Probing the Dna Binding Mode of Transition Metal Based Biologically Active Compounds: Validation by Spectroscopic Methods

Few new 4-aminoantipyrine based mixed ligand complexes having imidazole as a potential drug candidate, were designed, synthesized and characterized by analytical and spectral methods. The electronic absorption and electron paramagnetic resonance parameters of Cu(II) complex revealed that the Cu(II) ion exhibits a distorted octahedral geometry with the carbonyl oxygen atom of the 4-aminoantipyrine, azomethine nitrogen atom (condensation between 4-aminoantipyrine and benzaldehyde), nitrogen atom of the imidazole ring and two coordinated chloride anions (occupying the axial position). Similarly the Co(II), Ni(II) and Zn(II) complexes adopted the octahedral geometry, revealed by spectral and analytical data. The interaction of metal complexes with CT-DNA was investigated by UV-Vis absorption, viscosity measurement, cyclic voltammetric method and docking analysis. The results indicated that the Cu(II), Co(II), Ni(II) and Zn(II) complexes interact with DNA through minor groove binding mode with optimum intrinsic binding constants, 4.3×10, 3.1×10, 2.7×10 and 1.6×10 M respectively. The metal complexes exhibited an effective cleavage with pUC19 DNA by an oxidative cleavage mechanism. N.RAMAN Research Department of Chemistry, VHNSN College, Virudhunagar-626 001, India