Exploring the DNA Interaction and Antimicrobial Screening of Mixed Ligand Transition Metal(II) Complexes containing Isoniazid-Lawsone Schiff Base: Synthesis, Structural Elucidation and Molecular Docking

Designing of novel metal-based molecular drugs is an effective approach to fight against the ongoing threat of antimicrobial, anticancer and antioxidant resistance. With this objective, in current work, novel mixed ligand Cu(II), Co(II), Ni(II) and Zn(II) complexes have been designed and prepared by coordinating isoniazid Schiff base as main ligand and lawsone as co-ligand. Moreover, the synthesis of these complexes have been explored with the purpose of creating stable and planar co-ligand (lawsone), thereby investigating their DNA interaction ability and other biological applications. The geometrical characteristics of these synthesized complexes were examined by elemental analysis, UV-Vis, FT-IR, NMR, Mass and EPR spectral analyses and conductivity measurements. The observed spectral data support an octahedral geometry of the complexes. The low molar conductance value specifies the non-electrolytic nature of the synthesized complexes. Their magnetic susceptibility and EPR spectral data confirm the monomeric nature of all the metal(II) complexes. The interaction between the complexes and ct-DNA is evaluated using electronic absorption titration and viscosity measurements, cyclic voltammetry and molecular modelling studies. DNA study reveals that the complexes have intercalation type of binding. The MIC values of the synthesized complexes expose their better antimicrobial inhibiting features than the ligand. DFT studies were also carried out using Gaussian 09 software 6-31G/B3LYP set. Moreover, the molecular docking interaction was done in order to support the in vitro DNA interaction experiments. The conclusions of all the studies reveal that Cu(II) complex exhibits good biological characteristics than the free ligand and other metal(II) complexes.