Synthesis, X-ray structure, DFT calculations and anticancer activity of a selenourea coordinated gold(I)-carbene complex

Au⋅⋅⋅H-X (X=N or C) Intramolecular Interactions in Gold (I)-NHC Carbene Complexes with Potential Anticancer Properties: A Quantum Mechanical Study with Two Basis Sets

Three cationic Gold(I)-NHC complexes with potential anticancer properties were studied using DFT with B3LYP functional in combination with two basis sets, LanL2DZ and SDD. Obtained equilibrium geometries and computed IR spectra were found in excellent agreement with previously reported x-ray structures and experimental IR spectral data. NBO population analysis showed gold(I) has a charge deficiency of 0.26-0.30 e. All three complex cations are polar, with dipole moment values ranging from 6.8 to 7.4 Debye. Regardless of some structural differences in their co-ligands, all three complex cations have remarkably similar HOMO-LUMO energy gaps, with values ranging from 5.2 to 5.4 eV, confirming they are chemically stable and that they share an almost identical stability. Long-range intramolecular interactions Au ⋅⋅⋅H-X (X=N or C) in all three cationic complexes were identified. Both basis sets employed in this study were found equally effective in producing reliable results.

Anticancer Activity of Metallodrugs and Metallizing Host Defense Peptides-Current Developments in Structure-Activity Relationship

This article provides an overview of the development, structure and activity of various metal complexes with anti-cancer activity. Chemical researchers continue to work on the development and synthesis of new molecules that could act as anti-tumor drugs to achieve more favorable therapies. It is therefore important to have information about the various chemotherapeutic substances and their mode of action. This review focuses on metallodrugs that contain a metal as a key structural fragment, with cisplatin paving the way for their chemotherapeutic application. The text also looks at ruthenium complexes, including the therapeutic applications of phosphorescent ruthenium(II) complexes, emphasizing their dual role in therapy and diagnostics. In addition, the antitumor activities of titanium and gold derivatives, their side effects, and ongoing research to improve their efficacy and reduce adverse effects are discussed. Metallization of host defense peptides (HDPs) with various metal ions is also highlighted as a strategy that significantly enhances their anticancer activity by broadening their mechanisms of action.

Dinuclear gold(I) complexes based on carbene and diphosphane ligands: bis[2-(dicyclohexylphosphano)ethyl]amine complex inhibits the proteasome activity, decreases stem cell markers and spheroid viability in lung cancer cells

Three new dinuclear gold(I) complexes (1-3) containing a carbene (1,3-Bis(2,6-di-isopropylphenyl)imidazol-2-ylidene (IPr)) and diphosphane ligands [bis(1,2-diphenylphosphano)ethane (Dppe), bis(1,3-diphenylphosphano)propane (Dppp) and bis[2-(dicyclohexylphosphano)ethyl]amine (DCyPA)], were synthesized and characterized by elemental analysis and, ESI-MS, mid FT-IR and NMR spectroscopic methods. The structures of complexes 2 and 3 were determined by X-ray crystallography, which revealed that the complexes are dinuclear having gold(I) ions linearly coordinated. The anticancer activities of the complexes (1-3) were evaluated in lung (A549), breast (MC-F7), prostate (PC-3), osteosarcoma (MG-63) and ovarian (A2780 and A2780cis) cancer models. Growth inhibition by the new complexes was higher than cisplatin in all cell lines tested. The mechanism of action of complex 3 was investigated in A549 cells using 2-dimensional (2D) models and 3D-multicellular tumor spheroids. Treatment of A549 cells with complex 3 caused: the induction of apoptosis and the generation of reactive oxygen species; the cell cycle arrest in the G0/G1 phase; the inhibition of both the proteasome and the NF-kB activity; the down-regulation of lung cancer stem cell markers (NOTCH1, CD133, ALDH1 and CD44). Complex 3 was more active than cisplatin also in 3D models of A549 lung cancer cells.

Computational Studies of Au(I) and Au(III) Anticancer MetalLodrugs: A Survey

Owing to the growing hardware capabilities and the enhancing efficacy of computational methodologies, computational chemistry approaches have constantly become more important in the development of novel anticancer metallodrugs. Besides traditional Pt-based drugs, inorganic and organometallic complexes of other transition metals are showing increasing potential in the treatment of cancer. Among them, Au(I)- and Au(III)-based compounds are promising candidates due to the strong affinity of Au(I) cations to cysteine and selenocysteine side chains of the protein residues and to Au(III) complexes being more labile and prone to the reduction to either Au(I) or Au(0) in the physiological milieu. A correct prediction of metal complexes' properties and of their bonding interactions with potential ligands requires QM computations, usually at the ab initio or DFT level. However, MM, MD, and docking approaches can also give useful information on their binding site on large biomolecular targets, such as proteins or DNA, provided a careful parametrization of the metal force field is employed. In this review, we provide an overview of the recent computational studies of Au(I) and Au(III) antitumor compounds and of their interactions with biomolecular targets, such as sulfur- and selenium-containing enzymes, like glutathione reductases, glutathione peroxidase, glutathione-S-transferase, cysteine protease, thioredoxin reductase and poly (ADP-ribose) polymerase 1.

Synthesis and in vitro anticancer activities of selenium N-heterocyclic carbene compounds

Fourteen novel selenium N-heterocyclic carbene (Se-NHC) compounds derived from 4,5-diarylimidazole were designed, synthesized, and evaluated as antiproliferative agents. Most of them were more effective toward A2780 ovarian cancer cells than HepG2 hepatocellular carcinoma cells. Among them, the most active compound 2b was about fourfold more active than the positive control ebselen against A2780 cells. In addition, this compound displayed twofold higher cytotoxicity to A2780 cells than to IOSE80 normal ovarian epithelial cells. Further studies revealed that 2b could induce reactive oxygen species production, damage mitochondrial membrane potential, block the cells in the G0/G1 phase, and finally promote A2780 cell apoptosis.

