Time filter

Source Type

Llanos G.G.,Instituto Universitario Of Bio Organica Antonio Gonzalez | Araujo L.M.,University of La Laguna | Jimenez I.A.,Instituto Universitario Of Bio Organica Antonio Gonzalez | Moujir L.M.,University of La Laguna | And 2 more authors.
Steroids | Year: 2010

Seven new withanolides (1-7), along with three known ones (8-10), were isolated from the leaves of Withania aristata. Their structures were elucidated on the basis of spectroscopic analysis, including 2D NMR experiments and spectrometric techniques, and the absolute configuration of 1 and 2 was established by CD analysis. In the search for new cytotoxic compounds from Withania species, the isolated compounds 1-9, along with two derivatives, were assayed for their cytotoxicity against HeLa, MCF-7 and A-549 human tumor cell lines. Derivative (4S,20R,22R)-27-acetoxy-4-p-bromobenzoyloxy-1-oxo-witha-2,5, 16,24-tetraenolide (13) showed cytotoxicity against all the cell lines assayed with IC50 values ranging from 2.8 to 3.6 μM, and (4S,20R,22R)-4,27-diacetoxy-4-hydroxy-1-oxo-witha-2,5,16,24-tetraenolide (12) exhibited an IC50 value of 5.4 μM on the MCF-7 cell line. © 2010 Elsevier Inc.


Diaz J.G.,Instituto Universitario Of Bio Organica Antonio Gonzalez | De Paz P.P.,University of La Laguna | Herz W.,Florida State University
Phytochemistry Letters | Year: 2010

The water soluble portion of the aerial parts of Hypericum canariense L. yielded after acetylation the 5,7,3′4′-tetra- and 7,3′4′-triacetates of a new flavonoid 5,7,3′,4′- tetrahydroxy-3-O-β-d-(methyl 2,3,4-triacetoxypyranuronyl)-quercetin, the 3′-acetate of a new flavonoid 3′-hydroxy-5,7,4′-trimethoxy-3- O-β-d-(methyl 2,3,4-triacetoxypyranuronyl)-quercetin, the 3′-acetate and the 3′5′-diacetate of the new flavonoid 5,3′dihydroxy-7, 4′-dimethoxy-3-β-d-(methyl 2,3,4-triacetoxypyranuronyl)-quercetin, the xanthone derivative mangiferin 2′,3′,4′,6′- tetraacetate and the latter's new 1,3,6,7′-tetramethoxy, 1,3,6-trimethoxy-4-acetoxy and 1,7-diacetoxy-3,6-dimethoxy analogs. © 2010 Phytochemical Society of Europe.


Feher-Voelger A.,CSIC - Institute of Natural Products and Agrobiology | Borges-Gonzalez J.,CSIC - Institute of Natural Products and Agrobiology | Carrillo R.,CSIC - Institute of Natural Products and Agrobiology | Morales E.Q.,CSIC - Institute of Natural Products and Agrobiology | And 3 more authors.
Chemistry - A European Journal | Year: 2014

New pyranoid ε-sugar amino acids were designed as building blocks, in which the carboxylic acid and the amine groups were placed in positions C2 and C3 with respect to the tetrahydropyran oxygen atom. By using standard solution-phase coupling procedures, cyclic homooligomers containing pyranoid ε-sugar amino acids were synthesized. Conformation analysis was performed by using NMR spectroscopic experiments, FTIR spectroscopic studies, X-ray analysis, and a theoretical conformation search. These studies reveal that the presence of a methoxy group in the position C4 of the pyran ring produces an important structural change in the cyclodipeptides. When the methoxy groups are present, the structure collapses through interresidue hydrogen bonds between the oxygen atoms of the pyran ring and the amide protons. However, when the cyclodipeptide lacks the methoxy groups, a U-shape structure is adopted, in which there is a hydrophilic concave face with four oxygen atoms and two amide protons directed toward the center of the cavity. Additionally, we found important evidence of the key role played by weak electrostatic interactions, such as the five-membered hydrogen-bonded pseudocycles (C5) between the amide protons and the ether oxygen atoms, in the conformation equilibrium of the macrocycles and in the cyclization step of the cyclic tetrapeptides. To fold or not to fold: ε-Sugar amino acids (ε-SAAs) have proven to be privileged scaffolds for the synthesis of conformationally modulated cyclic peptides. An appendix on the sugar moiety helps to modulate the conformation equilibrium between the folded and unfolded structures by modification of the internal network of noncovalent interactions (see figure). © 2014 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Sistiaga A.,University of La Laguna | Sistiaga A.,Massachusetts Institute of Technology | Sistiaga A.,Instituto Universitario Of Bio Organica Antonio Gonzalez | Mallol C.,University of La Laguna | And 3 more authors.
PLoS ONE | Year: 2014

