Zinc octa-n-alkyl phthalocyanines in photodynamic therapy: photophysical properties, accumulation and apoptosis in cell cultures, studies in erythrocytes and topical application to Balb/c mice skin

Lars Kaestner, Maro Cesson, Kawser Kassab, Terje Christensen, Paul D. Edminson, Michael J. Cook, Isabelle Chambrier, Giulio Jori

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Two octa-substituted phthalocyanines, namely 1,4,8,11,15,18,22,25-octakis(decyl) phthalocyaninato zinc(II) (ZnODPc) and 1,4,8,11,15,18,22,25-octakis(pentyl) phthalocyaninato zinc(II) (ZnOPPc), were investigated for their use in photodynamic therapy ( PDT) after topical application. Both substances exhibited favourable properties as photosensitisers in vitro: absorption maxima around 700 nm with absorption coefficients of about 190000 (M-1 cm(-1)), a singlet oxygen quantum yield of 0.47 +/- 0.02 (ZnODPc), and good accumulation in keratinocytes and. broblasts. Cell death after phthalocyanine-photosensitisation appeared to occur mainly via apoptosis. The in vivo experiments demonstrated a good accumulation of the phthalocyanines after topical application in a tetrahydrofuran - azone formulation onto the dorsal skin of Balb/c mice: [(4.6 - 4.7) +/- 1.0]% of deposited dye could be recovered after 3 h from deposition. ZnODPc showed significantly better skin-photosensitising properties than ZnOPPc and is therefore a potential candidate for the treatment of psoriasis.
Original languageEnglish
Pages (from-to)660-667
Number of pages8
JournalPhotochemical & Photobiological Sciences
Issue number6
Publication statusPublished - 2003

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