Cytotoxic and antimicrobial effects of indium(iii) complexes with 2-acetylpyridine-derived thiosemicarbazones

Indium(III) complexes with lapachol: cytotoxic effects against human breast tumor cells and interactions with DNA

Lapachol (2-hydroxy-3-(3-methylbut-2-en-1-yl)naphthalene-1,4-dione) is a 1,4-naphthoquinone-derived natural product that presents numerous bioactivities and was shown to have cytotoxic effects against several human tumor cells. Indium(III) complexes with a variety of ligands also exhibit antineoplastic activity. Indium(III) complexes [In(lap)Cl2].4H2O (1), [In(lap)2Cl(Et3N)] (2), [In(lap)3]·2H2O (3) [In(lap)(bipy)Cl2] bipy = 2,2'-bipyridine (4) and [In(lap)(phen)Cl2] phen = 1,10-phenanthroline (5) were obtained with 2-hydroxy-3-(3-methylbut-2-en-1-yl)naphthalene-1,4-dione (lapachol). Crystal structure determinations for (4) and (5) revealed that the indium(III) center is coordinated to two O atoms from lapachol, two N atoms from 1,10-phenanthroline or 2,2'-bipyridine, and two chloride anions, in a distorted octahedral geometry. Although both complexes (4) and (5) interacted with CT-DNA in vitro by an intercalative mode, only 5 exhibited cytotoxicity against MCF-7 and MDA-MB breast tumor cells. 1,10-phenanthroline and complex (5) presented cytotoxic effects against MCF-7 and MDA-MB cells, with complex (5) being threefold more active than 1,10-phenanthroline on MCF-7 cells. In addition, complex (5) significantly reduced the formation of MDA-MB-231 colonies in a clonogenicity assay. The foregoing results suggest that further studies on the cytotoxic effects and cellular targets of complex (5) are of utmost relevance.

"Antibacterial properties of nine indium(III) complexes of substituted pyrazoles/pyrazolate and the structural and solution characterization of the mer- and trans‑indium(III) complexes of 4-Me-pzH"

Two indium(III) complexes of formula mer-[InIIICl3(4-Me-pzH)3] and trans-[InIIICl2(4-Me-pzH)4]Cl·(4-Me-pzH)2·(H2O) were isolated from the same reaction mixture and crystallographically characterized. The two complexes exist in dynamic equilibrium and their dynamic behavior was probed by variable temperature 1H NMR spectroscopy in the 202 to 296 K range. Powder X-ray diffraction of the batch confirmed existence of both complexes in a 1:2 ratio. Antibacterial properties of both new complexes, in addition to seven other previously published indium(III) complexes, were investigated against three Gram-positive and four Gram-negative pathogenic bacterial strains. The results showed potential for the development of indium(III)-based antipseudomonal and antituberculosis drugs, with mer-[InCl3(4-Ph-pzH)3] being especially effective.

Designing a multitarget In(III) compound to overcome the resistance of lung cancer cells to cisplatin

Designing novel anticancer non-platinum metal agents is fully challenging. Herein, a series of little-known indium (In) 2-acetylpyridine thiosemicarbazone compounds as potential anticancer agents were designed, synthesized, and characterized. The hydrogen atoms at the N-4 position with the alkyl of the In compounds significantly increased cellular uptake and cytotoxicity. In(III) compounds showed significantly higher cytotoxicity toward cisplatin-resistant cell lines than cisplatin. More importantly, C4 greatly inhibited A549DDP tumor growth in a vaccinated mouse model. C4 exerted cytotoxic effects via a multitarget mechanism. First, it activated p53 and blocked the cell cycle at the S phase, which then led to weak expression levels of cyclin and related kinases and upregulation of the expression levels of cyclin-dependent kinase inhibitors. C4 also depolarized the mitochondrial membrane potential and regulated the expression of the Bcl-2 family, which then released cyt-c and activated caspase-3/8/9 to execute apoptotic pathways. Then, it inhibited telomerase through the inhibition of the expression of the c-Myc regulator gene and expression of the human telomerase reverse transcriptase. Furthermore, C4 showed excellent antimetastatic activity.

