The Use of Mucoadhesive Polymers to Enhance the Hypotensive Effect of a Melatonin Analogue, 5-MCA-NAT, in Rabbit Eyes

Purpose.: 5-Methoxy-carbonylamino-N-acetyltryptamine (5-MCA-NAT, a melatonin receptor agonist) produces a clear intraocular pressure (IOP) reduction in New Zealand White rabbits and glaucomatous monkeys. The goal of this study was to evaluate whether the hypotensive effect of 5-MCA-NAT was enhanced by the presence of cellulose derivatives, some of them with bioadhesive properties, as well as to determine whether these formulations were well tolerated by the ocular surface. Methods.: Formulations were prepared with propylene glycol (0.275%), carboxymethyl cellulose (CMC, 0.5% and 1.0%) of low and medium viscosity and hydroxypropylmethyl cellulose (0.3%). Quantification of 5-MCA-NAT (100 μM) was assessed by HPLC. In vitro tolerance was evaluated by the MTT method in human corneal-limbal epithelial cells and normal human conjunctival cells. In vivo tolerance was analyzed by biomicroscopy and specular microscopy in rabbit eyes. The ocular hypotensive effect was evaluated measuring IOP for 8 hours in rabbit eyes. Results.: All the formulations demonstrated good in vitro and in vivo tolerance. 5-MCA-NAT in CMC medium viscosity 0.5% was the most effective at reducing IOP (maximum IOP reduction, 30.27%), and its effect lasted approximately 7 hours. Conclusions.: The hypotensive effect of 5-MCA-NAT was increased by using bioadhesive polymers in formulations that are suitable for the ocular surface and also protective of the eye in long-term therapies. The use of 5-MCA-NAT combined with bioadhesive polymers is a good strategy in the treatment of ocular hypertension and glaucoma.

Estudio de márgenes tras tumorectomía seguida de radiofrecuencia en cirugía conservadora del cáncer de mama

Introducción: La cirugía conservadora constituye hoy el tratamiento estándar en el ca. mama. La recurrencia local debe evitarse en la medida de lo posible, en tanto en cuanto condiciona un mayor estrés para la paciente, la obligatoriedad de tratamientos más agresivos, y una disminución de la supervivencia. Para ello, la obtención de márgenes libres es un factor clave. Pese a todos los esfuerzos por obtener dichos márgenes libres en un único acto quirúrgico, sigue existiendo una alta tasa de reintervenciones para su obtención. La ARF es un procedimiento aún en investigación sobre la que existen pocos datos relativos a los detalles de la técnica y su reproductibilidad, así como su eficacia en la obtención de márgenes libres y menos aún sobre persistencia de enfermedad, recurrencia local y repercusión sobre la supervivencia, para lo que se necesitaran estudios con amplios grupos de pacientes y tiempo de seguimiento. Nosotros nos proponemos aportar datos relativos a la ARF, centrados en un protocolo de la técnica de aplicación de la ARF, valoración de la utilidad de la ARF en la obtención de margen libres y repercusión de la ARF sobre las complicaciones y el resultado estético. Material y métodos: Estudio longitudinal de una cohorte prospectiva a las que se le realiza cirugía conservadora seguida de radiofrecuencia, y una cohorte retrospectiva a las que se le realiza cirugía conservadora sin aplicación de radiofrecuencia. Análisis descriptivo de los resultados y comparativo del grupo a estudio respecto a grupo control. Resultados: Se ha realizado ARF a un total de 14 pacientes, con el empleo de un terminal de electrodo simple, lo que aporta gran versatilidad y reproducibilidad a la técnica, y obteniendo un 100% de márgenes libres. Se ha registrado una reintervención por microcalcificaciones evidenciadas en mamografía de control. No se han registrado complicaciones específicas de la técnica. Se han obtenido un total de 92,8% de resultados buenos ó excelentes. En el análisis comparativo, no se han encontrado diferencias estadísticamente significativas respecto a tasa de reintervenciones, resultados cosméticos ó complicaciones. Conclusiones: 1. La ARF ha demostrado en el grupo de estudio una eficacia del 100% en relación con negatividad o no viabilidad de células tumores en todos los márgenes extirpados. 2. La ARF contribuye a aumentar el margen quirúrgico oncológico de seguridad en cirugía conservadora del cáncer de mama, hecho de especial interés en subgupos de mayor riesgo de recurrencia local. 3. La ARF ha demostrado ser una técnica segura con una tasa de complicaciones generales similares al tratamiento estándar, no existiendo en nuestra serie ninguna complicación específica atribuible a la técnica. 4. La elección del terminal con electrodo simple nos permite mayor versatilidad, adaptando el procedimiento y técnica quirúrgica según el tamaño de la lesión para conseguir el efecto deseado. 5. Asimismo la utilización del terminal con electrodo simple nos permite ampliar indicaciones de la ARF al poder incluir lesiones cercanas a piel y pectoral sin riesgo de quemaduras. 6. La aplicación de radiofrecuencia en márgenes y su exéresis no ha afectado el resultado cosmético.

