Macrocyclic complexes: synthesis, characterization, antitumor and DNA binding studies

M. A Comprehensive Review of the Biological Activities of Medicinal Metal Complexes Synthesized From Quinoline Scaffolds

The compelling attributes of quinoline scaffolds in medicinal compounds have garnered considerable attention from researchers, due to their notable biological efficacy, biocompatibility, and distinctive photophysical properties. Quinoline complexes, in particular, have emerged as significant entities, demonstrating a wide array of medicinal properties, including antibacterial, antifungal, antiviral, anticancer, anthelmintic, anti-HIV, antioxidant, antituberculosis, and antimalarial activities. In addition, they showed promise in photodynamic and neurological studies, along with strong DNA-binding capabilities. In recent years (2010-2023), substantial progress has been made in understanding quinoline complexes. Key aspects such as the lipophilicity, of metal complexes, enzymatic drug degradation factors influencing inhibition, drug performance, disruption of target cell growth, and their impact on DNA have been thoroughly investigated. Researchers have employed advanced methodologies including fluorescent imaging, determination of MIC and IC50 values, hydrodynamic and spectrophotometric techniques, in silico and in vitro studies, and cytotoxicity assessments using the MTT method, to significantly enhance our understanding of these complexes. Recent findings indicated that the interaction of quinoline complexes with viral proteins and their ability to disrupt enzyme-viral DNA relationships have made them powerful therapeutic agents for severe diseases including cancer, AIDS, and coronaviruses, as well as various neurological and microbial infections. It is anticipated that these explorations will lead to effective advancements in therapeutic strategies within modern medicine.

Sustainable synthesis of benzimidazole-based Schiff base using reusable CaAl2O4 nanophosphors catalyst: Insights into metal(II) complexes and DNA interactions

This article presents a new and facile method for the synthesis of Schiff base compounds with a benzimidazole group using a low-cost and reusable calcium aluminate nanophosphorus catalyst (CaAl2O4). This approach avoids harmful solvents and reactants, supporting a more environmentally friendly synthesis process. The catalyst maintained its activity and heterogeneity over four cycles with minimal loss of efficiency. The synthesis process was straightforward and eliminated the need for column chromatography. The Schiff base ligand (HL=(E)-N-((6-(thiophen-2-yl)pyridin-2-yl)methylene)-1H-benzo[d]imidazol-2-amine)) was synthesized by the reaction of 6-(thiophen-2-yl)pyridine-2-carbaldehyde with 1H-benzimidazole-2-amine. Subsequently, metal(II) complexes of Co(II), Ni(II), and Cu(II) were prepared using this ligand. Structural analysis of both the ligand and its metal complexes was carried out using various physicochemical and spectroscopic methods. Ni(II) and Co(II) complexes were found to adopt an octahedral geometry, while the Cu(II) complex exhibited a square-planar structure. Binding studies with calf thymus DNA (CT-DNA) at pH 7.2 were performed using UV-visible spectroscopy, viscosity measurements, and thermal denaturation studies and showed that the metal complexes intercalate into the DNA and produced a distinct binding pattern. Molecular docking simulations with AutoDock Vina provided insights into the interaction of these complexes with the B-DNA dodecamer. Furthermore, the ligand and its metal complexes showed UV-visible photonuclease activity against pUC19 DNA. Agarose gel electrophoresis showed that the metal complexes exhibit photoinduced nuclease activity, confirming their ability to cleave DNA upon exposure to light.

[rac-1,8-Bis(2-carbamoyleth-yl)-5,5,7,12,12,14-hexa-methyl-1,4,8,11-tetra-aza-cyclo-tetra-deca-ne]copper(II) di-acetate tetra-hydrate: crystal structure and Hirshfeld surface analysis

