AROCHO-PÉREZ, FREDDIE; Díaz-Vázquez, Liz M.; Rosario, Osvaldo, UPR-RÍO PIEDRAS, Natural Sciences, Department of Chemistry
Sebum: A potentially Important Matrix for the Determination of Human Exposures to Environmental Pollutants

Sebum has been used to monitor use of controlled drugs as well as exposure to dioxins. Based on this, it is logical to extrapolate its use to also monitor exposure to other environmental pollutants. We have been working on the development of methodology for the sampling extraction and analysis of organic compounds in sebum. Commercially available sebum has been used for the method development. We have tested the use of patches, cotton swabs and cotton balls for the direct sampling of sebum from different persons. A range of solvents and solvent mixtures were tested to optimize extraction of analytes spiked onto sebum. The results of these experiments will be presented. We are planning experiments to determine limits of detection and linearity in the methodology.

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AYALA, NORMA; Cruz, Heidylee; Carballeira, Nestor M., UPR-RÍO PIEDRAS, Natural Sciences, Department of Chemistry
Identification and Total Synthesis of the Novel 13-Methyleicosanoic Acid from the Caribbean Sponge Ircinia felix

The phospholipid fatty acid composition of the sponge Ircinia felix was revisited and 57 different fatty acids were identified, including the novel 13-methyleicosanoic acid which has no literature precedence. The fatty acid chain lengths in this sponge ranged between 12 and 25 carbons, and a variety of structural types were identified. Structural characterization was accomplished using gas chromatography – mass spectrometry on their corresponding methyl esters and pyrrolidide derivatives. The characteristic fatty acid in the sponge was the 23-methyl-5,9-tetracosadienoic acid, while the most interesting series of fatty acids was a family of methyl-branched fatty acids with the methyl group at positions 11, 13, 14, 15 and 16. The structure of the novel 13-methyleicosanoic acid was confirmed by total synthesis. The identification and total synthesis of the novel fatty acid will be presented.
(Norma Ayala thanks the Howard Hughes program for an undergraduate fellowship)

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BELLO, SHEILA, UIA-BAYAMON, Biotechnology; Rivera Montalvo; Luis A., Prof., UPR-MAYAGÜEZ, Arts & Sciences, Department of Chemistry
Alternate Wittig Route to the Synthesis and Photophysical Properties of 9-(benzothiazolylmethylidene) fluorene

The alternate synthetic sequence for the preparation of the title compound was explored starting with the cyclocondensation of 2-aminothiophenol under acid catalysis to yield the 2-benzothiazolylmethanol. The second step involves the oxidation of this heterocyclic alcohol to obtain the 2-benzothiazolecarboxaldehyde. The final step incorporates the use of the Wittig olefination, using different reacting aldehyde and phosphonium salt partners from those reported by Ms. Susana Vargas and Dr. Luis A. Rivera, to yield the heterocyclic fluorene target compound. The two synthetic strategies will be compared with emphasis on the purity and yield of the reaction products. In addition, results from the photophysical studies in aqueous micellar solution will be presented.

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BETANCOURT, JOSÉ E.; Cruz, Clarisa; Carballeira, Néstor, Prof., UPR-RÍO PIEDRAS, Natural Sciences, Chemistry Department
Synthesis of New Acetylenic Fatty Acids as Potential Topoisomerase I Inhibitors

The design of small molecules that bind to deoxyribonucleic acid (DNA) and its topoisomerases I and II is an interesting area of investigation. Topoisomerase I inhibitors constitute a family of antitumoral agents that can be used in the battle against cancer. One way of Topoisomerase I inhibition is DNA binding. Other inhibitors act by preventing the DNA-topoisomerase I complex formation, and some of these are natural products that can be interacting directly with the enzyme. Recent studies have identified DNA topoisomerases as reaction targets of various antineoplastic drugs. For example, the 9-octadecynoic acid is an acetylenic fatty acid isolated from Schoepfia californica that exhibited cytotoxic potential towards KB cells and is also capable of DNA binding. This acid does not possess any structural characteristics of known molecules that bind to DNA. Therefore, its mode of interaction with DNA seems to be unprecedented. We have undertaken the total synthesis of a series of acetylenic fatty acids, such as the unknown 4,8-pentadecadiynoic and 5,9-hexadecadiynoic acids in order to test their potential as new DNA topoisomerase I inhibitors. Our recent progress in this area will be presented.

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BURGOS, JOHANNA; Estévez, Carlos O;.; González, Isadora Z.; Rodríguez, Lorna; Vega, Dimara; Vega, Valerie; Estévez, Juan G., Prof., UPR-CAYEY, Department of Chemistry
Computational Investigation in undergraduate Chemistry: A Learning Resource for Students

Statistics and daily experience show that every day the number of science students is decreasing. The purpose would be directed towards the better preparation of the students, the increase their self esteem and the retention of a population that is more disposed to change their area of study. A project in undergraduate investigation in computational chemistry has been developed. This area has been selected due to: its low cost, the availability of infrastructure, it allows an insertion of information technology, it provides for the difficult learning process and the incursion in a wide variety of fundamental chemistry subjects.
In their project the student is taught the use of simple research techniques, traditional and online, data entry, computer program management, data analysis, data publication (in State, National and International Congresses), group work, social activities and knowledge of academic and socio-economic realities outside of the student’s immediate surroundings.
The investigation topics are: original, they cover the areas of General Chemistry, Organic Chemistry (especially the areas pertaining to molecular and electronic structure), relative stability, the effects of substituents groups and Hydrogen bonding. Very few investigations have incurred in the area of inorganic species.
The students who enter the group are selected by non-traditional methods: they are observed in the classroom, they are interviewed. Their GPA is not a factor in their acceptance. The subgroups are interdisciplinary and are formed by two or four students. These subgroups do not have the opportunity to select the topic of their work, although the project does allow for the selection of a topic by students who have been in the project one or two years and who have consulted with professors from other university campuses.
The implementation of the project faces difficulties, which can be classified as: administrative, academic and personal.
The achievements in the process which has been undertaken with students demonstrates: in the majority of cases an improvement in attitudes towards science, an adequate comprehension of the processes undertaken in the scientific method and high retention. Also, an improvement in the attitudes towards group work and in the acceptance of personal and individual differences was noted and access to greater opportunities for the realization of other investigations in high quality research centers and a positive attitude towards postgraduate studies were achieved.

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CLASS ESTÉVEZ, JOSÉ; Bosques, Carlos, UPR-MAYAGÜEZ, Arts and Sciences, Department of Chemistry; Imperiali, Barbara, Prof., Massachusetts Institute of Technology
Probing the structural effects of the alpha-1,6-fucosylation to the proximal N-Acetylglucosamine in N-linked glycoprotein

Glycoproteins play diverse essential roles in a wide variety of biological systems. It has been shown that the carbohydrate moieties of these conjugates are important for events such as protein folding and cellular recognition. Previous studies from our laboratory have demonstrated the relationship between the attached saccharide chains and the secondary structure of the peptide. Other very important events in these glycosylation pathways are the post-translational modifications of the carbohydrate moieties such as the incorporation of a fucose saccharide to the chitobiose core. Although over expression of fucosylated glycoproteins have been observed in cancer cells and other cellular conditions no direct structural relation between the fucosylation and the peptide structure has been studied. In order to improve the understanding of the structural effects of the fucose on the peptide backbone. We have used human interferon-beta as our model. X-ray crystallography of the molecule shows a single glycosylation consisting of a biantennary complex-type carbohydrate chain containing a beta-D-GlcNAc(1-4)-[alpha-L-Fuc-(1-6)]-D-GlcNAc trisaccharide core. This crystallographic data suggest that an Asn in position 86 might be interacting with the fucose. To study such interactions our approach was to synthesize an unglycosylated peptide, a chitobiose-glycosylated peptide lacking the f

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COLÓN, FRISIA, UPR-MAYAGÜEZ, Arts & Sciences, Chemical Engineering; Crespo, Gisela; Cortés Figueroa, José, Prof., UPR-MAYAGÜEZ, Deparment of Chemistry
Determination of Fullerene Basicity by Chemical Kinetics

The basicity of buckminsterfullere was estimated from the competition ratios of fullerene, piperidine, and phosphines toward the organometallic fragment W(CO)5. The results indicate that fullerene is a good pi-acid and a good Lewis base(relative to known Lewis bases such as phosphines and phosphites). This basicity is surprising in view of the high electron gain tendency of C60 and higher fullerenes.
Acknowledgments: This work was supported by the donors of The petroleum research fund, administered by the American Chemical Society, the National Science Foundation, and PR-LSAMP.

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COLÓN, MARISOL; Antoun, Helena; Solá-Soto, Hilda; Rosario, Osvaldo, Prof., UPR-RÍO PIEDRAS, Natural Sciences, Department of Chemistry
Method Development for the Analysis of Organic Compounds on Suspended Particles of an Aquatic System

The environmental impact of organic pollutants in aquatic environmental has greater importance in today’s world than ever before. Even though much work has been done in the analysis of organic chemicals in such environments, the distribution, transport and ultimate fate of these compounds is still not completely understood. To better understand the process, it is necessary to detect pollutants, at the ppb and ppt range, in the different compartments that constitute the system. Some of the compartments of interest are the water column, the suspended particles and the sediments. Since organic compounds have different chemicals and physical properties, they interact in different ways with the components of the aquatic system.
In the first stage of this research, we are optimizing the analysis methods that will be used for the detection of organic pollutants, in a three phase aquatic system. At this time, we are working in the extraction methods for suspended particles and water. To simulate suspended particles, silica is used as the model matrix. Ultrasonic extraction with a mixture of solvents in being used as the extraction method followed by filtration through a GF/F filter and preconcentrated to 1 ml with nitrogen gas. The method for suspended particles has been evaluated in terms of solvents used for the extraction, volume, and extraction time. Gas Chromathography-Mass Spectrometry performs the analysis. We are now in the process of determining the linear range and lowering the detection limit.

