RESUMO
Azithromycin (AZM) is a macrolide-type antibiotic used to prevent and treat serious infections (mycobacteria or MAC) that significantly inhibit bacterial growth. Knowledge of the predominant conformation in solution is of fundamental importance for advancing our understanding of the intermolecular interactions of AZM with biological targets. We report an extensive density functional theory (DFT) study of plausible AZM structures in solution considering implicit and explicit solvent effects. The best match between the experimental and theoretical nuclear magnetic resonance (NMR) profiles was used to assign the preferred conformer in solution, which was supported by the thermodynamic analysis. Among the 15 distinct AZM structures, conformer M14, having a short intramolecular C6-OH N H-bond, is predicted to be dominant in water and dimethyl sulfoxide (DMSO) solutions. The results indicated that the X-ray structure backbone is mostly conserved in solution, showing that large flexible molecules with several possible conformations may assume a preferential spatial orientation in solution, which is the molecular structure that ultimately interacts with biological targets.
RESUMO
Azithromycin (AZM) is a well-known macrolide-type antibiotic that has been used in the treatment of infections and inflammations. Knowledge of the predominant molecular structure in solution is a prerequisite for an understanding of the interactions of the drug in biological media. Experimental structural determination can be carried out for samples in solid-state (X-ray diffraction technique) and gas phase (electron diffraction experiment). In solution, spectroscopic methods can be used to extract valuable information which combined with quantum chemical calculations can lead to the determination of the preferred molecular structures to be observed when a given solute is dissolved in each solvent. That is precisely the aim of this work. We used experimental NMR chemical shift data (in CDCl3) as a reference for comparison with Density Functional Theory (DFT) NMR calculations, with geometry optimized having as guess input two crystallographic structures available in the literature with the configuration of all chiral carbon atoms inverted, named here A and B. The Polarizable Continuum Model (PCM) was used to describe the solvent effects (chloroform) including five explicit CHCl3 solvent molecules, which we believe can account for short and long-range solute-solvent interactions. Analysis of calculated thermodynamic, NMR chemical shift, MAE (Mean Absolute Error), and spin-spin coupling constant values revealed that both supposable C3R-C5S (named M2-A) and C3S-C5R (named M2-B) structures are equally probable to exist in chloroform solution. In addition, we found that the heavy atoms' conformation is reasonably similar in the solid-state and chloroform solution; however, regarding the OH groups, the spatial orientations are rather different with intramolecular OHâ¯N and OHâ¯O hydrogen bonds present in solution and with some of them being absent in the X-ray structure probably due to crystal packing effects.
Assuntos
Azitromicina , Clorofórmio , Antibacterianos , Carbono , Teoria Quântica , Soluções , Solventes/química , TermodinâmicaRESUMO
This work describes the synthesis, characterization and in vitro anticancer activity of two platinum(II) complexes of the type [Pt(L1)2(1,10-phen)] 1 and [Pt(L2)2(1,10-phen)] 2, where L1 = 5-heptyl-1,3,4-oxadiazole-2-(3H)-thione, L2 = 5-nonyl-1,3,4-oxadiazole-2-(3H)-thione and 1,10-phen = 1,10-phenanthroline. As to the structure of these complexes, the X-ray structural analysis of 1 indicates that the geometry around the platinum(II) ion is distorted square-planar, where two 5-alkyl-1,3,4-oxadiazol-2-thione derivatives coordinate a platinum(II) ion through the sulfur atom. A chelating bidentate phenanthroline molecule completes the coordination sphere. We tested these complexes in two breast cancer cell lines, namely, MCF-7 (a hormone responsive cancer cell) and MDA-MB-231 (triple negative breast cancer cell). In both cells, the most lipophilic platinum compound, complex 2, was more active than cisplatin, one of the most widely used anticancer drugs nowadays. DNA binding studies indicated that such complexes are able to bind to ct-DNA with Kb values of 104 M-1. According to data from dichroism circular and fluorescence spectroscopy, these complexes appear to bind to the DNA in a non-intercalative, probably via minor groove. Molecular docking followed by semiempirical simulations indicated that these complexes showed favorable interactions with the minor groove of the double helix of ct-DNA in an A-T rich region. Thereafter, flow cytometry analysis showed that complex 2 induced apoptosis and necrosis in MCF-7 cells.
