Synthesis, Characterization and in vitro Anticancer Studies of New Co(II), Ni(II), Cu(II) and Zn(II) Complexes of (E)-4-((Quinoline-8-ylimino)methyl)benzene-1,2,3-triol Ligand

Herein, a new tridentate (NNO) Schiff base ligand, (E)-4-[(quinoline-8-ylimino)methyl]benzene-1,2,3- triol derived from the condensation of 8-aminoquinoline with 2,3,4-trihydroxy benzaldehyde is reported. The ligand was complexed with certain metal ions like Co(II) (1), Ni(II) (2), Cu(II) (3), Zn(II) (4) and were characterized by various spectroscopic and analytical techniques such as FT-IR, UV-Vis, 1H NMR, 13C NMR, ESI-Mass, ESR, elemental analysis and magnetic susceptibility. Spectral data revealed octahedral geometry for cobalt(II), nickel(II), copper(II) complexes and tetrahedral geometry for zinc(II) complex. All the metal(II) complexes along with the Schiff base ligand were screened for their anticancer activities. The CT-DNA binding studies revealed high binding propensity for metal complexes with Kb values 1.50 × 104 M-1 for 1; 3.62 × 104 M-1 for 2; 2.53 × 104 M-1 for 3 and 1.8 × 104 M-1 for 4, respectively. Anticancer studies against A549 & MCF-7 demonstrated excellent antiproliferative activity with IC50 values in the range 17.62-48.82 μM. A standard drug cisplatin was employed to compare the activity of metal complexes. The complexes exhibited remarkable antitumour activity due to their high binding ability with DNA. It is interesting to observe that the complexes did not produce any cytotoxicity towards the normal cell lines.