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COLÓN, YLEANA M.; Hernández, Neiza; Hernández, Samuel; Mina, Nairmen, Prof., UPR-MAYAGÜEZ, Arts & Sciences, Department of Chemistry
Ion Mobility Spectrometry Determination of Smokeless Powder

Federal agencies are interested in detecting explosive devices and compounds potentially energetic or toxic to humans and animals. Advanced equipment has been designed and used to achieve this goal. Ion mobility Spectrometry (IMS) is a leader technique in explosive detection. In this project diluted standard solutions acquired from Radiant International, Analytical Materials, Austin TX were used to developed an analytical methodology to detect RDX, PETN, black powders, smokeless powders, nitrocellulose, and potentially other substances with the Barringer IonScan 400. In addition, Ion Mobility Spectrometry is being used to measure the limits of detection of these energetic substances. It was found in this project that IMS can detect smokeless powder in the order of a few nanograms.

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CRESPO, RUBÉN; Castellanos, Ingrid J.; Cruz, Gloydian; Griebenow, Kai, Prof., UPR-RÍO PIEDRAS, Natural Sciences, Department of Chemistry
Encapsulation-Induced Aggregation and Loss in Activity of G-chymotrypsin and their Prevention

Sustained release from a biodegradable polymer is a remarkable technology for the delivery of proteins. For example, it will enable replacing daily painful injections of protein drugs. The solid-in-oil-in-water (s/o/w) encapsulation technique was used with the objective of encapsulating g-chymotrypsin in biocompatible poly(DL-lactide-co-glycolide) (PLG) microspheres. This technique was employed because the protein is not exposed to a water/organic interface, which it is known to denature proteins. Before encapsulation in PLG, the samples were lyophilized, some containing polyethylene glycol (PEG) added to establish a 1:4 ratio of protein-to-excipient (w/w). The encapsulation efficiency improved with the addition of PEG to 72%, compared to the sample without any excipient (55%). During the process of encapsulation the enzyme was found to non-covalently aggregate (34%). The amount of aggregates decreased significantly when PEG was used as an excipient to 8%. Activity experiments revealed that the specific activity of enzyme released within 24h was reduced to ca. 50% after encapsulation without stabilizing excipient, while co-lyophilization with PEG led to only 8% of reduction in the specific activity. It was evident that the encapsulation with PEG prevented the encapsulation-induced aggregation, and loss in activity.

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CRUZ, OSVALDO, UPR-MAYAGÜEZ, Ciencias y Artes, Biotecnología Industrial; Rodríguez, Lolita; Souto, Fernando, Prof., UPR-MAYAGÜEZ, Departamento de Química
Aislación y estudio de la actividad antilitica y capacidad de complejar calcio del 4-nerolidilcatecol

El 4-nerolidilcatecol, componente químico mayoritario de la Lepianthes peltatum (Baquiña), fue aislado a partir de fracciones obtenidas mediante extracción Soxhlet con C6H12 o C6H14 de hojas molidas y liofilizadas de L. peltatum silvestre. Experimentos anteriores con alícuotas de 0.2ml de extracciones realizadas en CH2CL2 indicaron, por GC/MS, estar constituidos principalmente dos compuestos identificados como ß-cariofileno y 4-nerolidilcatecol según sus respectivos espectros de masa. Análisis de estos mismos extractos por cromatografia de capa fina (TLC) en fase normal reveló la presencia de otros componentes. Se procedió entonces a purificacion del 4-nerolidilcatecol mediante cromatografia líquida de columna. Las fracciones recolectadas de la columna fueron analizadas por TLC en fase normal. La presencia del 4-nerolidilcatecol se determinó mediante el tratamiento de las placas cromatográficas con el reactivo de vainillina-acido sulfúrico. Una vez identificadas las fracciones correspondientes al 4-nerolidilcatecol, éstas fueron recolectadas y analizadas por HPLC y NMR encontrando el compuesto analiticamente puro.
Además del aislamiento del 4-nerolidilcatecol se estudiara la actividad antilitica de este compuesto y su capacidad para acomplejar calcio en funcion del pH. Esto con el fin de determinar si el 4-nerolidilcatecol podrirá ser utilizado en el tratamiento de piedras en el riñon.


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DÍAZ, AGUSTÍN; Mitk’El, B. Santiago; Guadalupe, Ana R., Prof.; Colón, Jorge L., Prof., UPR-RÍO PIEDRAS, Natural Sciences Faculty, Department of Chemistry
Synthesis and preparation of Zirconium Phosphates and Phosphonates used in the preparation of Biosensors

We are interested in the construction of electrochemical biosensors using zirconium phosphates or phosphonates inorganic solids. Zirconium phosphates or phosphonates are acidic, inorganic, ion exchangers with layered structures, which have been extensively investigated. Changing phosphonate groups we can intercalate compounds in order to construct many new materials, as well as biosensors. The heterogeneous interlayer microenvironment can have profound effects on the rate of chemical reactions occurring within the solid. We are using bis(1,10-phenanthroline-5,6-dione)bipyridine ruthenium(II) ([Ru(phend)2(bpy)]2+) as the inorganic complex in our layers. This complex has been previously used in the preparation of biosensors, but we are using it for the first time in this more rigid environment. This presentation includes the preparation and characterization of these materials.

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ESTÉVEZ, CARLOS O.; Ortiz, Debra M.; Ramos, Emanuel E.; Estévez, Juan G., Prof., UPR-CAYEY, Department of Chemistry
Computational Study, Through the Semiempirical Method AM1, the Effect that the Substituents Positions in the R1 and R2 monomer of 2-Ureido-4-[1H]- pyrimidinone on the Formation of Hydrogen Bonds.

Extensively it has been recognized the important role that play the links of hydrogen bonds in the formation of molecular species that they represent that type of interaction. Examples of these are the interactions in the DNA. Molecular species that interact by means of four Hydrogen bonds have been recently reported. In spite of the fact that it has been extensively studied as much theoretically as experimentally, little has been reported upon the effect of substituents in the monomer on the formation of the dimer. This research presents (with the purpose of finding the biggest interaction) the effect of the substituents groups -C6H5, -CH3, -NO2 in the R1 and R2 positions of the monomer 2-Ureido-4[1H] - pyrimidinone.
For it, semiempirical calculations were carried out by means of the method AM1 for the monomer as well as for the dimer. Initially all the molecular species were considered to be planar and its molecular geometries were optimized.
The results show a growing tendency in the association energy at R2 order: - CH3 < -C6H5 < -NO2 y R1: -C6H5 > -CH3 > -NO2. In summary the interaction energy is maximum for a species in which R1, is a group attractor of electrons and R2 a donor of electrons. The values of the association energy fluctuate among –19.407 kcal/mol for the substitutes R1=. -CH3, R2 = -NO2 to –25.327 kcal/mol for R1 = -NO2 and R2 = -C6H5.

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FELICIANO OLAF; Brito, Rosa; Tremont, Rolando; Cabrera, Carlos, Prof., UPR-RÍO PIEDRAS, Natural Sciences, Department of Chemistry
Characterization of the surface derivatization of Pt with mercapto and amine compounds using XPS and FT-IR

The self-assembled monolayers (SAMs) of organics over surfaces of solids has attracted attention in recent years due to its applications.1 Alkanethiols over precious metal surfaces are well known to form fine ordered monolayers. Some of the most used substrates are Ag, Pt, Cu and Au one of the most studied due to its high stability1. Fourier transform infrared (FT-IR) and X-ray phothoelectron spectroscopy techniques are important tools in the characterization of modified electrodes (2-4). In this study, surfaces of platinum electrodes were derivatized with mercapto and amine compounds, and acids as 3-mercaptopropionic acid (3-MPA), 16-mercaptohezadecanoic acid (16-MHDA), and 3-aminopropiltrimetoxysilane (3-APS). The derivatization was initiated by modifying the platinum surfaces with solutions of 1mM of 3-MPA or 16-MHDA in ethanol by SAM. The process was followed with the reaction of this resulting SAMs with 2mM solutions of 3-APS in dimethylformamide (DMF). The surface reaction process was followed with a spectrometer NEXUS 870 FT-IR equipped with SAGA accessory and an XPS spectrometer PHI 5600ci. The step of energy used in the XPS analysis was of 93eV for the survey analysis and 30eV for the studies of high resolution. The spectrum obtained by FT-IR at ~17000cm-1 corresponding the vC=0 in -COOH groups disappeared after the surface reaction was completed. The appearance of the band of adsorption at ~1565cm-1, corresponding to the band of amide II, in the SAMs, was observed. Bands of adsorption of other bonds in the compounds were also observed. The synthesis was also followed by XPS. These results show that the expected derivatization of the platinum surfaces was obtained.