Assuntos
Antineoplásicos , Complexos de Coordenação , Humanos , Fenantrolinas/farmacologia , Fenantrolinas/química , Platina/química , Tionas , Simulação de Acoplamento Molecular , Antineoplásicos/química , DNA/química , Complexos de Coordenação/química , Linhagem Celular TumoralRESUMO
The drugs currently used to treat leishmaniases have limitations concerning cost, efficacy, and safety, making the search for new therapeutic approaches urgent. We found that the gold(I)-derived complexes were active against L. infantum and L. braziliensis intracellular amastigotes with IC50 values ranging from 0.5 to 5.5 µM. All gold(I) complexes were potent inhibitors of trypanothione reductase (TR), with enzyme IC50 values ranging from 1 to 7.8 µM. Triethylphosphine-derived complexes enhanced reactive oxygen species (ROS) production and decreased mitochondrial respiration after 2 h of exposure, indicating that gold(I) complexes cause oxidative stress by direct ROS production, by causing mitochondrial damage or by impairing TR activity and thus accumulating ROS. There was no cross-resistance to antimony; in fact, SbR (antimony-resistant mutants) strains were hypersensitive to some of the complexes. BALB/c mice infected with luciferase-expressing L. braziliensis or L. amazonensis and treated orally with 12.5 mg/kg/day of AdT Et (3) or AdO Et (4) presented reduced lesion size and parasite burden, as revealed by bioimaging. The combination of (3) and miltefosine allowed for a 50% reduction in miltefosine treatment time. Complexes 3 and 4 presented favorable pharmacokinetic and toxicity profiles that encourage further drug development studies. Gold(I) complexes are promising antileishmanial agents, with a potential for therapeutic use, including in leishmaniasis caused by antimony-resistant parasites.
Assuntos
Antiprotozoários/farmacologia , Ouro/farmacologia , Leishmaniose , NADH NADPH Oxirredutases/antagonistas & inibidores , Animais , Leishmaniose/tratamento farmacológico , Camundongos , Camundongos Endogâmicos BALB C , Estresse OxidativoRESUMO
Bacteria belonging to Mycobacterium avium complex are organisms of low pathogenicity that infect immunosuppressed individuals. Infection is treated with an antimicrobial macrolide, Clarithromycin (CAM) or Azitromycin, associated with Ethambutol and Rifabutin during 12 months. Regimen long duration and side effects hinder patient's commitment to treatment favoring emergence of antibiotic resistance. In this present study, we evaluated the activity of JVA, an Isoniazid (INH) derivative, against M. avium 2447, a clinical isolate. We demonstrated that JVA reduces M. avium 2447 growth in macrophages, more efficiently than CAM and INH. In order to explore JVA mechanism of action, we investigated compound properties and performed pH-dependent stability studies. Our results suggest an enhanced ability of JVA to cross biological membranes. Furthermore, we suggest that in acidic conditions of macrophages' phagosomes, where mycobacteria replicate, JVA would be promptly hydrolyzed to INH, delivering the adduct INH-nicotinamide adenine dinucleotide and thus inhibiting M. avium 2447 growth.
Assuntos
Antituberculosos/farmacologia , Isoniazida/análogos & derivados , Complexo Mycobacterium avium/efeitos dos fármacos , Infecção por Mycobacterium avium-intracellulare/tratamento farmacológico , Análise de Variância , Animais , Hidrazonas/farmacologia , Macrófagos/microbiologia , Camundongos Endogâmicos C57BL , Testes de Sensibilidade Microbiana , Complexo Mycobacterium avium/crescimento & desenvolvimentoRESUMO
In order to improve the previously observed antichagasic activity of Cu(II) complexes containing 2-chlorobenzhydrazide (2-CH), we report herein the synthesis and anti-Trypanosoma cruzi activity of novel copper complexes containing 2-methoxybenzhydrazide (2-MH), 4-methoxybenzhydrazide (4-MH) and three α-diimine ligands, namely, 1,10-phenanthroline (phen), 2,2-bipyridine (bipy) and 4-4'-dimethoxy-2-2'-bipyridine (dmb). Two of these complexes showed higher in vitro anti-Trypanosoma cruzi activity when compared to benznidazole, the main drug used in Chagas disease treatment. One of them, the copper complex with 4-MH and dmb, [Cu(4-MH)(dmb)(ClO4)2], exhibited a higher selectivity index than that recommended for preclinical studies. Considering this observation, complex [Cu(4-MH)(dmb)(ClO4)2] was selected for preliminary in vivo assays, which verified that this compound was able to reduce parasitemia by 64% at the peak of infection. Further investigations were performed on all compounds. The Cu(II) complexes bind to ct-DNA with Kb values in the range of 103-104 M-1, with [Cu(4-MH)(dmb)(ClO4)2] showing the highest Kb value (1.45 × 104 M-1). Molecular docking simulations predicted that [Cu(4-MH)(dmb)(ClO4)2] binds in the minor groove of the double helix of ct-DNA and forms one hydrogen bond.
