title: Scavenging of photogenerated ROS by Oxicams. Possible biological and environmental implications.
abstract: The profusely employed drugs Piroxicam (Piro), Tenoxicam (Teno) and Meloxicam (Melo) belonging to the non-steroidal 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. Singlet molecular oxygen (O2((1)Δg)) 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 natural waters and constitutes the most frequent endogenous photosensitizer in mammals. Hence, it was employed in order to mimic both natural sceneries of interest. All three Oxis quench O2((1)Δg) with rate constants in the order of 10(8)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.
authors.affiliation: Area de Química Física, Universidad Nacional de San Luis, 5700 San Luis, Argentina.
authors.forename: Gabriela V
authors.initials: GV
authors.lastname: Ferrari
authors.affiliation: Departamento de Química, Universidad Nacional de Río Cuarto, 5800 Río Cuarto, Argentina.
authors.forename: José
authors.initials: J
authors.lastname: Natera
authors.affiliation: Area de Química Física, Universidad Nacional de San Luis, 5700 San Luis, Argentina.
authors.forename: M
authors.initials: M
authors.lastname: Paulina Montaña
authors.affiliation: Area de Química Física, Universidad Nacional de San Luis, 5700 San Luis, Argentina.
authors.forename: Vanesa
authors.initials: V
authors.lastname: Muñoz
authors.affiliation: Area de Química Física, Universidad Nacional de San Luis, 5700 San Luis, Argentina.
authors.forename: Eduardo L
authors.initials: EL
authors.lastname: Gutiérrez
authors.affiliation: Departamento de Química, Universidad Nacional de Río Cuarto, 5800 Río Cuarto, Argentina.
authors.forename: Walter
authors.initials: W
authors.lastname: Massad
authors.affiliation: Departamento de Química, Universidad Nacional de Río Cuarto, 5800 Río Cuarto, Argentina.
authors.forename: Sandra
authors.initials: S
authors.lastname: Miskoski
authors.affiliation: Departamento de Química, Universidad Nacional de Río Cuarto, 5800 Río Cuarto, Argentina. Electronic address: ngarcia@exa.unrc.edu.ar.
authors.forename: Norman A
authors.initials: NA
authors.lastname: García
mesh_terms: D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000737:chemistry; D016166:Free Radical Scavengers / Q000737:chemistry*; D008027:Light; D000077239:Meloxicam; D010084:Oxidation-Reduction; D010782:Photolysis / Q000528:radiation effects; D010894:Piroxicam / Q000031:analogs & derivatives* / Q000737:chemistry*; D011725:Pyridines / Q000737:chemistry; D017382:Reactive Oxygen Species / Q000737:chemistry*; D012235:Rhodamines / Q000737:chemistry; D012256:Riboflavin / Q000737:chemistry; D026082:Singlet Oxygen / Q000737:chemistry; D013481:Superoxides / Q000737:chemistry; D013843:Thiazines / Q000737:chemistry*; D013844:Thiazoles / Q000737:chemistry*; D014364:Tryptophan / Q000737:chemistry; D014443:Tyrosine / Q000737:chemistry; D014874:Water Pollutants, Chemical / Q000737:chemistry
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D016166:Free Radical Scavengers; D011725:Pyridines; D017382:Reactive Oxygen Species; D012235:Rhodamines; D013843:Thiazines; D013844:Thiazoles; D014874:Water Pollutants, Chemical; C526010:rhodamine B 4-(bis(pyridin-2-ylmethyl)aminomethyl)benzyl ester; D013481:Superoxides; D010894:Piroxicam; D026082:Singlet Oxygen; D014443:Tyrosine; D014364:Tryptophan; D012256:Riboflavin; D000077239:Meloxicam; C032801:tenoxicam
keywords: Oxicams; Photodegradation; Photoprotection; Photosensitization; ROS; Riboflavin