References
1- Ulman, A., Chem Rev., 1996, 96, 15633.
2- Tao, Y.-T.,Pandiaraju,S,Lin,W.-L., and Chen, L.-J., Langmiur, 1998, 14,145.
3- Chapman, R.G., Ostuni,E., Yan, L., y Whitesides, M., Langmiur, 2000, 16,6927.
4- Persson, H.H.J., Caseri, W.R., y Sutter U.W., Langmiur, 2001, 17,3643.

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GARCÍA, KEVIN, UPR- MAYAGÜEZ, Industrial Biotechnology, UPR-MAYAGÜEZ; Rivera, Luis A. Prof., UPR-MAYAGÜEZ, Department of Chemistry
Systematic Spectroscopic Studies of the Family Members of
1’- substituted - 9 - (2’-Benzimidazolylmethylidene) Fluorenes

Some of the 2-substituted benzimidazoles have shown antiviral and other kind of diverse biological activities. Biological studies have been carried out on the modulation of the alveolar macrophage function by 9-fluorene derivatives, some of which have been used as membrane probes. The objective of this project is to prepare policyclic aromatic flourene derivatives, containing a benzimidazole nucleus that will carry out a photochemical electrocyclic rearrangement into the corresponding iminium ion. The characteristics of this system will then be evaluated electrochemically to elucidate their anticancer potential. In order to synthesize these compounds, we began the reaction sequence with the methylation of 2-methylbenzimidazole into the 1,2-dimethyl derivative, which was then oxidized into the 1-methyl-2-benzimidazole carboxaldehyde. Finally, the Wittig olefination of the aldehyde under phase-transfer conditions afforded the desired flourene derivative, which was purified and characterized by IR and NMR spectroscopies. The spectroscopic data obtained was consistent with the structure proposed. Future work will be concentrated on the preparation of other 1-substituted derivatives, such as ethyl, isopropyl and cyclopentyl groups.

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GONZÁLEZ RIVERA, RAQUEL; González, Yadira; Ramos, M., Prof., UPR-ARECIBO, Department of Physics and Chemistry
Use of a Simple Reflux System as a Digestion Method of Biological Samples

The use of a reflux system was evaluated as a digestion technique of biological matrices for the analysis of metals in environmental/inorganic samples. Although reflux methods have been widely used for mixing the reagents to carry out organic reactions, nothing has been published on the use of this system to prepare environmental/inorganic samples for trace metal analysis in analytical and instrumental analysis laboratory courses or as part of undergraduate research. We have established our sample preparation technique by using a simple reflux condensor system with highly pure reagents to break down tissues and quality controls to verify accuracy of measurements. Each sample was placed in a round bottom flask connected to a condensor and acid digested by refluxing the mixture. Quality controls consisted of standard reference materials (SRM’s) for plant and animal tissues, blank reagent samples and controls of digested plant root tissue which were spiked with a predetermined concentration (1.0 ppm) of copper and lead atomic absorption standard solutions, respectively. The quality controls were subjected to the same digestion process as the specimens. Samples were then analyzed by means of an Inductively Coupled Plasma-Optical Emission (ICP-OES) spectrometer. The apple leaves reference material was analyzed for barium, cadmium and copper. Recovery percentages of 90% Ba, 92% Cd and 97% Cu were obtained. Spiked root samples were analyzed for Cu and Pb, and the results obtained were 116% and 93%, respectively. The hepatopancreas reference material was analyzed for arsenic, cadmium, copper, manganese and zinc. Recovery percentages of 90% As, 106% Cd, 98% Cu, 97% Mn and 111% Zn. A spiked sample with Cu showed a recovery of 109%. The present work shows that the reflux system as a sample preparation technique is a simple device that reduces acid digestion contamination, results in minimal material loss, and it is a time-saving system.

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GONZÁLEZ, KARILYS; Montano, Nashbly; Pérez, Caroline; Griebenow, Kai, Prof., UPR-RÍO PIEDRAS, Natural Sciences Faculty, Department of Chemistry
Stabilization of a-chymotrypsin at methylene chloride/water interface: enzyme aggregation and its prevention by additives

The first emulsification step in the process of the encapsulation of proteins into bioerodible polymers by the water-in-oil-in-water (w/o/w) method is a principal cause for protein inactivation and aggregation. Herein, the serine protease a-chymotrypsin was employed as a model protein. Fourier-transform infrared (FT-IR) spectroscopy was used to study interface-induced perturbations in the secondary structure of a-chymotrypsin. When an aqueous solution of the enzyme was homogenized with methylene chloride, a procedure emulating the first step in the w/o/w encapsulation technique, aggregation and inactivation occurred. The FT-IR spectra demonstrated severe perturbations of the secondary structure. To overcome this, various additives were tested for their ability to prevent the detrimental events. Different polyols and polyethylene glycol (PEG, Mw 5000) were employed in the aqueous phase prior to emulsification and related to the magnitude of interface-induced protein aggregation and inactivation caused by emulsification. Some excipients, (e.g., maltose and lactose) were efficient in preventing protein aggregation, whereas others (e.g., lactulose and trehalose) were not. The efficient excipients identified will be tested for the capability to overcome instability problems during encapsulation of pharmaceutical proteins in polymer microspheres by the w/o/w technique.

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GONZÁLEZ, GLADYS D.; Ríos, Roberto, Prof., UPR-MAYAGÜEZ, Arts and Sciences Faculty, Department of Biology
Synthetic Studies of the Peripheral Benzodiazepine Receptor

Peripheral Benzodiazepine Receptors (PBR) are known to be concentrated in solid malignant tumor tissue. The physiological role of these sites is still not very clear, but is thought that they are related to cell growth and proliferation. We wanted to examine the effect of varying the oxidation states of the diazepine ring, including the three possible methylated derivatives to better understand the structural requirements of these ligands to their receptor. The synthesis and characterization of 7-Chloro-5-phenyl-1,4-benzodiazepine-2-one methylated derivatives will be presented. The affinities of these derivatives to the PBR will also be reported.

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GONZALEZ, ILEANA; Alvarez Avilés, O. and Rosario, O., Prof., UPR-RÍO PIEDRAS, Department of Chemistry
Development of Analytical Method for the Identification of Toxic Organic Compounds in Particulate Matter

Airborne particulate matter has been reported in several epidemiological studies as one of the principal causes of respiratory illnesses and other health conditions. Recently EPA has reported how fine particles in air affect the health of populations in USA attributing levels of mortality to contaminated air. Dr. Darwin Reyes (Ph.D. on August 1999) performed the first toxicological screening and chemical characterization of the organic compounds in particulate matter samples from Puerto Rico. The purpose of this work is to expand this study by developing an analytical method that will increase the percent of organic compounds that can be identified in particulate matter. Derivatization of the sample, combined with non-traditional ways of extraction and injection have increased the number of compounds that can be seen by GC/MS. Especially powerful has been direct thermal desorption of strips of filter sample. The use of HPLC with spectroscopic and mass spectrometry detectors have improved the identification of compounds that could be analyzed by GC/MS.

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GONZÁLEZ, MARYLIZ, PUCPR, Chemistry Department; Griebenow, Kai, Prof., UPR-RÍO PIEDRAS, Chemistry Department
Examination of Substrate Diffusional Limitations in Cyclodextrin and Crown Ether-Activated Biocatalysts

Enzymes in organic solvents have been recognized as useful catalysts in the synthesis of chiral compounds due to their high selectivity and specificity. Even though, there are still major drawbacks preventing synthetic chemists from employing them in their daily work. One such problem is the low enzyme activity in organic solvents when compared to that in aqueous media due to the increase in enzyme rigidity. We have found that the simple co-lyophilization of subtilisin Carlsberg, employed as model enzyme, with crown ethers (e.g. 18-crown-6, 15-crown-5, and 12-crown-4) and methyl-b-cyclodextrin (MbCD) suspended in organic solvents (e.g. THF) resulted in highly active and selective enzyme formulations. The acceleration of the initial rate (V0) ranged from less than 10-fold to more than 100-fold. To gain an insight of the factors causing the subtilisin activation, we investigated the effect of such additives on the substrate diffusion. First, we examined the enzyme formulations by imaging them by Scanning Electron Microscopy. We observed that all crown ethers create macroscopic pores in the co-lyophilizate powders. Meanwhile, MbCD did not. The pores in the crown ether-based formulation still remained after the removal of the additives. We propose that the formation of the pores is related to the absence of diffusional limitations. For diffusional limitations studies, the enzyme was inactivated by preincubating the enzyme with phenylmethanesulfonyl fluoride (PMSF) for 4 h. V0 at different fractions of active/inactive subtilisin co-lyophilized with and without MbCD and 12-crown-4 were determine for the transesterification of n-acetyl-L-phenylalanine ethyl ester with 1-propanol in anhydrous THF. A linear trend in the plot of V0 versus the percentage of the active subtilisin fraction will exclude diffusional limitations for that protein formulation. Analysis of 12-crown-4, MbCD- based formulations, and subtilisin lyophilized powder without additives are underway.

