Flexible vs. rigid bis(2-benzimidazolyl) ligands in Cu(II) complexes: Impact on redox chemistry and oxidative DNA cleavage activity

Gold(III) complexes with thiosemicarbazone ligands: insights into their cytotoxic effects on lung cancer cells

Cancer continues to pose a global threat, underscoring the urgent need for more effective and safer treatment options. Gold-based compounds have recently emerged as promising candidates due to their diverse range of biological activities. In this study, three gold(III) complexes derived from thiosemicarbazone ligands have been synthesized, fully characterized, including their X-ray crystal structures. We conducted initial mode-of-action studies on DNA and BSA, followed by a comprehensive investigation into the cytotoxic effects of these novel gold(III) complexes on lung cancer cells (A549, H2052, and H28). The results demonstrated a concentration-dependent cytotoxic response, with H28 cells exhibiting the highest sensitivity to the treatment. Furthermore, the analysis of the cell cycle revealed that these compounds induce cell cycle arrest and promote apoptosis as a response to treatment. We also observed distinct morphological changes and increased oxidative stress, contributing significantly to cell death. Notably, these complexes exhibited the ability to suppress interleukin-6 production in mesothelioma cell lines, and this highlights their anti-inflammatory potential. To gain an initial understanding of cytotoxicity on healthy cells, hemolysis tests were conducted against human blood cells, with no evidence of hemolysis. Furthermore, a toxicity assessment through the in vivo Galleria mellonella model underscored the absence of detectable toxicity. These findings prove that these complexes are promising novel therapeutic agents for lung cancer.

Nuclease-like metalloscissors: Biomimetic candidates for cancer and bacterial and viral infections therapy

Despite the extensive and rapid discovery of modern drugs for treatment of cancer, microbial infections, and viral illnesses; these diseases are still among major global health concerns. To take inspiration from natural nucleases and also the therapeutic potential of metallopeptide antibiotics such as the bleomycin family, artificial metallonucleases with the ability of promoting DNA/RNA cleavage and eventually affecting cellular biological processes can be introduced as a new class of therapeutic candidates. Metal complexes can be considered as one of the main categories of artificial metalloscissors, which can prompt nucleic acid strand scission. Accordingly, biologists, inorganic chemists, and medicinal inorganic chemists worldwide have been designing, synthesizing and evaluating the biological properties of metal complexes as artificial metalloscissors. In this review, we try to highlight the recent studies conducted on the nuclease-like metalloscissors and their potential therapeutic applications. Under the light of the concurrent Covid-19 pandemic, the human need for new therapeutics was highlighted much more than ever before. The nuclease-like metalloscissors with the potential of RNA cleavage of invading viral pathogens hence deserve prime attention.

Head-to-head bisbenzazole derivatives as antiproliferative agents: design, synthesis, in vitro activity, and SAR analysis

In the present work, a series of bisbenzazole derivatives were designed and synthesized as antiproliferative agents. The antiproliferative activity of these compounds was investigated using MTT assay. Bisbenzazole derivatives showed significant antiproliferative activity against all the four tested cancer cell lines. Among the various bisbenzazole derivatives, bisbenzoxazole derivatives exhibited the most promising anticancer activity followed by bisbenzimidazole and bisbenzothiazole derivatives. All the derivatives were found to be less toxic as compared to methotrexate (positive control) in normal human cells, indicating selective and efficient antiproliferative activity of these bisbenzazole derivatives. The structure-activity relationships of heteroaromatic systems and linkers present in bisbenzazole derivatives were analyzed in detail. In silico ADMET prediction revealed that bisbenzazole is a drug-like small molecule with a favorable safety profile. Compound 31 is a potential antiproliferative hit compound that exhibits unique cytotoxic activity distinct from methotrexate. Twenty-one bisbenzoxazole derivatives have been designed synthesized and evaluated to be an antiproliferative activity against four human tumor cell lines.