Neanderthal dietary reconstructions have, to date, been based on indirect evidence and may underestimate the significance of plants as a food source. While zooarchaeological and stable isotope data have conveyed an image of Neanderthals as largely carnivorous, studies on dental calculus and scattered palaeobotanical evidence suggest some degree of contribution of plants to their diet. However, both views remain plausible and there is no categorical indication of an omnivorous diet. Here we present direct evidence of Neanderthal diet using faecal biomarkers, a valuable analytical tool for identifying dietary provenance. Our gas chromatography-mass spectrometry results from El Salt (Spain), a Middle Palaeolithic site dating to ca. 50,000 yr. BP, represents the oldest positive identification of human faecal matter. We show that Neanderthals, like anatomically modern humans, have a high rate of conversion of cholesterol to coprostanol related to the presence of required bacteria in their guts. Analysis of five sediment samples from different occupation floors suggests that Neanderthals predominantly consumed meat, as indicated by high coprostanol proportions, but also had significant plant intake, as shown by the presence of 5β-stigmastanol. This study highlights the applicability of the biomarker approach in Pleistocene contexts as a provider of direct palaeodietary information and supports the opportunity for further research into cholesterol metabolism throughout human evolution. © 2014 Sistiaga et al.


Diaz J.G.,Instituto Universitario Of Bio Organica Antonio Gonzalez | Herz W.,Florida State University
Phytochemistry | Year: 2010

An ethanol extract of the aerial parts of Delphinium gracile DC. yielded five flavonol glycosides quercetin-3-O-{[β-d-xylopyranosyl (1 → 3)-4-O-(E-p-caffeoyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranosyl (1 → 2)]}-β-d-glucopyranoside (1), quercetin-3-O-{[β-d-xylopyranosyl (1 → 3)-4-O-(E-p-coumaroyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranosyl (1 → 2)]}-β-d-glucopyranoside (2), quercetin-3-O-{[β-d-xylopyranosyl (1 → 3)-4-O-(Z-p-coumaroyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranosyl (1 → 2)]}-β-d-glucopyranoside (3), kaempferol-3-O-{[β-d-glucopyranosyl (1 → 3)-4-O-(E-p-coumaroyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranoside-7-O-(4-O-acetyl)-α-l-rhamnopyranoside (4) kaempferol-3-O-{[β-d-glucopyranosyl (1 → 3)-4-O-(E-p-coumaroyl)-α-l-rhamnopyranosyl (1 → 6)][β-d-glucopyranoside-7-O-(4-O-acetyl)-α-l-rhamnopyranoside (5) in addition to 4-(β-d-glucopyranosyloxy)-6-methyl-2H-pyran-2-one (6) and rutin. Structures were elucidated by spectroscopic methods. © 2009 Elsevier Ltd. All rights reserved.


Berkov S.,University of Barcelona | Berkov S.,Agrobioinstitute Dragan Tzankov Blvd. | Viladomat F.,University of Barcelona | Codina C.,University of Barcelona | And 3 more authors.
Journal of Mass Spectrometry | Year: 2012

Galanthamine-type alkaloids produced by plants of the Amaryllidaceae family are potent acetylcholinesterase inhibitors. One of them, galanthamine, has been marketed as a hydrobromide salt for the treatment of Alzheimer's disease. In the present work, gas chromatography with electron impact mass spectrometry (GC-EIMS) fragmentation of 12 reference compounds isolated from various amaryllidaceous plants and identified by spectroscopic methods (1D and 2D nuclear magnetic resonance, circular dichroism, high-resolution MS (HRMS) and EIMS) was studied by tandem mass spectrometry (GC-MS/MS) and accurate mass measurements (GC-HRMS). The studied compounds showed good peak shape and efficient GC separation with a GC-MS fragmentation pattern similar to that obtained by direct insertion probe. With the exception of galanthamine-N-oxide and N-formylnorgalanthamine, the galanthamine-type compounds showed abundant [M]+. and [M-H]+ ions. A typical fragmentation pattern was also observed, depending on the substituents of the skeleton. Based on the fragmentation pathways of reference compounds, three other galanthamine-type alkaloids, including 3-O-(2′-butenoyl)sanguinine, which possesses a previously unelucidated structure, were identified in Leucojum aestivum ssp. pulchelum, a species endemic to the Balearic islands. GC-MS can be successfully applied to Amaryllidaceae plant samples in the routine screening for potentially new or known bioactive molecules, chemotaxonomy, biodiversity and identification of impurities in pharmaceutical substances. Copyright © 2012 John Wiley & Sons, Ltd.


