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1.
J Nat Prod ; 87(4): 976-983, 2024 04 26.
Artigo em Inglês | MEDLINE | ID: mdl-38438310

RESUMO

Three unique linear oligomeric depsipeptides, designated as cavomycins A-C (1-3), were identified from Streptomyces cavourensis, a gut bacterium associated with the annelid Paraleonnates uschakovi. The structures of these depsipeptides were determined through a combination of spectroscopic methods and chemical derivatization techniques, including methanolysis, the modified Mosher's method, advanced Marfey's methods, and phenylglycine methyl ester derivatization. The unique dipeptidyl residue arrangements in compounds 1-3 indicate that they are not degradation products of valinomycin. Compound 2 and its methylation derivative 2a exhibited antiproliferative activity against PANC-1 pancreatic cancer cells with IC50 values of 1.2 and 1.7 µM, respectively.


Assuntos
Depsipeptídeos , Streptomyces , Streptomyces/química , Depsipeptídeos/farmacologia , Depsipeptídeos/química , Depsipeptídeos/isolamento & purificação , Humanos , Estrutura Molecular , Animais , Ensaios de Seleção de Medicamentos Antitumorais , Antineoplásicos/farmacologia , Antineoplásicos/química , Antineoplásicos/isolamento & purificação
2.
Bioorg Chem ; 128: 106074, 2022 11.
Artigo em Inglês | MEDLINE | ID: mdl-35987188

RESUMO

The imidazo[1,2-a]pyridine-3-carboxyamides (IAPs) are a unique class of compounds endowed with impressive nanomolar in vitro potency against Mycobacterium tuberculosis (Mtb) as exemplified by clinical candidate Telacebec (Q203). These compounds target mycobacterial respiration through inhibition of the QcrB subunit of cytochrome bc1:aa3 super complex resulting in bacteriostatic efficacy in vivo. Our labs have had a long-standing interest in the design and development of IAPs. However, some of these compounds suffer from short in vivo half-lives, requiring multiple daily dosing or the addition of a cytochrome P450 inhibitor for murine efficacy evaluations. Deuteration has been shown to decrease metabolism as the C-D bond is stronger than the CH bond. Herein we describe our efforts on design and synthesis of potent deuterated IAPs and the effect that deuteration has upon metabolism through microsomal stability studies.


Assuntos
Mycobacterium tuberculosis , Tuberculose , Animais , Antituberculosos/química , Humanos , Camundongos , Piridinas/metabolismo , Piridinas/farmacologia , Tuberculose/microbiologia
3.
Antimicrob Agents Chemother ; 65(8): e0028221, 2021 07 16.
Artigo em Inglês | MEDLINE | ID: mdl-34097493

RESUMO

Anti-infective drug discovery is greatly facilitated by the availability of in vitro assays that are more proficient at predicting the preclinical success of screening hits. Tuberculosis (TB) drug discovery is hindered by the relatively slow growth rate of Mycobacterium tuberculosis and the use of whole-cell-based in vitro assays that are inherently time-consuming, and for these reasons, rapid, noninvasive bioluminescence-based assays have been widely used in anti-TB drug discovery and development. In this study, in vitro assays that employ autoluminescent M. tuberculosis were optimized to determine MIC, minimum bactericidal concentration (MBC), time-kill curves, activity against macrophage internalized M. tuberculosis (90% effective concentration [EC90]), and postantibiotic effect (PAE) to provide rapid and dynamic biological information. Standardization of the luminescence-based MIC, MBC, time-kill, EC90, and PAE assays was accomplished by comparing results of established TB drugs and two ClpC1-targeting TB leads, ecumicin and rufomycin, to those obtained from conventional assays and/or to previous studies. Cumulatively, the use of the various streamlined luminescence-based in vitro assays has reduced the time for comprehensive in vitro profiling (MIC, MBC, time-kill, EC90, and PAE) by 2 months. The luminescence-based in vitro MBC and EC90 assays yield time and concentration-dependent kill information that can be used for pharmacokinetic-pharmacodynamic (PK-PD) modeling. The MBC and EC90 time-kill graphs revealed a significantly more rapid bactericidal activity for ecumicin than rufomycin. The PAEs of both ecumicin and rufomycin were comparable to that of the first-line TB drug rifampin. The optimization of several nondestructive, luminescence-based TB assays facilitates the in vitro profiling of TB drug leads in an efficient manner.


