Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 25
Filtrar
1.
Molecules ; 22(3)2017 Mar 06.
Artículo en Inglés | MEDLINE | ID: mdl-28272319

RESUMEN

Radix Astragali is a component of several traditional medicines used for the treatment of type 2 diabetes in China. Radix Astragali is known to contain isoflavones, which inhibit α-glucosidase in the small intestines, and thus lowers the blood glucose levels. In this study, 21 samples obtained from different regions of China were extracted with ethyl acetate, then the IC50-values were determined, and the crude extracts were analyzed by 1H-NMR spectroscopy. A principal component analysis of the 1H-NMR spectra labeled with their IC50-values, that is, bioactivity-labeled 1H-NMR spectra, showed a clear correlation between spectral profiles and the α-glucosidase inhibitory activity. The loading plot and LC-HRMS/NMR of microfractions indicated that previously unknown long chain ferulates could be partly responsible for the observed antidiabetic activity of Radix Astragali. Subsequent preparative scale isolation revealed a compound not previously reported, linoleyl ferulate (1), showing α-glucosidase inhibitory activity (IC50 0.5 mM) at a level comparable to the previously studied isoflavones. A closely related analogue, hexadecyl ferulate (2), did not show significant inhibitory activity, and the double bonds in the alcohol part of 1 seem to be important structural features for the α-glucosidase inhibitory activity. This proof of concept study demonstrates that bioactivity-labeling of the 1H-NMR spectral data of crude extracts allows global and nonselective identification of individual constituents contributing to the crude extract's bioactivity.


Asunto(s)
Medicamentos Herbarios Chinos/química , Medicamentos Herbarios Chinos/farmacología , Inhibidores de Glicósido Hidrolasas/química , Metabolómica , Análisis de Componente Principal , Espectroscopía de Protones por Resonancia Magnética , Astragalus propinquus , Cromatografía Líquida de Alta Presión , Activación Enzimática/efectos de los fármacos , Inhibidores de Glicósido Hidrolasas/farmacología , Concentración 50 Inhibidora , Metabolómica/métodos , alfa-Glucosidasas/química
2.
J Nat Prod ; 78(2): 294-300, 2015 Feb 27.
Artículo en Inglés | MEDLINE | ID: mdl-25679337

RESUMEN

The crude methanol extract of Pueraria lobata was investigated by dual high-resolution α-glucosidase inhibition and radical scavenging profiling combined with hyphenated HPLC-HRMS-SPE-NMR. Direct analysis of the crude extract without preceding purification was facilitated by combining chromatograms from two analytical-scale HPLC separations of 120 and 600 µg on-column, respectively. High-resolution α-glucosidase and radical scavenging profiles were obtained after microfractionation of the eluate in 96-well microplates. This allowed full bioactivity profiling of individual peaks in the HPLC chromatogram of the crude methanol extract. Subsequent HPLC-HRMS-SPE-NMR analysis allowed identification of 21 known compounds in addition to two new compounds, i.e., 3'-methoxydaidzein 8-C-[α-D-apiofuranosyl-(1→6)]-ß-D-glucopyranoside and 6″-O-malonyl-3'-methoxydaidzin, as well as an unstable compound tentatively identified as 3'-de-O-methylpuerariafuran.


Asunto(s)
Glucósidos/aislamiento & purificación , Glucósidos/farmacología , Inhibidores de Glicósido Hidrolasas/aislamiento & purificación , Inhibidores de Glicósido Hidrolasas/farmacología , Isoflavonas/aislamiento & purificación , Isoflavonas/farmacología , Pueraria/química , alfa-Glucosidasas/efectos de los fármacos , Cromatografía Líquida de Alta Presión , Glucósidos/química , Inhibidores de Glicósido Hidrolasas/química , Isoflavonas/química , Estructura Molecular , Resonancia Magnética Nuclear Biomolecular , Extractos Vegetales/química , Extracción en Fase Sólida
3.
Mar Drugs ; 12(4): 2228-44, 2014 Apr 10.
Artículo en Inglés | MEDLINE | ID: mdl-24727393

