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Acevedo Acevedo, Delgado; Leon-Velasquez, Madeline; Cortes-Figueroa, Jose E. Department of Chemistry, UPR-Mayagüez.
A biphasic displacement of 1,10-phenanthroline from fac-(dihapto-phenanthroline) (dihapto-[60]fullerene) tricarbonylmolybdenum(0) by triphenylphosphine
Triphenylphosphine displaces 1,10-phenanthroline from fac-(dihapto-phenanthroline)(dihapto-[60]fullerene)tricarbonylmolybdenum(0). The reaction was studied under flooding conditions where the molar concentration of triphenylphosphine was at least 10,000 times the molar concentration of fac-(dihapto-phenanthroline)(dihapto-[60]fullerene)tricarbonylmolybdenum(0). The reactions' progress were followed by measuring the absorbance at 440 nm. Plots of absorbance - absorbance infinity vs. time showed a biphasic behavior. This observation suggest that [60]fullerene is a cis labilizing ligand. The mathematical description to resolve the biphasic plot into two consecutive first order reactions will presented in detail. Acknowledgments are made to the Petroleum Research Fund (PRF 36623-B3), Administered by the American Chemical Society, to National Science Foundation (CHEM-0102167) for support of this work. DAA received financial support from PR-LSAMP.
Aviles, Yadriel; Alejandro Blanco; Samuel P. Hernández-Rivera. Center for Chemical Sensors Development for Explosives, Department of Chemistry. University of Puerto Rico. Mayagüez.
Investigación espectroscópica de 2,4-DNT y 2,6-DNT y sus interacciones con particulas de silica
A través de los años, como parte de conflictos bélicos, los dispositivos explosivos más se utilizados son minas terrestres. Las mismas son cargas explosivas que se colocan bajo suelo y luego se detonan por contacto. Existen miles de minas enterradas distribuidas atraves de 70 países en todo el mundo. Hasta hace poco tiempo era factible utilizar detectores de metales para detectar este tipo de artefactos explosivos. Hoy en día las minas se colocan en envases de plástico. Otro problema es que la técnica es incapaz de detectar pequeñas cantidades de cristales de explosivos. La Espectroscopia de Raman es una herramienta establecida para análisis de espectroscopia vibracional. La interacción de explosivos con diferentes substratos puede ser estudiada de información del desplazamiento cuantitativo de señales vibracionales Raman asociada con dicha interacción. Se hizo un estudio de espectroscopia vibracional para cristales de 2,4-DNT y 2,6-DNT. Para esto se utilizó un microscopio de Raman equipado con una línea de excitación láser de 514 nm. Las muestras se recristalizaron en diferentes solventes (agua, metanol y acetonitrilo) y luego se expusieron a la interacción con sílice. La interacción con silica gel dopadas con compuestos nitroaromáticos mostraron un desplazamiento significativo en las señales de los espectros. Esta información se utilizó para detectar DNT en muestras de silica usando Microscopia de Raman. También se midió la variación del desplazamiento de la señal Raman a diferentes valores de pH (4, 7 y 9). Estos resultados pueden servir de base para desarrollar nuevos sensores para detección de materiales explosivos.
Benítez, Jaime; Marrero, Jeffrey; Rodríguez, Abimael D. Department of Chemistry, University of Puerto Rico, Río Piedras.
Isolation and structural elucidation of two highly oxygenated cembranoids diterpenoids from the Sea Plume Pseudopterogorgia kallos
The chemical study of the chloroform extract from the Colombian Sea Plume Pseudopterogorgia kallos resulted in the isolation of two new highly oxygenated cembranoids diterpenes, bipinnatin K (1) and L (2). Their chemical structures were elucidated using 1D- and 2D NMR experiments (HMQC, 1H-1H COSY, HMBC, and NOESY) in combination of UV, IR, and HR-MS analysis. The biological activity of the forementioned compounds are currently under study.
Borrero, Solmarie; Santiago, Mitk'El; Guadalupe, Ana R.; Colón, Jorge L. Chemistry Department, University of Puerto Rico, Rio Piedras.
Synthesis, characterization and intercalation of [Co(tpy)2](PF6)2 into the 10.3 Å phase of layered zirconium phosphate
Zirconium phosphates (ZrP), which are acidic, inorganic, ion exchangers with layered structures, have been extensively investigated. We are investigating the use of these materials as hosts for inorganic complexes using a 10.3 Å phase of ZrP, which we have recently demonstrated directly exchanges large metal complexes. The inorganic complex chosen for our studies is [Co(tpy)2](PF6)2, an electron mediator suitable for biosensor applications. The synthesis of the 10.3 Å ZrP phase, [Co(tpy)2](PF6)2, and were successful and all materials were characterized. The characterization was done using X-Ray Powder Diffraction, Infrared Spectroscopy, and UV-visible spectrophotometry. Carbon paste electrodes were modified with [Co(tpy)2]2+-exchanged ZrP. The electrochemical characterization of this material will also be presented. S.B.M. acknowledges the financial support of the PR-LSAMP program. M.B.S. acknowledges the financial support of NIH-RISE/SUBE Graduate Fellowship.
Burgos-Frontanes, Samuel; Leonardo Pacheco Londoño; Oliva M. Primera Pedrozo; Samuel P. Hernandez Rivera. Centro de Desarrollo de Sensores Químicos para la Detección de Explosivos, Departamento de Quimica, University of Puerto Rico-Mayagüez.
Estudio de fases de RDX a diferentes concentraciones de cristalización en superficies
Existen cuatro confórmeros de RDX, en fase gaseosa. En sólida solo se han descubierto dos de estos confórmeros, los cuales producen dos fases estables: RDX- y RDX-. Cuando se tiene RDX en solución y se deposita en una superficie este forma una de las dos fases. La forma en la cual condense depende de la superficie, de la concentración, de la cantidad depositada y del solvente. En este trabajo se variaron estos cuatro parámetros, encontrando que la concentración y la cantidad depositada eran los factores más influyentes en la cristalización. Para una superficie como acero inoxidable no-magnético tipo 316 se encontró que depositando 20 µL a una concentración mayor de 200 ppm de RDX en acetonitrilo se produce RDX- y a concentraciones RDX- es más estable y se produce en forma prominente, aunque no exclusivamente. La verificación de las fases se hizo mediante Microscopia Raman, FT-IR y FT-IR acoplado a fibra óptica con sonda de Angulo de rozamiento.
Campbell, Muriel; Sanoguet Zuleika. Chemistry Department, UPR-Mayagüez – Hu, Haitao; Chazin, Walter. Center for Structural Biology, Vanderbilt University – Pastrana, Belinda. Chemistry Department, UPR-Mayagüez.
Characterization of phosphorylated Chlamydomonas centrin
Centrin, a 20 kD protein, is a member of the calmodulin superfamily of EF-hand calcium binding proteins. It plays an essential role is centrosome duplication by mediating chromosome segregation during mitosis. Centrin was originally cloned at the DNA level from the unicellular green algae Chlamydomonas reinhardtii. Since then, homologs of centrin have been identified in yeast, mice, and humans, among other species. Centrin has two structurally independent domains connected by a flexible linker. The C- terminal domain of centrin (CRC-C) has a PKA phosphorylation site at serine 167. In vitro phosphorylation was performed on both, full length centrin and CRC-C, in order to analyze the effects of phosphorylation on the protein’s conformation. Differential Scanning Microcalorimetry was performed on both samples. The results suggest that phosphorylated centrin adopts a slightly different conformation and is less stable than the unphosphorylated form of centrin.
