Bacteriopheophorbide esters: photosensitizers without "threshold dose"?

Joerg G. Moser; Andreas Ostrowsky; Maria Guemuesdagli; Beate Kleiber

doi:10.1117/12.168653

1 March 1994 Bacteriopheophorbide esters: photosensitizers without "threshold dose"?

Joerg G. Moser, Andreas Ostrowsky, Maria Guemuesdagli, Beate Kleiber

Proceedings Volume 2078, Photodynamic Therapy of Cancer; (1994) https://doi.org/10.1117/12.168653
Event: Europto Biomedical Optics '93, 1993, Budapest, Hungary

Abstract

Uptake and phototoxicity of the methyl-, ethyl-, n-propyl, and 2-propyl esters of 13²- hydroxy bacteriopheophorbide a were studied in OAT 75 SCLC cells and 3 different amelanotic melanoma cell lines. (A 375, Melur SP 18, SkAMel 25). Specific phototoxicity did not substantially differ for the different esters. Most surprisingly, these photosensitizers did not show any significant threshold behavior: even at 25 (mu) W/cm² (775 nm, diode laser) cancer cell suspensions were killed in a time-dependent logarithmic fashion. Furthermore, phototoxicity is enhanced at low power densities if compared with the effects at 1 - 10 mW/cm². This can be related only in part to a lack of oxygen at higher power densities. Complementary experiments confirmed that threshold is power but not dose dependent. Thus, threshold power density should be included into a prospective list of criteria characterizing photosensitizers suitable for photodynamic cancer therapy. The obvious lack of a limiting power density in bacteriopheophobide a esters make these sensitizers a prospective tool for tumor therapy in considerable tissue depth.

Citation Download Citation

Joerg G. Moser, Andreas Ostrowsky, Maria Guemuesdagli, and Beate Kleiber "Bacteriopheophorbide esters: photosensitizers without "threshold dose"?", Proc. SPIE 2078, Photodynamic Therapy of Cancer, (1 March 1994); https://doi.org/10.1117/12.168653

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