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GRACIA LUGO, ALEXIS J., UPR-MAYAGÜEZ, Arts & Science, Chemical Engineering; Souto Melgar, Antonio A.; Rodríguez Rodríguez, Lolita de los A.; De Jesús Echevarría, Maritza; Rodríguez Flores, Manuel; Souto Bachiller, Fernando, Prof., UPR-MAYAGÜEZ, Arts & Science, Department of Chemistry
Perfil Químico de Yerba Dulce (Lippia dulcis) In-vitro Aclimatada a Tierra

Lippia dulcis Trev. (Verbenaceae) es una hierba intensamente dulce usada desde tiempos remotos como una planta medicinal. En Puerto Rico L. dulcis se utiliza para tratamientos de la bronquitis, como sedante para la tos y para aliviar el cólico gastrointestinal. Esta hierba es la fuente de hernandulcina, un sesquiterpenoide que ha sido identificado como el principio dulce de la planta. Este compuesto químico se cató como 1500 veces más dulce que la sacarosa. En vista no sólo de la importancia farmacológica de esta planta, sino también por su interés industrial como fuente de edulcorantes naturales bajos en calorías, diversos grupos han estudiado y analizado extractos de L. dulcis por su contenido de hernandulcina. La planta existe como dos variaciones: una dulce, con hernandulcina como componente mayoritario y otra amarga, con alcanfor y hernandulcina como componentes mayoritarios. La presencia de alcanfor en la variedad amarga no favorece su posible uso en la industria como alimento o antiséptico. Las dos variedades no presentan diferencias morfológicas, por lo que el perfil químico se vuelve necesario para la identificación de las mismas.
En un estudio preliminar con L.dulcis in-vitro, se encontró que el cultivo de los vástagos por 6-8 semanas en agar condujo a una cantidad mayor de aceite esencial (60-80 mg/g), a unos niveles superiores de hernandulcina (18-26 mg/g peso seco) y la acumulación notable de otros sesquiterpenoides típicos de la planta silvestre adulta. Se observó también un aumento notable en la acumulación de escualeno (15% TIC)
junto a la ausencia del monoterpenoide tóxico alcanfor. Otro estudio preliminar, pero con la variación amarga de L.dulcis in-vitro, demostró que el aceite esencial (60 mg/g) se componía de 24% de alcanfor y 17% de hernandulcina. En estudios posteriores utilizando plantas in-vitro aclimatadas a tierra, se encontró que la variedad dulce de la planta proporciona hasta 32 mg/g de aceite esencial con una composición de 12% de hernandulcina y 0.0% de alcanfor. La variedad amarga proporciona la misma cantidad de aceite esencial, pero con una composición de 21% hernandulcina y 20% alcanfor. La determinación de estos y otros compuestos químicos característicos para L. dulcis servirán de base para otros estudios relacionados con las aplicaciones biotecnológicas de esta planta. El objetivo primordial de nuestra investigación es corroborar todos estos resultados previo a su publicación.

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HERNÁNDEZ, BRUNILDA; Ramírez, Doris, Prof., UPR-MAYAGÜEZ, Artes y Ciencias, Departamento de Química; Salas, Salvador, Prof., UPR-MAYAGÜEZ, Departamento de Horticultura
Extracción y Identificación de Giberelinas Endógenas en Coffea canephora (café robusta) y Coffea liberica (café excelsa)

Las giberelinas (GAs) son biorreguladores producidos en las plantas, que controlan procesos fisiológicos como el alargamiento del tallo, florecida, germinación y desarrollo tanto del fruto como de la semilla. Se han identificado 125 giberelinas conocidas comúnmente como GAs1-GAs125. Estudios previos en nuestro laboratorio han demostrado la presencia de la 2a-OH GA24, GA4, GA13 y GA34 catabolito en el café arábica. El propósito de esta investigación es extraer e identificar las giberelinas endógenas en el endospermo inmaduro de las semillas de otros dos cultivos de café: café robusta y café excelsa. Para esto, se homogenizaron las semillas inmaduras del café, se separaron los compuestos con actividad biológica utilizando extracciones orgánicas, cromatografías de absorción y cromatografía liquida de alta presión (HPLC). Se detectó la actividad biológica mediante la técnica de bioensayo de hipocotilo de lechuga (Lactuca sativa L.) en las fracciones eluidas por el HPLC. Se prepararon derivados sililados de las giberelinas y se identificaron por medio de su espectro de masa utilizando un cromatógrafo de gas acoplado con un detector de masa (GC-MS). Se encontraron las giberelinas 2a-OH GA24 y GA393-isovalerate en ambos tipos de café; excelsa y robusta. Estos resultados se compararon con los resultados obtenidos del café arábica y se halló que la presencia de la giberelina 2a-OH GA24 es común en los 3 tipos de café, a pesar de que los tres cultivos de café demuestran patrones de crecimiento diferentes.

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LÓPEZ RAMOS, VILMARÍ; Meléndez, Enrique; Cádiz, Mayra; Chaves, Tulio; Vega, Carmen A., Prof., UPR-MAYAGÜEZ, Arts & Science, Department of Chemistry
Electochemical Characterization and Analysis of Cp2MoCl2 with Nitrogenous Bases

The metallocen Bis(cyclopentadienyl)molybdenum dichloride, Cp2MoCl2, has been reported to exhibit impressive in vivo or in vitro antitumor activity against a range of tumor cell lines. Thus, the Cp2MoCl2 complex constitute a potent new class of organometallic antitumor agents. Like Cisplatin, the metallocene dichloride has also shown activity to inhibit DNA biosynthesis in cancer cells, but with less toxic side effects. At the present moment, its mechanism of action is poorly understood. The objective of this work is to analyze the electrochemical behavior of Cp2MoCl2 at physiological pH (7.0-7.4) and at acidic medium simulating the conditions of the cytosol. The electrochemical study of the interaction of Cp2MoCl2 with the nitrogenous bases that compose the DNA (Adenine, Cytosine, Guanine, and Thymine) help to identify with which nitrogenous bases it is more reactive. Solutions of Cp2MoCl2 in a buffer of NaCl/Trish × HCl are prepared. The solutions are analyzed by cyclic voltammetry using a Ag/AgCl reference electrode, a Pt wire as an auxiliary electrode and glassy carbon as the working electrode. The degree of interaction for a particular combination of Cp2MoCl2 with the nitrogenous bases under study is determined from the shape of the corresponding cyclic voltammogram.

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LUGO, YARELY; Santos, María A.; Romañach, Rodolfo, Prof., UPR-MAYAGÜEZ, Arts and Sciences, Department of Chemistry
Development of Near Infrared Spectroscopy for Content Uniformity: Analysis of Tablets with Low Drug Content

Interest in Near Infrared Spectroscopy (NIRS) is growing in the pharmaceutical industry. This analytical technique offers several advantages in the development of analytical methods. Some of those advantages are: reduction in analysis time, possible remote sampling, the spectra may be recorded in a non-invasive manner, possible use in a wide range of chemical and physical applications and analysis without sample preparation in most of the cases. In this study NIRS was used to analyze tablets with low drug content. The analyses with the NIRS need a reference method. The reference method used was the Ultraviolet Visible Spectrometry. The mixture of the active ingredient and the other excipients was prepared in the laboratory and the tablets were prepared in a 16 punch-compressing machine. Spectra were obtained by Diffuse Reflectance, where the incident infrared beam scatters from the tablet, and by transmittance measurements. The main goal was to compare the diffuse reflectance and transmittance methods in determining the drug content in tablets. The objective was also to obtain a calibration model. The calibration model was used to relate the output of the Near Infrared Spectrometer to the properties of the samples. The prediction was used to callenge the calibration model in predicting the drug content of the tablets.

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MANGUAL MELISSA; Olmo, John A.; Maldonado, Omar; Morel María; Avilés, Olga; Vázquez, Karellie; Rosario, Osvaldo, Prof., UPR-RÍO PIEDRAS, Department of Chemistry
Capillary Electrophoresis Studies of Chlorinated Humic Acids in Water

For years there have been questions regarding the chemical nature of the complex mixtures that are produced from the chlorination of humic substances in water as a result of the disinfection’s process carried out in water treatment plants. Several attempts have been made to develop a reliable analytical method for the analysis of these compounds. This is important to incorporate those compounds, which are responsible of the mutagenic activity into the list of regulated substances by the EPA. Previous studies do show that mutagenic or biological activity is present in fractions obtained from these complex mixtures known to have nonvolatile compounds. Using a model mixture of 5 compounds with several chlorine atoms, CE-UV and CE-MS was shown to be useful for the separation of these compounds. The separation media used was 25 mM ammonium carbonate using sample stacking with combined low pressure hydrodynamic and electrokinetic’s injection. Using 0.625 mM ammonium carbonate as the sample solution it was demonstrated that a monitoring method based on CE-MS without prior sample pretreatment is possible

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MEDINA, DANIA; Eric, M.; Taub, Dennis D., Prof., PUCPR, Department of Chemistry
G protein-coupled Receptor Desensitization and Cross-regulation Studies

G protein coupled receptors ( GPCR) are essential cell surface signaling molecules that play important roles in the genesis of immune responses to pathogen challenges or tissue trauma. A process called desensitization, wich occurs once a receptor has been exposed to either specific or shared ligands, or through shared signaling pathways, tightly controls the signal transduction pathways activated by these receptors. We sought to determine the existence of cross-regulation and desensitization processes between different families and subtypes of GPCR, focusing specifically on the chemokine and endothelial differentiation gene (EDG) receptors using the human leukemia HL-60 cell line as a model. Cells were cultured with a variety of differentiation agents before assessing the GPCR cross-regulation by monitoring changes in intracellular calcium mobilization after stimulation with specific and selective receptor agonists. Furthermore, receptor expression was verified by RT-PCR using the specific primers for various chemokine and EDG receptors. Among the many cross-regulations we observed, ligation of the CXCR-4 chemokine receptor by its specific ligand,SDF-1, inhibited the expected calcium response of HL60 cells to
the EDG receptor ligands LPA and S1P. Likewise, initial treatment of cells with LPA, or S1P influenced the calcium mobilization responses to SDF-1.Treatment with formyl peptide caused partial cross-desensitization of cellular responses to LPA, SDF-1, IL-8, and RANTES. The responsiveness to GPCR stimuli did not necessarily correlate with relative receptor expression by PCR. While the specific machanism(s) of this receptor signaling crosstalk is currently unknown, we believe that there are numerous unique and shared signaling pathways between various GPCR families that may cross-regulate their activities during an inflammatory-immune response and during normal homeostatic cell-cell interactions.

