Novel fluorescence palladium-alkoxime complexes: Synthesis, characterization, DNA/BSA spectroscopic and docking studies, evaluation of cytotoxicity and DNA cleavage mechanism

Abstract

The new alkoxime ligand (E)-anthracene-9-carbaldehyde-O-methyl oxime (1) derivative of 9-anthraldehyde and its palladium (II) complexes trans-Pd(C15H10NOCH3)2(OAc)2 (2) and [cis-Pd(C15H10NOCH3)(Py)2(OAc)](OAc) (3) were synthesized and characterized by spectroscopic techniques. Also, the ligand (1) structure was characterized by X-ray crystallography. Then their interaction with calf thymus deoxyribonucleic acid (CT-DNA) and bovine serum albumin (BSA) was explored using absorption and emission spectral methods. The inner filter effect was corrected to get accurate data. Ligand (1) and complex (3) bind strongly to DNA via intercalation and complex (2) binds to it by groove binding mode. The binding modes were further confirmed by CD spectra. BSA binding aspects of synthesized compounds have been studied through various biophysical techniques, and the efficiency of energy transfer between them and BSA has been calculated according to Förster energy transfer theory (FRET). Furthermore, they were assessed for in vitro cytotoxicity testing on the colon carcinoma (CT26) and breast cancer (4T1) cell lines. The three compounds displayed better cytotoxic profiles against CT26 than 4T1 cancer cell lines. Also, their ability to cleave PUC57 plasmid DNA was investigated. Finally, the interaction of ligand (1) with DNA and BSA has been substantiated through molecular docking and a promising intercalation binding efficacy has been revealed for it.