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1.
Arch Biochem Biophys ; 730: 109398, 2022 11 15.
Artículo en Inglés | MEDLINE | ID: mdl-36116504

RESUMEN

Oryzalin (ORY) is a dinitroaniline derivative that inhibits the microtubule polymerization in plants and parasitic protozoa by selectively binding to the α-tubulin subunit. This herbicidal agent exhibits good antiprotozoal activity against major human parasites, such as Toxoplasma gondii (toxoplasmosis), Leishmania mexicana (leishmaniasis), and Plasmodium falciparum (malaria). Previous chemical mutagenesis assays on T. gondii α-tubulin (TgAT) have identified key mutations that lead to ORY resistance. Herein, we employed alchemical free energy methods and molecular dynamics simulations to determine if the ORY resistance mutations either decrease the TgAT's affinity of the compound or increase the protein stability. Our results here suggest that L136F and V202F mutations significantly decrease the affinity of ORY to TgAT, while T239I and V252L mutations diminish TgAT's flexibility. On the other hand, protein stability predictors determined that R243S mutation reduces TgAT stability due to the loss of its salt bridge interaction with E27. Interestingly, molecular dynamics simulations confirm that the loss of this key interaction leads to ORY binding site closure. Our study provides a better insight into the TgAT-ORY interaction, further supporting our recently proposed ORY-binding site.


Asunto(s)
Toxoplasma , Humanos , Toxoplasma/genética , Toxoplasma/metabolismo , Tubulina (Proteína)/química , Dinitrobencenos/química , Dinitrobencenos/metabolismo , Dinitrobencenos/farmacología , Sitios de Unión
2.
J Mol Biol ; 434(8): 167513, 2022 04 30.
Artículo en Inglés | MEDLINE | ID: mdl-35218770

RESUMEN

We have previously developed a universal chimeric antigen receptor (CAR), which recognizes dinitrophenyl (DNP) and can redirect T and NK cells to target cancer and HIV antigens using DNP-conjugated antibodies as adaptor molecules. However, the DNP-antibody conjugates are generated by random modification, which may not be optimal for this modular system. Here, we report the development of enhanced adaptor molecules by site-specific DNP modification. We use the genetic code expansion technology to generate single-chain fragment variable (scFv) antibodies with site-specific DNP. We compare four anti-CD19 scFv mutants and find that the one with DNP at the flexible peptide linker between VL and VH is the most effective in redirecting anti-DNP CAR-T cells against CD19+ cells. The other three mutants are ineffective in doing so due to reduced DNP exposure or abrogated CD19 binding. We also use the anti-CD22 scFv as another model adaptor molecule and again find that the peptide linker is ideal for DNP derivatization. Our approach can potentially be used to design enhanced adaptor molecules to redirect the DNP-mediated universal CAR against other tumor antigens.


Asunto(s)
Dinitrobencenos , Inmunoterapia Adoptiva , Neoplasias , Receptores Quiméricos de Antígenos , Anticuerpos de Cadena Única , Antígenos CD19/genética , Antígenos de Neoplasias/genética , Antígenos de Neoplasias/inmunología , Línea Celular Tumoral , Dinitrobencenos/química , Humanos , Neoplasias/inmunología , Neoplasias/terapia , Receptores Quiméricos de Antígenos/genética , Receptores Quiméricos de Antígenos/inmunología , Anticuerpos de Cadena Única/genética , Linfocitos T/inmunología , Linfocitos T/trasplante
3.
J Biol Chem ; 297(4): 101143, 2021 10.
Artículo en Inglés | MEDLINE | ID: mdl-34473996

RESUMEN

Nitroreductases are emerging as attractive bioremediation enzymes, with substrate promiscuity toward both natural and synthetic compounds. Recently, the nitroreductase NfnB from Sphingopyxis sp. strain HMH exhibited metabolic activity for dinitroaniline herbicides including butralin and pendimethalin, triggering the initial steps of their degradation and detoxification. However, the determinants of the specificity of NfnB for these herbicides are unknown. In this study, we performed structural and biochemical analyses of NfnB to decipher its substrate specificity. The homodimer NfnB is a member of the PnbA subgroup of the nitroreductase family. Each monomer displays a central α + ß fold for the core domain, with a protruding middle region and an extended C-terminal region. The protruding middle region of Val75-Tyr129 represents a structural extension that is a common feature to members of the PnbA subgroup and functions as an opening wall connecting the coenzyme FMN-binding site to the surface, therefore serving as a substrate binding site. We performed mutational, kinetic, and structural analyses of mutant enzymes and found that Tyr88 in the middle region plays a pivotal role in substrate specificity by determining the dimensions of the wall opening. The mutation of Tyr88 to phenylalanine or alanine caused significant changes in substrate selectivity toward bulkier dinitroaniline herbicides such as oryzalin and isopropalin without compromising its activity. These results provide a framework to modify the substrate specificity of nitroreductase in the PnbA subgroup, which has been a challenging issue for its biotechnological and bioremediation applications.