Diadenosine Polyphosphates in Tears of Sjögren Syndrome Patients

Purpose.: To analyze the levels of diadenosine tetraphosphate (Ap4A) and diadenosine pentaphosphate (Ap5A) in tears of subjects with Sjögren syndrome and to compare them with those in a control group. Methods.: Twelve subjects with a diagnosis of Sjögren syndrome and 20 healthy control subjects were invited to participate in the present study. Schirmer strips were used to measure tear secretion (Schirmer I test) and to collect tears. Ap4A and Ap5A were measured by high-pressure liquid chromatography (HPLC), and a dry eye questionnaire (DEQ) was used to evaluate dry eye symptomatology. Results.: The mean concentrations of Ap4A and Ap5A in the Sjögren syndrome group were 2.54 ± 1.02 and 26.13 ± 6.95 μM, respectively. This group of patients was divided in two subgroups: four patients with normal tear production and eight patients with low tear production. Concentrations of Ap4A, and Ap5A in patients with normal tear production (Schirmer test result, 12.3 ± 1.2 mm) were 0.47 ± 0.20 and 8.03 ± 3.27 μM, respectively. In the patients with low tear production (Schirmer test result, 1.0 ± 0.3 mm), the concentrations were 4.09 ± 1.36 and 39.51 ± 8.46 μM, respectively and in the control group, 0.13 ± 0.03 and 0.04 ± 0.02 μM, respectively. Conclusions.: Patients with Sjögren syndrome have abnormally elevated concentrations of diadenosine polyphosphates, indicating that these compounds could be used in the diagnosis of this disease.

Dual Roles of Diadenosine Polyphosphates in Corneal Epithelial Cell Migration

Purpose. To investigate the influence of diadenosine polyphosphates on the rate of corneal epithelial cell migration. Methods. Primary corneal epithelial cell cultures were obtained from New Zealand White rabbits. Immunocytochemical experiments were performed by fixing the cells with 4% paraformaldehyde (PFA) and incubated with cytokeratin 3 primary antibody, which was subsequently incubated with a secondary IgG mouse labeled with FITC, and the cells were observed under confocal microscopy. Migration studies were performed by taking confluent monolayers that were wounded with a pipette tip and challenged with different di- and mononucleotides with or without P2 antagonist (n = 8 each treatment). For concentration–response analysis, compounds were tested in doses ranging from 10−8 to 10−3 M (n = 8). The stability of the dinucleotides was assayed by HPLC, with an isocratic method (n = 4). Results. Cells under study were verified as corneal epithelial cells via the immunocytochemical analysis. Cell migration experiments showed that Ap4A, UTP, and ATP accelerated the rate of healing (5, 2.75, and 3 hours, respectively; P < 0.05; P < 0.001), whereas Ap3A, Ap5A, and UDP delayed it (6.5, 10, and 2 hours, respectively; P < 0.05). ADP did not modify the rate of migration. Antagonists demonstrated that Ap4A and Ap3A did activate different P2Y receptors mediating corneal wound-healing acceleration and delay. Concerning the possible degradation of the dinucleotides, it was almost impossible to detect any products resulting from their cleavage. Conclusions. Based on the pharmacological profile of all the compounds tested, the two main P2Y receptors that exist in these corneal cells are a P2Y2 receptor accelerating the rate of healing and a P2Y6 receptor that delays this process.