Cardona, Rocío del A.; Muñoz, Lisa; Guadalupe, Ana R. Department of Chemistry, University of Puerto Rico, Río Piedras Campus.
Development of a DNA sensor using peptide nucleic acid (PNA) as a probe attached to polystyrene films
The need for fast detection of harmful bacteria and other pathogens has lead the scientific community to study new sensor probes and devices. Peptide Nucleic Acid (PNA), a DNA synthetic analog, is a new tool in nucleic acid research. This molecule posses many of DNA properties but also present promising features because of its capacity to form more rigid structures, better hybridization and to detect bases mismatches. Due to its properties PNA has been used as a probe in the construction of DNA biosensors. Thin films of polystyrene functionalized with succinimide were prepared over gold substrates. PNA chains modified with amino groups were immobilized in the polymer surface. The complementary DNA sequence for PNA was labeled with a ferrocene complex. The hybridization was monitored by the redox process of ferrocene using Osteryoung Square Wave Voltammetry (OSWV). Atomic Force Microscopy (AFM) and X-Ray Photoelectron Spectroscopy (XPS) were used to determine morphology changes after immobilization and hybridization. The electrochemical studies showed that the response time for double strand formation were around 60 min. Using AFM and XPS the formation of the double strand was also confirmed after changes in surface morphology and elemental analysis, respectively. To complete the development of our DNA/PNA sensor a calibration curve will be construct to evaluate the usable concentration range and the sensor analytical parameters.
Caro-Gautier, Humberto. Institute for Tropical Ecosystem Studies, University of Puerto Rico Rio Piedras and Department of Chemistry, University of Puerto Rico Rio Piedras - J. Lugo Vega; R. Ríos Dávila. Graduate School of Public Health, Department of Environmental Health, Medical Sciences Campus, University of Puerto Rico, San Juan - Mayol-Bracero, O.L. Institute for Tropical Ecosystem Studies, University of Puerto Rico Rio Piedras and Department of Chemistry, University of Puerto Rico Rio Piedras.
Deposition of carbonaceous aerosol particles on the historical building “Ruinas de Caparra” in Puerto Rico
Atmospheric aerosols are collections of small particles suspended in the air originating from natural and anthropogenic sources. Carbonaceous aerosol particles (CAs), mainly composed of elemental and organic carbon (EC and OC), damage monuments and historical building around the world. These particles have been found in the inner surface of stone and mortars of historical buildings (mostly in Europe), generating the degradation of these materials by means of such chemicals reactions as the sulphatation of calcium carbonate into gypsum. The purpose of this study is to investigate the relationship between the soiling produced by carbonaceous aerosol particles and the formation of the black patina on the surface layers of “Ruinas de Caparra”. Samples of the patinas were collected at several points from the upper and side surfaces of the ruins. Analyses of these samples were performed according to the procedure developed by Ghedini et al., 2000. Scanning electron microscope (SEM) with energy dispersive spectrometry was used for the study of the morphology and elemental composition of the particles deposited on the surface of the collected samples. The determination of water-soluble ions (SO3-2, SO4-2, NO3-), was performed using ion chromatography. Parallel to these analyses, air sampling with a low-pressure impactor was also performed for the determination of the size resolved EC and OC concentrations to which the ruins are exposed on a daily basis. Preliminary results of this study will be discussed in this presentation.
Cartagena, Michelle; Reyes, Elba D. Chemistry Department, University of Puerto Rico, Cayey Campus.
Creating methodology to determine chemical changes of infusions
In Puerto Rico, infusions of plants with therapeutic effects are very useful but sometimes dangerous for the health. For many plants used to treat different illnesses, no phytochemical information are reported, therefore, nobody knows of possible secondary effects or side reactions that will happen due to changes in pH or side reactions with other synthetic drugs. The main goal of this research is to study the chemical changes of the plant compounds that have therapeutic effects (metabolites), which are namely ingested by humans. In particular, we want to answer the following questions: 1) Do the compounds present in an active extract suffer chemical changes at different pHs and temperatures? 2) Are all the organic compounds present or extracted from one source present in the infusions prepared by the population? We expect to: a) probe qualitatively if the general organic composition at specific infusions suffers chemical changes with lower or neutral pH’s; b) compare the total chemical compositions of the whole crude MeOH extracts of Citrus aurantium L. and Annona reticulata leaves with the extracted chemical composition in the aqueous phase when the infusions are prepared, and c) characterize the crude extracts presenting chemical changes. Preliminary TLC results, analyzing infusion extracts from leaves of Citrus aurantium L. and Annona reticulata (after mimicking human digestion, specifically stomach and plasma pH and corporal temperature) reveals irreversible chemical changes when the pH rises to 7.4. These preliminary results demonstrate that chemical changes could be occurring during the bioassays implicating that biological activity could be due to the chemical changes promoted by the extracts instead of natural metabolites. Extracts presenting chemical changes are submitted to Probit analyses, using brine shrimp as live source to probe citotoxicity. ED50 values and partially characterization of organic compounds using chromatographic (TLC, CC, GC) and spectroscopic techniques (IR, MS) will be presented.
Castillo Rivera, Dorianne A; Rodriguez Reyes, David; Prieto, Jose A. Chemistry Department, UPR-Rio Piedras.
Studies toward the synthesis of Rifamycin S ansa chain
Rifamycin S is a member of the ansamycin family of antibiotics. Its structure consists of an aliphatic ansa chain with eight consecutives stereogenic centers and an aromatic portion. In order to construct the polypropionate array, we are currently working in a reiterative approach that consists in the stereoselective synthesis of epoxides, followed by a regioselective cleavage process with an organometallic compounds. Following the proposed work, we epoxidized Ethyl trans crotonate with 3-chloroperoxybenzoic acid (mCPBA) in moderate yield. This epoxide was cleaved with diethylpropynylalane in high yield (80%) and the alkynyl ester was transformed into its corresponding alkynyl acid in quantitative yield using microwave technology. Then, a trans reduction of the alkyne functionality was performed in very high yield under sodium/ammonia conditions (95-100%). Iodolactonization followed by methanolysis produced a second epoxy ester (56%). Since the cleavage of this epoxide showed to be problematic , we are working in the reduction of the ester functionality and protection of the resulting primary alcohol before exposing the epoxide to the cleavage process. At this stage, we have synthesized six of the stereogenic centers of Rifamycin S. Currently, we are investigating the best reaction conditions to finally incorporate the remaining two stereogenic centers of the ansa chain. Work supported by NIH RISE (R25-GM-061151) and NIH SCORE (S06GM-08102).
Cotto, Marlene; Miranda, Carlos.; Carballeira, Néstor M. Department of Chemistry, University of Puerto Rico, Rio Piedras.
The total synthesis of (+)-2- methyldecanoic acid, a potential antimycobacterial fatty acid
Biologically active compounds containing methyl branching are abundant in nature. The fatty acid (+)-2-methyldecanoic acid was synthesized in three steps starting from commercially available decanoic acid. This synthesis provided sufficient quantities for biological evaluation against Mycobacterium tuberculosis H37Rv. The previously synthesized 2-methoxydecanoic acid has demonstrated activity (99% inhibition) at 6.25 µg/mL against this strain of M. tuberculosis and such studies are underway.