Asunto(s)
Compuestos de Anilina/química , Dinitrobencenos/química , Herbicidas/química , Nitrorreductasas/química , Sphingomonadaceae/enzimología , Sulfanilamidas/química , Sitios de Unión , Relación Estructura-Actividad , Especificidad por Sustrato
4.
Molecules ; 26(16)2021 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-34443401

RESUMEN

The dinitrotoluene isomers 2,4 and 2,6-dinitrotoluene (DNT) represent highly toxic, mutagenic, and carcinogenic compounds used in explosive manufacturing and in commercial production of polyurethane foam. Bioremediation, the use of microbes to degrade residual DNT in industry wastewaters, represents a promising, low cost and environmentally friendly alternative technology to landfilling. In the present study, the effect of different bioremediation strategies on the degradation of DNT in a microcosm-based study was evaluated. Biostimulation of the indigenous microbial community with sulphur phosphate (2.3 g/kg sludge) enhanced DNT transformation (82% transformation, from 300 g/L at Day 0 to 55 g/L in week 6) compared to natural attenuation over the same period at 25 °C. The indigenous microbial activity was found to be capable of transforming the contaminant, with around 70% transformation of DNT occurring over the microcosm study. 16S rDNA sequence analysis revealed that while the original bacterial community was dominated by Gammaproteobacteria (30%), the addition of sulphur phosphate significantly increased the abundance of Betaproteobacteria by the end of the biostimulation treatment, with the bacterial community dominated by Burkholderia (46%) followed by Rhodanobacter, Acidovorax and Pseudomonas. In summary, the results suggest biostimulation as a treatment choice for the remediation of dinitrotoluenes and explosives waste.


Asunto(s)
Biodegradación Ambiental , Sustancias Explosivas/toxicidad , Microbiota/genética , Aguas del Alcantarillado/microbiología , Burkholderia/química , Burkholderia/genética , Burkholderia/aislamiento & purificación , Burkholderia/metabolismo , Dinitrobencenos/química , Dinitrobencenos/toxicidad , Sustancias Explosivas/química , Humanos , Pseudomonas/química , Pseudomonas/genética , Pseudomonas/aislamiento & purificación , Pseudomonas/metabolismo , ARN Ribosómico 16S/genética
5.
Mol Pharm ; 18(7): 2647-2656, 2021 07 05.
Artículo en Inglés | MEDLINE | ID: mdl-34160225

RESUMEN

Building on clinical case reports of the abscopal effect, there has been considerable interest in the synergistic effects of radiation and immunotherapies for the treatment of cancer. Here, the first radiolabeled antibody-recruiting small molecule that can chelate a variety of cytotoxic radionuclides is described. The platform consists of a tunable antibody-binding domain against a serum antibody of interest (e.g., dinitrophenyl hapten) to recruit endogenous antibodies that activate effector cell function, a chelate capable of binding diagnostic and therapeutic radiometals, and a tetrazine for bioorthogonal coupling with trans-cyclooctene-modified targeting vectors. The dinitrophenyl-tetrazine ligand was shown to both affect dose-dependent antibody recruitment and immune cell function (phagocytosis) in vitro, and the bisphosphonate 177Lu-complex was shown to accumulate at sites of calcium accretion in vivo, which was achieved using both active and pretargeting strategies.


Asunto(s)
Anticuerpos Monoclonales/química , Anticuerpos Monoclonales/farmacocinética , Calcio/metabolismo , Dinitrobencenos/química , Lutecio/química , Radiofármacos/química , Bibliotecas de Moléculas Pequeñas/química , Animales , Femenino , Ratones , Ratones Endogámicos BALB C , Fagocitosis , Distribución Tisular
6.
J Med Chem ; 64(8): 4947-4959, 2021 04 22.
Artículo en Inglés | MEDLINE | ID: mdl-33825469