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MERCADO, EUNICE; Rodríguez, Glenda Lee, UPR-MAYAGÜEZ, Department of Chemistry; López Santiago, Omar, UPR-MAYAGÜEZ, Department of Chemical Engineering; Rodríguez López, Margarita, PUCPR, Deparment of Chemistry; Carrasquillo, Arnaldo, Prof., UPR-MAYAGÜEZ; Department of Chemistry
Bismuth-Induced Enhancement of Quinone/Hydroquinone (Q/HQ) Electron Transfer Kinetics at Polycrystalline Platinum Electrodes: Description of the Role of Bi3+(Aq) and Bi0(Ads)

The need for an atomic-level description of electrochemical (EC) reactions is now well established. Such a microscopic picture of (EC) processes is needed if current technological limitations in fuel cells, batteries, electrocatalysis and corrosion prevention are to be overcomed. For example, controlling the structure and composition of electrode/electrolyte interfaces can alter the electron-transfer kinetics of solution redox species. In this talk, (i) modern Surface Analysis techniques, (ii) Surface Science concepts, (iii) traditional EC methods, and (iv) the Electrode Surface Coordination Model are applied to the study of a selected EC system. Our research has surveyed the effect of both, aqueous bismuth ions (Bi3+(Aq)) in solution and surface-bound under potentially deposited (UPD) bismuth adatoms over the electron-transfer kinetics of a prototypical solution redox couple (Q/HQ) at polycrystalline platinum electrodes. Our data suggests that: (i) the presence of chemisorbed Bi0(Ads) prevents chemisorption of Quinone-derived species at the electrode solution interface, (ii) the presence of chemisorbed Bi0(Ads) exerts a dramatic enhancement in the electron-transfer kinetics of the Q/HQ redox couple, and (iii) the electron transfer kinetics of the Q/HQ couple decrease monotonically with decreasing Bi(Ads) surface coverage.

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MORALES, VERÓNICA; Pagán, Luis D.; Estévez, Juan G., Prof., UPR-CAYEY, Department of Chemistry
Effects of the Substituents: C6H5-, CH3-, NO2- in the Geometry and Association Energies in Quadruple Compounds of Hydrogen Bonded to the Dimers 2-Ureido-4 [1H]-pyrimidinone, Using the Semi Empirical AM1 Method

The last decades have demonstrated a growing interest in the development of chemical species that serve as building blocks in the development of supra-molecular structures. Among the interactions that can be present in these blocks is the formation of Hydrogen bonds. With the purpose of trying to understand and predict the species of maximum association energy, we have studied the effect of the substituents C6H5-, CH3-, NO2- in the R2 position. The study has been undertaken using the semi-empirical AM1 method. In all the cases studied, both the monomer and the dimer were assumed to initially have a planar geometry and their geometries have been calculated and optimized. The association energy was calculated as:

Association energy = Dimer energy – 2(monomer energy)

These results show that neither the monomers nor the dimers are planar. The association energies calculated show an increase with the donor power of groups in the following order -C6H5 > -CH3 > -H. However, the –NO2 attractor increases the interaction. The values determined for these energies are –21.514, -21.178, -20.756 and –23.584 kcal/mol, respectively.
None of the Hydrogen bonds are linear, owing to the fact that there is a complex interaction between donors and acceptors, due to a lateral displacement of the monomer in the dimer AADD/DDAA.

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NARVÁEZ ROSARIO, CARLA, UPR-MAYAGÜEZ, Arts & Sciences, Department of Biology; De Jesús Echevarría, Maritza; Rodríguez Rodríguez, Lolita; Souto Bachiller, Fernando, Prof., UPR-MAYAGÜEZ, Department of Chemistry
Estudio de la Diurésis y Acción Antilítica de la Planta Rubia tinctorum

Esta investigación está basada en el estudio de plantas medicinales utilizadas popularmente para tratar la piedra del riñón. Para este estudio se escogió la planta Rubia tinctorum conocida comúnmente como Rubia de tintoreros. La raíz de la Rubia tictorum ha sido utilizada desde tiempos remotos para combatir enfermedades del aparato urinario, pero la presencia de componentes tóxicos ha hecho que caiga en desuso. Nuestra hipótesis es que los compuestos antraquinónicos, alizarina y sus congéneres, presentes en la raiz, producen un efecto disolvente sobre los cálculos urinarios.
Primeramente buscamos germinar la planta in vitro a partir de semilla comercial ya que esta planta no es autóctona de Puerto Rico. Luego se realizaron experimentos de cultivo in vitro con hormonas (reguladores de crecimiento) para optimizar su cultivo (auxina IAA 0.0-1.0 ppm, citoquinina KIN 0.0-0.1 ppm) en medios líquido y semisólidos. Finalmente se preparó un macro abasto de la planta bajo condiciones óptimas (medio líquido de Murashige and Skoog con 0.9 ppm IAA y ausencia de kinetina). Esto fomenta el crecimiento de raíces y tallos y permite estudiar la composición química de la raíz. Las raíces fueron recolectadas para su análisis químico por cromatografía de gas acoplada a espectrometría de masas (GC/MS).
Finalmente preparamos decocciones de la raíz de planta madura del campo obtenida comercialmente y de la planta in vitro. Las decocciones se titularon con Ca+2 usando un electrodo selectivo de Ca que responde al calcio libre. Se observó una gran capacidad para atrapar iones de calcio en las decocciones de la planta madura, lo que es muy positivo para el tratamiento de la litiasis urinaria con esta planta, mientras que la planta cultivada in vitro mostró una menor capacidad. La decocción de la planta madura por su color rojizo muestra tener el glicósido de alizarina, que atrapa el Ca+2, mientras que la de la planta in vitro, por su color amarillento, muestra tener purpurina y ausencia de alizarina.

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OCASIO, YESSENIA; Cortés Figueroa, José, E., Prof., UPR-MAYAGÜEZ, Arts & Sciences, Chemical Engineering
A Chemical Kinetic Study of Fullerene-W(CO)5

The ligand exchange reactions of Fullerene-W(CO)5 with phosphines were study under flooding conditions in various solvents. The reaction mechanism seems to depends on the solvent. A mechanism change over from dissociative displacement to associative displacement is being proposed. The basis for the mechanistic interpretation will be presented and discussed in detail.
Acknowledgment: This work was supported by the donors of The petroleum research fund, administered by the American Chemical Society, NSF, and PRLS-AMP.

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O'NEILL, ROSANN; Cruz, Heidyleen; Carballeira, Néstor, Prof., UPR-RÍO PIEDRAS, Natural Sciences, Department of Chemistry
Towards the Total Synthesis of the Novel 13-Methyl-14-eicosenoic Acid from the Caribbean Sponge Spheciospongia cuspidifera

The fatty acids (E)-9-methyl-10-hexadecenoic acid (1), and (E)- 11-methyl-12-octadecenoic acid (2) belong to an uncommon series of bacterial fatty acids. These novel fatty acids were identified in the marine bacterium Vibrio alginolyticus and in the dinoflagellate Ostreopsis lenticularis, respectively. Just recently, we identified two additional fatty acids from this series in the sponge Spheciospongia cuspidifera. The structures of these fatty acids were tentatively assigned as 13-methyl-14-eicosenoic acid (3) and 17- methyl-18- tetracosenoic acid, on the basis of their mass spectra and gas chromatographic retention times of their corresponding methyl esters. In order to fully corroborate the structures of these fatty acids we developed a synthetic route for the 13-methyl-14-eicosenoic acid (3). One of the important intermediates in the proposed synthetic pathway is a macrocyclic lactone. Our initial efforts towards the synthesis of fatty acid 3 will be presented. (Rosann O’Neill thanks the UPR Río Piedras NIH- Marc program)

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ORTIZ SAIDA, UPR-HUMACAO, Química Industrial; MacDiarmid, Alan G., University of Pennsylvania, Department of Chemistry; Ortiz-Marciales, Margarita, Prof., UPR-HUMACAO, Química Industrial
Proceso Novel para Protonar Polianilina

Polianilina pertenece a un importante grupo de polímeros orgánicos conductores de electricidad redescubiertos por el Dr. Alan MacDiarmid. Polianilina existe en diferentes estados de oxidación, pero el único que tiene la propiedad de conducir es la sal de emeraldina. Se ha demostrado que cuando 2-nitrobenzaldehido (NBA) es expuesto a la luz ultra violeta (UV), la base emeraldina (EB) puede ser protonada por el ácido 2-nitrosobenzoico, el cual es producto de una reacción fotoquímica. Cuando una solución de EB y NBA en 1-metil-2-pyrrolidinona (NMP) fue expuesta a la luz UV por 30 minutos, ésta cambió de su color azul a verde y mostró la banda de absorción característica de la base emeraldina protonada. Para diseñar un producto que pueda ser usado como sensor de radiación, se utilizó poli(metil metacrilato) (PMMA) como material de soporte para fabricar películas de color azul-transparente uniformes y flexibles. Las películas se obtuvieron de una solución de EB, NBA y PMMA en NMP. Cambios en color se observaron luego de cinco horas de exponer las películas a la luz UV de una lámpara fluorescente, mientras que una película de igual composición cambió de color en dos horas cuando se expuso a la luz solar.

