Synthesis, characterisation and biological evaluation of tyramine derived schiff base ligand and its transition metal(II) complexes

In this study, a new tyramine derived Schiff base ligand (L) (L=1,3-phenylenebis-4-aminoantipyrinyl-4-aminoethylphenol) and its derived transition metal(II) complexes [Cu(L)Cl2](1), [Ni(L)Cl2](2), [Co(L)Cl₂] (3) and [Zn(L)Cl₂] (4) have been synthesized and well characterized by the way of different spectroscopic and analytical techniques. Analytical and spectroscopic studies result suggests that metal(II) complexes more probably have octahedral geometry. DNA binding tendency of L and metal(II) complexes 1-4 have been assessed by probing their ability to bind with Calf Thymus DNA (CT-DNA) via electronic absorption and cyclic voltammetry titration methods. The results clearly reveal that the metal(II) complexes may interact with DNA through intercalation mode of binding and their binding constant value K_b was found to be in the range of 11.2 - 23.7 ×10⁵ M⁻¹. The DNA damage study has also been investigated by gel electrophoresis technique. Interestingly, it was found that all the complexes could cleave the circular plasmid pBR 322 super coiled (SC) DNA efficiently in the presence of activators. The complexes showed enhanced antifungal (MIC, 2.7 - 6.9 µg/mL) and antibacterial (MIC, 3.1 - 3.9 µg/ mL) activities compared to the free ligand.