RESUMEN

Hapten-specific endogenous antibodies are naturally occurring antibodies present in human blood. Herein, we investigated a new strategy in which small-molecule haptens were utilized as naturally occurring antibody binders for peptide half-life extension. The glucagon-like peptide 1 receptor agonist exendin 4 was site-specifically functionalized with the dinitrophenyl (DNP) hapten at the C-terminus via sortase A-mediated ligation. The resulting Ex4-DNP conjugates retained GLP-1 receptor activation potency in vitro and had a similar in vivo acute glucose-lowering effect comparable to that of native Ex4. Pharmacokinetic studies and hypoglycemic duration tests demonstrated that the Ex4-DNP conjugates displayed significantly elongated half-lives and improved long-acting antidiabetic activity in the presence of endogenous anti-DNP antibodies. In chronic treatment studies, once-daily administration of optimal conjugate 7 demonstrated more beneficial effects without prominent toxicity compared with Ex4. This strategy provides a new approach and represents an alternative to the well-established peptide-Fc fusion strategy to improve the peptide half-life and the therapeutic efficacy.


Asunto(s)
Anticuerpos/sangre , Exenatida/química , Haptenos/química , Hipoglucemiantes/síntesis química , Secuencia de Aminoácidos , Animales , Anticuerpos/inmunología , Complejo Antígeno-Anticuerpo/química , Complejo Antígeno-Anticuerpo/metabolismo , Glucemia/análisis , Diabetes Mellitus Experimental/tratamiento farmacológico , Dinitrobencenos/química , Dinitrobencenos/inmunología , Diseño de Fármacos , Femenino , Receptor del Péptido 1 Similar al Glucagón/agonistas , Receptor del Péptido 1 Similar al Glucagón/metabolismo , Prueba de Tolerancia a la Glucosa , Semivida , Haptenos/inmunología , Hipoglucemiantes/metabolismo , Hipoglucemiantes/uso terapéutico , Hígado/efectos de los fármacos , Hígado/metabolismo , Hígado/patología , Ratones , Ratones Endogámicos C57BL
7.
Phytomedicine ; 82: 153407, 2021 Feb.
Artículo en Inglés | MEDLINE | ID: mdl-33571899

RESUMEN

BACKGROUND: Atopic dermatitis is a chronic inflammatory skin disease in humans. Although Olea europaea leaf extract (OLE) and Spirodela polyrhiza extract (SPE) have been used to protect against skin damage, the effects of their combined administration on atopic dermatitis have yet to studied. PURPOSE: In this study, we evaluated the potential therapeutic effects of an OLE and SPE combination on the progression of atopic dermatitis and the possible mechanisms underlying these effects in 1-chloro-2,4-dinitrobenzene (DNCB)-treated NC/Nga mice. METHODS: Atopic dermatitis was induced by topical application of 0.2% w/v DNCB prepared in an olive oil:acetone solution (1:3), and thereafter OLE, SPE and OLE + SPE were administered orally for 5 weeks. We determined atopic dermatitis symptoms, serum IgE levels, and levels of cytokine- and gene expression in the dorsal skin and splenocytes, and performed histological and immune cell subtype analyses. The expression of skin barrier-related proteins (filaggrin, sirtuin 1, and claudin 1) was also evaluated. RESULTS: The OLE + SPE combination significantly ameliorated atopic dermatitis symptoms, including dermatitis scores, and reduced epidermal thickness and infiltration of different inflammatory cells in mice with DNCB-induced atopic dermatitis. It also significantly reduced the number of CD4+, CD8+, and CD4+/CD69+ T cells; immunoglobulin E-producing B cells (CD23+/B220+) in the axillary lymph nodes; CD3+ T-cell eosinophils (chemokine-chemokine receptor 3+/CD11b+) in the skin; and CD3+ T cells, immunoglobulin E-producing B cells (CD23+/B220+), and eosinophils in peripheral blood mononuclear cells. Additionally, the experimental combination lowered levels of serum immunoglobulin E and histamine, as well as Th2-mediated cytokines, and interleukin-4, -5, and -13, whereas it increased the levels of Th1-mediated cytokine interferon-γ in splenocytes. Furthermore, the preparation significantly restored expression of the skin barrier-related proteins filaggrin, sirtuin 1, and claudin 1, and also reduced the expression of the inflammatory cytokine interleukin-6 and chemokine-chemokine receptor 3, as well as the pruritus-related cytokine interleukin-31 and interleukin-31 receptor, in atopic dermatitis skin lesions. CONCLUSION: Taken together, our findings indicate that administration of a combination of OLE and SPE can alleviate atopic dermatitis symptoms by regulating immune balance and skin barrier function and may be an effective therapeutic option for the treatment of atopic dermatitis.


