR). Metronidazole can be used for the treatment with the obligatory anaerobic pathogen Clostridioides difficile (C. difficile), however, resistance to the drug hampers its clinical success. The gold organometallic conjugate 2c was an efficient inhibitor of TrxR and it was inactive or showed only minor effects against eucaryotic cells and bacteria grown under aerobic conditions. In contrast, a strong antibacterial effect was observed against both metronidazole-sensitive and -resistant strains of C. difficile. This report presents a proof-of-concept that the design of metal-based hybrid antibiotics can be a viable approach to efficiently tackle AMR.


Assuntos
Antibacterianos , Clostridioides difficile , Farmacorresistência Bacteriana , Ouro , Metano , Metronidazol , Testes de Sensibilidade Microbiana , Antibacterianos/farmacologia , Antibacterianos/química , Antibacterianos/síntese química , Clostridioides difficile/efeitos dos fármacos , Metronidazol/farmacologia , Metronidazol/química , Metano/análogos & derivados , Metano/química , Metano/farmacologia , Ouro/química , Farmacorresistência Bacteriana/efeitos dos fármacos , Tiorredoxina Dissulfeto Redutase/antagonistas & inibidores , Tiorredoxina Dissulfeto Redutase/metabolismo , Compostos Organometálicos/farmacologia , Compostos Organometálicos/química , Compostos Organometálicos/síntese química , Compostos Heterocíclicos/química , Compostos Heterocíclicos/farmacologia , Estrutura Molecular , Complexos de Coordenação/farmacologia , Complexos de Coordenação/química , Complexos de Coordenação/síntese química
12.
Chemistry ; 30(4): e202302484, 2024 Jan 16.
Artigo em Inglês | MEDLINE | ID: mdl-37870209

RESUMO

Cobaltabis(dicarbollides), ferrabis(dicarbollide), and their halogenated derivatives are the most studied metallacarboranes with great medical potential. These versatile compounds and their iodinated derivatives can be used in chemotherapy, radiotherapy, particle therapy, and bioimaging when isotopes are used. These metallacarboranes have been evaluated in vitro and recently in vivo with complex animal models. Lately, these studies have been complemented using the invertebrate Caenorhabditis elegans (C. elegans), a nematode largely used in toxicology. When evaluated at the L4 stage, cobaltabis(dicarbollides), ([o-COSAN]- and [8,8'-I2 -o-COSAN]- ), exhibited a higher mean lethal dose (LD50 ) than ferrabis(dicarbollides) ([o-FESAN]- and [8,8'-I2 -o-FESAN]- ). In this work, we used the C. elegans embryos since they are a complex biological barrier with concentric layers of polysaccharides and proteins that protect them from the environment. We assessed if the metal atom changes their biointeraction with the C. elegans embryos. First, we assessed the effects on embryo development for metallacarboranes and their di-iodinated derivatives. We observed changes in color and in their surface structure. An exhaustive physicochemical characterization was performed to understand better this interaction, revealing a stronger interaction of ferrabis(dicarbollide) compounds with C. elegans embryos than the cobaltabis(dicarbollide) molecules. Unveiling the biological interaction of these compounds is of great interest for their future biomedical applications.


Assuntos
Ânions , Caenorhabditis elegans , Compostos Organometálicos , Animais , Metais , Compostos Organometálicos/química , Cobalto/química
13.
Chemistry ; 30(28): e202400344, 2024 May 17.
Artigo em Inglês | MEDLINE | ID: mdl-38469901

RESUMO

[Gd(HP-DO3A)] (gadoteridol) as an active compound of ProHance® is a widely employed contrast agent in clinical MRI scans in the last 30 years. Recent concerns about the long-term retention of gadolinium-based contrast agents (GBCAs) led to a deeper investigation of the structural features underlying the integrity of the paramagnetic metal complex. Several human and nonclinical studies have noted marked differences among the macrocyclic GBCAs, with the least retention of Gd traces and most rapid elimination consistently being reported for [Gd(HP-DO3A)]. It was deemed of interest to assess how minor structural/electronic changes associated to the ligand structure may affect basic properties of the metal complex with several [Gd(HP-DO3A)] analogues synthesized and characterized in the last years. We recently reported that the closest homolog of [Gd(HP-DO3A)], i. e.: [Gd(HB-DO3A)], in which a (±)-2-hydroxy-1-propyl pendant arm is replaced by a (±)-2-hydroxy-1-butyl moiety, showed a significantly different retention behaviour in the model interaction with collagen, despite the apparently very minor structural difference. In this paper we report a comprehensive study of the structural, thermodynamic, kinetic and relaxation properties of [Gd(HB-DO3A)], compared to the parent [Gd(HP-DO3A)] and to other closely related macrocyclic GBCAs to assess whether very minor structural changes can modulate the physico-chemical properties of Gd3+ complexes.