Assuntos
Doença de Chagas/tratamento farmacológico , Cobre/química , Tripanossomicidas/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Animais , Doença de Chagas/parasitologia , Complexos de Coordenação , Feminino , Hidrazinas/síntese química , Hidrazinas/farmacologia , Ligação de Hidrogênio , Ligantes , Camundongos , Camundongos Endogâmicos BALB C , Simulação de Acoplamento Molecular , Nitroimidazóis/farmacologia , Piridinas/síntese química , Piridinas/farmacologia , Tripanossomicidas/síntese químicaRESUMO
In this paper, density functional theory calculations of nuclear magnetic resonance (NMR) chemical shifts for l-quebrachitol isomer, previously studied in our group, are reported with the aim of investigating in more detail the water solvent effect on the prediction of 1H NMR spectra. In order to include explicit water molecules, 20 water-l-quebrachitol configurations obtained from Monte Carlo simulation were selected to perform geometry optimizations using the effective fragment potential method encompassing 60 water molecules around the solute. The solvated solute optimized geometries were then used in B3LYP/6-311+G(2d,p) NMR calculations with PCM-water. The inclusion of explicit solvent in the B3LYP NMR calculations resulted in large changes in the 1H NMR profiles. We found a remarkable improvement in the agreement with experimental NMR profiles when the explicit hydrated l-quebrachitol structure is used in B3LYP 1H NMR calculations, yielding a mean absolute error (MAE) of only 0.07 ppm, much lower than reported previously for the gas phase optimized structure (MAE = 0.11 ppm). In addition, a very improved match between theoretical and experimental 1H NMR spectrum measured in D2O was achieved with the new hydrated optimized l-quebrachitol structure, showing that a fine-tuning of the theoretical NMR spectra can be accomplished once solvent effects are properly considered.
RESUMO
The current anticancer and antileishmanial drug arsenal presents several limitations concerning their specificity, efficacy, costs and the emergence of drug-resistant cells lines, which encourages the urgent need to search for new alternatives. Inspired by the fact that gold(I)-based compounds are promising antitumoral and antileishmanial drug candidates, we synthesized novel gold(I) complexes containing phosphine and 5-phenyl-1,3,4-oxadiazole-2-thione and evaluated their anticancer and antileishmanial activities. Synthesis was performed by reacting 5-phenyl-1,3,4-oxadiazole-2-thione derivatives with chloro(triphenylphosphine)gold(I) and chloro(triethylphosphine)gold(I). The novel compounds were characterized by infrared, Raman, 1H, 13C nuclear magnetic resonance, high-resolution mass spectra, and x-ray crystallography. The coordination of the ligands to gold(I) occurred through the exocyclic sulfur atom. All gold(I) complexes were active at low micromolar or nanomolar range with IC50 values ranging from <0.10 to 1.66 µM against cancer cell lines and from 0.9 to 4.2 µM for Leishmania infantum intracellular amastigotes. Compound (6-A) was very selective against murine melanoma B16F10, colon cancer CT26.WT cell lines and L. infantum intracellular amastigotes. Compound (7-B) presented the highest anticancer activity against both cancer cell lines while the promising antileishmanial lead was compound (6-A). Tiethylphosphine gold(I) complexes were more active than the conterparts triphenylphosphine derivatives for both anticancer and antileishmanial activities. Triethylphosphine gold(I) derivatives presented antimony cross-resistance in L. guyanensis demonstrating their potential to be used as chemical tools to better understand mechanisms of drug resistance and action. These findings revealed the anticancer and antileishmanial potential of gold(I) oxadiazole phosphine derivatives.
