Photochemical properties of porphryin C: an agent for use in tumor phototherapy

Kenneth P. Ghiggino, Louise E. Bennett, Robert W. Henderson

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9 Citations (Scopus)


Abstract— The absorption and fluorescence properties of porphyrin c (Pc), the porphyrin chromophore present in cytochrome c, have been determined in several solvents and micellar environments. In aqueous buffer solutions at pH 7.5 Pc may exist in both a fluorescent monomeric form with quantum yield of fluorescence, (Φf,) ∼ 0.03, and fluorescence lifetime, (τf) ∼ 8 ns, and as a non‐fluorescent aggregate. The proportion of monomeric form is higher in organic solvents and micelles but is reduced with increasing porphyrin concentrations in aqueous solutions. Porphyrin c readily complexes with Zn2+ to produce a fluorescent chelate (Zn‐Pc) with Φf, ∼ 0.02 and τf, ∼ 2 ns at pH 7.5. The yields of singlet excited oxygen formation from Pc and the Zn‐Pc complex are higher than observed for hematoporphyrin derivative (HpD). Both Pc and Zn‐Pc are effective agents in tumor phototherapy and do not induce the prolonged cutaneous photosensitivity observed with the use of HpD.

Original languageEnglish
Pages (from-to)65-72
Number of pages8
JournalPhotochemistry and Photobiology
Issue number1
Publication statusPublished - 1 Jan 1988
Externally publishedYes

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