M.Cotto thanks the UPR-RP RISE program for an undergraduated fellowship
Crespo-Román, Gisela; Ocasio-Delgado, Yessenia; Cortes-Figueroa, Jose E. Department of Chemistry, UPR-Mayagüez.
Mechanisms of ligand exchange reactions on (dihapto-[C60]fullerene) transition-metal carbonyl complexes
The Lewis bases (L) piperidine, triphenylphosphie, and triciclohylphosphine displace bidentate ligands (bidentate ligands = 1,2-bis(diphenylphosphino)ethane (dppe) and 1, 10-phenanthroline (phen)) from fac- and mer-(dihapto-C60)(dihapto-bidentate ligand)M(CO)3 to produce fac- and/or mer- (dihapto)(monohapto-L)2M(CO)3 and (monohapto-L)(dihapto-bidentate ligand)M(CO)3 (M = Cr, Mo, W). The reactions are first order with respect to the molar concentration of (dihapto-C60)(dihapto-bidentate ligand)M(CO)3. The order with respect to L is complex. The proposed mechanisms involve a competition between a L-assisted ring-opening of the chelate ring to produce the electronically-saturated intermediate (dihapto-C60)(monohapto-L)(monohapto-bidentate ligand)M(CO)3, solvent-assisted ring-opening of the chelate ring to produce the electronically-saturated intermediate (dihapto-C60)(solvent)(monohapto-bidentate ligand)M(CO)3 and a solvent-assisted dissociation of C60 producing the electronically-saturated species (monohapto-L)(dihapto-bidentate ligand)M(CO)3. These mechanisms differ from previously proposed mechanisms for the ligand exchange reactions of closely-related complexes such as fac-(monohapto-L)(dihapto-dppe)M(CO)3 (L = CO, piperidine, pyridine) and is contrary to the known cis labilizing property of dppe. These results suggest that [C60]fullerene has a strong steric influence on the inorganic moiety of the complex and on its chemical behavior. Acknowledgments are made to the Petroleum Research Fund (PRF 36623-B3), Administered by the American Chemical Society, and to National Science Foundation (CHEM-0102167) for support of this work.
Cruz, Nadya; Nieves, Ileana; Oyola, Rolando; García, Carmelo; Piñero, Luis; Rivera, Jessica; Department of Chemistry, UPR-Humacao.
Imipramines tricyclic drugs: An electrochemistry study in different solvents
The tricyclic anti-depressive drugs Imipramine (IPA), Desimipramine (DIPA) and Cloimipramine (CIPA) are of significant pharmaceutical importance because of their neuroleptic, sedative and antihistamic effects. Because these drugs are susceptible to changes in their molecular structures, the redox potentials of these drugs are relevant to understand their photoelectron transfer mechanism involving short-lived oxidation-reduction intermediates. The oxidation-reduction capability of a given derivative have been investigated in different solvents by Cyclic and Differential Pulse Voltammetry (CV and DPV, respectively) with a BAS CV-50 Voltammetric Analyzer controlled by the CV-50W version 2.3 software installed in a Pentium II computer. Results have shown that DIPA and IPA are easily oxidized compared to CIPA in the solvents used. As expected, the behavior of CIPA can be attributed to the chlorine induced electron withdrawing effect. In addition, CIPA shows the formation of two distinct oxidation intermediates when IPA/CIPA or DIPA/CIPA drug concentration ratio is changed in acetonitrile and methanol. Although the intermediates have not been characterized in these studies, the CV and DPV results may be correlated with the photochemical and photophysical response of these drugs related to the side effects. The gathered results are relevant for new drug development of efficient formulation with fewer side effects for the proper treatment of patients. Sponsored by Advance, NSF (SBE-0123645), UPR-Humacao
Cruz Moreira, Solimar; Ramos, Maiella, Department of Physics-Chemistry, University of Puerto Rico in Arecibo - Arbelo, José; Pantoja, Carlos; Mercado, Benjamín. Department of Biology, University of Puerto Rico in Arecibo.
Bioremediation of contaminated water with lead using Tropical plants in hydroponics cultures
Phytoremediation is a process of using plants to remove contaminants from the environment. The water hyacinth (Eichhornia crassipes) may be used as a sensitive bioindicator for continuously monitoring trace quantities of toxic heavy metals in aquatic systems. In this work we addressed the uptake of lead (Pb) by the water hyacinth aquatic plant. Hyacinth plants were grown in hydroponic solutions containing different concentrations of lead ranging from 0 ppm Pb to 10 ppm Pb. Levels of lead were determined in plant samples by means of an atomic absorption flame spectrometer. It was demonstrated that E. crassipes has a strong capability to accumulate higher lead concentrations in its roots than in its other parts. It was found that the concentrations of lead in the water hyacinth were higher than in the water. This heavy metal accumulated in the root tissues of water hyacinth may serve as a chemical marker for the evaluation of the remediation capabilities of this aquatic plant.
Delgado,
Dana; Nuñez, Daliangelis; Torres, Ivelisse; Rosario, Osvaldo.
Chemistry Department, UPR-Rio Piedras.
Isolation
and characterization of marine humic substances from seawater
Díaz,
Tanya; Malavé, María; Rivera, Mirna; Castillo, Jorge; Tremont,
Rolando. Department of Chemistry, UPR-Humacao.
Self-assembled
C26H24O2Fc on gold surface in ethanol solution
Gold
surface have been modified by self-assembled techniques. Controlling the
adsorption time of C26H24O2Fc at gold surface. This study was followed by
cyclic voltammetry (CV), electrochemical impedance spectroscopy (EIS), and
X-ray photoelectron spectroscopy (XPS) analysis. The method used for the
surface modification was the control of exposure time of gold surface in
the modifier/ethanol solution. By CV and EIS we demonstrated that the gold
surface was modified with C26H24O2Fc compound, avoiding the electron
transference in the interface. In the study by XPS we observed that the
organometallic molecule indeed has been adsorbed on the gold surface. In
addition, it was observed that the molecule-gold interaction is through
electrons of cyclopentadienyl, where the oxygen atoms are near the
air-molecule interface.
Domenech
Garcia, Maribella. Biotecnologia Industrial, UPR-Mayagüez
- McFallin, Jose Luis. Ingenieria Quimica, UPR-Mayagüez -
Velez, Gisselle. Quimica, UPR-Mayagüez - Justicia, Shandra.
Biotecnologia Industrial, UPR-Mayagüez - Rodriguez, Kristy;
Rodriguez, Lolita. Quimica, UPR-Mayagüez.
Effects
of aqueous extracts of baquiña in free calcium ion levels determined with
a calcium selective electrode
Para
identificar este posible principo activo hemos procedido a analizar los
constituyentes hidrosolubles presentes en las hojas de Baquiña. El
proceso de análisis de la planta, una vez las muestras se han secado (liofilización)
y molido (2 mm) ha consistido en realizar una extracción Soxhlet con agua
(5-10 gramos de material seco en 150 mL de agua), fraccionación por
filtración gel (Sephadex G-10 y G-25 fino y superfino) y estudio de las
fracciones resultantes por cromatografia líquida (HPLC, Alltima C18
5um, 27:73 acetonitrilo – agua). Resultados preliminares indican que hay
varias fracciones puras, llamándonos la atención un pico con tiempo de
retención de 4 minutos.
