Systematic Review on 1,2,3-Oxadiazoles, 1,2,4-Oxadiazoles, and 1,2,5-Oxadiazoles in the Antimycobacterial Drug Discovery

Tuberculosis remains a leading global health threat, exacerbated by the emergence of multi-drug-resistant strains. The search for novel therapeutic agents is critical in addressing this challenge. This review systematically summarizes the potential of oxadiazole derivatives as promising candidates in antimycobacterial drug discovery. We focus on various classes of oxadiazoles, especially 1,2,3-oxadiazoles, 1,2,4-oxadiazoles, and 1,2,5-s in structure-activity relationship studies are discussed, emphasizing the mechanisms of antimycobacterial action. Additionally, the synergistic potential of 1,2,4-oxadiazoles in enhancing the efficacy of existing tuberculosis treatment with ethionamide is also discussed. By integrating insights from recent research, this review aims to provide a comprehensive overview of the role of oxadiazoles in the fight against tuberculosis, paving the way for future investigations and the development of effective therapeutic strategies.

Recent advancements in the quest of benzazoles as anti-Mycobacterium tuberculosis agents

Tuberculosis (TB) remains a global health challenge, claiming numerous lives each year, despite recent advancements in drug discovery and treatment strategies. Current TB treatment typically involves long-duration chemotherapy regimens that are often accompanied by adverse effects. The introduction of new anti-TB drugs, such as Bedaquiline, Delamanid, and Pretomanid, offers hope for more effective treatment, although challenges persist keeping the quest to find new anti-TB chemotypes an incessant exercise of medicinal chemists. Towards this initiative, the benzazoles continue to draw attention and have been recognised as new anti-TB scaffolds. Benzazole-containing compounds emerged as new chemotypes with potential to offer a versatile platform for new anti-TB drug design to generate new leads for further optimization. The elucidation of their chemical properties, biological effects, and potential mechanisms of action, would lead to identify innovative candidates for TB therapy. As medicinal chemists delve deeper into the SARs and mechanisms of action of benzazole derivatives, new opportunities for creating effective and safe anti-TB medications arise. This review highlights the potential impact of benzazole-based compounds on the search for new therapeutic agents against tuberculosis, emphasizing the importance of continued research and innovation in the field.

Benzimidazole-Oxadiazole Hybrids-Development in Medicinal Chemistry: An Overview

To increase the success rate of drug discovery, one practical strategy is to begin molecular hybridisation. The presence of two or more pharmacophores in a single unit leads to a pharmacological potency greater than the sum of each individual moiety's potency. Heterocyclic compounds are very widely distributed in nature and are essential for life activities. Benzimidazole and oxadiazole are privileged structures in medicinal chemistry and are widely used in drug discovery and development due to their vast biological properties. The drug-like properties (like pharmacokinetics and pharmacodynamics) of the individual scaffolds can be improved by benzimidazole-oxadiazole chimeric molecules via a molecular hybridisation approach. Benzimidazole and oxadiazole cores can either be fused or incorporated using either functional groups/bonds. Over the last few decades, drug discovery scientists have predicted that these moieties could be interconnected to yield a novel or modified hybrid compound. Benzimidazole and oxadiazole hybrids were identified as the most potent anticancer, antimicrobial, anti-inflammatory, antioxidant, anticonvulsant, antidepressant, antihypertensive and antitubercular agents. In this context, the present review describes the biological properties of benzimidazole-oxadiazole (1,3,4 and 1,2,4) hybrids, their possible structure-activity relationship and the mechanism of action studies presented. This review article is intended to stimulate fresh ideas in the search for rational designs of more active and less toxic benzimidazole-oxadiazole hybrid prospective therapeutic candidates, as well as more effective diagnostic agents and pathologic probes.