The title CuII macrocyclic complex salt tetra-hydrate, [Cu(C22H46N6O2)](C2H3O2)2·4H2O, sees the metal atom located on a centre of inversion and coordinated within a 4 + 2 (N4O2) tetra-gonally distorted coordination geometry; the N atoms are derived from the macrocycle and the O atoms from weakly associated [3.2048 (15) Å] acetate anions. Further stability to the three-ion aggregate is provided by intra-molecular amine-N-H⋯O(carboxyl-ate) hydrogen bonds. Hydrogen bonding is also prominent in the mol-ecular packing with amide-N-H⋯O(amide) inter-actions, leading to eight-membered {⋯HNCO}2 synthons, amide-N-H⋯O(water), water-O-H⋯O(carboxyl-ate) and water-O-H⋯O(water) hydrogen bonds featuring within the three-dimensional architecture. The calculated Hirshfeld surfaces for the individual components of the asymmetric unit differentiate the water mol-ecules owing to their distinctive supra-molecular association. For each of the anion and cation, H⋯H contacts predominate (50.7 and 65.2%, respectively) followed by H⋯O/O⋯H contacts (44.5 and 29.9%, respectively).

Redetermination of the crystal structure of (2E,4Z,13E,15Z)-3,5,14,16-tetramethyl-2,6,13,17-tetraazatricyclo[16.4.0.07,12]docosa-1(22),2,4,7,9,11,13,15,18,20-decaene, C22H24N4

C22H24N4, triclinic, P 1 ‾ $P‾{1}$ (no. 2), a = 9.217(4) Å, b = 9.774(4) Å, c = 10.843(4) Å, α = 96.770(2)°, β = 101.791(5)°, γ = 105.873(3)°, V = 903.9(6) Å3, Z = 2, R gt (F) = 0.0391, wR ref (F 2) = 0.1069, T = 93(2) K.

Design, synthesis, in vitro anticancer, antioxidant and antibacterial activity; DNA/BSA binding, photoleavage and docking studies of Cu(II) ternary metal complexes

Three mononuclear, mixed ligand ternary Cu(II) complexes of 3-((Z)-1-(2-hydroxyphenylimino)ethyl)-4-hydroxy-6-methyl-2H-pyran-2-one (HEHMP) viz; [Cu-(Phen) (HEHMP)] (1a), [Cu-(Bpy)(HEHMP)] (1 b) and [Cu-Bpy(NCS)(HEHMP)] (1c) were synthesized and characterized by data obtained from various spectral techniques. The binding affinities of these complexes with calf thymus DNA (CT-DNA) and bovine serum albumin (BSA) protein were explored by absorption and fluorescence quenching titrations. The results indicated strong affinity of the title compounds to bind with both CT-DNA and BSA. The antioxidant properties of the synthesized compounds evaluated by free-radical scavenging method using spectrophotometric technique indicated their affirmative potential activity. Gel electrophoresis experiments revealed the efficacy of metal complexes in resulting the cleavage of pBR322 supercoiled DNA. In vitro cytotoxicity studies of these complexes evaluated by 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay against HeLa and MCF-7 cancer cell lines indicated relatively high effectiveness of the complex 1c. Confocal microscopy signified the potential of the complexes to induce apoptosis in HeLa cell lines. In addition, the antibacterial activity of the compounds carried out by disc diffusion method revealed significantly enhanced antibacterial activity in Cu (II) ternary complexes compared to the activity of ligands in unbound form signifying the implicit role of metal ion in inducing lipophilic character.

Molecular encapsulation of berberine by a modified β-cyclodextrin and binding of host: guest complex to G-quadruplex DNA

The capacity to control quadruplex formation, especially in cancer cells, is captivating and entails a reasonable comprehension of the ligand-G-quadruplex binding. Herein, we report an iminopyrenyl-β-cyclodextrin conjugate interacting with duplex and G-quadrulex DNAs. In addition, the host: guest association of the established G-quadruplex binder, berberine, with the β-cyclodextrin derivative is studied employing 2-D ROESY. NMR, UV-visible, and fluorescence spectroscopic techniques are utilized to explore the β-cyclodextrin conjugate's interaction with the quadruplexes. The Binding constants are accounted for the association of the ligands to each of the DNAs viz., calf thymus DNA (duplex), kit22, telo24, and myc22 (quadruplexes). The modulation of the iminopyrenyl-β-cyclodextrin binding to the DNAs are observed when berberine is loaded in the host molecule. A vivid distinction between the interactions of the ligands with duplex and quadruplex structures is inferred. Berberine-loaded iminopyrenyl-β-cyclodextrin shows a higher affinity for binding to kit22.