Porphyrins and metalloporphyrins have been extensively investigated as potential anticancer drugs working as DNA binding agents as well as photosensitizer in the photodynamic therapy (PDT). Conjugation of the macrocycle with organo-metallic complexes have been considered a powerful tool to implement the soly. of the porphyrin and to provide addnl. cytotoxic properties. Here, we prepd. six four-fold sym. cationic porphyrin-ruthenium(II) conjugates which differ one from each other's for the nature of the linker, the substituents on the Ru(II) fragments and the total pos. charge and we investigated their interaction with DNA templates different from the B form. Our data suggested that the tested conjugated are not selective toward the G-quadruplex form of the human telomeric sequence. Indeed, unfolded DNA efficiently works as matrix for the cationic conjugates. Nevertheless, they are extremely efficient in cleaving the macromol. upon irradn., irresp. of its structural arrangement.
