Chemical and Biological Study of Some Transition Metal Complexes with Guanine as Ligand

DNA sequences rich in Guanine can come together to form G-quadruplexes, which are tetra-stranded structures. According to some theories, these secondary DNA structures may have a role in the control of several important biological processes. The telomere and the promoter regions of several oncogenes contain guanine-rich sequences that have the potential to create G-quadruplexes in the human genome. The aim of the work was to Prepare guanine complexes with metal ions (Cd(II), Fe(II), Cu(II), Zn(II), Cr(III), Fe(III), Pb(II), and Mn(II)). The complexes were characterised by physical chemical and spectroscopic techniques such as electrical conductivity, metal content, infrared, UV-visible and molar conductivity techniques. The molar ratio of Guanine to metal ion reaction is 1:2, which is determined by the molar ratio method. Dissociation constants for guanine ligands were determined spectrophotometrically. The effect of solvents on the electronic spectra of guanine ligands was studied using solvents of different polarities. The biological activity of guanine ligands and their metal complexes was tested in vitro against selected fungal and bacterial species. The results showed satisfactory spectra for the tested organisms.