Incorporation of β-Alanine in Cu(II) ATCUN Peptide Complexes Increases ROS Levels, DNA Cleavage and Antiproliferative Activity*

Redox‐active Cu(II) complexes are able to form reactive oxygen species (ROS) in the presence of oxygen and reducing agents. Recently, Faller et al. reported that ROS generation by Cu(II) ATCUN complexes is not as high as assumed for decades. High complex stability results in silencing of the Cu(II)/Cu(I) redox cycle and therefore leads to low ROS generation. In this work, we demonstrate that an exchange of the α‐amino acid Gly with the β‐amino acid β‐Ala at position 2 (Gly2→β‐Ala2) of the ATCUN motif reinstates ROS production (^•OH and H₂O₂). Potentiometry, cyclic voltammetry, EPR spectroscopy and DFT simulations were utilized to explain the increased ROS generation of these β‐Ala2‐containing ATCUN complexes. We also observed enhanced oxidative cleavage activity towards plasmid DNA for β‐Ala2 compared to the Gly2 complexes. Modifications with positively charged Lys residues increased the DNA affinity through electrostatic interactions as determined by UV/VIS, fluorescence, and CD spectroscopy, and consequently led to a further increase in nuclease activity. A similar trend was observed regarding the cytotoxic activity of the complexes against several human cancer cell lines where β‐Ala2 peptide complexes had lower IC₅₀ values compared to Gly2. The higher cytotoxicity could be attributed to an increased cellular uptake as determined by ICP‐MS measurements.

Antimicrobial peptides: mechanism of action, activity and clinical potential

The management of bacterial infections is becoming a major clinical challenge due to the rapid evolution of antibiotic resistant bacteria. As an excellent candidate to overcome antibiotic resistance, antimicrobial peptides (AMPs) that are produced from the synthetic and natural sources demonstrate a broad-spectrum antimicrobial activity with the high specificity and low toxicity. These peptides possess distinctive structures and functions by employing sophisticated mechanisms of action. This comprehensive review provides a broad overview of AMPs from the origin, structural characteristics, mechanisms of action, biological activities to clinical applications. We finally discuss the strategies to optimize and develop AMP-based treatment as the potential antimicrobial and anticancer therapeutics.

Two new lanthanide complexes with 5-(Pyrazol-1-yl)nicotinic acid: Structures and their anti-cancer properties

Two new lanthanide complexes [PrL₂(EA)₂]NO₃ (complex 1) and [SmL₂(EA)₂]NO₃ (complex 2) (H₂L = 5-(Pyrazol-1-yl)nicotinic acid, EA = CH₃CH₂OH) were synthesized. The structures were characterized by single crystal X-ray and elemental analysis. The interaction between the complex and fish sperm DNA(FS-DNA) was monitored using ultraviolet and fluorescence spectroscopy, and the binding constants were determined. Both complexes showed the ability to effectively bind DNA, and the molecular docking technology was used to simulate the binding of the complex and DNA. In addition, through the annexin V-Fluorescein Isothiocyanate(FITC)/ Propidium Iodide (PI) test experiment, tetrazollium [3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide(MTT) in vitro test, and cell morphology apoptosis studies, it was shown that the complex can effectively induce HeLa tumor cell apoptosis. Compared with cisplatin and complex, complex 1 shows significant cancer cell inhibition, and we hope that this new type of complex will open up new ways for the next generation of drugs in biomedical applications.

Antimicrobial Peptides and Copper(II) Ions: Novel Therapeutic Opportunities

The emergence of new pathogens and multidrug resistant bacteria is an important public health issue that requires the development of novel classes of antibiotics. Antimicrobial peptides (AMPs) are a promising platform with great potential for the identification of new lead compounds that can combat the aforementioned pathogens due to their broad-spectrum antimicrobial activity and relatively low rate of resistance emergence. AMPs of multicellular organisms made their debut four decades ago thanks to ingenious researchers who asked simple questions about the resistance to bacterial infections of insects. Questions such as "Do fruit flies ever get sick?", combined with pioneering studies, have led to an understanding of AMPs as universal weapons of the immune system. This review focuses on a subclass of AMPs that feature a metal binding motif known as the amino terminal copper and nickel (ATCUN) motif. One of the metal-based strategies of hosts facing a pathogen, it includes wielding the inherent toxicity of copper and deliberately trafficking this metal ion into sites of infection. The sudden increase in the concentration of copper ions in the presence of ATCUN-containing AMPs (ATCUN-AMPs) likely results in a synergistic interaction. Herein, we examine common structural features in ATCUN-AMPs that exist across species, and we highlight unique features that deserve additional attention. We also present the current state of knowledge about the molecular mechanisms behind their antimicrobial activity and the methods available to study this promising class of AMPs.