Toward hypericin-derived potential photodynamic therapy agents.
To optimize a hypericin derivative as a potential photodynamic therapy agent its light-induced singlet oxygen/superoxide radical formation capability should be enhanced and its long-wavelength absorption band should be bathochromically shifted to better match medicinal lasers. A heavy-atom-substituted derivative was realized by electrophilic iodination of hypericin to yield 2,5-diiodo-hypericin. Using photodestruction of bilirubin IX alpha this derivative was demonstrated to exhibit an enhanced light-induced singlet oxygen/superoxide radical formation capability as compared to hypericin. With respect to a bathochromically shifted derivative styryl residues were attached to the methyl groups of hypericin by de novo ring synthesis. Although the long-wavelength absorption band of this derivative displayed a bathochromic shift of nearly 40 nm it unfortunately immediately underwent an intramolecular [2 + 2] cycloaddition to yield the corresponding cyclobutane derivative in which the added conjugation system became interrupted.
Obermüller
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Institute of Chemistry, Johannes Kepler University, Altenbergerstrasse 69, A 4040 Linz, Austria.
Hohenthanner
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Falk
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D000873:Anthracenes; D066298:In Vitro Techniques; D009682:Magnetic Resonance Spectroscopy; D010100:Oxygen / Q000737:chemistry; D010569:Perylene / Q000031:analogs & derivatives* / Q000138:chemical synthesis / Q000737:chemistry*; D010777:Photochemistry; D010778:Photochemotherapy; D017319:Photosensitizing Agents / Q000138:chemical synthesis / Q000737:chemistry*; D026082:Singlet Oxygen; D013481:Superoxides / Q000737:chemistry
D000873:Anthracenes; D017319:Photosensitizing Agents; D013481:Superoxides; D026082:Singlet Oxygen; D010569:Perylene; C004965:hypericin; D010100:Oxygen