Assuntos
Gadolínio , Compostos Heterocíclicos , Compostos Organometálicos , Humanos , Meios de Contraste/química , Complexos de Coordenação/química , Gadolínio/química , Compostos Heterocíclicos/química , Cinética , Ligantes , Imageamento por Ressonância Magnética , Compostos Organometálicos/química
14.
Mol Cell Biochem ; 479(3): 539-552, 2024 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-37106243

RESUMO

The role of carbon monoxide (CO) has evolved albeit controversial disputes on its toxicity. This biological gasotransmitter participates in the endogenous regulation of neurotransmitters and neuropeptides released in the nervous system. Exogenous CO gas inhalation at a lower concentration has been the subject of investigations, which have revealed its biological homeostatic mechanisms and protective effects against many pathological conditions. This therapeutic procedure of CO is, however, limited due to its immediate release, which favours haemoglobin at a high affinity with the subsequent generation of toxic carboxyhaemoglobin in tissues. In order to address this problem, carbon monoxide releasing molecule-2 (CORM-2) or also known as tricarbonyldichlororuthenium II dimer is developed to liberate a controlled amount of CO in the biological systems. In this review, we examine several potential mechanisms exerted by this therapeutic compound to produce the anti-nociceptive effect that has been demonstrated in previous studies. This review could shed light on the role of CORM-2 to reduce pain, especially in cases of chronic and neuropathic pain.


Assuntos
Gasotransmissores , Compostos Organometálicos , Monóxido de Carbono/farmacologia , Monóxido de Carbono/fisiologia , Compostos Organometálicos/química
15.
Analyst ; 149(10): 3041-3051, 2024 May 13.
Artigo em Inglês | MEDLINE | ID: mdl-38625079

RESUMO

Herein, we introduce a novel method for tryptophan detection via a reduction reaction facilitated by its interaction with a copper(II) phthalocyanine (CuPc) electrocatalytic electrode. This method addresses challenges associated with the susceptibility of the oxidation response to interference from various species when measuring tryptophan in bodily fluids. The reduction currents exhibit a linear increase with tryptophan concentrations in two ranges: 0.0013-0.10 mM and 0.10-1.20 mM, with the sensitivities of 14.7 ± 0.5 µA mM-1 and 3.5 ± 0.1 µA mM-1, respectively. The limit of detection (LOD, 3SB/m) is determined to be 0.39 µM. The sensor exhibits excellent reproducibility, with the relative standard deviation of <5%. Application of the sensor to authentic urine samples yields a % recovery of 101 ± 4%.


Assuntos
Técnicas Eletroquímicas , Eletrodos , Indóis , Limite de Detecção , Compostos Organometálicos , Triptofano , Triptofano/urina , Triptofano/química , Indóis/química , Humanos , Compostos Organometálicos/química , Catálise , Técnicas Eletroquímicas/métodos , Técnicas Eletroquímicas/instrumentação , Oxirredução , Isoindóis
16.
Inorg Chem ; 63(24): 10897-10914, 2024 Jun 17.
Artigo em Inglês | MEDLINE | ID: mdl-38795015

RESUMO

Contrast agents are important imaging probes in clinical MRI, allowing the identification of anatomic changes that otherwise would not be possible. Intensive research on the development of new contrast agents is being made to image specific pathological markers or sense local biochemical changes. The most widely used MRI contrast agents are based on gadolinium(III) complexes. Due to their very high charge density, they have low permeability through tight biological barriers such as the blood-brain barrier, hampering their application in the diagnosis of neurological disorders. In this study, we explore the interaction between the widely used contrast agent [Gd(DOTA)]- (Dotarem) and POPC lipid bilayers by means of molecular dynamics simulations. This metal complex is a standard reference where several chemical modifications have been introduced to improve key properties such as bioavailability and targeting. The simulations unveil detailed insights into the agent's interaction with the lipid bilayer, offering perspectives beyond experimental methods. Various properties, including the impact on global and local bilayer properties, were analyzed. As expected, the results indicate a low partition coefficient (KP) and high permeation barrier for this reference compound. Nevertheless, favorable interactions are established with the membrane leading to moderately long residence times. While coordination of one inner-sphere water molecule is maintained for the membrane-associated chelate, the physical-chemical attributes of [Gd(DOTA)]- as a MRI contrast agent are affected. Namely, increases in the rotational correlation times and in the residence time of the inner-sphere water are observed, with the former expected to significantly increase the water proton relaxivity. This work establishes a reference framework for the use of simulations to guide the rational design of new contrast agents with improved relaxivity and bioavailability and for the development of liposome-based formulations for use as imaging probes or theranostic agents.


