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Natural Science |
Ayala-Burgos, Norma; Betancourt, José E.; Carballeira, Néstor M.* Natural Sciences, UPR-Río Piedras
Synthesis of
(5Z,9Z)-14-methyl-5,9-pentadecadienoic acid as apotential
topoisomerase I inhibitor
We have recently shown that the naturally occurring
(5Z,9Z)-5,9-hexadecadienoic acid inhibits human topoisomerase I at
a concentration of 800 micromolar, while the 5,9-hexadecadiynoic
acid and hexadecanoic acid do not inhibit topoisomerase I (>1000
micromolar). This comparison revealed that the cis double bond
geometry in the dienoic acid was required for topoisomerase I
inhibition. The (5Z,9Z)–5,9-hexadecadienoic acid was antimicrobial
against the Gram-positive bacteria Staphylococcus aureus (MIC 0.08
micromol/mL) and Streptococcus faecalis (MIC 0.20 micromol/mL),
but inactive against Gram-negative bacteria such as Pseudomonas
aeruginosa. These inhibitory activities have led us to conclude
that probably this antimicrobial activity of the
5,9-hexadecadienoic acid was probably due to topoisomerase I
inhibition. Methyl-branched iso fatty acids have recently been
shown to inhibit topoisomerase I. Therefore, we expected for the
naturally occurring (5Z,9Z)-14-methyl-5,9-pentadecadienoic acid,
which is also antimicrobial to the Gram-positive bacteria
Staphylococcus aureus (MIC 0.24 micromol/mL) and Streptococcus
faecalis (MIC 0.16 micromol/mL), to be an even better
topoisomerase I inhibitor than the normal-chain 5,9-hexadecadiene
acid. Therefore, we have synthesized the stereochemically pure iso
delta 5,9-16:2 acid in six steps starting with commercially
available 1,5-hexadiyne and determined its topoisomerase I
inhibitory activity. Our results will be presented herein.
Castillo Irizarry, Myritza; UPR-BAYAMON, Natural Sciences; Legault, Marc D.* Dept. of Physics, UPR-Bayamon; Barletta, Gabriel*, Dept. of Chemistry, UPR-Humacao
A theoretical approach to study the proton and electronic distribution in the catalytic triad of subtilisin carlsberg during catalysis
The objective of this research is to investigate the proton swapping between the catalytic-triad residues of a serine protease during catalysis. The movement of these protons can justify a charge transfer that occurs between the aspartic residue and the serine residue. Another alternative has been proposed for this charge transfer: the ring-flip mechanism. It was recently postulated that charge is transferred by rotation of the imidazole ring 180 degrees. This scenario will also be examined in this research. Accurate quantum mechanical calculations were performed on a very restricted part of the enzyme: the catalytic triad only. By performing partial geometrical optimizations on the catalytic triad one can determine the most energetically favorable position of these protons. By changing the total charge of the system one can also simulate the presence of a tetrahedral intermediate bound to the hydroxyl of the serine residue. The ring-flip mechanism was also studied by performing various partial geometrical optimizations function of the rotation of the imidazol ring.
Fuentes, Jennifer; Acevedo Rodríguez, Melissa; Molina, Erick F.*, Departamento de Ciencias Naturales, UPR-Aguadilla
Análisis de los compuestos volátiles responsables del aroma de una cerveza tipo ale mediante SPME-GC/MS
La cerveza es una bebida alcohólica hecha de granos de cereal (cebada, arroz, trigo, maíz). Los granos liberan enzimas y azúcares los cuales son utilizados por la levadura para producir alcohol y el sabor característico de la cerveza. Más de setenta estilos diferentes de cerveza están disponibles hoy en día para satisfacer el paladar de millones de personas alrededor del mundo. En los Estados Unidos, por ejemplo, 880 cervecerías produjeron más de 200 millones de barriles de cerveza, y, en promedio, cada adulto americano consumió casi 32 galones de cerveza en 1995. Cada estilo de cerveza deriva sus características únicas de sus ingredientes y diferencias sutiles en el proceso de elaboración. Hoy en día resulta esencial determinar la naturaleza de los ingredientes utilizados para elaborar la cerveza, específicamente los granos utilizados, pues la calidad del producto final depende de éstos. Determinar si en una cerveza han sido utilizados derivados de maíz para abaratar costos es muy importante para el consumidor, por lo que nos hemos dado a la tarea de establecer un método para analizar el aroma de la cerveza con el propósito de correlacionar los compuestos volátiles responsables del aroma de la misma con los tipos de grano utilizados en el proceso. El primer paso para alcanzar nuestros objetivos ha sido evaluar la técnica de microextracción en fase sólida (SPME por sus siglas en inglés) para obtener una muestra del aroma de una cerveza tipo ale elaborada en nuestro laboratorio de investigación. Posteriormente la muestra debe ser analizada mediante la Cromatografía de Gas acoplada a la Espectrometría de Masa (GC-MS), la cual es la herramienta más utilizada para analizar aromas y fragancias. Los resultados obtenidos son muy prometedores, ya que se pudieron identificar diferentes tipos de compuestos, como terpenos, cetonas, aldehídos, y principalmente ésteres, siendo el acetato de 3-metil-1-butanol y el hexanoato de etilo los de mayor abundancia relativa. Este estudio continuará hasta obtener una metodología confiable y adecuada para los propósitos antes mencionados.
