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.

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.