Synthesis and biological evaluation of aminobenzimidazole derivatives with a phenylcyclohexyl acetic acid group as anti-obesity and anti-diabetic agents

A Comprehensive Account on Recent Progress in Pharmacological Activities of Benzimidazole Derivatives

Nowadays, nitrogenous heterocyclic molecules have attracted a great deal of interest among medicinal chemists. Among these potential heterocyclic drugs, benzimidazole scaffolds are considerably prevalent. Due to their isostructural pharmacophore of naturally occurring active biomolecules, benzimidazole derivatives have significant importance as chemotherapeutic agents in diverse clinical conditions. Researchers have synthesized plenty of benzimidazole derivatives in the last decades, amidst a large share of these compounds exerted excellent bioactivity against many ailments with outstanding bioavailability, safety, and stability profiles. In this comprehensive review, we have summarized the bioactivity of the benzimidazole derivatives reported in recent literature (2012-2021) with their available structure-activity relationship. Compounds bearing benzimidazole nucleus possess broad-spectrum pharmacological properties ranging from common antibacterial effects to the world's most virulent diseases. Several promising therapeutic candidates are undergoing human trials, and some of these are going to be approved for clinical use. However, notable challenges, such as drug resistance, costly and tedious synthetic methods, little structural information of receptors, lack of advanced software, and so on, are still viable to be overcome for further research.

Design, synthesis, kinetic, molecular dynamics, and hypoglycemic effect characterization of new and potential selective benzimidazole derivatives as Protein Tyrosine Phosphatase 1B inhibitors

Protein-tyrosine phosphatase 1B (PTP1B) is a negative regulator of insulin signaling pathway and has been validated as a therapeutic target for type 2 diabetes. A wide variety of scaffolds have been included in the structure of PTP1B inhibitors, one of them is the benzimidazole nucleus. Here, we report the design and synthesis of a new series of di- and tri- substituted benzimidazole derivatives including their kinetic and structural characterization as PTP1B inhibitors and hypoglycemic activity. Results show that compounds 43, 44, 45, and 46 are complete mixed type inhibitors with a Ki of 12.6 μM for the most potent (46). SAR type analysis indicates that a chloro substituent at position 6(5), a β-naphthyloxy at position 5(6), and a p-benzoic acid attached to the linker 2-thioacetamido at position 2 of the benzimidazole nucleus, was the best combination for PTP1B inhibition and hypoglycemic activity. In addition, molecular dynamics studies suggest that these compounds could be potential selective inhibitors from other PTPs such as its closest homologous TCPTP, SHP-1, SHP-2 and CDC25B. Therefore, the compounds reported here are good hits that provide structural, kinetic, and biological information that can be used to develop novel and selective PTP1B inhibitors based on benzimidazole scaffold.

Ethyl 1-Butyl-2-(2-hydroxy-4-methoxyphenyl)-1H-benzo[d]imidazole-5-carboxylate

Ethyl 4-(butylamino)-3-nitrobenzoate upon “one-pot” nitro-reductive cyclization using sodium dithionite and substituted aldehyde in dimethyl sulphoxide affords ethyl 1-butyl-2-(2-hydroxy-4-methoxyphenyl)-1H-benzo[d]imidazole-5-carboxylate in an 87% yield. The structural characterization was determined by Fourier-transfer infrared spectroscopy (FT-IR), Proton nuclear magnetic resonance (1H-NMR), Carbon-13 nuclear magnetic resonance (13C-NMR), mass spectrometry, Ultraviolet-visible(UV-Vis), photoluminescence (PL), thin-film solid emission spectra, cyclic voltammetry (CV) and thermogravimetric (TGA) analysis. Molecular electrostatic potential (MEP) was studied to determine the reactive sites of the molecule.

DGAT1 inhibitors protect pancreatic β-cells from palmitic acid-induced apoptosis

Previous studies demonstrated that prolonged exposure to elevated levels of free fatty acids (FFA), especially saturated fatty acids, could lead to pancreatic β-cell apoptosis, which plays an important role in the progression of type 2 diabetes (T2D). Diacylglycerol acyltransferase 1 (DGAT1), an enzyme that catalyzes the final step of triglyceride (TG) synthesis, has been reported as a novel target for the treatment of multiple metabolic diseases. In this study we evaluated the potential beneficial effects of DGAT1 inhibitors on pancreatic β-cells, and further verified their antidiabetic effects in db/db mice. We showed that DGAT1 inhibitors (4a and LCQ908) at the concentration of 1 μM significantly ameliorated palmitic acid (PA)-induced apoptosis in MIN6 pancreatic β-cells and primary cultured mouse islets; oral administration of a DGAT1 inhibitor (4a) (100 mg/kg) for 4 weeks significantly reduced the apoptosis of pancreatic islets in db/db mice. Meanwhile, 4a administration significantly decreased fasting blood glucose and TG levels, and improved glucose tolerance and insulin tolerance in db/db mice. Furthermore, we revealed that pretreatment with 4a (1 μM) significantly alleviated PA-induced intracellular lipid accumulation, endoplasmic reticulum (ER) stress, and proinflammatory responses in MIN6 cells, which might contribute to the protective effects of DGAT1 inhibitors on pancreatic β-cells. These findings provided a better understanding of the antidiabetic effects of DGAT1 inhibitors.

