Design, synthesis, and docking studies of novel benzimidazoles for the treatment of metabolic syndrome

Electrochemical Cyclization of o-Aminyl Azobenzenes: Roles of Aldehydes in N-N Bond Cleavage

Direct functionalization of azobenzenes provides an approach to obtaining valuable molecules in synthetic chemistry. However, an efficient method for the cleavage of the N═N bond of azobenzenes, which is a key process for this transformation, is still lacking. We herein disclose an electrochemical reduction-induced cyclization of azobenzenes with aldehydes via N═N bond cleavage. This electrochemical cyclization of azobenzenes proceeds well in the absence of any transition metals or external chemical oxidants, leading to the formation of N-protected benzimidazoles in moderate to good yields.

Environmentally benign synthesis of unsymmetrical ureas and their evaluation as potential HIV-1 protease inhibitors via a computational approach

The present work reports the cost-effective, high yielding and environmentally acceptable preparation of unsymmetrical ureas from thiocarbamate salts using sodium percarbonate as an oxidant. Efficacy of the unsymmetrical ureas as potential human immune deficiency virus (HIV-1) protease inhibitors has been evaluated via in silico approach. The results revealed interactions of the urea compounds at the active site of the enzyme with favorable binding affinities causing possible mutations hindering the functioning of the enzyme. Further computational assessment of IC50 using known references satisfactorily authenticated the inhibitory action of the selected compounds against HIV-1 protease. Added to the easy synthesis of the ureas following an environmentally benign protocol, this work may be a valuable addition to the ongoing search for drugs with better efficacy profiles and reduced toxicity against HIV.

Density functional theory calculations and molecular docking of 2-phenylbenzimidazoles with estrogen receptor for quantitative structure-activity relationship studies

Benzimidazole derivatives, especially 2-phenylbenzimidazole with various substituents on the C-5, C-2 and C-6 positions, are so important in pharmaceutical chemistry. Multiple linear regression was applied to predict the activity of 27 novel 2-phenylbenzimidazole derivatives as anticancer agents. At first, we made an effort to create a QSAR model for a selected series of novel 2-phenylbenzimidazole with density functional theory and molecular docking descriptors. Then, we tried to investigate the nature of the interactions between 2-phenylbenzimidazole derivatives and the estrogen receptor using the molecular docking method. Six descriptors of MATS4e, GATS5e, R6v, R1v+, dipole moment, and torsional free energy were selected for modelling. Due to docking results, increase in the binding energy, and decrease in the dipole moment could increase inhibitor activity.

Recent Advances in Therapeutic Applications of Bisbenzimidazoles

Nitrogen-containing heterocycles are one of the most common structural motifs in approximately 80% of the marketed drugs. Of these, benzimidazoles analogues are known to elicit a wide spectrum of pharmaceutical activities such as anticancer, antibacterial, antiparasitic, antiviral, antifungal as well as chemosensor effect. Based on the benzimidazole core fused heterocyclic compounds, crescent-shaped bisbenzimidazoles were developed which provided an early breakthrough in the sequence-specific DNA recognition. Over the years, a number of functional variations in the bisbenzimidazole core have led to the emergence of their unique properties and established them as versatile ligands against several classes of pathogens. The present review provides an overview of diverse pharmacological activities of the bisbenzimidazole analogues in the past decade with a brief account of its development through the years.

Synthesis and insight into the structure-activity relationships of 2-phenylbenzimidazoles as prospective anticancer agents

In order to explore and develop new anticancer agents, three series of 2-phenylbenzimidazoles, 15-46, were condensed under simple and mild conditions using sodium metabisulfite as an oxidation agent and another series, 47-55, were obtained via a reduction reaction using sodium borohydride. All the compounds synthesized were evaluated for their in vitro anticancer activities against three human cancer cell lines. The novel compound 38 was found to be the most potent multi cancer inhibitor against A549, MDA-MB-231, and PC3 cell lines (IC50 values 4.47, 4.68 and 5.50 μg mL-1, respectively). In addition, compound 40 exhibited the best IC50 value of 3.55 μg mL-1 against the MDA-MB-231 cell line. The results demonstrated that introducing a new substituent to compounds 37-55 could improve their antiproliferative activities.

Synthesis and evaluation of new designed multiple ligands directed towards both peroxisome proliferator-activated receptor-γ and angiotensin II type 1 receptor

Because of the complex biological networks, many pathologic disorders fail to be treated with a molecule directed towards a single target. Thus, combination therapies are often necessary, but they have many drawbacks. An alternative consists in building molecules intended to interact with multiple targets, called designed multiple ligands. We followed such a strategy in order to treat metabolic syndrome, by setting up molecules directed towards both type 1 angiotensin II (AT₁) receptor and peroxisome proliferator-activated receptor-γ (PPAR-γ). For this purpose, many molecules were prepared by merging both pharmacophores following three different strategies. Their ability to activate PPAR-γ and to block AT₁ receptors were evaluated in vitro. This strategy led to the preparation of many new PPAR-γ activating and AT₁ blocking molecules. Among them, some exhibited both activities, highlighting the convenience of this approach.

