Novel Zinc(II) Complexes [Zn(atc-Et)₂] and [Zn(atc-Ph)₂]: In Vitro and in Vivo Antiproliferative Studies

Zinc(II) complexes bearing N,N,S ligands: Synthesis, crystal structure, spectroscopic analysis, molecular docking and biological investigations about its antifungal activity

In the present work, the synthesis, characterization, antifungal activity, molecular docking study and in silico approach of five thiosemicarbazone derivatives and their corresponding zinc(II) complexes are described. The compounds were characterized by elemental analysis, IR, UV-Vis and NMR spectroscopic measurements, molar conductivity measurements, emission spectra, high-resolution mass spectrometry and X ray study. The antifungal activity of the free ligands and synthesized compounds was preliminarily evaluated against Candida albicans (ATCC 90028), Candida tropicalis (ATCC 13803) and Candida glabrata (ATCC 2001), by the minimum inhibitory concentration (MIC) assay. Two complexes, 4 (MIC = 3.18 to 6.37 μM) and 5 (MIC = 25.95 μM for all) showed promising results, being highly active against all strains evaluated. The X-ray analyses shown that the complex 2 crystallizes in the centrosymmetric space group P2₁/c of the monoclinic system and the coordination sphere around zinc(II) atom is better described as slightly distorted octahedral. The Hirshfeld surface (HS) analysis showed that non-classical H···H and C···H/H···C contacts contribute with 65.9% while the S···H and N···H (21%) and Cl···H and O···H interactions (12%) complete the HS area. The molecular docking results, performed against CYP51 enzyme (sterol 14α-demethylase) of C. albicans and C. glabrata shows that the complexes 4 (ΔG = -10.75 and - 12.90 kcal/ mol) and 5 (ΔG = -11.12 and - 14.53 kcal/ mol) showed the highest binding free energies of all compounds. The ADME-Tox (absorption, distribution, metabolism, excretion and toxicity) in silico parameters evaluated showed promising results for all compounds.

Efficacy of Prednisolone/Zn Metal Complex and Artemisinin Either Alone or in Combination on Lung Functions after Excessive Exposure to Electronic Cigarettes Aerosol with Assessment of Antibacterial Activity

The use of transition metal complexes as therapeutic compounds has become more and more pronounced. These complexes offer a great diversity of uses in their medicinal applications. Electronic cigarettes (ECs) are an electronic nicotine delivery system that contain aerosol (ECR). The ligation behavior of prednisolone, which is a synthetic steroid that is used to treat allergic diseases and asthma arthritis, and its Zn (II) metal complex were studied and characterized based on elemental analysis, molar conductance, Fourier-transform infrared (FT-IR) spectra, electronic spectra, XRD, scanning electron microscopy (SEM), energy dispersive x-ray (EDX), and transmission electron microscopy (TEM). The FT-IR spectral data revealed that PRD acts as a mono-dentate ligand via oxygen atoms of the carbonyl group. Electronic and FT-IR data revealed that the PRD/Zn (II) metal complexes have square planner geometry. Artemisinin (ART) is the active main constituent of Artemisia annua extract, and it has been demonstrated to exert an excellent antimalarial effect. The experiment was performed on 40 male mice that were divided into the following 7 groups: Control, EC group, PRD/Zn, ART, EC plus PRD/Zn, EC plus ART, and PRD plus combination of PRD/Zn and ART. Serum CRP, IL-6, and antioxidants biomarkers were determined. Pulmonary tissue histology was evaluated. When in combination with Zn administration, PRD showed potent protective effects against pulmonary biochemical alterations induced by ECR and suppressed severe oxidative stress and pulmonary structure alterations. Additionally, PRD/Zn combined with ART prevented any stress on the pulmonary tissues via antioxidant regulation, reducing inflammatory markers CRP and Il-6 and improving antioxidant enzymatic levels more than either PRD or ART alone. Therefore, PRD/Zn combined with ART produced a synergistic effect against any sort of oxidative stress and also improved the histological structure of the lung tissues. These findings are of great importance for saving pulmonary function, especially during pandemic diseases, such as during the COVID-19 pandemic.

