DNA oxidation photoinduced by Norharmane Rhenium(I) polypyridyl complexes: effect of the bidentate N,N' ligands on the damage profile

MAISULS, IVAN; CABRERIZO, FRANCO; DAVID GARA, PEDRO; EPE, BERND; RUIZ, GUSTAVO TEODOSIO

CHEMISTRY-A EUROPEAN JOURNAL

WILEY-V C H VERLAG GMBH

Año: 2018 vol. 24 p. 12902 - 12911

0947-6539

Re(I)-polypyridyl complexes show quite interesting and distinctive photochemical and photosensitizing properties. This work describes the capability to induce (or photoinduce) DNA damage of three Re(I)-complexes with a naturally occurring alkaloid called norharmane (nHo) as ligand: [Re(CO)3(nHo)(L)]CF3SO3 where L = 2,2´-bipyridine (ReBpy), phenanthroline (RePhen) or dipyrido[3,2- a:2′,3′-c]phenazine (ReDppz). The interaction of the complexes with DNA was investigated by steady-state and time-resolvedspectroscopy. Data show that the mode and strength of interaction depend on the chemical structure of the bidentate ligand. The complexes show a major static contribution to the overall interaction, giving rise to the formation of non-covalent adducts with DNA, and the particular trend observed was RePhen > ReDppz > ReBpy. Photo-oxidation at the purine bases represents the major DNA damaging mechanism. RePhen also induces single-strand breaks in a yield similar to that of base damage, suggesting an- additional photosensitizing pathway. Also, we performed the Ames test to evaluate the cytotoxic and mutagenic properties of both nonirradiated and photoexcited complexes. RePhen, but not the other complexes, turned out to be both toxic and phototoxic for the bacteria.