THE EFFECT OF STATIC MAGNETIC-FIELDS ON THE PHOTOHEMOLYSIS OF HUMAN ERYTHROCYTES BY KETOPROFEN

Ultraviolet irradiation (lambda > 300 nm) of the nonsteroidal anti-inf lammatory agent ketoprofen (KP, 3-benzoyl-alpha-methylbenzoacetic acid ) in aqueous solution, pH 7.4, results in heterolytic decarboxylation of the drug to give 3-ethylbenzophenone (EtBP). Ketoprofen caused the photohemolysis of human erythrocytes probably as a result of lipid per oxidation. Application of a static magnetic field (250-1500 G) during UV (>300 nm) irradiation of KP and erythrocytes significantly decrease d the time required for photohemolysis. This observation suggests that KP-induced photohemolysis involves the initial generation of a triple t radical pair derived from the reaction of triplet state KP (or 3-EtB P) with erythrocyte component(s) probably lipids. The magnetic field i ncreases the concentration and/or lifetime of free radicals that escap e from the radical pair so that the critical radical concentration nee ded to initiate membrane damage and cause cell lysis is reached sooner . Spin-trapping studies with 2,6-dibromo-1-nitrosobenzene-4-sulfonate confirmed that the application of an external static magnetic field in creased the concentration of radicals released during the photolysis o f either KP or 3-EtBP dissolved in organized media such as sodium dode cylsulfate micelles.