Assuntos
Anti-Infecciosos , Mycobacterium tuberculosis , Tuberculose , Antituberculosos/farmacologia , Antituberculosos/uso terapêutico , Humanos , Testes de Sensibilidade Microbiana , Tuberculose/tratamento farmacológico
4.
Gynecol Oncol ; 163(3): 506-510, 2021 12.
Artigo em Inglês | MEDLINE | ID: mdl-34602286

RESUMO

PURPOSE: To investigate the incidence and survival outcomes of primary ovarian sarcoma compared to those of epithelial ovarian cancer. METHODS: Data on primary ovarian sarcoma patients (n = 1361) and epithelial ovarian cancer patients (n = 30,366) between 1999 and 2017 were obtained from the Korea Central Cancer Registry, and their respective age-standardized incidence rate (ASR) and relative survival rate were calculated and compared. RESULTS: Based on the ASR, the incidence of epithelial ovarian cancer was 4.75 per 100,000 women, while that of primary ovarian sarcoma was 0.22 per 100,000 women. The ASR ratio was 21.94 without significant change of ASR during the study period. Primary ovarian sarcoma had a better survival curve compared with epithelial ovarian cancer, though the difference was not statistically significant (5 yr overall survival 64.0% vs. 61.5%; p = 0.6030). In addition, among the pure sarcomas, the fibrosarcoma histologic subtype showed the best overall survival, and that of liposarcomas and stromal cell sarcoma were behind that (5 yr overall survival 85.0%, 76.7%, and 72.7%; p < 0.0001). CONCLUSIONS: The incidence of primary ovarian sarcoma is quite low, with an ASR of 0.22/100,000 during the last 20 years. There were no significant differences between survival rates of primary ovarian sarcoma and epithelial ovarian cancer.


Assuntos
Carcinoma Epitelial do Ovário/epidemiologia , Carcinoma Epitelial do Ovário/terapia , Neoplasias Ovarianas/epidemiologia , Neoplasias Ovarianas/terapia , Sarcoma/epidemiologia , Sarcoma/terapia , Adulto , Idoso , Idoso de 80 Anos ou mais , Carcinoma Epitelial do Ovário/patologia , Feminino , Humanos , Incidência , Pessoa de Meia-Idade , Estadiamento de Neoplasias , Neoplasias Ovarianas/patologia , Sistema de Registros , República da Coreia/epidemiologia , Sarcoma/patologia , Resultado do Tratamento
5.
J Nat Prod ; 84(10): 2644-2663, 2021 10 22.
Artigo em Inglês | MEDLINE | ID: mdl-34628863

RESUMO

Rufomycin and ilamycin are synonymous for the same class of cyclopeptides, currently encompassing 33 structurally characterized isolates and 9 semisynthetic derivatives. Elucidation of new structures prioritized the consolidation of the names and established the structures of four diastereoisomeric rufomycins with a 2-piperidinone, named rufomycins 4-7, including full 1H/13C NMR assignments. The characteristic HSQC cross-peak for the CH-5, the hemiaminal carbon in amino acid #5, allows assignment of the stereocenters C-4 and C-5 within this ring. Semisynthetic derivatives (rufomycinSS 1, 2, and 3) were prepared from a rufomycins 4 and 6 mixture to validate the structural assignments. Based on the X-ray crystal structures of rufomycins 2 and 4, considering the NMR differences of rufomycins 7 vs 4-6 compared to rufomycinSS 1 vs 2 and 3, and taking into account that two major conformers, A and B, occur in both rufomycinSS 2 and 3, structural modeling was pursued. Collectively, this paper discusses the NMR spectroscopic differences of the stereoisomers and their possible 3D conformers and correlates these with the anti-Mycobacterium tuberculosis activity. In addition, a look at the history prioritizes names and numbering schemes for this group of antibiotics and leads to consolidated nomenclature for all currently known members, natural and semisynthetic derivatives, and serves to accommodate future discoveries.