RESUMEN

Extracts of five halophytes from southern Portugal (Arthrocnemum macrostachyum, Mesembryanthemum edule, Juncus acutus, Plantago coronopus and Halimione portulacoides), were studied for antioxidant, anti-inflammatory and in vitro antitumor properties. The most active extracts towards the 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical were the methanol extracts of M. edule (IC50 = 0.1 mg/mL) and J. acutus (IC50 = 0.4 mg/mL), and the ether extracts of J. acutus (IC50 = 0.2 mg/mL) and A. macrostachyum (IC50 = 0.3 mg/mL). The highest radical scavenging activity (RSA) against the 2,2'-azino-bis (3-ethylbenzothiazoline-6-sulphonic acid) (ABTS) radical was obtained in the ether extract of J. acutus (IC50 = 0.4 mg/mL) and H. portulacoides (IC50 = 0.9 mg/mL). The maximum total phenolic content (TPC) was found in the methanol extract of M. edule (147 mg gallic acid equivalents (GAE)/g) and in the ether extract of J. acutus (94 mg GAE/g). Significant decreases in nitric oxide (NO) production were observed after incubation of macrophages with lipopolysaccharide (LPS) and the chloroform extract of H. portulacoides (IC50 = 109 µg/mL) and the hexane extract of P. coronopus (IC50 = 98.0 µg/mL). High in vitro cytotoxic activity and selectivity was obtained with the ether extract of J. acutus. Juncunol was identified as the active compound and for the first time was shown to display selective in vitro cytotoxicity towards various human cancer cells.


Asunto(s)
Antineoplásicos Fitogénicos/farmacología , Antioxidantes/farmacología , Extractos Vegetales/farmacología , Plantas Tolerantes a la Sal/química , Animales , Antiinflamatorios/química , Antiinflamatorios/aislamiento & purificación , Antiinflamatorios/farmacología , Antineoplásicos Fitogénicos/química , Antineoplásicos Fitogénicos/aislamiento & purificación , Antioxidantes/química , Antioxidantes/aislamiento & purificación , Compuestos de Bifenilo/farmacología , Línea Celular , Línea Celular Tumoral , Depuradores de Radicales Libres/química , Depuradores de Radicales Libres/aislamiento & purificación , Depuradores de Radicales Libres/farmacología , Humanos , Concentración 50 Inhibidora , Lipopolisacáridos/farmacología , Macrófagos/efectos de los fármacos , Macrófagos/metabolismo , Ratones , Óxido Nítrico/metabolismo , Fenoles/química , Fenoles/aislamiento & purificación , Picratos/farmacología , Extractos Vegetales/química , Extractos Vegetales/aislamiento & purificación , Portugal
4.
Anal Chem ; 85(6): 3183-9, 2013 Mar 19.
Artículo en Inglés | MEDLINE | ID: mdl-23432092

RESUMEN

Time-based trapping of chromatographically separated compounds onto solid-phase extraction (SPE) cartridges and subsequent elution to NMR tubes was done to emulate the function of HPLC-NMR for dereplication purposes. Sufficient mass sensitivity was obtained by use of a state-of-the-art HPLC-SPE-NMR system with a cryogenically cooled probe head, designed for 1.7 mm NMR tubes. The resulting (1)H NMR spectra (600 MHz) were evaluated against a database of previously acquired and prepared spectra. The in-house-developed matching algorithm, based on partitioning of the spectra and allowing for changes in the chemical shifts, is described. Two mixtures of natural products were used to test the approach: an extract of Carthamus oxyacantha (wild safflower), containing an array of spiro compounds, and an extract of the endophytic fungus Penicillum namyslowski, containing griseofulvin and analogues. The database matching of the resulting spectra positively identified expected compounds, while the number of false positives was few and easily recognized.


Asunto(s)
Espectroscopía de Resonancia Magnética/métodos , Extracción en Fase Sólida/métodos , Cromatografía Líquida de Alta Presión/métodos , Bases de Datos Farmacéuticas , Griseofulvina/análisis , Extractos Vegetales/análisis
5.
J Pept Sci ; 19(11): 669-75, 2013 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-24019229

RESUMEN

We present the antimicrobial and hemolytic activities of the decapeptide anoplin and 19 analogs thereof tested against methicillin-resistant Staphylococcus aureus ATCC 33591 (MRSA), Escherichia coli (ATCC 25922), Pseudomonas aeruginosa (ATCC 27853), vancomycin-resistant Enterococcus faecium (ATCC 700221) (VRE), and Candida albicans (ATCC 200955). The anoplin analogs contain substitutions in amino acid positions 2, 3, 5, 6, 8, 9, and 10. We use these peptides to study the effect of altering the charge and hydrophobicity of anoplin on activity against red blood cells and microorganisms. We find that increasing the charge and/or hydrophobicity improves antimicrobial activity and increases hemolytic activity. For each strain tested, we identify at least six anoplin analogs with an improved therapeutic index compared with anoplin, the only exception being Enterococcus faecium, against which only few compounds are more specific than anoplin. Both 2Nal(6) and Cha(6) show improved therapeutic index against all strains tested.


