oalib

Publish in OALib Journal

ISSN: 2333-9721

APC: Only $99

Submit

Any time

2019 ( 25 )

2018 ( 33 )

2017 ( 45 )

2016 ( 55 )

Custom range...

Search Results: 1 - 10 of 17052 matches for " Sara Montiel-Smith "
All listed articles are free for downloading (OA Articles)
Page 1 /17052
Display every page Item
Motor Effects of 1,3-Disubstituted 8-Styrylxanthines as A1 and A2 Adenosine-Receptor Antagonists in Rats  [PDF]
Ilhuicamina Daniel Limón-Pérez de León, María del Carmen Parra-Cid, Alejandro Mu?oz-Zurita, Saúl Alejandro Merino-Contreras, Sara Montiel-Smith, Socorro Meza-Reyes, Gerardo Ramírez-Mejía, Jesús Sandoval-Ramírez
Pharmacology & Pharmacy (PP) , 2013, DOI: 10.4236/pp.2013.43044
Abstract:

A series of 1,3-substituted 8-styrylxanthines (11a-d) was synthesized, under chemo- and regioselective conditions, in a good overall yield. The compounds showed affinity towards both A1 and A2A-adenosine receptors by radioligand binding by means of in vitro assays. The (E)-3-ethyl-1-propyl-8-styrylxanthine (11a) showed the greatest affinity towards the A2A receptor, whereas (E)-3-pentyl-1-propyl-8-styrylxanthine (11d) showed the greatest affinity for the A1 receptor. When the 8-styrylxanthines 11a (A15Et) and 11c (A15Bu) were administrated in rats, which were previously injured with 6-hydroxydopamine at the substantia nigra pars compacta (SNc), the turning behavior decreased 50%. Based on these results we propose to A15Et as a potential compound to treat some symptoms of Parkinson’s disease.

