α-N-heterocyclic thiosemicarbazone Fe(III) complex: Characterization of its antitumor activity and identification of anticancer mechanism

Synthesis, anticancer activity and mechanism of action of Fe(III) complexes

To inhibit the growth and metastasis of triple-negative breast cancer (TNBC), two Fe(III) thiosemicarbazone complexes (Fe1 and Fe2) were designed and synthesized. The structures of the Fe(III) complexes were characterized by single crystal X-ray diffraction. The antiproliferative activity of Fe1 and Fe2 against four cancer lines (MDA-MB-231, T98G, HepG2, 143B) and human renal proximal tubular epithelial cell line (HK-2) was evaluated by MTT assay. Among all cells, Fe2 showed significant cytotoxicity to TNBC cells (MDA-MB-231), with an IC50 value of 12.38 μM. Furthermore, Fe2 showed less toxicity to HK-2 cells. The two Fe(III) complexes can produce excess of reactive oxygen species, decrease of mitochondrial membrane potential, and induce DNA damage, then lead to apoptosis of MDA-MB-231 cells. In addition, Fe1 and Fe2 can also inhibit migration and invasion of MDA-MB-231 cells. This study provides guidance for the development of metal complexes that inhibit the growth and metastasis of TNBC.

Mixed-ligand copper(ii)-diimine complexes of 3-formylchromone-N 4-phenyl thiosemicarbazone: 5,6-dmp co-ligand confers enhanced cytotoxicity

The promising biological applications of thiosemicarbazone derivatives have inspired the design, synthesis, and study of their Cu(ii) complexes for anticancer therapeutic applications. Herein, we have evaluated the DNA/protein binding, DNA cleaving, and cytotoxic properties of four mixed-ligand Cu(ii) complexes of the type [Cu(L)(diimine)](NO3) 1-4, where HL is 4-oxo-4H-chromene-3-carbaldehyde-4(N)-phenylthiosemicarbazone and diimine is 2,2'-bipyridine (bpy, 1) 1,10-phenanthroline (phen, 2), 5,6-dimethyl-1,10-phenanthroline (5,6-dmp, 3), or dipyrido-[3,2-f:2',3'-h]-quinoxaline (dpq, 4). Interestingly, complex 3 with higher lipophilicity shows stronger DNA binding and oxidative DNA cleavage, higher ROS production, and more reversible redox behaviour, resulting in its remarkable cytotoxicity (IC50, 1.26 μM) against HeLa cervical cancer cells, and rendering it 5 times more potent than the widely used drug cisplatin. The same complex induces enhanced apoptotic cell death on HeLa cells but lower toxicity towards the non-cancerous PBMC cells. Molecular docking studies suggest that all the complexes bind in the minor groove of DNA and subdomain II of HSA, which is in close agreement with the experimental results. Also, 3 shows cytotoxicity higher than the analogous mixed ligand Cu(ii) complexes, reported already, emphasizing the importance of co-ligand in tuning the anticancer activity.

The Effect of ZnO Nanoparticles Functionalized with Glutamine and Conjugated with Thiosemicarbazide on Triggering of Apoptosis in the Adenocarcinoma Gastric Cell Line

Background

Gastric carcinoma is the fourth most common malignancy worldwide. Conjugation of metal nanoparticles with thiosemicarbazones has shown considerable anti-cancer potential.

Materials and Methods

Zinc oxide nanoparticles (ZnO NPs) were synthesized, functionalized by glutamine, and conjugated with thiosemicarbazide (ZnO@Gln-TSC). Fourier transform infrared spectroscopy, X-ray diffraction, scanning electron microscopy and transmission electron microscopy imaging, energy-dispersive X-ray, DLS, and zeta potential were used to characterize the NPs. The toxicity of ZnO NPs, TSC, ZnO@Gln-TSC NPs, and oxaliplatin in AGS cells and ZnO NPs and ZnO@Gln-TSC NPs in HEK293 cells was investigated by MTT assay. Cell apoptosis was evaluated by flow cytometry, caspase-3 activity, and Hoechst staining assays. The intra-cellular reactive oxygen species level and expression level of the CASP3 gene in AGS cells treated with ZnO@Gln-TSC NPs were evaluated.

Results

The NPs were in the size range of 20 to 70 nm. The DLS and zeta potential were 374 nm and -31.7 mV, respectively. In MTT, the IC50 of ZnO, TSC, oxaliplatin, and ZnO@Gln-TSC NPs for AGS cells were 130, 80.5, 67.7, and 9.8 μg/mL, respectively, and the IC50 of ZnO and ZnO@Gln-TSC NPs for HEK293 cells were 215 and 150.5 μg/mL, respectively. Flow cytometry showed higher apoptosis in the cell treated with the NPs and TSC. Apoptotic features, including cell shrinkage, were recognized. A significant increase of 5.9 folds in the level of ROS was noticed. The activity of caspase-3 and the expression level of the CASP3 gene were increased by1.83 and 1.6 folds after exposure to ZnO@Gln-TSC NPs, respectively.

Conclusions

This study revealed the anti-cancer potential of ZnO@Gln-TSC NPs to be used for gastric cancer treatment after further in vitro and in vivo assays.