Assuntos
Oligopeptídeos/química , Peptídeos Cíclicos/química , Antituberculosos/química , Espectroscopia de Ressonância Magnética , Testes de Sensibilidade Microbiana , Estrutura Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Terminologia como Assunto
6.
J Nat Prod ; 83(3): 657-667, 2020 03 27.
Artigo em Inglês | MEDLINE | ID: mdl-32031795

RESUMO

This study represents a systematic chemical and biological study of the rufomycin (RUF) class of cyclic heptapeptides, which our anti-TB drug discovery efforts have identified as potentially promising anti-TB agents that newly target the caseinolytic protein C1, ClpC1. Eight new RUF analogues, rufomycins NBZ1-NBZ8 (1-8), as well as five known peptides (9-13) were isolated and characterized from the Streptomyces atratus strain MJM3502. Advanced Marfey's and X-ray crystallographic analysis led to the assignment of the absolute configuration of the RUFs. Several isolates exhibited potent activity against both pathogens M. tuberculosis H37Rv and M. abscessus, paired with favorable selectivity (selectivity index >60), which collectively underscores the promise of the rufomycins as potential anti-TB drug leads.


Assuntos
Antituberculosos/farmacologia , Mycobacterium tuberculosis/efeitos dos fármacos , Oligopeptídeos/farmacologia , Streptomyces/química , Cristalografia por Raios X , Testes de Sensibilidade Microbiana , Estrutura Molecular
7.
Artigo em Inglês | MEDLINE | ID: mdl-30602512

RESUMO

ClpC1 is an emerging new target for the treatment of Mycobacterium tuberculosis infections, and several cyclic peptides (ecumicin, cyclomarin A, and lassomycin) are known to act on this target. This study identified another group of peptides, the rufomycins (RUFs), as bactericidal to M. tuberculosis through the inhibition of ClpC1 and subsequent modulation of protein degradation of intracellular proteins. Rufomycin I (RUFI) was found to be a potent and selective lead compound for both M. tuberculosis (MIC, 0.02 µM) and Mycobacterium abscessus (MIC, 0.4 µM). Spontaneously generated mutants resistant to RUFI involved seven unique single nucleotide polymorphism (SNP) mutations at three distinct codons within the N-terminal domain of clpC1 (V13, H77, and F80). RUFI also significantly decreased the proteolytic capabilities of the ClpC1/P1/P2 complex to degrade casein, while having no significant effect on the ATPase activity of ClpC1. This represents a marked difference from ecumicin, which inhibits ClpC1 proteolysis but stimulates the ATPase activity, thereby providing evidence that although these peptides share ClpC1 as a macromolecular target, their downstream effects are distinct, likely due to differences in binding.


Assuntos
Proteases Dependentes de ATP/antagonistas & inibidores , Antituberculosos/farmacologia , Mycobacterium abscessus/efeitos dos fármacos , Mycobacterium tuberculosis/efeitos dos fármacos , Oligopeptídeos/farmacologia , Proteínas de Bactérias/antagonistas & inibidores , Testes de Sensibilidade Microbiana , Infecções por Mycobacterium não Tuberculosas/tratamento farmacológico , Infecções por Mycobacterium não Tuberculosas/microbiologia , Tuberculose Pulmonar/tratamento farmacológico , Tuberculose Pulmonar/microbiologia
8.
Nanotechnology ; 30(42): 425401, 2019 Oct 18.
Artigo em Inglês | MEDLINE | ID: mdl-31300621

RESUMO

In this work, we demonstrate the synthesis of edge-rich vertical multilayer graphene nanotube arrays and edge density-dependent capacitance in a supercapacitor application. We employ Ni-Au multi-block vertical nanotubes fabricated by anodic aluminum oxide template-assisted electrodeposition as a designer substrate for multilayer graphene growth. This edge generation of graphene relies on the distinct carbon solubility of Au and Ni under chemical vapor deposition. Therefore the graphene edge density is tailorable by controlling the total number of bimetallic interfaces of alternating electrodeposited Ni and Au blocks. In supercapacitor applications, we found that the capacitance heavily correlates to the graphene edge densities. Multilayer graphene nanotubes with 18 bimetallic interfaces exhibit 8.4 times higher capacitance than those without interfaces. This experimental evaluation shows great promise to significantly enhance the supercapacitor capacitance by creating high-density edges on multilayer graphene.