Molecular docking, 3D-QSAR and structural optimization on imidazo-pyridine derivatives dually targeting AT1 and PPARg

Telmisartan, a bifunctional agent of blood pressure lowering and glycemia reduction, was previously reported to antagonize angiotensin II type 1 (AT1) receptor and partially activate peroxisome proliferator-activated receptor γ (PPARγ) simultaneously. Through the modification to telmisartan, researchers designed and obtained imidazo-\pyridine derivatives with the IC₅₀s of 0.49∼94.1 nM against AT1 and EC₅₀s of 20∼3640 nM towards PPARγ partial activation. For minutely inquiring the interaction modes with the relevant receptor and analyzing the structure-activity relationships, molecular docking and 3D-QSAR (Quantitative structure-activity relationships) analysis of these imidazo-\pyridines on dual targets were conducted in this work. Docking approaches of these derivatives with both receptors provided explicit interaction behaviors and excellent matching degree with the binding pockets. The best CoMFA (Comparative Molecular Field Analysis) models exhibited predictive results of q²=0.553, r²=0.954, SEE=0.127, r²_pred=0.779 for AT1 and q²=0.503, r²=1.00, SEE=0.019, r²_pred=0.604 for PPARγ, respectively. The contour maps from the optimal model showed detailed information of structural features (steric and electrostatic fields) towards the biological activity. Combining the bioisosterism with the valuable information from above studies, we designed six molecules with better predicted activities towards AT1 and PPARγ partial activation. Overall, these results could be useful for designing potential dual AT1 antagonists and partial PPARγ agonists.

Evolution of a Polyene Cyclization Cascade for the Total Synthesis of (-)-Cyclosmenospongine

We report a full account on the development of a unique cationic polyene cyclization for the total synthesis of the tetracyclic meroterpenoid (-)-cyclosmenospongine. A highly convergent three-component coupling strategy enabled rapid access to individual cyclization precursors that were tested for their reactivity. The successful transformation generates three rings and sets four consecutive stereocenters in a single operation proceeding in a highly efficient manner to give exclusively the trans-decalin framework. In addition, we found that the enol ether geometry and the relative configuration of C3 and C8 are crucial for the success of the polyene cyclization.

Diversity oriented synthesis of benzimidazole-based biheterocyclic molecules by combinatorial approach: a critical review

Because of the wide ranging bioactivities associated with the benzimidazole nucleus, this review highlights the advances made in the synthesis of benzimidazole-based biheterocyclic molecules by combinatorial approaches.

Synthesis, biological evaluation and molecular modeling of 1H-benzo[d]imidazole derivatives as novel anti-tubulin polymerization agents

A series of novel compounds (8a–21b) were designed and synthesized based on 2-phenyl-1H-benzo[d]imidazole. Compound 18b showed the most potent in vitro growth inhibitory activity and significant tubulin polymerization inhibitory activity.

Discovery of novel indazole derivatives as dual angiotensin II antagonists and partial PPARγ agonists

Identification of indazole derivatives acting as dual angiotensin II type 1 (AT1) receptor antagonists and partial peroxisome proliferator-activated receptor-γ (PPARγ) agonists is described. Starting from Telmisartan, we previously described that indole derivatives were very potent partial PPARγ agonists with loss of AT1 receptor antagonist activity. Design, synthesis and evaluation of new central scaffolds led us to the discovery of pyrrazolopyridine then indazole derivatives provided novel series possessing the desired dual activity. Among the new compounds, 38 was identified as a potent AT1 receptor antagonist (IC50=0.006 μM) and partial PPARγ agonist (EC50=0.25 μM, 40% max) with good oral bioavailability in rat. The dual pharmacology of compound 38 was demonstrated in two preclinical models of hypertension (SHR) and insulin resistance (Zucker fa/fa rat).

Angiotensin II AT(1) receptor blockers as treatments for inflammatory brain disorders

The effects of brain AngII (angiotensin II) depend on AT(1) receptor (AngII type 1 receptor) stimulation and include regulation of cerebrovascular flow, autonomic and hormonal systems, stress, innate immune response and behaviour. Excessive brain AT(1) receptor activity associates with hypertension and heart failure, brain ischaemia, abnormal stress responses, blood-brain barrier breakdown and inflammation. These are risk factors leading to neuronal injury, the incidence and progression of neurodegerative, mood and traumatic brain disorders, and cognitive decline. In rodents, ARBs (AT(1) receptor blockers) ameliorate stress-induced disorders, anxiety and depression, protect cerebral blood flow during stroke, decrease brain inflammation and amyloid-β neurotoxicity and reduce traumatic brain injury. Direct anti-inflammatory protective effects, demonstrated in cultured microglia, cerebrovascular endothelial cells, neurons and human circulating monocytes, may result not only in AT(1) receptor blockade, but also from PPARγ (peroxisome-proliferator-activated receptor γ) stimulation. Controlled clinical studies indicate that ARBs protect cognition after stroke and during aging, and cohort analyses reveal that these compounds significantly reduce the incidence and progression of Alzheimer's disease. ARBs are commonly used for the therapy of hypertension, diabetes and stroke, but have not been studied in the context of neurodegenerative, mood or traumatic brain disorders, conditions lacking effective therapy. These compounds are well-tolerated pleiotropic neuroprotective agents with additional beneficial cardiovascular and metabolic profiles, and their use in central nervous system disorders offers a novel therapeutic approach of immediate translational value. ARBs should be tested for the prevention and therapy of neurodegenerative disorders, in particular Alzheimer's disease, affective disorders, such as co-morbid cardiovascular disease and depression, and traumatic brain injury.

Historical Strategies for Lead Generation

An increasing number of lead generation approaches are being applied to multi-target drug discovery (MTDD). Historically, focussed screening and a knowledge-based approach called framework combination have been most widely used – with varying degrees of success. More recently, alternative screening approaches such as HTS, fragment-based screening and in silico screening are being used alongside the traditional approaches in order to discover novel hits with attractive physicochemical and oral pharmacokinetic properties. Factors influencing the feasibility of discovering DMLs for particular combinations are discussed in this chapter. The role of natural products and the discovery of probes for chemical biology are also highlighted.