Self-Assembled Molecular Complexes of 1,10-Phenanthroline and 2-Aminobenzimidazoles: Synthesis, Structure Investigations, and Cytotoxic Properties

Three new molecular complexes (phen)3(2-amino-Bz)2(H+)(BF4-)·3H2O 5, (phen)3(2-amino-5(6)-methyl-Bz)2(H+)(BF4-)·H2O 6, and (phen)(1-methyl-2-amino-Bz)(H+)(BF4-) 7, were prepared by self-assembly of 1,10-phenanthroline (phen) and various substituted 2-aminobenzimidazoles. Confirmation of their structures was established through spectroscopic methods and elemental analysis. The X-ray diffraction analysis revealed that the crystal structure of 7 is stabilized by the formation of hydrogen bonds and short contacts. In addition, the molecular geometry and electron structure of molecules 5 and 6 were theoretically evaluated using density functional theory (DFT) methods. According to the DFT B3LYP/6-311+G* calculations, the protonated benzimidazole (Bz) units act as NH hydrogen bond donors, binding two phenanthrolines and a BF4- ion. Non-protonated Bz unit form hydrogen bonds with the N-atoms of a third molecule phen. The molecular assembly is held together by π-π stacking between benzimidazole and phenanthroline rings, allowing for N-atoms to associate with water molecules. The complexes were tested in vitro for their tumor cell growth inhibitory effects on prostate (PC3), breast (MDA-MB-231 and MCF-7), and cervical (HeLa) cancer cell lines using MTT-dye reduction assay. The in vitro cytotoxicity analysis and spectrophotometric investigation in the presence of ct-DNA, showed that self-assembled molecules 5-7 are promising DNA-binding anticancer agents warranting further in-depth exploration.

Benzimidazoles Containing Piperazine Skeleton at C-2 Position as Promising Tubulin Modulators with Anthelmintic and Antineoplastic Activity

Benzimidazole anthelmintic drugs hold promise for repurposing as cancer treatments due to their interference with tubulin polymerization and depolymerization, manifesting anticancer properties. We explored the potential of benzimidazole compounds with a piperazine fragment at C-2 as tubulin-targeting agents. In particular, we assessed their anthelmintic activity against isolated Trichinella spiralis muscle larvae and their effects on glioblastoma (U-87 MG) and breast cancer (MDA-MB-231) cell lines. Compound 7c demonstrated exceptional anthelmintic efficacy, achieving a 92.7% reduction in parasite activity at 100 μg/mL after 48 hours. In vitro cytotoxicity analysis of MDA-MB 231 and U87 MG cell lines showed that derivatives 7b, 7d, and 7c displayed lower IC50 values compared to albendazole (ABZ), the control. These piperazine benzimidazoles effectively reduced cell migration in both cell lines, with compound 7c exhibiting the most significant reduction, making it a promising candidate for further study. The binding mode of the most promising compound 7c, was determined using the induced fit docking-molecular dynamics (IFD-MD) approach. Regular docking and IFD were also employed for comparison. The IFD-MD analysis revealed that 7c binds to tubulin in a unique binding cavity near that of ABZ, but the benzimidazole ring was fitted much deeper into the binding pocket. Finally, the absolute free energy of perturbation technique was applied to evaluate the 7c binding affinity, further confirming the observed binding mode.

Treatment of hepatic and pulmonary hydatidosis with albendazole and praziquantel

Conservative treatment of human hydatidosis (cystic echinococcosis) with albendazole has improved significantly the prognosis of the disease. But its therapeutic effectiveness is 30 - 70 %. There is some evidence that the effectiveness of albendazole can be enhanced by praziquantel but there is no strict recommendation for the use of praziquantel as part of long-term drug therapy for hydatidosis. The aim of the study was to evaluate the effectiveness of the combination of albendazole and praziquantel in patients with hepatic and/or pulmonary hydatidosis. A total of 20 patients (aged 12 - 70 years old) were included in the study for a 5-year period. Fourteen patients (70 %) were with hepatic hydatidosis, 4 (20 %) with pulmonary and 2 (10 %) with hepatic and pulmonary hydatidosis. They were treated with albendazole (15 mg/kg/day) and praziquantel (40 mg/kg/weekly) for 2 - 9 one-month courses. The result of the therapy was followed using imaging (abdominal ultrasound, lung radiography, computed tomography) and serology. Seventeen (85 %) out of 20 patients showed evidence of response on imaging defined as improvement or cure of hydatid cysts. Seven (35 %) of the patients with multiple cystic echinococcosis took praziquantel once a week for 6 months. Only 3 patients (15 %) with multiple hydatidosis (2 with liver and 1 with pulmonary hydatidosis) failed to respond to the therapy with both drugs. No side effects have been reported by the patients. The combination of albendazole and praziquantel seems to be an option to improve the therapeutic effectiveness of the conservative treatment of cystic echinococcosis.