Assuntos
Desenho de Fármacos , Ouro/química , Leishmania infantum/efeitos dos fármacos , Compostos Organoáuricos/química , Compostos Organoáuricos/farmacologia , Oxidiazóis/química , Fosfinas/química , Antimônio/farmacologia , Antineoplásicos/química , Antineoplásicos/farmacologia , Antiprotozoários/química , Antiprotozoários/farmacologia , Linhagem Celular Tumoral , Resistência a Medicamentos/efeitos dos fármacos , HumanosRESUMO
Three series of d-galactose derivatives linked to a lipophilic aminoalcohol moiety were synthesized and their antibacterial activity was evaluated against Mycobacterium tuberculosis and representative species of Gram positive and Gram negative bacteria. Five out of the thirteen tested compounds displayed activity against M. tuberculosis, with a minimal inhibitory concentration (MIC) of 12.5 µg/mL and seven compounds were active against the four bacterial strains tested. The best results were obtained for amino alcohols 10 and 11 against Staphylococcus epidermidis (MIC = 2 µg/mL). The antitumor activity was evaluated against three tumor cell lines (MCF-7, HeLa and MO59J) and compared to the normal cell line GM07492A. The results showed that the lowest IC50 values were observed for the amino alcohol 16 against MCF-7 (11.9 µM) and MO59J (10.0 µM).
Assuntos
Amino Álcoois/farmacologia , Antibacterianos/farmacologia , Antineoplásicos/farmacologia , Amino Álcoois/síntese química , Amino Álcoois/química , Antibacterianos/síntese química , Antibacterianos/química , Antineoplásicos/síntese química , Antineoplásicos/química , Linhagem Celular Tumoral , Proliferação de Células/efeitos dos fármacos , Relação Dose-Resposta a Droga , Ensaios de Seleção de Medicamentos Antitumorais , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Humanos , Testes de Sensibilidade Microbiana , Estrutura Molecular , Relação Estrutura-AtividadeRESUMO
A simple and mild method is demonstrated for assembling acyl carbamates through a base-free four-component Pd-catalyzed carbonylation of aryl halides in the presence of potassium cyanate and alcohols in a two-chamber system. This approach produces a wide range of aryl acyl carbamates in good to excellent yields from the corresponding aryl bromides or iodides with near-stoichiometric carbon monoxide. In addition, the method can be extended to the synthesis of primary amides thereby expanding the usefulness of cyanate as an ammonia equivalent.
Assuntos
Álcoois/química , Carbamatos/síntese química , Cianatos/química , Hidrocarbonetos Halogenados/química , Paládio/química , Amidas/química , Amônia/química , Carbamatos/química , Catálise , Estrutura MolecularRESUMO
A useful method was developed for the synthesis of active esters by palladium-catalyzed alkoxycarbonylation of (hetero)aromatic bromides. The protocol was general for a range of oxygen nucleophiles including N-hydroxysuccinimide (NHS), pentafluorophenol (PFP), hexafluoroisopropyl alcohol (HFP), 4-nitrophenol, and N-hydroxyphthalimide. A high functional group tolerance was displayed, and several active esters were prepared with good to excellent isolated yields. The protocol was extended to access an important synthetic precursor to the HIV-protease inhibitor, saquinavir, by formation of an NHS ester followed by acyl substitution.
Assuntos
Brometos/química , Inibidores da Protease de HIV/química , Inibidores da Protease de HIV/síntese química , Hidrocarbonetos Halogenados/química , Paládio/química , Ftalimidas/química , Saquinavir/química , Saquinavir/síntese química , Succinimidas/química , Catálise , Ésteres , Estrutura MolecularRESUMO
The isoflavone genistein 1 and some derivatives modulate IL-12, TNF-α and NO production by macrophages and lung cancer cell lines, and improve the clinical signs of experimental autoimmune encephalomyelitis (EAE). Seven genistein derivatives connected at C-6 position of a sugar, such as d-glucose and d-galactose, were synthesized. The ability to modulate macrophage response was evaluated, showing variable inhibition capacity of NO and TNF-α production in J774.A1 and RAW 264.7. Five of the seven compounds were non-cytotoxic; compound 8 was more effective to inhibit NO and TNF-α production, without affecting cell viability.
