PHOTODEGRADATION PRODUCTS OF A NEW ANTIBACTERIAL FLUOROQUINOLONE DERIVATIVE, ORBIFLOXACIN, IN AQUEOUS-SOLUTION

A new antibacterial fluoroquinolone derivative, orbifloxacin (ORFX), i s decomposed photochemically in aqueous solution, When ORFX solution w as irradiated with a chemical lamp or sunlight, three major photodegra dation products were isolated by preparative HPLC. These degradation p roducts were identified by electron-impact mass spectrometry, liquid-s econdary-ion mass spectrometry and H-1-NMR spectroscopy. Moreover, the photodegradation pathway was investigated by a similar study using se veral fluoroquinolone derivatives which were presumed to be the interm ediates of the photoreaction of ORFX, Consequently, it was found that two main photochemical reactions, the decomposition of the dimethylpip erazinyl moiety and the elimination of the cyclopropyl group, take pla ce in ORFX, The detected structures of photodegradation products and t he photodegradation studies of the postulated intermediates suggested that the photodecomposition of the dimethylpiperazinyl ring at the 7-p osition and the elimination of the cyclopropyl group at the 1-position occurred concurrently with the release of fluorine at the 8-position.