In vitro biological and in silico molecular docking and ADME studies of a substituted triazine-coordinated cadmium(II) ion: efficient cytotoxicity, apoptosis, genotoxicity, and nuclease-like activity plus binding affinity towards apoptosis-related proteins

A cadmium(II) complex containing dppt ligand with the formula [CdCl₂(dppt)₂], where dppt is 5,6-diphenyl-3-(2-pyridyl)-1,2,4-triazine was synthesized, elucidated and submitted to in vitro cytotoxicity studies against human breast (MCF-7), glioblastoma (U-87), and lung (A549) cancer cell lines as well as mouse embryo normal cell line (NIH/3T3), in comparison with cisplatin employing MTT assay over 24 and 48 h. The complex exhibited the highest cytotoxic effect against MCF-7 cells among the other three cell lines with IC₅₀ values of 8.7 ± 0.5 (24 h) and 1.2 ± 0.7 µM (48 h). Significantly, flow cytometric assessment of the complex-treated MCF-7 and U-87 cells demonstrated a dose-dependent induced apoptotic cell death. The cellular morphological changes were in concord with cytotoxicity and flow cytometric results. The results of comet assay showed that the complex is able to induce DNA damage in MCF-7 cells. These observations are of importance, as sustained damage to cellular DNA could lead to apoptotic cell death. The results of DNA-binding studies indicated that the complex fits into the DNA minor groove and interacts with DNA via a partial intercalation. Moreover, the complex was able to efficiently cleave pUC19 DNA through a hydrolytic mechanism. The binding affinity between the complex and apoptosis-relevant protein targets including APAF1, Bax, Bcl-2, Cas3, Cas7, and Cas9 was evaluated through molecular docking studies. In silico virtual studies revealed the complex's strong affinity towards apoptosis-related proteins; therefore the complex can act as a potential apoptosis inducer. Physicochemical, pharmacokinetics, lipophilicity, drug-likeness, and medicinal chemistry properties of the complex were also predicted through in silico absorption, distribution, metabolism and excretion studies.

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).

Fragmentation Study, Dual Anti-Bactericidal and Anti-Viral Effects and Molecular Docking of Cobalt(III) Complexes

Considering our previous findings on the remarkable activity exhibited by cobalt(III) with 2-acetylpyridine-N(4)-R-thiosemicarbazone (Hatc-R) compounds against Mycobacterium tuberculosis, the present study aimed to explored new structure features of the complexes of the type [Co(atc--R)₂]Cl, where R = methyl (Me, 1) or phenyl (Ph, 2) (¹³C NMR, high-resolution mass spectrometry, LC-MS/MS, fragmentation study) together with its antibacterial and antiviral biological activities. The minimal inhibitory and minimal bactericidal concentrations (MIC and MBC) were determined, as well as the antiviral potential of the complexes on chikungunya virus (CHIKV) infection in vitro and cell viability. [Co(atc-Ph)₂]Cl revealed promising MIC and MBC values which ranged from 0.39 to 0.78 µg/mL in two strains tested and presented high potential against CHIKV by reducing viral replication by up to 80%. The results showed that the biological activity is strongly influenced by the peripheral substituent groups at the N(4) position of the atc-R^1- ligands. In addition, molecular docking analysis was performed. The relative binding energy of the docked compound with five bacteria strains was found in the range of -3.45 and -9.55 kcal/mol. Thus, this work highlights the good potential of cobalt(III) complexes and provide support for future studies on this molecule aiming at its antibacterial and antiviral therapeutic application.

Palladium(ii) complexes with thiosemicarbazones derived from pyrene as topoisomerase IB inhibitors

New palladium complexes with thiosemicarbazonate ligands derived from pyrene exhibit potent antiproliferative activity against A2780 and cisplatin-resistant A2780Cis human ovarian cancer cells, which is dependent on substituent groups of the thiosemicarbazone ligands. Cellular accumulation and distribution studies confirmed that palladium enters the cell nucleus. DNA and topoisomerase IB studies show that one complex is a potent TopIB inhibitor, with selectivity for cancer versus normal cells.