9.
Mar Drugs ; 17(9)2019 Sep 10.
Artigo em Inglês | MEDLINE | ID: mdl-31510079

RESUMO

Three new lavandulylated flavonoids, (2S,2''S)-6-lavandulyl-7,4'-dimethoxy-5,2'-dihydroxylflavanone (1), (2S,2''S)-6-lavandulyl-5,7,2',4'-tetrahydroxylflavanone (2), and (2''S)-5'-lavandulyl-2'-methoxy-2,4,4',6'-tetrahydroxylchalcone (3), along with seven known compounds 4-10 were isolated from culture broth of Streptomyces sp. G248. Their structures were established by spectroscopic data analysis, including 1D and 2D nuclear magnetic resonance (NMR), and high-resolution electrospray ionization mass spectrometry (HR-ESI-MS). The absolute configurations of 1-3 were resolved by comparison of their experimental and calculated electronic circular dichroism spectra. Compounds 1-3 exhibited remarkable antimicrobial activity. Whereas, two known compounds 4 and 5 exhibited inhibitory activity against Mycobacterium tuberculosis H37Rv with minimum inhibitory concentration (MIC) values of 6.0 µg/mL and 11.1 µg/mL, respectively.


Assuntos
Antibióticos Antituberculose/farmacologia , Flavonoides/farmacologia , Poríferos/microbiologia , Streptomyces/química , Animais , Antibióticos Antituberculose/química , Antibióticos Antituberculose/isolamento & purificação , Linhagem Celular Tumoral , Dicroísmo Circular , Flavonoides/química , Flavonoides/isolamento & purificação , Espectroscopia de Ressonância Magnética , Testes de Sensibilidade Microbiana , Estrutura Molecular , Mycobacterium tuberculosis/efeitos dos fármacos , Espectrometria de Massas por Ionização por Electrospray , Vietnã
10.
J Korean Med Sci ; 34(31): e190, 2019 Aug 12.
Artigo em Inglês | MEDLINE | ID: mdl-31392852

RESUMO

BACKGROUND: Although effective care for type 2 diabetes (T2DM) is well known, considerable inadequate care has been still existed. Variations in achievement of the recommended quality indicators inT2DM care among small areas are not well known in Korea. This study examined the quality of care T2DM care and its geographical variations. METHODS: We used the national health insurance database and national health screening database. Seven quality indicators were used to evaluate continuity of care (medication possession ratio), process of care (hemoglobin A1c test, lipid profile, microalbuminuria test, and eye examination), and intermediate outcome (blood pressure control, and low-density lipoprotein control). Crude and age-standardized proportions were calculated for each 252 districts in Korea. RESULTS: All quality indicators failed to achieve the recommended level. Only about 3% and 15% of the patients underwent eye examination and microalbuminuria test, respectively. Other indicators ranged from 48% to 68%. Wide variation in the quality existed among districts and indicators. Eye examination and microalbuminuria test varied the most showing tenfold (0.9%-9.2%) and fourfold (6.3%-28.9%) variation by districts, respectively. There were 32.4 and 42.7 percentage point gap between the best and the worst districts in hemoglobin A1c test and blood pressure control, respectively. CONCLUSION: Considerable proportion of T2DM patients were not adequately managed and quality of care varied substantially district to district. To improve the quality of diabetes care, it is necessary to identify the poor performance areas and establish a well-coordinated care system tailored to the need of the district.


Assuntos
Diabetes Mellitus Tipo 2/epidemiologia , Diabetes Mellitus Tipo 2/terapia , Nível de Saúde , Disparidades em Assistência à Saúde , Cooperação do Paciente , Adulto , Idoso , Idoso de 80 Anos ou mais , Pressão Sanguínea , Continuidade da Assistência ao Paciente , Estudos Transversais , Bases de Dados Factuais , Feminino , Geografia , Hemoglobinas Glicadas/análise , Disparidades nos Níveis de Saúde , Humanos , Seguro Saúde , Lipoproteínas LDL/sangue , Masculino , Programas de Rastreamento , Pessoa de Meia-Idade , Qualidade da Assistência à Saúde , República da Coreia/epidemiologia , População Rural , Resultado do Tratamento , População Urbana
11.
Sensors (Basel) ; 19(8)2019 Apr 20.
Artigo em Inglês | MEDLINE | ID: mdl-31010030

