Metal complexes of benzimidazole-derived as potential anti-cancer agents: synthesis, characterization, combined experimental and computational studies

Synthesis and antitumor activity of copper(II) complexes of imidazole derivatives

Complexes [Cu(PI)2(H2O)](NO3)2 (1), [Cu(PBI)2(NO3)]NO3 (2), [Cu(TBI)2(NO3)]NO3 (3), [Cu(BBIP)2](ClO4)2 (4) and [Cu(BBIP)(CH3OH)(ClO4)2] (5) were synthesized from the reactions of Cu(II) salts with 2-(2'-pyridyl)imidazole (PI), (2-(2'-pyridyl)benzimidazole (PBI), 2-(4'-thiazolyl)-benzimidazole (TBI), 2,6-bis(benzimidazol-2-yl)-pyridine (BBIP), respectively. Their compositions and crystal structures were determined. Their in-vitro antitumor activities were screened on four cancer cell lines and one normal cell line (HL-7702) using cisplatin as the positive control. Complexes 2 and 4 show higher cytotoxicity than the other three complexes. The cytotoxicity of complex 2 are comparable to those for cisplatin, and the cytotoxicity for 4 are much higher than those for cisplatin. From a viewpoint of antitumor, 2 might be a nice choice on the tumor cell line of T24 because its IC50 values on T24 and HL-7702 are 15.03 ± 1.10 and 21.34 ± 0.35, respectively. Thus, a mechanistic study for complexes 2 and 4 on T24 cells was conducted. It revealed that they can reduce mitochondrial membrane potential and increase mitochondrial membrane permeability, resulting in increased intracellular ROS levels, Ca2+ inward flow, dysfunctional mitochondria and the eventual cell apoptosis. In conclusion, they can induce cell apoptosis through mitochondrial dysfunction. These findings could be useful in the development of new antitumor agents.

Structurally diverse zinc(II) complexes containing tripodal tetradentate phenoxido-amines with promising antiproliferative effects

Structurally diverse zinc(II) complexes with tripodal tetradentate phenolic-amines of variable substituents in the phenol and amine moieties were synthesized and thoroughly characterized. The two dinuclear [Zn2(L1)2](ClO4)2·MeOH (1), [Zn2(L2)2](ClO4)2 (2), and four mononuclear [Zn(L3)(H2O)]·MeOH (3), [Zn(L4)] (4), [Zn(L5)] (5) and [Zn(L6)] (6) complexes revealed distorted octahedral, trigonal-bipyramidal or tetrahedral geometries. The free HL1 and H2L3-6 ligands, and complexes 1-6 were evaluated for in vitro cytotoxicity against human cancer cell lines (A2780, A2780R, PC-3 and 22Rv1) and normal healthy MRC-5 cells. Overall results revealed high-to-moderate cytotoxicity (with the best IC50 values for complex 6 ranging from 2.4 to 4.5 μM), which is however, significantly higher than that of the reference drug cisplatin. The moderately active complexes 1-4 showed considerable selectivity on A2780 cells (IC50 ≈ 16.3-19.5 μM) over MRC-5 ones (with IC50 >50 μM for 1, 2 and 4, and with IC50 >25 μM for 3). The complexes 1, 2, and 6 and the ligand H2L6 were chosen for subsequent deeper biological evaluations. Their time-resolved cellular uptake and other cellular effects in A2780 cells were studied, such as cell cycle profile, intracellular ROS production, induction of apoptosis and activation of caspases 3/7. Complexes 1 and 2 caused significant G0/G1 cell cycle arrest in A2780 cells and antioxidant effects at normal conditions. They showed only limited effects on cellular processes connected with cytotoxicity, i.e. induction of apoptosis, depletion of mitochondrial membrane potential, and autophagy. These findings can be at least partly attributed to the low ability of the complexes to enter the A2780 cells and the depression of metabolic activity of the target cancer cells.

Benzimidazole derivatives as a new scaffold of anticancer agents: Synthesis, optical properties, crystal structure and DFT calculations

The absolute necessity to fight some class of tumour is perceived as serious health concerns, and the discovery and development of effective anticancer agents are urgently needed. So, the novel benzimidazole derivatives (2a-b) were designed, synthesized, with their structures rigorously characterized using single X-ray crystallography, FT-IR, UV, and NMR spectroscopy, alongside elemental analysis. The geometric structures were optimized using density functional theory (DFT) calculations performed at the ωB97X-D/cc-pVDZ level, yielding good agreement with experimental XRD data. The studied salt complexes exhibited the ability to absorb UV light at 275 nm. Furthermore, anticancer activity of the compounds was screened against (MDA-MB-231, MCF-7, HT-29 and healthy cell line (HF)) and revealed the remarkable efficacy of select newly synthesized Benzimidazole derivatives (2a-b). Compound 2a showed relative significant higher cytotoxicity (165.02) in MDA-MB-231 cancer cell line. This underscores their promising potential in therapeutic applications, affirming their role as valuable contenders in the pursuit of novel anticancer agents.