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ORTIZ FLORES, YEMILYN, UPR-CAYEY, Department of Chemistry; Cintrón, José M.; Colón, Luis A., Prof., University at Buffalo, The State University of New York, Department of Chemistry
Synthesis of a Cyclodextrin-Silane Derivative as a Precursor for a Sol-Gel-Derived Chiral Stationary Phase for HPLC and CEC

Chiral separations are very important in synthetic and medicinal chemistry as well as in pharmaceutical applications. There are several chiral selectors that can be used in separation methods such as capillary
electrophoresis (CE), capillary electrochromatography (CEC) and liquid chromatography (LC). Chiral selectors in CE are used as additives to the run buffer, being cyclodextrins the most widely used. However, in CEC and LC they are immobilized on support materials, acting as stationary phases. We are interested in the design of a pH stable chiral stationary phase containing cyclodextrin that can be used at high and low pH. Sol-gel derived stationary phases have been shown to be very stable in a wide pH range. In addition, sol-gel processing offers a one-step reaction for the synthesis of bonded phases for CEC and LC, avoiding multiple step reactions. In order to fabricate a silica-based sol-gel derived phase containing a cyclodextrin, a precursor that can be incorporated in the sol-gel process must be synthesized. This can be achieved by the derivatization of β-cyclodextrin with a vinyl monomer to subsequently use it in the hydrosilation process to form an alkoxysilane that can be used in the sol-gel process. To this end, b-cyclodextrin was derivatized with the N-methylolacrylamide (NMA) with a 97% yield. The double bond content was of 0.409 mmol/g β-CD-NMA, which corresponds approximately to 1 molecule of NMA per β-CD molecule. The derivatized CD was submitted to a hydrosilation reaction using a Pto metal complex (Karsdet’s catalyst) or AIBN as a free radical initiator. The IR spectraum shows a reduction of the band corresponding to the vinyl group, which suggests that the β-CD alkoxysilane was synthesized. The hydrosilation reaction seems to be more effective using AIBN than the Karsdet’s catalyst, based on the reduction of the band corresponding to the vinyl group in the IR spectrum. As part of the future work the hydrosilation reaction must be optimized to completely react the β-CD-NMA, since a small band for the vinyl group was present in the IR spectrum, indicating unreacted β-CD-NMA. The next step in our approach will be to use the b-cyclodextrin-silane in the synthesis of silica-base particles by the sol-gel process.

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PAGÉS ELAINE; Díaz, Emilio, Prof., UPR-MAYAGÜEZ, Arts and Science, Department of Chemistry
Isolation and Characterization of Histidine Decarboxylase

Histidine decarboxylase catalyzes the formation of histamine from the amino acid histidine. Histamine causes poisoning in humans when present in food products that have been contaminated by bacteria that produce it, like fish and dairy products. My objective was to isolate and eventually characterize the enzyme from three bacteria: Enterobacter cloacae, Enterobacter aerogenes and Morganella morganii. My job consisted on the preparation of a series of growth cultures and the development of a radioactive assay for the detection of histidine decarboxylase using a commercial enzyme: L-histidine decarboxylase of Lactobacillus.
The bacteria had to go through a series of cultures in order to assure their viability and growth since they were at freezing temperature for a long period of time. Nutrient agar was used for the growth cultures. Then, a test to detect the presence of the enzyme in the three bacteria was done, using Niven culture medium. This medium contains 5.0 g of sodium chloride, 1.0 g calcium carbonate, 5.0 g of bacto triptone, 5.0 g of bacto yeast extra ct, 27g of histidine, 25g of agar and 0.06g of the purple indicator bromo cresol. The three bacteria grew in the growth cultures. The results for Niven's test were positive: the medium changes from a yellow-green color (pH 5.3) to a purple color (basic pH ). The color change is due to the histamine present in the three bacteria studied.
Finally, several assays whose purpose was to detect the activity of L-histidine decarboxylase from Lactobacillus were done. The first assay consisted of Niven medium modified as broth, without the agar, and an acetate, glycerol and EDTA buffer at a pH of 5.3. The second assay consisted of a solution with acetate buffer, the cofactor pyridoxal phosphate, histidine and the red indicator phenolphthalein at a pH of 6.5. The third assay consisted of the same solution used for the second assay but with the violet indicator bromo cresol at a pH of 6. The results obtained will be presented.

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PARALITICCI GIOVANNI; Martí, Angel A.; Colón, Jorge L., Prof., UPR-RÍO PIEDRAS, Natural Sciences, Department of Chemistry
Spectroscopic Characterization of Methyl Viologen Encapsulated into a-Zirconium Phosphate

The N, N’- dimethyl-4, 4’-bipyridinium, also known as methylviologen (MV2+) or paraquat is widely used as an electron-transfer indicator in studies of chemical, biological and photochemical redox reactions. In the past two decades, the potential applications of methylviologen in solar energy conversion and storage have captured great attention. In addition, among inorganic compounds, layered metal oxides and phosphates occupy a prominent position for exploring artificial photochemical and photophysical process in restricted media. The small size and its 2+ charge make this reagent suitable to be ion exchanged into the a-zirconium phosphate galleries. We have characterized MV2+-exchange at a-ZrP by: UV- visible spectrophotometry, Luminescent spectroscopy and X-ray Powder diffraction.

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PASTRANA EMIL, UPR-RÍO PIEDRAS, Natural Sciences, Department of Chemistry; Al-Azzam, Wasfi; Ferrer, Yancy, UPR-RÍO PIEDRAS, Department of Biology; Griebenow, Kai, Prof., UPR-RÍO PIEDRAS, Department of Chemistry
Non–Aqueous Encapsulation of Bovine Serum Albumin Co-lyophilized with Poly(ethylene glycol) in Poly(lactide-co-glycolide) Microspheres

Novel therapeutic techniques are being developed involving protein encapsulation into biodegradable polymers. One of the methods used to encapsulate pharmaceutical proteins is the solid-in-oil-in-oil (s/o/o) technique. However, this method has some draw-backs, for example, structural perturbations of encapsulated protein, low encapsulation efficiency, and formation of protein aggregates can occur. The effect of poly (ethylene glycol) (PEG, Mw of 5,000 and 8,000) co-lyophilized with the model protein bovine serum albumin (BSA) was studied on the protein’s stability. Upon suspension of BSA-PEG in methylene chloride, the diameter of the protein powder particles was reduced to less than 1 mm. The micronization of the protein powder in the s/o step facilitated the improvement of the encapsulation efficiency from ca. 30% to over 90%. The co-lyophilization of PEG with BSA also prevented formation of soluble aggregates upon in vitro release as monitored by size exclusion chromatography. The formation of insoluble aggregates was also completely prevented. Sustained release proceeded over a period of 2 months. In summary, the effect of PEG as an additive in the s/o/o technique is useful in minimizing the formation of protein aggregates and in achieving higher encapsulation efficiencies.

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PÉREZ, JOSÉ; Morales, Daisy, PUCPR, Department of Chemistry; Infante, Gabriel, Prof., UPR-CAYEY, Department of Chemistry
Determinación de Metales en las Aguas Circundantes a Vertederos del Area Sur de Puerto Rico

La contaminación del agua puede ser ocasionada por la disolución natural de materiales geológicos o por la actividad humana. La mayoría de las aguas subterráneas contiene una variedad de sustancias químicas disueltas. Los contaminantes que típicamente fluyen a las aguas subterráneas pueden estar en niveles elevados sobre los permitidos luego que se dispersan a través de los acuíferos. Los contaminantes más comunes en el agua subterránea son los metales, compuestos orgánicos volátiles, plaguicidas, sales y otros derivados del petróleo. La toxicidad de los metales a nivel de trazas depende principalmente de la especiación química y física. Los vertederos sanitarios son una fuente de contaminación de las aguas subterráneas. Esta investigación pretende determinar la presencia y concentración de algunos metales en aguas subterráneas cercanas a vertederos y cómo varía la concentración de los metales en la región montañosa (Jayuya) versus el llano (Lajas). El estudio puede determinar si hay alguna filtración en las capas del vertedero y así evitar que se contaminen las aguas subterráneas. Utilizando un espectrofotómetro Perkin Elmer de Plasma Acoplado Inducido (ICP) se determinaron las concentraciones de catorce (14) metales. Luego de concluído el estudio se encontró que los elementos con mayor concentración en aguas subterráneas adyacentes a ambos vertederos fueron el Al (69.88mg/L) en Jayuya y 24.37 mg/L en Lajas. La concentración de calcio fue mayor en Lajas (330.40mg/L) que en Jayuya (62.23mg/L). La concentración de Magnesio fue mayor en Lajas (170.46mg/L) que en Jayuya (80.15mg/L). El Hierro está bastante alto en ambos vertederos. Esperamos que estos estudios puedan servir para controlar la contaminación en las aguas subterráneas circundantes a vertederos de desperdicios sólidos.

