2,2'-Bipyridinebutyldithiocarbamatoplatinum(II) and palladium(II) complexes: synthesis, characterization, cytotoxicity, and rich DNA-binding studies

Preliminary anticancer evaluation of new Pd(II) complexes bearing NNO donor ligands

In this study we presented a novel series of NNO tridentate ligands generating imino, amido and oxo donor pocket for Pd(II) coordination. All the compounds were meticulously characterized by elemental analysis and advanced spectroscopic techniques, including FTIR, proton and carbon NMR. The synthesized compounds underwent rigorous evaluation for their potential as anti-cancer agents, utilizing the aggressive breast cancer cell lines MDA-MB (ATCC) and MCF-7 as a crucial model for assessing growth inhibition in cancer cells. Remarkably, the MTT assay unveiled the robust anti-cancer activity for all palladium complexes against MDA-MB-231 and MCF-7 cells. Particularly, complex [Pd(L1)(CH3CN)] exhibited exceptional potency with an IC50 value of 25.50 ± 0.30 µM (MDA-MB-231) and 20.76 ± 0.30 µM (MCF-7), compared to respective 27.00 ± 0.80 µM and 24.10 ± 0.80 µM for cisplatin, underscoring its promising therapeutic potential. Furthermore, to elucidate the mechanistic basis for the anti-cancer effects, molecular docking studies on tyrosine kinases, an integral target in cancer research, were carried out. The outcome of these investigations further substantiated the remarkable anticancer properties inherent to these innovative compounds. This research offers a compelling perspective on the development of potent anti-cancer agents rooted in the synergy between ligands and Pd(II) complexes and presenting a promising avenue for future cancer therapy endeavors.

Biological interaction of Pt complex with imidazole derivative as an anticancer compound with DNA: Experimental and theoretical studies

This investigation is applied to find out interesting information on DNA binding mode with Pt(II) derivative of two N, N bidentate ligands in treating cancer. Thus, one new water-soluble platinum complex with FIP and phen with a new formula of [Pt(phen)(FIP)](NO3)2 was prepared and specified. DFT data can be used to evaluate geometry parameters. Based on the ADMET prediction, this complex can be considered a drug-like agent. Cytotoxicity property was evaluated against some human cancerous MCF7, A549, and HCT116 cell lines. Accumulation of Pt complex, cisplatin, and oxaliplatin in each cancerous cell was determined, which is probably related to their lipophilicity and solubility properties. The binding mode of the complex to ct-DNA was investigated by fluorescence spectroscopy, circular dichroism, and molecular docking simulation. The viscosity of DNA by different concentrations of EB and Pt complex titration shows Pt complex interacts with DNA via groove binding like the spectroscopic binding result. In the MD study, DNA helix, RMSD, and RMSF analysis showed that DNA stability decreased and that the majority of residues left the initial state. DNA increased residual deviations and flexibility are linked to an increase in its gyratory radius, which is consistent with the findings of the experiments.

Electrochemical investigation of DNA-metal complex interactions and development of a highly sensitive electrochemical biosensor

Metal ion-DNA interactions are important in nature as they often change the genetic material's structure and function. In this work, new Tb complex of TbCl₃ (tris(8-hydroxyquinoline-5-sulfonic acid) terbium) (Tb(QS)₃) was used as an electrochemical indicator for investigation of DNA-metal interaction and then a new DNA biosensor was designed using this complex. Cyclic voltammetry (CV) and differential pulse voltammetry (DPV) were used to study the interaction of Tb(QS)₃ with double-stranded DNA (ds-DNA). It was found that Tb(QS)₃ presented an excellent electrochemical activity on carbon paste electrode (CPE) and could intercalate into the double helix of double-stranded DNA. The interaction mechanism was elucidated in DNA solution and DNA modified carbon paste electrode by using differential pulse voltammetry and cyclic voltammetry. The binding ratio between this complex and ds-DNA was calculated to be 1:1. The extent of hybridization was evaluated on the basis of the difference between signals of Tb(QS)₃ with probe DNA before and after hybridization with complementary DNA. With this approach, target DNA could be detected in the range from 0.03 to 0.185 μM with detection limit of 0.021 μM. The interaction mode between Tb(QS)₃ and DNA was found to be mainly intercalative interaction.