Asunto(s)
Dermatitis Atópica/tratamiento farmacológico , Dinitrobencenos/toxicidad , Olea/química , Extractos Vegetales/uso terapéutico , Piel/efectos de los fármacos , Animales , Citocinas/metabolismo , Dinitrobencenos/química , Modelos Animales de Enfermedad , Proteínas Filagrina , Inmunoglobulina E/sangre , Proteínas de Filamentos Intermediarios/metabolismo , Leucocitos Mononucleares/metabolismo , Masculino , Ratones , Extractos Vegetales/farmacología , Piel/metabolismo , Células Th2/efectos de los fármacos
9.
J Am Soc Mass Spectrom ; 31(3): 547-552, 2020 Mar 04.
Artículo en Inglés | MEDLINE | ID: mdl-32126775

RESUMEN

The formation and radical-directed dissociation of multiple hydrogen-abstracted peptide cations [M + H - mH]·+ has been reported using MALDI-ISD with dinitro-substituted matrices. The MALDI-ISD of synthetic peptides using 3,5-dinitrosalicylic acid (3,5-DNSA) and 3,4-dinitrobenzoic acid (3,4-DNBA) as matrices resulted in multiple hydrogen abstraction from the analyte [M + H]+ and fragment [a]+ ions, i.e., [M + H - mH]+ and [a - mH]+ (m = 1-8). All of the ISD spectra showed unusually intense [a]+ ions originating from cleavage at the Cα-C bond of the Leu-Xxx residues when peptides without Phe/Tyr/His/Cys residues were used. The intensity of the [an]+ series ions generated using 3,5-DNSA and 3,4-DNBA rapidly decreased with increasing residue number n, suggesting cleavage at multiradical sites of [M + H - mH]•+. It was suggested that multiple hydrogen abstraction from protonated peptides [M + H]+ mainly takes place from the backbone amide nitrogen.


Asunto(s)
Péptidos/química , Espectrometría de Masa por Láser de Matriz Asistida de Ionización Desorción/métodos , Secuencia de Aminoácidos , Cationes/análisis , Dinitrobencenos/química , Hidrógeno/análisis , Nitrobenzoatos/química , Salicilatos/química
10.
Spectrochim Acta A Mol Biomol Spectrosc ; 229: 118003, 2020 Mar 15.
Artículo en Inglés | MEDLINE | ID: mdl-31923786

RESUMEN

Biological thiols including homocysteine (Hcy), cysteine (Cys), hydrogen sulfide (H2S) and glutathione (GSH) play crucial roles in various pathological and physiological processes. The development of optical probes for biothiols has been an active research area in recent years. Herein, a new turn-on fluorescence probe (HD-NBD) was designed and synthesized by fusing tetrahydro[5]helicene and 7-nitro-2,1,3-benzoxadiazole (NBD) for simultaneous discrimination of Hcy/Cys, H2S and GSH in aqueous solution. This probe is able to show unique absorbance enhancement at 548 nm for H2S and additional fluorescence enhancement at 536 nm only for Cys/Hcy, which can be used to discriminate H2S, Cys/Hcy and GSH simultaneously. In addition, HD-NBD also shows low background without any self-fluorescence, as well as high selectivity toward common biothiols. The low detection limits of this probe are about 0.15 µM for Hcy with a wide linear range (1-80 µM), 0.36 µM for Cys (linear range: 1-45 µM), 0.79 µM for H2S (linear range: 1-80 µM) and 4.44 µM for GSH (linear range: 1-60 µM). Moreover, HD-NBD can identify Hcy/Cys, H2S from GSH and other amino acids with high sensitivity and selectivity, therefore it could be used for detecting endogenous and exogenous Hcy/Cys under biological condition.


Asunto(s)
Neoplasias de la Mama/metabolismo , Cisteína/análisis , Colorantes Fluorescentes/química , Glutatión/análisis , Homocisteína/análisis , Sulfuro de Hidrógeno/análisis , Neoplasias de la Mama/patología , Dinitrobencenos/química , Femenino , Humanos , Oxadiazoles/química , Compuestos Policíclicos/química , Células Tumorales Cultivadas
11.
J Sci Food Agric ; 100(2): 648-655, 2020 Jan 30.
Artículo en Inglés | MEDLINE | ID: mdl-31577839

