Pharmacological Activities of Benzimidazole Derivatives

Benzimidazole, also known as 1H-benzimidazole and 1,3-benzodiazole, is fused by the benzene ring and the five-membered imidazole ring. Benzimidazole is an electron-rich aromatic heterocyclic compound containing two N atoms that can form complexes with metal ions containing empty orbitals. Because benzimidazole is similar in structure to natural purines, it is one of the most biologically active compounds among many active compounds. Among them, 2-arylbenzimidazoles can bind to different tyrosine kinases, which makes them attract extensive attention as anticancer drugs. The lone pair of electrons on the N of the imidazole ring can form coordination bonds with metal ions in the protein to bind with different enzymes and proteins, and prevent DNA transcription by inhibiting the action of related enzymes in the process of nucleic acid formation, resulting in cell death. As an important targeting pharmacophore, the high therapeutic potential of benzimidazole drugs has inspired medicinal chemists to explore the synthesis of novel chemotherapeutic agents containing benzimidazole moieties.

After years of research, benzimidazoles exhibit a variety of biological activities to make them an important heterocyclic system. As the basic skeleton of nitrogen-containing heterocycles, benzimidazole plays an important role in the discovery and design of lead drugs, including antiparasitic, antibacterial, antiviral, antifungal, anticonvulsant, antihypertensive drugs, antihistamines, analgesics, anti-inflammatory drugs, anticancer agents, anticoagulants and proton pump inhibitors, etc. In addition, because benzimidazole compounds have many excellent physical and chemical properties, they also widely exist in the main structure of optoelectronic materials, chemical sensors, and new curing agents for epoxy resins.

Antibacterial Activity

Antibacterial agents are mainly used to prevent the growth of microorganisms or to kill them. Generally, antibacterial drugs are divided into antifungals and antibiotics. Currently, studies have found that benzimidazoles can inhibit protein synthesis in microorganisms because benzimidazoles share structural similarities with purines. In addition, 2-substituted derivatives of benzimidazole are more effective in showing pharmacological activity. L Ravithej et al. used a simple and effective method to synthesize new coumarin-benzimidazole derivatives and evaluate the antibacterial activity of the synthesized compounds. They found that the coumarin-benzimidazole derivatives had better antibacterial activity against P.aeruginosa than the reference drugs ampicillin, tetracycline and kanamycin.

Antiviral Activity

The antiviral properties of benzimidazole derivatives have been tested against different virus strains, including human immunodeficiency virus (HIV), human cytomegalovirus (HCMV), enterovirus, respiratory syncytial virus, hepatitis B and C viruses (HBV and HCV), herpes simplex virus 1 (HSV-1) and bovine viral diarrhea virus (BVDV). For example, Xue et al. synthesized two different series of benzimidazole derivatives that showed potent enterovirus (Coxsackie) inhibition with IC50 values of 1.76 and 1.08 μg/ml, respectively.

Anti-inflammatory and Analgesic Activity

Benzimidazole-based compounds have important anti-inflammatory and analgesic activities. Benzimidazole compounds have the properties of inhibiting cyclooxygenase (COX), which is an enzyme involved in the biosynthesis of important inflammatory mediators called prostaglandins. Therefore, compounds derived from the benzimidazole moiety play an important role in the design and development of anti-inflammatory drugs. For example, Bukhari et al. reported the anti-inflammatory activity of a series of benzimidazole derivatives in 2016, in which compound A was found to be an effective inhibitor of 5-LOX, COX, TNF-α, IL-6 and cytokines in this series.

Anticancer Activity

Cancer is the second leading cause of death globally. As an anticancer drug, it should be toxic to cancer-affected cells rather than normal cells. Different benzimidazole derivatives play an important role in anticancer drugs discovered in recent years. Zhe et al. synthesized chrysin benzimidazole derivatives and studied their anticancer activity. The results showed that the synthesized compound had strong anti-proliferative activity against MFC cells with IC50 value of 25.72 ± 3.95 μM. Flow cytometry showed that benzimidazole derivatives increased MFC cell apoptosis in a dose-dependent manner. Furthermore, benzimidazole derivatives were observed to inhibit tumor growth in anticancer activity studies in tumor-bearing mice.

Antioxidant Activity

The ability of bioactive compounds to delay or prevent the oxidation of various substrates in organisms and foods is called antioxidant activity. Over the years, several benzimidazole derivatives have been explored for their ability to act as antioxidants. For example, Arora et al. evaluated the antioxidant properties of two benzimidazole compounds prepared by direct coupling of coumarin derivatives with benzimidazoles or by coupling through 2-position amide bonds. The benzimidazole compounds exhibited superior antioxidant activity compared to standard butylated hydroxytoluene.

Anticoagulants

Anticoagulants are used to prevent the formation of blood clots. Conditions and diseases such as heart attack, stroke, atrial fibrillation, pulmonary embolism, and deep vein thrombosis require anticoagulation therapy to reduce the risk of thrombosis. The anticoagulant activity of differently substituted benzimidazole derivatives has multiple potential uses in clinical practice. Thrombin (fIIa) is a multifunctional serine protease responsible for the proteolytic cleavage of fibrinogen. Thrombin inhibition is an important mechanism of coagulation inhibition. Studies have shown that benzimidazoles are suitable templates for placing various substituents required for interaction with thrombin. In addition, studies on the pharmacophore model of benzimidazole analogs suggest that benzimidazole derivatives have the potential to be developed as potent antithrombotic agents.

Antidiabetic Agents

Diabetes is a disease in which the body does not produce insulin or use insulin efficiently. Diabetes is also considered a leading cause of death and affects a large number of the world's population. Many natural and synthetic drugs have been developed to treat diabetes. Currently, a variety of benzimidazole-based compounds have shown promising antidiabetic activity by acting on targets at different stages of carbohydrate metabolism, some of which have been marketed for the treatment of type 2 diabetes.

Antihypertensive

Many marketed antihypertensive drugs contain benzimidazoles, and candesartan cilexetil and telmisartan are two prime examples. Specifically, they are angiotensin II receptor antagonists and play an important role in controlling hypertension. In recent years, many scientists have conducted research to prepare new benzimidazole antihypertensive drugs, which have similar or even better efficacy than traditional antihypertensive drugs. For example, Sharma et al. synthesized a series of substituted benzimidazole derivatives and assessed their properties as angiotensin II receptor antagonists or sartans using invasive (direct) methods in Wister rats. Compared to standard losartan, benzimidazole derivatives show outstanding antihypertensive properties.

Antiprotozoal Activity

Among the malaria parasites that cause human malaria, Plasmodium falciparum has begun to show resistance to existing antimalarial drugs, so there is an urgent need to develop drugs with new drug targets and new mechanisms of action. In recent years, several studies have shown that benzimidazole derivatives have antiparasitic, antimalarial and antiprotozoal activities against different species. Exploring the benzimidazole nucleus to discover new structural features required to optimize novel antiprotozoal agents is critical. In 2015, Keurulainen et al. synthesized several 2-arylbenzimidazole derivatives and announced their broad inhibitory effect on the sterile amastigotes of Leishmania donovani.

In addition to the above pharmacological activities, benzimidazole and its derivatives exhibit excellent antiulcer activity, antituberculosis activity, anticonvulsant activity, spasmolytic activity and antidepressant activity. Furthermore, the exploration of benzimidazole as a neuroprotective agent is also in progress. Click here to learn about our benzimidazole products.

Source: https://buildingblock.bocsci.com/resource/pharmacological-activities-of-benzimidazole-derivatives.html