Pd(II) complexes with chelating N-(1-alkylpyridin-4(1H)-ylidene)amide (PYA) ligands: Synthesis, characterization and evaluation of anticancer activity

The bidentate N-(1-Alkylpyridin-4(1H)-ylidene)amide (PYA) pro-ligands [H₂L_Bn][Cl]₂ (2), and [H₂L_Me][TfO]₂ (3) were prepared by simple alkylation reactions of the known compound, N,N-di(pyridin-4-yl)oxalamide (H₂L, 1). The Pd(II) complexes, [Pd(L_Bn)₂][Cl]₂ (4), [Pd(L_Me)₂][Cl][TfO] (5), Pd(L_Bn)Cl₂ (6) and Pd(L_Me)Cl₂ (7) were synthesized through reactions between these pro-ligands and suitable Pd(II) substrates in the presence of base. The molecular structures of 3 and 6 were obtained by single crystal X-ray structure determinations. Studies of the experimental and computational DNA binding interactions of the compounds 1-7 revealed that overall 4 and 6 have the largest values for the binding parameters K_b and ΔG_b^o. The results showed a good correlation with the steric and electronic parameters obtained by quantitative structure activity relationship (QSAR) studies. In-vitro cytotoxicity studies against four different cell lines showed that the human breast cancer cell lines MCF-7, T47D and cervical cancer cell line HeLa had either higher or similar sensitivities towards 4, 6 and 2, respectively, compared to cisplatin. In general, the cytotoxicity of the compounds, represented by IC₅₀ values, decreased in the order 4 > 6 > 2 > 5 > 3 > 1 > 7 in cancer cell lines. Apoptosis contributed significantly to the cytotoxic effects of these anticancer agents as evaluated by apoptosis studies.

A new palladium-based antiproliferative agent: synthesis, characterization, computational calculations, cytotoxicity, and DNA binding properties

A new palladium(II) complex entitled [Pd(phendione)(8Q)]NO₃, (PdPQ), where phendione is N,N-donor heterocyclic 1,10-phenanthroline-5,6-dion and 8Q is 8-hydroxyquinolinate, has been synthesized and then characterized by molar conductivity, CHN analysis and spectral data (UV-Vis, FT-IR, NMR). DFT/ TDDFT procedures were also performed to determine the electronic structure and the nature of the electronic transitions of PdPQ. Moreover, the affinity and binding properties of DNA to the desired complex have been studied in details using electronic absorption, fluorescence, circular dichroism spectroscopies, and viscosity measurement in combination with molecular docking technique. The obtained results exhibit relatively high DNA binding values with a static quenching mechanism, which suggest that an intercalative mode plays a peridominate role in interaction process concluded by experimental/theoretical measurements. As a result of drug exposure, in vitro cytotoxicity assay demonstrated the antiproliferative activity of the PdPQ against leukemia cancer cell line, K562.

New anticancer Pd and Pt complexes of tertamyl dithiocarbamate and DACH ligands against HT29 and Panc1 cell lines

To investigate the reduction of side effects of commercial antitumor drugs such as cisplatin, two new platinum and palladium complexes with a formula of [M(DACH)(tertamyl.dtc)]NO₃ were synthesized (DACH is 1R, 2R-diaminocyclohexane, tertamyl-dtc is tertpentyl dithiocarbamate, and M is palladium or platin ionic metals) and characterized by spectroscopic methods. The in vitro cytotoxicity of these compounds against HT29 and Panc1 cell lines showed that the IC₅₀ values against Panc1 cell line of [Pt(DACH)(tertamyl.dtc)]NO₃ and [Pd(DACH)(tertamyl.dtc)]NO₃ were 263.1 and 198.7 µM, and also against HT29 cell line were 241.9 and 258.2 µM, respectively. They were similar to the value obtained for oxaliplatin and lower than cisplatin value. Thermal stability and circular dichroism results demonstrated that both metal complexes could bind to DNA via electrostatic bonds. Due to electrostatic interaction, the configuration of B-DNA to C-DNA changed, though the possibility of groove interaction may be strengthened. Furthermore, molecular docking simulation showed higher negative docking energy for [Pd(DACH)(tertamyl.dtc)]NO₃ complex with a higher tendency for DNA interaction. In vitro cytotoxicity of two new Pt and Pd compounds have been studied against two cell lines (HT29 and Panc 1), which are almost equal to the value obtained for oxaliplatin and they are lower than cisplatin value. Thermal stability studies and CD results demonstrated that both complexes bind to DNA via electrostatic bonds. Further, molecular docking showed higher negative docking energy for [Pd(DACH)(tertamyl.dtc)]NO3 complex with a higher tendency for interaction.Communicated by Ramaswamy H. Sarma.