Asunto(s)
Antibacterianos/farmacología , Péptidos Catiónicos Antimicrobianos/farmacología , Venenos de Avispas/farmacología , Antibacterianos/síntesis química , Antifúngicos/síntesis química , Antifúngicos/farmacología , Péptidos Catiónicos Antimicrobianos/síntesis química , Candida albicans/efectos de los fármacos , Farmacorresistencia Bacteriana , Enterococcus faecium/efectos de los fármacos , Eritrocitos/efectos de los fármacos , Escherichia coli/efectos de los fármacos , Hemolíticos/síntesis química , Hemolíticos/farmacología , Humanos , Interacciones Hidrofóbicas e Hidrofílicas , Staphylococcus aureus Resistente a Meticilina/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Pseudomonas aeruginosa/efectos de los fármacos , Venenos de Avispas/síntesis química
6.
J Nat Prod ; 75(5): 876-82, 2012 May 25.
Artículo en Inglés | MEDLINE | ID: mdl-22515483

RESUMEN

Solid phase extraction (SPE) was introduced as a crucial step in the HPLC-SPE-NMR technique to enable online analyte enrichment from which proton-detected NMR experiments on submicrogram amounts from complex mixtures were possible. However, the significance of direct-detected (13)C NMR experiments is indubitable in simplifying structural elucidations. In the current study, we demonstrated direct (13)C NMR detection of triterpenoids from a Ganoderma lucidum extract in hyphenation mode. The combined advantage of a cryogenically cooled probe, miniaturization, and multiple trapping enabled the first reported application of HPLC-SPE-NMR analysis using direct-detected (13)C NMR spectra. HPLC column loading, accumulative SPE trappings, and the effect of different elution solvents were evaluated and optimized. A column loading of approximately 600 µg of a prefractionated triterpenoid mixture, six trappings, and an acquisition time of 13 h resulted in spectra with adequate signal-to-noise ratios to detect all C-13 signals.


Asunto(s)
Resonancia Magnética Nuclear Biomolecular/métodos , Reishi/química , Extracción en Fase Sólida/métodos , Triterpenos/análisis , Cromatografía Líquida de Alta Presión/métodos , Estructura Molecular , Esporas Fúngicas/química , Triterpenos/química , Triterpenos/aislamiento & purificación
7.
Planta Med ; 78(17): 1885-90, 2012 Nov.
Artículo en Inglés | MEDLINE | ID: mdl-23059630

RESUMEN

A museum collection of Cinchonae cortex samples (n = 117), from the period 1850-1950, was extracted with a mixture of chloroform-d1, methanol-d4, water-d2, and perchloric acid in the ratios 5 : 5 : 1 : 1. The extracts were directly analyzed using 1H NMR spectroscopy (600 MHz) and the spectra evaluated using principal component analysis (PCA) and total statistical correlation spectroscopy (STOCSY). A new method called STOCSY-CA, where CA stands for component analysis, is described, and an analysis using this method is presented. It was found that the samples had a rather homogenous content of the well-known cinchona alkaloids quinine, cinchonine, and cinchonidine without any apparent clustering. Signals from analogues were detected but not in substantial amounts. The main variation was related to the absolute amounts of extracted alkaloids, which was attributed to the evolution of the Cinchona tree cultivation during the period in which the samples were collected.