RESUMO

Due to the rapid development of Internet of Things (IoT), IoT platforms that can provide common functions for things are becoming increasingly important. However, access control frameworks in diverse IoT platforms have been developed for individual security goals, designs, and technologies. In particular, current OAuth-based access control frameworks that are widely used in IoT research have not been providing interoperability among IoT platforms even though sharing resources and services is a critical issue for IoT platforms. Therefore, we analyze the main requirements for an IoT access control framework to properly design our framework and propose an interoperable access control framework based on OAuth 2.0 and Role. Our approach describes a new extended authorization grant flow to issue an Interoperable Access Token (IAT) that has a global access scope across IoT platforms using multiple pairs of clients' credentials. With the IAT and proposed framework, we can access client-specific domains in heterogeneous IoT platforms, then valuable resources (e.g., data and services) in the domains can be accessed by validating the roles, which will greatly simplify permission management. Furthermore, IAT supports a simple token management (e.g., token issuance, refreshing, and revocation) by managing only one token for diverse IoT platforms. In addition, we implement our interoperable access control framework on Mobius and FIWARE, which are promising open-source IoT platforms, and test an interoperability scenario to demonstrate our approach with the implementation. Furthermore, the proposed framework is compared with other IoT access control approaches based on the selected requirements in this paper.

12.
J Org Chem ; 83(12): 6664-6672, 2018 06 15.
Artigo em Inglês | MEDLINE | ID: mdl-29792329

RESUMO

Residual complexity (RC) involves the impact of subtle but critical structural and biological features on drug lead validation, including unexplained effects related to unidentified impurities. RC commonly plagues drug discovery efforts due to the inherent imperfections of chromatographic separation methods. The new diketopiperazine, rufomyazine (6), and the previously known antibiotic, rufomycin (7), represent a prototypical case of RC that (almost) resulted in the misassignment of biological activity. The case exemplifies that impurities well below the natural abundance of 13C (1.1%) can be highly relevant and calls for advanced analytical characterization of drug leads with extended molar dynamic ranges of >1:1,000 using qNMR and LC-MS. Isolated from an actinomycete strain, 6 was originally found to be active against Mycobacterium tuberculosis with a minimum inhibitory concentration (MIC) of 2 µg/mL and high selectivity. As a part of lead validation, the dipeptide was synthesized and surprisingly found to be inactive. The initially observed activity was eventually attributed to a very minor contamination (0.24% [m/m]) with a highly active cyclic peptide (MIC ∼ 0.02 µM), subsequently identified as an analogue of 7. This study illustrates the serious implications RC can exert on organic chemistry and drug discovery, and what efforts are vital to improve lead validation and efficiency, especially in NP-related drug discovery programs.


Assuntos
Antituberculosos/química , Antituberculosos/farmacologia , Descoberta de Drogas , Mycobacterium tuberculosis/efeitos dos fármacos , Oligopeptídeos/química , Oligopeptídeos/farmacologia , Espectroscopia de Ressonância Magnética Nuclear de Carbono-13 , Cromatografia Líquida/métodos , Espectrometria de Massas/métodos , Testes de Sensibilidade Microbiana , Espectroscopia de Prótons por Ressonância Magnética
13.
Nanotechnology ; 29(37): 375602, 2018 Sep 14.
Artigo em Inglês | MEDLINE | ID: mdl-29933249

