Carbosilane metallodendrimers based on copper (II) complexes: Synthesis, EPR characterization and anticancer activity

Dendritic Pyridine-Imine Copper Complexes as Metallo-Drugs

Since the discovery of cisplatin in the 1960s, the search for metallo-drugs that are more efficient than platinum complexes with negligible side effects has attracted much interest. Among the other metals that have been examined for potential applications as anticancer agents is copper. The interest in copper was recently boosted by the discovery of cuproptosis, a recently evidenced form of cell death mediated by copper. However, copper is also known to induce the proliferation of cancer cells. In view of these contradictory results, there is a need to find the most suitable copper chelators, among which Schiff-based derivatives offer a wide range of possibilities. Gathering several metal complexes in a single, larger entity may provide enhanced properties. Among the nanometric objects suitable for such purpose are dendrimers, precisely engineered hyperbranched macromolecules, which are outstanding candidates for improving therapy and diagnosis. In this review article, we present an overview of the use of a particular Schiff base, namely pyridine-imine, linked to the surface of dendrimers, suitable for complexing copper, and the use of such dendrimer complexes in biology, in particular against cancers.

Combination of Copper Metallodendrimers with Conventional Antitumor Drugs to Combat Cancer in In Vitro Models

Copper carbosilane metallodendrimers containing chloride ligands and nitrate ligands were mixed with commercially available conventional anticancer drugs, doxorubicin, methotrexate and 5-fluorouracil, for a possible therapeutic system. To verify the hypothesis that copper metallodendrimers can form conjugates with anticancer drugs, their complexes were biophysically characterized using zeta potential and zeta size methods. Next, to confirm the existence of a synergetic effect of dendrimers and drugs, in vitro studies were performed. The combination therapy has been applied in two cancer cell lines: MCF-7 (human breast cancer cell line) and HepG2 (human liver carcinoma cell line). The doxorubicin (DOX), methotrexate (MTX) and 5-fluorouracil (5-FU) were more effective against cancer cells when conjugated with copper metallodendrimers. Such combination significantly decreased cancer cell viability when compared to noncomplexed drugs or dendrimers. The incubation of cells with drug/dendrimer complexes resulted in the increase of the reactive oxygen species (ROS) levels and the depolarization of mitochondrial membranes. Copper ions present in the dendrimer structures enhanced the anticancer properties of the whole nanosystem and improved drug effects, inducing both the apoptosis and necrosis of MCF-7 (human breast cancer cell line) and HepG2 (human liver carcinoma cell line) cancer cells.

Design, Synthesis and Activity of New N1-Alkyl Tryptophan Functionalized Dendrimeric Peptides against Glioblastoma

Background: Due to resistance to conventional therapy, a blood–brain barrier that results in poor drug delivery, and a high potential for metastasis, glioblastoma (GBM) presents a great medical challenge. Since the repertoire of the possible therapies is very limited, novel therapeutic strategies require new drugs as well as new approaches. The multiple roles played by L-tryptophan (Trp) in tumorigenesis of GBM and the previously found antiproliferative properties of Trp-bearing dendrimers against this malignancy prompted us to design novel polyfunctional peptide-based dendrimers covalently attached to N¹-alkyl tryptophan (Trp) residues. Their antiproliferative properties against GBM and normal human astrocytes (NHA) and their antioxidant potential were tested. Methods: Two groups of amphiphilic peptide dendrimers terminated with N¹-butyl and N¹-aminopentane tryptophan were designed. The influence of dendrimers on viability of NHA and human GBM cell lines, displaying different genetic backgrounds and tumorigenic potentials, was determined by the MTT test. The influence of compounds on the clonogenic potential of GBM cells was assessed by colony-formation assay. Dendrimers were tested for radical scavenging potency as well as redox capability (DPPH, ABTS, and FRAP models). Results: Several peptide dendrimers functionalized with N¹-alkyl-tryptophan at 5 µM concentration exhibited high selectivity towards GBM cells retaining 85–95% viable NHA cells while killing cancer cells. In both the MTT and colony-formation assays, compounds 21 (functionalized with N¹-butyl-Trp and (+)8 charged) and 25 (functionalized with N¹-aminopentane-Trp and (+)12 charged) showed the most promise for their development into anticancer drugs. According to ABTS, DPPH, and FRAP antioxidant tests, dendrimers functionalized with N¹-alkylated Trp expressed higher ROS-scavenging capacity (ABTS and DPPH) than those with unsubstituted Trp. Conclusions: Peptide dendrimers functionalized with N¹-alkyl-tryptophan showed varying toxicity to NHA, while all were toxic to GBM cells. Based on their activity towards inhibition of GBM viability and relatively mild effect on NHA cells the most advantageous were derivatives 21 and 25 with the respective di-dodecyl and dodecyl residue located at the C-terminus. As expected, peptide dendrimers functionalized with N¹-alkyl-tryptophan expressed higher scavenging potency against ROS than dendrimers with unsubstituted tryptophan.