Assuntos
Galactose/química , Genisteína/química , Genisteína/farmacologia , Glucose/química , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Óxido Nítrico/biossíntese , Animais , Linhagem Celular , Sobrevivência Celular/efeitos dos fármacos , Genisteína/síntese química , Interferon gama/farmacologia , Lipopolissacarídeos/farmacologia , Macrófagos/citologia , Camundongos , Fator de Necrose Tumoral alfa/biossínteseRESUMO
Me-ß-cyclodextrin (Me-ßCD) and HP-ß-cyclodextrin (HP-ßCD) inclusion complexes with isoniazid (INH) were prepared with the aim of modulating the physicochemical and biopharmaceutical properties of the guest molecule, a well-known antibuberculosis drug. The architectures of the complexes were initially proposed according to NMR data Job plot and ROESY followed by density functional theory (DFT) calculations of (1)H NMR spectra using the PBE1PBE functional and 6-31G(d,p) basis set, including the water solvent effect with the polarizable continuum model (PCM), for various inclusion modes, providing support for the experimental proposal. An analysis of the (1)H NMR chemical shift values for the isoniazid (H6',8' and H5',9') and cyclodextrins (H3,5) C(1)H hydrogens, which are known to be very adequately described by the DFT methodology, revealed them to be extremely useful, promptly confirming the inclusion complex formation. An included mode which describes Me-ßCD partially enclosing the hydrazide group of the INH is predicted as the most favorable supramolecular structure that can be used to explain the physicochemical properties of the encapsulated drug. Antibacterial activity was also evaluated, and the results indicated the inclusion complexes are a potential strategy for tuberculosis treatment.
Assuntos
Antibacterianos/farmacologia , Corpos de Inclusão/química , Isoniazida/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , beta-Ciclodextrinas/farmacologia , Antibacterianos/síntese química , Antibacterianos/química , Varredura Diferencial de Calorimetria , Relação Dose-Resposta a Droga , Isoniazida/química , Espectroscopia de Ressonância Magnética , Testes de Sensibilidade Microbiana , Prótons , Teoria Quântica , Relação Estrutura-Atividade , beta-Ciclodextrinas/químicaRESUMO
Polyamines are substances involved in many aspects of cell growth, division, and differentiation. Because of the metabolic differences between host cells and parasite cells, polyamine metabolism has been considered as a potential target for the chemotherapy of parasitic diseases. The aim of this work was to evaluate the schistosomicidal activity of different N-alkylated diamines (3a-3h), amino alcohols (4a-4d), and glycosylated amino alcohols (10a-10d). Compounds were prepared by synthetic methods and submitted to in vitro evaluation against adult worms of Schistosoma mansoni. At 100 µM, 3b, 3e, and 3h as well as 4a, 4b, 4d, 10a, 10b, and 10d resulted in 100% mortality of adult schistosomes. Compound 3d (12.5 to 100 µM) caused the death of 100% of both male and female adult schistosomes, while 3f (12.5 to 100 µM) resulted in 100% mortality of only male adult worms, whereas no mortality in female worms was observed. Compounds 3d and 3f were also able to reduce viability and decrease production of developed eggs in comparison with the negative control group. Diamines 3d and 3f may represent useful lead compounds for further optimization in order to develop new schistosomicidal agents.
Assuntos
Amino Álcoois/administração & dosagem , Diaminas/administração & dosagem , Schistosoma mansoni/efeitos dos fármacos , Esquistossomicidas/administração & dosagem , Amino Álcoois/química , Animais , Diaminas/química , Humanos , Poliaminas/química , Esquistossomose/tratamento farmacológico , Esquistossomose/patologia , Esquistossomicidas/químicaRESUMO
Mitoxantrone is an anthracenedione antineoplastic and immunosuppressive agent approved for multiple sclerosis treatment. Novel mono- and disubstituted anthraquinone derivatives, analogues of mitoxantrone, were synthesized through the addition of lipophilic amino alcohols and evaluated for their effect on IL-1ß, TNF-α and nitric oxide production by LPS/IFN-γ-stimulated RAW264.7 cells. The disubstituted 1,4-anthracene-9,10-dione 10 showed significant inhibition of nitric oxide, TNF-α and IL-1ß production at the concentration of 5 µg/mL, with a much lower cytotoxicity than mitoxantrone. The monosubstituted 3, 4, 11, 12 and 13 also displayed a moderate to good inhibitory capacity on IL-1ß production. However, the methylated compounds 11, 12 and 13 failed to inhibit the TNF-α production, and compound 13 was the only one to decrease the production of nitric oxide. None of these derivatives was toxic at the tested concentrations. Compounds 10 and 13 had better inhibitory capacity of the inflammatory mediators analyzed, with reliable viability of the cells.