Echevarría
Torres, David; Santos, Lizette. Chemistry, PUCPR.
The effect of anticonvulsants on the microsomal cytochrome P450 monooxygenase system
The
liver is one of the most important organs involved in the metabolism of
exogenous and endogenous compounds in the body. The microsomal cytochrome
P450 monooxygenase system is present in the liver. This system play a
mayor role in the biotransformation of many compounds. The objective of
this study is to measure the effect of some anticonvulsants drugs on the
cytochrome P450 system. The anticonvulsants drugs to be studied are:
Tegretol (carbamazepine), Divalproex (depakote), Trilepal (oxcarbazepine)
and Dilantin (phenytoin). The isoenzymes that will be studied are CYP2C8
and CYP2C9. Microsomes will be prepare from Cricetulus griseus cells (CHO)
cells and treated with the anticonvulsants drugs. Enzyme activities will
be measured using HPLC Technique. Expected results will include the
determination of possible effects on the CYP2C8 and CYP2C9 isoenzymes.
Escalona,
Yma; Miller, Andrés. Natural Sciences Department, Inter American
University, Bayamón Campus.
Determinación
de concentración de plomo en árboles frutales silvestres, en la Isla de
Vieques
Flores,
Rosangelly; Brito, Rosa; Hernandez, Jessica; Cabrera, Carlos R.
Department of Chemistry, University of Puerto Rico-Rio Piedras.
DNA
density measurements using electrochemical methods on modified platinum
electrodes
García,
Rafael; Samuel P. Hernández-Rivera. Center for Chemical
Sensors Development for Explosives, Department of Chemistry,
Vibrational
spectroscopy and theoretical studies of transparent explosives
Explosives
are a special group of chemicals that have a high energy in their chemical
bonds that are able to release it in a short time in the form of hot
gases. In today’s modern world, explosives are important and
useful tools that play central roles in such as mining of mineral ores and
construction. In the political scene, explosives has been give a
more sinister and morbid use in terrorism. In the past the kind of
explosives that were used for terrorist application where somewhat common
and easily acquired in the international weapons underground market: black
powder, T.N.T, RDX and other military explosives. But these
explosives have an Aquiles heal, they can be detected in very small
quantities by the instruments (Ion Mobility Spectrometers) that the
transportation security agencies use. Being a very adaptable entity
terrorist, are now using exotic home-made explosives like Triacetone
Triperoxe (T.A.T.P) and Diacetone Diperoxe (D.A.T.P) that are virtually
invisible to current the technology used in these detection machines.
Our research centers in the analysis of this kind of chemical explosives:
Transparent Explosives and in the design of sensors for their detection.
In the initial experiments we combined different methodologies for
characterization and analysis. We used Spontaneous Raman
spectroscopy for vibrational characterization. Then the research
centered about to the use of silver colloids for applications of Surface
Enhanced Raman Spectroscopy. For target compounds we used model compounds
with similar characteristics with the transparent explosives. These
compounds are easier to use and have low toxicity.
García
Berríos, Edgardo; Elba Reyes; Raúl J. Castro. Department
of Chemistry,
In-situ
Friedel-Craft acylation of benzenethiol/Au self-assembled monolayers
Gavalda,
Salvador; Rodriguez, Jose; Smotkin, Eugene. Chemistry, UPR-Río
Piedras.
Preparation
and characterization of Cu/Zn/Al2O3 catalyst libraries for design of
experiments (DOE) development of water-gas-shift and/or methanol reforming
catalysts
Giménez,
Lizabeth; Sanabria, David; Cruz, Clarisa; Carballeira, Néstor.
Department of Chemistry,
The
synthesis of new fatty acids and their potential as antifungal compounds
Gonzalez,
Cristian. Chemical Engineering, UPR-Mayagüez -
Rivera, Luis A. Chemistry, UPR-Mayagüez.
Design,
synthesis, and characterization of potential biosensors for protein by
covalent immobilization of the amino acid threonine
Gonzalez
Freire, Carol L. Quimica, Universidad de Puerto Rico Recinto
de Rio Piedras - Quesada Gonzalez, Orestes. Estudios
Generales, Universidad de Puerto Rico Recinto de Rio Piedras -
Morales Guardia, Reginald. Quimica, Universidad de Puerto Rico Recinto de
Rio Piedras.
Possible
site of interaction of sanguinarine chloride and ipratropium
bromide on the human erythrocyte membrane
Gonzalez-Gonzalez,
Ileana; Tryk, Donald A.; Cabrera, Carlos R. Chemistry Department,
University of Puerto Rico, Rio Piedras Campus.
A
comparison of sulfur-doped and boron-doped diamond films as
electrocatalyst supports
Granell,
Laura; Pietri, Ruth; Lewis, Ariel; López-Garriga, Juan.
Chemistry, U.P.R.-Mayagüez Campus.
Determination
of the open and closed conformations of the hemoglobin II from Lucina
pectinata by FT-IR
Guillen,
Nancy; Narvaez, Daniel; Camacho, Carlos; Pastrana, Belinda.
Industrial Biotechnology, Chemistry Department, UPR-Mayagüez.
FT-IR
studies of EGFR ligands
Hernandez,
Emil; Castro, Miguel E. Chemistry, UPR-Mayagüez.
Nanoparticle
synthesis in a bubble: microreactors for selective nanoparticle synthesis
Hernández
Lugo, Dionne M.; García, Carmelo; Piñero, Luis E.; Oyola,
Rolando. Departamento de Química, Universidad de Puerto Rico
en Humacao.
Photophysical
properties of protriptyline and dibenzocycloheptene
Protriptyline
hydrochloride (PTL-HCl) is a tricyclic antidepressant and a skin
photosensitizing agent in humans. The mechanism of this cutaneous
photosensitivity is still unknown. It has been proposed that the
excited states and some of the short-lived intermediates of this drug are
directly associated with its in vivo phototoxic effects. Therefore
we have measured the photophysical properties of the protonated (PTL-HCl)
and unprotonated (PTL) forms of protriptyline and the parent molecule (dibenzocycloheptene,
DBCH). The ground and excited singlet state properties (molar extinction
coefficient, fluorescence quantum yield, fluorescence lifetime and
fluorescence quenching constant) were measured in methanol and
acetonitrile. The ground state properties are solvent and protonation
independent. The fluorescence quantum yield and lifetime, on the
other hand, strongly depend on the solvent. The quenching studies
were done in acetonitrile using diethyl and triethyl amine as quencher.
The Stern-Volmer quenching constants are also solvent dependent.
This work has been supported by NIH-MBRS Grant S06GM08216.
Justicia
Leon, Shandra D. Departamento de Biotecnologia Industrial,
UPR-Mayagüez - Souto Bachiller, Fernando; Rodriguez Rodriguez,
Lolita. Departamento de Quimica, UPR-Mayagüez -
Justicia Leon, Shandra D. Departamento de Biotecnologia Industrial,
UPR-Mayagüez - Velez Ruiz, Gisselle A.; Rodriguez Colon,
Kristy I. Departamento de Quimica, UPR-Mayagüez -
Domenech Garcia, Maribella. Departamento de Biotecnologia
Industrial, UPR-Mayagüez.