Design and synthesis of novel quinolones directed to the Plasmodium falciparum bc1 protein complex

Tese de Doutoramento, Química, Especialização em Química Orgânica, Faculdade de Ciências e Tecnologia, Universidade do Algarve, 2016

Photocatalytic Dehydrogenative Lactonization of 2-Arylbenzoic Acids

A metal-free dehydrogenative lactonization of 2-arylbenzoic acids at room temperature was developed. This work illustrates the first application of visible-light photoredox catalysis in the preparation of benzo-3,4-coumarins, an important structural motif in bioactive molecules. The combination of photocatalyst [Acr+-Mes] with (NH4)2S2O8 as a terminal oxidant provides an economical and environmentally benign entry to different substituted benzocoumarins. Preliminary mechanistic studies suggest that this reaction most likely occurs through a homolytic aromatic substitution pathway.

On the reactivity of naphthalene and biphenyl dianions: tying up loose ends concerning an SN2-ET dichotomy in alkylation reactions

Naphthalene and biphenyl dianions are interesting compounds that can be obtained by double reduction of the corresponding arenes in solution with certain alkali metals. These dianions are highly reactive and rather elusive species with very high laying and highly delocalized electrons. They share many aspects of the reactivity of the alkali metal they originated from and consequently behave primarily as strong electron transfer (ET) reagents. We report here kinetic evidence for a different type of reactivity in their alkylation reactions with alkyl fluorides. By using cyclopropylmethyl fluoride (c-C3H5CH2F) as a very fast radical probe, we were able to settle that this alkylation does not involve the classical electron transfer reaction followed by radical coupling between diffusing radicals, but supports the alternative SN2 concerted mechanism, discerning thus this mechanistic SN2-ET dichotomy.

A comparative study of hydroxyl- and carboxylate-functionalized imidazolium and benzimidazolium salts as precursors for N-heterocyclic carbene ligands

The preparation of imidazolium and benzimidazolium salts with hydroxyl or carboxylate functions has been achieved using straightforward synthetic pathways. These salts in combination with palladium(II) acetate give active catalytic systems for Suzuki reaction. A comparative study has been performed, which has revealed that both the heterocycle and the functional group are important for the catalytic activity and stability of the catalyst.

Synthesis of 3,5-Disubstituted Isoxazoles and Isoxazolines in Deep Eutectic Solvents

The synthesis of different 3,5-disubstituted isoxazoles and related isoxazolines using choline chloride:urea as deep eutectic solvent (DES) in a one-pot three step reaction has been accomplished successfully. The use of highly nucleophilic functionalized DES did not affect the process where highly electrophilic reagents or intermediates are involved. The presence of DES showed to be essential since the reaction in absence of this media did not proceed. The DES media could be reused up to five times without a detrimental effect on the yield of the reaction. To exemplify the synthetic potential of this methodology, the reaction was scaled up to the gram scale without any noticeable problem. Finally, different isoxazoles were easily transformed into β-aminoenones.

Reduction of 1,2-dicarbonyl compounds and of their N-phenylimine derivatives by sodium cyanide under aprotic conditions

Some aromatic 1,2-dicarbonyl compounds, i.e. 9,10-phenanthrenequinone, acenaphthenequinone and benzil, and their corresponding N-phenyl monoimines, have been reduced, using dry acetonitrile as the solvent, in the presence of sodium cyanide as a reducing agent. Comparative potentiostatic preparative-scale electrolysis is described.

Direct synthesis of β-ketophosphonates and vinyl phosphonates from alkenes or alkynes catalyzed by CuNPs/ZnO

Copper nanoparticles (CuNPs) supported on ZnO have been shown to effectively catalyze the direct synthesis of β-ketophosphonates from alkenes or alkynes, and that of vinyl phosphonates from alkynes and diethylphosphite, under air and in the absence of any additive or ligand. When using alkynes as starting materials, the selectivity proved to be dependent on the nature of the alkyne. Thus, alkynes conjugated with an aromatic ring or a carbon–carbon double bond gave β-ketophosphonates as the main reaction products, whereas aliphatic alkynes or alkynes conjugated with a carbonyl group led to the formation of the corresponding vinyl phosphonates.

