A Critical Review on Therapeutic Potential of Benzimidazole Derivatives: A Privileged Scaffold.

Benzimidazole nucleus is a predominant heterocycle displaying a wide spectrum of pharmacological activities. The privileged nature of the benzimidazole scaffold has been revealed by its presence in most small molecule drugs and in its ability to bind multiple receptors with high affinity. A literature review of the scaffold reveals several instances where structural modifications of the benzimidazole core have resulted in high-affinity lead compounds against a variety of biological targets. Hence, this structural moiety offers opportunities to discover novel, better, safe and highly potent biological agents. The goal of the present review is to compile the medicinal properties of benzimidazole derivatives with a focus on SAR (Structure-Activity Relationships).

Design, Synthesis, and Pharmacological Evaluation of Novel Tacrine Derivatives as Multi-target ANTI-Alzheimer's Agents In Rat Models.

BACKGROUND: Alzheimer's disease is a progressive neurodegenerative disorder for which no curative drugs are available and treatment available is just palliative. OBJECTIVES: Current research focused on design of Tacrine-Flavone hybrids as multitargeted cholinesterase and monoamine oxidase B inhibitors. METHODS: A total of 10 Tacrine- Flavone hybrids were designed, synthesized and characterized. The in vitro neurotoxicity and hepatotoxicity of the synthesized compounds determined using SHSY5Y cell line and HEPG2 cell line. One most active compound (AF1) with least toxicity in in vitro studies was chosen for in vivo studies. Acute and subacute toxicity of the novel compound AF1 conducted on Wistar rats according to OECD guideline 423 and 407. The LD50 value of the novel compound calculated according to Finney's method using Probit analysis. Anti-Alzheimer's activity studies conducted on male Wistar rats. Behavioral studies conducted and AChE and MAO-B activity determined in rat brain. RESULTS AND DISCUSSION: All the compounds exhibited good inhibitory effect on MAO B and AChE. The neurotoxicity studies of the active compound AF1 did not show toxicity up to 100µg. The hepatotoxicity study of the most active compound AF1, showed the compound to be safe up to 200µg. The LD 50 value of the novel compound after a single oral administration was found to be 64 mg/kg bodyweight in rats. Subacute toxicity studies did not show any remarkable toxicity in the vital organs up to 40 mg/kg. Activity studies showed comparable results with standard at 20 mg/kg. CONCLUSION: The results showed that the novel Tacrine-Flavone hybrids are multitarget-directed ligands, which are safe and active compared to tacrine and can be a promising lead molecule for further study.

Design Synthesis and in vitro Evaluation of Tacrine-flavone Hybrids as Multifunctional Cholinesterase Inhibitors for Alzheimer's Disease.

BACKGROUND: Alzheimer's disease (AD) is a multifactorial neurodegenerative disorder. The multifactorial etiology of AD has led to the design of multitarget directed ligands (MTDL) for AD. Tacrine an acetylcholinesterase (AChE) inhibitor was the first FDA approved drug for AD but is discontinued due to hepatotoxicity. OBJECTIVE: Present research focused on incorporating a flavone to the tacrine nucleus to enhance the anti-Alzheimer's property of the tacrine with the synergistic effect of flavone which is a very good antioxidant. It is expected that the antioxidant property and hepatoprotective nature of flavones will reduce the hepatotoxic side effect of tacrine. METHODS: We designed and synthesized ten flavone substituted tacrine derivatives and evaluated for in vitro AChE and BuChE inhibitoy activity by modified Ellman's method using eeAChE and eqBuChE. In vitro antioxidant activity was studied by DPPH radical scavenging assay. Molecular modeling studies were conducted in Schrodinger and AutoDock Vina with TcAChE(PDB ID:1H23),hAChE(PDB ID:4EY7) and hBuChE(PDB ID:4TPK). RESULTS: All the compounds exhibited potent inhibitory effect on AChE and BuChE with IC50 values in µM concentration. The compounds exhibited very good antioxidant activity in DPPH radical scavenging assay. Among the compounds the compound AF1 showed highest activity with IC50 value of 0.93 µM for AChE and 1.48 µM for BuChE and also showed significant antioxidant activity (2.6 nM). A correlation graph was plotted for IC 50 values vs Dock score and the results are promising with r2 values of 0.62 and 0.73 for AChE and BuChE inhibition respectively which proved the reliability of docking approaches. CONCLUSION: The results highlighted the multifunctional nature of the novel Tacrine-Flavone hybrids and they may be promising MTDL for AD.

Design, Synthesis, Docking and Biological Evaluation of Novel 4-hydroxy Coumarin Derivatives.

BACKGROUND: Hospital-acquired (HA) infections are caused due to E. coli, which is resistant to multiple drugs particularly to fluoroquinolone class of drugs. Urinary tract infections (UTI) affects people in the community and hospitals. 150 million people per annum are suffering from UTI worldwide. METHODS: In this present study, we designed 36 novel coumarin derivatives, also we predicted pharmacokinetic and toxicity parameters. Docking studies were also carried out and all the compounds were evaluated for antibacterial activity against resistant quinolone E. coli strain ATCC 25922. It was interesting to note that the introduction of electron-withdrawing group on the aromatic ring resulted in compounds with an increased antibacterial activity, which is observed in compound 6 (with 4-nitro substitution), compound 23 (chloro) and compound 30 (chloro, nitro). RESULTS: From the MIC results, it was observed that compounds 6, 23 and 30 showed higher activity with 0.5µg/ml, 0. 12 µg/ml, 0.5 µg/ml respectively. Docking studies were performed with the active site of DNA gyrase (PDB ID: 4CKK). The maximum binding energy was found to be -10.7 Kcal/mol. CONCLUSION: From the study, it was found that 3 compounds were potentially active against quinolone- resistant E. coli strains. This study can further be extended for in vivo evaluation.

A Comprehensive Review on DNA Gyrase Inhibitors.

The newly emerging infectious organisms, the global crisis in antibiotic resistance, and the threat of bioterrorism create an urgent need to discover novel antimicrobial agents. In order to develop novel antimicrobial agents, the mechanism of infectious disease must be better understood. DNA Gyrase is a bacterial enzyme that plays an important role in the replication of DNA and transcription process. It is not present in higher eukaryotes making it a perfect target for developing new antibacterial agents. This review describes the role of DNA gyrase inhibitors in preventing various diseases. In this review, we outline the synthesis and pharmacological action of various novel DNA gyrase inhibitors. DNA gyrase inhibitors were used to treat tuberculosis, bacterial, fungal infections and malaria. DNA gyrase inhibitors mainly act by preventing the supercoiling of DNA strands..