On the cytotoxic activity of Pd(II) complexes of N,N-disubstituted-N'-acyl thioureas

Pd(II)/diphosphine/curcumin complexes as potential anticancer agents

Palladium(II) complexes have stimulated research interest mainly due to their in vitro cytotoxicity against various cancer cell lines and their low cytotoxicity in healthy cells. Thus, in this work, we combined Pd(II)/phosphine systems with the natural product curcumin as a ligand, obtaining a series of complexes, [Pd(cur)(PPh3)2]PF6 (A1), [Pd(cur)(dppe)]PF6 (A2), [Pd(cur)(dppp)]PF6 (A3), [Pd(cur)(dppb)]PF6 (A4) and [Pd(cur)(dppf)]PF6 (A5), where dppe = 1,2-bis(diphenylphosphino)ethane, dppp = 1,3-bis(diphenylphosphino)propane, dppb = 1,4-bis(diphenylphosphino)butane, and dppf = 1,1'-bis(diphenylphosphino)ferrocene (P-P), which were characterized by elemental analysis, molar conductivity analysis, and mass, NMR (1H, 13C, 31P{1H}), UV-vis, and IR spectroscopies, and four of them (A1, A2, A4, and A5) by X-ray crystallography. The in vitro cell viability of the complexes A1-A5, cisplatin, and the free ligand curcumin against MDA-MB-231 (human triple-negative breast tumor cells), SK-BR-3 (human breast tumor cells), A549 (human lung tumor cells), MRC-5 (non-tumor human lung cells), A2780 (human ovarian carcinoma cells), and A2780cis (cisplatin-resistant human ovarian carcinoma cells), was evaluated by the MTT colorimetric assay. For the tumor cell lines tested, the complexes showed good anticancer activities. The results showed that in general the complexes had lower IC50 values than free curcumin and the precursors [PdCl2(P-P)]. IC50 results obtained for the A1-A5 complexes, in the MCF-7 cell line, are similar to those that had already been observed for some Pd/bipy/curcumin complexes. In the MDA-MB-231 cell line, complexes A1 and A5 stood out, with their lowest IC50 values, around 5 μmol L-1, and the complexes appeared to be more active (lower IC50 values) against the ovarian cell lines. Complex A1 was 23 and 22-fold more cytotoxic than cisplatin, against the A2780 and A2780cis cells, respectively. The complex A1 was studied on A2780cis cells and it was found that this complex inhibits colony formation and induces cell cycle arrest in the sub-G1 phase in a concentration-dependent manner and leads to cell death by apoptosis. The DCFDA assay revealed a potent ROS induction for complex A1.

Cytotoxic and antiparasitic activities of diphosphine-metal complexes of group 10 containing acylthiourea as ligands

In this work, group 10 transition metal complexes bearing dppe [1,2-bis(diphenylphosphino)ethane] and acylthiourea ligands were evaluated for their cytotoxic and antiparasitic activities. Six new complexes with a general formula [M(L_n)(dppe)]BF₄ [where M = Ni^II, Pd^II or Pt^II; L_n = N, N'-dimethyl-N-benzoyl thiourea (L₁) or N, N'-dimethyl-N-tiofenyl thiourea (L₂) were synthesized and characterized by infrared, NMR (³¹P{¹H}, ¹H and ¹³C{¹H}) spectroscopies, elemental analysis and molar conductivity. The structures of the complexes were confirmed by X-ray diffraction technique. The biological activity of the complexes was evaluated on breast cancer cells (MDA-MB-231 and MCF-7) and causative agents of chagas disease and leishmaniasis. The complexes presented higher cytotoxicity for breast cancer cell lines compared to non-tumor cells. Nickel complexes stood out when evaluated against the triple-negative breast cancer line (MDA-MB-231), presenting considerably lower IC₅₀ values (about 10 to 22×), when compared to palladium and platinum complexes, and the cisplatin drug. When evaluated on the triple-negative line (MDA-MB-231), the complexes [Ni(L₂)(dppe)]BF₄(2), [Pd(L₂)(dppe)]BF₄(4) and [Pt(L₂)(dppe)]BF₄(6) were able to induce cell morphological changes, influence on the cell colony formation and the size of the cells. The complexes inhibit cell migration and cause changes to the cell cytoskeleton and nuclear arrangement. In the same cell line, the compounds caused cell arrest in the Sub-G1 phase of the cell cycle. The compounds were also tested against the Trypanosom Cruzi (T. cruzi) and Leishmania sp. parasites, which cause Chagas and leishmaniasis disease, respectively. The compounds showed good anti-parasitic activity, mainly for T. cruzi, with lower IC₅₀ values, when compared to the commercial drug, benznidazole. The compounds interact with CT-DNA, indicating that interaction occurs by the minor groove of the biomolecule.