RESUMEN

BACKGROUND: Several diseases and insects may cause damage to the normal growth of cucumber. Azoxystrobin and meptyldinocap, because of their novel mode of action, are effective against pathogens that have developed reduced sensitivity to other fungicides. Azoxystrobin is persistent in various crops and environments. However, there is a lack of research on the dissipation of these two pesticides, especially meptyldinocap. RESULTS: Analytes could be quantified with decent recoveries of 90-101%, with relative standard deviations (RSDs) of 3.0-10.1%. The terminal residues of meptyldinocap and azoxystrobin in cucumber were all < limit of quantification (LOQ) (0.02 and 0.05 mg kg-1 ). The half-lives of meptyldinocap and azoxystrobin were 0.8-1.1 and 1.2-2.8 days, respectively. The processing factors (PFs) for washing were all < 1, but the removal rate for washing was < 29.0%. Peeling had a significant effect on the removal of pesticide. The largest residue reductions were noticed through the pickling process, but special care should be taken regarding residues in the pickling solution as pesticides could transfer to them from cucumber. A more interesting finding was that the degradation of two pesticides was accelerated by the addition of calcium oxide. CONCLUSION: Pesticide residues on cucumber decreased after these processes. These results enable the health-risks from dietary exposures to pesticide residues to be characterized. They enable maximum residue limits (MRLs) to be established for pesticide residues in food products. They also assist the optimization of food processing with regard to pesticide residue dissipation. © 2019 Society of Chemical Industry.


Asunto(s)
Cucumis sativus/química , Dinitrobencenos/química , Fungicidas Industriales/química , Residuos de Plaguicidas/química , Pirimidinas/química , Estrobilurinas/química , Contaminación de Alimentos/análisis , Frutas/química , Cinética
12.
J Med Chem ; 62(17): 8115-8139, 2019 09 12.
Artículo en Inglés | MEDLINE | ID: mdl-31393122

RESUMEN

We report herein the discovery of 3,5-dinitrophenyl 1,2,4-triazoles with excellent and selective antimycobacterial activities against Mycobacterium tuberculosis strains, including clinically isolated multidrug-resistant strains. Thorough structure-activity relationship studies of 3,5-dinitrophenyl-containing 1,2,4-triazoles and their trifluoromethyl analogues revealed the key role of the position of the 3,5-dinitrophenyl fragment in the antitubercular efficiency. Among the prepared compounds, the highest in vitro antimycobacterial activities against M. tuberculosis H37Rv and against seven clinically isolated multidrug-resistant strains of M. tuberculosis were found with S-substituted 4-alkyl-5-(3,5-dinitrophenyl)-4H-1,2,4-triazole-3-thiols and their 3-nitro-5-(trifluoromethyl)phenyl analogues. The minimum inhibitory concentrations of these compounds reached 0.03 µM, which is superior to all the current first-line anti-tuberculosis drugs. Furthermore, almost all compounds with excellent antimycobacterial activities exhibited very low in vitro cytotoxicities against two proliferating mammalian cell lines. The docking study indicated that these compounds acted as the inhibitors of decaprenylphosphoryl-ß-d-ribofuranose 2'-oxidase enzyme, which was experimentally confirmed by two independent radiolabeling experiments.


Asunto(s)
Oxidorreductasas de Alcohol/antagonistas & inhibidores , Antituberculosos/farmacología , Proteínas Bacterianas/antagonistas & inhibidores , Desarrollo de Medicamentos , Mycobacterium tuberculosis/efectos de los fármacos , Oxidorreductasas de Alcohol/metabolismo , Antituberculosos/síntesis química , Antituberculosos/química , Proteínas Bacterianas/metabolismo , Dinitrobencenos/síntesis química , Dinitrobencenos/química , Dinitrobencenos/farmacología , Relación Dosis-Respuesta a Droga , Hidrocarburos Fluorados/síntesis química , Hidrocarburos Fluorados/química , Hidrocarburos Fluorados/farmacología , Modelos Moleculares , Estructura Molecular , Mycobacterium tuberculosis/enzimología , Relación Estructura-Actividad , Triazoles/síntesis química , Triazoles/química , Triazoles/farmacología
13.
Chem Commun (Camb) ; 55(73): 10952-10955, 2019 Sep 10.
Artículo en Inglés | MEDLINE | ID: mdl-31441915

RESUMEN

Triggering antibody-mediated innate immune mechanisms to kill cancer cells is an attractive therapeutic avenue. In this context, recruitment of endogenous antibodies to the cancer cell surface could be a viable alternative to the use of monoclonal antibodies. We report on antibody-recruiting polymers containing multiple antibody-binding hapten motifs and cyclooctynes that can covalently conjugate to azides introduced onto the glycocalyx of cancer cells by metabolic labeling with azido sugars.