Amphiphilic Triazine-Phosphorus Metallodendrons Possessing Anti-Cancer Stem Cell Activity

Dendritic molecules bearing metal complexes in their structure (metallodendrimers and metallodendrons) are considered prospective therapeutic entities. In particular, metallodendrons raise interest as antitumor agents for the treatment of poorly curable or drug-resistant tumors. Herein, we have synthesized amphiphilic triazine-phosphorus dendrons bearing multiple copper (II) or gold (III) complexes on the periphery and a branched hydrophobic fragment at the focal point. Due to their amphiphilic nature, metallodendrons formed single micelles (mean diameter ~9 nm) or multi-micellar aggregates (mean diameter ~60 nm) in a water solution. We have tested the antitumor activity of amphiphilic metallodendrons towards glioblastoma, a malignant brain tumor with a notoriously high level of therapy resistance, as a model disease. The metallodendrons exhibit higher cytotoxic activity towards glioblastoma stem cells (BTSC233, JHH520, NCH644, and SF188 cell lines) and U87 glioblastoma cells (IC50 was 3–6 µM for copper-containing dendron and 11–15 µM for gold-containing dendron) in comparison with temozolomide (IC50 >100 µM)—the clinical standard of care for glioblastoma. Our findings show the potential of metallodendron-based nanoformulations as antitumor entities.

Characterization of a fluorescent 1,8-naphthalimide-functionalized PAMAM dendrimer and its Cu(ii) complexes as cytotoxic drugs: EPR and biological studies in myeloid tumor cells

The activity and interacting ability of a polyamidoamine (PAMAM) dendrimer modified with 4-N-methylpiperazine-1,8-naphthalimide units (termed D) and complexed by Cu(ii) ions, towards healthy and cancer cells were studied. Comparative electron paramagnetic resonance (EPR) studies of the Cu(ii)-D complex are presented: coordination mode, chemical structure, flexibility and stability of these complexes, in the absence and presence of myeloid cancer cells and peripheral blood mononuclear cells (PBMC). The interactions of Cu(ii) ions in the biological media at different equilibrium times were studied, highlighting different stability and interacting conditions with the cells. Furthermore, flow cytometry and confocal analysis, trace the peculiar properties of the dendrimers in PBMC and U937 cells. Indeed, a new probe (Fly) was used as a potential fluorescent tool for biological imaging of Cu(ii). The study highlights that dendrimer and, mainly, the Cu(ii) metallodendrimer are cytotoxic agents for the cells, specifically for U937 tumor cells, inducing mitochondrial dysfunction, ROS increase and lysosome involvement. The metallodendrimer shows antitumor selectivity, fewer affecting healthy PBMC, inducing a massive apoptotic cell death on U937 cells, in line with the high stability of this complex, as verified by EPR studies. The results underline the potentiality of this metallodendrimer to be used as anticancer drug.