In Vitro and In Silico Studies on 4-Nitroacetophenone Thiosemicarbazone Potential Cytotoxicity Against A549 Cell Lines

Lung malignancy is a major worldwide issue that occurs due to the dysregulation of various growth factors. Lung cancer has no apparent signs in the early stages, which makes it harder to catch it in time and leads to a higher fatality rate. So, the goal of this work was to create and analyze a novel chemical molecule called 4-nitro acetophenone thiosemicarbazone (4-NAPTSc) against the lung cancer cell line A549 and human non-tumorigenic lung epithelial cell line BAES-2B. The ligand was synthesized by refluxing the reaction mixture of 4-nitro acetophenone and thiosemicarbazide and was further characterized by UV, FTIR, and 1H and 13C NMR and Differential Scanning Calorimetry (DSC) study. Cytotoxicity assay/MTT (3-(4,5-dimethylthiazol-2-yl))2,5-diphenyltetrazolium bromide) was used to evaluate the cytotoxicity of the compound. Epidermal growth factor receptors (EGFR), polo-like kinase-1 (PLK1), and vascular endothelial growth factor receptors (VEGFR) were chosen as the target proteins for molecular docking to find potential ligand binding sites and inhibit their function. A novel yellow-colored crystalline solid has been synthesized. 4-NAPTSc had an IC50 of 2.93 μg/mL against the A549 lung cancer cells. When the dosage is increased from 5 to 15 μg/mL along with time, the cell viability falls. Docking results showed that the compound binds with the targeted proteins' amino acid residues, and the likeness profile of the compound is also favorable. This study reveals that the compound has the potential for further investigation and can be used in multitargeted cancer therapies.

Recent progress in thiocarbazone metal complexes for cancer therapy via mitochondrial signalling pathway

Mitochondria are the energy factories of cells and are important targets for the development of novel tumour treatment strategies owing to their involvement in processes such as apoptosis, oxidative stress, and metabolic programming. Thiosemicarbazone metal complexes target mitochondria and reduce mitochondrial membrane potential. The breakdown of mitochondrial membrane potential is a key event in the early stage of apoptosis, which releases cytochrome C and other pro-apoptotic factors, activates the intracellular apoptotic enzyme cascade, and eventually causes irreversible apoptosis of tumour cells. Thiosemicarbazone metal complexes targeting the mitochondria have recently emerged as potential antitumour agents; therefore, this review describes the structural diversity of thiosemicarbazone metal [Fe(III), Cu(II), Ni(II), Zn(II), Ga(III), Pb(II), Au(III), and Ir(III)] complexes and explores their anti-tumour mechanisms that target mitochondrial pathways.

Role of the auxiliary ligand in determining the genotoxicity and mode of cell death of thiosemicarbazone Pd(II) complexes

A series of Pd(II) complexes of the general formula [PdX(NNS)] (X = Cl, Br, I, NCS and phenyl-tetrazole-thiolato; NNS = 2-quinolinecarboxyaldehyde-N4-phenylthiosemicarbazone) was tested against four malignant cell lines for their antiproliferative properties and the outcomes were compared to those seen in normal mouse splenocytes. Various auxiliary ligands were substituted in order to investigate the impact of the character of the ligand on the cytotoxicity of this class of Pd(II) complexes. The iodo complex was the most cytotoxic compound towards the Caco-2 cell line in this study. The improved apoptosis and necrosis cell modes were in accordance with the fragmentation results of DNA, which revealed increased fragmentation terminals, especially in isothiocyanate and tetrazole-thiolato complexes. After 24 hours, at half the IC50 of each complex, the complex-treated cells exhibited considerable genotoxicity when compared to the corresponding non-treated control especially in the case of isothiocyanate and tetrazole-thiolato complexes.

New Stable Gallium(III) and Indium(III) Complexes with Thiosemicarbazone Ligands: A Biological Evaluation

The aim of this work is to explore a new library of coordination compounds for medicinal applications. Gallium is known for its various applications in this field. Presently, indium is not particularly important in medicine, but it shares a lot of chemical traits with its above-mentioned lighter companion, gallium, and is also used in radio imaging. These metals are combined with thiosemicarbazones, ligating compounds increasingly known for their biological and pharmaceutical applications. In particular, the few ligands chosen to interact with these hard metal ions share the ideal affinity for a high charge density. Therefore, in this work we describe the synthesis and the characterization of the resulting coordination compounds. The yields of the reactions vary from a minimum of 21% to a maximum of 82%, using a fast and easy procedure. Nuclear Magnetic Resonance (NMR) and Infra Red (IR) spectroscopy, mass spectrometry, elemental analysis, and X-ray Diffraction (XRD) confirm the formation of stable compounds in all cases and a ligand-to-metal 2:1 stoichiometry with both cations. In addition, we further investigated their chemical and biological characteristics, via UV-visible titrations, stability tests, and cytotoxicity and antibiotic assays. The results confirm a strong stability in all explored conditions, which suggests that these compounds are more suitable for radio imaging applications rather than for antitumoral or antimicrobic ones.

Exploring Synthesis and Chemotherapeutic Potential of Thiosemicarbazide Analogs

BACKGROUND

Cancer is a leading cause of death worldwide, accounting for nearly 10 million deaths in 2020. Researchers are continually finding new and more effective medications to battle the diseases.

OBJECTIVE

The objective of this study is to identify the emerging role of Thiosemicarbazide analogs for different types of cancer targets with a glance at different novel synthetic routes reported for their synthesis.