Asunto(s)
Resinas Acrílicas/química , Anticuerpos/inmunología , Azidas/metabolismo , Dinitrobencenos/inmunología , Hexosaminas/metabolismo , Resinas Acrílicas/síntesis química , Animales , Azidas/química , Línea Celular Tumoral , Química Clic , Reacción de Cicloadición , Ciclooctanos/síntesis química , Ciclooctanos/química , Dinitrobencenos/síntesis química , Dinitrobencenos/química , Fluorescencia , Colorantes Fluorescentes/química , Glicocálix/metabolismo , Hexosaminas/química , Humanos , Ratones , Microscopía Confocal/métodos , Microscopía Fluorescente/métodos , Prueba de Estudio Conceptual , Esferoides Celulares/metabolismo
14.
Int J Mol Sci ; 20(13)2019 Jul 01.
Artículo en Inglés | MEDLINE | ID: mdl-31266213

RESUMEN

Seven cobalt(II) complexes of pyrazole derivatives and dinitrobenzoate ligands were synthesized and characterized. The single-crystal X-ray diffraction structure was determined for one of the ligands and one of the complexes. The analysis and spectral data showed that all the cobalt complexes had octahedral geometries, which was supported by DFT calculations. The complexes and their free ligands were evaluated against fungal strains of Candida albicans and emerging non-albicans species and epimastigotes of Trypanosoma cruzi. We obtained antifungal activity with a minimum inhibitory concentration (MIC) ranging from 31.3 to 250 µg mL-1. The complexes were more active against C. krusei, showing MIC values between 31.25 and 62.5 µg mL-1. In addition, some ligands (L1-L6) and complexes (5 and Co(OAc)2 · 4H2O) significantly reduced the yeast to hypha transition of C. albicans at 500 µg mL-1 (inhibition ranging from 30 to 54%). Finally, the complexes and ligands did not present trypanocidal activity and were not toxic to Vero cells. Our results suggest that complexes of cobalt(II) with ligands derived from pyrazoles and dinitrobenzoate may be an attractive alternative for the treatment of diseases caused by fungi, especially because they target one of the most important virulence factors of C. albicans.


Asunto(s)
Antibacterianos/farmacología , Candida albicans/efectos de los fármacos , Cobalto/química , Dinitrobencenos/farmacología , Pirazoles/farmacología , Animales , Antibacterianos/síntesis química , Antibacterianos/química , Supervivencia Celular , Chlorocebus aethiops , Complejos de Coordinación/síntesis química , Complejos de Coordinación/química , Complejos de Coordinación/farmacología , Cristalografía por Rayos X , Dinitrobencenos/síntesis química , Dinitrobencenos/química , Ligandos , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Pirazoles/síntesis química , Pirazoles/química , Relación Estructura-Actividad , Células Vero
15.
Methods Mol Biol ; 2030: 263-275, 2019.
Artículo en Inglés | MEDLINE | ID: mdl-31347124

RESUMEN

The determination of the stereochemistry of common and unusual amino acids is important in food chemistry, archeology, medicine, and life sciences including such diverse areas as marine biology and extraterrestrial chemistry and has greatly contributed to our current knowledge in these fields.To determine the stereochemistry of amino acids, many chromatographic methods have been developed and refined over the last decades. Here we describe a state-of-the-art indirect chromatography-based LC-MS method. Diastereomers were formed from amino acids that were reacted with chiral derivatizing agents such as Marfey's reagent (FDAA), GITC, S-NIFE, and OPA-IBLC and separated on a reversed phase column using mass spectrometry compatible buffers.


Asunto(s)
Aminoácidos/análisis , Espectrometría de Masas/métodos , Péptidos/análisis , Alanina/análogos & derivados , Alanina/química , Aminoácidos/química , Tampones (Química) , Cromatografía Líquida de Alta Presión/instrumentación , Cromatografía Líquida de Alta Presión/métodos , Dinitrobencenos/química , Hidrólisis , Isotiocianatos/química , Espectrometría de Masas/instrumentación , Nitrocompuestos/química , Péptidos/química , Estereoisomerismo
16.
Environ Sci Pollut Res Int ; 26(23): 24223-24234, 2019 Aug.
Artículo en Inglés | MEDLINE | ID: mdl-31230245