RESUMO

Site-selective synthesis of nanostructures is an important topic in the nanoscience community. Normally, the difference between seeds and deposition atoms in terms of crystallinity triggers the deposition atoms to grow initially at the specific site of nucleation. It is more challenging to control the deposition site of atoms that have the same composition as the seeds because the atoms tend to grow epitaxially, covering the whole surface of the seed nanoparticles. Gold (Au) nano-octahedrons used as seeds in this study possess obvious hierarchical surface energies depending on whether they are at vertices, edges, or terraces. Although vertices of Au nano-octahedrons have the highest surface energy, it remains a challenge to selectively deposit Au atoms at the vertices but not at the edges and faces; this selectivity is required to meet the ever-increasing demands of engineered nanomaterial properties. This work demonstrates an easy and robust method to precisely deposit Au nanoparticles at the vertices of Au nano-octahedrons via wet-chemical seed-mediated growth. The successful synthesis of octahedral Au tip-blobbed nanoparticles (Oh Au TBPs) benefited from the cooperative use of thin silver (Ag) layers at the surface of Au nano-octahedron seeds and iodide ions in the Au growth solution. As-synthesized Au nanostructures (i.e., Au TBPs) gave rise to hybrid optical properties, as evidenced from the UV-vis-NIR extinction spectra, in which a new extinction peak appeared after Au nanoparticles were formed at the vertices of Au nano-octahedrons. A sensitivity evaluation toward dielectric media of a mixture of dimethyl sulfoxide and water suggested that Au TBPs were more optically sensitive compared to the original Au nano-octahedrons. The method demonstrated in this work is promising in the synthesis of advanced Au nanostructures with hybrid optical properties for versatile applications, by engineering the surface energy of vertex-bearing Au nanostructures to trigger site-selective overgrowth of congener Au atoms.

14.
Biomed Chromatogr ; 32(4)2018 Apr.
Artigo em Inglês | MEDLINE | ID: mdl-29164636

RESUMO

We have developed an analytical method for the determination of lincomycin, tylosin A and tylosin B residues in royal jelly using liquid chromatography-triple quadrupole tandem mass spectrometry analysis. For extraction and purification, we employed 1% trifluoroacetic acid and 0.1 m Na2 EDTA solutions along with an Oasis HLB cartridge. The target antibiotics were well separated in a Kinetex EVO C18 reversed-phase analytical column using a combination of 0.1% formate acid in ultrapure water (A) and acetonitrile (B) as the mobile phase. Good linearity was achieved over the tested concentration range (5-50 µg/kg) in matrix-matched standard calibration. The coefficients of determination (R2 ) were 0.9933, 0.9933 and 0.996, for tylosin A, tylosin B and lincomycin, respectively. Fortified royal jelly spiked with three different concentrations of the tested antibiotics (5, 10 and 20 µg/kg) yielded recoveries in the range 80.94-109.26% with relative standard deviations ≤4%. The proposed method was applied to monitor 11 brand of royal jelly collected from domestic markets and an imported brand from New Zealand; all the samples tested negative for lincomycin, tylosin A and tylosin B residues. In conclusion, 1% trifluoroacetic acid and 0.1 m Na2 EDTA aqueous solvents combined with solid-phase extraction could effectively complete the sample preparation process for royal jelly before analysis. The developed approach can be applied for a routine analysis of lincomycin, tylosin A and tylosin B residues in royal jelly.


Assuntos
Resíduos de Drogas , Ácidos Graxos/análise , Ácidos Graxos/química , Lincomicina , Extração em Fase Sólida/métodos , Tilosina , Cromatografia Líquida/métodos , Resíduos de Drogas/análise , Resíduos de Drogas/isolamento & purificação , Limite de Detecção , Lincomicina/análise , Lincomicina/isolamento & purificação , Modelos Lineares , Reprodutibilidade dos Testes , Espectrometria de Massas em Tandem/métodos , Tilosina/análogos & derivados , Tilosina/análise , Tilosina/isolamento & purificação
15.
Angew Chem Int Ed Engl ; 57(7): 1841-1845, 2018 02 12.
Artigo em Inglês | MEDLINE | ID: mdl-29266670

RESUMO

An unprecedented active and dynamic sensing platform based on a LSPR configuration that is modulated by using an external magnetic field is reported. Electrochemically synthesized Au/Fe/Au nanorods exhibited plasmonically active behavior through plasmonic coupling, and the middle ferromagnetic Fe block responded to a magnetic impetus, allowing the nanorods to be modulated. The shear force variation induced by the specific binding events between antigens and antibodies on the nanorod surface is used to enhance the sensitivity of detection of antigens in the plasmonics-based sensor application. As a proof-of-concept, influenza A virus (HA1) was used as a target protein. The limit of detection was enhanced by two orders of magnitude compared to that of traditional LSPR sensing.