Side-chain opening of steroidal sapogenins to form 22-oxocholestanic skeletons: An approach to analogues of the aglycone of the potent anticancer agent OSW-1
Fernández-Herrera, María A.;Sandoval-Ramírez, Jesús;Meza-Reyes, Socorro;Montiel-Smith, Sara;
Journal of the Mexican Chemical Society , 2009,
Abstract: the side-chain opening of 25r and 25s steroidal sapogenins to form 22-oxocholestanic skeletons is described. the transformation was produced under mild conditions providing high yields (70-87%), in a one pot procedure (some acetylated starting material is recovered). this methodology yields 17-deoxy-26-oxy analogues of the aglycone of the potent anticancer agent osw-1. all products were fully characterized by 1d and 2d nmr; the most representative displacements are briefly discussed.
Side-chain opening of steroidal sapogenins to form 22-oxocholestanic skeletons. An approach to analogues of the aglycone of the potent anticancer agent OSW-1
María A. Fernández-Herrera,Jesús Sandoval-Ramírez,Socorro Meza-Reyes,Sara Montiel-Smith
Revista de la Sociedad Química de México , 2009,
Abstract: Se reporta la apertura de la cadena lateral de sapogeninas esteroidales 25R y 25S para obtener estructuras 22-oxocolestánicas. La transformación fue llevada a cabo bajo condiciones de reacción suaves y con altos rendimientos (70-87%), en un solo paso (se recupera materia prima acetilada). Con esta metodología se obtienen, en un solo paso, análogos 17-desoxi-26-oxigenados de la aglicona del potente anticancerígeno OSW-1. Todos los productos fueron caracterizados por RMN de una y dos dimensiones y los desplazamientos más representativos se discuten brevemente.
Synthesis and Absolute Configuration of (20R)-20-Acetyl-23,24- bisnorcholanic Lactones Prepared from (E)-(20S,25R)- and (E)-(20S,25S)- 20,23-Diacetylfurost-22-enes
Guadalupe Hernández Linares,Socorro Meza Reyes,Sara Montiel Smith,Jesús Sandoval Ramírez
Revista de la Sociedad Química de México , 2007,
Abstract: Se reporta la síntesis de lactonas (20R)-20-acetil-23,24- bisnorcolánicas a partir de (E)-(20S,25R)- y (E)-(20S,25R)-(E)-20,23- diacetilfurost-22-enos (obtenidos a partir de diosgenina, hecogenina y sarsasapogenina). La configuración del centro estereogénico C-20 fue determinada por estudios de RMN y difracción de rayos X de monocristal. Las lactonas pueden ser usadas en la síntesis de una variedad de derivados esteroidales.
(E)-(25S)-23-Acetyl-5β-furost-22-ene-3β,26-diol
María-Guadalupe Hernández Linares,Jesús Sandoval Ramírez,Socorro Meza Reyes,Sara Montiel Smith
Acta Crystallographica Section E , 2008, DOI: 10.1107/s1600536808004509
Abstract: The title steroid, C29H46O4, is a furostene derivative with a C=C double-bond length of 1.353 (3) and an E configuration. The side chain is oriented toward the α face of the A–E steroidal nucleus and presents a disordered terminal CH2—OH group [occupancies for resolved sites are 0.591 (9) and 0.409 (9)]. The methyl group at C20 attached to ring E is also oriented toward the α face, avoiding steric hindrance with the carbonyl O atom of the acetyl group. The furostene and acetyl functionalities form an α,β-unsaturated ketone system, with an s-cis configuration. All hydroxy and carbonyl groups are involved in weak intermolecular hydrogen bonds. The absolute configuration was assigned from the synthesis.
The zwitterion (23′E)-(23R,25S)-23-[1-(oxidoiminio)ethyl]-5β-spirostan-3β-yl acetate
María-Guadalupe Hernández Linares,Jesús Sandoval Ramírez,Socorro Meza Reyes,Sara Montiel Smith
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809044651
Abstract: The title steroidal compound, C31H49NO5, resulted from the selective oximation of (23R)-23-acetylsarsasapogenin acetate. One- and two-dimensional 1H and 13C NMR spectra, as well as IR data, are in agreement with the presence of a ketoxime group at C-23. However, recrystallization in slightly acidic media affords the title compound in the rare zwitterionic oxime form, as a consequence of migration of the hydroxy H atom to the N atom in the oxime group. This H atom is clearly detected and its position was refined from X-ray data. The geometry for the C=N+(H)—O group features long C=N and short N—O bond lengths compared to non-zwitterionic oximes. The ketoxime is stabilized with the E configuration, avoiding steric hindrance between the oxime O atom and H atom at C-23. The sum of the angles around the oxime N atom is 359.6°, giving a planar configuration for that atom, as expected for sp2 hybridization.
(20S,2′′S)-20-[4′-(3′′-Hydroxy-2′′-methylpropyl)-3′-methylisoxazol-5-yl]-5β-pregnan-3β,16β-diol
María-Guadalupe Hernández Linares,Jesús Sandoval Ramírez,Socorro Meza Reyes,Sara Montiel Smith
Acta Crystallographica Section E , 2009, DOI: 10.1107/s1600536809050478
Abstract: The title steroidal compound, C29H47NO4, was prepared in a one-pot reaction starting from a sarsasapogenin derivative of known configuration. The isoxazole heterocycle is oriented towards the α face of the steroid nucleus and, although fully functionalized on C atoms, does not provoke steric hindrance with the adjacent D ring. The absolute configuration observed for chiral centers is as expected, and shows that no epimerization occurred in the precursors. In the crystal, the three OH groups serve as donors for hydrogen bonding with O and N atoms. The isoxazole N atom is involved in O—H...N hydrogen bonds, forming chains along [100]. These chains are further connected via O—H...O and weak C—H...O contacts, giving rise to a three-dimensional supramolecular network.
A convenient procedure for the synthesis of 3beta-hydroxy-6-oxo-5alpha-steroids: aplication to the synthesis of laxogenin
Iglesias-Arteaga, Martín A.;Símuta-Lopez, Eva M.;Xochihua-Moreno, Sergio;Vi?as-Bravo, Omar;Smith, Sara Montiel;Meza Reyes, Socorro;Sandoval-Ramírez, Jesús;
Journal of the Brazilian Chemical Society , 2005, DOI: 10.1590/S0103-50532005000300011
Abstract: a convenient pathway to obtain 3b-hydroxy-6-oxo-5a-steroids from 3b-acetoxy d5-steroids is reported; the methodology was applied to the synthesis of laxogenin (7), substance that behaves as a plant growth hormone. this is an alternative way to produce an important functionality found in many examples of naturally occurring steroids. the developed procedure uses inexpensive reagents and can be carried out in four steps. the oxidizing and acidic steps used in this methodology did not affect the labile spiroketal side chain present in diosgenin (16).
Teaching Language and Content: Instructor Strategies in a Bilingual Science Class at a Chinese University
Xiaoping Liang,Sara W. Smith
International Journal of Higher Education , 2012, DOI: 10.5430/ijhe.v1n2p92
Abstract: This research explores the role of English as a medium of instruction and a focus of learning in a bilingual science class taught in Chinese and English as a foreign language. It examines how the instructor handles meaning and form of new English science vocabulary in concept-focused physics lectures and the strategies he uses in doing so. Analysis of classroom instructional discourse demonstrates that the instructor took an integrative approach in dealing with the meaning-form association of new science vocabulary. He employed a variety of strategies to lighten vocabulary load and to increase comprehensibility of physics lectures. The results indicate that there is a place for language instruction in bilingual science classes. Bilingual science instructors are encouraged to integrate language with the subject matter they teach and provide students opportunities for simultaneous development of content and language.
On Macroeconomic Reforms and Macroeconomic Resiliency: Lessons from the Great Recession  [PDF]
Peter J. Montiel
Modern Economy (ME) , 2011, DOI: 10.4236/me.2011.24058
Abstract: What are the payoffs from macroeconomic reforms? Whether such reforms yield higher long-term growth has long been controversial. However, the experience of the Great Recession suggests that other important benefits may have been neglected in the controversy over the growth benefits of reform. Specifically, in contrast with previous international recessions, recovery from the Great Recession has been led by emerging and developing economies, many of which have implemented significant reforms over the past two decades. How much of the resilience of these economies can be attributed to these reforms, and what do these lessons suggest for the desirability of further reforms? This paper is intended to provide some preliminary answers to these questions.
Page 1 /17052
Display every page Item


Home
Copyright © 2008-2017 Open Access Library. All rights reserved.