Peptide Dendrimers with Non-Symmetric Bola Structure Exert Long Term Effect on Glioblastoma and Neuroblastoma Cell Lines

BACKGROUND

Glioblastoma (GBM) is the most common malignant tumor of the central nervous system (CNS). Neuroblastoma (NB) is one of the most common cancers of childhood derived from the neural crest cells. The survival rate for patients with GBM and high-risk NB is poor; therefore, novel therapeutic approaches are needed. Increasing evidence suggests a dual role of redox-active compounds in both tumorigenesis and cancer treatment. Therefore, in this study, polyfunctional peptide-based dendrimeric molecules of the bola structure carrying residues with antiproliferative potential on one side and the antioxidant residues on the other side were designed.

METHODS

We synthesized non-symmetric bola dendrimers and assessed their radical scavenging potency as well as redox capability. The influence of dendrimers on viability of rat primary cerebellar neurons (CGC) and normal human astrocytes (NHA) was determined by propidium iodide staining and cell counting. Cytotoxicity against human GBM cell lines, T98G and LN229, and NB cell line SH-SY5Y was assessed by cell counting and colony forming assay.

RESULTS

Testing of CGC and NHA viability allowed to establish a range of optimal dendrimers structure and concentration for further evaluation of their impact on two human GBM and one human NB cell lines. According to ABTS, DPPH, FRAP, and CUPRAC antioxidant tests, the most toxic for normal cells were dendrimers with high charge and an excess of antioxidant residues (Trp and PABA) on both sides of the bola structure. At 5 μM concentration, most of the tested dendrimers neither reduced rat CGC viability below 50-40%, nor harmed human neurons (NHA). The same dose of compounds 16 or 22, after 30 min treatment decreased the number of SH-SY5Y and LN229 cells, but did not affect the number of T98G cells 48 h post treatment. However, either compound significantly reduced the number of colonies formed by SH-SY5Y, LN229, and T98G cells measured 14 days after treatment.

CONCLUSIONS

Peptide dendrimers with non-symmetric bola structure are excellent scaffolds for design of molecules with pro/antioxidant functionality. Design of molecules with an excess of positive charges and antioxidant residues rendered molecules with high neurotoxicity. Single, 30 min exposition of the GBM and NB cell lines to the selected bola dendrimers significantly suppressed their clonogenic potential.

Elaborated study of Cu(II) carbosilane metallodendrimers bearing substituted iminopyridine moieties as antitumor agents

Iminopyridine-decorated carbosilane metallodendrimers have recently emerged as a promising strategy in the treatment of cancer diseases. Their unique features such as the nanometric size, the multivalent nature and the structural perfection offer an extraordinary platform to explore structure-to-property relationships. Herein, we showcase the outstanding impact on the antitumor activity of a parameter not explored before: the iminopyridine substituents in meta position. New Cu(II) carbosilane metallodendrimers, bearing methyl or methoxy substituents in the pyridine ring, were synthesized and thoroughly characterized. Electron Paramagnetic Resonance (EPR) was exploited to unveil the properties of the metallodendrimers. This study confirmed the presence of different coordination modes of the Cu(II) ion (Cu-N₂O₂, Cu-N₄ and Cu-O₄), whose ratios were determined by the structural features of the dendritic molecules. These metallodendrimers exhibited IC₅₀ values in the low micromolar range (<6 μM) in tumor cell lines such as HeLa and MCF-7. The subsequent in vitro assays on both healthy (PBMC) and tumor (U937) myeloid cells revealed two key facts which improved the cytotoxicity and selectivity of the metallodrug: First, maximizing the Cu-N₂O₂ coordination mode; second, adequately selecting the pair ring-substituent/metal-counterion. The most promising candidates, G₁(-CH₃)Cl (8) and G₁(-OCH₃)NO₃(17), exhibited a substantial increase in the antitumor activity in U937 tumor cells, compared to the non-substituted counterparts, probably through two different ROS-production pathways.

