Patrizio Salice - Photooxidation and Phototoxicity of π-Extended Squaraines

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  Publication Details (including relevant citation   information): Rapozzi, Valentina, Beverina, Luca,   Salice, Patrizio, Pagani, Giorgio A., Camerin, Monica, Xodo,   Luigi E., J. Med. Chem., 2010,   53 (5), pp 2188-2196

  Abstract: This paper describes the synthesis of   π-extended squaraines and their photooxidation properties and   gives an in-depth characterization of these molecules as   photosensitizing agents. Squaraines show a strong absorption in   the tissue transparency window (600?800 nm), and upon   irradiation, they undergo a photooxidation process, leading to   the formation of peroxide and hydroperoxide radicals according to   a type I radical chain process. Confocal laser microscopy   demonstrates that the designed squaraines efficiently internalize   in the cytoplasm and not in the nucleus of the cell. In the dark,   they are scarcely cytotoxic, but after irradition, they promote a   strong dose-dependent phototoxic effect in four different cancer   cells. In HeLa and MCF-7 cells, squaraines 4 and 5, thanks to   their hydrocarbon tails, associate to the membranes and induce   lipid peroxidation, as indicated by a marked increase of   malonyldialdehyde after photodynamic treatment, in agreement with   in vitro photooxidation studies. FACS, caspase-3/7 assays and   time-lapse microscopy demonstrate that the designed squaraines   cause cell death primarily by necrosis.

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