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Guedes G.,University of La Laguna | Guedes G.,Instituto Canario Of Investigaciones Del Cancer Icic | Lopez-Rodriguez M.,University of La Laguna | Ravelo A.G.,University of La Laguna | And 3 more authors.
European Journal of Organic Chemistry | Year: 2012

Several disubstituted angular naphthoimidazoles have been synthesized by a new domino reaction from (1,4-dimethoxynaphthalen-2-yl)amine (1) and imines (obtained from 1 and aromatic aldehydes) in the presence of Sc(OTf) 3. A plausible pathway for the reaction involves attack of the nucleophilic amine on the imine and further reaction of the resulting intermediate by intramolecular cyclization with loss of a methoxy group and subsequent oxidation to yield the final naphthoimidazole. These naphthoimidazoles were also obtained in lower yields from aromatic aldehydes, Sc(OTf) 3 and 2 equiv. of 1 through an ABB' domino process. Post-condensation transformations allowed direct access to several derivatives. © 2012 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim.


Pena R.,University of La Laguna | Pena R.,Instituto Canario Of Investigaciones Del Cancer Icic | Jimenez-Alonso S.,University of La Laguna | Jimenez-Alonso S.,Instituto Canario Of Investigaciones Del Cancer Icic | And 10 more authors.
Journal of Organic Chemistry | Year: 2013

A series of dihydropyran and dihydropyridin embelin derivatives were synthesized through a novel and straightforward one-pot protocol based on a three-component reaction with embelin, aldehydes, and cyclic enaminones as synthetic imputs. The type of substituent on the nitrogen atom of the β-enaminone is key to obtain nitrogenated or oxygenated rings. The obtained compounds were active against Gram-positive bacteria, including multiresistant Staphylococcus aureus clinical isolates. © 2013 American Chemical Society.


Hueso-Falcon I.,University of La Laguna | Hueso-Falcon I.,Instituto Canario Of Investigaciones Del Cancer Icic | Cuadrado I.,Complutense University of Madrid | Cidre F.,Institute Salud Carlos III | And 7 more authors.
European Journal of Medicinal Chemistry | Year: 2011

A series of kaurene derivatives (1-63) were prepared and evaluated for anti-inflammatory activity. Thirteen of the tested compounds were able to inhibit NO production with an IC50 between 2 and 10 μM. Compounds 11, 12, 14 and 23 showed low percentage of cell viability, whereas compounds 9, 10, 17, 28, 37, 48, 55, 61 and 62 were non-cytotoxic at the concentration up to 25 μM. Some structure-activity relationships were outlined. Compounds 28, 55 and 62, were selected as representative compounds and they potently inhibited the protein expression of NOS-2. We also determined that inhibition of NF-κB activation might be the mechanism involved in anti-inflammatory effects of these kaurene derivatives. As expected, cytokines IL-6, IL-1α, TNF-α and IFN-γ were downregulated in the presence of compound 28, 55 and 62 after stimulation with LPS. These results indicate that kaurene derivatives might be used for the design of new anti-inflammatory agents. © 2011 Elsevier Masson SAS. All rights reserved.


Oramas-Royo S.,University of La Laguna | Oramas-Royo S.,Instituto Canario Of Investigaciones Del Cancer Icic | Torrejon C.,Complutense University of Madrid | Cuadrado I.,Complutense University of Madrid | And 5 more authors.
Bioorganic and Medicinal Chemistry | Year: 2013

In the present study, a series of metallic complexes of the 1,4-naphthoquinone lawsone (2-6) were synthesized and evaluated for potential cytotoxicity in a mouse leukemic macrophagic RAW 264.7 cell line. Cell viability was determined by the MTT assay. Significant growth inhibition was observed for the copper complex (4) with an IC50 value of 2.5 μM. This compound was selected for further evaluation of cytotoxic activity on several human cancer cells including HT-29 (human colorectal adenocarcinoma), HepG2 (human hepatocellular carcinoma) and HeLa, (human cervical adenocarcinoma cells). Significant cell viability decrease was also observed in HepG2 cells. The apoptotic potential of this complex was evaluated in these cells. Compound 4 induced apoptosis by a mechanism that involves the activation of caspases 3, 8 and 9 and modulation of apoptotic-related proteins such as Bax, Bad, and p53. These results indicate that metal complexes of lawsone derivatives, in particular compound 4, might be used for the design of new antitumoral agents. © 2013 Elsevier Ltd. All rights reserved.


Jimenez-Alonso S.,University of La Laguna | Jimenez-Alonso S.,Instituto Canario Of Investigaciones Del Cancer Icic | Guasch J.,CIBER ISCIII | Estevez-Braun A.,University of La Laguna | And 5 more authors.
Journal of Organic Chemistry | Year: 2011

The electronic properties of a new set of cytotoxic 2-amino-naphtho[2,3-b] furan-4,9-dione derivatives (1-8) are evaluated. The electron delocalization of these compounds is described by means of their redox potentials and solvatochromic properties. The large solvatochromism of their intramolecular electron transfer band is analyzed using the linear salvation energy relationship method. In addition, this method determined the importance of the molecular environment, quantifying the interactions that compounds (1-8) establish with their surrounding media, with the capacity of acting as hydrogen-bond acceptors (HBA) and hydrogen-bond donors (HBD) and the dipolarity/polarizability being the most significant ones. As a result, a relationship between the electronic and the cytotoxic properties of these compounds is proposed. © 2011 American Chemical Society.


Perez-Labrada K.,CSIC - Institute of Natural Products and Agrobiology | Perez-Labrada K.,University of Habana | Brouard I.,CSIC - Institute of Natural Products and Agrobiology | Brouard I.,University of Las Palmas de Gran Canaria | And 6 more authors.
Tetrahedron | Year: 2011

Novel analogs of spirostan saponins in which the glycosidic bond has been replaced by a triazole linkage are described. For this, a direct oligosaccharide-steroid conjugation approach based on the Cu I- catalyzed azide-alkyne 1,3-dipolar cycloaddition was implemented, leading to diverse combinations of saponin analogs with variations in the trisaccharide moiety, the artificial linkage, and the steroid-skeleton functionalization. This 'click' process proved great efficiency for the ligation of two bulky building blocks (e.g., chacotriose derivatives and spirostanes bearing axial azides), which enabled the rapid creation of a small library of triazole-based analogs for cytotoxicity evaluation. A molecular modeling study was performed to understand the conformational and electronic differences between a natural saponin and its triazole-based analogs. © 2011 Elsevier Ltd. All rights reserved.

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