Synthesis, characterization, structural-activity relationship and biomolecular interaction studies of heteroleptic Pd(II) complexes with acetyl pyridine scaffold

Abstract

A series of substituted hydrazinyl pyridine based Schiff base ligands (L1–L6) and corresponding palladium(II) complexes were synthesized and characterized by conductivity measurement, 1H NMR, 13C NMR and liquid chromatography mass spectrometry (LC-MS). Synthesized compounds were screened against various biological activities. UV–Vis spectroscopy, fluorescence spectroscopy, viscosity measurement, and molecular docking studies were used to determine the binding mode between complexes and HS-DNA, which suggest intercalation mode of DNA binding. The protein binding study of complexes was evaluated by UV–visible spectroscopy. Antibacterial activity of the complexes was screened against two Gram (+ve) and three Gram (−ve) bacteria and the result shows that all complexes are more effective against microorganisms than their respective ligands. The cytotoxicity of the synthesized compounds was tested against brine shrimp and S. pombe cell. The LC50 values of the ligand and complexes are found in the range of 9.24–14.12 μg/mL and 5.68–7.94 μg/mL, respectively. The DNA cleavage activity of metal complexes was performed using agarose gel electrophoresis. All compounds were tested for anticancer activity against human colorectal (HCT-116) cancer cell lines. The result shows that all the compounds exhibited effective cytotoxicity against the tested cell line.