Investigating the Biological Potency of Nitazoxanide-Based Cu(II), Ni(II) and Zn(II) Complexes Synthesis, Characterization and Anti-COVID-19, Antioxidant, Antibacterial and Anticancer Activities

Tailoring functionalized 2,3-diaza-1,3-butadienes for high-energy and insensitive applications

The heat of formation (HOF), detonation performance, electronic properties, thermal stability, impact energy and explosive power of a series of highly functionalized 2,3-diaza-1,3-butadienes were studied using density functional theory. HOF values of all the designed compounds were positive. Among the 100 compounds, more than 50 % exhibited a density equal to or greater than 1.9 g cm-3. There was close agreement in the calculated value of density, detonation performance and impact energy of traditional explosive RDX, HMX and CL-20 with the experimental value. The predicted values of detonation velocity and pressure indicated that about 45 compounds possessed values higher than that of 1,3,5-trinitro-1,3,5-triazacyclohexane (RDX), among which 20 compounds had higher impact energy than HMX. Five compounds were identified as potential front-runners with superior detonation performance greater than CL-20, together with impact energy higher than HMX. Thus compounds with improved properties were designed by the adoption of strategies that involved the incorporation of diverse explosophores and nitrogen atoms in the ring and the framework. Our study proves that this work holds immense potential in the development of high-energetic density materials with promising properties.

Coumarin-imidazopyridine hybrids and their first-in-class ZnII metal complexes as potent dual entry and replication inhibitors of Zika viral infection

In this study, we synthesized and characterized a series of coumarin-imidazopyridine hybrid ligands (HL1-HL4) and their corresponding Zn(II) complexes (C1-C4). The ligands were synthesized via a two-step process in 56-90 % yields. The resulting ligands, were utilized to form Zn(II) complexes, characterized by conductivity measurements, HRMS, IR, 1H NMR spectroscopy and X-ray diffractions. Biological evaluations revealed that these compounds exhibited potent antiviral activity against Zika virus (ZIKV), with EC50 values ranging from 0.55 to 4.8 µM and SI of up to 1490. Notably, the complexes (the first-in-class Zn(II) anti-ZIKV complexes) generally displayed enhanced activity compared to their respective ligands, with some compounds outperforming the reference antiviral, ribavirin. The Time of Addition assay suggested that while some compounds interfere with both viral entry (with a virucidal component) and replication phases, other only acted in replication phases. These results together with molecular modeling studies on ZIKV Envelope protein and ZIKV NS2B-NS3 offered insights for their mode of actions and further optimizations.

Metabolites from Marine Macroorganisms of the Red Sea Acting as Promoters or Inhibitors of Amylin Aggregation

Amylin is part of the endocrine pancreatic system that contributes to glycemic control, regulating blood glucose levels. However, human amylin has a high tendency to aggregate, forming isolated amylin deposits that are observed in patients with type 2 diabetes mellitus. In search of new inhibitors of amylin aggregation, we undertook the chemical analyses of five marine macroorganisms encountered in high populations in the Red Sea and selected a panel of 10 metabolites belonging to different chemical classes to evaluate their ability to inhibit the formation of amyloid deposits in the human amylin peptide. The thioflavin T assay was used to examine the kinetics of amyloid aggregation, and atomic force microscopy was employed to conduct a thorough morphological examination of the formed fibrils. The potential ability of these compounds to interact with the backbone of peptides and compete with β-sheet formation was analyzed by quantum calculations, and the interactions with the amylin peptide were computationally examined using molecular docking. Despite their structural similarity, it could be observed that the hydrophobic and hydrogen bond interactions of pyrrolidinones 9 and 10 with the protein sheets result in one case in a stable aggregation, while in the other, they cause distortion from aggregation.

Cu(II) complexes with a salicylaldehyde derivative and α-diimines as co-ligands: synthesis, characterization, biological activity. Experimental and theoretical approach

Copper(II) complexes with an α-diimine show a wide variety of biological activities, such as antibacterial, antifungal, antioxidant and anticancer. In this work, we synthesized and structurally characterized two novel Cu(II) complexes with methyl 3-formyl-4-hydroxybenzoate (HL) and α-diimines: 2,2'-bipyridine (bipy) and 1,10-phenanthroline (phen). Crystal structure analysis shows that the formulas of the compounds are [Cu(bipy)(L)(BF4)] (1) and [Cu(phen)(L)(H2O)](BF4)·H2O (2), with BF4- as a ligand in complex 1, which is rarely coordinated to metals. Both complexes have a square pyramidal geometry, while DFT calculations showed that the most stable structures of complexes 1 and 2 in a water/DMSO mixture are square-planar derivatives [Cu(bipy)(L)]+ and [Cu(phen)(L)]+. The antibacterial activity of compounds was evaluated in vitro on four Gram-negative and four Gram-positive bacterial strains. Complex 2 showed greater antibacterial activity towards all bacterial strains comparable to the control compound Amikacin. Complex 2 exerted a strong cytotoxic effect against the tested cancer cell lines (IC50 values ranging from 0.32 to 0.44 μM). Both complexes caused apoptotic cell death in HeLa cells and a noticeable in vitro antiangiogenic effect. In the concentration range of 5 to 100 μM, the complexes showed the absence of a genotoxic effect and displayed a protective effect against oxidative DNA damage induced by H2O2 in human peripheral blood cells. The interaction between the compounds and calf-thymus DNA was evaluated by diverse techniques suggesting a tight binding, which was also confirmed by molecular docking. In addition, it was found that the complexes bind tightly and reversibly to bovine and human serum albumin.