Mandal P.K.,University of Leeds | Branson T.R.,University of Leeds | Hayes E.D.,University of Leeds | Ross J.F.,University of Leeds | And 3 more authors.
Angewandte Chemie - International Edition | Year: 2012

It has long been known that people with blood group O are more severely affected by El Tor cholera than those with blood groups A or B. Microcalorimetry and NMR spectroscopy are used to evaluate the ability of the B-subunits of cholera toxin and E. coli heat-labile toxin to bind to selected blood group oligosaccharides. Copyright © 2012 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Carrillo R.,CSIC - Institute of Natural Products and Agrobiology | Morales E.Q.,CSIC - Institute of Natural Products and Agrobiology | Martin V.S.,Instituto Universitario Of Bio Organica Antonio Gonzalez | Martin T.,CSIC - Institute of Natural Products and Agrobiology | Martin T.,Instituto Universitario Of Bio Organica Antonio Gonzalez
Journal of Organic Chemistry | Year: 2013

Positive cooperativity between host conformational equilibria and guest binding has been widely reported in protein receptors. However, reported examples of this kind of cooperativity in synthetic hosts are scarce and largely serendipitous, among other things because it is hard to envision systems which display this kind of cooperativity. In order to shed some light on the correlation between conformational equilibria of free host and guest binding, selected structural modifications have been performed over a family of nonpreorganized hosts in order to induce conformational changes and to analyze their effect on the binding affinity. The conformational effect was evaluated by a theoretical conformational search and correlated with the ability of the receptors. All data suggest that those receptors that display the best association constants are able to sample folded conformations analogous to the conformational requirements for the binding of the guests. On the contrary, for those receptors where folded conformers are scarce, then the association constant and enantioselectivity clearly drop. © 2013 American Chemical Society.


Carrillo R.,CSIC - Institute of Natural Products and Agrobiology | Morales E.Q.,CSIC - Institute of Natural Products and Agrobiology | Martin V.S.,Instituto Universitario Of Bio Organica Antonio Gonzalez | Martin T.,CSIC - Institute of Natural Products and Agrobiology | Martin T.,Instituto Universitario Of Bio Organica Antonio Gonzalez
Chemistry - A European Journal | Year: 2013

Cooperativity is one of the most relevant features displayed by biomolecules. Thus, one of the challenges in the field of supramolecular chemistry is to understand the mechanisms underlying cooperative binding effects. Traditionally, cooperativity has been related to multivalent receptors, but Williams etal. have proposed a different interpretation based on the strengthening of noncovalent interactions within receptors upon binding. According to such an interpretation, positive cooperative binding operates through structural tightening. Hence, a quite counterintuitive kinetic behavior for positively cooperative bound complexes may be postulated: the more stable the complex, the slower it is formed. Such a hypothesis was tested in a synthetic system in which positive cooperative binding was previously confirmed by calorimetric experiments. Indeed, a linear correlation between the thermodynamics (ΔG°) and the kinetics (ΔG≠) of guest binding confirmed the expected behavior. These distinctive kinetics provide solid evidence of positive cooperative guest binding, which is particularly useful bearing in mind that kinetic experiments are frequently and accurately carried out in both synthetic and biological systems. Copyright © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.


Cedron J.C.,Instituto Universitario Of Bio Organica Antonio Gonzalez | Cedron J.C.,Instituto Canario Of Investigacion Del Cancer Icic | Gutierrez D.,Higher University of San Andrés | Flores N.,Higher University of San Andrés | And 4 more authors.
Bioorganic and Medicinal Chemistry | Year: 2010

Twenty seven lycorine derivatives were prepared and evaluated for their in vitro antimalarial activity against chloroquine-sensitive strains of Plasmodium falciparum. The best antiplasmodial activities were achieved with lycorine derivatives that present free hydroxyl groups at C-1 and C-2 or esterified as acetates or isobutyrates. The double bond C-2-C-3 is also important for the activity. Concerning to the antiplasmodial activity of the secolycorines, the higher values were obtained with the replacement of the methylenedioxy moiety by hydroxyl or acetate groups and with methyl substituent attached to the nitrogen atom. © 2010 Elsevier Ltd. All rights reserved.

Loading Instituto Universitario Of Bio Organica Antonio Gonzalez collaborators
Loading Instituto Universitario Of Bio Organica Antonio Gonzalez collaborators