RESUMEN

Elucidation of the interaction between NACs and smectites is important to the understanding of the potential for transport of nitroaromatic compounds (NACs) in soils and to implementation of NAC-contaminated soil remediation. The adsorption of dinitrotoluene isomers (DNTs) and substituted dinitrobenzenes (SDNBs) by smectite was determined by batch equilibration and characterized by FTIR and XPS, along with molecular dynamics simulations. The adsorption of DNTs differed substantially among the isomers, attributed to the overall degree of nitro deflection relative to the aromatic ring plane. The substituents in SDNBs strengthened the electrostatic interaction between smectite K+ and nitro groups, facilitating SDNB adsorption to smectite. The competition between 2,4-DNT and 1,3-DNB, as well as the inclusion complexation of K+ by crown ether 18c6e, both reduced 2,4-DNT adsorption to smectite by weakening the K+-nitro interaction. All the results demonstrated that the electrostatic interaction between smectite K+ and nitro of NACs was the predominant force in mediating their adsorption. This was supported by FTIR spectra that the N-O bands shifted due to the weakening of N-O bonds and strengthening of C-N bonds via the electron transfer to cations. The XPS of smectite further manifested the cation-nitro interactions that the binding energies of K 2p 1/2, K 2p 3/2, and Si 2p shifted higher with 1,3-DNB adsorbed. Molecular dynamics simulations indicated the aromatic planes of 2,4-DNP and 2,4-DNAs were parallel to the basal plane of smectite and the oxygens of nitro groups in the molecules were directly coordinated with smectite K+.


Asunto(s)
Dinitrobencenos/química , Silicatos/química , Contaminantes del Suelo/química , Adsorción , Cationes/química , Arcilla , Modelos Químicos , Suelo
17.
Biomacromolecules ; 20(7): 2796-2808, 2019 07 08.
Artículo en Inglés | MEDLINE | ID: mdl-31244019

RESUMEN

The development of more efficient photosensitizers with minimal damage to surrounding normal tissues has been a valuable and challenging subject during photodynamic therapy (PDT). Herein, a stimuli-activated porphyrinic photosensitizer (PEG-TPP-DNB; PEG = poly(ethylene glycol); TPP = 5,10,15,20-tetraphenylporphyrin; DNB = 2,4-dinitrobenzene) with capabilities of fluorescence and, remarkably, singlet oxygen quenching was prepared successfully for photodynamic therapy with high efficiency and biosecurity. The amphiphilic PEG-TPP-DNB could be self-assembled into nanomicelles in aqueous media and dissociated in response to reductive thiol such as glutathione. Meanwhile, the fluorescence and singlet oxygen generation of porphyrinic photosensitizer would be activated to regenerate. Moreover, the intracellular uptake and localization effectively confirmed the redox-responsive and activated behavior of PEG-TPP-DNB micelles. The cytotoxicity in vitro revealed that the micelles had low dark toxicity and great phototoxicity, and in vivo bioimaging and antitumor evaluation further indicated that the micelles possessed selective tumor imaging and targeted PDT antitumor effect as well as low systemic toxicity. Overall, this tumor microenvironment-activated photosensitizer system may provide a useful strategy for precise photodynamic therapy.


Asunto(s)
Neoplasias/terapia , Fotoquimioterapia , Fármacos Fotosensibilizantes/química , Tensoactivos/química , Proliferación Celular/efectos de los fármacos , Dinitrobencenos/química , Dinitrobencenos/farmacología , Humanos , Micelas , Neoplasias/patología , Oxidación-Reducción/efectos de los fármacos , Oxígeno/metabolismo , Fármacos Fotosensibilizantes/uso terapéutico , Polietilenglicoles/química , Polietilenglicoles/farmacología , Porfirinas/química , Porfirinas/farmacología , Tensoactivos/uso terapéutico
18.
Molecules ; 24(8)2019 Apr 18.
Artículo en Inglés | MEDLINE | ID: mdl-31003443

RESUMEN

Feeding experiments with stable isotopes are helpful tools for investigation of metabolic fluxes and biochemical pathways. For assessing nitrogen metabolism, the heavier nitrogen isotope, [15N], has been frequently used. In plants, it is usually applied in form of [15N]-nitrate, which is assimilated mainly in leaves. Thus, methods for quantification of the [15N]-nitrate/[14N]-nitrate ratio in leaves are useful for the planning and evaluation of feeding and pulse-chase experiments. Here we describe a simple and sensitive method for determining the [15N]-nitrate to [14N]-nitrate ratio in leaves. Leaf discs (8 mm diameter, approximately 10 mg fresh weight) were sufficient for analysis, allowing a single leaf to be sampled multiple times. Nitrate was extracted with hot water and derivatized with mesitylene in the presence of sulfuric acid to nitromesitylene. The derivatization product was analyzed by gas chromatography-mass spectrometry with electron ionization. Separation of the derivatized samples required only 6 min. The method shows excellent repeatability with intraday and interday standard deviations of less than 0.9 mol%. Using the method, we show that [15N]-nitrate declines in leaves of hydroponically grown Crassocephalum crepidioides, an African orphan crop, with a biological half-life of 4.5 days after transfer to medium containing [14N]-nitrate as the sole nitrogen source.