Assuntos
Nanotubos/química , Ressonância de Plasmônio de Superfície , Análise de Fourier , Ouro/química , Vírus da Influenza A/metabolismo , Ferro/química , Limite de Detecção , Magnetismo , Proteínas Virais/análise
16.
Nanotechnology ; 28(3): 035604, 2017 Jan 20.
Artigo em Inglês | MEDLINE | ID: mdl-27966470

RESUMO

This work demonstrates that thin-walled platinum nanotubes can be readily synthesized by controlling the interfacial double layer in alumina nanochannels. The gradient distribution of ions in nanochannels enables the creation of Pt nanotubes with walls as thin as 5 nm at the top end when using a solution containing polyvinylpyrrolidone (PVP) and chloroplatinic acid (H2PtCl6) under the influence of an electric potential in nanochannels. The highly efficient formation of thin-walled Pt nanotubes is a result of the concentration gradient of [Formula: see text] and a thick double layer, which was caused by the low concentration of Pt precursors and the enhanced surface charge density induced by protonated PVP steric adsorption. This well-controlled synthesis reveals that the interfacial double layer is a useful tool to tailor the structure of nanomaterials in a nanoscale space, and holds promise in the construction of more complex functional nanostructures.

17.
J Nat Prod ; 80(10): 2630-2643, 2017 10 27.
Artigo em Inglês | MEDLINE | ID: mdl-29035048

RESUMO

This report describes an approach using 1H NMR iterative full-spin analysis (HiFSA) to extract definitive structural information on unknown peptides from 1D 1H NMR data. By comparing the experimental data and HiFSA fingerprint of a known analogue, it is possible to isolate the characteristic 1H subspectrum of the different amino acids and, thus, elucidate the structure of the peptide. To illustrate this methodology, a comprehensive analysis of five new anti-Mycobacterium tuberculosis peptides (2-6), all analogues of ecumicin (1), was carried out. The method was validated by demonstrating congruence of the HiFSA-based structures with all available data, including MS and 2D NMR. The highly reproducible HiFSA fingerprints of the new ∼1600 amu peptides were generated in this process. Besides oligo-peptides, the HiFSA sequencing approach could be extended to all oligomeric compounds consisting of chains of monomers lacking H-H spin-spin coupling across the moieties. HiFSA sequencing is capable of differentiating complex oligomers that exhibit minor structural differences such as shifted hydoxyl or methyl groups. Because it employs the basic and most sensitive 1D 1H NMR experiment, HiFSA sequencing enables the exploration of peptide analogues up to at least 2000 amu, even with basic contemporary spectrometers and when only sub-milligram amounts of isolates are available.


Assuntos
Antituberculosos/isolamento & purificação , Oligopeptídeos/química , Prótons , Antituberculosos/química , Antituberculosos/farmacologia , Estrutura Molecular , Mycobacterium tuberculosis/química , Ressonância Magnética Nuclear Biomolecular , Peptídeos Cíclicos/química , Peptídeos Cíclicos/isolamento & purificação
18.
Environ Res ; 155: 175-181, 2017 05.
Artigo em Inglês | MEDLINE | ID: mdl-28226276

RESUMO

Epidemiologic studies have indicated that albuminuria is associated with mortality from all causes and cardiovascular disease (CVD), with substantial heterogeneity. We evaluated if the associations of urine albumin creatinine ratio (ACR) with all-cause and CVD mortality differed depending on serum concentrations of persistent organic pollutants (POPs), strong lipophilic chemical mixtures with very long half-lives, which are recently linked to many degenerative diseases. Study subjects were participants of the National Health and Nutrition Examination Survey 1999-2004 who were 60 years or older at baseline (n=1215 and 1067 for organochlorine pesticides (OCPs) and other POPs, respectively). They were followed-up through 2011 (mean follow-up periods: 8.1 and 8.0 years for OCPs and other POPs, respectively). The associations between the ACR and all-cause mortality significantly differed by the serum levels of POPs, especially organochlorine pesticides (OCPs; Pinteraction<0.01). Stratified analyses indicated that the associations between ACR and all-cause mortality became stronger as the serum levels of OCPs increased. Among the elderly with the highest tertile of OCPs, the adjusted hazard ratios were 1.0, 1.1, and 2.9 (Ptrend<0.01) across the categories of ACR (<10, 10-<30, and ≥30mg/g); however, ACR was not clearly related to mortality among the elderly with the lowest tertile of OCPs. CVD mortality showed similar interactions, as noted for all-cause mortality (Pinteraction<0.01). The different associations between albuminuria and mortality by the serum OCP levels and the little association among the elderly with low serum OCPs levels suggest that OCPs play an important role in albuminuria-related death risk. However, these findings need to be replicated in other cohort studies.