Antitumor Activity of Palladium(II) Complexes on DU-145 Cell Line in Vitro

In the area of non-platinum complexes, various complexes containing gold, copper, ruthenium, and palladium have shown a strong cytotoxic effect on different cancer cell lines. The aim of our study was to examine the cytotoxicity of the Pd(II) complexes (C1-C5) and the corresponding ligands (L1-L5) on the DU-145 prostate cancer cell line. Also, due to its clinical application, the cytotoxicity of cisplatin has been examined. Our findings showed that C1- C5 complexes and cisplatin show dose-dependent and strong cytotoxic effects against the DU-145 cell line in vitro. Furthermore, the results demonstrated that early apoptosis was induced by all five Pd(II) complexes. Also, the results showed that complexes C1, C3, and C5 induced G0/G1 phase arrest on DU- 145 cells. Pd(II) complex C2 induced S phase arrest, while C4 complex induced G2/M phase arrest on cancer cells. Additionally, all tested complexes significantly reduced the amount of antiapoptotic protein Bcl-2. Also, there was a significant increase in the concentration of proapoptotic Bax protein in DU-145 cells treated C1-C5 complexes. The results of our research demonstrated that Pd(II) complexes induced apoptosis via the mitochondrial pathway. Thus, it is crucial to further investigate the cytotoxicity of these Pd(II) complexes in vivo. Complex C2 might be a good candidate for a new generation of anticancer drugs.

Biological properties and conformational studies of amphiphilic Pd(II) and Ni(II) complexes bearing functionalized aroylaminocarbo-N-thioylpyrrolinate units

A series of novel palladium(II) and nickel(II) complexes of multifunctionalized aroylaminocarbo-N-thioylpyrrolinates were synthesized and characterized by analytical and spectroscopic techniques. The biological properties of the freshly prepared compounds were screened against S. aureus, B. subtilis, A. hydrophila, E. coli, and A. baumannii bacteria and antituberculosis activity against M. tuberculosis H37Rv strains. Also, the antifungal activity was studied against C. albicans, C. tropicalis, and C. glabrata standard strains. A deep conformational survey was monitored using DFT calculations with the aim to explain the importance of the final conformation in the biological experimental results.

meso-Tetra-(4-pyridyl)porphyrin/palladium(II) complexes as anticancer agents

This study reports the synthesis, structural characterization and cytotoxic activity of four new palladium/pyridylporphyrin complexes, with the general formula {TPyP[PdCl(P-P)]₄}(PF₆)₄, where P-P is 1,2-bis(diphenylphosphino)ethane (dppe), 1,3-bis(diphenylphosphino)propane (dppp), 1,2-bis(diphenylphosphino)butane (dppb) or 1,1'-bis(diphenylphosphino)ferrocene (dppf). The complexes were characterized by elemental analysis, and by FT-IR, UV/Vis, ¹H and ³¹P{¹H} NMR (1D/2D) spectroscopy. The slow evaporation of a methanolic solution of {TPyP[PdCl(dppb)]₄}(PF₆)₄ (in an excess of NaBF₄ salt) resulted in single crystals suitable for X ray diffraction, allowing the determination of the tridimensional structure of this complex, which crystallized in the P2₁/a space group. The cytotoxicity of the complexes against MDA-MB-231 (breast cancer cells) and MCF-10A (non-tumor breast cancer cells), was determined by the colorimetric MTT method, which revealed that all four complexes show selective indexes close to 1.2, lower than that of cisplatin for the same cells (12.12). The interaction of the complexes with CT-DNA was evaluated by UV-visible and viscosity measurements and it was determined that the complexes interact moderately with CT-DNA, probably by H-bonding/π-π stacking and electrostatic interactions.

The Cytotoxic Effect of Copper (II) Complexes with Halogenated 1,3-Disubstituted Arylthioureas on Cancer and Bacterial Cells

A series of eight copper (II) complexes with 3-(4-chloro-3-nitrophenyl)thiourea were designed and synthesized. The cytotoxic activity of all compounds was assessed in three human cancer cell lines (SW480, SW620, PC3) and human normal keratinocytes (HaCaT). The complexes 1, 3, 5, 7 and 8 were cytotoxic to the studied tumor cells in the low micromolar range, without affecting the normal cells. The complexes 1, 3, 7 and 8 induced lactate dehydrogenase (LDH) release in all cancer cell lines, but not in the HaCaT cells. They provoked early apoptosis in pathological cells, especially in SW480 and PC3 cells. The ability of compounds 1, 3, 7 and 8 to diminish interleukin-6 (IL-6) concentration in a cell was established. For the first time, the influence of the most promising Cu (II) complexes on intensities of detoxifying and reactive oxygen species (ROS) scavenging the enzymes of tumor cells was studied. The cytotoxic effect of all copper (II) conjugates against standard and hospital bacterial strains was also proved.