METHODS

A systematic literature review was conducted from various sources over the last 15 years with the inclusion of published research and review articles that involves the synthesis and use of thiosemicarbazide analogs for different targets of cancer. Data from the literature review for synthesis and anticancer potential for specific targets for cancer studies of thiosemicarbazide analogs are summarized in the paper.

RESULTS

There are several emerging studies for new synthetic routes of thiosemicarbazide derivatives with their role in various types of cancers. The main limitation is the lack of clinical trial of the key findings for the emergence of new anticancer medication with thiosemicarbazide moiety.

CONCLUSION

Emerging therapies exist for use of a limited number of medications for the treatment of cancer; results of the ongoing studies will provide more robust evidence in the future.

Iron Oxide Nanoparticles Conjugated to Thiosemicarbazone Reduce the Survival of Cancer Cells by Increasing the Gene Expression of MicroRNA let-7c in Lung Cancer A549 Cells

BACKGROUND

Cancer cells have a higher demand for iron to grow and proliferate. A new complex of iron nanoparticles and thiosemicarbazones was synthesized. Confirmation tests included UV-visible, scanning electron microscopy (SEM), energy dispersive X-ray analysis (EDX), Fourier transform infrared (FTIR), X-ray diffraction (XRD) and zeta potential.

METHODS

MTT assay, flow cytometry and qRT-PCR were used to investigate anti-proliferative effect, amount of apoptosis and the effect of Fe3 O4 @Glu/BTSC on changes in gene expression of microRNA let-7c (let-7c), respectively. The specifications of Fe3 O4 @ Glu/BTSC were confirmed at 5 nm.

RESULTS

Fe3O4@Glu/BTSC was more effective than BTSC and Fe3 O4 on A549 cells (IC50=166.77 µg/mL) but its effect on healthy cells was smaller (CC50=189.15 µg/mL). The drug selectivity index (SI) was calculated to be 1.13. The initial apoptosis rate was 46.33% for Fe3 O4 @Glu/BTSC, 28.27% for BTSC and 26.02% for Fe3 O4 . BTSC and BTSC@Fe3 O4 inhibited the cell cycle progression in the Sub-G1 and S phases. let-7c expression was 6.9 times higher in treated cells compared to the control group. The expression rate was 2.2 with BTSC compared to the control group and 1.6 times for Fe3 O4.

CONCLUSION

Fe3 O4 @Glu/BTSC has proper anti-proliferative effects against lung cancer cells by increasing the expression of let-7c and inhibiting the cell cycle with the apoptosis activation pathway.

Bis-pharmacophore of cinnamaldehyde-clubbed thiosemicarbazones as potent carbonic anhydrase-II inhibitors

Here, we report the synthesis, carbonic anhydrase-II (CA-II) inhibition and structure–activity relationship studies of cinnamaldehyde-clubbed thiosemicarbazones derivatives. The derivatives showed potent activities in the range of 10.3 ± 0.62–46.6 ± 0.62 µM. Among all the synthesized derivatives, compound 3n (IC₅₀ = 10.3 ± 0.62 µM), 3g (IC₅₀ = 12.1 ± 1.01 µM), and 3h (IC₅₀ = 13.4 ± 0.52 µM) showed higher inhibitory activity as compared to the standard inhibitor, acetazolamide. Furthermore, molecular docking of all the active compounds was carried out to predict their behavior of molecular binding. The docking results indicate that the most active hit (3n) specifically mediate ionic interaction with the Zn ion in the active site of CA-II. Furthermore, the The199 and Thr200 support the binding of thiosemicarbazide moiety of 3n, while Gln 92 supports the interactions of all the compounds by hydrogen bonding. In addition to Gln92, few other residues including Asn62, Asn67, The199, and Thr200 play important role in the stabilization of these molecules in the active site by specifically providing H-bonds to the thiosemicarbazide moiety of compounds. The docking score of active hits are found in range of − 6.75 to − 4.42 kcal/mol, which indicates that the computational prediction correlates well with the in vitro results.

Spectroscopy, Structure, Biomacromolecular Interactions, and Antiproliferation Activity of a Fe(II) Complex With DPA-Bpy as Pentadentate Ligand

An Fe(II) complex with DPA-Bpy (DPA-Bpy = N,N-bis(2-pyridinylmethyl)-2,20-bipyridine-6 -methanamine) as the ligand was synthesized and characterized to mimic bleomycin. The binding constants (K_b) of the complex with calf thymus DNA and human serum albumin (HSA) were quantitatively evaluated using fluorescence spectroscopy, with K_b as 5.53×10⁵ and 2.40×10⁴ M⁻¹, respectively; the number of the average binding site (n) is close to 1. The thermodynamic analyses suggested that the electrostatic interactions exist between the complex and DNA, and the hydrogen bonding and Van der Waals force exist for the complex and HSA. The Fe complex exhibits cleavage ability toward pBR322 DNA, and the crystal structure of the HSA Fe complex adduct at 2.4 Å resolution clearly shows that His288 serves as the axial ligand of the Fe center complexed with a pentadentate DPA-Bpy ligand. Furthermore, the cytotoxicity of the complex was evaluated against HeLa cells. Both the Fe complex and HSA Fe complex adduct show obvious effect on cell proliferation with an IC₅₀ of 1.18 and 0.82 μM, respectively; they induced cell apoptosis and arrested cell cycles at S phase. This study provides insight into the plausible mechanism underlying their metabolism and pharmacological activity.