Exploration of Remarkably Potential Multitarget-Directed N-Alkylated-2-(substituted phenyl)-1H-benzimidazole Derivatives as Antiproliferative, Antifungal, and Antibacterial Agents

Improving lipophilicity for drugs to penetrate the lipid membrane and decreasing bacterial and fungal coinfections for patients with cancer pose challenges in the drug development process. Here, a series of new N-alkylated-2-(substituted phenyl)-1H-benzimidazole derivatives were synthesized and characterized by 1H and 13C NMR, FTIR, and HRMS spectrum analyses to address these difficulties. All the compounds were evaluated for their antiproliferative, antibacterial, and antifungal activities. Results indicated that compound 2g exhibited the best antiproliferative activity against the MDA-MB-231 cell line and also displayed significant inhibition at minimal inhibitory concentration (MIC) values of 8, 4, and 4 μg mL-1 against Streptococcus faecalis, Staphylococcus aureus, and methicillin-resistant Staphylococcus aureus compared with amikacin. The antifungal data of compounds 1b, 1c, 2e, and 2g revealed their moderate activities toward Candida albicans and Aspergillus niger, with MIC values of 64 μg mL-1 for both strains. Finally, the molecular docking study found that 2g interacted with crucial amino acids in the binding site of complex dihydrofolate reductase with nicotinamide adenine dinucleotide phosphate.

Electrochemical Synthesis of Benzo[d]imidazole via Intramolecular C(sp3)-H Amination

An electrochemical dehydrogenative amination for the synthesis of benzimidazoles was developed. This electrosynthesis method could address the limitations of the C(sp3)-H intramolecular amination synthesis reaction and provide novel access to obtain 1,2-disubstituted benzimidazoles without transition metals and oxidants. Under undivided electrolytic conditions, various benzimidazole derivatives could be synthesized, exhibiting functional group tolerance.

Biological activity of oxadiazole and thiadiazole derivatives

Abstract

The 5-membered oxadiazole and thiadiazole scaffolds are the most privileged and well-known heterocycles, being a common and essential feature of a variety of natural products and medicinal agents. These scaffolds take up the center position and are the core structural components of numerous drugs that belong to different categories. These include antimicrobial, anti-tubercular, anti-inflammatory, analgesic, antiepileptic, antiviral, and anticancer agents. In this review, we mostly talk about the isomers 1,2,4-oxadiazole and 1,3,4-thiadiazole because they have important pharmacological properties. This is partly because they are chemical and heat resistant, unlike other isomers, and they can be used as bio-isosteric replacements in drug design. We are reviewing the structural modifications of different oxadiazole and thiadiazole derivatives, more specifically, the anti-tubercular and anticancer pharmacological activities reported over the last 5 years, as we have undertaken this as a core area of research. This review article desires to do a thorough study and analysis of the recent progress made in the important biological isomers 1,2,4-oxadiazole and 1,3,4-thiadiazol. This will be a great place to start for future research.

Key points

• Five-membered heterocyclic compound chemistry and biological activity recent survey.

• Synthesis and pharmacological evolution of 1,2,4-oxadiazole and 1,3,4-thiadiazole are discussed in detail.

• The value and significance of heterocyclic compounds in the field of drug designing are highlighted.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00253-022-11969-0.

A Panoramic Review of Benzimidazole Derivatives and Their Potential Biological Activity

The therapeutic potential of the benzimidazole nucleus dates back to 1944, being and important heterocycle system due to its presence in a wide range of bioactive compounds such as antiviral, anticancer, antibacterial, and so on, where optimization of substituents in this class of pharmacophore has resulted in many drugs. Its extensive biological activity is due to its physicochemical properties like hydrogen bond donor-acceptor capability, π → π stacking interactions, coordination bonds with metals as ligands and hydrophobic interactions; properties that allow them to easily bind with a series of biomolecules, including enzymes and nucleic acids, causing a growing interest in these types of molecules. This review aims to present an overview to leading benzimidazole derivatives, as well as to show the importance of the nature and type of substituents at the N1, C2, and C5(6) positions, when they are biologically evaluated, which can lead to obtaining potent drug candidate with significant range of biological activities.

Crystal structure, Hirshfeld and electronic transition analysis of 2-[(1H-benzimidazol-1-yl)meth-yl]benzoic acid

In the title compound, C15H12N2O2, the benzimidazole ring system is inclined to the benzene ring by 78.04 (10)°. The crystal structure features O-H⋯N and C-H⋯O hydrogen bonding and C-H⋯π and π-π inter-actions, which were investigated using Hirshfeld surface analysis.

