Iron(III) salicylates of dipicolylamine bases showing photo-induced anticancer activity and cytosolic localization

Abstract

An iron(III) salicylate having a dipicolylamine base (andpa) with a photoactive anthracenyl moiety is prepared, characterized, and studied for its photo-induced anticancer activity and cellular localization in HeLa and MCF-7 cells. Its phenyl analogue is structurally characterized by X-ray crystallography. The complex has a ternary structure in which the dipicolylamine ligand and salicylic acid in dianionic form (sal) display respective tridentate and bidentate mode of coordination in [Fe(sal)(phdpa)Cl] (1). Complex [Fe(sal)(andpa)Cl] (2) having a pendant anthracenyl moiety shows significant photocytotoxicity in visible light (400–700 nm) giving IC50 values of 8.6 ± 0.7 and 3.4 ± 0.9 μM in HeLa and MCF-7 cells, while being essentially nontoxic in the dark (IC50 > 100 μM). The complex shows cytosolic localization in the cancer cells. Formation of hydroxyl radicals (radical dotOH) as the reactive oxygen species is evidenced from the pUC19 DNA photocleavage studies.