Now showing items 1-20 of 74

    • Núñez Vergara, Luis; Donoso, G.; Roman, A.; Squella Serrano, Juan (1988)
      The apparent permeation rate constants and amount of ranitidine transferred in 1 h were measured through everted rat intestine using a perfusion apparatus. The effects of pH and 5% or 10% ethanol on the apparent permeation ...
    • Squella Serrano, Juan; Solabarrieta, C.; Núñez Vergara, Luis (1993)
      The cyclic voltammetric behaviour of nifedipine was studied. The addition of three aprotic solvents to nifedipine in an aqueous citrate buffer system was examined. Qualitatively they result in separation of the initial ...
    • Squella Serrano, Juan; Zanocco, A.; Perna, S.; Núñez Vergara, Luis (1990)
      Nitrendipine produces a well-defined polarographic peak due to the four-electron reduction of the nitro group. This peak is used for tracking the photodecomposition of nitrendipine in both UV light and daylight conditions. ...
    • Moscoso Cabello, Raúl Andrés; Carbajo, J.; López, M.; Núñez Vergara, Luis; Squella Serrano, Juan (ELSEVIER SCIENCE INC, 2011-02)
      We report that GCE modified with MWCNTs can be derivatized by the nitroaromatic drug nitrendipine (NTD) ((RS)-ethyl methyl 2,6-dimethyl-4-(3-nitrophenyl)-1,4-dihydropyridine-3,5-dicarboxylate) simply by dipping the electrode ...
    • Speisky Cosoy, Hernán; Squella Serrano, Juan; Núñez Vergara, Luis (1991)
      Boldine shows a concentration-dependent relaxation effect on the rat ileum preparation with a pD2 of 3.77 ± 0.12. The alkaloid also produces a concentration-dependent parallel shift of the curve-response to acetylcholine, ...
    • Jara Ulloa, Paola Andrea; Cañete Rosales, Paulina; Núñez Vergara, Luis; Squella Serrano, Juan (2011)
      1-Methyl-4-nitro-2-brominemethylimidazole (4-NimMeBr), was electrochemically reduced on mercury, glassy carbon and multiwalled carbon nanotubes (MWCNT) modified electrodes. 4-NimMeBr was adsorbed on the MWCNT modified ...
    • Squella Serrano, Juan; Núñez Vergara, Luis (1982)
      The electroactivity of a degradation product from penicillin V is described.This electroactive product is formed by acidic hydrolysis at pH 4.0 and heating at 90QC for 60 minutes. This derivative has not been identified, ...
    • Gunckel Ulisse, María Soledad; Santander Gutiérrez, Ingrid Paola; Cordano, G.; Ferreira Parker, Jorge; Muñoz, S.; Núñez Vergara, Luis; Squella Serrano, Juan (ELSEVIER SCI IRELAND, 1998-07-03)
      The electron-donating ability of gallates, which are food and pharmaceutical antioxidants, is quantitatively assessed on the basis of their electrochemical characteristics. Gallic acid and the propyl, i-propyl, butyl, ...
    • Díaz Araya, Guillermo; Godoy, L.; Naranjo, L.; Squella, A.; Letelier, M. E.; Núñez Vergara, Luis (1998)
      Lipid peroxidation in rat brain slices was induced by Fe+3/ascorbate.Brain lipid peroxidation, as measured by malondialdehyde formation, was inhibited by all the tested nitro aryl 1,4-dihydropyridine derivatives over a ...
    • Squella Serrano, Juan; Núñez Vergara, Luis (1984)
      The isolation and identification of a cathodic degradation product from cephradine after acidic hydrolysis in presence of 1 % formaldehyde is reported. Also, the electroacti vity of an anodic degradation product is described. ...
    • Squella Serrano, Juan; Pezzani, M.; Cassels Niven, Bruce; Aillón Torres, Milton; Rezende, Marcos; Núñez Vergara, Luis (1992)
      The amphetamine derivative 4,5‐dimethoxy‐2‐nitrophenyl‐2‐aminopropane, a positional isomer of the potent hallucinogen DON, was studied by cyclic voltammetry and polarography. The nitro compound was reduced to the corresponding ...