Sánchez, Juan-José, College of Natural Sciences, Chemistry Department, University of Puerto Rico, Río Piedras
Synthesis and characterization of iron polymers
Two iron complexes, [Fe(vbpy)3](PF6)2 and [Fe(bpy)2(vbpy)](PF6)2, were synthesized. The [Fe(vbpy)3](PF6)2 was synthesized mixing 3:1 molar ratio of 4-vinyl-4’-methylbipyridine (vbpy) to Fe(NH4)2(SO4)2 water and precipitating with saturated KPF6 solution. To synthesize [Fe(bpy)2(vbpy)](PF6)2, a mixture 2:1 molar ratio of 2,2-bipyridine to Fe(NH4)2(SO4)2 was done in KCl solution by reflux and collected to obtain the complex Fe(bpy)2Cl2. Then, a mixture of 1:1 molar ratio of vbpy/Fe(bpy)2Cl2 was prepared and refluxed in ethanol/water (1:1) for four hours and finally precipitated in KPF6 saturated solution, to obtain [Fe(bpy)2(vbpy)](PF6)2. The complexes were characterized by FTIR, 1H-NMR and cyclic voltametry. Polymers based on each complex were synthesized to obtain Poly[Fe(vbpy)3(PF6)2] and Poly[Fe(bpy)2(vbpy)(PF6)2] following two modes: using only AIBN as initiator and combining AIBN (initiator) with TEMPO (polydispersity control). This study showed the capability of obtaining three-dimensional structures for Poly[Fe(vbpy)3(PF6)2] in comparison to Poly[Fe(bpy)2(vbpy)(PF6)2],a linear polymer. Also, a comparison between the two polymerization methods (AIBN only and AIBN/TEMPO) will be presented together with HPLC-SEC.
Valentín, Elizabeth*UPR-Río Piedras, Natural Sciences; Aponte, Myrella Cruz, Joel Fajardo, Johanna Montes, Ingrid
A Guided Inquiry Approach for Several Esterification Reaction Routes to Synthesize Artificial Flavorings
The esterification reactions have been thoroughly discussed in the undergraduate organic chemistry laboratory textbooks, but most procedures emphasize on the Fischer esterification reaction with little or no emphasis on other synthetic routes. This presentation describes an experiment using the guided inquiry approach for several esterification reaction routes to synthesize artificial flavorings. The specific objective of this experiment is to study different synthetic routes for the preparation of esters, using and integrating different esterification reactions learned throughout the Organic Chemistry course. After the laboratory experience, students will discuss the effectiveness of the reaction route. This approach will help the students to improve their ability to organize ideas and to improve integration of learned fundamental concepts and will encourage them to be creative in the solution of problems.
Pérez, Liliana*UPR-Río Piedras, Ciencias Naturales; Häggblom, Max Dept. of Biochemistry and Microbiology, Cook College-Rutgers University, NJ Kourtev, Peter Cook College-Rutgers University, NJ
Characterization of Microbial Populations in Slime Deposits from Different Paper Machines
Paper machines provide favorable conditions for microbial growth: moderate temperature, abundant nutrients and high moisture. Slime deposits formed by microbes on paper machines can cause serious problems, including paper breaks and staining, wire and felt clogging, corrosion and health hazards. Little is known about the microbial populations causing these problems. The objective of this project was to compare and identify the microbial populations of two closely positioned paper machines. We isolated colonies by cultivating dilutions of slime samples from the two machines on Plate Count Agar, Tryptic Soy Agar and Starch Agar. Isolates were streaked to ensure that they were pure cultures. Fatty acids from the pure cultures were extracted and identified by gas chromatography. Fatty acid profiles were used to identify the pure cultures using available databases. In machine 1, Bacillus genera predominated, while in machine 2 Microbacterium, Kocuria and Clavibacter genera predominated although other bacteria were present. Thus, the two machines showed different microbial populations, and machine 2 was more diverse than machine 1. In both paper machines, bacteria that had no match in the database were also found, suggesting that these may represent new bacterial species. This characterization is essential for further studies, the improvement of biocide use and for understanding the microbial community.