Assuntos
Antracenos/farmacologia , Interleucina-1beta/metabolismo , Macrófagos/efeitos dos fármacos , Óxido Nítrico/metabolismo , Fator de Necrose Tumoral alfa/metabolismo , Animais , Linhagem Celular , Macrófagos/metabolismo , CamundongosRESUMO
Leishmanicidal and trypanocidal activity of seventeen lipophilic diamines was evaluated in vitro against Leishmania braziliensis, L. chagasi, and Trypanosoma cruzi. Twelve compounds presented anti-Leishmania and six showed anti-T. cruzi amastigote activity. Compound 14 (N-tetradecyl-1,4-butanediamine) was the most active against both L. braziliensis (IC50 = 2.6 µm) and L. chagasi (IC50 = 3.0 µm) which showed a selectivity index (SI) >100. N-decyl-1,6-hexanediamine (compound 9) presented an IC50 = 1.6 µm and SI >187 and was over six times more potent than the reference drug benznidazole against T. cruzi. Treatment of infected or uninfected macrophages with compounds 9 and 14 did not induce significant TNFα and NO production. Four compounds (15, 16, 22, and 23) inhibited 78.9%, 77.7%, 83.7%, and 70.1% of rTRLb activity, respectively, and compound 23 inhibited 73.3% of rTRTc activity at 100 µm. A concentration-dependent effect on mitochondrial membrane depolarization was observed in T. cruzi epimastigotes treated with compound 9, suggesting this mechanism may be involved in the trypanocidal effect. On the contrary, in L. braziliensis promastigotes treated with compound 14, no mitochondrial depolarization was observed. Our results demonstrate that N-decyl-1,6-hexanediamine and N-tetradecyl-1,4-butanediamine are promising molecules for the development of novel leading compounds against T. cruzi and Leishmania spp., particularly given a possible alternative mechanism of action.
Assuntos
Diaminas/farmacologia , Leishmania/efeitos dos fármacos , Tripanossomicidas/farmacologia , Trypanosoma cruzi/efeitos dos fármacos , Animais , Células da Medula Óssea/citologia , Sobrevivência Celular/efeitos dos fármacos , Diaminas/química , Macrófagos/efeitos dos fármacos , Macrófagos/metabolismo , Macrófagos/parasitologia , Potencial da Membrana Mitocondrial/efeitos dos fármacos , Camundongos , Camundongos Endogâmicos BALB C , Óxido Nítrico/metabolismo , Tripanossomicidas/química , Fator de Necrose Tumoral alfa/metabolismoRESUMO
Mitoxantrone is an anthracene-based anticancer agent whose efficacy in treating autoimmune diseases is believed to be due to cytotoxicity and inhibition of proliferation of cells. Several novel anthraquinone derivatives, analogs of mitoxantrone, were designed and synthesized. Lipophilic and functionalized mitoxantrone analogs were prepared by a simple methodology and the cytotoxicity and the inhibitory effect on nitric oxide release of these compounds were demonstrated in vitro on J774A.1 macrophages. Interestingly compounds 3, 4, 5, 6, 7, and 8 exhibited reduction in NO release (62.4%, 92.6%, 73.4%, 58.4%, 57.8% and 53.4%, respectively) in comparison to NG-n-methyl-arginine treated control, without cytotoxicity. In conclusion, anthraquinone derivatives were prepared in a good yield and showed promissory antiinflammatory properties.