Copper Nanoparticles in Click Chemistry

Conspectus: The challenges of the 21st century demand scientific and technological achievements that must be developed under sustainable and environmentally benign practices. In this vein, click chemistry and green chemistry walk hand in hand on a pathway of rigorous principles that help to safeguard the health of our planet against negligent and uncontrolled production. Copper-catalyzed azide–alkyne cycloaddition (CuAAC), the paradigm of a click reaction, is one of the most reliable and widespread synthetic transformations in organic chemistry, with multidisciplinary applications. Nanocatalysis is a green chemistry tool that can increase the inherent effectiveness of CuAAC because of the enhanced catalytic activity of nanostructured metals and their plausible reutilization capability as heterogeneous catalysts. This Account describes our contribution to click chemistry using unsupported and supported copper nanoparticles (CuNPs) as catalysts prepared by chemical reduction. Cu(0)NPs (3.0 ± 1.5 nm) in tetrahydrofuran were found to catalyze the reaction of terminal alkynes and organic azides in the presence of triethylamine at rates comparable to those achieved under microwave heating (10–30 min in most cases). Unfortunately, the CuNPs underwent dissolution under the reaction conditions and consequently could not be recovered. Compelling experimental evidence on the in situ generation of highly reactive copper(I) chloride and the participation of copper(I) acetylides was provided. The supported CuNPs were found to be more robust and efficient catalyst than the unsupported counterpart in the following terms: (a) the multicomponent variant of CuAAC could be applied; (b) the metal loading could be substantially decreased; (c) reactions could be conducted in neat water; and (d) the catalyst could be recovered easily and reutilized. In particular, the catalyst composed of oxidized CuNPs (Cu2O/CuO, 6.0 ± 2.0 nm) supported on carbon (CuNPs/C) was shown to be highly versatile and very effective in the multicomponent and regioselective synthesis of 1,4-disubstituted 1,2,3-triazoles in water from organic halides as azido precursors; magnetically recoverable CuNPs (3.0 ± 0.8 nm) supported on MagSilica could be alternatively used for the same purpose under similar conditions. Incorporation of an aromatic substituent at the 1-position of the triazole could be accomplished using the same CuNPs/C catalytic system starting from aryldiazonium salts or anilines as azido precursors. CuNPs/C in water also catalyzed the regioselective double-click synthesis of β-hydroxy-1,2,3-triazoles from epoxides. Furthermore, alkenes could be also used as azido precursors through a one-pot CuNPs/C-catalyzed azidosulfenylation–CuAAC sequential protocol, providing β-methylsulfanyl-1,2,3-triazoles in a stereo- and regioselective manner. In all types of reaction studied, CuNPs/C exhibited better behavior than some commercial copper catalysts with regard to the metal loading, reaction time, yield, and recyclability. Therefore, the results of this study also highlight the utility of nanosized copper in click chemistry compared with bulk copper sources.

Ligand-Free Palladium-Catalyzed Oxyarylation of Dihydronaphthal­enes and Chromenequinone with o-Iodophenols and 3-Iodolawsone in PEG-400: An Efficient Synthesis of 5-Carbapterocarpans and Pterocarpanquinones

Dihydronaphthalenes were oxyarylated with o-iodophenols, in PEG-400 at 140 or 170 °C, leading regio- and stereoselectively to 5-carbapterocarpans. By using Pd(OAc)2 (5–10 mol%) as precatalyst and Ag2CO3 (1.1 equiv) as base (conditions A), products were obtained in good to excellent chemical yields, in 5–30 minutes, irrespective of the pattern of substitution the starting materials. Alternatively, when p-hydroxyacetophenone oxime derived palladacycle (1 mol%) was used as precatalyst, and dicyclohexylamine (2 equiv) was used as base (silver-free, conditions B), the corresponding adducts were obtained in moderate to good yields, in 0.5 to 4 hours. Finally, the oxyarylation of dihydronaphthalenes­ and chromenquinone with o-iodophenols and 3-iodolawsone in PEG-400 under conditions A led regio- and stereoselectively to the formation of carbapterocarpanquinones and pterocarpanquinones in moderate yield.

Remote Substituent Effects on the Stereoselectivity and Organocatalytic Activity of Densely Substituted Unnatural Proline Esters in Aldol Reactions

The organocatalytic activities of highly substituted proline esters obtained through asymmetric [3+2] cycloadditions of azomethine ylides derived from glycine iminoesters have been analyzed by 19F NMR and through kinetic isotope effects. Kinetic rate constants have been determined for unnatural proline esters incorporating different substituents. It has been found that exo-L and endo-L unnatural proline methyl esters yield opposite enantiomers in aldol reactions between cyclic ketones and aromatic aldehydes. The combined results reported in this study show subtle and remote effects that determine the organocatalytic behavior of these synthetic but readily available amino acid derivatives. These data can be used as design criteria for the development of new pyrrolidine-based organocatalysts.