Studies of the photooxidant properties of antibacterial fluoroquinolones and their naphthalene derivatives.

We synthesized and determined the production of reactive oxygen species (ROS) as 1O2, *-O2, *OH, H2O2 during the photolysis with UV-A light of three antibacterial quinolones and their naphthyl ester derivatives. Singlet oxygen and ROS dose-dependant generation from norfloxacin (1), enoxacin (2), ciprofloxacin (3) and their respective naphthyl ester derivatives 4-6 were detecting in cell-free systems by the histidine assay and by luminol-enhanced chemiluminescence (LCL). Both the electronic absorption and emission spectra were quantified and their photostability determined. The antibacterial activity in darkness and under irradiation of compounds 4, 5 and 6 was tested on E. coli and compared with their parent drugs.

In vitro studies of the dual properties of Allopurinol anti- and photo-oxidants Mechanisms / Estudio in vitro de dos propiedades del Alopurinol.

The objective of this study was to investigate the ability of allopurinol (1) to inhibit free radical or reactive oxygen species (.OH, ¹O2, H2O2) as well as the study of its photochemical activity. We investigated the ability of 1 to scavenge oxygen metabolites generated by cell-free systems using luminol enhanced-chemiluminescence and electronic absorption spectra as monitors. Both absorbance and fluorescence scans reveal that 1 is able to react with equimolar quantities of H2O2. In the presence of 1 a dose-dependent inhibition period was observed in this system as assayed by isoluminol-enhanced chemiluminescence (ILCL) in the presence of horseradish peroxidase (HRP), as well as by luminol-enhanced chemiluminescence (LCL) in the presence of H2O2 or ferrous ion. On the other hand, 1 did not show an efficient scavenging activity of galvanoxyl radical in ethanolic solutions. Furthermore, in a separate experiment, it was not observed trapping of singlet oxygen (¹O2) generated by Rose Bengal, in the presence of 1. The activity of 1 was compared with that of vitamins E and C. In vitro experiments of photohemolysis in presence of 1 and cinoxacin, a phototoxic antibacterial quinolone, the photohemolytic effect of cinoxacin was diminished. Allopurinol alone did not show any phototoxic effect under irradiation with UV-A or visible light but was photo-unstable and phototoxic in vitro with UV-B light.

Se estudió la habilidad del alopurinol (1) para inhibir radicales libres o especies reactivas de oxigeno (.OH, ¹O2, H2O2), igualmente se determinó su actividad fotoquímica. De otro lado se midió la habilidad de 1 para eliminar los metabolitos de oxígeno generados por un sistema libre de células basado en quimioluminicencia aumentada de luminol y se monitoreo el espectro de absorción electrónica. Las dos determinaciones, absorbancia y fluorescencia, revelan que 1 es capaz de reaccionar con cantidades equimoleculares de H2O2. En presencia de alopurinol se observan periodos de inhibición dosis dependiente al usar isoluminol como intensificador de luminiscencia (ILCL) en presencia de peroxidasa de rábano o ión ferroso. Por otro lado, 1 no mostró una eficiente actividad frente a radicales galvanoxil en solución etanólica. En otros experimentos en presencia de 1 no se observó bloqueo de especies de oxígeno singlete (¹O2) generado por rosa bengala. La habilidad de 1 fue comparada con la de vitaminas E y C. En experimentos de fotohemólisis in vitro en presencia de 1 y cinoxacin, quinolona fototóxico antibanterial, el efecto fotohemolítico del cinoxacin fue disminuido. El alopurinol no mostró efecto fototóxico por irradiación con luz UV-A o luz visible, sin embargo se mostró foto - inestable y fototóxico in vitro bajo irradiación con luz UV-B.