Novel N,N'-Disubstituted Selenoureas as Potential Antioxidant and Cytotoxic Agents

A series of 30 novel N,N disubstituted selenoureas were synthesized, characterized, and their antioxidant ability was tested using 2,2-diphenyl-1-picrylhydrazyl (DPPH) and 2,2′-azino-bis(3-ethylbenzthiazoline-6-sulfonic acid (ABTS) assays. Additionally, their cytotoxic activity was tested in vitro in a panel of three different cancer (breast, lung and colon) and two normal cell lines. Each selenourea entity contains a para-substituted phenyl ring with different electron-withdrawing and electron-donating groups, and different aliphatic and aromatic nuclei. All of the synthesized selenoureas present antioxidant capacity at high concentrations in the DPPH assay, and three of them (2b, 2c and 2d) showed greater radical scavenging capacity than ascorbic acid at lower concentrations. These results were confirmed by the ABTS assay, where these novel selenoureas present even higher antioxidant capacity than the reference compound Trolox. On the other hand, 10 selenoureas present IC₅₀ values below 10 µM in at least one cancer cell line, resulting in the adamantyl nucleus (6a–6e), the most interesting in terms of activity and selectivity. Outstanding results were found for selenourea 6c, tested in the NCI60 cell line panel and showing an average GI₅₀ of 1.49 µM for the 60 cell lines, and LC₅₀ values ranging from 9.33 µM to 4.27 µM against 10 of these cancer cell lines. To gain insight into its anticancer activity mechanism, we investigated the cell cycle progression of the promising compound 6c, as well as the type of programmed-cell death in a colon cancer cell line it provokes (HT-29). Compound 6c provoked S phase cell cycle arrest and the induction of cell death was independent of caspase activation, suggesting autophagy, though this assertion requires additional studies. Overall, we envision that this compound can be further developed for the potential treatment of colon cancer.

One-Pot Four-Component Assembling for Selenoureas

An efficient and practical method for the straightforward construction of unsymmetrical selenoureas and cycloselenoureas via the combination of selenium powder, chloroform, and two different amines was comprehensively achieved in one-pot with only the assistance of a base under mild conditions. Thirty-three new structures of unsymmetrical selenoureas including three chiral examples and eight cycloselenoureas were achieved. 1,1-Dimethyl-3-phenylselenourea II, which shows good fungicidal activity, was practically synthesized through this protocol in gram-scale. Isoselenocyanate was further confirmed as a key intermediate by control experiment.

Gold as a Possible Alternative to Platinum-Based Chemotherapy for Colon Cancer Treatment

Due to the increasing incidence and high mortality associated with colorectal cancer (CRC), novel therapeutic strategies are urgently needed. Classic chemotherapy against CRC is based on oxaliplatin and other cisplatin analogues; however, platinum-based therapy lacks selectivity to cancer cells and leads to deleterious side effects. In addition, tumor resistance to oxaliplatin is related to chemotherapy failure. Gold(I) derivatives are a promising alternative to platinum complexes, since instead of interacting with DNA, they target proteins overexpressed on tumor cells, thus leading to less side effects than, but a comparable antitumor effect to, platinum derivatives. Moreover, given the huge potential of gold nanoparticles, the role of gold in CRC chemotherapy is not limited to gold(I) complexes. Gold nanoparticles have been found to be able to overcome multidrug resistance along with reduced side effects due to a more efficient uptake of classic drugs. Moreover, the use of gold nanoparticles has enhanced the effect of traditional therapies such as radiotherapy, photothermal therapy, or photodynamic therapy, and has displayed a potential role in diagnosis as a consequence of their optic properties. Herein, we have reviewed the most recent advances in the use of gold(I) derivatives and gold nanoparticles in CRC therapy.

Interplay between Gold(I)-Ligand Bond Components and Hydrogen Bonding: A Combined Experimental/Computational Study

The influence of weak interactions on the donation/back-donation bond components in the complex [(NHC)Au(SeU)]⁺ (NHC = N-heterocyclic carbene; SeU = selenourea) has been studied by coupling experimental and theoretical techniques. In particular, NMR ¹H and pulsed-field gradient spin-echo titrations allowed us to characterize the hydrogen bond (HB) between the -NH₂ moieties of SeU and the anions PF₆ ^- and ClO₄ ^-, whereas ⁷⁷Se NMR spectroscopy allowed us to characterize the Au-Se bond. Theoretically, the Au-Se and Au-C orbital interactions have been decomposed using the natural orbital for the chemical valence framework and the bond components quantified through the charge displacement analysis. This methodology provides the quantification of the Dewar-Chatt-Duncanson (DCD) components for the Au-C and Au-Se bonds in the absence and presence of the second-sphere HB. The results presented here show that the anion has a dual mode action: it modifies the conformation of the cation by ion pairing (and this already influences the DCD components) and it induces new polarization effects that depend on the relative anion/cation relative orientation. The perchlorate polarizes SeU, enhancing the Se → Au σ donation and the Au → C back-donation and depressing the C → Au σ donation. On the contrary, the hexafluorophosphate depresses both the Se → Au and C → Au σ donations.

Cytotoxic effects of gold(i) complexes against colon, cervical and osteo carcinoma cell lines: a mechanistic approach

Water-soluble gold(i) complexes, [Au(Ipr)(L)]PF₆where L = thiourea (Tu)1andN,N′-dimethylthiourea (Me₂Tu)2, were synthesized from the parent 1,3-bis(2,6-di-isopropylphenyl)imidazol-2-ylidenechloridogold(i) [(Ipr)AuCl] (0).