Scavenging of photogenerated ROS by Oxicams. Possible biological and environmental implications

GABRIELA V. FERRARI; JOSÉ NATERA; M. PAULINA MONTAÑA; VANESA MUÑOZ; EDUARDO L. GUTIÉRREZ; WALTER MASSAD; SANDRA MISKOSKI; NORMAN A. GARCÍA

JOURNAL OF PHOTOCHEMISTRY AND PHOTOBIOLOGY B-BIOLOGY

ELSEVIER SCIENCE SA

Año: 2015 vol. 153 p. 233 - 239

1011-1344

The profusely employed drugs Piroxicam (Piro), Tenoxicam(Teno) and Meloxicam (Melo) belonging to the nonsteroidal antiinflammatory drug (NSAID) family of the Oxicams (Oxis) were studied in the frame of two specific conditions: (a) their ROS scavenging ability, in relation to a possible biological antioxidant action and (b) their photodegradability under environmental conditions, in the context of Oxi-contaminated waters.Singletmolecular oxygen (O2(1Δg)) and superoxide radical anion (O2 ?−)were photogenerated through Riboflavin (Rf, vitamin B2)-photosensitization in aqueous and aqueous-methanolic solutions in the presence of Oxi concentrations in the range 50?500 μM. The visible-light absorber vitamin is currently present in all types of naturalwaters and constitutes themost frequent endogenous photosensitizer inmammals. Hence, itwasemployed in order to mimic both natural sceneries of interest.All three Oxis quench O2(1Δg) with rate constants in the order of 108 M−1 s−1 showing a significant photodegradation efficiency given by a dominant reactive fashion for deactivation of the oxidative species. Although this is not a desirable property in the context of photoprotection upon prolonged photoirradiation, constitutes in fact a promissory aspect for the degradation NSAIDs, in waste waters. Indirect evidence indicates that Melo is also oxidized through a O2 ?−-mediated component.The simultaneous presence of Piro plus tryptophan or tyrosine under Rf-photosensitizing conditions, which has taken the amino acids as photooxidizable model residues in a proteinaceous environment, indicates that the NSAID induces a protection of the biomolecules against photodynamic degradation.