Ruthenium complexes have been investigated for various biological applications by virtue of their radical scavenging, DNA binding, receptor binding, and cytotoxic abilities; especially the possible po Show more
Ruthenium complexes have been investigated for various biological applications by virtue of their radical scavenging, DNA binding, receptor binding, and cytotoxic abilities; especially the possible potential application of these complexes in photodynamic therapy (PDT). This study focuses on the synthesis, structural characterization and biological application (pertaining to its cytotoxicity and radical generation) of ruthenium complexed with salicylaldehyde fumaryl-dihydrazone (slfhH4 ), salicylaldehyde glutaryl-di-hydrazone (slfgH4 ) and 2,2'-bipyridine (bpy). During the synthesis, the anticipated complex was precipitated out but as serendipity, Ruthenium(II) tris (2,2'-bipyridyl) monochloride nonahydrate {[Ru(bpy)3 ]2+ .Cl.9H2 O} (RBMN) and Ruthenium(II) tris (2,2'-bipyridyl) monochloride septahydrate {[Ru(bpy)3 ]2+ .Cl.7H2 O}(RBMS) were crystallized from the filtrate. The crystal structure of complexes RBMN and RBMS were determined by a single-crystal X-ray diffraction methods and it showed that chlorine anion lies at the crystallographic axis and forms a halogen hydrogen-bonded organic framework (XHOF) to provide the stability. In comparison with similar structures in Cambridge Crystallographic Data Center (CCDC) revealed that the nature of the XHOF framework and the layered packing are conserved. The compounds showed excellent cytotoxic ability (against L6 cells) and the nitro blue tetrazolium (NBT) assay upon irradiation to light revealed its ability to produce reactive oxygen species (ROS). The presence of partially occupied water molecules in the layered organization within the crystal packing mimics the release of ROS resulting in cytotoxicity. The structural results together with the biological data make these complexes interesting candidates for potential photosensitizers for PDT applications. Show less
The photophysical and biological properties of two new phenanthroline-based ligand ruthenium complexes were investigated in detail. Their DNA interaction modes were determined to be the intercalation Show more
The photophysical and biological properties of two new phenanthroline-based ligand ruthenium complexes were investigated in detail. Their DNA interaction modes were determined to be the intercalation mode using spectra titration and viscosity measurements. Under irradiation, obvious photo-reduced DNA cleavages were observed in the two complexes via singlet oxygen generation. Furthermore, complex 2 showed higher DNA affinity, photocleavage activity, and singlet oxygen quantum yields than complex 1. The two complexes showed no toxicity towards tumor cells (HeLa, A549, and A375) in the dark. However, obvious photocytotoxicities were observed in the two complexes. Complex 2 exhibited large PIs (phototherapeutic indices) (ca. 400) towards HeLa cells. The study suggests that these complexes may act as DNA intercalators, DNA photocleavers, and photocytotoxic agents. Show less