Fitoquimica de plantas medicinales diureticas: Rubia tinctorum
Rubia
tinctorum (R. tinctorum) es una
planta medicinal diurética utilizada tradicionalmente para tratar
calcificaciones, tales como la piedra del riñón, tracto urinario y
vejiga, compuestas fundamentalmente de oxalato y fosfato de calcio.
Existen múltiples testimonios de que las decocciones de esta planta
preparadas según el método tradicional (té), tienen la capacidad de
pulverizar dichas calcificaciones. Extracciones realizadas en el
laboratorio confirman que los extractos de R.
tinctorum son capaces de acomplejar sales de calcio solubles y
disolver las sales insolubles de oxalato y fosfato de calcio. El
acomplejamiento de calcio que presenta R.
tinctorum se le ha adjudicado preliminarmente a sus componentes
mayoritarios, alizarina, un pigmento anaranjado rojizo y purpurina,
amarillo. Un tercer componente lo es la lucidina, pigmento con alto grado
de toxicidad. El problema se fundamenta en que ninguno de los pigmentos
acomplejantes se encuentran en el extracto acuoso de la planta pues son
virtualmente insolubles en agua, por lo que se infiere la existencia de
otros componentes solubles. Candidatos posibles son los correspondientes
glicósidos solubles en solución acuosa. Para corroborar estas hipótesis,
actualmente se están realizando extracciones soxhlet con agua a partir de
las raíces de R. tinctorum,
fraccionación por ultracentrífuga o filtración gel de dichas
extracciones y, finalmente, estudios cromatográficos (HPLC) y
espectrofotométricos (UV-VIS) para determinar la composición y pureza de
fracciones recolectadas. La evidencia obtenida indica que hemos
aislado los glicósidos de alizarina y purpurina puros y que dichos glicósidos
muestran actividad antilítica determinada por el electrodo selectivo de
calcio. Además, no se puede decir que existen grandes cantidades del
componente tóxico, lucidina o sus glicósidos, en extractos de R.
tinctorum.
López
Pacheco, Lilibeth; Santos, Lizette. Chemistry,
El
efecto de un complejo multivitamínico en el sistema de citocromo P450
López-Alvarez,
Yania M. Industrial Biotechnology Program, UPR- Mayagüez
- López, Gustavo E. Department of Chemistry, UPR-Mayagüez.
Computational
studies of the liquid-liquid equilibrium in Lagmuir monolayers
Madero-Vergara,
Mayraliz; García Fraga, Oscar; Díaz-Vazquez, Liz; Rosario,
Osvaldo. Chemistry Department, UPR Río Piedras.
Effects
of extraction conditions and modifiers on the supercritical fluid
extraction of some persistent organic pollutants from sebum
Maldonado,
Omar D.; Castro, Raul. Quimica, U.P.R. Cayey.
Aplicaciones
de QCM y EQCM para el estudio de SAM’s
Phospholipase A2 competition in human erythrocyte studies using confocal microscopy
The
existence of different interactive sites in human erythrocyte was
confirmed by a series of binding studies that characterized the binding
isotherms of the basic phospholipase A2 (PLA2) from A. halys and one of
the PLA2 from N. nigricollis snake venom. The interaction of N.
nigricollis PLA2 is characterized by its Ca+2 requirement for binding and
had no acyl specificity in other hand, A. halys PLA does not require
calcium for binding, but does so for hydrolysis and its specificity is
dependent on enzyme concentration. These studies reveled that A.
halys interacted in a very limited number (5.2 x 107 per cells) of high
affinity sites. Competition studies demonstrated that at high levels (50
ug/mL cells) N. nigricollis PLA competed for the high affinity site of A.
halys PLA. Confocal Microscopy imaging of intact human erythrocyte
using A. halys and N. nigricollis PLA labeled with Alexa Fluor 488 and
Alexa Fluor 532 respectively confirm the binding studies and calcium
dependance. Flourescence profile of both PLA2 at concentration in
wich N. nigricollis displaced A. halys from its high affinity site were
obtained. (Supported by MARC Grant 5T34GM07821-24)
Martín,
Mariana; Rodríguez, David; Castillo, Dorianne; Prieto, José A.
Department of Chemistry,
A
new epoxide approach to polypropionate chains using trimethylalane
Mattei,
María de los A; Santos, Lizette. Chemistry Department,
Metal
content determination of the potable water at the Pontifical Catholic
University of Puerto Rico
Morales,
Eduardo M.; Ortiz, Margarita. Chemistry Deparment,
UPR-Humacao.
Synthesis of alpha silylated and alkylated O-tert-butyldimethyl silyl aromatic ketoximes
New
synthetic methods for the chemo and stereoselective synthesis of important
biologically active molecules are in grat demand. Reactions of metal
enolates and azaenolates are well-known methods for construction of C-Si
and C-C bonds. O-TBS ketoximes are novel precursors for the
synthesis of highly rective azaenolates, which can be alpha-C substituted.
We studied the alpha silylation and alkylation of O-TBS substituted
aromatic cyclic and acyclic ketoximes with LDA under several reactions
conditions. Complete conversion and high yields were afforded for
the silylation of O-TBS-4-metoxyacetophenone and indanone oximes with LDA
at -78 oC, using trimethyl chlorosilane as electrophiles. O-TBS-alpha-tetralone
and 6-methoxy substituted oximes derivate, were also prepared and their
silylation gave different substituted silylated products with expected
molecular weight. The alkylation of alpha tetralone with benzyl
bromide was obtain in good conversion, but the product is unstable.
Morales,
Victor M.; Morales, Angel L. Chemistry Department, UPR-Rio
Piedras - Van Keuls, Fred.
Chemisorption
and chemical characterization of monolayers at barium strontium titanate
Ba0.5Sr0.5tio3 (BSTO) for phase shifter applications
Nuñez,
Daliangelis; Delgado, Dana; Torres, Ivelisse; Rosario, Osvaldo.
Chemistry Department, UPR
Method
development for the determination of suspected endocrine disrupting
compounds (EDCs) in seawater
The
determination of pollutants in seawater is an area that has not been well
studied in environmental sciences. Cases of endocrine disruption in
marine species are known and its ecological significance has been
discussed. There is a need to know the levels of Endocrine
Disrupting Chemicals (EDCs) in the coasts of
Ortíz,
Taymaliz; Cruz, Heidyleen; Carballeira, Néstor M.
Chemistry, UPR
Analysis
of lipids as marine biomarkers in La Parguera, Lajas, in the South of
Puerto Rico
Sediment
cores collected at La Parguera,
Quiñones,
Alejandro; Lewis, Ariel. Química, UPR Mayagüez -
León, Ruth G.; Cadilla, Carmen. Bioquímica, UPR Ciencias Médicas
- López-Garriga, Juan. Química, UPR Mayagüez.
Protein
expression and purification of the Hbi Phe(B10)-Tyr mutant
Quiñones,
Luis; Guevárez, Edward; Morales, Reginald. Natural
Sciences, Chemistry Department, UPR Río Piedras - Quesada,
Orestes. General Studies, Physical Sciences, UPR Río Piedras.