    • Bollo Dragnic, Soledad; Yáñez Soto, Claudia; Sturm Schaub, Juan; Núñez Vergara, Luis; Squella Serrano, Juan (AMER CHEMICAL SOC, 2003-04-15)
      Potassium ferricyanide ([Fe(CN)(6)](3-)) reduction and ferrocenemethanol (Fe-OH) oxidation at a beta-cyclodextrin (beta-CD)-modified gold electrode were investigated by cyclic voltammetry (CV) and scanning electrochemical ...
    • Bollo Dragnic, Soledad; Yáñez, Claudia; Sturm, Juan; Núñez Vergara, Luis; Squella Serrano, Juan (2003)
      Potassium ferricyanide (Fe(CN)6]3-) reduction and ferrocenemethanol (Fc-OH) oxidation at a β-cyclodextrin (β-CD)-modified gold electrode were investigated by cyclic voltammetry (CV) and scanning electrochemical microscopy ...
    • Ortiz,; Núñez Vergara, Luis; Squella Serrano, Juan (2002)
      We have studied the O2/O2·- redox couple on the HMDE in DMSO aprotic media, obtaining optimal conditions of both oxygen concentration and scan rate in order to avoid oscillatory phenomena. By choosing the oxygen concentration ...
    • Bollo Dragnic, Soledad; Núñez Vergara, Luis; Squella Serrano, Juan (1999)
      Cyclic voltammetry (CV) and digital simulation methods are utilized to elucidate the mechanism of electrochemical reduction of a series of nitro aryl 1,4-dihydropyridines in protic (aqueous) and mixed media. The experimental ...
    • Mozo, J. D.; Carbajo, J.; Sturm Schaub, Juan; Núñez Vergara, Luis; Salgado, P.; Squella Serrano, Juan (Wiley, 2012)
      A new, sensitive, reproducible and easy-to-use flow-injection method for determining nifuroxazide based on adsorptive stripping linear sweep voltammetry over screen-printed carbon electrodes is presented. The presented ...
    • Yáñez,; Núñez Vergara, Luis; Squella Serrano, Juan (2002)
      Carbon paste electrodes modified with β-cyclodextrin have been investigated for voltammetric determination of nitrendipine. The immobilization of the β-cyclodextrin on the carbon paste leads to a modification of the electrode ...
    • Yáñez, C.; Núñez Vergara, Luis; Squella Serrano, Juan (2003)
      The formation of inclusion complexes of well-known 1,4-dihydropyridine calcium antagonists, such as nifedipine (NF) and nicardipine (NC), with beta-cyclodextrin (betaCD) was investigated by differential pulse polarography ...
    • Núñez Vergara, Luis; Pardo Jiménez, V; Barrientos, C.; Olea Azar, Claudio; Navarrete-Encina, P. A.; Squella Serrano, Juan (2012)
      In this study, two series of dihydropyridine-fused and pyridine-fused coumarins were synthesised and electrochemically characterised in aprotic medium. In both series, the most easily reducible groups were the endocyclic ...
    • Maya Arango, Juan; Morello Casté, Antonio; Repetto Scaramelli, Yolanda; Tellez Neubauer, Rowena; Rodríguez, A.; Zelada, U.; Puebla, P.; Caballero S., Esther; Medarde, M.; Núñez Vergara, Luis; Squella Serrano, Juan; Bontá, M.; Bollo Dragnic, Soledad; Feliciano M., Arturo San (PERGAMON-ELSEVIER SCIENCE, 2000-01)
      A series of 3-chloro-phenyl-1,4-dihydropyridine derivatives produced different degrees of inhibition of parasite growth and respiration on clone Brener, LQ and Tulahuen strains of Trypanosome cruzi epimastigotes. Respiratory ...