Dithiocarbazate-FeIII, -CoIII, -NiII, and -ZnII Complexes: Design, Synthesis, Structure, and Anticancer Evaluation

Non-platinum-metal complexes show great potential as anticancer agents. Herein, a series of dithiocarbazate non-Pt-metal complexes, including [Fe^III(L)₂]·Cl·2H₂O 1, [Co^III(L)₂]·NO₃·2.5H₂O 2, [Ni^II(L)₂] 3, and [Zn^II(L)₂] 4, have been designed and evaluated for their efficacy as antineoplastic agents. Among them, complex 2 exhibited higher anticancer efficacy than complexes 1, 3, 4, and cisplatin against several cancer cell lines. Hemolysis assays revealed that complex 2 showed comparable hemolysis with cisplatin. In vivo anticancer evaluations showed that complex 2 could retard tumor xenograft growth effectively with low systemic toxicity. Further studies revealed that complex 2 suppressed cancer cells by triggering multiple mechanisms involving the simultaneous inhibition of mitochondria and glycolytic bioenergetics. Overall, our study provides new insights into the anticancer mechanism of Co complexes, which can be used as a good strategy to overcome the flexibility of cancer cells to chemotherapy adaptation.

Crystal structures of 3/4-pyridyl-based thiosemicarbazones and related Cu and Ni coordination compounds

In this investigation, the crystal structures of the thio-ligands 3-formylpyridine 4-phenylthiosemicarbazone (C₁₃H₁₂N₄S, 1) and 4-benzoylpyridine 4-ethylthiosemicarbazone (C₁₅H₁₆N₄S, 2), and of two new coordination compounds, chlorido(3-formylpyridine 4-phenylthiosemicarbazone-κS)bis(triphenylphosphane-κP)copper(I) acetonitrile monosolvate, [CuCl(C₁₃H₁₂N₄S)(C₁₈H₁₅P)₂]·CH₃CN, 3, and bis(3-formylpyridine 4-ethylthiosemicarbazonato-κ²N¹,S)nickel(II), [Ni(C₉H₁₁N₄S)₂], 4, are reported. In complex 3, the thio-ligand coordinates in a neutral form to the Cu atom through its S-donor atom, and in complex 4, the anionic thio-ligand chelates to the Ni atom through N- and S-donor atoms. The geometry of complex 3 is distorted tetrahedral [bond angles 99.70 (5)-123.23 (5)°], with the P-Cu-P bond angle being the largest, while that of complex 4 is square planar, with trans-S-Ni-S and N-Ni-N bond angles of 180°.

Coordination compounds of biogenic metals as cytotoxic agents in cancer therapy

The review summarizes the data on the structures and methods for the synthesis of compounds with anticancer activity based on biogenic metals, which can replace platinum drugs prevailing in cytotoxic therapy. The main focus is given to the comparison of the mechanisms of the cytotoxic action of these complexes, their efficacy and prospects of their use in clinical practice. This is the first systematic review of cytotoxic zinc, iron, cobalt and copper compounds. The structure – activity relationships and the mechanisms of antitumour action are formulated for each type of metal complexes.

The bibliography includes 181 references.

Synthesis and antioxidant activities of new nickel(II) complexes derived from 4-benzyloxysalicylidene-S-methyl/propyl thiosemicarbazones

Six nickel(II) complexes of the N₂O₂ chelating thiosemicarbazones were synthesized using N¹-4-benzyloxysalicylidene-S-methyl/propyl thiosemicarbazone and methoxy-substitute-salicylaldehydes in the presence of Ni(II) ion by template reaction. The structures of thiosemicarbazones and nickel(II) complexes were characterized by elemental analysis, UV-Vis, IR, and ¹H-NMR spectroscopies. The structure of the N¹-4-benzyloxysalicylidene-S-propyl thiosemicarbazone ( 2 ) was determined by X-ray single-crystal diffraction method. The total antioxidant capacities of synthesized compounds were evaluated by using cupric reducing antioxidant capacity (CUPRAC) method. The thiosemicarbazones exhibited more potent antioxidant capacity than Ni(II) complexes. Trolox equivalent antioxidant capacity (TEAC) of 1c was found highest in tested nickel(II) complexes. In addition, antioxidant activities of tested compounds were evaluated by using the hydroxyl radical, DPPH radical, and ABTS radical scavenging abilities of these compounds.

Antitumor activity of tridentate pincer and related metal complexes

Pincer complexes featuring tunable tridentate ligand frameworks are one of the most actively studied classes of metal-based complexes. Currently, growing attention is devoted to the cytotoxicity of pincer and related metal complexes. The antiproliferative activity of numerous pincer complexes has been reported. Pincer tridentate ligand scaffolds show different coordination modes and offer multiple options for directed structural modifications. This review summarizes the significant progress in the research studies of the antitumor activity of pincer and related platinum(ii), gold(iii), palladium(ii), copper(ii), iron(iii), ruthenium(ii), nickel(ii) and some other metal complexes, in order to provide a reference for designing novel metal coordination drug candidates with promising antitumor activity.

