Biological evaluation of organometallic palladium(II) complexes containing 4‐hydroxybenzoic acid (3‐ethoxy‐2‐hydroxybenzylidene)hydrazide: Synthesis,structure, DNA/protein binding,antioxidant activity and cytotoxicity

New palladium(II) complexes, Pd(PPh₃)L] ( 2 ) and Pd(AsPh₃)L] ( 3 ), were synthesized using 4‐hydroxybenzoic acid (3‐ethoxy‐2‐hydroxybenzylidene)hydrazide ( 1 ) ligand (H₂L), and characterized using various physicochemical techniques. The molecular structures of 2 and 3 were determined using single‐crystal X‐ray diffraction, which reveals a square planar geometry around the palladium(II) metal ion. In vitro DNA binding studies were conducted using UV–visible absorption spectroscopy, emission spectroscopy, cyclic voltammetry and viscosity measurements, which suggest that the metal complexes act as efficient DNA binders. The interaction of ligand H₂L and complexes 2 and 3 with bovine serum albumin (BSA) was investigated using UV–visible and fluorescence spectroscopies. Absorption and emission spectral studies indicate that complexes 2 and 3 interact with BSA protein more strongly than the parent ligand. The free radical scavenging potential of all the synthesised compounds ( 1 – 3 ) was also investigated under in vitro conditions. In addition, the in vitro cytotoxicity of the complexes to tumour cells lines (HeLa and MCF‐7) was examined using the MTT assay method.