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PRIETO FIGUEROA, JOSÉ A., UPR-MAYAGÜEZ, Ciencias Agrícolas; Rodríguez Rodríguez, Lolita; De Jesús Echevarría, Maritza; Souto Bachiller, Fernando, Prof., UPR-MAYAGÜEZ, Department of Chemistry
Capacidad de la Planta Tagetes patula para el Control Biológico de Nemátodos: Estudio de la Composición Química del Aceite Esencial de la Flor

Las plantas del género Tagetes spp., conocidas en inglés como “Marigolds,” son muy populares tanto por las hermosas flores que producen como por sus propiedades para repeler nemátodos fitoparasíticos. El uso intercalado de estas plantas como práctica de control de plagas en sistemas de producción agrícola orgánica ha sido exitoso para el control de nemátodos en cultivos susceptibles.
Esta investigación se dirige al estudio de la composición química de la planta buscando el constituyente con actividad nematicida. Para este propósito se realizó una búsqueda bibliográfica de la planta y se adquirió comercialmente el aceite esencial de la misma para comenzar a estudiar su composición química por cromatografía de gas acoplada a espectrometría de masas (GC/MS). Simultáneamente se inició el
cultivo de la planta en tierra a partir de semilla y su cultivo in vitro, buscando las condiciones óptimas para su germinación y propagación.
Del aceite esencial comercial de la flor de T. patula se ha logrado identificar tentativamente 8 compuestos volátiles que componen 52 % del aceite. Los componentes mayoritarios identificados fueron el cis-ocimeno ( 27.54 %), alocimeno (8.55%), 2,6-dimetil-5,7-octadieno-4-ona, fenol, 3-(1,1-dimetiletil (2.32%) E-ocimenona (2.26%) trans-cariofileno (2.12%) alfa-humeleno (1.06%) biciclogermacren0 (1.80%). Se ha logrado germinar de manera aséptica sus semillas lo que ha sido difícil pues presentaban dormancia. Las plantas cultivadas se utilizarán para el estudio de la composición química de las partes reproductivas y vegetativas. También se ha logrado aislar una cantidad sustancial de especímenes de nemátodos para estudiar el potencial nematicida de la planta comenzando el estudio con el aceite esencial.

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RÍOS MAYRA; Hernández, Samuel P.; Mina, Nairmen, Prof., UPR-MAYAGÜEZ, Department of Chemistry
Detection of Energetic Materials by GC with Chemiluminescent Detection

The detection of explosive devices and compounds potentially energetic or toxic to humans and animals is an area of interest for several Federal Agencies. Advanced equipment has been designed and used to achieve this goal. High-speed gas chromatography with chemiluminescent detection is a new technique in explosive detection. In order to develop an analytical methodology, diluted standard solutions acquired from Radiant International, Analytical Materials, Austin TX are being used this work to detect Ammonium Nitrate (AN), black powders, and smokeless powders, with the EGIS Thermedics 3000. In addition, high-speed gas chromatography with chemiluminescent detection was used to measure the limits of detection of these energetic substances.

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RIVERA MILLÁN, LIZMARIE; Cordonés Emelyn; Castro Verónica; Alegría Antonio, Prof., UPR-HUMACAO, Department of Chemistry
Effect of Lipid Membrane Charge on the Quinone-Catalyzed Oxidation of Ascorbate

The efficiency of the electron-transfer processes from the semiquinone to biologically relevant targets, specially electron transfer to oxygen, should depend on its thermodynamic stability, which is a function of the semiquinone structure and environmental characteristics. In this work we have determined the role of membrane presence and charge in the rate of oxygen consumption by hydrophylic and hydrophobic quinones in the presence of ascorbate. For a highly water-soluble quinone no changes in the initial rates of oxygen consumption was detected with neither neutral, positive or negative phospholipid large unilamellar vesicles. For more hydrophobic quinones, a large increase in oxygen consumption rate was detected in the presence of a positively-charged membrane, although a decrease or no change in this rate was observed in the presence of neutral or negatively charged membranes. These observations are explained in terms of quinone and ascorbate absorption to the membrane surface or semiquinone stabilization.

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RIVERA, LUIS; Cortés Figueroa, José E., Prof., UPR-MAYAGÜEZ, Department of Chemistry; Ocasio, Yessenia, UPR-MAYAGÜEZ, Department of Chemical Engineering
Determination of W-Fullerene Bond dissociation Energy

The ligand (L) exchange reactions of Fullerene-W(CO)5 complex produce the complexes (L)W(CO)5 (L = PPh3 and P(Et)3). The reactions are first order with respect to Fullerene-W(CO)5. The observed order with respect to L is complex depends on the experimental conditions. The fullerene-W bond dissociation energy was estimated from the enthalpy and energy of activation of the step where fullerene dissociates from the inorganic Moiety. The mechanism of the reactions will be presented and discussed in detail.
[Acknowledgments: This work was supported by the donors of The petroleum research fund, administered by the American Chemical Society, the National Science Foundation, and PRLS-AMP.]

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RIVERA NORIDZA; Martínez, Angel; Colón, Jorge, Prof., UPR-RÍO PIEDRAS, Natural Sciences, Department of Chemistry
Ion-exchange of Re(bpy)(CO)3Cl into alpha-Zirconium Phosphate

Multilayer films prepared from high density inorganic polyanions, such as zirconium phosphate, have been studied and characterized progressively in recent years because of their potential applications in a variety of surface dependant technologies. Because of their ion-exchange properties these layers can be used to immobilize different kinds of molecules. The metal-inorganic complex Re(bpy)(CO)3Cl, which exhibits a charge transfer absorption and luminescence was ion-exchanged into this zirconium phosphate material. We have characterized Re(bpy)(CO)3Cl-exchanged ZrP with different spectroscopic and diffraction techniques like UV-Visible Spectrophotometry, Luminescence Spectrometry and X-Ray Power Diffraction.

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RIVERA COLLAZO LUIS D., UPR-MAYAGÜEZ, Department of Chemistry; Martínez, Gustavo, Agricultural Experimental Station, RÍO PIEDRAS; Vera, Marisol, Prof., UPR-MAYAGÜEZ, Department of Chemistry
FT-IR Characterization of Humic Substances in Soils with Different Hydrophobicity

Humic substances are related to the hydrophobicity of soils. Our research efforts are aimed toward determining compositional differences in humic substances extracted from the same type of soil (Typic Haplohumults, Río Piedras Series) but with different Water Drop Penetration Test (WDPT) results. The techniques being used to characterize the soils are: Fourier Transform Infrared Spectroscopy (FT-IR), in the Diffuse Reflectance mode, and Fourier Transform Nuclear Magnetic Resonance Spectroscopy (FT-NMR). The humic substances were extracted from a Mahogany Plantation located at the Agricultural Experimental Station and the “Bosque Urbano” (urban forest), both in Río Piedras. Their WDPT results are: 4.4 seconds and 231 seconds, respectively. The humic and fulvic acids were separated and analyzed individually by FT-IR. The FTIR region around 3100 and 2700 cm-1 shows the most variation in intensity and shape. This region contains signals corresponding to vibrations of the vinyl CH (=C-H) (3040 cm-1) and the symmetric and asymmetric CH2. The GRAMS curve fitting routine was used to deconvolute the band and integrate the individual contributions. These results and their relationship to the hydrophobicity test will be discussed.

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RIVERA-MORALES RACHEL; Lebrón-Paler, Ariel, UPR-CAYEY, Department of Chemistry; De Jesús-Cardona, Héctor, UPR-Bayamón, Department of Chemistry; Castro-Santiago, Raúl J., Prof., UPR-CAYEY, Department of Chemistry
Voltammetric study of the adsorption of benzenethiol on Gold electrode

In the current investigation we are working with the alkanethiol known as benzenethiol. This organic compound is being tested as a possible protective agent against corrosion on the surface of gold. From recent studies made in this area, it is known that alkanethiols are adsorbed to metallic surfaces, although the mechanism of this process is not fully understood. To conduct our experiments we are using the technique known as Cyclic Voltammetry, where the working electrode is made of a metallic surface, in our case gold. Several experiments were made to characterize benzenethiol: effect of concentration, initial potential, and equilibrium time before starting the voltammetry. Our findings include the identification of significant adsorption on the surface of the Gold electrode. The studies of concentration have been successful in identifying an optimum concentration for the experiments. The preliminary results from the initial potential and equilibrium time experiments suggest that there is no relationship between these effects and the adsorption behavior of benzenethiol on the gold surface.

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ROBLES KARINA, PUCPR, Biology; Santos, Lizette, PUCPR, Department of Chemistry
Toxic consequence caused by Hibiscus rosa-sinensis in Artemia Salina

Many plants have demonstrated to be useful as healing remedies, although some might be considered as toxic or poisonous. In this research the Hibiscus rosa-sinensis is analyzed to study the elements (metals) present to view the consequence of its toxicity on Artemia Salina. As a result of this, can be inferred if the Hibiscus rosa-sinensis should or should not be catalogued as a healing plant. The final purpose of this research is to determine the toxicity of the Hibiscus rosa-sinensis in the Artemia Salina and from that to demonstrate if it is a toxic or healing plant.To accomplish this work the following procedures were completed. The General Method for Elements (metals) Determination was realized first and it consisted of dividing leaves and stems of Hibiscus rosa-sinensis. Mashed leaves and stems were mixed in HNO3 and HCl and then heated on a hot plate. Both samples were filtrated and mixed with deionized water for the analysis. Then the Toxicity Test: Artemia Salina Bioassay was realized. The Hibiscus leaves were divided in groups of aqueous extract (mixed in water) and organic extract (mixed in methanol). The samples were evaporated completely to add the appropriate solvent. With this, a stock solution was made from each extract to prepare three initial concentrations for analysis. The Artemia Salina were prepared in artificial seawater and added to the prepared solutions of aqueous and organic extracts to be analyzed. In spite of what the information explains about the Hibiscus rosa-sinensis, that it is considered as a non-toxic plant, this research showed that it is a toxic one because metals were found and due to that it had a negative consequence on the Artemia Salina. With other analysis this plant can specify for what medicine reasons might be helpful.

