RHODAMINE DYES AS POTENTIAL AGENTS FOR PHOTOCHEMOTHERAPY OF CANCER IN HUMAN BLADDER-CARCINOMA CELLS

  • 15 July 1989
    • journal article
    • research article
    • Vol. 49  (14) , 3961-3965
Abstract
The phototoxicity in vitro of rhodamine 123 and tetrabromorhodamine 123 (TBR) was compared, in order to asses their photochemotherapeutic potential. Exposure to 514.5-nm radiation from an argon ion laser caused phototoxicity in MGH-U1 bladder carcinoma cells previously treated with either dye at 10 .mu.M for 30 min. As assessed by colony formation and cellular morphology, TBR was markedly more phtotoxic than rhodamine 123, reflecting increased intersystem crossing of TBR to the triplet manifold via spin-orbital coupling induced by the heavy bromine atoms. Photoreactions oF TBR very efficiently generated singlet oxygen (1O2) in solution; furthermore, irradiation of TBR-treated cells was significantly more toxic when performed in the presence of deuterium oxide, an enhancer of damage caused by 1O2. Retention of fluorescence in TBR-treated cells was enhanced by irradiation, indicating that a stable photoproduct may be formed in reaction with cellular components.