Zinc Complexes with Nitrogen Donor Ligands as Anticancer Agents

The search for anticancer metal-based drugs alternative to platinum derivatives could not exclude zinc derivatives due to the importance of this metal for the correct functioning of the human body. Zinc, the second most abundant trace element in the human body, is one of the most important micro-elements essential for human physiology. Its ubiquity in thousands of proteins and enzymes is related to its chemical features, in particular its lack of redox activity and its ability to support different coordination geometries and to promote fast ligands exchange. Analogously to other trace elements, the impairment of its homeostasis can lead to various diseases and in some cases can be also related to cancer development. However, in addition to its physiological role, zinc can have beneficial therapeutic and preventive effects on infectious diseases and, compared to other metal-based drugs, Zn(II) complexes generally exert lower toxicity and offer few side effects. Zinc derivatives have been proposed as antitumor agents and, among the great number of zinc coordination complexes which have been described so far, this review focuses on the design, synthesis and biological studies of zinc complexes comprising N-donor ligands and that have been reported within the last five years.

Aberrant glycosylation patterns on cancer cells: Therapeutic opportunities for glycodendrimers/metallodendrimers oncology

Despite exciting discoveries and progresses in drug design against cancer, its cure is still rather elusive and remains one of the humanities major challenges in health care. The safety profiles of common small molecule anti-cancer therapeutics are less than at acceptable levels and limiting deleterious side-effects have to be urgently addressed. This is mainly caused by their incapacity to differentiate healthy cells from cancer cells; hence, the use of high dosage becomes necessary. One possible solution to improve the therapeutic windows of anti-cancer agents undoubtedly resides in modern nanotechnology. This review presents a discussion concerning multivalent carbohydrate-protein interactions as this topic pertains to the fundamental aspects that lead glycoscientists to tackle glyconanoparticles. The second section describes the detailed properties of cancer cells and how their aberrant glycan surfaces differ from those of healthy cells. The third section briefly describes the immune systems, both innate and adaptative, because the numerous displays of cell surface protein receptors necessitate to be addressed from the multivalent angles, a strength full characteristic of nanoparticles. The next chapter presents recent advances in glyconanotechnologies, including glycodendrimers in particular, as they apply to glycobiology and carbohydrate-based cancer vaccines. This was followed by an overview of metallodendrimers and how this rapidly evolving field may contribute to our arsenal of therapeutic tools to fight cancer. This article is categorized under: Therapeutic Approaches and Drug Discovery > Emerging Technologies Nanotechnology Approaches to Biology > Nanoscale Systems in Biology Therapeutic Approaches and Drug Discovery > Nanomedicine for Oncologic Disease.

Copper (II) Metallodendrimers Combined with Pro-Apoptotic siRNAs as a Promising Strategy Against Breast Cancer Cells

Cancer treatment with small interfering RNA (siRNA) is one of the most promising new strategies; however, transfection systems that increase its bioavailability and ensure its delivery to the target cell are necessary. Transfection systems may be just vehicular or could contain fragments with anticancer activity that achieves a synergistic effect with siRNA. Cationic carbosilane dendrimers have proved to be powerful tools as non-viral vectors for siRNA in cancer treatment, and their activity might be potentiated by the inclusion of metallic complexes in its dendritic structure. We have herein explored the interaction between Schiff-base carbosilane copper (II) metallodendrimers, and pro-apoptotic siRNAs. The nanocomplexes formed by metallodendrimers and different siRNA have been examined for their zeta potential and size, and by transmission electron microscopy, fluorescence polarisation, circular dichroism, and electrophoresis. The internalisation of dendriplexes has been estimated by flow cytometry and confocal microscopy in a human breast cancer cell line (MCF-7), following the ability of these metallodendrimers to deliver the siRNA into the cell. Finally, in vitro cell viability experiments have indicated effective interactions between Cu (II) dendrimers and pro-apoptotic siRNAs: Mcl-1 and Bcl-2 in breast cancer cells. Combination of the first-generation derivatives with chloride counterions and with siRNA increases the anticancer activity of the dendriplex constructs and makes them a promising non-viral vector.

Synthesis, X-ray structure, antiproliferative activity, interaction with HSA and docking studies of three novel mono and binuclear copper complexes containing the maltol ligand

The present study aims at synthesizing three new copper(ii) complexes of maltol in the presence of 1,10-phenanthroline-, 2,2′-bipyridine- and 4,4-dibromo-2,2′-bipyridine ligands.