Renta, Isha M.*UPR-Mayagüez, Arts and Science;
General Circulations Models (GCMs)
Atmospheric models are computerized mathematical representation of dynamical, physical, chemical and radiation processes in the atmosphere. Regional Atmospheric Model System (RAMS) is a numerical prediction model designed to simulate atmospheric circulation. To simulate the climate in the future with RAMS for the transportation and concentration of contaminants and the impact it will have in Puerto Rico, it is necessary to have boundary conditions for the future. To obtain these boundary conditions we will use General Circulation Models (GCMs). GCMs are complex computer-run mathematical models that attempt to simulate the Earth’s future climate system. There are different GCMs used to simulate the atmospheric behavior. The GCM of the National Center for Atmospheric Research (NCAR), called Community Climate System Model (CCSM) will be considered for this research. CCSM is a fully coupled, global climate model that provides state-of-the-art computer simulations of the Earth's past, present, and future climate states. Its main components are the Community Atmospheric Model (CAM), the Parallel Ocean Program (POP), the Community Sea Ice Model (CSIM) and the Community Land Model (CLM).
Output data for the Caribbean Region will be obtained and compared with existing data for purposes of calibration. The focus of the analysis will be the precipitation. Sources of existing and past information such as TRMM and the Atmos web site will be described and analyzed. After obtaining reasonable agreement, the model can be used for simulating and predicting future trends, such as dryer or wetter periods.
Valentín Nieves, Julio J*UPR-Carolina, ; Peñalbert, Jose A., Mendez Tejeda, Rafael University of Florida Geography Department
Trend of Maximum and Minimum Daily Temperatures in Puerto Rico
This paper presented an analysis of monthly mean , maximum and minimum temperature variations(anomalies) for 14 stations representative of the different climatic zone of Puerto Rico. A general pattern , a negative trend in Diurnal Temperature Range (DTR ) is found. For several stations the minimum temperature has occurred at a rate two or three times than the maximum temperature during teh period (1960-200)
The behavior of temperature in this analysis confirmed the existence of the different climatic zone in Puerto Rico, the Urban Heat Island effect and Desertification effect in the Island.
Cordero, Paul* UPR-Aguadilla, Department of Natural Sciences; Gabriel, Negrón , Moraima, Castro, Tahira, Sánchez, Zoralys, Rosado, Planas, Jos M.
Isolation of
Proteins From Animal Tissue
This experiment was focused on determining the
differential expression of membrane proteins as reflected in
heart, liver, lungs, smooth muscle and kidney. In this research we
used Mus musculin (white lab mouse) as a model animal for
obtaining the different tissues. We used molecular techniques such
as: tissue disruption (mechanically and enzimatically), Sodium
Dodecyl Sulphate Poliacrylamide Gel Electrophoresis (SDS-PAGE),
densitometric analysis, spectrophotometry, and protein isolation
techniques. We found that there is a differential expression among
tissues since the electrophoretic patterns differ in number as
well as the intensity of the bands. The experiment also shows that
the enzymatic method is more efficient than the mechanical method
in the disruption of tissue as reflected by the lowerP amount of
protein degradation observed in the lanes.
Fernández-París, Marién*UPR-Río Piedras, Natural Sciences;
Efecto Inhibidor de Extractos Acuosos de Hongos en el Crecimiento de Células de Melanoma
En este estudio se utilizó la línea de células de melanoma humano (A-2058), obtenidas de una metástasis en el cerebro. El melanoma es un tipo de cáncer de los melanocitos de la piel. Las características migratorias de las células de melanoma les confieren un alto nivel de agresividad y potencial para la metástasis.
En este estudio se evaluaron extractos acuosos de los hongos Maitake y Shiitake como inhibidores de el crecimiento de las células A-2058, ya que en estudios previos se ha observado que estos hongos poseen un polisacárido (beta-1.6-glucano) con potencial anticancerígeno. Para llevar a cabo esto se preparó una infusión de 5% Hongo, luego se hicieron diluciones con el medio D-MEM-10%FBS-, logramos diferentes concentraciones (1%, 0.1% y 0.01%).
El crecimiento de las células A-2058 fue evaluado utilizando dichas concentraciones mediante una curva de crecimiento durante 7 días. El efecto de las infusiones de los hongos causó una inhibición del crecimiento de dichas células en forma de dosis-respuesta, comparado al control. La dosis de 1.0% resultó ser tóxica; la de 0.1% inhibió por un 70% y la de 0.01% por un 33%.
Estos estudios sugieren que la ingestión de estos hongos, según recomendados por naturópatas, tienen un potencial positivo para el tratamiento del cáncer. Sin embargo se debe tomar en cuenta que en altas concentraciones los mismos podrían ser tóxicos.