Investigation of the reactivity properties of a thiourea derivative with anticancer activity by DFT and MD simulations

Spectroscopic analysis of 1-(2-fluorophenyl)-3-[3-(trifluoromethyl)phenyl]thiourea (FPTT) is reported. Experimental and theoretical analyses of FPTT, with molecular dynamics (MD) simulations, are reported for finding different parameters like identification of suitable excipients, interactions with water, and sensitivity towards autoxidation. Molecular dynamics and docking show that FPTT can act as a potential inhibitor for new drug. Additionally, local reactivity, interactivity with water, and compatibility of FPTT molecule with frequently used excipients have been studied by combined application of density functional theory (DFT) and MD simulations. Analysis of local reactivity has been performed based on selected fundamental quantum-molecular descriptors, while interactivity with water was studied by calculations of radial distribution functions (RDFs). Compatibility with excipients has been assessed through calculations of solubility parameters, applying MD simulations. Graphical abstract Reactive sites identified.

Synthesis, antifungal activity and 3D-QSAR study of novel acyl thiourea compounds containing gem-dimethylcyclopropane ring

A series of novel acyl thiourea compounds containing gem-dimethylcyclopropane ring were designed and synthesized by multi-step reactions in search of novel antifungal molecules. Structures of all the target compounds were characterized by spectral techniques of UV-vis, FT-IR, ¹H-NMR, ¹³C-NMR, and ESI-MS. The antifungal activity of the target compounds was preliminarily evaluated by agar dilution method. The antifungal bioassay revealed that, at 50 μg/mL, compounds 5h (R = o-F), 5m (R = p-Br), and 5n (R = o-NO₂) showed the same antifungal activity of 73.6% against Physalospora piricola, which was comparable than that of the positive control. Furthermore, against Gibberella zeae, compounds 5k (R = m-Cl), 5l (R = m-Br), 5m (R = p-Br), and 5n (R = o-NO₂) displayed the same antifungal activity of 75.6%, and compound 5o (R = p-NO₂) displayed antifungal activity of 78.8%, which were all better than that of the positive control. The preliminary analysis of 3D-QSAR model was performed to study the effect of molecular structure on biological activity using the comparative molecular field analysis (CoMFA) method. The results showed 3D-QSAR model (r² = 0.995, q² = 0.503) was reasonable and effective.

Photoactive PtII and PdII complexes of N,N-diethyl-N′-3,4,5-trimethoxybenzoylthiourea: synthesis, crystal structures, DFT and cytotoxicity studies

New trans-Pd^II/Pt^II acylthiourea complexes prepared by photo-induced isomerism are found to be more cytotoxic than cis-Pd^II/Pt^II against human prostate cancer and normal embryonic kidney cell lines.

Reversible photo-isomerization of cis-[Pd(L-κS,O)2] (HL = N,N-diethyl-N'-1-naphthoylthiourea) to trans-[Pd(L-κS,O)2] and the unprecedented formation of trans-[Pd(L-κS,N)2] in solution

Upon ex situ UV-visible light irradiation, complex cis-bis(N,N-diethyl-N'-naphthoylthioureato)-palladium(ii), cis-[Pd(L-κS,O)2], undergoes isomerization in acetonitrile-d3 and chloroform-d to yield trans-[Pd(L-κS,O)2] which then rearranges thermally to novel trans-[Pd(L-κS,N)2] prior to reverting thermally to the cis isomer in the absence of light. The thermal isomerization rate is highly solvent dependent and harnessed to enable each of these three geometric isomers to be isolated and characterized by 1H NMR spectroscopy, X-ray crystallography, melting point and thermal analysis. The formation of the trans-[Pd(L-κS,N)2] isomer as part of this isomerization has only been observed with the sterically demanding cis-bis(N,N-diethyl-N'-(naphthoylthioureato)palladium(ii) precursor based on our knowledge to date. In situ irradiation with monochromatic laser light (λ = 355 nm) coupled to 1H NMR spectroscopy of solutions of cis-[Pd(L-κS,O)2] in acetonitrile-d3 supports the ex situ photo-induced isomerization experiments.

