Synthesis of tetranuclear cyclopalladated complex using thiosemicarbazone derivative ligand: Spectral, biological and molecular docking studies

Abstract

New tetranuclear Palladium(II) complex, (Pd-(OMe)-TSC)4, has been successfully synthesized from the reaction of potassium tetrachloridopalladate (II) salt (K2[PdCl4]) with methoxy‑functionalized thiosemicarbazone ligand, OMe-TSC, and characterized using various spectroscopic techniques such as FT-IR, UV–Vis, 1H NMR, 13C NMR, 1H-1H COSY, 13C-APT, 1H-13C HMQC, elemental analyses and high-resolution mass spectroscopy. The in-vitro anticancer activity was investigated by using MTT test in breast cancer cells (MCF-7 cell line). Anticancer activity of the complex was higher than ligand and the results inferred that the complex showed comparable activitiy with cis-platin. Furthermore, fluorescence and UV–Vis spectroscopies had been used to investigate the binding interaction of the synthesized samples with Bovine Serum Albumin (BSA). Three different drugs namely, Warfarin, Ibuprofen, and Digoxin, were employed to study the competitive bindings to different sites on BSA. The obtained results demonstrated that the binding sites were mainly located within site I and II of BSA for the (Pd-(OMe)-TSC)4 complex and (OMe)-TSC ligand, respectively. In addition, the suggested structures of ligand and complex have been optimized by semi-emprical method and the aforementioned results of BSA interaction were supported by molecular docking and molecular dynamics calculations. Also, The free binding energies of -4.16 kcal/mol and -5.80 kcal/mol were calculated for the interaction of the ligand and complex with SARS-CoV-2, respectively, which indicated the interaction is a spontaneous process and is a evidence for antiviral potential of (Pd-(OMe)-TSC)4 complex.