Syntheses, crystal structures of two Fe(III) Schiff base complexes with chelating o-vanillin aroylhydrazone and exploration of their bio-relevant activities

Two novel Fe(III) complexes, Fe(HL¹)₂Cl·1.25H₂O (1) and Fe(HL²)₂·Et₃NH·H₂O (2) (H₂L¹ = o-vanillin benzoylhydrazone, H₃L² = o-vanillin salicylhydrazone) are prepared. X-ray single crystal diffraction confirms that the hydrazone ligands can be chelated to iron centre resulting in a six-coordinate octahedral configuration. Both complexes show major intercalation effect to the herring sperm deoxyribonucleic acid (HS-DNA) with high binding constants of 2.01 × 10⁴ M^-1 and 2.24 × 10⁴ M^-1, respectively. Molecular docking studies reveal both complexes can intercalate at the gap of DC5-DG2 and DG6-DC1 base pairs of DNA hexamer (1Z3F). The interaction of the complex 1 with plasmid pBR322 DNA induces distinguishable alterations of the DNA morphology. Further, the structure of plasmid pBR322 DNA treated with complex 1 in the presence of ascorbic acid has been damaged probably due to the reactive oxygen species (ROS) generation. What's more, both complexes show high affinity with bovine serum albumin (BSA), the binding constants measured by fluorescence techniques are 5.75 × 10⁶ M^-1 and 4.39 × 10⁷ M^-1, respectively. Molecular docking demonstrates that the complexes prefer the binding pocket of site III (subdomain IIB) of BSA (PDB ID: 4F5S). Similarly, dynamic light scattering (DLS) reveals that the complexes not only bind to BSA but also induce bigger size aggregates as the concentration increases.

Dual-target platinum(IV) complexes exhibit antiproliferative activity through DNA damage and induce ER-stress-mediated apoptosis in A549 cells

Platinum(II)-based chemotherapeutics are commonly used to treat various types of solid tumors, such as lung cancers. However, these compounds can cause serious side effects, including nephrotoxicity and ototoxicity, which affect the quality of life of patients. In our work, four novel dual target platinum(IV) complexes were designed and synthesized. In vitro results indicated that the title platinum(IV) complexes exhibited effective antitumor activities against the tested cancer cells and had lower toxicity and resistance factors than oxaliplatin and cisplatin. Further mechanistic experiments demonstrated that complex 11 accumulated in mitochondria and induced an elevation in ROS and an ER stress response via mitochondrial dysfunction. Notably, complex 11 significantly modulated the expression levels of proapoptosis proteins including cleaved-Caspase-3, Bax, and p53, and decreased the level of the prosurvival protein Bcl-2. Together, these results suggested that complex 11 might be a potential lead compound for future cancer therapy due to its potency and selectivity.

S. Paqui M, Amorim AL, P. de Paula C, Rocha MC, Malavazi I, Cunha A, S. Santana F, Ribeiro RR, Gariani RA, Mendes SR, Xavier FR. Polypyridyl iron(iii) complexes containing long alkyl chains: synthesis, characterization, DFT calculations and biological activity

A bis(picolyl)amine ligand was functionalized with a long alkyl chain, and two iron(iii) complexes were prepared and their biological activity was presented.

Synthesis and biological screening of thiosemicarbazones of substituted 3-acetylcoumarins having d-glucose moiety

Thiosemicarbazones 5a-j were synthesized with yields of 45-68% by condensation of 3-acetylcoumarins 3a-j and tetra-O-acetyl-β-d-thiosemicarbazide 4. All obtained thiosemicarbazones were screened for anti-microorganic activities against bacteria (B. subtilis, S. aureus, S. epidermidis, E. coli, P. aeruginosa, K. pneumoniae, S. typhimurium) and fungi (A. niger, C. albicans, S. cerevisiae, and A. flavus). Some compounds had significant inhibitory activity with MICs of 0.78-3.125 μM in comparison with 5a, including 5e,h,i for S. aureus, and 5c,f,i for S. epidermidis (Gram-(+) bacteria), 5c,f,g for E.coli, 5f for K. pneumoniae, 5b,c,g for P. aeruginosa, and 5i for S. typhimurium (Gram-(-) bacteria), 5d,h,i for A. niger, 5i for A. flavus, 5b,d,e,h for C. albicans, and 5i for S. cerevisiae. Compounds exhibited excellent activity against tested microorganism with MIC = 0.78 μM, including 5h,i (against S. aureus), 5h (against C. albicans), and 5i (against S. cerevisiae).

Synthesis, Spectroscopic Characterization, Structural Studies, and In Vitro Antitumor Activities of Pyridine-3-carbaldehyde Thiosemicarbazone Derivatives