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.

Natural phenolic compounds potentiate hypoglycemia via inhibition of Dipeptidyl peptidase IV

Dipeptidyl peptidase IV (DPP IV) is a surface glycoprotein that can degrade glucagon like pepetide-1 (GLP-1) by decreasing blood sugar. Herbal medicines for diabetic therapy are widely used with acceptable efficacy but unsatisfied in advances. DPP IV was chosen as a template to employ molecular docking via Discovery Studio to search for natural phenolic compounds whether they have the inhibitory function of DPP IV. Then, docking candidates were validated and further performed signal pathway via Caco-2, C2C12, and AR42J cells. Lastly, a diet-induced diabetes in mice were applied to examine the efficacy and toxicity of hit natural phenolic products in long-term use (in vivo). After screening, curcumin, syringic acid, and resveratrol were found in high affinity with DPP IV enzymes. In enzymatic tests, curcumin and resveratrol showed potential inhibition of DPP IV. In vitro assays, curcumin inhibited of DPP IV activity in Caco-2 cells and ERK phosphorylation in C2C12 cells. Additionally, curcumin attenuated blood sugar in S961-treated C57BL/6 mice and in diet-induced diabetic ICR mice and long-term regulate HbA1c in diabetic mice. Curcumin targeted to DPP IV for reducing blood glucose, it possesses potential and alternative substitution of synthetic clinical drugs for the medication of diabetes.

Efficient Synthesis and in Silico Studies of the Benzimidazole Hybrid Scaffold with the Quinolinyloxadiazole Skeleton with Potential α-Glucosidase Inhibitory, Anticoagulant, and Antiplatelet Activities for Type-II Diabetes Mellitus Management and Treating Thrombotic Disorders

The current study evaluates antidiabetic, anticoagulant, and antiplatelet activity of novel benzimidazole-containing quinolinyl oxadiazoles. These derivatives are synthesized and characterized using spectroscopy (FT-IR, ¹H NMR, and mass spectroscopy) and single-crystal X-ray diffraction methods. The inhibitory effects of these compounds were evaluated by the α-glucosidase inhibitory assay and shows the activity in the range of IC₅₀ = 0.66 ± 0.05 to 3.79 ± 0.46 μg/mL. In addition, molecular docking studies revealed that benzimidazole-containing quinolinyl oxadiazoles can correctly dock into the target receptor protein of the human intestinal α-glucosidase, while their bioavailability/drug-likeness was predicted to be acceptable but requires further optimization. On the other hand, compound 8a and 8d showed anticoagulant activity as they enhanced the clotting time from control 180-410 and 180-390 s, respectively, in platelet rich plasma and 230-460 and 230-545 s in platelet poor plasma. Furthermore, only 8a showed antiplatelet activity by inhibiting epinephrine-induced platelet aggregation, and the observed aggregation inhibition was found to be 93.4%. Compounds 8a-f show nontoxic properties because of the non-hydrolyzing properties in the RBC cells. In addition, 8a and 8d show anti-edema and anti-hemorrhagic properties in the experimental mice. These findings reveal that benzimidazole-containing quinolinyl oxadiazoles act as α-glucosidase inhibitors to develop novel therapeutics for treating type-II diabetes mellitus and can act as lead molecules in drug discovery as potential antidiabetic and antithrombotic agents.

Synthesis and evaluation of antimicrobial, antitubercular and anticancer activities of 2-(1-benzoyl-1H-benzo[d]imidazol-2-ylthio)-N-substituted acetamides

BACKGROUND

The study describes the synthesis, characterization, in vitro antimicrobial and anticancer evaluation of a series of 2-(1-benzoyl-1H-benzo[d]imidazol-2-ylthio)-N-substituted acetamide derivatives. The synthesized derivatives were also assessed for in vitro antitubercular activity against Mycobacterium tuberculosis H37Rv. The compounds found active in in vitro study were assessed for their in vivo antitubercular activity in mice models and for their inhibitory action on vital mycobacterial enzymes viz, isocitrate lyase, pantothenate synthetase and chorismate mutase.