Phospholipase
A2-Concanavalin A conjugate as a probe for PLA-binding protein in human
erythrocyte
In
an effort to direct the Naja nigricollis phospholipase A2 (PLA2) toward
specific regions of the human erythrocyte membrane surface this enzyme was
covalently coupled to Concanavalin A (Con A). Our results point to
the possibility that the A. halys PLA2 may be interacting with a specific
protein on the erythrocyte surface. In order to get more evidence in
favor of a PLA-binding protein hypothesis, two heterobifunctional
reagents, succinimidyl-3-(2-pyridyldithio) propionate (SPDP) and
succinimidyl trans-4- (maleimidylmethyl) cyclohexane-1-carboxylate (SMCC),
were used respectively, to modify the lysine residues of Naja nigricollis
basic PLA2 to thiols and to add thiol reactive maleimide groups to
Concanavalin A. After deprotection of the thiolated protein
the two modified protein were reacted to each other forming a stable
thioether bond between them. Subsequent PLA2-Con A was achieve by
affinity chromatography and ultrafiltration. PLA2-Con A shown
both hydrolytic and agglutinin activity. Assay with the N. nigricollis
PLA2-Con A conjugate shown difference in the fatty acids species
hydrolyzed by the native enzyme. The similarity of the composition of
fatty acids hydrolyzed by the Lectin-PLA2 conjugates and A. halys PLA2
suggest that both are due to lipid interactions at membrane protein-lipid
interface. (Supported by NIH grant R25GM6115)
Restituyo,
Jannelly; Carballeira, Néstor M. Chemistry
Department, UPR
A
new approach to the enantiomeric resolution of (±)-2-methoxytetradecanoic
acid, an antifungual compound
The
compound (±)-2-methoxytetradecanoic acid (1) was first isolated from
Rivera,
Jessica; Nieves, Ileana; Oyola, Rolando; García, Carmelo; Piñero,
Luis; Cruz, Nadya. Department of Chemistry, UPR Humacao.
Formation
of oxidation intermediates of promazine derivatives as a function of
organic solvent and water ratio
Promazine
tricyclic drugs are relevant in the treatment of depression and
schizophrenia. Although these drugs are efficient in the treatment
of these conditions, they also produce severe phototoxic side effects on
patients. The side effects have been related to the oxidation
intermediates formed that depend on the molecular structure of the
promazine derivatives. Some mechanisms have been postulated that
involve electron transfer intermediates forming cation and dication
radicals in a given environment. The samples are titrated with a known
amount of solvent to reach the desired solvent ratio. Cyclic and
Differential Pulse Voltammetry experiments varying the water : methanol
ratio showed that the oxidation ability of the promazine derivatives
increases with concentration of water. This may result from the
stabilization of the cation radical formed by protonation and further
chemical reaction in the presence of water. In addition, the number of
electrochemically produced intermediates decreases in water attributed to
this stabilization or chemical reaction.. These results will be
correlated with the photoelectron transfer mechanism response of these
drugs that are relevant in the understanding of the causes of side effects
observed in patients that will aid in the formulation of new and more
efficient new drugs. Sponsored by Advance, NSF (SBE-0123645),
UPR-Humacao and AMP, UPR.
Rivera,
Catherine; Rivera, Jose; Gubala, Vladimir. Department of
Chemistry,
Synthesis
and self-assembling properties of 8-aryl-guanosine analogues
Rivera,
Maria del Carmen; Torres, Gerardo; Prieto, Jose A. Quimica,
UPR-Rio Piedras.
Microwave
assisted epoxidation of homoallylic alcohols: studies toward the
construction of polypropionates
Polypropionates
consist of an array of consecutive stereogenic centers containing
alternating hydroxyl and methyl groups. This is a common feature in
many biological active molecules. The manipulation of the
stereochemistry of all chiral centers in the polypropionate unit is very
challenging. We have developed an epoxide chemistry were the
stereochemical control is based on the stereoselectivity of the
epoxidation and the cis/trans geometry of the alkene. The use of
microwave irradiation has allowed us to accelerate the epoxidation
reaction of different homoallylic alcohols if compared to conventional
heating. The Sharpless transition metal catalyzed epoxidation using
VO(acac)2 was used to study the diastereoselectivity (syn:anti) of the
epoxidation of different homoallylic alcohols under microwave
irradiation. We also studied the diastereoselectivity of the
epoxidation using m-CPBA when the alcohol is protected with different
protecting groups. The results of these studies will be presented.
Work supported by NIH SCORE (250GGM-08102-29) and NIH RISE
(IR25-GM-61151-01A1).
Rivera,
Raquel. Chemistry, UPR Rio Piedras - Morales, Ricardo.
Physical Sciences, UPR Rio Piedras – Rosario, Osvaldo.
Chemistry, UPR
Quantitative
study of Tropical submicrom aerosols using Thermal Desorption/Gas
Chromatography/Mass Spectrometry
Natural
and anthropogenic atmospheric aerosols play an important role in climate
forcing, directly by scattering and absorbing solar radiation, and
indirectly by modifying cloud optical properties through their ability to
act as cloud condensation nuclei (CCN). Recent studies in the
assessment of how aerosols influence global climate pointed out the role
that the organic component of aerosols play in climate forcing as the most
uncertain of the variables accounted (IPCC, 2001)[i]. Aerosols are
short life species in the atmosphere, thus chemical and physical
characterization of aerosols at different geographic locations and
seasonal conditions is needed to quantify their role on a global scale.
Detailed chemical characterization using Thermal Desorption / Gas
Chromatography / Mass Spectrometry (TD/GC/MS) of submicron (DP < 0.6 µm)
organic aerosols, sampled with a Lundgren Cascade Impactor, in the island
of Puerto Rico and around the Caribbean has been performed. The use
of specific compounds associated to certain sources was used as an
indicator of the origin of the sampled aerosols. The proposed work
is based on a quantitative comparison of the organic composition of these
tropical submicron organic aerosols, sampled on different locations in
Rivera
Gonzalez, Gustavo J.; Primera Pedrozo, Oliva M.; Hernández-Rivera,
Samuel P. Center for Chemical Sensors Development for
Explosives, Department of Chemistry,
FT–IR
acoplado a fibras opticas para la detección de residuos de ácido
acetilsalicílico en reactores farmacéuticos
Un paso importante en los procesos farmacéuticos consiste, en la remoción de los residuos de drogas en el área y equipo envueltos. Las industrias farmacéuticas enfrentan un problema con la validación de las superficies que entran en contacto con los ingredientes activos farmacéuticos (API). Los procedimientos utilizados para limpiar los residuos de drogas deben validados de acuerdo a las buenas prácticas y reglas de manufactura. En esta investigación se informa la detección de aspirina (ácido acetilsalicílico) en superficies metálicas usando Espectroscopia Infrarroja de Transformada de Fourier (FT–IR) acoplado a fibras ópticas. Los cables de fibras ópticas que transmiten en el intervalo conocido como infrarrojo central (Mid-IR) han hecho posible desarrollar una variedad de sondas espectroscópicas para análisis in situ. En nuestro estudio se utilizó un diseño de sonda que opera en el ángulo de rozamiento para detectar y cuantificar niveles de concentraciones superficiales varios g/cm2 de aspirina en acero inoxidable. Las curvas de calibración se obtuvieron usando placas de acero inoxidable de 6 pulgadas de largo por 3 pulgadas de ancho. Lan muestras se prepararon disolviendo el ácido acetilsalicílico en metanol y en una mezcla metanol – agua 50:50 (pp). Las muestras se depositaron en las placas usando el método de “smearing” hasta obtener concentraciones superficiales en el rango de 0.5 a 20 g/cm2. Los datos se analizaron utilizando rutinas de Chemometrics”. Se compararon los límites de detección obtenidos de las curvas de calibración utilizando metanol y mezclas de metanol y agua. Palabras claves: fibra óptica, ángulo de rozamiento, ácido acetilsalicílico, Chemometrics.
