Resumo

VARGAS, F et al. In vitro studies of the dual properties of Allopurinol anti- and photo-oxidants Mechanisms. Rev. colomb. cienc. quim. farm. [online]. 2008, vol.37, n.1, pp.69-83. ISSN 0034-7418.

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.

Palavras-chave : Allopurinol; antioxidant; chemiluminescence; photo-oxidant; reactive oxygen species.

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