Now showing items 1-20 of 106

    • 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 ...
    • 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 ...
    • Pastene, Edgar; Gómez, Maritza; Speisky Cosoy, Hernán; Núñez Vergara, Luis (Sociedade Brasileira de Quimica, 2009)
      An apparatus which allows the direct measurement of the antioxidant capacity of volatiles compounds emitted from some herbs and culinary spices is described. The device comprises: a sample chamber, a mixing chamber, a pump ...
    • 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, ...
    • Álvarez Lueje, Alejandro; Núñez Vergara, Luis; Vicuna,; Squella Serrano, Juan (1996)
      The electrochemical oxidation of acyclovir at different pH and concentrations using both differential pulse and cyclic voltammetry was studied. Acyclovir exhibits one differential pulse voltammetric peak at the glassy ...
    • 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, ...
    • Squella Serrano, Juan; Silva,; Núñez Vergara, Luis (1981)
      The hydrolysis of flucloxacillin at pH 4.9 yields a degradation product which is polarographically oxidizable. This derivative has not been identified, but would seem to contain a thiol group. It gives a diffusion-controlled ...
    • 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 ...
    • Núñez Vergara, Luis; Squella Serrano, Juan; Navarrete Encina, Patricio; Vicente-García, E.; Preciado, S.; Lavilla, R. (2011)
      Chromenopyridines constitute a structurally diverse class of compounds with a wide range of bioactivities and increasing presence in drugs. Here we analyze the scope of the synthetic methodology to access this nucleus with ...
    • 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 ...
    • Squella Serrano, Juan; Mosre, J.; Blázquez, M.; Núñez Vergara, Luis (1991)
      Electrochemical studies on nitrendipine using mixed aqueous/dimethylformamide (DMF) solvent have allowed us to generate the one-electron reduction product, the nitro radical anion, RNO.-2. The voltammetric technique has ...