Rodríguez Medina, Santos*UPR-Rio Piedras, Natural Sciences/ CUH; González, Millie, L., Biology Department, University of Puerto Rico-Humacao Fuentes,Z., Geology Department, University of Puerto Rico-Mayaguez, Ramírez,W., Geology Department, University of Puerto Rico-Mayaguez, Visscher,P.T., Department of Marine Sciences, University of Conneticut-Groton, CT Casillas,L., Biology Department, University of Puerto Rico-Humacao
Microbial composition and characterization of the green layer of hypersaline mats from the Cabo Rojo Solar Salterns
To analyze the geological contributions of microorganisms in an hypersaline microbial mat, distinctive layer from the Cabo Rojo salterns mats were subjected to microscopic and geochemical analyses. Light microsocopy analysis of the top green layer revealed cyanobaterial populations from the Microcoleus and Lyngbia genus, as well diatoms was also found dominant in this layers. Even though some of the mats were covered by a salt crust of a 2mm thicknes, some of the communities still exhibits active photosysntesis. Interestingly, our minerological analyse also detected a layering in the minerals of the mats. Our next step will be study the activities of the different biological communities, their contributions to the formation of these minerals and their quantification.
Sueiro Lilly, Ann*UPR-Rio Piedras, School of Family Ecology and Nutrition; Rivera, Sharon, College of Natural Sciences, UPR Guerrero, Ricardo, O. School of Pharmacy, MSC, UPR Arciniega, Minarda de la O. Licenciatura de Farmacia, Universidad Autnoma del Estado de Hidalgo
Biological Activities of Twelve Medical Plant Extracts from México
In the past twenty years, there has been a tremendous worldwide growth of interest in herbal remedies. Mexico possesses an extraordinary biodiversity and most of the population regularly uses plant remedies. The objective was to analyze several bioactivities from twelve plant extracts of the State of Hidalgo. 1. The brine shrimp lethality test (BSLT) capable of detecting a broad spectrum of bioactivities. 2. The antioxidant activity was assessed with DPPH stable free radical. 3. The $-glucosidase inhibition that recognizes potential anti-AIDS or anti-diabetes compounds. 4. The xanthine oxidase inhibition that identifies anti-gout metabolites, and 5. the antibacterial activity that measures the antibiotic strength of the extracts constituents. The extract of Caesalpinia pulcherrima demonstrated the best activity in the BSLT with a LC50 1.06 :g/mL. The methanolic extract of Stevia pilosa presented the best free radical scavenging activity with an ED50 6.65 :g/mL. The same extract proved to have the greatest $-glucosidase inhibition percentage: 87.68%. None of the extracts seemed to be active in the xanthine oxidase inhibition procedure. Finally, in the antibacterial assay, the methanolic extract of Gnaphalium inornatum inhibited the growth of Corynebacterium diphteriae. These results suggest the presence of active metabolites. It is proposed that further investigation should be conducted to identify the chemical structure of the active compounds.
Valentín, Anibal*UPR-Aguadilla, Departamento de Ciencias Naturales;Nikaury, Rivera
Marcadores Séricos en pacientes con el Síndrome de Apnea de Sueño
Apnea del sueño es una condición que se caracteriza por interrupciones en los patrones respiratorios durante el sueño. Estas interrupciones pueden ser moderadas o severas y hasta causar la muerte al paciente. En Puerto Rico, la incidencia de esta condición ha aumentado significativamente durante los últimos diez años. Actualmente, no se conoce cura para esta condición y se diagnostica mediante la polisomnografía, un procedimiento costoso, tedioso y que consume mucho tiempo. Estudios previos han demostrado que durante ataques de apnea, los niveles de algunos marcadores séricos como el IgG, Tumor Necrosis Factor, Epidermal Growth Factor entre otros son afectados. ¿Podrá ser posible correlacionar los niveles de esos marcadores séricos con la condición de apnea, y a su vez utilizarlos como indicadores de la misma? Consideramos que la posibilidad de que esto pueda ser cierto, es real. Para tratar de contestar estas interrogantes, recolectamos muestras de sangre de pacientes que presentan la condición de apnea y que han sido previamente diagnosticados con la misma. Estas muestras fueron procesadas y separadas en sus componentes básicos (RBC, WBC y plasma) con el propósito de aislar los marcadores séricos de nuestro interés y por medio de SDS- PAGE, análisis de patrones electroforéticos y Western Blot establecer alguna correlación entre la apnea y la concentración de estos marcadores, que nos sirva como un mecanismo diagnóstico. Hasta el presente, hemos identificado variaciones en los patrones electroforéticos entre pacientes que padecen la condición vs. los pacientes controles.