Fused Triazinobenzimidazoles Bearing Heterocyclic Moiety: Synthesis, Structure Investigations, and In Silico and In Vitro Biological Activity

[1,3,5]Triazino[1,2-a]benzimidazole-2-amines bearing heterocyclic moiety in 4-position were synthesized. The compounds were characterized by elemental analysis, IR, ¹H-NMR, ¹³C-NMR, and HRMS spectroscopy. The molecular geometry and electron structure of these molecules were theoretically studied using density functional theory (DFT) methods. The molecular structure of the synthesized fused triazinobenzimidazole was confirmed to correspond to the 3,4-dihydrotriazinobenzimidazole structure through the analysis of spectroscopic NMR data and DFT calculations. The antinematodic activity was evaluated in vitro on isolated encapsulated muscle larvae (ML) of Trichinella spiralis. The results showed that the tested triazinobenzimidazoles exhibit significantly higher efficiency than the conventional drug used to treat trichinosis, albendazole, at a concentration of 50 μg/mL. The compound 3c substituted with a thiophen-2-yl moiety exhibited the highest anthelmintic activity, with a larvicidal effect of 58.41% at a concentration of 50 μg/mL after 24 h of incubation. Following closely behind, the pyrrole analog 3f demonstrated 49.90% effectiveness at the same concentration. The preliminary structure-anti-T. spiralis activity relationship (SAR) of the analogues in the series was discussed. The cytotoxicity of the benzimidazole derivatives against two normal fibroblast cells (3T3 and CCL-1) and two cancer human cell lines (MCF-7 breast cancer cells and chronic myeloid leukemia cells AR-230) was evaluated using the MTT-dye reduction assay. The screening results indicated that the compounds showed no cytotoxicity against the tested cell lines. An in silico study of the physicochemical and pharmacokinetic characteristics of the novel synthesized fused triazinobenzimidazoles showed that they were characterized by a significant degree of drug-likeness and optimal properties for anthelmintic agents.

Novel Fluorescent Benzimidazole-Hydrazone-Loaded Micellar Carriers for Controlled Release: Impact on Cell Toxicity, Nuclear and Microtubule Alterations in Breast Cancer Cells

Fluorescent micellar carriers with controlled release of a novel anticancer drug were developed to enable intracellular imaging and cancer treatment simultaneously. The nanosized fluorescent micellar systems were embedded with a novel anticancer drug via the self-assembling behavior of well-defined block copolymers based on amphiphilic poly(acrylic acid)-block-poly(n-butyl acrylate) (PAA-b-PnBA) copolymer obtained by Atom Transfer Radical Polymerization (ATRP) and hydrophobic anticancer benzimidazole-hydrazone drug (BzH). Through this method, well-defined nanosized fluorescent micelles were obtained consisting of a hydrophilic PAA shell and a hydrophobic PnBA core embedded with the BzH drug due to the hydrophobic interactions, thus reaching very high encapsulation efficiency. The size, morphology, and fluorescent properties of blank and drug-loaded micelles were investigated using dynamic light scattering (DLS), transmission electron microscopy (TEM), and fluorescent spectroscopy, respectively. Additionally, after 72 h of incubation, drug-loaded micelles released 3.25 μM of BzH, which was spectrophotometrically determined. The BzH drug-loaded micelles were found to exhibit enhanced antiproliferative and cytotoxic effects on MDA-MB-231 cells, with long-lasting effects on microtubule organization, with apoptotic alterations and preferential localization in the perinuclear space of cancer cells. In contrast, the antitumor effect of BzH alone or incorporated in micelles on non-cancerous cells MCF-10A was relatively weak.

Modulation Effect on Tubulin Polymerization, Cytotoxicity and Antioxidant Activity of 1H-Benzimidazole-2-Yl Hydrazones

1H-benzimidazol-2-yl hydrazones with varying hydroxy and methoxy phenyl moieties were designed. Their effect on tubulin polymerization was evaluated in vitro on porcine tubulin. The compounds elongated the nucleation phase and slowed down the tubulin polymerization comparably to nocodazole. The possible binding modes of the hydrazones with tubulin were explored by molecular docking at the colchicine binding site. The anticancer activity was evaluated against human malignant cell lines MCF-7 and AR-230, as well as against normal fibroblast cells 3T3 and CCL-1. The compounds demonstrated a marked antineoplastic activity in low micromolar concentrations in both screened in vitro tumor models. The most active were the trimethoxy substituted derivative 1i and the positional isomers 1j and 1k, containing hydroxy and methoxy substituents: they showed IC₅₀ similar to the reference podophyllotoxin in both tumor cell lines, accompanied with high selectivity towards the malignantly transformed cells. The compounds exerted moderate to high ability to scavenge peroxyl radicals and certain derivatives-1l containing metha-hydroxy and para-methoxy group, and 1b-e with di/trihydroxy phenyl moiety, revealed HORAC values high or comparable to those of well-known phenolic antioxidants. Thus the 1H-benisimidazol-2-yl hydrazones with hydroxy/methoxy phenyl fragments were recognized as new agents exhibiting promising combined antioxidant and antineoplastic action.

