Spectroscopic Investigation on the Binding of the Antitumoral Pd(II) Complex to Human Serum Albumin

Biological effect and molecular docking of anticancer palladium and platinum complexes with morpholine dithiocarbamate on human serum albumin as a blood carrier protein

The aim of this study was to examine the interaction of [Pd(2,2'-bipyridine) (morpholinedithiocarbamate)]NO₃ and [Pt (2,2'-bipyridine)(morpholinedithiocarbamate)]NO₃ with human serum albumin under physiological conditions by using fluorescence, absorption, and circular dichroism spectroscopic techniques. Spectroscopic analysis of the emission quenching at different temperatures demonstrated that the quenching mechanism was static quenching. From the circular dichroism results, thermal stability study, it was found that the interaction of the complexes with human serum albumin caused a conformational change of the protein reversibly. These 2 anticancer Pd and Pt complexes were activated against chronic myelogenous leukemia cell line K562, so that 50% cytotoxic concentration values of 16 and 26 μM for Pd and Pt complexes, respectively, were observed, which were much lower than that of cisplatin (154 μM). Biological activities of both Pd and Pt complexes were also assayed against selective microorganisms by the disc diffusion method. These results showed that the Pd(II) complex is antifungal agent but Pt(II) complex has antibacterial activity. Also, the interaction of both metal derivative complexes was studied by molecular docking. Complementary molecular docking results may be useful to determine the binding mechanism of human serum albumin in pharmaceutical and biophysical studies providing new insight in the novel pharmacology.

Investigation of the interaction between human serum albumin and antitumor palladium(II) complex containing 1,10-phenanthroline and dithiocarbamate ligands

The interaction between [Pd(But-dtc)(phen)]NO3 (where But-dtc = butyldithiocarbamate and phen = 1,10-phenanthroline) with HSA (Human Serum Albumin) was investigated by applying fluorescence, UV-Vis and circular dichroism techniques under physiological conditions. The results of fluorescence spectra indicated that the Pd(II) complex could effectively quench the fluorescence intensity of HSA molecules via static mechanism. The number of binding sites and binding constant of HSA-Pd(II) complex were calculated. Analysis of absorption titration data on the interaction between Pd(II) complex and HSA revealed the formation of HSA-Pd(II) complex with high-binding affinity. Thermodynamic parameters indicated that hydrophobic forces play a major role in this interaction. Furthermore, CD measurements were taken to explore changes in HSA secondary structure induced by the Pd(II) complex.