Arsenic(III) mixed derivatives having oximes and morpholinedithiocarbamate along with their cytotoxic, antimicrobial, and antioxidant studies

Consecutive substitution reactions of arsenic(III)chloride with sodium salts of various oximes and morpholinedithiocarbamate (morphdtc) were carried out in 1:2:1 stoichiometry to obtain six new arsenic(III) mixed derivatives of the type: [(R)(R¹ )C = NO]₂ Sb[S₂ CN(CH₂ CH₂ )₂ O] [where R is -C₆ H₅ , R¹  = -CH₃ (1); R = -C₆ H₄ CH₃ , R¹  = -CH₃ (2); R = -C₆ H₄ Cl, R¹  = -CH₃ (3); R = -C₆ H₄ Br, R¹  = -CH₃ (4); R = -C₆ H₄ OH, R¹  = -H (5); R(R¹ )C =  (6)]. These derivatives are characterized by elemental and physicochemical analyses and the tentative distorted trigonalbipyramidal geometry around arsenic assigned using spectral data of infrared (¹ H, ¹³ C) nuclear magnetic resonance and liquid chromatography-mass. Powder X-ray diffraction study revealed their nanoranged particle size to be approximately 40 nm and crystalline nature. These derivatives examined against microbes and results revealed that these derivatives expressed more antifungal potential than antibacterial. The antioxidant activity was carried out by ferric reducing ability of plasma assay, and the cytotoxic study was performed in 3T₃ fibroblast cell lines by tetrazolium-based colorimetric assay.

Bimetallic DppfM(II) (M = Pt and Pd) dithiocarbamate complexes: Synthesis, characterization, and anticancer activity

A series of bimetallic dppfM(II) (dppf = 1,1’-bis (diphenyphosphino) ferrocene; M = Pt and Pd) dithiocarbamate complexes is synthesized and characterized by spectroscopic methods and single-crystal X-ray diffraction. Their antitumor activities in vitro are investigated by MTT assays against four cancer cell lines. The anticancer studies indicate most of the complexes display good to excellent antitumor activity. Remarkably, the platinum complex with a pyrrolidinyl substituent (3b) was identified as the most promising candidate due to its high potency and broad spectrum of activity.

Some new anticancer platinum complexes of dithiocarbamate derivatives against human colorectal and pancreatic cell lines

Cisplatin, carboplatin and oxaliplatin and their analogs are effective anticancer agents, but their clinical using is limited by some serious side effects. S,S donor ligands such as dithiocarbamates can be used to reduce some side effects. In this study, some novel water soluble complexes with formula of [Pt(bpy)(R.dtc)]NO₃, where bpy is bipyridine and R.dtc is amyl-, isopentyl- or tertamyl-dtc (n-pentyl-, 3-metyl-butyl- and 2-methylbutan-dithiocarbamate, respectively) have been synthesized and characterized by elemental analysis, conductivity measurements and chemical analysis. The cytotoxic activities of synthesized complexes were investigated against human adenocarcinoma colorectal cell line (HT29) and human pancreatic cell line (Panc1), and compared with cisplatin and oxaliplatin, which display more anticancer activity for [Pt(bpy)(isopentyl.dtc)]NO₃. The experimental fluorescence and circular dichroism results illustrated partially groove binding of [Pt(bpy)(amyl.dtc)]NO₃ and [Pt(bpy)isopentyl.dtc)]NO₃ on DNA, while [Pt(bpy)(tertamyl.dtc)]NO₃ complex, can bind to DNA via intercalation. Finally, molecular docking simulation data of DNA interaction with three synthesized complexes showed [Pt(bpy)(amyl.dtc)]NO₃ complex has the highest tendency and negative docking energy in structural change of DNA.Communicated by Ramaswamy H. Sarma.

Cooperativity effect of the ππ interaction between drug and DNA on intercalative binding induced by H-bonds: a QM/QTAIM investigation of the curcuminadenineH2O model system

In order to reveal the nature of intercalative binding of drug to DNA, the cooperativity effect of the ππ interaction was investigated in the curcuminadenineH2O model system by applying a combined QM and QTAIM computational approach. The H-bonds between the electron-donating group of curcumin and adenine induce the formation of the ππ stacking. The introduction of H2O weakens the H-bonding and ππ interactions, leading to an anti-cooperativity effect, as is confirmed by the AIM (atoms in molecules) and RDG (reduced density gradient) analysis. Thus, it can be inferred that the anti-cooperative effect is the main driving force for the intercalative binding of drug to DNA bases, which is in agreement with many experimental phenomena. Therefore, the designed DNA-targeted intercalating drugs should possess not only hydrophobic moieties, but also strong electron-donating groups bound to the DNA bases with H-bonds, which can slow the variation rates of the strengths of the H-bonding and ππ interactions between drug and DNA bases in the anti-cooperative process, leading to the intercalation formation. The enthalpy change is the major factor driving the positive thermodynamic cooperativity.