Assuntos
Antraquinonas/toxicidade , Macrófagos/efeitos dos fármacos , Animais , Antraquinonas/química , Anti-Inflamatórios/química , Anti-Inflamatórios/toxicidade , Linhagem Celular , Proliferação de Células/efeitos dos fármacos , Humanos , Estrutura Molecular , Óxido Nítrico/biossínteseRESUMO
The early diagnosis of diseases related to phosphate metabolism is very important for preventing, in most cases, severe kidney failure and cardiovascular events that have an increased risk of death. In this work, we present biofunctionalized quantum dots (b-QDs) prepared with chitosan and its chemically modified derivatives to detect and capture phosphate in water media. Chitosan (CHI), N,N,N-trimethylchitosan (TMC) and carboxymethylchitosan (CMC) were used as ligands for producing colloidal CdS nanocrystals in aqueous systems. UV-Visible spectroscopy (UV-Vis), photoluminescence spectroscopy (PL), fluorescence microscopy, Raman spectroscopy, Fourier transform infrared spectroscopy (FTIR), zeta potential analysis (ZP), and transmission electron microscopy (TEM) were used to characterize the colloidal QDs. Additionally, in vitro assays based on the b-QDs were designed and used to evaluate phosphate ion adsorption. The results clearly indicated that chitosan and chitosan derivatives were effective in nucleating and stabilizing CdS QDs in aqueous colloidal suspensions with an average nanocrystal size ranging from 2.2 to 3.6 nm. The photoluminescent behavior of the CdS bioconjugates was highly dependent on the chemical functionality introduced in the chitosan-derivative polymer. Moreover, the presence of different chemical groups in chitosan significantly affected the capacity of the bioconjugates to bind phosphates. Finally, a "pseudo in vivo" assay was designed using an artificial biomembrane based on phospholipid bilayers to preliminarily assess the possibility of using the bioconjugates to biolabel cell membranes. Therefore, a new class of fluorescent biosorbent nano-hybrids was developed using chemically functionalized chitosan conjugated to quantum dots for potential applications in biochemical analysis and nanomedicine.
RESUMO
Density functional theory (DFT) calculations of (1) H NMR chemical shifts for l-quebrachitol isomers were performed using the B3LYP functional employing the 6-31G(d,p) and 6-311 + G(2d,p) basis sets. The effect of the solvent on the B3LYP-calculated NMR spectrum was accounted for using the polarizable continuum model. Comparison is made with experimental (1) H NMR spectroscopic data, which shed light on the average uncertainty present in DFT calculations of chemical shifts and showed that the best match between experimental and theoretical B3LYP (1) H NMR profiles is a good strategy to assign the molecular structure present in the sample handled in the experimental measurements. Among four plausible O-methyl-inositol isomers, the l-quebrachitol 2a structure was unambiguously assigned based only on the comparative analysis of experimental and theoretical (1) H NMR chemical shift data. The B3LYP infrared (IR) spectrum was also calculated for the four isomers and compared with the experimental data, with analysis of the theoretical IR profiles corroborating assignment of the 2a structure. Therefore, it is confirmed in this study that a combined experimental/DFT spectroscopic investigation is a powerful tool in structural/conformational analysis studies.
Assuntos
Inositol/análogos & derivados , Teoria Quântica , Configuração de Carboidratos , Inositol/química , Espectroscopia de Ressonância Magnética/normas , Prótons , Padrões de Referência , EstereoisomerismoRESUMO
Thalidomide is used to treat a variety of diseases including erythema nodosum leprosum, an inflammatory complication of leprosy. However, this drug has severe teratogenic activity and novel thalidomide analogues might be used to treat diseases without this severe side effect. A series of diamine compounds containing two hydrolyzed phthalimide units were chosen as analogues of thalidomide and evaluated regarding their capacity to regulate the production of molecules involved in inflammatory responses. TNF-α, IL-12 and IL-10 production, and the expression of CD80 and CD86 were investigated in LPS plus IFN-γ-stimulated J774A.1 cells by ELISA and flow cytometry, respectively. The expression of TNF-α and IL-10 mRNA was analyzed by real time RT-PCR. TNF-α, IL-6, IFN-γ, CXCL9 and CXCL10 production by human peripheral blood mononuclear cells (PBMC) were evaluated by flow cytometry. Compounds 3, 6 and 9 greatly inhibited TNF-α and IL-12 production while enhancing IL-10. In addition, CD80 expression was inhibited, but not CD86. The compounds inhibited TNF-α production by PBMC more than thalidomide and also had an inhibitory effect on the production of IL-6, IFN-γ, CXCL9 and CXCL10. Levels of mRNA for TNF-α were reduced after treatment with the compounds, suggesting post- transcriptional effects. The compounds had no effect on cell viability. Our results indicate that the novel diamine compounds 3, 6 and 9 inhibit critical pro-inflammatory cytokines and stimulate IL-10, which make them attractive candidate drugs for the treatment of certain inflammatory conditions and cancer.