Synthesis and Anticancer Activity of [RuCl2(η6-arene)(aroylthiourea)] Complexes-High Activity against the Human Neuroblastoma (IMR-32) Cancer Cell Line

Eight new organometallic Ru(II)-arene complexes of the type [RuCl₂(η⁶-arene)(η¹-S-aroylthiourea)] (arene = p-cymene or benzene) were synthesized in order to evaluate the effect of the arene moiety and the substituent of the aroylthiourea ligand on the cytotoxicity of the complexes. The ligands (L1 and L2) and complexes (1-8) were characterized using analytical and spectroscopic (UV-visible, infrared, ¹H NMR, ¹³C NMR, and mass) methods. The structure of the ligands (L1 and L2) and complexes (1 and 3-6) was obtained from single-crystal X-ray diffraction studies. The cytotoxicity of the complexes was evaluated against four different cancer cell lines: MCF-7 (breast), COLO 205 (colon), A549 (lung), and IMR-32 (neuroblastoma). All the complexes showed good cytotoxicity and the highest was in the IMR-32 cell line, which articulates the specificity of these complexes toward the IMR-32 cancer cell line. The complexes 5, 7, and 8 exhibited remarkable cytotoxicity in the entire cancer cell lines tested, which was comparable with the standard drug, cisplatin. The anticancer mechanism of the complexes 3 and 7 in IMR-32 cells was evaluated by bright-field microscopy, intracellular reactive oxygen species (ROS), mitochondrial membrane potential (MMP), DNA damage, and caspase-3 analyses. The cells treated with the complexes showed upregulated caspase-3 compared to the control, and it was found that ROS and MMP were dose-dependent on analysis. Also, bright-field microscopy and 4',6-diamidino-2-phenylindole (DAPI) staining have correspondingly shown cellular membrane blebbing and DNA damage, which were morphological hallmarks of apoptosis. The study concluded that the complexes promoted the oxidative stress-mediated apoptotic death of the cancer cells through the generation of intracellular ROS, depletion of MMP, and damage of the nuclear material.

Anticancer activity of palladium-based complexes against triple-negative breast cancer

Treatment of triple-negative breast carcinoma (TNBC) remains an unmet medical need with no targeted therapy available to date. Accounting for 10-30% of all human breast cancer tumors, this mammary carcinoma subtype has a particularly poor prognosis owing to its high metastatic potential, aggressive biology and limited pharmacological treatment options. Platinum chemotherapeutics are the mainstay therapy in patients with TNBC but their clinical use is limited by severe toxicity and acquired resistance. Palladium-based complexes are appealing alternative metal-based drugs because of significant similarities regarding structure and coordination chemistry with the platinum agents. This review summarizes the knowledge gathered so far on 121 Pd(II) complexes, emphasizing their anticancer activity and putative pharmacological targets toward TNBC.

Disubstituted 4-Chloro-3-nitrophenylthiourea Derivatives: Antimicrobial and Cytotoxic Studies

4-Chloro-3-nitrophenylthioureas 1–30 were synthesized and tested for their antimicrobial and cytotoxic activities. Compounds exhibited high to moderate antistaphylococcal activity against both standard and clinical strains (MIC values 2–64 μg/mL). Among them derivatives with electron-donating alkyl substituents at the phenyl ring were the most promising. Moreover, compounds 1–6 and 8–19 were cytotoxic against MT-4 cells and various other cell lines derived from human hematological tumors (CC₅₀ ≤ 10 μM). The influence of derivatives 11, 13 and 25 on viability, mortality and the growth rate of immortalized human keratinocytes (HaCaT) was observed.

Synthesis, structural and antimicrobial studies of type II topoisomerase-targeted copper(II) complexes of 1,3-disubstituted thiourea ligands

A series of Cu(II) complexes of 3-(trifluoromethyl)phenylthiourea derivatives was synthesized. Their structural properties were investigated by spectroscopic techniques (infrared and electron paramagnetic resonance), as well as molecular modeling. All studied coordination compounds are mononuclear complexes containing two chelating ligands bonded to the metal cation via S and deprotonated N atoms. The new chelates were evaluated for their antimicrobial potency. The complex of 1-(3,4-dichlorophenyl)-3-[3-(trifluoromethyl)phenyl]thiourea (3) presented the highest activity against Gram-positive pathogens, even stronger than the activity of its non-complexed counterpart and the reference drug. The compound also prevented the biofilm formation of methicillin-resistant and standard strains of staphylococcal cocci. The title derivatives were found to be effective inhibitors of DNA gyrase and topoisomerase IV isolated from Staphylococcus aureus. The binding modes of the ligand L3 with DNA gyrase and topoisomerase IV were presented.

Synthesis, characterization, computational and antimicrobial activities of a novel iridium thiourea complex

A novel octahedral iridium(iii)thiourea complex with potential medical applications.

Half sandwich Ru(ii)-acylthiourea complexes: DNA/HSA-binding, anti-migration and cell death in a human breast tumor cell line

Eight Ru(ii) complexes were synthesized. The activities against MDA-MB-231 cells include anti-migration, arrest at the sub-G1 phase and cell death by apoptosis.