Effects of bio-compatible metal ions on rufloxacin photochemistry, photophysics and photosensitization: Copper(II)

The presence of copper(II) in the micromolar range modulates the photodegradation rate of the fluoroquinolone Rufloxacin (RFX), both under air and in nitrogen saturated aqueous solution. The photodegradation rate of RFX under aerobic conditions decreases in the presence of metal ions, and no change in the nature of the photoproducts is observed. In anaerobic media, RFX photodegradation rate increases with increasing copper(II) concentration and the photoproducts distribution changes.Copper(II) inhibits formation of type II products of 2′-deoxyguanosine diagnostic of photosensitization mediated by singlet oxygen. The overall results provide a clear example demonstrating how a bio-compatible trace element influences efficiently not only the bioavailability of a drug but also its molecular mechanism of photodegradation and photosensitization.