DNA binding by Ru(II)–bis(bipyridine)–pteridinyl complexes

Abstract

The interactions of five bis(bipyridyl) Ru(II) complexes of pteridinyl-phenanthroline ligands with calf thymus DNA have been studied. The pteridinyl extensions were selected to provide hydrogen-bonding patterns complementary to the purine and pyrimidine bases of DNA and RNA. The study includes three new complexes [Ru(bpy)(2)(L-pterin)](2+), [Ru(bpy)(2)(L-amino)](2+), and [Ru(bpy)(2)(L-diamino)](2+) (bpy is 2,2'-bipyridine and L-pterin, L-amino, and L-diamino are phenanthroline fused to pterin, 4-aminopteridine, and 2,4-diaminopteridine), two previously reported complexes [Ru(bpy)(2)(L-allox)](2+) and [Ru(bpy)(2)(L-Me(2)allox)](2+) (L-allox and L-Me(2)allox are phenanthroline fused to alloxazine and 1,3-dimethyalloxazine), the well-known DNA intercalator [Ru(bpy)(2)(dppz)](2+) (dppz is dipyridophenazine), and the negative control [Ru(bpy)(3)](2+). Reported are the syntheses of the three new Ru-pteridinyl complexes and the results of calf thymus DNA binding experiments as probed by absorption and fluorescence spectroscopy, viscometry, and thermal denaturation titrations. All Ru-pteridine complexes bind to DNA via an intercalative mode of comparable strength. Two of these four complexes--[Ru(bpy)(2)(L-pterin)](2+) and [Ru(bpy)(2)(L-allox)](2+)--exhibit biphasic DNA melting curves interpreted as reflecting exceptionally stable surface binding. Three new complexes--[Ru(bpy)(2)(L-diamino)](2+), [Ru(bpy)(2)(L-amino)](2) and [Ru(bpy)(2)(L-pterin)](2+)--behave as DNA molecular "light switches."

10,12-Dimethylpteridino[6,7-f][1,10]phenanthroline-11,13(10H,12H)-dione–chloroform (1/1)

“…The molecular planes in alternating stacks are oriented at 12.46 (2)° to each other; this could at least partially be due to packing constraints imposed by the slightly out-of-plane C18-methyl group (see packing diagram in Figure 2). Studies involving the non-methylated analog of the title compound have also been reported (Chen et al, 2010;Dalton et al, 2008;Gao et al, 2007;Ozawa et al, 2006) although, to our knowledge, no crystal structures of this analog have been reported.…”

“…For the possible use of metal complexes of this ligand as DNA probes, see: Gao et al (2007); Lawrence et al (2006). For studies involving the non-methylated analog of the title compound, see: Chen et al (2010); Dalton et al (2008); Ozawa et al (2006). For a related stucture, see: Ton & Bolte (2005).…”

DNA Binding, Antioxidant Activity, and DNA Damage Protection of Chiral Macrocyclic Mn(III) Salen Complexes

“…1 Synthesis of chiral macrocyclic salen ligands S-1 0 , R-1 0 , S-2 0 , and R-2 0 . A solution of chloromethylsalicylaldehyde (B) in dry toluene (20 mmol, 20 ml) was added dropwise to a stirring solution of piperazine in dry toluene (10 mmol, 20 ml), and reaction mixture was stirred at room temperature.…”

Crystal structures, DNA-binding studies and antioxidant activities of the Ln(III) complexes with 7-methoxychromone-3-carbaldehyde-isonicotinoyl hydrazone

“…Since the intracellular target for a wide range of anticancer and antibiotic drugs is DNA, the binding studies of small molecules with DNA are extremely useful in understanding the drug-DNA interactions, designing new and promising drugs for clinical applications and developing sensitive chemical probes of nucleic acid structure (Dalton et al 2008;Sun et al 2008). During the last few decades, identifying small molecules that are capable of binding DNA through intercalation mode has attracted considerable interest (Dhara et al 2006).…”