Coordination of a triazine ligand with CuII and AgI investigated by spectral, structural, theoretical and docking studies

Two complexes of 5-phenyl-3-(pyridin-2-yl)-1,2,4-triazine (PPTA), namely (ethanol-κO)bis(nitrato-κO)[5-phenyl-3-(pyridin-2-yl-κN)-1,2,4-triazine-κN²]copper(II), [Cu(NO₃)₂(C₁₄H₁₀N₄)(C₂H₆O)] or [Cu(NO₃)₂(PPTA)(EtOH)] (1), and bis[μ-5-phenyl-3-(pyridin-2-yl)-1,2,4-triazine]-κ³N¹:N²,N³;κ³N²,N³:N¹-bis[(nitrato-κO)silver(I)], [Ag₂(NO₃)₂(C₁₄H₁₀N₄)₂] or [Ag₂(NO₃)₂(μ-PPTA)₂] (2), were prepared and characterized by elemental analysis, FT-IR spectroscopy and single-crystal X-ray diffraction. The X-ray structure analysis of 1 revealed a copper complex with square-pyramdial geometry containing two O-donor nitrate ligands along with an N,N'-donor PPTA ligand and one O-donor ethanol ligand. In the binuclear structure of 2, formed by the bridging of two PPTA ligands, each Ag atom has an AgN₃O environment and square-planar geometry. In addition to the four dative interactions, each Ag atom interacts with two O atoms of two nitrate ligands on adjacent complexes to complete a pseudo-octahedral geometry. Density functional theory (DFT) calculations revealed that the geometry around the Cu and Ag atoms in 1^opt and 2^opt (opt is optimized) for an isolated molecule is the same as the experimental results. In 1, O-H...O hydrogen bonds form R₁²(4) motifs. In the crystal network of the complexes, in addition to the hydrogen bonds, there are π-π stacking interactions between the aromatic rings (phenyl, pyridine and triazine) of the ligands on adjacent complexes. The ability of the ligand and complexes 1 and 2 to interact with ten selected biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II and B-DNA) was investigated by docking studies. The results show that the studied compounds can interact with proteins better than doxorubicin (except for TrxR and Top II).

Exploring the Interactions of Ruthenium (II) Carbosilane Metallodendrimers and Precursors with Model Cell Membranes through a Dual Spin-Label Spin-Probe Technique Using EPR

Dendrimers exhibit unique interactions with cell membranes, arising from their nanometric size and high surface area. To a great extent, these interactions define their biological activity and can be reported in situ by spin-labelling techniques. Schiff-base carbosilane ruthenium (II) metallodendrimers are promising antitumor agents with a mechanism of action yet to explore. In order to study their in situ interactions with model cell membranes occurring at a molecular level, namely cetyltrimethylammonium bromide micelles (CTAB) and lecithin liposomes (LEC), electron paramagnetic resonance (EPR) was selected. Both a spin probe, 4-(N,N-dimethyl-N-dodecyl)ammonium-2,2,6,6-tetramethylpiperidine-1-oxyl bromide (CAT12), able to enter the model membranes, and a spin label, 2,2,6,6-tetramethylpiperidine-1-oxyl (TEMPO) covalently attached at newly synthesized heterofunctional dendrimers, were used to provide complementary information on the dendrimer-membrane interactions. The computer-aided EPR analysis demonstrated a good agreement between the results obtained for the spin probe and spin label experiments. Both points of view suggested the partial insertion of the dendrimer surface groups into the surfactant aggregates, mainly CTAB micelles, and the occurrence of both polar and hydrophobic interactions, while dendrimer-LEC interactions involved more polar interactions between surface groups. We found out that subtle changes in the dendrimer structure greatly modified their interacting abilities and, subsequently, their anticancer activity.

