Cyclopalladated compounds containing 2,6-lutidine: Synthesis, spectral and biological studies

Antitumor activity via apoptotic cell death pathway of water soluble copper(II) complexes: effect of the diamino unit on selectivity against lung cancer NCI-H460 cell line

The cytotoxicity against five human tumor cell lines (THP-1, U937, Molt-4, Colo-205 and NCI-H460) of three water soluble copper(II) coordination compounds containing the ligands 3,3'-(ethane-1,2-diylbis(azanediyl))dipropanamide (BCEN), 3,3'-(piperazine-1,4-diyl)dipropanamide (BPAP) or 3,3'-and (1,4-diazepane-1,4-diyl)dipropanamide (BPAH) are reported in this work. The ligands contain different diamine units (ethylenediamine, piperazine or homopiperazine) and two propanamide units attached to the diamine centers, resulting in N₂O₂ donor sets. The complex containing homopiperazine unit presented the best antiproliferative effect and selectivity against lung cancer cell line NCI-H460, showing inhibitory concentration (IC₅₀) of 58 μmol dm^-3 and Selectivity Index (SI) > 3.4. The mechanism of cell death promoted by the complex was investigated by Sub-G1 cell population analysis and annexin V and propidium iodide (PI) labeling techniques, suggesting that the complex promotes death by apoptosis. Transmission electron microscopy investigations are in agreement with the results presented by mitochondrial membrane potential analysis and also show the impairment of other organelles, including endoplasmic reticulum.

Effect of the hydroxamate group in the antitumoral activity and toxicity toward normal cells of new copper(II) complexes

The synthesis, physico-chemical characterization and cytotoxicity of four copper(II) coordination complexes, i.e. [Cu(HBPA)Cl₂] (1), [Cu(BHA)₂] (2), [Cu(HBPA)(BHA)Cl] CH₃OH (3) and [Cu(HBPA)₂]Cl₂·4H₂O (4), are reported. HBPA is the tridentate ligand N-(2-hydroxybenzyl)-N-(2-pyridylmethyl)amine and HBHA is the benzohydroxamic acid. The reaction between the HBHA and CuCl₂.2H₂O has resulted in the new complex (2) and the reaction between complex (1) and HBHA has resulted in the new complex (3). X-ray diffraction studies for complex (3) indicated the effective coordination of HBHA as BHA^-. Their cytotoxicity was evaluated against three human tumoral cell lines (Colo-205, NCI-H460 and U937) and PBMC (peripheral blood mononuclear cells), using the MTT cytotoxic assay. The results toward PBMC reveal that the new copper(II) complex (2) presents lower toxicity toward normal cells. Furthermore, complex (2) presents IC₅₀ values lower than cisplatin toward NCI-H460 and the best selectivity index obtained towards NCI-H460 (SI = 2.2) and U937 cell lines (SI = 2.0), as a result of the presence of two molecules of HBHA in its structure. Complex (3) presents IC₅₀ values lower than cisplatin toward NCI-H460, Colo-205 and comparable to cisplatin toward U937. The evaluation of the cell death type promoted by complexes (2) and (4) was investigated toward NCI-H460 revealing better results than the standard drug cisplatin, according to the Annexin V and propidium iodide (PI) labeling experiment. Based on the studies here performed, HBHA seems to be related to lower toxicity toward PBMC and HBPA is improving directly the cytotoxity.

In vitro and in silico assessment of antitumor properties and biomolecular binding studies for two new complexes based on NiII bearing k2N,S-donor ligands

This work deals with two new molecule-based materials, namely Ni^II-complexes of general formulae [Ni(L1)₂] (Ni1) and [Ni(L2)₂] (Ni2), where L1 = trans-cinnamaldehyde-N(4)-methyl thiosemicarbazone and L2 = trans-cinnamaldehyde-N(4)-ethyl thiosemicarbazone, as potential antitumor agents. Both compounds were characterized by elemental analysis, molar conductivity and spectroscopic techniques (FTIR and NMR). Their molecular structures were obtained by single-crystal X-ray diffraction analysis. Each one crystallizes in a monoclinic space group P 2₁/c, also the asymmetric unit comprises of one Ni^II ion located on an inversion centre and one anionic ligand, which acts as a κ²N,S-donor affording a five-membered metallaring. The compounds were screened against two selected tumour cell lines (MCF-7 and A549) and non-tumour fibroblasts cell line (MRC-5) via MTT assays. In both tumour cells, all compounds exhibited higher cytotoxicity than the control drug (cisplatin). The IC₅₀ values ranges of 3.70 - 41.37 μM and 1.06 - 14.91 μM were found for MCF-7 and A549, respectively. Importantly, all of them were less toxicity than cisplatin in MRC-5 with SI values ranged at 11.80 - 86.60. The red blood cell (RBC) assay revealed Ni2 as non-toxic due to its reduced haemolytic effect (0--9% at 1--10 μM). The DNA binding was investigated through a combination of spectrophotometric absorption and emission titrations, electrophoresis, and circular dichroism experiments. As a result, these metal complexes were not able to strongly binding to DNA (K_b values ~10⁴ mol L^--1) but suggesting groove-binding interactions. The scavenging ability of them towards 2,2-diphenyl-1-picrylhydrazyl (DPPH) free-radical was also evaluated in this work, but no important antioxidant behaviour was detected. Further, the interaction of Ni1 and Ni2 to human serum albumin (HSA) was explored by quenching of tryptophan emission, warfarin competitive assay, and molecular docking protocols. The HSA binding analyses indicated good affinity of both complexes to Sudlow site I (K_b values ⁓10³ mol L^-1).