RESULTS

Compounds 8, 9 and 11 emerged out as excellent antimicrobial agents in antimicrobial assays when compared to standard antibacterial and antifungal drugs. The results of anticancer activity displayed that majority of the derivatives were less cytotoxic than standard drugs (tamoxifen and 5-fluorouracil) towards MCF7 and HCT116 cell lines. However, compound 2 (IC₅₀ = 0.0047 µM/ml) and compound 10 (IC₅₀ = 0.0058 µM/ml) showed highest cytotoxicity against MCF7 and HCT116 cell lines, respectively. The results of in vivo antitubercular activity revealed that a dose of 1.34 mg/kg was found to be safe for the synthesized compounds. The toxic dose of the compounds was 5.67 mg/kg while lethal dose varied from 1.81 to 3.17 mg/kg body weight of the mice. Compound 18 inhibited all the three mycobacterial enzymes to the highest level in comparison to the other synthesized derivatives but showed lesser inhibition as compared to streptomycin sulphate.

CONCLUSIONS

A further research on most active synthesized compounds as lead molecules may result in discovery of novel anticancer and antitubercular agents.

Species-Specific Inactivation of Triosephosphate Isomerase from Trypanosoma brucei: Kinetic and Molecular Dynamics Studies

Human African Trypanosomiasis (HAT), a disease that provokes 2184 new cases a year in Sub-Saharan Africa, is caused by Trypanosoma brucei. Current treatments are limited, highly toxic, and parasite strains resistant to them are emerging. Therefore, there is an urgency to find new drugs against HAT. In this context, T. brucei depends on glycolysis as the unique source for ATP supply; therefore, the enzyme triosephosphate isomerase (TIM) is an attractive target for drug design. In the present work, three new benzimidazole derivatives were found as TbTIM inactivators (compounds 1, 2 and 3) with an I₅₀ value of 84, 82 and 73 µM, respectively. Kinetic analyses indicated that the three molecules were selective when tested against human TIM (HsTIM) activity. Additionally, to study their binding mode in TbTIM, we performed a 100 ns molecular dynamics simulation of TbTIM-inactivator complexes. Simulations showed that the binding of compounds disturbs the structure of the protein, affecting the conformations of important domains such as loop 6 and loop 8. In addition, the physicochemical and drug-like parameters showed by the three compounds suggest a good oral absorption. In conclusion, these molecules will serve as a guide to design more potent inactivators that could be used to obtain new drugs against HAT.

Therapeutic evolution of benzimidazole derivatives in the last quinquennial period

Benzimidazole, a fused heterocycle bearing benzene and imidazole has gained considerable attention in the field of contemporary medicinal chemistry. The moiety is of substantial importance because of its wide array of pharmacological activities. This nitrogen containing heterocycle is a part of a number of therapeutically used agents. Moreover, a number of patents concerning this moiety in the last few years further highlight its worth. The present review covers the recent work published by scientists across the globe during last five years.

Functionalized Benzimidazole Scaffolds: Privileged Heterocycle for Drug Design in Therapeutic Medicine

Benzimidazole derivatives are crucial structural scaffolds found in diverse libraries of biologically active compounds which are therapeutically useful agents in drug discovery and medicinal research. They are structural isosteres of naturally occurring nucleotides, which allows them to interact with the biopolymers of living systems. Hence, there is a need to couple the latest information with the earlier documentations to understand the current status of the benzimidazole nucleus in medicinal chemistry research. This present work unveils the benzimidazole core as a multifunctional nucleus that serves as a resourceful tool of information for synthetic modifications of old existing candidates in order to tackle drug resistance bottlenecks in therapeutic medicine. This manuscript deals with the recent advances in the synthesis of benzimidazole derivatives, the widespread biological activities as well as pharmacokinetic reports. These present them as a toolbox for fighting infectious diseases and also make them excellent candidates for future drug design.

High Throughput Screening Identifies a Novel Compound Protecting Cardiomyocytes from Doxorubicin-Induced Damage

Antracyclines are effective antitumor agents. One of the most commonly used antracyclines is doxorubicin, which can be successfully used to treat a diverse spectrum of tumors. Application of these drugs is limited by their cardiotoxic effect, which is determined by a lifetime cumulative dose. We set out to identify by high throughput screening cardioprotective compounds protecting cardiomyocytes from doxorubicin-induced injury. Ten thousand compounds of ChemBridge's DIVERSet compound library were screened to identify compounds that can protect H9C2 rat cardiomyocytes against doxorubicin-induced cell death. The most effective compound proved protective in doxorubicin-treated primary rat cardiomyocytes and was further characterized to demonstrate that it significantly decreased doxorubicin-induced apoptotic and necrotic cell death and inhibited doxorubicin-induced activation of JNK MAP kinase without having considerable radical scavenging effect or interfering with the antitumor effect of doxorubicin. In fact the compound identified as 3-[2-(4-ethylphenyl)-2-oxoethyl]-1,2-dimethyl-1H-3,1-benzimidazol-3-ium bromide was toxic to all tumor cell lines tested even without doxorubicine treatment. This benzimidazole compound may lead, through further optimalization, to the development of a drug candidate protecting the heart from doxorubicin-induced injury.

