First ruthenium(II) polypyridyl complex as a true molecular "light switch" for triplex RNA structure: [Ru(phen)2(mdpz)]2+ enhances the stability of Poly(U)·Poly(A)*Poly(U).

Stabilization of triple helical structures is extremely important for carrying out their biological functions. Nucleic acid triple helices may be formed with DNA or RNA strands. In contrast to many studies in DNA, little has been reported concerning the recognition of the RNA triplex by transition-metal complexes. In this article, [Ru(phen)(2)(mdpz)](2+) (Ru1) is the first metal complex able to enhance the stability of the RNA triplex Poly(U)·Poly(A)*Poly(U) and serve as a prominent molecular "light switch" for the RNA triplex.

Synthesis, characterization, nucleic acid binding, and cytotoxic activity of a Ru(II) polypyridyl complex.

The binding properties of [Ru(bpy)(2)(H(2)IIP)](2+) (1) {bpy=2,2'-bipyridine, H(2)IIP=2-(indole-3-yl)-imidazolo[4,5-f][1,10]phenanthroline} with calf thymus DNA (CT-DNA) and yeast tRNA have been investigated comparatively by different spectroscopic and viscosity measurements. The results suggest that the affinity of complex 1 binding with yeast tRNA is stronger than that of complex 1 binding with CT-DNA, and complex 1 is a better enantioselective binder to yeast tRNA than to CT-DNA. The toxicity of complex 1 was concentration dependent, and HL-60 cells are more sensitive to complex 1 than Hep-G2 cells; complex 1 could induce Hep-G2 cell apoptosis.