Eight new thiosemicarbazone derivatives, 6-(1-trifluoroethoxy)pyridine-3-carbaldehyde thiosemicarbazone (1), 6-(4′-fluorophenyl)pyridine-3-carbaldehyde thiosemicarbazone (2), 5-chloro-pyridine-3-carbaldehyde thiosemicarbazone (3), 2-chloro-5-bromo-pyridine-3-carbaldehyde thiosemicarbazone (4), 6-(3′,4′-dimethoxyphenyl)pyridine-3-carbaldehyde thiosemicarbazone (5), 2-chloro-5-fluor-pyridine-3-carbaldehyde thiosemicarbazone, (6), 5-iodo-pyridine-3-carbaldehyde thiosemicarbazone (7), and 6-(3′,5′-dichlorophenyl)pyridine-3-carbaldehyde thiosemicarbazone (8) were synthesized, from the reaction of the corresponding pyridine-3-carbaldehyde with thiosemicarbazide. The synthesized compounds were characterized by ESI-Mass, UV-Vis, IR, and NMR (1H, 13C, 19F) spectroscopic techniques. Molar mass values and spectroscopic data are consistent with the proposed structural formulas. The molecular structure of 7 has been also confirmed by single crystal X-ray diffraction. In the solid state 7 exists in the E conformation about the N2-N3 bond; 7 also presents the E conformation in solution, as evidenced by 1H NMR spectroscopy. The in vitro antitumor activity of the synthesized compounds was studied on six human tumor cell lines: H460 (lung large cell carcinoma), HuTu80 (duodenum adenocarcinoma), DU145 (prostate carcinoma), MCF-7 (breast adenocarcinoma), M-14 (amelanotic melanoma), and HT-29 (colon adenocarcinoma). Furthermore, toxicity studies in 3T3 normal cells were carried out for the prepared compounds. The results were expressed as IC50 and the selectivity index (SI) was calculated. Biological studies revealed that 1 (IC50 = 3.36 to 21.35 μM) displayed the highest antiproliferative activity, as compared to the other tested thiosemicarbazones (IC50 = 40.00 to >582.26 μM) against different types of human tumor cell lines. 1 was found to be about twice as cytotoxic (SI = 1.82) than 5-fluorouracile (5-FU) against the M14 cell line, indicating its efficiency in inhibiting the cell growth even at low concentrations. A slightly less efficient activity was shown by 1 towards the HuTu80 and MCF7 tumor cell lines, as compared to that of 5-FU. Therefore, 1 can be considered as a promising candidate to be used as a pharmacological agent, since it presents significant activity and was found to be more innocuous than the 5-FU anticancer drug against the 3T3 mouse embryo fibroblast cells.

Synthesis, bioactivity and binding energy calculations of novel 3-ethoxysalicylaldehyde based thiosemicarbazone derivatives

In recent decade, the entrance of α-N-heterocyclic thiosemicarbazones derivates (Triapne, COTI-2 and DpC) in clinical trials for cancer and HIV-1 has vastly increased the interests of medicinal chemists towards this class of organic compounds. In the given study, a series of eighteen new (3a-r) 3-ethoxy salicylaldehyde-based thiosemicarbazones (TSC), bearing aryl and cycloalkyl substituents, were synthesized and assayed for their pharmacological potential against carbonic anhydrases (hCA I and hCA II), cholinesterases (AChE and BChE) and α-glycosidase. The hCA I isoform was inhibited by these novel 3-ethoxysalicylaldehyde thiosemicarbazone derivatives (3a-r) in low nanomolar levels, the Ki of which differed between 144.18 ± 26.74 and 454.92 ± 48.32 nM. Against the physiologically dominant isoform hCA II, the novel compounds demonstrated K_is varying from 110.54 ± 14.05 to 444.12 ± 36.08 nM. Also, these novel derivatives (3a-r) effectively inhibited AChE, with Ki values in the range of 385.38 ± 45.03 to 983.04 ± 104.64 nM. For BChE was obtained with Ki values in the range of 400.21 ± 35.68 to 1003.02 ± 154.27 nM. For α-glycosidase the most effective Ki values of 3l, 3n, and 3q were with Ki values of 12.85 ± 1.05, 16.03 ± 2.84, and 19.16 ± 2.66 nM, respectively. Moreover, the synthesized TCSs were simulated using force field methods whereas the binding energies of the selected compounds were estimated using MM-GBSA method. The findings indicate the present novel 3-ethoxy salicylaldehyde-based thiosemicarbazones to be excellent hits for pharmaceutical applications.

Guedes da Silva MF, Marzano C. Synthesis, Characterization and Biological Activity of Novel Cu(II) Complexes of 6-Methyl-2-Oxo-1,2-Dihydroquinoline-3-Carbaldehyde-4n-Substituted Thiosemicarbazones

Three new 6-methyl-2-oxo-1,2-dihydroquinoline-3-carbaldehyde-thiosemicarbazones-N-4-substituted pro-ligands and their Cu(II) complexes (1, -NH2; 2, -NHMe; 3, -NHEt) have been prepared and characterized. In both the X-ray structures of 1 and 3, two crystallographically independent complex molecules were found that differ either in the nature of weakly metal-binding species (water in 1a and nitrate in 1b) or in the co-ligand (water in 3a and methanol in 3b). Electron Paramagnetic Resonance (EPR) measurements carried out on complexes 1 and 3 confirmed the presence of such different species in the solution. The electrochemical behavior of the pro-ligands and of the complexes was investigated, as well as their biological activity. Complexes 2 and 3 exhibited a high cytotoxicity against human tumor cells and 3D spheroids derived from solid tumors, related to the high cellular uptake. Complexes 2 and 3 also showed a high selectivity towards cancerous cell lines with respect to non-cancerous cell lines and were able to circumvent cisplatin resistance. Via the Transmission Electron Microscopy (TEM) imaging technique, preliminary insights into the biological activity of copper complexes were obtained.

