Sonodynamic Effects of Lomefloxacin Derivatives Conjugated with Methoxy Polyethylene Glycol on Sarcoma 180 Cells

Background: Sonodynamic therapy (SDT) is a promising methodology for cancer treatment. Lomefloxacin hydrochloride (LFLX) has been reported to have sonodymamic antitumor effects. Materials and Methods: We synthesized LFLX derivatives conjugated with methoxy polyethylene glycol (PEGylated LFLXs) and investigated their ultrasonically induced antitumor effects. Results: After ultrasound exposure at 2.0 MHz for 30 s, the survival rates of Sarcoma 180 cells in the presence of lower molecular weight PEGylated LFLXs (200 μM) were significantly lower than those of the control and the LFLX at 1.5 and 2.0 W/cm 2 . This enhancement was significantly inhibited by the addition of L-histidine, but not by D-mannitol or superoxide dismutase. There was no apparent cell damage in the presence of high molecular weight PEGylated LFLX even at 3.0 W/cm 2 . Conclusion: These findings indicate that the sonodynamic antitumor effects of lower molecular weight PEGylated LFLXs are better than those of LFLX.