Asunto(s)
Alcaloides de Cinchona/aislamiento & purificación , Cinchona/química , Cinchona/genética , Dermatoglifia del ADN , Evolución Molecular , Corteza de la Planta/química , Historia del Siglo XIX , Historia del Siglo XX , Espectroscopía de Resonancia Magnética , Museos/historia , Factores de Tiempo
8.
Anal Chem ; 83(21): 8278-85, 2011 Nov 01.
Artículo en Inglés | MEDLINE | ID: mdl-21950244

RESUMEN

Metabolic profiling of natural products is used to map correlated concentration variances of known and unknown secondary metabolites in extracts. NMR-spectroscopy is in this respect regarded as a convenient and reproducible technique with the ability to detect a wide range of small organic compounds. Two-dimensional J-resolved NMR-spectra are used in this context to resolve overlapping signals by separating the effect of J-coupling from the effect of chemical shifts. Often one-dimensional projections of these data are used as input for standard multivariate statistical methods, and only the intensity variances along the chemical shift axis are taken into account. Here, we describe the use of parallel factor analysis (PARAFAC) as a tool to preprocess a set of two-dimensional J-resolved spectra with the aim of keeping the J-coupling information intact. PARAFAC is a mathematical decomposition method that fits three-way experimental data to a model whose parameters in this case reflect concentrations and individual component spectra along the chemical shift axis and corresponding profiles along the J-coupling axis. A set of saffron samples, directly extracted with methanol-d(4), were used as a model system to evaluate the feasibility and merits of the method. To successfully use PARAFAC, the two-dimensional spectra (n = 96) had to be aligned and processed in narrow windows (0.04 ppm wide) along the chemical shift axis. Selection of windows and number of components for each PARAFAC-model was done automatically by evaluating amount of explained variance and core consistency values. Score plots showing the distribution of objects in relation to each other, and loading plots in the form of two-dimensional pseudospectra with the same appearance as the original J-resolved spectra but with positive and negative contributions are presented. Loadings are interpreted not only in terms of signals with different chemical shifts but also the associated J-coupling profiles.


Asunto(s)
Crocus/química , Análisis Factorial , Espectroscopía de Resonancia Magnética , Metaboloma
9.
J Nat Prod ; 74(11): 2454-61, 2011 Nov 28.
Artículo en Inglés | MEDLINE | ID: mdl-22060189

RESUMEN

An extract of Carthamus oxyacantha (wild safflower) was investigated using two approaches: a traditional, nontarget fractionation by VLC and HPLC, and the hyphenated technique HPLC-PDA-HRMS-SPE-NMR followed by targeted isolation of selected constituents for inclusion in a screening library of pure natural products. While the nontarget fractionation involved considerable time spent on pursuing fractions containing well-known or undesired compounds, the hyphenated analysis was considerably faster and required less solvent and other consumables. The results were used to design and execute an optimized, HPLC-HRMS-guided, targeted isolation scheme aiming exclusively at a series of identified spiro compounds. Thus, HPLC-PDA-HRMS-SPE-NMR is a dereplication technique of choice, allowing economical acquisition of comprehensive data about compounds in crude extracts, which can be used for rational, prospective decisions about further isolation efforts. A total of 15 compounds were identified in the extract. Six spiro compounds, of which four have not previously been characterized, and tracheloside (a lignin glucoside) are presented with assigned 1H and 13C chemical shifts.


Asunto(s)
4-Butirolactona/análogos & derivados , Productos Biológicos/aislamiento & purificación , Carthamus/química , Glucósidos/aislamiento & purificación , Espectroscopía de Resonancia Magnética/métodos , Plantas Medicinales/química , Compuestos de Espiro/aislamiento & purificación , 4-Butirolactona/química , 4-Butirolactona/aislamiento & purificación , Productos Biológicos/química , Cromatografía Líquida de Alta Presión/métodos , Glucósidos/química , Irán , Estructura Molecular , Compuestos de Espiro/química
10.
Phytochem Anal ; 22(2): 158-65, 2011.
Artículo en Inglés | MEDLINE | ID: mdl-20848394

RESUMEN

INTRODUCTION: Rhodiola rosea is a broadly used medicinal plant with largely unexplored natural variability in secondary metabolite levels. OBJECTIVE: The aim of this work was to develop a non-target procedure for ¹H NMR spectroscopic fingerprinting of rhizome extracts for pattern recognition analysis and identification of secondary metabolites responsible for differences in sample composition. To achieve this, plants from three different geographic areas (Swiss Alps, Finland, and Altai region in Siberia) were investigated. RESULTS: A sample preparation procedure was developed in order to remove polymeric polyphenols as the ¹H NMR analysis of low-molecular-weight metabolites was hampered by the presence of tannins. Principal component analysis disclosed tight clustering of samples according to population. PCA models based on the aromatic region of the spectra showed that the first two components reflected changes in the content of salidroside and rosavin, respectively, the rosavin content being negatively correlated to that of rhodiocyanoside A and minor aromatics. Score plots and non-parametric variance tests demonstrated population-dependent changes according to harvest time. Data consistency was assessed using score plots and box-and-whisker graphs. In addition, a procedure for presenting loadings of PCA models based on bucketed data as high-resolution plots, which are reminiscent of real ¹H NMR spectra and help to identify latent biomarkers, is presented. CONCLUSION: This study demonstrated the usefulness of the established procedure for multivariate non-target ¹H NMR metabolic profiling of Rhodiola rosea.