Antibacterial Effect of Carbosilane Metallodendrimers in Planktonic Cells of Gram-Positive and Gram-Negative Bacteria and Staphylococcus aureus Biofilm

Antibiotic resistance is currently one of the main threats to public health security. Biofilm formation is a resistance mechanism that is responsible for most human bacterial infections and requires new and effective therapeutic approaches, such as those provided by nanotechnology. In this work, the antibacterial effect of carbosilane metallodendrimers with different metals (copper(II) and ruthenium(II)), ligands (chloride and nitrate) and generations (generation 0, 1 and 2) has been studied using planktonic Gram-positive (Staphylococcus aureus) and Gram-negative (Escherichia coli) bacteria. Furthermore, the ability of the metallodendrimers to avoid the formation of S. aureus biofilms was also evaluated. The results showed a promising biocide activity in both types of planktonic bacteria, especially for first-generation dendrimers, which arises from the metal complexation to the dendrimer. Cu(II) metallodendrimers require lower concentration than Ru(II) counterpart to inhibit the production of S. aureus biofilms, but none produce hemolysis at the inhibitory concentrations and can be safely used as antibacterial agents. In particular, the first-generation Cu(II) metallodendrimer with nitrate ligands displayed the most promising properties to continue with further studies in both planktonic cells and biofilms.

Insight into the antitumor activity of carbosilane Cu(ii)-metallodendrimers through their interaction with biological membrane models

Current cancer therapies present serious drawbacks including severe side-effects and development of drug resistance. Strategies based on nanosized metallodrugs combine the structural diversity and non-classical modes of action of metal complexes with the selectivity arising from the unique interaction of nanoparticles with biological membranes. A new family of water-soluble copper(ii) carbosilane metallodendrimers was synthesized and characterized as a nanotechnological alternative to current therapies. The interactions occurring over time between the dendrimers, at different generations (G₀ to G₂) and with different Cu(ii) counter-ions (nitrate vs. chloride), and cell-membrane models (cethyl-trimethylammonium bromide (CTAB) micelles and lecithin liposomes) were investigated using a computer-aided analysis of the electron paramagnetic resonance (EPR) spectra. The EPR analysis provided structural and dynamical information on the systems indicating that the increase in generation and the change of the Cu(ii) contra-ion - from nitrate to chloride - produce an increased relative amount and strength of interaction of the dendrimer with the model membranes. Interestingly, the stabilization effect produced a lower toxicity towards cancer cells. The cytotoxic effect of Cu(ii) metallodendrimers was verified by an in vitro screening in a selection of tumor cell lines, revealing the impact of multivalency on the effectivity and selectivity of the metallodrugs. As a proof-of-concept, first-generation dendrimer G₁-Cu(ONO₂)₂ was selected for in-depth in vitro and in vivo antitumor evaluation towards resistant prostate cancer. The Cu(ii)-metallodendrimers produced a significant tumor size reduction with no signs of toxicity during the experiment, confirming their promising potential as anticancer metallodrugs.

A novel ligand transfer reaction: Transferring an N3-donor amine ligand from Ni(II) to Cu(II)—structural, spectral, theoretical, and docking studies

Two complexes of N1-(2-aminoethyl)propane-1,3-diamine (AEPD), [Ni(AEPD)2](NO3)2 (1) and [Cu2( μ-Cl)2(AEPD)2](NO3)2·2H2O (2), are prepared and identified by elemental analysis, Fourier transform infrared spectroscopy and UV–Vis spectroscopy, and single-crystal X-ray diffraction (for 2). Spectral and structural data reveal that the AEPD ligand transfers from nickel to copper in the reaction between 1 and copper chloride. All coordination modes of the AEPD-based ligands are studied by analysis of the Cambridge Structural Database. The nickel atom in 1 has octahedral geometry (NiN6) while X-ray structure analysis revealed that the copper atom in the binuclear structure of 2 has an elongated square-pyramidal geometry with a CuN3OCl2 environment. In the crystal network of 2, water molecules and cationic complex units along with the nitrate ions form different hydrogen bond motifs. The thermodynamic stability of the compounds and their charge distribution patterns is studied by density functional theory and natural bond orbital analysis. The ability of AEPD and its complexes to interact with 10 selected biomacromolecules is investigated by docking calculations.