1H-benzimidazole-2-yl hydrazones as tubulin-targeting agents: Synthesis, structural characterization, anthelmintic activity and antiproliferative activity against MCF-7 breast carcinoma cells and molecular docking studies

In the present study, fifteen benzimidazolyl-2-hydrazones 7a-7o of fluoro-, hydroxy- and methoxy-substituted benzaldehydes and 1,3-benzodioxole-5-carbaldehyde were synthesized and their structure was identified by IR, NMR, and elemental analysis. The compounds 7j 2-(3-hydroxybenzylidene)-1-(5(6)-methyl-1H-benzimidazol-2-yl)hydrazone and 7i 2-(3-hydroxybenzylidene)-1-(1H-benzimidazol-2-yl)hydrazone have exerted the strongest anthelmintic activity (100% after 24 h incubation period at 37 °C) against isolated muscle larvae of Trichinella spiralis in an in vitro experiment. The in vitro cytotoxicity assay towards MCF-7 breast cancer cells and mouse embryo fibroblasts 3T3 showed that the studied benzimidazolyl-2-hydrazones exhibit low to moderate cytotoxic effects. The ability of the studied benzimidazolyl-2-hydrazones to modulate microtubule polymerization was confirmed and suggested that their anthelmintic action is mediated through inhibition of the tubulin polymerization likewise the other known benzimidazole anthelmitics. It was also shown that the four most promising benzimidazolyl-2-hydrazones do not affect significantly the AChE activity even at high tested concentration, thus indicating that they do not have the potential for neurotoxic effects. The binding mode of compounds 7j and 7n in the colchicine-binding site of tubulin were clarified by molecular docking simulations. Taken together, these results demonstrate that for the synthesized benzimidazole derivatives the anthelmintic activity against T. spiralis and the inhibition of tubulin polymerization are closely related.

Synthesis, antitrichinnellosis and antiprotozoal activity of some novel thieno[2,3-d]pyrimidin-4(3H)-ones containing benzimidazole ring

Some novel thieno[2,3-d]pyrimidin-4(3H)-ones containing benzimidazol-2-yl-thioethyl- and benzimidazol-2-yl-methanethioethyl moiety in second position of the pyrimidine ring were synthesized in order to determine their antitrichinellosis and antiprotozoal effects. The structures of the compounds were confirmed by IR, (1)H NMR and elemental analysis. The antiparasitic screening showed that the benzimidazole derivatives of thieno[2,3-d]pyrimidin-4(3H)-ones exhibited higher activity against Trichinella spiralis in vitro in comparison albendazole. The most active compound, 2-[2-(5-nitro-1H-benzimidazol-1-yl)ethyl]-5,6,7,8-tetrahydro[1]benzothieno[2,3-d]pyrimidin-4(3H)-one 22 revealed 95% activity at a dosage of 5 mg/kg mw after 24 h, while compounds 8 and 10 applied at the same dose showed efficacy of 90% after 48 h. The compound 2-{2-[(5(6)-nitro-1H-benzimidazol-2-yl)thio]ethyl}-5,6,7,8-tetrahydro[1]-benzothieno[2,3-d]pyrimidin-4(3H)-one 11 exhibited 90% efficacy after 24 h. The pharmaco-therapeutic study in vivo on invaded with Lamblia muris white mice showed 100% effectiveness of the compounds 8, 10, 11, 13-15 and 22, 23 after five-days-treatment course.

Multiple tandem mass spectrometry-based investigation of the behaviour of some thiazol-benzimidazolones and 2-benzimidazolylsulfanyl ethanones

The behaviour in electrospray conditions of a series of thiazol-benzimidazolones and 2- benzimidazolylsulphanyl ethanones has been studied by means of multiple tandem mass spectrometry experiments. Even though the experimental conditions were the same, different behaviour is observed for the two classes of compounds. In the case of thiazol-benzimidazolones, the formation of a protonated complex with CH3OH employed as solvent is observed, but in the case of 2-benzimidazolylsulphanyl ethanones the formation of MNa+ ions is privileged. This behaviour has been related to molecular structure. The collisionally-induced decompositions of MH+ ions have been rationalised in terms of the Stevenson-Audier and even-electron rules, as well as on the basis of proton affinity data. Thus, protonated thiazol-benzimidazolones undergo facile loss of CO and a series of different decomposition pathways involving cleavage of the thiazolone ring that reflect the structure of the neutral fragments. In contrast, the decompositions of the protonated 2-benzimidazolylsulphanyl ethanones are mainly related to the piperazine moiety, suggesting that the protonation takes place on this substructural unit.