Rodriguez,
Kristy; Souto, Fernando; Rodriguez, Lolita; Justicia, Shandra D.;
Velez, Gisselle A. Departamento de Quimica, UPR-Mayagüez
Rubia
tinctorum L. por HPLC: Analisis de raiz molida de planta madura
Esta
investigación se basa en el estudio de la raíz molida de planta madura
de Rubia tinctorum L., planta
medicinal utilizada para combatir cálculos renales. La raíz de esta
planta es el órgano que contiene los compuestos
activos de la misma, como se cree son la lucidina (R1= OH, R2 =
CH2OH, R3= OH, R4= H, R5= H ), alizarina (R1= OH, R2 = OH, R3= n
H,
R4= H, R5= H) y purpurina (R1= OH, R2 = OH, R3= H, R4= H, R5=
H ) en forma de los correspondientes glicósidos, como ácido ruberítrico
(R1= OH, R2 = CH2OH, R3= o-Primeversoido, R4= H, R5= H ) glicósido de
alizarina. El objetivo principal de esta investigación es separar e
identificar los componentes en la Rubia comercial mediante la técnica de
separación cromatográfica “High Preformance Liquid Chromatography (HPLC).
Se utilizó la columna Alltima C18 para lograr la separación de estos
compuestos utilizando condiciones con métodos programados para gradiente
e isocrático. Se utilizó como disolvente agua (pH=7) y acetonitrilo en
varias proporciones modificadas según las condiciones establecidas en la
literatura . La muestra se preparó mediante la técnica de extracción
Soxhlet, utilizando 5.000gr de “madder” en 125.0 mL de agua triple
destilada. El extracto puro se fraccionó por filtración gel con Sephadex®
G-25 fino, en una columna cromatográfica (r=1.25 cm, L=95.0 cm). Las
fracciones se analizaron por HPLC, logrando aislar muestras puras e
identificar los componentes aislados (UV-Vis). Las fracciones con
componentes puros se combinaron y se preservaron por ultracongelación
para más tarde ser estudiadas y sometidas a pruebas de actividad antilítica
con el electrodo selectivo de Calcio (Ca+2). Esto permitirá en un futuro
determinar la bioactividad de estos componentes.
Rodríguez,
Marilyn; Nieves, Maribel; Méndez, Nancy I. Química-Física,
U.P.R. Arecibo.
Medición
de parámetros físico – químicos y determinación de materiales orgánicos
semivolátiles en aguas superficiales del Caño Tiburones
Rosario,
Medardo; Rivera, José. Department of Chemistry,
Synthesis
of dendronized-carboxylic acids for peptide derivatization
The
initial steps towards the synthesis of a dendronized peptide are
described. Methallyl dichloride is used as monomeric building block for
the synthesis of dendronized carboxylic acids. Such dendronized carboxylic
acids are will be used for the derivatization of a small library of
peptides. The required peptides will be prepared using standard Fmoc solid
support synthetic methodology. The resulting dendrimers will be used as
multi-functional probes to visualize cellular processes.
Ruiz,
Mariangel. Chemical Engineering, UPR-Mayagüez -
Rivera, Luis A. Chemistry, UPR-Mayagüez.
Design,
synthesis and characterization of 1-alkyl-2-methylbenzimidazoles by phase
transfer catalysis and comparison with corresponding homogeneous reaction
The
title compounds have been prepared by phase transfer catalyzed alkylation
of 2-methylbenzimidazole using tetra-n-butylammonium bromide as catalyst
without solvent and at room temperature. Previous reports by other
researchers for the phase transfer catalyzed reaction have used different
reaction partners and reaction conditions than in our laboratory. A
description of the nature of catalyst, solvent, reaction conditions
(temperature and reaction time), purification protocols, and a critical
comparison with the homogeneous reaction with emphasis on the advantages
and disadvantages of each will be presented. The reaction products
were analyzed by GC-MS and characterized by proton nuclear magnetic
resonance and FT-IR spectroscopies.
Sanchez-Baez,
Eliany. Chemistry,
Directed
evolution of TLR2
Toll-like
receptor 2 (TLR2) is a transmembrane protein that is part of the
immunological response of our body against pathogens. Expression of the
extracellular domain of TLR2 in Escherichia coli results in aggregated
protein that cannot be refolded or purified by conventional methods. Green
fluorescent protein (GFP) can be used as a reporter to track the correct
folding and solubility of the protein fused to it. Using random
mutagenesis, we want to evolve TLR2 into a soluble protein. The TLR2/GFP
gene was first amplified using error-prone PCR reactions. The DNA produced
was digested, ligated, and transformed. The DNA was introduced to E. coli
cells using the vectors pBAD/GFP and pUC19/GFP. Then, the colonies were
exposed to UV light to detect visually if they were glowing. After the
screening of the colonies, just one glowing colony was found. The plasmid
was analyzed and sequenced and found to have TLR2 fortuitously deleted.
Sánchez-Cortés,
Juan-José; Carrasquillo, J.; Feng, M.; Alejandro, F.
Chemistry Department, University of Puerto Rico, Río Piedras
- Gonzalez, F. University of Puerto Rico, Medical
Sciences Campus - Guadalupe, A. R. Chemistry Department,
University of Puerto Rico, Río Piedras.
Electrochemical
studies of binding of poly-[Fe(4-vinyl-4’methyl-2,2’-bipyridine)3]Cl2
to calf thymus
Fe(vbpy)3]Cl2
(vbpy = 4-vinyl-4’-methyl-2,2’-bipyridine) was synthesized reacting
FeCl2.4H2O with vbpy in H2O in a 1:3 molar ratio and recovered by
precipitation in ether. The complex was characterized with FT-IR and
1HNMR. Cyclic voltammetry (CV) was employed to characterize the
electrochemical behavior of the complex at a glassy carbon electrode.
Poly-[Fe(vbpy)3]Cl2 was synthesized by radical polymerization of
[Fe(vbpy)3]Cl2 heating at 65oC for 48 hours in a vacuum sealed ampoule.
Chloroform and azobisisobutyronitrile (AIBN) were used as solvent and
initiator, respectively. This material was characterized by 1HNMR and FT-IR;
both spectra were compared with the monomer ones to verify the
polymerization. The molecular weight of the polymer was determined through
HPLC-SEC analysis with DMF as the mobile phase using Poly
(4-vinylpyridine) standards for molecular weight calibration. Binding
constant (Kint) and binding occupancy (n) between the polymer and Calf
Thymus DNA (ctDNA) were determined by electrochemical titrations. This
worked showed that Poly-[Fe(vbpy)3]Cl2 is an effective DNA carrier as well
as a potential probe for electrochemical DNA detection.
