DNA and BSA Binding Studies of New Pd(II) Bisthiocarbohydrazone Complexes: From Anticancer Drug Analogue to Anticovid Candidates

Abstract

Two new Pd(II) complexes derived from bioactive 1,5-bis(2-benzoylpyridine)thiocarbohydrazone (1) and 1,5-bis(di(2-pyridyl)ketone)thiocarbohydrazone (2) are found to have high putative propensity to the active sites of the SARS-CoV-2 viral protease Mpro compared to active repurposed drugs. The complexes were physicochemically characterized and their solid state band gaps (Eg) were determined. The DFT calculations corroborate with the experimental data and provide insight about their possible chemical and biological reactivity. Both the complexes showed enhanced in vitro cytotoxicity against DLA tumor cells with their increasing concentration. The in silico molecular docking studies of the palladium(II) complexes with the biomolecules duplex DNA and BSA protein exhibit good binding affinity. The interaction ability of these complexes with calf thymus DNA and BSA protein are explored. The absorption spectral study of the interaction with CT-DNA reveals that both the complexes effectively bind with DNA and the fluorescence spectral study confirms the groove mode of binding. The complex 2 having pyridyl groups in place of phenyl groups as compared to the complex 1, binds DNA more effectively. Both the complexes were found to have strong interactions with BSA protein also. The complex 2 again has more affinity for BSA protein based on experimental binding and quenching constant values and the putative molecular docking studies. The binding potential of both the complexes with the Omicron spike protein was also investigated and found to have a comparable efficiency with its controls ivermectin and levosalbutamol.