Receptors for Advanced Glycation End Products (RAGE): Promising Targets Aiming at the Treatment of Neurodegenerative Conditions

Advanced glycation end products (AGEs) are compounds formed after the non-enzymatic addition of reducing sugars to lipids, proteins, and nucleic acids. They are associated with the development of various clinical complications observed in diabetes and cardiovascular diseases, such as retinopathy, nephropathy, diabetic neuropathy, and others. In addition, compelling evidence indicates that these molecules participate in the progression of neurodegenerative diseases, such as Alzheimer's disease, Parkinson's disease, and amyotrophic lateral sclerosis. Multiple cellular and molecular alterations triggered by AGEs that could alter homeostasis have been identified. One of the main targets for AGE signaling is the receptor for advanced glycation end-products (RAGE). Importantly, this receptor is the target of not only AGEs, but also amyloid β peptides, HMGB1 (high-mobility group box-1), members of the S100 protein family, and glycosaminoglycans. The activation of this receptor induces intracellular signaling cascades that are involved in pathological processes and cell death. Therefore, RAGE represents a key target for pharmacological interventions in neurodegenerative diseases. This review will discuss the various effects of AGEs and RAGE activation in the pathophysiology of neurodegenerative diseases, as well as the currently available pharmacological tools and promising drug candidates.

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.

Pincer Complexes Derived from Tridentate Schiff Bases for Their Use as Antimicrobial Metallopharmaceuticals

Within the current challenges in medicinal chemistry, the development of new and better therapeutic agents effective against infectious diseases produced by bacteria, fungi, viruses, and parasites stands out. With chemotherapy as one of the main strategies against these diseases focusing on the administration of organic and inorganic drugs, the latter is generally based on the synergistic effect produced by the formation of metal complexes with biologically active organic compounds. In this sense, Schiff bases (SBs) represent and ideal ligand scaffold since they have demonstrated a broad spectrum of antitumor, antiviral, antimicrobial, and anti-inflammatory activities, among others. In addition, SBs are synthesized in an easy manner from one-step condensation reactions, being thus suitable for facile structural modifications, having the imine group as a coordination point found in most of their metal complexes, and promoting chelation when other donor atoms are three, four, or five bonds apart. However, despite the wide variety of metal complexes found in the literature using this type of ligands, only a handful of them include on their structures tridentate SBs ligands and their biological evaluation has been explored. Hence, this review summarizes the most important antimicrobial activity results reported this far for pincer-type complexes (main group and d-block) derived from SBs tridentate ligands.

Developing a Novel Indium(III) Agent Based on Liposomes to Overcome Cisplatin-Induced Resistance in Breast Cancer by Multitargeting the Tumor Microenvironment Components

To overcome the resistance of cancer cells to platinum-based drugs and effectively suppress tumor growth, we developed a novel indium (In) agent based on liposomes (Lips). Thus, we not only obtained an In(III) thiosemicarbazone agent (5b) with remarkable cytotoxicity by optimizing a series of In(III) thiosemicarbazone agents (1b-5b) but also successfully constructed a novel 5b-loaded Lip (5b-Lip) delivery system. Importantly, in vitro and in vivo results revealed that 5b/5b-Lip overcame the tumor cell resistance and effectively inhibited MCF-7/DDP tumor growth. In addition, Lips improved the intracellular accumulation of 5b. We also confirmed the mechanism by which 5b/5b-Lip overcomes breast cancer cell resistance. 5b/5b-Lip cannot act against DNA in cancer cells but attacks the two cell components in the tumor microenvironment, namely, by inducing apoptosis and lethal autophagy of cancer cells and resetting tumor-promoting M2 macrophages to the tumor-killing M1 phenotype.