Asunto(s)
Espectroscopía de Resonancia Magnética/métodos , Metaboloma , Metabolómica/métodos , Extractos Vegetales/química , Rhodiola/química , Disacáridos/química , Finlandia , Glucósidos/química , Análisis Multivariante , Fenoles/química , Plantas Medicinales/química , Análisis de Componente Principal , Rizoma/química , Siberia , Suiza , Factores de Tiempo
11.
J Ethnopharmacol ; 242: 112061, 2019 Oct 05.
Artículo en Inglés | MEDLINE | ID: mdl-31283956

RESUMEN

ETHNOPHARMACOLOGICAL RELEVANCE: Berries of Sorbus species have been used to treat type 2 diabetes in many regions in Europe. AIMS OF THE STUDY: To investigate the inhibitory activity of berry extract of Sorbus on the digestive enzymes α-amylase and α-glucosidase, two important targets for management of blood glucose for type 2 diabetics. Furthermore, to test the anti-hyperglycaemic potential of S. norvegica berry extract in vivo. MATERIALS AND METHODS: 70% acetone berry extracts of 16 Sorbus species were tested in vitro for inhibition of α-amylase and α-glucosidase. Single berry extracts were analysed by 1H-NMR spectroscopy and principal component analysis to evaluate the chemical profiles of the extracts. The anti-hyperglycaemic effect was evaluated in an oral starch tolerance test in STZ-treated C57BL/6 mice. RESULTS: The lowest IC50 values against α-amylase and α-glucosidase were obtained with the Sorbus species belonging to the subspecies Aria, which have simple leaves compared to pinnately compound leaves of the other Sorbus species. Species belonging to subspecies Aria grouped together and away from the other Sorbus species in the score plot, indicating a difference in chemistry. Both the carbohydrate- and polyphenol-fraction contributed to the enzyme inhibition. Extract of the most active species, S. norvegica, had anti-hyperglycaemic activity, at a level 36 times lower than clinically used acarbose, corresponding to a needed daily dose of 900 mg extract. CONCLUSIONS: Sorbus species of subspecies Aria have the potential to be used for management of type 2 diabetes.


Asunto(s)
Diabetes Mellitus Experimental/tratamiento farmacológico , Diabetes Mellitus Tipo 2/tratamiento farmacológico , Hipoglucemiantes/uso terapéutico , Extractos Vegetales/uso terapéutico , Sorbus , Animales , Frutas , Hipoglucemiantes/química , Masculino , Metabolómica , Ratones Endogámicos C57BL , Extractos Vegetales/química , Espectroscopía de Protones por Resonancia Magnética , alfa-Amilasas/antagonistas & inhibidores , alfa-Amilasas/química , alfa-Glucosidasas/química
12.
Anal Chem ; 80(9): 3365-71, 2008 May 01.
Artículo en Inglés | MEDLINE | ID: mdl-18363385

RESUMEN

Metabolite profiling relies on optimal precision of the acquired data, which requires, among others, a high signal-to-noise ratio (S/N). In addition, increased S/N will increase the likelihood of identification of new biomarkers. Here we introduce, for the first time in metabolite profiling studies by 1H NMR, an approach to enhance the precision of multivariate regression models by use of the FLIPSY (flip angle adjustable one-dimensional NOESY) pulse sequence, augmented by a homospoil pulse after the presaturation period to provide superior baseline quality. Unlike NOESYPRESAT, the standard one-dimensional (1D) sequence generally used in metabonomic studies, FLIPSY incorporates a variable flip angle, allowing use of the Ernst angle for excitation and thus optimization of S/N ratios according to spin lattice relaxation times (T1) of individual resonances. T1 values of metabolites present in human urine were determined by inversion-recovery experiments and subsequently used in calculations of optimal experimental conditions. Comparison of human urine analysis by the FLIPSY and NOESYPRESAT demonstrated an increase of S/N ratio in the former case that amounts to approximately 7% when measured for the hippurate doublet at delta 7.84. An orthogonal projection to latent structures discriminant analysis (O-PLS-DA) model exhibited superior discrimination between controls and simulated phenylketonuria urines when using data generated by the FLIPSY as compared to NOESYPRESAT.