New ruthenium polypyridyl complexes functionalized with fluorine atom or furan: Synthesis, DNA-binding, cytotoxicity and antitumor mechanism studies

Two novel ruthenium(II) polypyridyl complexes, namely, [Ru(dmp)₂(CAPIP)](ClO₄)₂ (Ru(II)-1) and [Ru(dmp)₂(CFPIP)](ClO₄)₂ (Ru(II)-2), which respectively contain (E)-2-(2-(furan-2-yl)vinyl)-1H-imidazo[4,5-f][1,10]phen-anthroline (CAPIP) and (E)-2-(4-fluorostyryl)-1H-imidazo[4,5-f][1,10]phenanthroline. (CFPIP), were first designed and characterized (dmp = 2,9-dimethyl-1,10-phenanthroline). DNA binding experiments indicated that Ru(II) complexes interact with CT DNA through intercalative mode. In addition, the complexes Ru(II)-1 and Ru(II)-2, showed remarkable cell cytotoxicity, giving the respective IC₅₀ values of 4.1 ± 1.4 μM and 6.1 ± 1.4 μM on the A549 cancer cells. These values indicated higher activity than CAPIP, CFPIP, cisplatin (8.2 ± 1.4 μM) and other corresponding Ru(II) polypyridyl complexes. Furthermore, the Ru(II) complexes could arrive the cytoplasm through the cell membrane and accumulate in the mitochondria. Significantly, complexes Ru(II)-1 and Ru(II)-2 induced A549 cells apoptosis was mediated by increase of ROS levels and dysfunction of mitochondria, and resulted in cell cycle arrest and increased anti-migration activity on A549 cells. Overall, these results indicated that complexes Ru(II)-1 and Ru(II)-2 could be suitable candidates for further investigation as a chemotherapeutic agent in the treatment of tumors.

Thiosemicarbazone-metal complexes exhibiting cytotoxicity in colon cancer cell lines through oxidative stress

Colorectal cancer is the third most common type of cancer and has a high incidence in developed countries. At present, specific treatments are being required to allow individualized therapy depending on the molecular alteration on which the drug may act. The aim of this project is to evaluate whether HPTSC and HPTSC* thiosemicarbazones (HPTSC = pyridine-2-carbaldehyde thiosemicarbazone and HPTSC* = pyridine-2-carbaldehyde 4N-methylthiosemicarbazone), and their complexes with different transition metal ions as Cu(II), Fe(III) and Co(III), have antitumor activity in colon cancer cells (HT-29 and SW-480), that have different oncogenic characteristics. Cytotoxicity was evaluated and the involvement of oxidative stress in its mechanism of action was analyzed by quantifying the superoxide dismutase activity, redox state by quantification of the thioredoxin levels and reduced/oxidized glutathione rate and biomolecules damage. The apoptotic effect was evaluated by measurements of the levels of caspase 9 and 3 and the index of histones. All the metal-thiosemicarbazones have antitumor activity mediated by oxidative stress. The HPTSC*-Cu was the compound that showed the best antitumor and apoptotic characteristics for the cell line SW480, that is KRAS gene mutated.

Synthesis, mechanisms of action, and toxicity of novel aminophosphonates derivatives conjugated irinotecan in vitro and in vivo as potent antitumor agents

Twenty novel aminophosphonates derivatives (5a-5j and 6a-6j) conjugated irinotecan were synthesized through esterification reaction, and evaluated their anticancer activities using MTT assay. In vitro evaluation revealed that they displayed similar or superior cytotoxicity compared to the positive drug irinotecan against A549, MCF-7, SK-OV-3, MG-63, U2OS and multidrug-resistant (MDR) SK-OV-3/CDDP cancer cell lines. Among them, 9b displayed the most potent activity, with IC₅₀ values of 0.92-3.23 μM against five human cancer cells, which exhibited a 5.4-19.1-fold increase in activity compared to the reference drug irinotecan, respectively. Moreover, cellular mechanism studies suggested that 9b arrested cell cycle at S stage and induced cell apoptosis along with the decrease of mitochondrial membrane potential (MMP). Interestingly, 9b significantly inhibited tumor growth in SK-OV-3 xenograft models in vivo without apparent toxicity, which was better than the positive drug irinotecan. Taken together, 9b possessed potent antitumor activity and may be a promising candidate for the potential treatment of human ovarian cancer cells.

Synthesis and spectral characterizations of water soluble Cu(ii) complexes containing N-heterocyclic chelates: cell-proliferation, antioxidant and nucleic acid/serum albumin interactions

Water soluble N-heterocyclic copper(ii) complexes were synthesized, characterized and studied their DNA/protein binding interactions, antioxidation and antiproliferative potentials. The complex 4 found to be better than other complexes.

Novel pyridinecarboxaldehyde thiosemicarbazone conjugated magnetite nanoparticulates (MNPs) promote apoptosis in human lung cancer A549 cells