Comprehensive Review in Current Developments of Benzimidazole-Based Medicinal Chemistry

The properties of benzimidazole and its derivatives have been studied over more than one hundred years. Benzimidazole derivatives are useful intermediates/subunits for the development of molecules of pharmaceutical or biological interest. Substituted benzimidazole derivatives have found applications in diverse therapeutic areas such as antiulcer, anticancer agents, and anthelmintic species to name just a few. This work systematically gives a comprehensive review in current developments of benzimidazole-based compounds in the whole range of medicinal chemistry as anticancer, antibacterial, antifungal, anti-inflammatory, analgesic agents, anti-HIV, antioxidant, anticonvulsant, antitubercular, antidiabetic, antileishmanial, antihistaminic, antimalarial agents, and other medicinal agents. This review will further be helpful for the researcher on the basis of substitution pattern around the nucleus with an aim to help medicinal chemists for developing an SAR on benzimidazole drugs/compounds.

Structure activity relationship (SAR) study of benzimidazole scaffold for different biological activities: A mini-review

Benzimidazoles are the fused heterocyclic ring systems which form an integral part of vitamin B12 and have been luring many researchers all over the world to assess their potential therapeutic significance. They are known for their crucial role in numerous diseases via various mechanisms. Substitution of benzimidazole nucleus is a crucial step in the drug discovery process. Therefore, it is necessary to gather the latest information along with the earlier information to understand the present status of benzimidazole nucleus in drug discovery. In the present review, benzimidazole derivatives with different pharmacological activities are described on the basis of SAR study using structural substitution pattern around the benzimidazole nucleus and aims to review the reported work related to the chemistry and pharmacological activities of benzimidazole derivatives during recent years. The present manuscript to the best of our knowledge is the first compilation on synthesis and medicinal aspects including structure-activity relationships of benzimidazole reported to date.

Preclinical pharmacokinetic characterization of 2-(4-(4-(5-(2-phenyl-5-(trifluoromethyl)oxazole-4-carboxamido)-1H-benzo[d]imidazol-2-yl)phenyl)cyclohexyl) acetic acid, a novel DGAT-1 inhibitor

1. A novel diacylglyceride acyltransferase-1 (DGAT-1) inhibitor, 2-(4-(4-(5-(2-phenyl-5-(trifluoromethyl) oxazole-4-carboxamido)-1H-benzo[d]imidazol-2-yl)phenyl)cyclohexyl) acetic acid (KR-69232), was synthesized for a potential therapeutic use against several metabolic disorders, such as obesity, insulin resistance, and type II diabetes, characterized by excessive triglycerides (TGs) in the blood. 2. The half-lives against phase I metabolism were measured as 75.3 ± 20.9 min and over 120 min in rat and human liver microsomes, respectively. In Caco-2 cell monolayers, extremely low permeability (<0.13 × 10⁻⁶cm/s) was seen in the absorptive direction, predicting limited intestinal absorption of KR-69232. This compound was highly bound to rat and human plasma proteins (>99.8%). 3. With the intravenous administration of KR-69232 in rats (1, 2, and 5 mg/kg), non-linear kinetics were observed at the highest dose, with significantly higher systemic clearance, higher volume of distribution, and lower dose-normalized AUC. Following oral administration, it exhibited low bioavailability (<10%) and was absorbed slowly (T(max), 3.8-5.2 h) over the dose range. We also confirmed that considerable KR-69232 remained in the intestine at T(max), demonstrating its limited absorption into the systemic circulation.

Determination of a novel diacylglycerol acyltransferase 1 inhibitor, 2-[4-(4-{5-[2-phenyl-5-(trifluoromethyl) oxazole-4-carboxamido]-1H-benzo[d]imidazol-2-yl} phenyl) cyclohexyl] acetic acid (KR-69232) in rat plasma using liquid chromatography-tandem mass spectrometry and its application to a pharmacokinetic study

A liquid chromatography-tandem mass spectrometry method was developed and validated for the quantification of KR-69232, a diacyltransferase 1 inhibitor, in rat plasma. KR-69232 in the concentration range of 0.004-4 µg/mL was linear. The intra-and inter-day precision and accuracy were acceptable (<20%). KR-69232 was stable under various storage and handling conditions. The method was applied successfully in a pharmacokinetic study of KR-69232 in rats.