Anti-tuberculosis activity and its structure-activity relationship (SAR) studies of oxadiazole derivatives: A key review

With the increasing number of cases of inactive and drug-resistance tuberculosis, there is an urgent need to develop new potent molecules set for fighting this brutal disease. Medicinal chemistry concerns the discovery, the development, the identification, and the interpretation of the mode of action of biologically active compounds at the molecular level. Molecules bearing oxadiazoles are one such class that could be considered to satisfy this need. Oxadiazole regioisomers have been investigated in drug discovery programs for their capacity to go about as powerful linkers and as pharmacophoric highlights. Oxadiazoles can go about as bioisosteric substitutions for the hydrazide moiety which can be found in first-line anti-TB drugs, and some have been likewise answered to cooperate with more current anti-TB targets. This present review summarizes the current innovations of oxadiazole-based derivatives with potential antituberculosis activity and bacteria discussing various aspects of structure-activity relationship (SAR).

Benzo[d]imidazol-5-yl)-5-(substituted)-1,3,4-Oxadiazoles: Synthesis, Anticancer, Antimicrobial and In Silico Studies

Background:

Cancer is a fatal disease for mankind; continuous research is still going on for the invention of potent anticancer drugs. In this view, 1, 3, 4-Oxadiazoles are privileged molecules which attracted medicinal chemists towards their anticancer properties.

Methods:

A new series of benzo[d]imidazol-5-yl)-5-(substituted)-1,3,4-oxadiazole derivatives was synthesized in an efficient ‘one-pot’ nitro reductive cyclization using sodium dithionite as a cyclizing agent by a conventional method with good yield. All the structures of the synthesized molecules were characterized by IR, 1H NMR, HRMS and Mass spectral analysis. Anticancer activity screening against A375 melanoma cancer cell line and MDA-MB-231 breast cancer cell line along with antimicrobial activity were carried out using agar well diffusion method.

Results:

Compounds 8a and 8j of the series emerged as potent anticancer agents against A375 melanoma cancer cell line with IC50 47.06 µM and 36.76 µM, respectively. In silico studies also revealed that compounds 8a and 8j showed highest interaction with 2OH4 protein of VEGFR-2 tyrosine kinase. Substantial antibacterial and antifungal activities against the tested microorganism were observed for compounds 8j and 8g.

Conclusion:

Potent anticancer property has been observed with 1,3,4-Oxadiazole linked tetrafluro substituted benzene ring 8j indicating that future research on these type of molecules can be continued to improve the anticancer activity.

Oxadiazole scaffolds in anti-tuberculosis drug discovery

With the increasing number of cases of latent and drug resistant tuberculosis, there is an urgent need to develop new, potent molecules capable of combating this deadly disease. Molecules containing oxadiazoles are one such class that could be considered to fulfil this need. Oxadiazole regioisomers have been explored in drug discovery programs for their ability to act as effective linkers and also as pharmacophoric features. Oxadiazoles can act as bioisosteric replacements for the hydrazide moiety which can be found in first line anti-TB drugs, and some have been also reported to interact with newer anti-TB targets. In this context, the present review describes the potential of oxadiazoles as antituberculosis agents.

Recent advances of imidazole-containing derivatives as anti-tubercular agents

Tuberculosis still remains one of the most common, communicable, and leading deadliest diseases known to mankind throughout the world. Drug-resistance in Mycobacterium tuberculosis which threatens to worsen the global tuberculosis epidemic has caused great concern in recent years. To overcome the resistance, the development of new drugs with novel mechanisms of actions is of great importance. Imidazole-containing derivatives endow with various biological properties, and some of them demonstrated excellent anti-tubercular activity. As the most emblematic example, 4-nitroimidazole delamanid has already received approval for treatment of multidrug-resistant tuberculosis infected patients. Thus, imidazole-containing derivatives have caused great interests in discovery of new anti-tubercular agents. Numerous of imidazole-containing derivatives were synthesized and screened for their in vitro and in vivo anti-mycobacterial activities against both drug-sensitive and drug-resistant Mycobacterium tuberculosis pathogens. This review aims to outline the recent advances of imidazole-containing derivatives as anti-tubercular agents, and summarize the structure-activity relationship of these derivatives. The enriched structure-activity relationship may pave the way for the further rational development of imidazole-containing derivatives as anti-tubercular agents.