Asunto(s)
Asteraceae/química , Cromatografía de Gases y Espectrometría de Masas/métodos , Nitratos/análisis , Isótopos de Nitrógeno/química , Benceno/química , Derivados del Benceno/química , Calibración , Dinitrobencenos/química , Cinética , Extractos Vegetales/análisis , Hojas de la Planta/química , Estándares de Referencia
19.
Spectrochim Acta A Mol Biomol Spectrosc ; 216: 328-334, 2019 Jun 05.
Artículo en Inglés | MEDLINE | ID: mdl-30909089

RESUMEN

Considering the excellent photochemical properties of ruthenium(II) complexes, two new ruthenium(II) complexes, RuL1-DNBS and RuL2-DNBS, have been developed as phosphorescence probes for detection of biothiols in 100:1 (v/v) Hepes buffer (20 mM, pH = 7.2)/CH3CN solution. The response rate was highly improved of these two probes toward biothiols because the steric interactions between 1H-imidazo [4, 5-f] [1,10] phenanthroline group and ortho-2, 4-dinitrobenzensulfonate resulted in a relatively rapid thiol-induced SNAr substitution reaction. RuL1-DNBS and RuL2-DNBS were weakly phosphorescent owing to the effectual photoinduced electron transfer from ruthenium(II) luminophore to the sensing group, 2,4-dinitrobenzenesulfonyl. After reacting with biothiols, the 2,4-dinitrobenzenesulfonyl group of RuL1-DNBS and RuL2-DNBS were cleavaged and the RuL1 and RuL2 were obtained. Meanwhile, the phosphorescence were "turn-on". Both of these two probes can detect biothiols sensitively and selectively under physiological conditions with submicromolar detection limits. Furthermore, application of RuL2-DNBS for detecting of intracellular biothiols has been successfully performed in living Glioma cells.


Asunto(s)
Complejos de Coordinación/química , Dinitrobencenos/química , Sustancias Luminiscentes/química , Rutenio/química , Compuestos de Sulfhidrilo/análisis , Línea Celular Tumoral , Glioma/química , Glioma/patología , Humanos , Mediciones Luminiscentes/métodos , Imagen Óptica/métodos , Fenantrolinas/química
20.
Nano Lett ; 19(4): 2731-2738, 2019 04 10.
Artículo en Inglés | MEDLINE | ID: mdl-30919635

RESUMEN

Nitric oxide (NO) induces a multitude of antitumor activities, encompassing the induction of apoptosis, sensitization to chemo-, radio-, or immune-therapy, and inhibition of metastasis, drug resistance, angiogenesis, and hypoxia, thus attracting much attention in the area of cancer intervention. To improve the precise targeting and treatment efficacy of NO, a glutathione (GSH)-sensitive NO donor (1,5-bis[(l-proline-1-yl)diazen-1-ium-1,2-diol- O2-yl]-2,4-dinitrobenzene, BPDB) coordinates with iron ions to form the nanoscale coordination polymer (NCP) via a simple precipitation and then partial ion exchange process. The obtained Fe(II)-BNCP shows desirable solubility, biocompatibility, and circulation stability. Quick NO release triggered by high concentrations of GSH in tumor cells improves the specificity of NO release in situ, thus avoiding side effects in other tissues. Meanwhile, under high concentrations of H2O2 in tumors, Fe2+ ions in BPDB-based NCP, named Fe(II)-BNCP, exert Fenton activity to generate hydroxyl radicals (·OH), which is the main contribution for chemodynamic therapy (CDT). In addition, ·O2- generated by the Haber-Weiss reaction of Fe2+ ions with H2O2 can quickly react with NO to produce peroxynitrite anion (ONOO-) that is more cytotoxic than ·O2- or NO only. This synergistic NO-CDT effect has been proved to retard the tumor growth in Heps xenograft ICR mouse models. This work not only implements a synergistic effect of NO-CDT therapy but also offers a simple and efficient strategy to construct a coordination polymer nanomedicine via rationally designed prodrug molecules such as NO donors.


Asunto(s)
Neoplasias Hepáticas/tratamiento farmacológico , Nanomedicina/métodos , Donantes de Óxido Nítrico/química , Óxido Nítrico/química , Animales , Apoptosis/efectos de los fármacos , Hipoxia de la Célula/efectos de los fármacos , Línea Celular Tumoral , Dinitrobencenos/química , Glutatión/química , Humanos , Peróxido de Hidrógeno/química , Neoplasias Hepáticas/patología , Óxido Nítrico/biosíntesis , Polímeros/administración & dosificación , Polímeros/síntesis química , Polímeros/química , Profármacos/administración & dosificación , Profármacos/síntesis química , Profármacos/química , Ratas
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