RESUMO
Three mononuclear Cu(II) complexes [Cu(naph-phe)phen] (1), [Cu(naph-tyr)(phen)] (2) and [Cu(naph-trp)(phen)] (3) were synthesized, characterized and their biological properties were studied. Complexes 1, 2, 3 exhibit square pyramidal geometry where Schiff base acts as a binegative tridentate ONO donor ligand and phen acts as NN donor ligand. CT-DNA binding studies revealed that the complexes bind through intercalative mode and show good binding propensity. The hydrolytic DNA cleavage activity of these complexes has been studied using gel electrophoresis. The DNA binding and cleavage affinities decrease in the order of 3>2>1. The in-vitro antimicrobial activities of the complexes were also studied.
Assuntos
Complexos de Coordenação/síntese química , Cobre/química , Substâncias Intercalantes/síntese química , Fenantrolinas/química , Bases de Schiff/química , Ligação Competitiva/efeitos dos fármacos , Complexos de Coordenação/química , Complexos de Coordenação/farmacologia , DNA/química , DNA/metabolismo , Clivagem do DNA/efeitos dos fármacos , Espectroscopia de Ressonância de Spin Eletrônica , Eletroforese em Gel de Ágar , Bactérias Gram-Negativas/efeitos dos fármacos , Bactérias Gram-Positivas/efeitos dos fármacos , Substâncias Intercalantes/química , Substâncias Intercalantes/farmacologia , Espectrofotometria Ultravioleta , Termogravimetria , ViscosidadeRESUMO
Three mononuclear Cu(II) complexes, [CuCl(naph-pa)] (1), [Cu(bipy)(naph-pa)]Cl (2), and [Cu(naph-pa)(phen)]Cl (3) ((naph-pa)=Schiff base derived from the condensation of 2-hydroxynaphthalene-1-carbaldehyde and 2-picolylamine (=2-(aminomethyl)pyridine), bipy=2,2'-bypiridine, and phen=1,10-phenanthroline) were synthesized and characterized. Complex 1 exhibits square-planar geometry, and 2 and 3 exhibit square pyramidal geometry, where Schiff base and bipy/phen act as NNO and as NN donor ligands, respectively. CT (Calf thymus)-DNA-binding studies revealed that the complexes bind through intercalative mode and show good binding propensity (intrinsic binding constant K(b): 0.98×10(5), 2.22×10(5), and 2.67×10(5) M(-1) for 1-3, resp.). The oxidative and hydrolytic DNA-cleavage activity of these complexes has been studied by gel electrophoresis: all the complexes displayed chemical nuclease activity in the presence and absence of H(2)O(2). From the kinetic experiments, hydrolytic DNA cleavage rate constants were determined as 2.48, 3.32, and 4.10 h(-1) for 1-3, respectively. It amounts to (0.68-1.14)×10(8)-fold rate enhancement compared to non-catalyzed DNA cleavage, which is impressive. The complexes display binding and cleavage propensity to DNA in the order of 3>2>1.
Assuntos
Complexos de Coordenação/química , Cobre/química , DNA/metabolismo , Piridinas/química , Bases de Schiff/química , Animais , Bovinos , Complexos de Coordenação/síntese química , Clivagem do DNA , Hidrólise , Conformação MolecularRESUMO
Ternary Cu(II) complexes [Cu(II)(saltrp)(B)] (1,2), (saltrp=salicylidene tryptophan, B=1,10 phenathroline (1) or 2,2' bipyridine (2)) were synthesized and characterized. Complex 2 was structurally characterized by single crystal X-ray crystallography. The molecular structure shows a distorted square pyramidal coordination geometry (CuN(3)O(2)) in which the ONO donor Schiff base is bonded to the Cu(II) in the basal plane. The N,N donor heterocyclic base displays an axial-equatorial binding mode. CT-DNA binding studies revealed that the complexes show good binding propensity (Intrinsic binding constant, K(b)=3.32×10(5) M(-1) for 1 and K(b)=3.10×10(5) M(-1) for 2). The catalytic role of these complexes in the oxidative and hydrolytic cleavage of DNA was studied in detail. Complex 1 binds and cleaves DNA more efficiently as compared to 2. From the kinetic experiments, rate constants for the hydrolysis of phosphodiester bond of DNA backbone were determined as 1.94 h(-1) and 1.05 h(-1) for 1 and 2 respectively. It amounts to (2.93-5.41)×10(7) fold rate enhancement compared to uncatalyzed double stranded DNA, which is impressive as compared to related Cu(II) Schiff base complexes.