The present study highlights the apoptotic activity of magnetic Fe₃O₄ nanoparticulates functionalized by glutamic acid and 2-pyridinecarboxaldehyde thiosemicarbazone (PTSC) toward human lung epithelial carcinoma A549 cell line. To this aim, the Fe₃O₄ nanoparticulates were prepared using co-precipitation method. Then, the glutamic acid and Fe₃O₄ nanoparticulates were conjugated to each other. The product was further functionalized with bio-reactive PTSC moiety. In addition, the synthesized Fe₃O₄@Glu/PTSC nanoparticulates were characterized by physico-chemical techniques including scanning electron microscope (SEM), energy dispersive X-ray (EDX), X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectroscopy and zeta potential analysis. The effects of in vitro cell viability in Fe3O4@Glu/PTSC nanoparticulate indicated the anti-proliferative properties in a dose-dependent manner (IC₅₀ = 135.6 µM/mL). The high selectivity for tumor cells and far below of activity in HEK293 non-tumorigenic cells is considered as an important feature for this complex (SI, 3.48). Based on the results, PTSC failed to reveal any activity against A549 cells alone. However, Fe₃O₄ nanoparticulates had some effects in inhibiting the growth of lung cancer cell. Furthermore, Bax and Bcl-2 gene expressions were quantified by real-time PCR method. The expression of Bax increased 1.62-fold, while the expression of Bcl-2 decreased 0.76-fold at 135.6 µM/mL concentration of Fe₃O₄@Glu/PTSC compared to untreated A549 cells. Furthermore, the Fe₃O₄@Glu/PTSC nanoparticulate-inducing apoptosis properties were evaluated by Hoechst 33258 staining, Caspase-3 activation assay and Annexin V/propidium iodide staining. The results of the present study suggest that Fe₃O₄@Glu/PTSC nanoparticulates exhibit effective anti-cancer activity against lung cancer cells.

Iron (II) Polypyridyl Complexes as Antiglioblastoma Agents to Overcome the Blood-Brain Barrier and Inhibit Cell Proliferation by Regulating p53 and 4E-BP1 Pathways

Background and Purpose: It is urgently required to develop promising candidates to permeate across blood-brain barrier (BBB) efficiently with simultaneous disrupting vasculogenic mimicry capability of gliomas. Previously, a series of iron (II) complexes were synthesized through a modified method. Hence, the aim of this study was to evaluate anticancer activity of Fe(PIP)₃SO₄ against glioma cancer cells. Methods: Cytotoxic effects were determined via MTT assay, and IC₅₀ values were utilized to evaluate the cytotoxicity. Cellular uptake of Fe(PIP)₃SO₄ between U87 and HEB cells was conducted by subtracting content of the complex remaining in the cell culture supernatants. Propidium Iodide (PI)-flow cytometric analysis was used to analyze cell cycle proportion of U87 cells treated with Fe(PIP)₃SO₄. The reactive oxygen species levels induced by Fe(PIP)₃SO₄ were measured by 2'-deoxycoformycin (DCF) probe; ABTS assay was utilized to examine the radical scavenge capacity of Fe(PIP)₃SO₄. To study the bind efficiency to thioredoxin reductase (TrxR), Fe(PIP)₃SO₄ was introduced into solution containing TrxR. To verify if Fe(PIP)₃SO₄ could penetrate BBB, HBMEC/U87 coculture as BBB model was established, and penetrating capability of Fe(PIP)₃SO₄ was tested. In vitro U87 tumor spheroids were formed to test the permeating ability of Fe(PIP)₃SO₄. Acute toxicity and biodistribution of Fe(PIP)₃SO₄ were tested on mice for 72 h. Protein profiles associated with U87 cells treated with Fe(PIP)₃SO₄ were determined by Western blotting analysis. Results: Results showed that Fe(PIP)₃SO₄ could suppress cell proliferation by inducing G2/M phase cycle retardation and apoptotic pathways, which was related with expression of p53 and initiation factor 4E binding protein 1. In addition, Fe complex could suppress cell proliferation by downregulating reactive oxygen species levels via scavenging free radicals and interaction with TrxR. Furthermore, Fe(PIP)₃SO₄ could permeate across BBB and simultaneously inhibited the vasculogenic mimicry-channel of U87 cells, suggesting favorable antiglioblastoma efficacy. Acute toxicity manifested lower degree of the complex compared with cisplatin and temozolomide. Conclusion: Fe(PIP)₃SO₄ exhibited favorable anticancer activity against glioma cells associated with p53 and 4E binding protein 1, accompanied with negligible toxic effects on normal tissues. Herein, Fe(PIP)₃SO₄ could be developed as a promising metal-based chemotherapeutic agent to overcome BBB and antagonize glioblastomas.

Anticancer and biological properties of a Zn-2,6-diacetylpyridine bis(thiosemicarbazone) complex

Herein, to develop a multi-target anticancer metal agent and achieve a "1 + 1 > 2" pharmaceutical effect, we rationally designed and synthesized five complexes (C1-C5) by synergistically exploiting the properties of Zn(ii) and a series of modified 2,6-diacetylpyridine bis(thiosemicarbazone) ligands. By investigating the structure-activity relationships, we found that the binuclear Zn(ii) complex (C5) acts against human bladder cancer cells (T-24) with significant cytotoxicity. We subsequently determined the multiple anticancer mechanisms of C5 to T-24 cells, including inhibiting the activity of topoisomerase I (Topo I), blocking the cell cycle in the S phase, and inducing apoptosis and autophagy in T-24 cells. Furthermore, C5 inhibited the migration of T-24 cells and showed a significant cytostatic effect in the T-24 3D spheroid model.

Investigation of the cytotoxic potential of methyl imidazole-derived thiosemicarbazones and their copper(ii) complexes with dichloroacetate as a co-ligand

Investigation of the cytotoxic potential of imidazole-derived thiosemicarbazones and their copper(ii) complexes with CHCl₂CO₂⁻ as a co-ligand.

An iron(iii) complex selectively mediated cancer cell death: crystal structure, DNA targeting and in vitro antitumor activities

Three new iron(iii) complexes were prepared, and complex 3 exhibited a 14-fold higher selectivity index for HeLa vs. LO2 normal cells than cisplatin.