Antifungal activity of thiosemicarbazones, bis(thiosemicarbazones), and their metal complexes

Fungi are ubiquitous in nature, and typically cause little or no environmental or pathogenic damage to their plant, animal, and human hosts. However, a small but growing number of pathogenic fungi are spreading world-wide at an alarming rate threatening global ecosystem health and proliferation. Many of these emerging pathogens have developed multi-drug resistance to front line therapeutics increasing the urgency for the development of new antifungal agents. This review examines the development of thiosemicarbazones, bis(thiosemicarbazones), and their metal complexes as potential antifungal agents against more than 65 different fungal strains. The fungistatic activity of the compounds are quantified based on the zone of inhibition, minimum inhibitory concentration, or growth inhibition percentage. In this review, reported activities were standardized based on molar concentrations to simplify comparisons between different compounds. Of all the fungal strains reported in the review, A. niger in particular was very resistant towards a majority of tested compounds. Our analysis of the data shows that metal complexes are typically more active than non-coordinated ligands with copper(II) and zinc(II) complexes generally displaying the highest activity.

Superior antibacterial activity of gallium based liquid metals due to Ga3+ induced intracellular ROS generation

Gallium metals demonstrate enhanced antibacterial activity compared to gallium nitrate with the same gallium ion concentration.

Molecular events and cytotoxic effects of a novel thiosemicarbazone derivative in human leukemia and lymphoma cell lines

The present study aimed to investigate the cytotoxic effect of 38 new thiosemicarbazone derivatives on hematological neoplastic cells lines and to select the most effective compounds to investigate the main molecular mechanisms involved in cell death. Cytotoxicity screening on Daudi and Jurkat cells revealed that only compound 1b met the selection criteria; therefore, it was chosen for further investigation. Cell viability of Daudi, Jurkat, Molt-4, Namalwa, K562, and MM.1S cell lines decreased in a concentration- and time-dependent manner after compound1b incubation; nevertheless the compound neither caused significant hemolysis nor reduction in peripheral blood mononuclear cell viability. Although no changes were observed on cell cycle or Ki-67 expression, compound1b induced apoptotic-like cell death with mitochondrial involvement, Bax/Bcl-2 inversion, AIF release, survivin inhibition, and caspase-3 activation in both Daudi and Jurkat cells. Furthermore, the compound reduced NFκB expression in Jurkat cells. In Daudi cells, compound1b also decreased CHOP, Akt, pAkt, and MAPK/ERK2 expression, thereby suggesting modulation of UPR, PI3K/Akt/mTOR, and MAPK/ERK signaling pathways. Finally, the compound was able to reduce the cell viability of samples collected from patients with different lymphoid neoplasms subtypes, showing that thiosemicarbazones derivatives could be used in the development of new drugs with anticancer activity.

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.

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.

A Magnetic Adsorbent for the Removal of Cationic Dyes from Wastewater

In this article, a study was presented on the adsorption activity of a new nanocomposite particle Fe₃O₄@1, which was synthesized by combining [Cu(HL)₂]₂H₂[P₂Mo₅O23]·10H₂O (1) (HL = 2-acetylpyridine semicarbazone) and Fe₃O₄ nanoparticles. Transmission electron microscopy and X-ray powder diffraction analyses revealed that Fe₃O₄@1 possessed high crystallinity with an average particle size of 19.1 nm. The adsorption activity of the as-prepared Fe₃O₄@1 was investigated by photometrically monitoring the removal of methylene blue, rhodamine B, safranine T, gentian violet, fuchsin basic, and methyl orange from aqueous solutions. Significantly, we could easily separate Fe₃O₄@1 from the reaction media by applying an external magnet. Furthermore, the recycling performance was observed using methylene blue, revealing the recyclability and high stability of Fe₃O₄@1. It was shown that Fe₃O₄@1 is a promising candidate material for adsorbing cationic dyes in aqueous media.

Neutron activation of In(iii) complexes with thiosemicarbazones leads to the production of potential radiopharmaceuticals for the treatment of breast cancer

^114mIn(iii) complexes with 2-acetylpyridine-derived thiosemicarbazones show potent cytotoxic activity.