Assuntos
Albuminúria/sangue , Albuminúria/mortalidade , Doenças Cardiovasculares/sangue , Doenças Cardiovasculares/mortalidade , Poluentes Ambientais/sangue , Hidrocarbonetos Clorados/sangue , Idoso , Feminino , Humanos , Masculino , Pessoa de Meia-Idade , Inquéritos Nutricionais
19.
Biomed Chromatogr ; 31(6)2017 Jun.
Artigo em Inglês | MEDLINE | ID: mdl-27862109

RESUMO

In this study, an analytical method was developed for quantification of residues of the anthelmintic drug phenothiazine (PTZ) in pork muscle using liquid chromatography-tandem mass spectrometry. Muscles were extracted using 0.2% formic acid and 10 mm ammonium formate in acetonitrile, defatted and purified using n-hexane. The drug was well separated on a Waters XBridge™ C18 analytical column using a binary solvent system consisting of 0.2% formic acid and 10 mm ammonium formate in ultrapure water (A) and acetonitrile (B). Good linearity was achieved over a six-point concentration range in matrix-matched calibration with determination coefficient =0.9846. Fortified pork muscle having concentrations equivalent to and double the limit of quantification (1 ng/g) yielded recovery ranges between 100.82 and 104.03% and relative standard deviations <12%. Samples (n = 5) collected from large markets located in Seoul City tested negative for PTZ residue. In conclusion, 0.2% formic acid and ammonium formate in acetonitrile can effectively extract PTZ from pork muscle without solid-phase extraction, a step normally required for cleanup before analysis and the validated method can be used for routine analysis to ensure the quality of animal products.


Assuntos
Cromatografia Líquida/métodos , Produtos da Carne/análise , Músculos/química , Fenotiazinas/análise , Espectrometria de Massas em Tandem/métodos , Animais , Limite de Detecção , Suínos
20.
Biomed Chromatogr ; 31(11)2017 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-28449378

RESUMO

An analytical method was developed for the detection of toldimfos sodium residues in porcine muscle and bovine milk using liquid chromatography-triple quadrupole tandem mass spectrometry (LC-MS/MS) analysis. The drug was extracted from muscle and milk using 10 mm ammonium formate in acetonitrile and then purified using n-hexane. The drug was well separated on a Luna C18 column using a mixture of 10 mm ammonium formate in ultrapure water (A) and acetonitrile (B) as the mobile phase. Good linearity was achieved over the tested concentration range (0.005-0.03 mg/kg) in matrix-matched standard calibration. The determination coefficients (R2 ) were 0.9942 and 0.9898 for muscle and milk, respectively. Fortified porcine muscle and bovine milk contained concentrations equivalent to and twice the limit of quantification (0.005 mg/kg) yielded recoveries in the range of 75.58-89.74% and relative standard deviations of ≤8.87%. Samples collected from large markets located in Seoul, Republic of Korea, tested negative for toldimfos sodium residue. In conclusion, ammonium formate in acetonitrile can effectively extract toldimfos sodium from porcine muscle and bovine milk without solid-phase extraction, which is usually required for cleanup before analysis. This method can be applied for the routine analysis of toldimfos in foods of animal origins.


Assuntos
Cromatografia Líquida/métodos , Resíduos de Drogas/análise , Carne/análise , Leite/química , Ácidos Fosfínicos/análise , Drogas Veterinárias/análise , Animais , Bovinos , Limite de Detecção , Modelos Lineares , Músculos/química , Reprodutibilidade dos Testes , Suínos , Espectrometria de Massas em Tandem/métodos
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