Asunto(s)
Resonancia Magnética Nuclear Biomolecular/métodos , Fenilalanina/orina , Fenilcetonurias/orina , Orina/química , Interpretación Estadística de Datos , Humanos , Modelos Teóricos , Protones
13.
Artículo en Inglés | MEDLINE | ID: mdl-28326125

RESUMEN

The present study was carried out to investigate the wound healing potentials of 17 medicinal plants historically used in Ghana for wound healing. Warm and cold water extracts were prepared from the 17 dried plant species and tested in vitro in the scratch assay with NIH 3T3 fibroblasts from mice. The wound healing scratch assay was used to evaluate the effect of the plants on cell proliferation and/or migration in vitro, as a test for potential wound healing properties. After 21 hours of incubation increased proliferation and/or migration of fibroblasts in the scratch assay was obtained for 5 out of the 17 plant species. HPLC separation of the most active plant extract, which was a warm water extract of Philenoptera cyanescens, revealed the wound healing activity to be attributed to rutin and a triglycoside of quercetin. The present study suggests that Allophylus spicatus, Philenoptera cyanescens, Melanthera scandens, Ocimum gratissimum, and Jasminum dichotomum have wound healing activity in vitro.

14.
Carbohydr Res ; 341(4): 550-6, 2006 Mar 20.
Artículo en Inglés | MEDLINE | ID: mdl-16406276

RESUMEN

It is demonstrated that the H2BC NMR pulse sequence (J. Am. Chem. Soc.2005, 127, 6154, Magn. Reson. Chem.2005, 43, 971-974) offers unambiguous assignments and significant simplification of NMR spectra of large and complex carbohydrates compared to other techniques for the establishment of correlations over more than one bond. H2BC almost exclusively correlates protons and proton-bearing carbon spins separated by two covalent bonds and is independent of occasionally vanishing (2)J(CH) coupling constants, which alleviates the problem of missing two-bond correlations in HMBC spectra. H2BC also solves the problem of distinguishing two- and three-bond correlations in HSQC-TOCSY or HMBC. It is a further asset of H2BC that the experiment is significantly shorter than HMBC and HSQC-TOCSY, and hence less sensitive to transverse relaxation. The H2BC experiment is demonstrated on an approximately 30-residue oligosaccharide from Francisella victoria.


Asunto(s)
Carbohidratos/química , Espectroscopía de Resonancia Magnética/métodos , Polisacáridos Bacterianos/química , Isótopos de Carbono/química , Francisella/química , Hidrógeno/química , Oligosacáridos/química
15.
PLoS One ; 11(2): e0149148, 2016.
Artículo en Inglés | MEDLINE | ID: mdl-26882071

RESUMEN

Protein fibrillation is the pathological hallmark of several neurodegenerative diseases and also complicates the manufacturing and use of protein drugs. As a case study, the inhibitory activity of the natural compound aloin against insulin fibrillation was investigated. Based on Thioflavin T assays, high-performance liquid chromatography and transmission electron microscopy it was found that a degradation product of aloin, formed over weeks of storage, was able to significantly inhibit insulin fibrillation. The activity of the stored aloin was significantly reduced in the presence of small amounts of sodium azide or ascorbic acid, suggesting the active compound to be an oxidation product. A high-performance liquid chromatography method and a liquid chromatography-mass spectrometry method were developed to investigate the degradation products in the aged aloin solution. We found that the major compounds in the solution were aloin A and aloin B. In addition, 10-hydroxy aloin and elgonica dimers were detected in smaller amounts. The identified compounds were isolated and tested for activity by means of Thioflavin T assays, but no activity was observed. Thus, the actual fibrillation inhibitor is an as yet unidentified and potentially metastable degradation product of aloin. These results suggest that degradation products, and in particular oxidation products, are to be considered thoroughly when natural products are investigated for activity against protein fibrillation.