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RODRÍGUEZ, MILDRED, UPR-HUMACAO, Department of Chemistry; Rovira, Nahyr; Cadiz, Mayra; Hernández, Samuel, UPR- MAYAGÜEZ, Department of Chemistry
Espectroscopia Raman aumentada por superficie (SERS) de la interacción entre ADN y Complejos de Platino.

El complejo cis-[Pt(NH3)2(tiazol)Cl]+ muestra actividad biológica y forma enlaces covalentes con el ADN. En este trabajo se investigó la interacción de este complejo con ADN de timo de becerro mediante la técnica de Espectroscopia Raman Aumentada por Superficie (SERS). Se prepararon soluciones del ADN, cis-[Pt(NH3) 2 (tiazol)Cl]+ y una mezcla de ambos en una proporción [Pt]/[ADN] = 0.25. Las muestras se prepararon en un amortiguador de fosfato de potasio, pH=7.40, y se encubaron por 24 horas. Bajo condiciones similares, se estudió también la droga anticancerígena cisplatino {cis-[PtCl2(NH3) 2]}. Los espectros SERS se obtuvieron sobre coloides de plata. En los espectros de las mezclas ADN-complejo Pt predominaron las bandas vibracionales de los complejos metálicos por sobre las del ADN. La banda intensa de la vibración Pt-NH3 se observó en las mezclas alrededor de los 540cm-1, y su intensidad aumentó considerablemente en el espectro del ADN con cisplatino. Entre los cambios más significativos, estuvo la aparición de bandas en la región de 1500-1602cm-1, los que se asocian a modificaciones en las vibraciones de las bases del ADN causadas por la coordinación del Pt.

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RODRÍGUEZ, JAÍTZA; Torres-Silva, Ivelisse and Rosario, Osvaldo, Prof., UPR-RÍO PIEDRAS,Department of Chemistry
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 science. 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 environment in order to know the exposure to humans and wildlife. The purpose of this investigation is to develop and validate methodology to study EDCs in seawater. SPME is being used as the extraction technique and GC/MS for the chemical analysis. A model matrix for seawater was prepared using distilled water in which representative salt mixtures and microelements were added. Experiments were performed to adjust important parameters in the SPME extraction such as fiber type, co-solvent effect, stirring intensity and extraction time. Polydimethylsiloxane/ divinylbenzene 65µm fiber was better for the extraction of the phthalate esters studied from the model matrix in comparison with the Polyacrylate 85µm, PDMS 100µm and PDMS 7µm fibers. An extraction time of 45 minutes was determined from the extraction time profiles as well as practical limitations. A co-solvent was used to assure dissolution of the standards in water. A proportion of 200µL of acetone/ liter of water (0.02% v/v) gave in general better results. The effect of multiple samplings on the fiber was studied using SEM. Additional experiments will be performed to optimize and validate the methodology.

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SANTAMARINA RODRÍGUEZ LOURDES M., UPR-MAYAGÜEZ, Chemistry Department; Echegoyen, Luis, Clemson University, Department of Chemistry; Rivera, Luis A., Prof., UPR-MAYAGÜEZ
Design, Synthesis and Characterization of 5,5'-(7-Noenyl-1-ol)-2,2'-(oxybis(3-oxydimethyleneoxy) bis (N-(1-pyrenylmethyl) benzamide as a Potential Chemical Sensor Anchored on a Polymeric Support

The title compound was designed to have a chemical sensor based on fluorescence from the interaction between the two pyrene moieties as a result of the conformational changes upor coordination to cations, thereby eliciting the emission. The synthetic strategy involves the modification of the hydroxy, carboxylic and aldehydic groups in 5-formylsalicylic acid, while maintaining their position in the benzene ring. The Wittig olefination on the benzaldehydic group permitted the introduction of a 9-nonenyl side chains that will be used to anchor the sensor to a polymeric support. Analysis and characterization of the intermidiates and final product was performed by interpretation of the GC-MS (FAB) and IR, proton and carbon-13 NMR spectral data.

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SOLÁ, JESSICA; Rodriguez, Lolita; De Jesus, Maritza; Solá, Jessica, UPR-MAYAGÜEZ, Biotecnología Industrial; Souto, Fernando, Prof., UPR MAYAGÜEZ, Department of Chemistry
Determinacion de la Composicion Quimica de la Lepianthes peltatum "in vivo" e "in vitro"

La especie Lepianthes peltatum es una planta que pertenece a la Familia Piperaceae. Esta especie tiene aplicaciones como diurético y antilítico. A pesar del amplio uso medicinal que esta planta posee, pocos estudios fitoquímicos se han realizado. Esto motivó el presente estudio fitoquímico de la especie silvestre e "in vitro". Como parte del mismo, se mantuvo el abasto de dicha especie mediante el subcultivo de secciones internodulares en medio sólido con sales de Murashige and Skoog (M S). Se recolectó el material de mayor interés, las hojas (hoja + pecíolo) “in vitro” e “in vivo” y se determinó la biomasa. El presente estudio presenta el análisis de la composición química de la L.peltatum “in vivo” e “in vitro” a traves de los resultados obtenidos mediante la tecnica de cromatografia de gas acoplado a un detector selectivo de masa (GC-MS). Se compararon los componentes químicos mayoritarios en la L. peltatum “in vivo”e “in vitro”, con mayor énfasis al compuesto 4-nerolidilcatechol.

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SUÁREZ ALEXIS, UPR-CAYEY, Department of Chemistry; Lebrón-Paler, Ariel, UPR-CAYEY, Department of Chemistry; De Jesús-Cardona, Héctor, UPR-BAYAMÓN, Department of Chemistry; Castro-Santiago, Raúl J., UPR-CAYEY, Department of Chemistry
Quartz Crystal Microbalance and Voltammetric Studies for the Adsorption of Benzenethiol on Gold

The interaction between a metal and its surrounding atmospheric environment is of great importance in many processes such as corrosion. It is known that thiol (R-SH) molecules have a strong interaction with metal surfaces. Moreover, many alkyl mercaptan derivatives undergo self-assembly to form organized monolayers on metal surfaces. These mercaptan compounds have been studied as possible metal corrosion inhibitors. In order to understand the corrosion inhibition processes, there is a need to characterize the metal\thiol interface. We used the QCM (mass sensitive device) and voltammetric techniques (cyclic and linear voltammetry) to study the adsorption of benzenethiol on gold from an ethanolic solution. QCM results show a decreasing pattern in frequency during the adsorption of benzenethiol. The voltammetric results showed a reproducible behavior for the adsorption and desorption process. These results suggest the formation of a very stable thin film of benzenethiol on the gold surface.

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TORRES, MICHELLE; Santos, Lizette, Prof., PUCPR, Department of Chemistry
El efecto del Lycopersicon sculentum Mill en el tiempo de coagulación de la sangre

Se efectuó una investigación para establecer la efectividad del tomate como alternativa para los seres humanos con problemas relacionados con la coagulación de la sangre. Se determinó el tiempo de coagulación en muestras de sangre obtenidas de veinte voluntarios saludables escogidos aleatoriamente. Se le orientó sobre el propósito de la investigación y las pruebas que se le suministrarían a la sangre para detectar aquellos desórdenes que afectan la formación de un coágulo. Las pruebas fueron: APTT (Activate Partial Thromboplastin Time), PT (Prothrombin Time) y “Bleeding Time”.La investigación fue de tipo experimental y se compararon las muestras con los diferentes tratamientos: orgánico, acuoso, tomate fresco y heparina. Los resultados de la investigación muestran diferencias significativas en el tiempo de coagulación de la sangre. El valor p fue menor de 0.05 (p = 0.001). Los tratamientos administrados a la sangre con tomate fresco, ciclohexano y extracto acuoso tuvieron resultados positivos, inhibiendo la coagulación de la sangre. El tratamiento suministrado con diclorometano presentó una variación en los resultados obtenidos, dando un tiempo de coagulación promedio de 29.7 minutos. El tiempo límite establecido para una coagulación completa de la sangre fue de treinta minutos.

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VARGAS PINTO, SUSANA, UPR-MAYAGÜEZ, Dept. of Biology; Rivera Montalvo, Luis A., Prof., UPR-MAYAGÜEZ, Department of Chemistry
Synthesis, Characterization and Potential Biological Activity of 9-benzothiazolylmethylidenefluorene

Recently, benzofluorenone has been used for the preparation of diverse kinamycin antibiotic intermediates for biosynthetic studies. The kinamycin family of compounds have been determined to be derivatives of benzo[b]fluorene, which exhibits anti-infective and anticancer activities. Other fluorene derivatives, such as, 4-(7-benzothiazol-2-yl-9,9-didecylfluoren-2-yl)diphenylamine and derivatives thereof, are potentially useful fluorophores in two-photon fluorescence microscopy. The synthesis of the highly functionalized and conjugated title compound will be discussed. The synthetic scheme involves heterocyclic chemistry and the use of the Wittig heterocyclic olefination under phase transfer catalytic conditions for the critical regiospecific formation of the double bond.