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In vitro study of the photocytotoxicity of bathochromically-shifted hypericin derivatives

2009; Springer Science+Business Media; Volume: 8; Issue: 6 Linguagem: Inglês

10.1039/b820817d

1474-9092

M. Roelants, Bernd Lackner, Mario Waser, Heinz Falk, Patrizia Agostinis, Hendrik Van Poppel, Peter de Witte,

Photochromic and Fluorescence Chemistry

Hypericin has excellent photosensitizing properties and displays favorable tumouritropic characteristics, but at the same time exhibits minimal dark toxicity. As such, the compound is a promising photosensitizer in the context of clinical photodynamic therapy (PDT). The present study was undertaken to investigate whether a newly-synthesized series of hypericin derivatives with a bathochromic shift shows promise for future PDT applications. Potentially these structures offer an advantage over the parent compound by being photo-activated by red light, which penetrates deeper into tumour tissue. Our results show that 3 compounds (a dibenzoxazole, a pyridazinone, and especially a dibenzthiazole derivative of hypericin), designed to exhibit a bathochromic shift in their absorption spectrum, demonstrated an efficient singlet oxygen yield and intracellular uptake, and concomitantly a potent photocytotoxic effect under white-light conditions. These results indicate that it is possible to synthesize bathochromically-shifted compounds based on hypericin chemistry which maintain their PDT potential. However, the data also show that the present derivatives are only poor photosensitizers when used under red-light conditions.