Computational studies, design and synthesis of Pd(II)-based complexes: Allosteric inhibitors of the Human Topoisomerase-IIα

Herein, a robust docking protocol was developed by using a low-cost workflow to highlight the modulation at ATPase domain from Human Topoisomerase-IIα (TOP2A) towards four novel Pd(II)-complexes bearing N,S-donor ligands. In vitro TOP2A inhibition assay confirmed the ability of them to prevent the enzyme functions into concentration ranging at 6.25-25μM. These results exhibited more effectivity than anticancer agent etoposide (35μM) and merbarone (40-50μM). The compounds were screened via Resazurin assay against MCF-7, MDA-MB-231 (Human breast), DU-145 (Human prostate), A549 (Human lung) and Cal27 (Human tongue) tumor cell lines revealing great cytotoxic effects, primarily to MCF-7 (IC₅₀=1.81-4.46μM). As well, 1-4 exhibited their selectivity index (SI) higher than cisplatin against HEK-293 (human kidney) normal cells, at least 11.6-fold (SI_1-4=1.4-5.0; SI_cis=0.12). Further, Red Blood Cell hemolytic test suggested in vitro non-toxic character for compound 4, previously evaluated as the most effective TOP2A inhibitor.

Synthesis of 2-acetylpyridine-N-substituted thiosemicarbazonates of copper(ii) with high antimicrobial activity against methicillin resistant S. aureus, K. pneumoniae 1 and C. albicans

The basic interest in the present study pertains to developing metal based antimicrobial agents, as several microorganisms have built resistance to the conventional drugs.

Nanostructured lipid carriers for incorporation of copper(II) complexes to be used against Mycobacterium tuberculosis

Tuberculosis (TB) is a disease caused by Mycobacterium tuberculosis. Cessation of treatment before the recommended conclusion may lead to the emergence of multidrug-resistant strains. The aim of this study was to develop nanostructured lipid carriers (NLCs) for use in the treatment of M. tuberculosis. The NLCs comprised the following lipid phase: 2.07% polyoxyethylene 40 stearate, 2.05% caprylic/capric triglyceride, and 0.88% polyoxyl 40 hydrogenated castor oil; the following aqueous phase: 3.50% poloxamer 407 (F1-F6), and 0.50% cetyltrimethylammonium bromide (F7-F12); and incorporated the copper(II) complexes [CuCl₂(INH)₂]·H₂O (1), [Cu(NCS)₂(INH)₂]·5H₂O (2), and [Cu(NCO)₂(INH)₂]·4H₂O (3) to form compounds F11.1, F11.2, and F11.3, respectively. The mean diameter of F11, F11.1, F11.2, and F11.3 ranged from 111.27±21.86 to 134.25±22.72 nm, 90.27±12.97 to 116.46±9.17 nm, 112.4±10.22 to 149.3±15.82 nm, and 78.65±6.00 to 122.00±8.70 nm, respectively. The polydispersity index values for the NLCs ranged from 0.13±0.01 to 0.30±0.09. The NLCs showed significant changes in zeta potential, except for F11.2, with F11, F11.1, F11.2, and F11.3 ranging from 18.87±4.04 to 23.25±1.13 mV, 17.03±1.77 to 21.42±1.87 mV, 20.51±1.88 to 22.60±3.44 mV, and 17.80±1.96 to 25.25±7.78 mV, respectively. Atomic force microscopy confirmed the formation of nanoscale spherical particle dispersions by the NLCs. Differential scanning calorimetry determined the melting points of the constituents of the NLCs. The in vitro activity of copper(II) complex-loaded NLCs against M. tuberculosis H₃₇R_v showed an improvement in the anti-TB activity of 55.4, 27.1, and 41.1 times the activity for complexes 1, 2, and 3, respectively. An in vivo acute toxicity study of complex-loaded NLCs demonstrated their reduced toxicity. The results suggest that NLCs may be a powerful tool to optimize the activity of copper(II) complexes against M. tuberculosis.