Effect of Acetazolamide on Hypericin Photocytotoxicity

Abstract The photodynamic action of hypericin (HYP) IN VITRO was evaluated using human leukemic HL-60 and lung carcinoma A549 cell lines. After illumination HYP (1 × 10 -5 M) reduced the proliferation and/or survival of HL-60 and A549 cells vs. controls to almost to 0 % and 29 %, respectively. A lower concentration of HYP (1 × 10 -6 M) decreased the proliferation and/or survival only in HL-60 cells. Non-cytotoxic concentrations of the carbonic anhydrase inhibitor acetazolamide (ACTZ) (1 × 10 -3 -1 × 10 -6 M) significantly potentiated these effects of HYP (1 × 10 -6 M) in HL-60, but not in the A549 cell line. The highest concentration of ACTZ (1 × 10 -3 M) also induced an increase of the subdiploid G 0 /G 1 population in HYP (1 × 10 -6 M) treated HL-60 cells from 14 % to 24 %. The results indicate that the photogenerated pH drop may participate in the potentiation of the photodynamic action of HYP observed in leukemia cells.