Palladium(II) complexes bearing thiosemicarbazone and phosphines as inhibitors of DNA-Topoisomerase II enzyme: Synthesis, characterizations and biological studies

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.

Designing, characterization, biological, DFT, and molecular docking analysis for new FeAZD, NiAZD, and CuAZD complexes incorporating 1-(2-hydroxyphenylazo)- 2-naphthol (H2AZD)

Herien, three new Fe(III) (FeAZD), Ni(II) (NiAZD), and Cu(II) (CuAZD) complexes were synthesized and characterized using various physicochemical and spectroscopic approaches. The H₂AZD ligand acted as a bi-basic bi-dentate NO ligand in a 1:1 molar ratio. The results revealed that the FeAZD and CuAZD complexes had octahedral geometry, while the NiAZD had a tetrahedral geometry. The optimized geometry, HOMO and LUMO analysis of the ligand and its metal complexes was determined via Density functional theory (DFT) using the B3LYP with 6-311 G(d,p), and LanL2DZ level of theory. The FeAZD, NiAZD and CuAZD had lower energy gap, 7.40, 7.93 and 7.06 eV, respectively, than the free ligand (9.58 eV), which proposed that CuAZD was more active one. The free ligand and its metal complexes were in vitro investigated for their antibacterial and antifungal activity. The results illustrated that the metal complexes had higher antibacterial and antifungal activity than the free ligand. More specifically, the CuAZD demonstrated good antibacterial activity against E. coli, P. aeruginosa, S. aureus, B. cereus, and A. flavus, T. rubrum, and C. albicans, with activity indexes of 72.22%, 65.01%, 77.78%, and 72.22%, 63.16%, 59.09%, and 61.90%, respectively. Also, the metal complexes showed lower MIC (6.25-3.125 ppm) compared to the free ligand (about 50 ppm). Finally, molecular docking was utilized to investigate the ability of the free ligand and its metal complexes to inhibit the growth of E. coli (PDB ID: 5iq9). The results showed that the CuAZD had the highest binding affinity to the receptor, with a more negative docking score of - 7.05 Kcal/mol, and lower inhibition constant (Ki) of 6.90 µM. That is indicating that it may be the most effective at inhibiting the growth of E. coli (PDB ID: 5iq9).

Two out of Three Musketeers Fight against Cancer: Synthesis, Physicochemical, and Biological Properties of Phosphino CuI, RuII, IrIII Complexes

Two novel phosphine ligands, Ph2PCH2N(CH2CH3)3 (1) and Ph2PCH2N(CH2CH2CH2CH3)2 (2), and six new metal (Cu(I), Ir(III) and Ru(II)) complexes with those ligands: iridium(III) complexes: Ir(η5-Cp*)Cl2(1) (1a), Ir(η5-Cp*)Cl2(2) (2a) (Cp*: Pentamethylcyclopentadienyl); ruthenium(II) complexes: Ru(η6-p-cymene)Cl2(1) (1b), Ru(η6-p-cymene)Cl2(2) (2b) and copper(I) complexes: [Cu(CH3CN)2(1)BF4] (1c), [Cu(CH3CN)2(2)BF4] (2c) were synthesized and characterized using elemental analysis, NMR spectroscopy, and ESI-MS spectrometry. Copper(I) complexes turned out to be highly unstable in the presence of atmospheric oxygen in contrast to ruthenium(II) and iridium(III) complexes. The studied Ru(II) and Ir(III) complexes exhibited promising cytotoxicity towards cancer cells in vitro with IC50 values significantly lower than that of the reference drug-cisplatin. Confocal microscopy analysis showed that Ru(II) and Ir(III) complexes effectively accumulate inside A549 cells with localization in cytoplasm and nuclei. A precise cytometric analysis provided clear evidence for the predominance of apoptosis in induced cell death. Furthermore, the complexes presumably induce the changes in the cell cycle leading to G2/M phase arrest in a dose-dependent manner. Gel electrophoresis experiments revealed that Ru(II) and Ir(III) inorganic compounds showed their unusual low genotoxicity towards plasmid DNA. Additionally, metal complexes were able to generate reactive oxygen species as a result of redox processes, proved by gel electrophoresis and cyclic voltamperometry. In vitro cytotoxicity assays were also carried out within multicellular tumor spheroids and efficient anticancer action on these 3D assemblies was demonstrated. It was proven that the hydrocarbon chain elongation of the phosphine ligand coordinated to the metal ions does not influence the cytotoxic effect of resulting complexes in contrast to metal ions type.

Aminothiazole-Linked Metal Chelates: Synthesis, Density Functional Theory, and Antimicrobial Studies with Antioxidant Correlations

During the current study, the new aminothiazole Schiff base ligands (S1 ) and (S2 ) were designed by reacting 1,3-thiazol-2-amine and 6-ethoxy-1,3-benzothiazole-2-amine separately with 3-methoxy-2-hydroxybenzaldehyde in good yields (68-73%). The ligands were characterized through various analytical, physical, and spectroscopic (FT-IR, UV-Vis, 1H and 13C NMR, and MS) methods. The ligands were exploited in lieu of chelation with bivalent metal (cobalt, nickel, copper, and zinc) chlorides in a 1:2 (M:L) ratio. The spectral (UV-Vis, FT-IR, and MS), as well as magnetic, results suggested their octahedral geometry. The theoretically optimized geometrical structures were examined using the M06/6-311G+(d,p) function of density function theory. Their bioactive nature was designated by global reactivity parameters containing a high hardness (η) value of 1.34 eV and a lower softness (σ) value of 0.37 eV. Different microbial species were verified for their potency (in vitro), revealing a strong action. The Gram-positive Micrococcus luteus and Gram-negative Escherichia coli gave the highest activities of 20 and 21 mm for compounds (8) and (7), respectively. The antifungal activity against the Aspergillus niger and Aspergillus terreus species gave the highest activities of 20 and 18 mm for compounds (7) and (6), respectively. The antioxidant activity, evaluated as DPPH and ferric reducing power, gave the highest inhibition (%) as 72.0 ± 0.11% (IC50 = 144 ± 0.11 μL) and 66.3% (IC50 = 132 ± 0.11 μL) for compounds (3) and (8), respectively. All metal complexes were found to be more biocompatible than free ligands due to their chelation phenomenon. The energies of LUMOs had a link with their activities.

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).

Inhibition of histone deacetylases, topoisomerases and epidermal growth factor receptor by metal-based anticancer agents: Design & synthetic strategies and their medicinal attributes

Metal-based inhibitors of histone deacetylases (HDAC), DNA topoisomerases (Topos) and Epidermal Growth Factor Receptor (EGFR) have demonstrated their cytotoxic potential against various cancer types such as breast, lung, uterus, colon, etc. Additionally, these have proven their role in resolving the resistance issues, enhancing the affinity, lipophilicity, stability, and biocompatibility and therefore, emerged as potential candidates for molecularly targeted therapeutics. This review focusses on nature and role of metals and organic ligands in tuning the anticancer activity in multiple modes of inhibition considering HDACs, Topos or EGFR as one of the primary targets. The conceptual design and synthetic approaches of platinum and non-platinum metal complexes comprising of chiefly ruthenium, rhodium, palladium, copper, iron, nickel, cobalt, zinc metals coordinated with organic scaffolds, along with their biological activity profiles, structure-activity relationships (SARs), docking studies, possible modes of action, and their scope and limitations are discussed in detail.