Asunto(s)
Emodina/análogos & derivados , Insulina/química , Antraquinonas/química , Benzotiazoles , Productos Biológicos , Química Farmacéutica , Cromatografía Líquida de Alta Presión , Emodina/química , Excipientes/química , Colorantes Fluorescentes/química , Glucósidos/química , Microscopía Electrónica de Transmisión , Oxidación-Reducción , Estabilidad Proteica , Proteolisis , Soluciones , Espectrometría de Fluorescencia , Tiazoles/química
16.
Eur J Med Chem ; 102: 574-81, 2015 Sep 18.
Artículo en Inglés | MEDLINE | ID: mdl-26318064

RESUMEN

Although cyclic peptide structures are usually investigated as highly constrained scaffolds, cyclic antimicrobial peptides of natural origin often feature flexible residues. Hereby we report our findings concerning a structure-activity study conducted on a model sequence by replacing a glycine residue with a variety of flexible residues (i.e. ω-amino and α,ω-diamino acids). The resulting library has been tested for antimicrobial activity against a wide range of clinically relevant pathogens as well as for toxicity to red blood cells. Circular dichroism and molecular modelling have been used to study changes in conformation. Increments as high as 16-fold in antimicrobial activity (as effective as lipidation) and >2-fold in haemolytic EC50 values were observed. Interestingly, secondary structures can be stabilized by increasing, rather than decreasing, ring flexibility.


Asunto(s)
Aminoácidos/química , Antibacterianos/farmacología , Antifúngicos/farmacología , Glicina/química , Péptidos Cíclicos/farmacología , Tensoactivos/farmacología , Antibacterianos/química , Antifúngicos/química , Bacterias/efectos de los fármacos , Relación Dosis-Respuesta a Droga , Hongos/efectos de los fármacos , Hemólisis/efectos de los fármacos , Pruebas de Sensibilidad Microbiana , Estructura Molecular , Péptidos Cíclicos/química , Relación Estructura-Actividad , Tensoactivos/química
17.
J Chromatogr A ; 1408: 125-32, 2015 Aug 21.
Artículo en Inglés | MEDLINE | ID: mdl-26187760

RESUMEN

In this work, development of a new microplate-based high-resolution profiling assay using recombinant human aldose reductase is presented. Used together with high-resolution radical scavenging and high-resolution α-glucosidase assays, it provided the first report of a triple aldose reductase/α-glucosidase/radical scavenging high-resolution inhibition profile - allowing proof of concept with Radix Scutellariae crude extract as a polypharmacological herbal drug. The triple bioactivity high-resolution profiles were used to pinpoint bioactive compounds, and subsequent structure elucidation was performed with hyphenated high-performance liquid chromatography-high-resolution mass spectrometry-solid-phase extraction-nuclear magnetic resonance spectroscopy. The only α-glucosidase inhibitor was baicalein, whereas main aldose reductase inhibitors in the crude extract were baicalein and skullcapflavone II, and main radical scavengers were ganhuangemin, viscidulin III, baicalin, oroxylin A 7-O-glucuronide, wogonoside, baicalein, wogonin, and skullcapflavone II.


Asunto(s)
Aldehído Reductasa/metabolismo , Depuradores de Radicales Libres/análisis , Hipoglucemiantes/análisis , Scutellaria baicalensis/química , alfa-Glucosidasas/metabolismo , Cromatografía Líquida de Alta Presión , Inhibidores de Glicósido Hidrolasas/análisis , Humanos , Espectroscopía de Resonancia Magnética/métodos , Extractos Vegetales/análisis , Proteínas Recombinantes/metabolismo , Extracción en Fase Sólida
18.
Food Chem ; 161: 192-8, 2014 Oct 15.
Artículo en Inglés | MEDLINE | ID: mdl-24837940

RESUMEN

Bulbs and leaves of 35 Allium species and cultivars bought or collected in 2010-2012 were investigated with multivariate data analysis, high-resolution α-glucosidase inhibition assays and HPLC-HRMS-SPE-NMR with the aim of exploring the potential of Allium as a future functional food for management of type 2 diabetes. It was found that 30 out of 106 crude extracts showed more than 80% inhibition of the α-glucosidase enzyme at a concentration of 40mg/mL (dry sample) or 0.4g/mL (fresh sample). High-resolution α-glucosidase biochromatograms of these extracts allowed fast identification of three analytes with α-glucosidase inhibitory activity, and subsequent HPLC-HRMS-SPE-NMR experiments allowed identification of these as N-p-coumaroyloctopamine, N-p-coumaroyltyramine, and quercetin. The distribution of these three compounds was mapped for all samples by HPLC-ESI-HRMS. Unsupervised principal component analysis of samples from 2012 indicated that a major difference between fresh material and dried material is the increased amount of quercetin, a known α-glucosidase inhibitor.