Assuntos
Meios de Contraste , Bicamadas Lipídicas , Imageamento por Ressonância Magnética , Simulação de Dinâmica Molecular , Compostos Organometálicos , Meios de Contraste/química , Imageamento por Ressonância Magnética/métodos , Compostos Organometálicos/química , Compostos Organometálicos/síntese química , Bicamadas Lipídicas/química , Fosfatidilcolinas/química , Compostos Heterocíclicos
17.
Inorg Chem ; 63(25): 11667-11687, 2024 Jun 24.
Artigo em Inglês | MEDLINE | ID: mdl-38860314

RESUMO

Human African trypanosomiasis (HAT, sleeping sickness) and American trypanosomiasis (Chagas disease) are endemic zoonotic diseases caused by genomically related trypanosomatid protozoan parasites (Trypanosoma brucei and Trypanosoma cruzi, respectively). Just a few old drugs are available for their treatment, with most of them sharing poor safety, efficacy, and pharmacokinetic profiles. Only fexinidazole has been recently incorporated into the arsenal for the treatment of HAT. In this work, new multifunctional Ru(II) ferrocenyl compounds were rationally designed as potential agents against these pathogens by including in a single molecule 1,1'-bis(diphenylphosphino)ferrocene (dppf) and two bioactive bidentate ligands: pyridine-2-thiolato-1-oxide ligand (mpo) and polypyridyl ligands (NN). Three [Ru(mpo)(dppf)(NN)](PF6) compounds and their derivatives with chloride as a counterion were synthesized and fully characterized in solid state and solution. They showed in vitro activity on bloodstream T. brucei (EC50 = 31-160 nM) and on T. cruzi trypomastigotes (EC50 = 190-410 nM). Compounds showed the lowest EC50 values on T. brucei when compared to the whole set of metal-based compounds previously developed by us. In addition, several of the Ru compounds showed good selectivity toward the parasites, particularly against the highly proliferative bloodstream form of T. brucei. Interaction with DNA and generation of reactive oxygen species (ROS) were ruled out as potential targets and modes of action of the Ru compounds. Biochemical assays and in silico analysis led to the insight that they are able to inhibit the NADH-dependent fumarate reductase from T. cruzi. One representative hit induced a mild oxidation of low molecular weight thiols in T. brucei. The compounds were stable for at least 72 h in two different media and more lipophilic than both bioactive ligands, mpo and NN. An initial assessment of the therapeutic efficacy of one of the most potent and selective candidates, [Ru(mpo)(dppf)(bipy)]Cl, was performed using a murine infection model of acute African trypanosomiasis. This hit compound lacks acute toxicity when applied to animals in the dose/regimen described, but was unable to control parasite proliferation in vivo, probably because of its rapid clearance or low biodistribution in the extracellular fluids. Future studies should investigate the pharmacokinetics of this compound in vivo and involve further research to gain deeper insight into the mechanism of action of the compounds.


Assuntos
Compostos Ferrosos , Rutênio , Tripanossomicidas , Trypanosoma cruzi , Compostos Ferrosos/química , Compostos Ferrosos/farmacologia , Compostos Ferrosos/síntese química , Trypanosoma cruzi/efeitos dos fármacos , Ligantes , Tripanossomicidas/farmacologia , Tripanossomicidas/química , Tripanossomicidas/síntese química , Animais , Rutênio/química , Rutênio/farmacologia , Camundongos , Metalocenos/química , Metalocenos/farmacologia , Metalocenos/síntese química , Trypanosoma brucei brucei/efeitos dos fármacos , Testes de Sensibilidade Parasitária , Estrutura Molecular , Compostos Organometálicos/farmacologia , Compostos Organometálicos/química , Compostos Organometálicos/síntese química , Complexos de Coordenação/farmacologia , Complexos de Coordenação/química , Complexos de Coordenação/síntese química
18.
J Chem Inf Model ; 64(3): 775-784, 2024 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-38259142