Suárez,
Christian; Sanabria, David; Cruz, Clarisa; Carballeira, Néstor.
Chemistry, UPR
Synthesis
of new antifungal acetylenic fatty acids
Antifungal
bioassay isolation of the ethanol extract of the roots of a Peruvian
plant, Pentagonia gigantifolia yielded 6-octadecynoic acid (1) and the new
6-nonadecynoic acid (2). These compounds inhibited the growth of
fluconazole-susceptible and resistant Candida albicans strains.
Candida albicans a component of the normal human microflora, is the most
common cause of fungal infections. Their antifungal potencies were
comparable to those of amphotericin B and fluconazole. Candida
albicans a component of the normal human microflora, is the most common
cause of fungal infections. To our knowledge we are unaware of any
paper describing the synthesis of compound (2). We want to
synthesize this fatty acid because it has great antifungal activity and we
want to compare it with the natural compound. The synthesis will be
starting from commercially available (trimethylsilyl) acetylene.
This four step synthesis will be presented.
Torres,
Mayda; Raptis, Raphael; Yang, Guang. Chemistry Department,
The
structures of Zinc (II) pyrazolates
The
structures of Zinc (II) pyrazolates could be very sensitive to anions
and/or substituents on the pyrazole ring. By using different Zinc
salts and different substituted pyrazoles, we expect to prepare Zinc
pyrazolates with different structures. By reacting 3-phenyl pyrazole
with Zn(CLO4)2 .6H2O in 95% EtOH we obtain a Zinc pyrazole complex,
Zn(3-phpzH)4 (CLO4)2, which has been characterized by x-ray diffraction.
Because the pyrazole acts as a monodentate ligand, in this complex the
Zinc is coordinated by four pyrazole ligands. We are now trying to
use this Zinc complex as precursor to prepare Zinc pyrazolates. Also
we are using 4-pyridyl pyrazole to prepare new compounds.
Torres
Torres, Mirayda. Horticultura, UPR Mayagüez -
Beltran Melendez, Carmen M.; Rodriguez, Prof. Lolita; Souto, Dr.
Fernando. Quimica, UPR Mayagüez.
Bioproduccion
de hidroxiantraquinonas en Rubia tinctorum L. cultivada in vitro
Rubbia
tinctorum L. es una planta de la familia Rubiáceae utilizada
medicinalmente por poseer muchas propiedades curativas, en especial porque
ayuda en la disolvencia de los cálculos renales. La parte más utilizada
de la planta es la raíz, ya que es aqui donde se produce hetérosidos de
hidroxiantraquinonas. Estos compuestos son los que se cree
caracterizan las propiedades curativas de la Rubia. En esta investigacón
buscamos estudiar rangos específicos de las concentraciones hormonales
para su micropropagación, estimulación de una producción optima de raíces,
inducción de la acumulación de los derivados de alizarina en la raíz y
la eliminación de la biosíntesis de los compuestos derivados de lucidina.
Según estudios carciogénicos con animales (ratas y conejos) han indicado
que los compuestos derivados de lucidina tiene una alta toxicidad (mutagénico
y genotóxico). En este estudio in vitro con R. tinctorum L., hemos
trabajado con diferentes concentraciones de reguladores de crecimiento en
medio semisólido (agar) con sales de Murashigue & Skoog (MS)
para observar el crecimiento, producción de ramificaciones, hojas, callos
y raíces. Los reguladores de crecimiento utilizados han sido la
citoquinina kinetina (0.5ppm-8.0ppm) y la auxina ácido indolacético
(IAA, 0.5ppm-3.0ppm) en combinación (matriz). Comenzamos produciendo
tejido vegetal subcultivando nudos de R. tinctorum en un medio MS líquido
libre de hormonas. Luego tomamos explantos de este subcultivo para
introducirlos a medios MS sólidos con combinaciones diferentes de
concentración de reguladores de crecimiento. Este cultivo estuvo bajo
observación por un período de ocho semanas. Con los resultados obtenidos,
hemos encontrado las condiciónes hormonales para una alta producción de
ramificaciones, hojas y raíces. Los resultados serán presentados
en la conferencia. Nuestro próximo trabajo será, estudiar la composición
de las raíces para cada concentración hormonal.
Actividad
antilítica de Baquiña (L. peltatum)
Lepianthes
peltatum (L.) es una planta medicinal utilizada tradicionalmente bajo el
nombre de Baquiña hembra para tratar los cálculos renales y otras
calcificaciones compuestas fundamentalmente de oxalato y fosfato de calcio.
Decocciones de Baquiña preparadas en el laboratorio demustran que la
planta es capaz de formas complejos robustos con sales de calcio solubles
y disolver las sales insolubles de oxalato y fosfato de calcio. Por medio
de un análisis de GC/MS del extracto orgánico liposoluble, se encontró
que en esta fracción el componente mayoritario de la Baquiña es el
4-nerolidilcatecol (4-NC(OH2)). El acomplejamiento de calcio que presenta
la planta se le ha adjudicado preliminarmente a este componente, aunque no
se encuentra en el extracto acuoso de la planta pues es virtualmente
insoluble en agua. Se cree que el agente acomplejante es un dimero del
4-nerolidilcatecol que es soluble en agua. El propósito de nuestra
investigación actual es determinar la capacidad del 4-nerolidilcatecol de
formar complejos con calcio como evidencia de su actividad antilítica. A
fin de entender mejor su comportamiento hemos realizado estudios de la
formación de complejos con calcio usando como modelo el agente
complejante: EDTA y la complexona (o-cresoftaleína). Hemos utilizado el
electrodo selectivo de calcio Hach para estudiar ambos y proximamente
haremos lo mismo con el nerolidilcatecol, los extractos acuosos y sus
fracciones. Los estudios modelos han permitido verificar el funcionamiento
del electrodo, definir su respuesta en los distintos medios acuosos en
función del pH y la presencia de amortiguadores y caracterizar y conocer
los límites de detección de los electrodos. Tenemos resultados inéditos
obtenidos con la o-cresoftaleína complexona que demuestran que
efectivamente tiene la capacidad de acomplejar, primero, un ión de calcio
y luego otro. Los datos obtenidos permiten estimar las constantes de
acomplejamiento de ambos compuestos y comprobar la efectividad del
electrodo, lo que permitirá estudiar las distintas formas del catecol
presentes en la planta.
Velez-Camacho,
Yahaira. Department of Chemistry,
C22G-Tat
mutation down regulation of LTR activity and cytokine gene expression
The
human immunodeficiency virus (HIV) Tat activator protein is a pleitropic
factor that regulates both viral and host gene expression. At the
HIV promoter, Tat protein is required for LTR (Long Terminal Repeat)
activity. Previous studies showed that the C22G mutation on
Tat protein down regulates the LTR activity, but we are interested in the
effect. To study the effect of this mutation a Tat C22G mutant was
cloned into a expression vector, and sequenced. The PCR technique
was used to amplify the mutant Tat. This clone will provide a tool to use
to produce Tat C22G protein in E.coli cells. The purified mutant
protein can be used to treat mammalian cells to test the effect on
cytokines expressionThis investigation was supported by NIH RLK NRSA
GM07732 from the Pontificia Universidad Católica de Puerto Rico, MARC
U*STAR Honor Program."