Asunto(s)
Allium/química , Cromatografía Líquida de Alta Presión/métodos , Espectroscopía de Resonancia Magnética/métodos , Inhibidores de Glicósido Hidrolasas , Análisis Multivariante , Análisis de Componente Principal
19.
Phytochemistry ; 93: 79-87, 2013 Sep.
Artículo en Inglés | MEDLINE | ID: mdl-23642457

RESUMEN

INTRODUCTION: The succulent leaf mesophyll in Aloe species supports a burgeoning natural products industry, particularly in Africa. Comparative data necessary to prioritise species with economic potential have been lacking. OBJECTIVE: To survey leaf mesophyll monosaccharide composition in the genus Aloe using a predictive phylogenetic approach. METHODOLOGY: Monosaccharide composition was assessed in 31 species, representing the morphological and taxonomic diversity of Aloe sensu stricto. Leaf mesophyll polysaccharides were partially hydrolysed in a trifluoroacetic acid (TFA)-SilA assay. Oximes and trimethylsilyl ether products were detected by GC-MS. Constituent monosaccharides accounting for the greatest variation among species were identified by principal component analysis. Two plant DNA barcoding regions were sequenced in 28 of the sampled species and the resulting maximum likelihood tree was used to evaluate phylogenetic signal in monosaccharide composition throughout the genus. RESULTS: Nineteen peaks (Rt=16.76-23.67 min) were identified in the GC-MS spectra. All samples were dominated by one constituent; glucose was the major monosaccharide in 19 species, mannose in eight species, and xylose in one species (Aloidendron pillansii). Three monosaccharides therefore account for 90% of the variation in leaf mesophyll in Aloe. Species which do not share this typical monosaccharide profile appear to group outside the core Aloe clade in the phylogeny. CONCLUSION: Preliminary findings suggest that leaf mesophyll monosaccharide composition is conservative in Aloe. Characterisation of within-species variation and quantitative differences between species will be necessary to authenticate leaf mesophyll products, whereas unusual monosaccharide profiles could be diagnostic in some species. The common glucose-mannose-xylose profile identified in commercially important species is shared by many other Aloe species.


Asunto(s)
Aloe/química , Monosacáridos/análisis , Hojas de la Planta/química , Cromatografía de Gases y Espectrometría de Masas , Análisis Multivariante , Filogenia
20.
J Chromatogr A ; 1302: 34-9, 2013 Aug 09.
Artículo en Inglés | MEDLINE | ID: mdl-23827469

RESUMEN

The high-resolution radical scavenging profile of an extract of the endophytic fungus Penicillium namyslowskii was used to target analysis by high-performance liquid chromatography-high-resolution mass spectrometry-solid-phase extraction-nuclear magnetic resonance spectroscopy, i.e., HPLC-HRMS-SPE-NMR, for identification of anti-oxidative secondary metabolites. This revealed the two chromatographic peaks with the highest relative response in the radical scavenging profile to be griseophenone C and peniprequinolone. The HPLC-HRMS-SPE-NMR analysis was performed in the tube-transfer mode using a cryogenically cooled NMR probe designed for 1.7mm NMR tubes. To further explore the potential of the above HPLC-HRMS-SPE-NMR platform for analysis of endophytic extracts, six peaks displaying no radical scavenging activity were also analyzed. This allowed unambiguous identification of six metabolites, i.e., dechlorogriseofulvin, dechlorodehydrogriseofulvin, griseofulvin, dehydrogriseofulvin, mevastatin acid, and mevastatin. The high mass sensitivity of the 1.7mm cryogenically cooled NMR probe allowed for the first time acquisition of direct detected (13)C NMR spectra of fungal metabolites, i.e., dechlorogriseofulvin and griseofulvin, directly from crude extract via HPLC-HRMS-SPE-NMR. Dechlorodehydrogriseofulvin was reported for the first time from nature.


Asunto(s)
Cromatografía Líquida de Alta Presión/métodos , Espectroscopía de Resonancia Magnética/métodos , Penicillium/metabolismo , Extracción en Fase Sólida/métodos
SELECCIÓN DE REFERENCIAS
DETALLE DE LA BÚSQUEDA