Nonionic but water soluble, [Glycine-Pd-Alanine] and [Glycine-Pd-Valine] complexes. Their synthesis, characterization, antitumor activities and rich DNA/HSA interaction studies

Two novel, neutral and water soluble Pd(II) complexes of formula [Pd(Gly)(Ala)] (1) and [Pd(Gly)(Val)] (2) (Gly, Ala, and Val are anionic forms of glycine, alanine, and valine amino acids, respectively) have been synthesized and characterized by FT-IR, UV-Vis, ¹H-NMR, elemental analysis, and molar conductivity measurement. The data revealed that each amino acid binds to Pd(II) through the nitrogen of -NH₂ and the oxygen of -COO^- groups and acts as a bidentate chelate. These complexes have been assayed against leukemia cells (K₅₆₂) using MTT method. The results indicated that both of the complexes display more cytotoxicity than the well-known anticancer drug, cisplatin. The interaction of the compounds with calf thymus DNA (CT-DNA) and human serum albumin (HSA) were assayed by a series of experimental techniques including electronic absorption, fluorescence, viscometry, gel electrophoresis, and FT-IR. The results indicated that the two complexes have interesting binding propensities toward CT-DNA as well as HSA and the binding affinity of (1) is more than (2). The fluorescence data indicated that both complexes strongly quench the fluorescence of ethidium bromide-DNA system as well as the intrinsic fluorescence of HSA via static quenching procedures. The thermodynamic parameters (ΔH°, ΔS°, and ΔG°) calculated from the fluorescence studies showed that hydrogen bonds and van der Waals interactions play a major role in the binding of the complexes to DNA and HSA. We suggest that both of the Pd(II) complexes exhibit the groove binding mode with CT-DNA and interact with the main binding pocket of HSA. Communicated by Ramaswamy H. Sarma.

Biological evaluations of newly-designed Pt(II) and Pd(II) complexes using spectroscopic and molecular docking approaches

To perform biological evaluations of newly-designed Pt(II) and Pd(II) complexes, the present study was conducted with targeted protein human serum albumin (HSA) and HCT116 cell line as model of human colorectal carcinoma. The binding of Pt(II) and Pd(II) complexes to HSA was analyzed using fluorescence spectroscopy and molecular docking. The thermal stability and alterations in the secondary structure of HSA in the presence of Pt(II) and Pd(II) complexes were investigated using the thermal denaturation method and circular dichroism (CD) spectroscopy. The cytotoxicity of the Pt(II) and Pd(II) complexes was studied against the HCT116 cell line using MTT assay. The binding analysis revealed that the fluorescence findings were well in agreement with docking results such that there is only one binding site for each complex on HSA. Binding constants of 8.7 × 10³ M^-1, 2.65 × 10³ M^-1, 0.3 × 10³ M^-1, and 4.4 × 10³ M^-1 were determined for Pd(II) and Pt(II) complexes (I-IV) at temperature of 25 °C, respectively. Also, binding constants of 1.9 × 10³ M^-1, 15.17 × 10³ M^-1, 1.9 × 10³ M^-1, and 13.1 × 10³ M^-1 were determined for Pd(II) and Pt(II) complexes (I-IV) at temperature of 37 °C, respectively. The results of CD and thermal denaturation showed that the molecular structure of HSA affected by interaction with Pt(II) and Pd(II) complexes is stable. Cytotoxicity studies represented the growth suppression effect of the Pt(II) and Pd(II) complexes toward the human colorectal carcinoma cell line. Therefore, the results suggest that the new designed Pt(II) and Pd(II) complexes are well promising candidates for use in cancer treatment, particularly for human colorectal cancer. Communicated by Ramaswamy H. Sarma.

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.