Silver(I) complexes of 3-methoxy-4-hydroxybenzaldehyde thiosemicarbazones and triphenylphosphine: structural, cytotoxicity, and apoptotic studies

Novel silver(i) complexes of the type [AgCl(PPh3)2(L)] {PPh3 = triphenylphosphine; L = VTSC = 3-methoxy-4-hydroxybenzaldehyde thiosemicarbazone (1); VMTSC = 3-methoxy-4-[2-(morpholine-1-yl)ethoxy]benzaldehyde thiosemicarbazone (2); VPTSC = 3-methoxy-4-[2-(piperidine-1-yl)ethoxy]benzaldehyde thiosemicarbazone (3)} were synthesized and fully characterized by spectroscopic techniques. The molecular structures of complexes 2 and 3 were determined by single crystal X-ray diffraction. Compounds 1-3 exhibited appreciable cytotoxic activity against human tumor cells (lung A549, breast MDA-MB-231 and MCF-7) with IC50 values in 48 h of incubation ranging from 5.6 to 18 μM. Cellular uptake studies showed that complexes 1-3 were efficiently internalized after 3 hours of treatment in MDA-MB-231 cells. The effects of complex 1 on the cell morphology, cell cycle, induction of apoptosis, mitochondrial membrane potential (Δψm), and reactive oxygen species (ROS) production have been evaluated in triple negative breast cancer (TNBC) cells MDA-MB-231. Our results showed that complex 1 induced typical morphological alterations of cell death, an increase in cells at the sub-G1 phase, apoptosis, and mitochondrial membrane depolarization. Furthermore, DNA binding studies evidenced that 1 can bind to ct-DNA and does so without modifying the B-structure of the DNA, but that the binding is weak compared to that of Hoechst 33258.

Synthesis and Structure of Multinuclear Pd(II) Complexes Bridged by Phosphide or Azide Ligands

The synthesis and structure of phosphide- and azide-bridged multinuclear Pd(II) complexes bearing phosphine ligands [PdX(μ-X')(PR₃)] _n (X = Cl and N₃; X' = PR₂ ^' and N₃; n = 2 and 4) are reported. The oxidative addition of R₂ ^'PCl to Pd(PMe₃)₂ furnished the phosphide-bridged dinuclear Pd(II) complexes [PdCl(μ-PR₂ ^')(PMe₃)]₂ [R' = ⁱ Pr (1a) and Cy (1b)]. However, the oxidative addition of (o-tolyl)₂PCl to Pd(PMe₃)₂ produced a nonbridged mononuclear Pd(II) complex with the bis(o-tolyl)phosphinic ligand, trans-[Pd(PMe₃)₂{P(O)(o-tolyl)₂}] (2), via oxidation of the phosphinyl ligand. The reaction of the chloride-bridged dinuclear Pd(II) complexes [PdCl(μ-Cl)(PR₃)]₂ [PR₃ = PEt₃ (3a) and PPhMe₂ (3b)] with NaN₃ afforded the azide-bridged dinuclear and tetranuclear Pd(II) complexes [Pd(N₃)(μ-N₃)(PEt₃)]₂ (4) and [Pd(N₃)(μ-N₃)(PPhMe₂)]₄ (5). Comparisons of the X-ray structures of 4 and 5 show that the square-planar molecular geometry of the Pd(II) centers of 4 are more distorted than those of 5. Density functional theory calculations suggest that the tetranuclear eight-membered ring structure like 5 is more stable than the dinuclear four-membered ring structure like 4 in the gas phase in both PEt₃ and PPhMe₂ systems. However, because the relative energy difference between the four-membered and eight-membered ring structures is small in the PEt₃ system with smaller steric hindrance compared with PPhMe₂, it is assumed that this difference is compensated by the crystal packing energy, and the dinuclear four-membered ring complex 4 is actually obtained.

Palladium(ii) complexes bearing 1-iminothiolate-3,5-dimethylpyrazoles: synthesis, cytotoxicity, DNA binding and enzymatic inhibition studies

This work describes the enzymatic inhibitory activity of four novel Pd(ii) complexes towards topoisomerase IIα and cathepsins B and L.In silicostudies agree well with the enhancedin vitrocathepsin B inhibition induced by compound4(58% at 10 μM).