INFLUENCE OF TETRACYCLINES OR CETYLPYRIDINIUM BROMIDE ON ACTIVITY OF FLUOROQUINOLONES IN EUGLENA-GRACILIS

To verify the hypothesis that the fluoroquinolone inhibitors of DNA gy rase generate some oxidant species and subsequently free radicals, the effects of simultaneous action of fluoroquinolones (ofloxacin, flerox acin) and tetracyclines (tetracycline, doxycycline, thiatetracycline) or cetylpyridinium bromide as possible antioxidants on the flagellate Euglena gracilis were examined. Chloroplasts due to their bacterial ch aracter were injured and subsequently eliminated by fluoroquinolone. T he loss of chloroplasts was accompanied by bleaching of originally gre en euglena cells. Tetracyclines, as well as cetylpyridinium bromide, d ecreased the euglena bleaching caused by ofloxacin or fleroxacin. The bleaching induced by ofloxacin or fleroxacin was most effectively inhi bited by thiatetracycline and cetylpyridinium bromide. Control treatin g of cells with tetracyclines or cetylpyridinium bromide alone did not exert any bleaching effect. In vitro weak but significant interaction s between examined substances were established as well.