Two rhenium compounds with benzimidazole ligands: synthesis and DNA interactions

Two rhenium compounds: cis-tetrachlorotetrabenzimidazoldirhenium(iii) chloride - I and tetrabenzimidazoldioxorhenium(v) - II have been synthesized and characterized. X-ray data are presented for the new complex II. I and II show strong emission that has been used to investigate their interaction with several non-canonical DNA structures. Both compounds have a quenching effect on the fluorescence intensity upon addition of the investigated oligonucleotides; I was more selective for binding G4-than II. Association constant values obtained for I and II with G-quadruplexes reached 106 M-1, which suggests a strong interaction between both complexes and these sequences. FRET-melting assays show that I and II have a rather high level of stabilization of ckit1 and ckit2 quadruplexes. I is toxic against macrophages RAW267.7 only in high concentrations, while complex II shows no toxicity against these cells. I and II accumulate inside cells in different degrees. Molecular dynamic simulation studies have provided insights into the binding modes of II with ckit1 and ckit2 G-quadruplexes. The results obtained show the DNA binding activity of the rhenium complexes and their ability to be players in the anti-cancer fight since they can bind to non-canonical DNA forms in oncogene promoters, accumulate in some cancer cells, and influence the cancer cells microenvironment.

Spectroscopic, computational, cytotoxicity, and docking studies of 6-bromobenzimidazole as anti-breast cancer agent

6-Bromobenzimidazole (6BBZ) has been calculated in this study utilizing the 6-311++G(d,p) basis set and the Becke-3-Lee-Yang-Parr density functional approaches. The basic frequencies and geometric optimization are known. FTIR, FT-Raman, and UV-Vis spectra of the substance are compared between its computed and observed values. The energy gap between highest occupied molecular orbital-lowest unoccupied molecular orbital and molecule electrostatic potentials has been represented by charge density distributions that may be associated with the biological response. Time-dependent density functional theory calculations in the gas phase and dimethyl sulfoxide were carried out to ascertain the electronic properties and energy gap values using the same basis set. Molecular orbital contributions are investigated using the overlap population, partial, and total densities of states. Natural bond analysis was found to have strong electron delocalization by means of π(C4-C9) → π*(C5-C6), LP (N1) → π*(C7-C8), and LP(Br12) → π*(C5-C6) interactions. The Fukui function and Mulliken analysis have been explored on the atomic charges of the molecule. The nuclear magnetic resonance chemical shifts for 1 H and 13 C have been computed using the gauge-independent atomic orbital technique. With the highest binding affinity (-6.2 kcal mol-1 ) against estrogen sulfotransferase receptor (PDB ID: 1AQU) and low IC50 value of 17.23 μg/mL, 6BBZ demonstrated potent action against the MCF-7 breast cancer cell line. Studies on the antibacterial activity and ADMET prediction of the molecule have also been carried out.

Anticancer properties of complexes derived from bidentate ligands

Cancer is the abnormal division and multiplication of cells in an organ or tissue. It is the second leading cause of death globally. There are various types of cancer such as prostate, breast, colon, lung, stomach, liver, skin, and many others depending on the tissue or organ where the abnormal growth originates. Despite the huge investment in the development of anticancer agents, the transition of research to medications that improve substantially the treatment of cancer is less than 10%. Cisplatin and its analogs are ubiquitous metal-based anticancer agents notable for the treatment of various cancerous cells and tumors but unfortunately accompanied by large toxicities due to low selectivity between cancerous and normal cells. The improved toxicity profile of cisplatin analogs bearing bidentate ligands has motivated the synthesis of vast metal complexes of bidentate ligands. Complexes derived from bidentate ligands such as β-diketones, diolefins, benzimidazoles and dithiocarbamates have been reported to possess 20 to 15,600-fold better anticancer activity, when tested on cell lines, than some known antitumor drugs currently on the market, e.g. cisplatin, oxaliplatin, carboplatin, doxorubicin, and 5-fluorouracil. This work discusses the anticancer properties of various metal complexes derived from bidentate ligands, for possible application in chemotherapy. The results discussed were evaluated by the IC50 values as obtained from cell line tests on various metal-bidentate complexes. The structure-activity relationship study of the complexes discussed, revealed that hydrophobicity is a key factor that influences anticancer properties of molecules.

Anticancer Potential of Sulfonamide Moieties via In-Vitro and In-Silico Approaches: Comparative Investigations for Future Drug Development

Several kinds of anticancer drugs are presently commercially accessible, but low efficacy, solubility, and toxicity have reduced the overall therapeutic indices. Thus, the search for promising anticancer drugs continues. The interactions of numerous essential anticancer drugs with DNA are crucial to their biological functions. Here, the anticancer effects of N-ethyl toluene-4-sulphonamide (8a) and 2,5-Dichlorothiophene-3-sulphonamide (8b) on cell lines from breast and cervical cancer were investigated. The study also compared how these substances interacted with the hearing sperm DNA. The most promising anticancer drug was identified as 2,5-Dichlorothiophene-3-sulfonamide (8b), which showed GI₅₀ of 7.2 ± 1.12 µM, 4.62 ± 0.13 µM and 7.13 ± 0.13 µM against HeLa, MDA-MB231 and MCF-7 cells, respectively. Moreover, it also exhibited significant electrostatic and non-electrostatic contributions to the binding free energy. The work utilized computational techniques, such as molecular docking and molecular dynamic (MD) simulations, to demonstrate the strong cytotoxicity of 2,5-Dichlorothiophene-3-sulfamide (8b) in comparison to standard Doxorubicin and cisplatin, respectively. Molecular docking experiments provided additional support for a role for the minor groove in the binding of the 2,5-Dichlorothiophene-3-sulfamide (8b)-DNA complex. The molecular docking studies and MD simulation showed that both compounds revealed comparable inhibitory potential against standard Doxorubicin and cisplatin. This study has the potential to lead to the discovery of new bioactive compounds for use in cancer treatment, including metallic and non-metallic derivatives of 2,5-Dichlorothiophene-3-sulfonamide (8b). It also emphasizes the worth of computational approaches in the development of new drugs and lays the groundwork for future research.