Synthesis, characterization, and crystal structure of a functionalized ruthenium(II) polypyridyl complex with fused triazinone as ligand

Targeting human telomeric G-quadruplex DNA and inhibition of telomerase activity with [(dmb)2Ru(obip)Ru(dmb)2](4+)

Inhibition of telomerase by inducing/stabilizing G-quadruplex formation is a promising strategy to design new anticancer drugs. We synthesized and characterized a new dinuclear complex [(dmb)₂Ru(obip)Ru(dmb)₂]⁴⁺ (dmb = 4,4’-dimethyl-2,2’-bipyridine, obip = (2-(2-pyridyl)imidazo[4,5-f][1,10]phenanthroline) with high affinity for both antiparallel and mixed parallel / antiparallel G-quadruplex DNA. This complex can promote the formation and stabilize G-quadruplex DNA. Dialysis and TRAP experiments indicated that [(dmb)₂Ru(obip)Ru(dmb)₂]⁴⁺ acted as an excellent telomerase inhibitor due to its obvious selectivity for G-quadruplex DNA rather than double stranded DNA. In vitro co-culture experiments implied that [(dmb)₂Ru(obip)Ru(dmb)₂]⁴⁺ inhibited telomerase activity and hindered cancer cell proliferation without side effects to normal fibroblast cells. TUNEL assay indicated that inhibition of telomerase activity induced DNA cleavage further apoptosis in cancer cells. Therefore, Ru^II complex represents an exciting opportunity for anticancer drug design by specifically targeting cancer cell G-quadruplexes DNA.

Synthesis, antitumor activity and structure–activity relationships of a series of Ru(II) complexes

A series of octahedral Ru(II) polypyridyl complexes, [Ru(phen)(2)L](2+) (L=R-PIP and PIP=2-phenylimidazo[4,5-f][1,10]phenanthroline) were synthesized and characterized by elementary analysis, (1)H NMR and ES-MS, as well as UV-visible spectra and emission spectra. The antitumor activities of these complexes and their corresponding ligands were investigated against mouse leukemia L1210 cells, human oral epidermoid carcinoma KB cells, human promyelocytic leukemia cells (HL-60) and Bel-7402 liver cancer cells by MTT (3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide) assay. It was found that the complexes [Ru(phen)(2)L](2+) (L=R-PIP) exert rather potent activities against all of these cell lines, especially for the KB cells (IC(50)=4.7+/-1.3 microM). The binding affinities of these Ru(II) complexes to CT-DNA (calf thymus DNA), as well as the DNA-unwinding properties on supercoiled pBR322 DNA were also investigated. The results showed that these Ru(II) polypyridyl complexes not only had an excellent DNA-binding property but also possessed a highly effective DNA-photocleavage ability. The structure-activity relationships and antitumor mechanism were also carefully discussed.