A couple of antitumor Pd(II) complexes make DNA-refolding and HSA-unfolding: Experimental and docking studies

Two novel Pd(II) complexes, [Pd(pn)(SA)] (I) and [Pd(pn)(SSA)] (II)) pn = propylenediamine, SA = salicylate and SSA = sulfosalicylate (were made and characterized by spectroscopic techniques (UV-Vis, FT-IR and H-1 NMR), elemental analysis (CHNS) and molar conductivity measurements. They are Pd(II) analogs of the well-known anticancer drugs viz carboplatin and oxaliplatin, where two cis donor atoms are nitrogen and the other two are oxygen in a near square planar array. In-vitro antitumor activity of these compounds against K562 cancer cell line were evaluated via MTT assay and showed promising activities. Their interaction with calf thymus DNA (CT-DNA) and human serum albumin (HSA) was assessed by electronic absorption, fluorescence, gel electrophoresis and circular dichroism techniques. For both biomolecules, the fluorescence quenching occurs through static procedure. CT-DNA- and HSA-binding affinities of the complexes is in the order of (I) < (II) and they effectively interact with these biomolecules at very low concentrations. The negative sign of DS degrees and DH degrees calculated from the fluorescence studies indicated that van der Waals and hydrogen-bond forces hold the complexes in the grooves of CT-DNA and or possibly in the main binding pocket of HSA. In-silico molecular docking calculation revealed the minor groove binding of both complexes with DNA and supported the higher binding affinity of complex (II) towards DNA. It also confirmed the insertion of both complexes in the site I of HSA. (C) 2022 Elsevier B.V. All rights reserved.