Cooperativity effect involving drug-DNA/RNA intermolecular interaction: A B3LYP-D3 and MP2 theoretical investigation on ketoprofen⋯cytosine⋯H2O system

In order to examine the origin of the drug action and design new DNA/RNA-targeted drugs, the cooperativity effect involving drug-DNA/RNA intermolecular interaction in ketoprofen⋯cytosine⋯H₂O ternary system were investigated by the B3LYP, B3LYP-D3, and MP2 methods with the 6-311++G(2d,p) basis set. The thermodynamic cooperativity was also evaluated at 310.15 K. The N-H⋯O, O-H⋯O, O-H⋯N, C-H⋯N, and C-H⋯O H bonds coexist in ternary complexes. The intermolecular interactions obtained by B3LYP-D3 are close to those calculated by MP2. The steric effects and van der Waals interactions have little influence on the cooperativity effects. The anti-cooperativity effect in ket⋯cyt⋯H₂O is far more notable than the cooperativity effect, and the stability of the cyclic structure with anti-cooperativity effect is higher than that of the linear structure with cooperativity effect, as is confirmed by the AIM (atoms in molecules) and RDG (reduced density gradient) analysis. Thus, it can be inferred that, in the presence of H₂O, the anti-cooperativity effect plays a dominant role in the drug-DNA/RNA interaction, and the nature of the hydration in the binding of drugs to DNA/RNA bases is the H-bonding anti-cooperativity effect. Furthermore, the drug always links simultaneously with DNA/RNA base and H₂O, and only in this way can the biological activity of drugs play a role. In most cases, the enthalpy change is the major factor driving the cooperativity, as is different from most of biomacromolecule complexes.

Controllable synthesis and characterisation of palladium (II) anticancer complex-loaded colloidal gelatin nanoparticles as a novel sustained-release delivery system in cancer therapy

Over the past few years, there have been several attempts to deliver anticancer drugs into the body. It has been shown that compared to other available carriers, colloidal gelatin nanoparticles (CGNPs) have distinct properties due to their exceptional physico-chemical and biological characteristics. In this study, a novel water-soluble palladium (II) anticancer complex was first synthesised, and then loaded into CGNPs. The CGNPs were synthesised through a two-step desolvation method with an average particle size of 378 nm. After confirming the stability of the drug in the nanoparticles, the drug-loaded CGNPs were tested for in vitro cytotoxicity against human breast cancer cells. The results showed that the average drug encapsulating efficiency and drug loading of CGNPs were 64 and 10 ± 2.1% (w/w), respectively. There was a slight shift to higher values of cumulative release, when the samples were tested in lower pH values. In addition, the in vitro cytotoxicity test indicated that the number of growing cells significantly decreased after 48 h in the presence of different concentrations of drug. The results also demonstrated that the released drug could bind to DNA by a static mechanism at low concentrations (0.57 µM) on the basis of hydrophobic and hydrogen binding interactions.

2,2'- bipyridine coplanar with coordination square of Pd(II) nonyldithiocarbamato antitumor complex interacting with DNA in two distinct steps

Cisplatin is one of the most effective chemotherapy drugs, and has been widely employed for more than four decades in the treatment of different forms of human tumors. In recent years, various examples of metal complex-based compounds have been used for medicinal purposes. In this context, the novel palladium(II) complex, [Pd(non-dtc)(bpy)]NO₃, (non-dtc = nonyldithiocarbamate and bpy = 2,2'- bipyridine) has been synthesized and characterized by means of elemental analysis, conductivity measurements, FT-IR, ¹H NMR, ¹³C NMR, and electronic spectroscopy studies. The 50% cytotoxic concentrations (Ic₅₀) of this Pd(II) complex (0.53 mM) and cisplatin (154 mM) against human cell tumor line (K562) indicates its interaction with DNA of cancer cell at quite low concentration. Thus, binding characteristics of this compound to calf thymus DNA (CT-DNA) has been investigated by UV-vis absorption spectroscopy and fluorescence spectra. The exciting observation of this work in the UV-visible studies was that the Pd(II) complex exhibit two or more types of interaction with CT-DNA. Such properties have rarely been observed in the literature. This complex cooperatively binds with DNA and denatures it too. Fluorescence studies proved the intercalation mode of binding and the other modes seems to be hydrophobic and electrostatic interactions. Binding parameters and thermodynamics of the interaction with CT-DNA are also described. Finally, multifunctional interactions of [Pd(non-dtc)(bpy)]NO₃ make it suitable to interact with DNA of cancer cell at quite low concentration and if it is used as anticancer agent, very low doses will be needed which may have fewer side effects.