Reaction of 2-[(2-aminoethyl)amino]ethanol with pyridine-2-carbaldehyde and complexation of the products with CuII and CdII along with docking studies

The reaction between 2-[2-(aminoethyl)amino]ethanol and pyridine-2-carbaldehyde in a 1:2 molar ratio affords a mixture containing 2-({2-[(pyridin-2-ylmethylidene)amino]ethyl}amino)ethanol (PMAE) and 2-[2-(pyridin-2-yl)oxazolidin-3-yl]-N-(pyridin-2-ylmethylidene)ethanamine (POPME). Treatment of this mixture with copper(II) chloride or cadmium(II) chloride gave trichlorido[(2-hydroxyethyl)({2-[(pyridin-2-ylmethylidene)amino]ethyl})azanium]copper(II) monohydrate, [Cu(C10H16N3O)Cl3]·H2O or [Cu(HPMAE)Cl3]·H2O, 1, and dichlorido{2-[2-(pyridin-2-yl)oxazolidin-3-yl]-N-(pyridin-2-ylmethylidene)ethanamine}cadmium(II), [CdCl2(C16H18N4O)] or [CdCl2(POPME)], 2, which were characterized by elemental analysis, FT–IR, Raman and 1H NMR spectroscopy and single-crystal X-ray diffraction. PMAE is potentially a tetradentate N3O-donor ligand but coordinates to copper here as an N2 donor. In the structure of 1, the geometry around the Cu atom is distorted square pyramidal. In 2, the Cd atom has a distorted octahedral geometry. In addition to the hydrogen bonds, there are π–π stacking interactions between the pyridine rings in the crystal packing of 1 and 2. The ability of PMAE, POPME and 1 to interact with ten selected biomolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS, Top II and B-DNA) was investigated by docking studies and compared with doxorubicin.

In Vitro Anticancer Properties of Copper Metallodendrimers

Newly synthesized carbosilane copper dendrimers (CCD) with chloride and nitrate surface groups seem to be good candidates to be used as gene and drug carriers in anti-cancer therapy, due to their properties such as size and surface charge. Copper attached to the nanoparticles is an important element of many biological processes and recently their anti-cancer properties have been widely examined. Zeta size and potential, transmission electron microscopy (TEM), circular dichroism (CD), analysis of haemolytic activity, and fluorescence anisotropy techniques were used to characterize copper dendrimers. Additionally, their cytotoxic properties toward normal (PBMC) and cancer (1301; HL-60) cells were examined. All tested dendrimers were more cytotoxic against cancer cells in comparison with normal cells.

Theoretical and experimental investigation of anticancer activities of an acyclic and symmetrical compartmental Schiff base ligand and its Co(ii), Cu(ii) and Zn(ii) complexes

A compartmental Schiff base ligand, 2,2′-((((((2-hydroxypropane-1,3-diyl)bis(oxy))bis(2,1-phenylene))bis(methylene))bis(azanylylidene))bis(methanylylidene))bis(4-bromophenol) (H₃L^Br) and its complexes with cobalt(ii), copper(ii) and zinc(ii) including, [Co(HL^Br)] (1), [Cu₂(L^Br)(μ-1,3-OAc)]·MeOH (2) and [Zn(HL^Br)] (3) were prepared using template synthesis and characterised by elemental analysis, FT-IR and ¹H NMR spectroscopies and single-crystal X-ray diffraction. In the structure of complexes 1 and 3 the metal atom has a MN₂O₂ environment with tetrahedral geometry while complex 2 has a binuclear structure with a MNO₄ environment and square planar geometry around the copper atom. The ability of all compounds to interact with the nine biomacromolecules (BRAF kinase, CatB, DNA gyrase, HDAC7, rHA, RNR, TrxR, TS and Top II) are investigated by docking calculations. For examination of the docking results, the in vitro activities of eight compounds against the human leukemia cell line K562 was investigated by evaluation of IC₅₀ values and mode of cell death (apoptosis).

A compartmental Schiff base ligand and its copper, cobalt and zinc complexes were prepared. The in vitro activities of all compounds against the human leukemia cell line K562 were investigated along with docking and DFT studies.