RESUMO

Zr metallocenes have significant potential to be highly tunable polyethylene catalysts through modification of the aromatic ligand framework. Here we report the development of multiple machine learning models using a large library (>700 systems) of DFT-calculated zirconocene properties and barriers for ethylene polymerization. We show that very accurate machine learning models are possible for HOMO-LUMO gaps of precatalysts but the performance significantly depends on the machine learning algorithm and type of featurization, such as fingerprints, Coulomb matrices, smooth overlap of atomic positions, or persistence images. Surprisingly, the description of the bonding hapticity, the number of direct connections between Zr and the ligand aromatic carbons, only has a moderate influence on the performance of most models. Despite robust models for HOMO-LUMO gaps, these types of machine learning models based on structure connectivity type features perform poorly in predicting ethylene migratory insertion barrier heights. Therefore, we developed several relatively robust and accurate machine learning models for barrier heights that are based on quantum-chemical descriptors (QCDs). The quantitative accuracy of these models depends on which potential energy surface structure QCDs were harvested from. This revealed a Hammett-type principle to naturally emerge showing that QCDs from the π-coordination complexes provide much better descriptions of the transition states than other potential-energy structures. Feature importance analysis of the QCDs provides several fundamental principles that influence zirconocene catalyst reactivity.


Assuntos
Compostos Organometálicos , Zircônio , Ligantes , Compostos Organometálicos/química , Etilenos/química , Aprendizado de Máquina
19.
Chem Rev ; 122(9): 8841-8883, 2022 05 11.
Artigo em Inglês | MEDLINE | ID: mdl-35266711

RESUMO

Bisimine derivatives of salicylaldehyde with chiral diamines (salens) are privileged ligands in asymmetric organometallic catalysis, which can be used in cooperation with organocatalysts as additives. The latter can be a modifier of the metal reactivity by liganding or a true co-catalyst working in tandem or in a dual system. All scenarios encountered in the literature are reviewed and classified according to the organocatalyst. In each case, mechanistic and physical-organic chemistry considerations are discussed to better understand the gears of these complex catalytic settings.


Assuntos
Compostos Organometálicos , Catálise , Etilenodiaminas/química , Ligantes , Compostos Organometálicos/química
20.
Nanotechnology ; 35(47)2024 Sep 03.
Artigo em Inglês | MEDLINE | ID: mdl-39173645

RESUMO

Drug-loaded polymeric micelles have proven to be highly effective carrier systems for the efficient delivery of hydrophobic photosensitizers (PSs) in photodynamic therapy (PDT). This study introduces the micellization potential of poly(oligoethylene glycol methyl ether methacrylate) (pOEGMA) as a novel approach, utilizing the hydrophobic methacrylate segments of pOEGMA to interact with highly hydrophobic zinc phthalocyanine (ZnPc), thereby forming a potential micellar drug carrier system. The ZnPc molecule was synthesized from phthalonitrile derivatives and its fluorescence, photodegradation, and singlet oxygen quantum yields were determined in various solvents. In solvents such as tetrahydrofuran, dimethyl sulfoxide, and N,N-dimethylformamide, the ZnPc compound exhibited the requisite photophysical and photochemical properties for PDT applications. The pOEGMA homopolymer was synthesized via reversible addition-fragmentation chain-transfer polymerization, while ZnPc-loaded pOEGMA micelles were prepared using the nanoprecipitation method. Characterization of the pOEGMA, ZnPc, and micelles was conducted using FTIR,1H-NMR, dynamic light scattering, matrix-assisted laser desorption/ionization time-of-flight mass spectrometries, gel permeation chromatography, and transmission electron microscopy. The critical micelle concentration was determined to be 0.027 mg ml-1using fluorescence spectrometry. The drug loading and encapsulation efficiencies of the ZnPc-loaded micelles were calculated to be 0.67% and 0.47%, respectively. Additionally, the release performance of ZnPc from pOEGMA micelles was monitored over a period of nearly 10 d, while the lyophilized micelles exhibited stability for 3 months. Lastly, the ZnPc-loaded micelles were more biocompatible than ZnPc on L929 cell line. The results suggest that the pOEGMA homopolymer possesses the capability to micellize through its methacrylate segments when interacting with highly hydrophobic molecules, presenting a promising avenue for enhancing the delivery efficiency of hydrophobic PSs in PDT. Moreover, it was also deciphered that obtained formulations were highly biocompatible according to cytotoxicity results and could be safely employed as drug delivery systems in further applications.


Assuntos
Portadores de Fármacos , Indóis , Isoindóis , Micelas , Compostos Organometálicos , Fotoquimioterapia , Fármacos Fotossensibilizantes , Polietilenoglicóis , Compostos de Zinco , Fármacos Fotossensibilizantes/química , Fármacos Fotossensibilizantes/farmacologia , Fármacos Fotossensibilizantes/administração & dosagem , Indóis/química , Compostos de Zinco/química , Compostos Organometálicos/química , Polietilenoglicóis/química , Portadores de Fármacos/química , Sobrevivência Celular/efeitos dos fármacos , Oxigênio Singlete/química , Interações Hidrofóbicas e Hidrofílicas
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA